1 /* Common subexpression elimination for GNU compiler.
2 Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998
3 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 /* stdio.h must precede rtl.h for FFS. */
25 #include "coretypes.h"
31 #include "hard-reg-set.h"
32 #include "basic-block.h"
35 #include "insn-config.h"
47 /* The basic idea of common subexpression elimination is to go
48 through the code, keeping a record of expressions that would
49 have the same value at the current scan point, and replacing
50 expressions encountered with the cheapest equivalent expression.
52 It is too complicated to keep track of the different possibilities
53 when control paths merge in this code; so, at each label, we forget all
54 that is known and start fresh. This can be described as processing each
55 extended basic block separately. We have a separate pass to perform
58 Note CSE can turn a conditional or computed jump into a nop or
59 an unconditional jump. When this occurs we arrange to run the jump
60 optimizer after CSE to delete the unreachable code.
62 We use two data structures to record the equivalent expressions:
63 a hash table for most expressions, and a vector of "quantity
64 numbers" to record equivalent (pseudo) registers.
66 The use of the special data structure for registers is desirable
67 because it is faster. It is possible because registers references
68 contain a fairly small number, the register number, taken from
69 a contiguously allocated series, and two register references are
70 identical if they have the same number. General expressions
71 do not have any such thing, so the only way to retrieve the
72 information recorded on an expression other than a register
73 is to keep it in a hash table.
75 Registers and "quantity numbers":
77 At the start of each basic block, all of the (hardware and pseudo)
78 registers used in the function are given distinct quantity
79 numbers to indicate their contents. During scan, when the code
80 copies one register into another, we copy the quantity number.
81 When a register is loaded in any other way, we allocate a new
82 quantity number to describe the value generated by this operation.
83 `reg_qty' records what quantity a register is currently thought
86 All real quantity numbers are greater than or equal to `max_reg'.
87 If register N has not been assigned a quantity, reg_qty[N] will equal N.
89 Quantity numbers below `max_reg' do not exist and none of the `qty_table'
90 entries should be referenced with an index below `max_reg'.
92 We also maintain a bidirectional chain of registers for each
93 quantity number. The `qty_table` members `first_reg' and `last_reg',
94 and `reg_eqv_table' members `next' and `prev' hold these chains.
96 The first register in a chain is the one whose lifespan is least local.
97 Among equals, it is the one that was seen first.
98 We replace any equivalent register with that one.
100 If two registers have the same quantity number, it must be true that
101 REG expressions with qty_table `mode' must be in the hash table for both
102 registers and must be in the same class.
104 The converse is not true. Since hard registers may be referenced in
105 any mode, two REG expressions might be equivalent in the hash table
106 but not have the same quantity number if the quantity number of one
107 of the registers is not the same mode as those expressions.
109 Constants and quantity numbers
111 When a quantity has a known constant value, that value is stored
112 in the appropriate qty_table `const_rtx'. This is in addition to
113 putting the constant in the hash table as is usual for non-regs.
115 Whether a reg or a constant is preferred is determined by the configuration
116 macro CONST_COSTS and will often depend on the constant value. In any
117 event, expressions containing constants can be simplified, by fold_rtx.
119 When a quantity has a known nearly constant value (such as an address
120 of a stack slot), that value is stored in the appropriate qty_table
123 Integer constants don't have a machine mode. However, cse
124 determines the intended machine mode from the destination
125 of the instruction that moves the constant. The machine mode
126 is recorded in the hash table along with the actual RTL
127 constant expression so that different modes are kept separate.
131 To record known equivalences among expressions in general
132 we use a hash table called `table'. It has a fixed number of buckets
133 that contain chains of `struct table_elt' elements for expressions.
134 These chains connect the elements whose expressions have the same
137 Other chains through the same elements connect the elements which
138 currently have equivalent values.
140 Register references in an expression are canonicalized before hashing
141 the expression. This is done using `reg_qty' and qty_table `first_reg'.
142 The hash code of a register reference is computed using the quantity
143 number, not the register number.
145 When the value of an expression changes, it is necessary to remove from the
146 hash table not just that expression but all expressions whose values
147 could be different as a result.
149 1. If the value changing is in memory, except in special cases
150 ANYTHING referring to memory could be changed. That is because
151 nobody knows where a pointer does not point.
152 The function `invalidate_memory' removes what is necessary.
154 The special cases are when the address is constant or is
155 a constant plus a fixed register such as the frame pointer
156 or a static chain pointer. When such addresses are stored in,
157 we can tell exactly which other such addresses must be invalidated
158 due to overlap. `invalidate' does this.
159 All expressions that refer to non-constant
160 memory addresses are also invalidated. `invalidate_memory' does this.
162 2. If the value changing is a register, all expressions
163 containing references to that register, and only those,
166 Because searching the entire hash table for expressions that contain
167 a register is very slow, we try to figure out when it isn't necessary.
168 Precisely, this is necessary only when expressions have been
169 entered in the hash table using this register, and then the value has
170 changed, and then another expression wants to be added to refer to
171 the register's new value. This sequence of circumstances is rare
172 within any one basic block.
174 The vectors `reg_tick' and `reg_in_table' are used to detect this case.
175 reg_tick[i] is incremented whenever a value is stored in register i.
176 reg_in_table[i] holds -1 if no references to register i have been
177 entered in the table; otherwise, it contains the value reg_tick[i] had
178 when the references were entered. If we want to enter a reference
179 and reg_in_table[i] != reg_tick[i], we must scan and remove old references.
180 Until we want to enter a new entry, the mere fact that the two vectors
181 don't match makes the entries be ignored if anyone tries to match them.
183 Registers themselves are entered in the hash table as well as in
184 the equivalent-register chains. However, the vectors `reg_tick'
185 and `reg_in_table' do not apply to expressions which are simple
186 register references. These expressions are removed from the table
187 immediately when they become invalid, and this can be done even if
188 we do not immediately search for all the expressions that refer to
191 A CLOBBER rtx in an instruction invalidates its operand for further
192 reuse. A CLOBBER or SET rtx whose operand is a MEM:BLK
193 invalidates everything that resides in memory.
197 Constant expressions that differ only by an additive integer
198 are called related. When a constant expression is put in
199 the table, the related expression with no constant term
200 is also entered. These are made to point at each other
201 so that it is possible to find out if there exists any
202 register equivalent to an expression related to a given expression. */
204 /* One plus largest register number used in this function. */
208 /* One plus largest instruction UID used in this function at time of
211 static int max_insn_uid
;
213 /* Length of qty_table vector. We know in advance we will not need
214 a quantity number this big. */
218 /* Next quantity number to be allocated.
219 This is 1 + the largest number needed so far. */
223 /* Per-qty information tracking.
225 `first_reg' and `last_reg' track the head and tail of the
226 chain of registers which currently contain this quantity.
228 `mode' contains the machine mode of this quantity.
230 `const_rtx' holds the rtx of the constant value of this
231 quantity, if known. A summations of the frame/arg pointer
232 and a constant can also be entered here. When this holds
233 a known value, `const_insn' is the insn which stored the
236 `comparison_{code,const,qty}' are used to track when a
237 comparison between a quantity and some constant or register has
238 been passed. In such a case, we know the results of the comparison
239 in case we see it again. These members record a comparison that
240 is known to be true. `comparison_code' holds the rtx code of such
241 a comparison, else it is set to UNKNOWN and the other two
242 comparison members are undefined. `comparison_const' holds
243 the constant being compared against, or zero if the comparison
244 is not against a constant. `comparison_qty' holds the quantity
245 being compared against when the result is known. If the comparison
246 is not with a register, `comparison_qty' is -1. */
248 struct qty_table_elem
252 rtx comparison_const
;
254 unsigned int first_reg
, last_reg
;
255 /* The sizes of these fields should match the sizes of the
256 code and mode fields of struct rtx_def (see rtl.h). */
257 ENUM_BITFIELD(rtx_code
) comparison_code
: 16;
258 ENUM_BITFIELD(machine_mode
) mode
: 8;
261 /* The table of all qtys, indexed by qty number. */
262 static struct qty_table_elem
*qty_table
;
265 /* For machines that have a CC0, we do not record its value in the hash
266 table since its use is guaranteed to be the insn immediately following
267 its definition and any other insn is presumed to invalidate it.
269 Instead, we store below the value last assigned to CC0. If it should
270 happen to be a constant, it is stored in preference to the actual
271 assigned value. In case it is a constant, we store the mode in which
272 the constant should be interpreted. */
274 static rtx prev_insn_cc0
;
275 static enum machine_mode prev_insn_cc0_mode
;
277 /* Previous actual insn. 0 if at first insn of basic block. */
279 static rtx prev_insn
;
282 /* Insn being scanned. */
284 static rtx this_insn
;
286 /* Index by register number, gives the number of the next (or
287 previous) register in the chain of registers sharing the same
290 Or -1 if this register is at the end of the chain.
292 If reg_qty[N] == N, reg_eqv_table[N].next is undefined. */
294 /* Per-register equivalence chain. */
300 /* The table of all register equivalence chains. */
301 static struct reg_eqv_elem
*reg_eqv_table
;
305 /* Next in hash chain. */
306 struct cse_reg_info
*hash_next
;
308 /* The next cse_reg_info structure in the free or used list. */
309 struct cse_reg_info
*next
;
314 /* The quantity number of the register's current contents. */
317 /* The number of times the register has been altered in the current
321 /* The REG_TICK value at which rtx's containing this register are
322 valid in the hash table. If this does not equal the current
323 reg_tick value, such expressions existing in the hash table are
327 /* The SUBREG that was set when REG_TICK was last incremented. Set
328 to -1 if the last store was to the whole register, not a subreg. */
329 unsigned int subreg_ticked
;
332 /* A free list of cse_reg_info entries. */
333 static struct cse_reg_info
*cse_reg_info_free_list
;
335 /* A used list of cse_reg_info entries. */
336 static struct cse_reg_info
*cse_reg_info_used_list
;
337 static struct cse_reg_info
*cse_reg_info_used_list_end
;
339 /* A mapping from registers to cse_reg_info data structures. */
340 #define REGHASH_SHIFT 7
341 #define REGHASH_SIZE (1 << REGHASH_SHIFT)
342 #define REGHASH_MASK (REGHASH_SIZE - 1)
343 static struct cse_reg_info
*reg_hash
[REGHASH_SIZE
];
345 #define REGHASH_FN(REGNO) \
346 (((REGNO) ^ ((REGNO) >> REGHASH_SHIFT)) & REGHASH_MASK)
348 /* The last lookup we did into the cse_reg_info_tree. This allows us
349 to cache repeated lookups. */
350 static unsigned int cached_regno
;
351 static struct cse_reg_info
*cached_cse_reg_info
;
353 /* A HARD_REG_SET containing all the hard registers for which there is
354 currently a REG expression in the hash table. Note the difference
355 from the above variables, which indicate if the REG is mentioned in some
356 expression in the table. */
358 static HARD_REG_SET hard_regs_in_table
;
360 /* CUID of insn that starts the basic block currently being cse-processed. */
362 static int cse_basic_block_start
;
364 /* CUID of insn that ends the basic block currently being cse-processed. */
366 static int cse_basic_block_end
;
368 /* Vector mapping INSN_UIDs to cuids.
369 The cuids are like uids but increase monotonically always.
370 We use them to see whether a reg is used outside a given basic block. */
372 static int *uid_cuid
;
374 /* Highest UID in UID_CUID. */
377 /* Get the cuid of an insn. */
379 #define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
381 /* Nonzero if this pass has made changes, and therefore it's
382 worthwhile to run the garbage collector. */
384 static int cse_altered
;
386 /* Nonzero if cse has altered conditional jump insns
387 in such a way that jump optimization should be redone. */
389 static int cse_jumps_altered
;
391 /* Nonzero if we put a LABEL_REF into the hash table for an INSN without a
392 REG_LABEL, we have to rerun jump after CSE to put in the note. */
393 static int recorded_label_ref
;
395 /* canon_hash stores 1 in do_not_record
396 if it notices a reference to CC0, PC, or some other volatile
399 static int do_not_record
;
401 #ifdef LOAD_EXTEND_OP
403 /* Scratch rtl used when looking for load-extended copy of a MEM. */
404 static rtx memory_extend_rtx
;
407 /* canon_hash stores 1 in hash_arg_in_memory
408 if it notices a reference to memory within the expression being hashed. */
410 static int hash_arg_in_memory
;
412 /* The hash table contains buckets which are chains of `struct table_elt's,
413 each recording one expression's information.
414 That expression is in the `exp' field.
416 The canon_exp field contains a canonical (from the point of view of
417 alias analysis) version of the `exp' field.
419 Those elements with the same hash code are chained in both directions
420 through the `next_same_hash' and `prev_same_hash' fields.
422 Each set of expressions with equivalent values
423 are on a two-way chain through the `next_same_value'
424 and `prev_same_value' fields, and all point with
425 the `first_same_value' field at the first element in
426 that chain. The chain is in order of increasing cost.
427 Each element's cost value is in its `cost' field.
429 The `in_memory' field is nonzero for elements that
430 involve any reference to memory. These elements are removed
431 whenever a write is done to an unidentified location in memory.
432 To be safe, we assume that a memory address is unidentified unless
433 the address is either a symbol constant or a constant plus
434 the frame pointer or argument pointer.
436 The `related_value' field is used to connect related expressions
437 (that differ by adding an integer).
438 The related expressions are chained in a circular fashion.
439 `related_value' is zero for expressions for which this
442 The `cost' field stores the cost of this element's expression.
443 The `regcost' field stores the value returned by approx_reg_cost for
444 this element's expression.
446 The `is_const' flag is set if the element is a constant (including
449 The `flag' field is used as a temporary during some search routines.
451 The `mode' field is usually the same as GET_MODE (`exp'), but
452 if `exp' is a CONST_INT and has no machine mode then the `mode'
453 field is the mode it was being used as. Each constant is
454 recorded separately for each mode it is used with. */
460 struct table_elt
*next_same_hash
;
461 struct table_elt
*prev_same_hash
;
462 struct table_elt
*next_same_value
;
463 struct table_elt
*prev_same_value
;
464 struct table_elt
*first_same_value
;
465 struct table_elt
*related_value
;
468 /* The size of this field should match the size
469 of the mode field of struct rtx_def (see rtl.h). */
470 ENUM_BITFIELD(machine_mode
) mode
: 8;
476 /* We don't want a lot of buckets, because we rarely have very many
477 things stored in the hash table, and a lot of buckets slows
478 down a lot of loops that happen frequently. */
480 #define HASH_SIZE (1 << HASH_SHIFT)
481 #define HASH_MASK (HASH_SIZE - 1)
483 /* Compute hash code of X in mode M. Special-case case where X is a pseudo
484 register (hard registers may require `do_not_record' to be set). */
487 ((GET_CODE (X) == REG && REGNO (X) >= FIRST_PSEUDO_REGISTER \
488 ? (((unsigned) REG << 7) + (unsigned) REG_QTY (REGNO (X))) \
489 : canon_hash (X, M)) & HASH_MASK)
491 /* Determine whether register number N is considered a fixed register for the
492 purpose of approximating register costs.
493 It is desirable to replace other regs with fixed regs, to reduce need for
495 A reg wins if it is either the frame pointer or designated as fixed. */
496 #define FIXED_REGNO_P(N) \
497 ((N) == FRAME_POINTER_REGNUM || (N) == HARD_FRAME_POINTER_REGNUM \
498 || fixed_regs[N] || global_regs[N])
500 /* Compute cost of X, as stored in the `cost' field of a table_elt. Fixed
501 hard registers and pointers into the frame are the cheapest with a cost
502 of 0. Next come pseudos with a cost of one and other hard registers with
503 a cost of 2. Aside from these special cases, call `rtx_cost'. */
505 #define CHEAP_REGNO(N) \
506 ((N) == FRAME_POINTER_REGNUM || (N) == HARD_FRAME_POINTER_REGNUM \
507 || (N) == STACK_POINTER_REGNUM || (N) == ARG_POINTER_REGNUM \
508 || ((N) >= FIRST_VIRTUAL_REGISTER && (N) <= LAST_VIRTUAL_REGISTER) \
509 || ((N) < FIRST_PSEUDO_REGISTER \
510 && FIXED_REGNO_P (N) && REGNO_REG_CLASS (N) != NO_REGS))
512 #define COST(X) (GET_CODE (X) == REG ? 0 : notreg_cost (X, SET))
513 #define COST_IN(X,OUTER) (GET_CODE (X) == REG ? 0 : notreg_cost (X, OUTER))
515 /* Get the info associated with register N. */
517 #define GET_CSE_REG_INFO(N) \
518 (((N) == cached_regno && cached_cse_reg_info) \
519 ? cached_cse_reg_info : get_cse_reg_info ((N)))
521 /* Get the number of times this register has been updated in this
524 #define REG_TICK(N) ((GET_CSE_REG_INFO (N))->reg_tick)
526 /* Get the point at which REG was recorded in the table. */
528 #define REG_IN_TABLE(N) ((GET_CSE_REG_INFO (N))->reg_in_table)
530 /* Get the SUBREG set at the last increment to REG_TICK (-1 if not a
533 #define SUBREG_TICKED(N) ((GET_CSE_REG_INFO (N))->subreg_ticked)
535 /* Get the quantity number for REG. */
537 #define REG_QTY(N) ((GET_CSE_REG_INFO (N))->reg_qty)
539 /* Determine if the quantity number for register X represents a valid index
540 into the qty_table. */
542 #define REGNO_QTY_VALID_P(N) (REG_QTY (N) != (int) (N))
544 static struct table_elt
*table
[HASH_SIZE
];
546 /* Chain of `struct table_elt's made so far for this function
547 but currently removed from the table. */
549 static struct table_elt
*free_element_chain
;
551 /* Number of `struct table_elt' structures made so far for this function. */
553 static int n_elements_made
;
555 /* Maximum value `n_elements_made' has had so far in this compilation
556 for functions previously processed. */
558 static int max_elements_made
;
560 /* Surviving equivalence class when two equivalence classes are merged
561 by recording the effects of a jump in the last insn. Zero if the
562 last insn was not a conditional jump. */
564 static struct table_elt
*last_jump_equiv_class
;
566 /* Set to the cost of a constant pool reference if one was found for a
567 symbolic constant. If this was found, it means we should try to
568 convert constants into constant pool entries if they don't fit in
571 static int constant_pool_entries_cost
;
573 /* This data describes a block that will be processed by cse_basic_block. */
575 struct cse_basic_block_data
577 /* Lowest CUID value of insns in block. */
579 /* Highest CUID value of insns in block. */
581 /* Total number of SETs in block. */
583 /* Last insn in the block. */
585 /* Size of current branch path, if any. */
587 /* Current branch path, indicating which branches will be taken. */
590 /* The branch insn. */
592 /* Whether it should be taken or not. AROUND is the same as taken
593 except that it is used when the destination label is not preceded
595 enum taken
{TAKEN
, NOT_TAKEN
, AROUND
} status
;
599 static bool fixed_base_plus_p
PARAMS ((rtx x
));
600 static int notreg_cost
PARAMS ((rtx
, enum rtx_code
));
601 static int approx_reg_cost_1
PARAMS ((rtx
*, void *));
602 static int approx_reg_cost
PARAMS ((rtx
));
603 static int preferrable
PARAMS ((int, int, int, int));
604 static void new_basic_block
PARAMS ((void));
605 static void make_new_qty
PARAMS ((unsigned int, enum machine_mode
));
606 static void make_regs_eqv
PARAMS ((unsigned int, unsigned int));
607 static void delete_reg_equiv
PARAMS ((unsigned int));
608 static int mention_regs
PARAMS ((rtx
));
609 static int insert_regs
PARAMS ((rtx
, struct table_elt
*, int));
610 static void remove_from_table
PARAMS ((struct table_elt
*, unsigned));
611 static struct table_elt
*lookup
PARAMS ((rtx
, unsigned, enum machine_mode
)),
612 *lookup_for_remove
PARAMS ((rtx
, unsigned, enum machine_mode
));
613 static rtx lookup_as_function
PARAMS ((rtx
, enum rtx_code
));
614 static struct table_elt
*insert
PARAMS ((rtx
, struct table_elt
*, unsigned,
616 static void merge_equiv_classes
PARAMS ((struct table_elt
*,
617 struct table_elt
*));
618 static void invalidate
PARAMS ((rtx
, enum machine_mode
));
619 static int cse_rtx_varies_p
PARAMS ((rtx
, int));
620 static void remove_invalid_refs
PARAMS ((unsigned int));
621 static void remove_invalid_subreg_refs
PARAMS ((unsigned int, unsigned int,
623 static void rehash_using_reg
PARAMS ((rtx
));
624 static void invalidate_memory
PARAMS ((void));
625 static void invalidate_for_call
PARAMS ((void));
626 static rtx use_related_value
PARAMS ((rtx
, struct table_elt
*));
627 static unsigned canon_hash
PARAMS ((rtx
, enum machine_mode
));
628 static unsigned canon_hash_string
PARAMS ((const char *));
629 static unsigned safe_hash
PARAMS ((rtx
, enum machine_mode
));
630 static int exp_equiv_p
PARAMS ((rtx
, rtx
, int, int));
631 static rtx canon_reg
PARAMS ((rtx
, rtx
));
632 static void find_best_addr
PARAMS ((rtx
, rtx
*, enum machine_mode
));
633 static enum rtx_code find_comparison_args
PARAMS ((enum rtx_code
, rtx
*, rtx
*,
635 enum machine_mode
*));
636 static rtx fold_rtx
PARAMS ((rtx
, rtx
));
637 static rtx equiv_constant
PARAMS ((rtx
));
638 static void record_jump_equiv
PARAMS ((rtx
, int));
639 static void record_jump_cond
PARAMS ((enum rtx_code
, enum machine_mode
,
641 static void cse_insn
PARAMS ((rtx
, rtx
));
642 static int addr_affects_sp_p
PARAMS ((rtx
));
643 static void invalidate_from_clobbers
PARAMS ((rtx
));
644 static rtx cse_process_notes
PARAMS ((rtx
, rtx
));
645 static void cse_around_loop
PARAMS ((rtx
));
646 static void invalidate_skipped_set
PARAMS ((rtx
, rtx
, void *));
647 static void invalidate_skipped_block
PARAMS ((rtx
));
648 static void cse_check_loop_start
PARAMS ((rtx
, rtx
, void *));
649 static void cse_set_around_loop
PARAMS ((rtx
, rtx
, rtx
));
650 static rtx cse_basic_block
PARAMS ((rtx
, rtx
, struct branch_path
*, int));
651 static void count_reg_usage
PARAMS ((rtx
, int *, rtx
, int));
652 static int check_for_label_ref
PARAMS ((rtx
*, void *));
653 extern void dump_class
PARAMS ((struct table_elt
*));
654 static struct cse_reg_info
* get_cse_reg_info
PARAMS ((unsigned int));
655 static int check_dependence
PARAMS ((rtx
*, void *));
657 static void flush_hash_table
PARAMS ((void));
658 static bool insn_live_p
PARAMS ((rtx
, int *));
659 static bool set_live_p
PARAMS ((rtx
, rtx
, int *));
660 static bool dead_libcall_p
PARAMS ((rtx
, int *));
662 /* Nonzero if X has the form (PLUS frame-pointer integer). We check for
663 virtual regs here because the simplify_*_operation routines are called
664 by integrate.c, which is called before virtual register instantiation. */
667 fixed_base_plus_p (x
)
670 switch (GET_CODE (x
))
673 if (x
== frame_pointer_rtx
|| x
== hard_frame_pointer_rtx
)
675 if (x
== arg_pointer_rtx
&& fixed_regs
[ARG_POINTER_REGNUM
])
677 if (REGNO (x
) >= FIRST_VIRTUAL_REGISTER
678 && REGNO (x
) <= LAST_VIRTUAL_REGISTER
)
683 if (GET_CODE (XEXP (x
, 1)) != CONST_INT
)
685 return fixed_base_plus_p (XEXP (x
, 0));
695 /* Dump the expressions in the equivalence class indicated by CLASSP.
696 This function is used only for debugging. */
699 struct table_elt
*classp
;
701 struct table_elt
*elt
;
703 fprintf (stderr
, "Equivalence chain for ");
704 print_rtl (stderr
, classp
->exp
);
705 fprintf (stderr
, ": \n");
707 for (elt
= classp
->first_same_value
; elt
; elt
= elt
->next_same_value
)
709 print_rtl (stderr
, elt
->exp
);
710 fprintf (stderr
, "\n");
714 /* Subroutine of approx_reg_cost; called through for_each_rtx. */
717 approx_reg_cost_1 (xp
, data
)
724 if (x
&& GET_CODE (x
) == REG
)
726 unsigned int regno
= REGNO (x
);
728 if (! CHEAP_REGNO (regno
))
730 if (regno
< FIRST_PSEUDO_REGISTER
)
732 if (SMALL_REGISTER_CLASSES
)
744 /* Return an estimate of the cost of the registers used in an rtx.
745 This is mostly the number of different REG expressions in the rtx;
746 however for some exceptions like fixed registers we use a cost of
747 0. If any other hard register reference occurs, return MAX_COST. */
755 if (for_each_rtx (&x
, approx_reg_cost_1
, (void *) &cost
))
761 /* Return a negative value if an rtx A, whose costs are given by COST_A
762 and REGCOST_A, is more desirable than an rtx B.
763 Return a positive value if A is less desirable, or 0 if the two are
766 preferrable (cost_a
, regcost_a
, cost_b
, regcost_b
)
767 int cost_a
, regcost_a
, cost_b
, regcost_b
;
769 /* First, get rid of cases involving expressions that are entirely
771 if (cost_a
!= cost_b
)
773 if (cost_a
== MAX_COST
)
775 if (cost_b
== MAX_COST
)
779 /* Avoid extending lifetimes of hardregs. */
780 if (regcost_a
!= regcost_b
)
782 if (regcost_a
== MAX_COST
)
784 if (regcost_b
== MAX_COST
)
788 /* Normal operation costs take precedence. */
789 if (cost_a
!= cost_b
)
790 return cost_a
- cost_b
;
791 /* Only if these are identical consider effects on register pressure. */
792 if (regcost_a
!= regcost_b
)
793 return regcost_a
- regcost_b
;
797 /* Internal function, to compute cost when X is not a register; called
798 from COST macro to keep it simple. */
801 notreg_cost (x
, outer
)
805 return ((GET_CODE (x
) == SUBREG
806 && GET_CODE (SUBREG_REG (x
)) == REG
807 && GET_MODE_CLASS (GET_MODE (x
)) == MODE_INT
808 && GET_MODE_CLASS (GET_MODE (SUBREG_REG (x
))) == MODE_INT
809 && (GET_MODE_SIZE (GET_MODE (x
))
810 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (x
))))
811 && subreg_lowpart_p (x
)
812 && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (GET_MODE (x
)),
813 GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (x
)))))
815 : rtx_cost (x
, outer
) * 2);
818 /* Return an estimate of the cost of computing rtx X.
819 One use is in cse, to decide which expression to keep in the hash table.
820 Another is in rtl generation, to pick the cheapest way to multiply.
821 Other uses like the latter are expected in the future. */
824 rtx_cost (x
, outer_code
)
826 enum rtx_code outer_code ATTRIBUTE_UNUSED
;
836 /* Compute the default costs of certain things.
837 Note that targetm.rtx_costs can override the defaults. */
843 total
= COSTS_N_INSNS (5);
849 total
= COSTS_N_INSNS (7);
852 /* Used in loop.c and combine.c as a marker. */
856 total
= COSTS_N_INSNS (1);
865 /* If we can't tie these modes, make this expensive. The larger
866 the mode, the more expensive it is. */
867 if (! MODES_TIEABLE_P (GET_MODE (x
), GET_MODE (SUBREG_REG (x
))))
868 return COSTS_N_INSNS (2
869 + GET_MODE_SIZE (GET_MODE (x
)) / UNITS_PER_WORD
);
873 if ((*targetm
.rtx_costs
) (x
, code
, outer_code
, &total
))
878 /* Sum the costs of the sub-rtx's, plus cost of this operation,
879 which is already in total. */
881 fmt
= GET_RTX_FORMAT (code
);
882 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
884 total
+= rtx_cost (XEXP (x
, i
), code
);
885 else if (fmt
[i
] == 'E')
886 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
887 total
+= rtx_cost (XVECEXP (x
, i
, j
), code
);
892 /* Return cost of address expression X.
893 Expect that X is properly formed address reference. */
896 address_cost (x
, mode
)
898 enum machine_mode mode
;
900 /* The address_cost target hook does not deal with ADDRESSOF nodes. But,
901 during CSE, such nodes are present. Using an ADDRESSOF node which
902 refers to the address of a REG is a good thing because we can then
903 turn (MEM (ADDRESSSOF (REG))) into just plain REG. */
905 if (GET_CODE (x
) == ADDRESSOF
&& REG_P (XEXP ((x
), 0)))
908 /* We may be asked for cost of various unusual addresses, such as operands
909 of push instruction. It is not worthwhile to complicate writing
910 of the target hook by such cases. */
912 if (!memory_address_p (mode
, x
))
915 return (*targetm
.address_cost
) (x
);
918 /* If the target doesn't override, compute the cost as with arithmetic. */
921 default_address_cost (x
)
924 return rtx_cost (x
, MEM
);
927 static struct cse_reg_info
*
928 get_cse_reg_info (regno
)
931 struct cse_reg_info
**hash_head
= ®_hash
[REGHASH_FN (regno
)];
932 struct cse_reg_info
*p
;
934 for (p
= *hash_head
; p
!= NULL
; p
= p
->hash_next
)
935 if (p
->regno
== regno
)
940 /* Get a new cse_reg_info structure. */
941 if (cse_reg_info_free_list
)
943 p
= cse_reg_info_free_list
;
944 cse_reg_info_free_list
= p
->next
;
947 p
= (struct cse_reg_info
*) xmalloc (sizeof (struct cse_reg_info
));
949 /* Insert into hash table. */
950 p
->hash_next
= *hash_head
;
955 p
->reg_in_table
= -1;
956 p
->subreg_ticked
= -1;
959 p
->next
= cse_reg_info_used_list
;
960 cse_reg_info_used_list
= p
;
961 if (!cse_reg_info_used_list_end
)
962 cse_reg_info_used_list_end
= p
;
965 /* Cache this lookup; we tend to be looking up information about the
966 same register several times in a row. */
967 cached_regno
= regno
;
968 cached_cse_reg_info
= p
;
973 /* Clear the hash table and initialize each register with its own quantity,
974 for a new basic block. */
983 /* Clear out hash table state for this pass. */
985 memset ((char *) reg_hash
, 0, sizeof reg_hash
);
987 if (cse_reg_info_used_list
)
989 cse_reg_info_used_list_end
->next
= cse_reg_info_free_list
;
990 cse_reg_info_free_list
= cse_reg_info_used_list
;
991 cse_reg_info_used_list
= cse_reg_info_used_list_end
= 0;
993 cached_cse_reg_info
= 0;
995 CLEAR_HARD_REG_SET (hard_regs_in_table
);
997 /* The per-quantity values used to be initialized here, but it is
998 much faster to initialize each as it is made in `make_new_qty'. */
1000 for (i
= 0; i
< HASH_SIZE
; i
++)
1002 struct table_elt
*first
;
1007 struct table_elt
*last
= first
;
1011 while (last
->next_same_hash
!= NULL
)
1012 last
= last
->next_same_hash
;
1014 /* Now relink this hash entire chain into
1015 the free element list. */
1017 last
->next_same_hash
= free_element_chain
;
1018 free_element_chain
= first
;
1028 /* Say that register REG contains a quantity in mode MODE not in any
1029 register before and initialize that quantity. */
1032 make_new_qty (reg
, mode
)
1034 enum machine_mode mode
;
1037 struct qty_table_elem
*ent
;
1038 struct reg_eqv_elem
*eqv
;
1040 if (next_qty
>= max_qty
)
1043 q
= REG_QTY (reg
) = next_qty
++;
1044 ent
= &qty_table
[q
];
1045 ent
->first_reg
= reg
;
1046 ent
->last_reg
= reg
;
1048 ent
->const_rtx
= ent
->const_insn
= NULL_RTX
;
1049 ent
->comparison_code
= UNKNOWN
;
1051 eqv
= ®_eqv_table
[reg
];
1052 eqv
->next
= eqv
->prev
= -1;
1055 /* Make reg NEW equivalent to reg OLD.
1056 OLD is not changing; NEW is. */
1059 make_regs_eqv (new, old
)
1060 unsigned int new, old
;
1062 unsigned int lastr
, firstr
;
1063 int q
= REG_QTY (old
);
1064 struct qty_table_elem
*ent
;
1066 ent
= &qty_table
[q
];
1068 /* Nothing should become eqv until it has a "non-invalid" qty number. */
1069 if (! REGNO_QTY_VALID_P (old
))
1073 firstr
= ent
->first_reg
;
1074 lastr
= ent
->last_reg
;
1076 /* Prefer fixed hard registers to anything. Prefer pseudo regs to other
1077 hard regs. Among pseudos, if NEW will live longer than any other reg
1078 of the same qty, and that is beyond the current basic block,
1079 make it the new canonical replacement for this qty. */
1080 if (! (firstr
< FIRST_PSEUDO_REGISTER
&& FIXED_REGNO_P (firstr
))
1081 /* Certain fixed registers might be of the class NO_REGS. This means
1082 that not only can they not be allocated by the compiler, but
1083 they cannot be used in substitutions or canonicalizations
1085 && (new >= FIRST_PSEUDO_REGISTER
|| REGNO_REG_CLASS (new) != NO_REGS
)
1086 && ((new < FIRST_PSEUDO_REGISTER
&& FIXED_REGNO_P (new))
1087 || (new >= FIRST_PSEUDO_REGISTER
1088 && (firstr
< FIRST_PSEUDO_REGISTER
1089 || ((uid_cuid
[REGNO_LAST_UID (new)] > cse_basic_block_end
1090 || (uid_cuid
[REGNO_FIRST_UID (new)]
1091 < cse_basic_block_start
))
1092 && (uid_cuid
[REGNO_LAST_UID (new)]
1093 > uid_cuid
[REGNO_LAST_UID (firstr
)]))))))
1095 reg_eqv_table
[firstr
].prev
= new;
1096 reg_eqv_table
[new].next
= firstr
;
1097 reg_eqv_table
[new].prev
= -1;
1098 ent
->first_reg
= new;
1102 /* If NEW is a hard reg (known to be non-fixed), insert at end.
1103 Otherwise, insert before any non-fixed hard regs that are at the
1104 end. Registers of class NO_REGS cannot be used as an
1105 equivalent for anything. */
1106 while (lastr
< FIRST_PSEUDO_REGISTER
&& reg_eqv_table
[lastr
].prev
>= 0
1107 && (REGNO_REG_CLASS (lastr
) == NO_REGS
|| ! FIXED_REGNO_P (lastr
))
1108 && new >= FIRST_PSEUDO_REGISTER
)
1109 lastr
= reg_eqv_table
[lastr
].prev
;
1110 reg_eqv_table
[new].next
= reg_eqv_table
[lastr
].next
;
1111 if (reg_eqv_table
[lastr
].next
>= 0)
1112 reg_eqv_table
[reg_eqv_table
[lastr
].next
].prev
= new;
1114 qty_table
[q
].last_reg
= new;
1115 reg_eqv_table
[lastr
].next
= new;
1116 reg_eqv_table
[new].prev
= lastr
;
1120 /* Remove REG from its equivalence class. */
1123 delete_reg_equiv (reg
)
1126 struct qty_table_elem
*ent
;
1127 int q
= REG_QTY (reg
);
1130 /* If invalid, do nothing. */
1134 ent
= &qty_table
[q
];
1136 p
= reg_eqv_table
[reg
].prev
;
1137 n
= reg_eqv_table
[reg
].next
;
1140 reg_eqv_table
[n
].prev
= p
;
1144 reg_eqv_table
[p
].next
= n
;
1148 REG_QTY (reg
) = reg
;
1151 /* Remove any invalid expressions from the hash table
1152 that refer to any of the registers contained in expression X.
1154 Make sure that newly inserted references to those registers
1155 as subexpressions will be considered valid.
1157 mention_regs is not called when a register itself
1158 is being stored in the table.
1160 Return 1 if we have done something that may have changed the hash code
1175 code
= GET_CODE (x
);
1178 unsigned int regno
= REGNO (x
);
1179 unsigned int endregno
1180 = regno
+ (regno
>= FIRST_PSEUDO_REGISTER
? 1
1181 : HARD_REGNO_NREGS (regno
, GET_MODE (x
)));
1184 for (i
= regno
; i
< endregno
; i
++)
1186 if (REG_IN_TABLE (i
) >= 0 && REG_IN_TABLE (i
) != REG_TICK (i
))
1187 remove_invalid_refs (i
);
1189 REG_IN_TABLE (i
) = REG_TICK (i
);
1190 SUBREG_TICKED (i
) = -1;
1196 /* If this is a SUBREG, we don't want to discard other SUBREGs of the same
1197 pseudo if they don't use overlapping words. We handle only pseudos
1198 here for simplicity. */
1199 if (code
== SUBREG
&& GET_CODE (SUBREG_REG (x
)) == REG
1200 && REGNO (SUBREG_REG (x
)) >= FIRST_PSEUDO_REGISTER
)
1202 unsigned int i
= REGNO (SUBREG_REG (x
));
1204 if (REG_IN_TABLE (i
) >= 0 && REG_IN_TABLE (i
) != REG_TICK (i
))
1206 /* If REG_IN_TABLE (i) differs from REG_TICK (i) by one, and
1207 the last store to this register really stored into this
1208 subreg, then remove the memory of this subreg.
1209 Otherwise, remove any memory of the entire register and
1210 all its subregs from the table. */
1211 if (REG_TICK (i
) - REG_IN_TABLE (i
) > 1
1212 || SUBREG_TICKED (i
) != REGNO (SUBREG_REG (x
)))
1213 remove_invalid_refs (i
);
1215 remove_invalid_subreg_refs (i
, SUBREG_BYTE (x
), GET_MODE (x
));
1218 REG_IN_TABLE (i
) = REG_TICK (i
);
1219 SUBREG_TICKED (i
) = REGNO (SUBREG_REG (x
));
1223 /* If X is a comparison or a COMPARE and either operand is a register
1224 that does not have a quantity, give it one. This is so that a later
1225 call to record_jump_equiv won't cause X to be assigned a different
1226 hash code and not found in the table after that call.
1228 It is not necessary to do this here, since rehash_using_reg can
1229 fix up the table later, but doing this here eliminates the need to
1230 call that expensive function in the most common case where the only
1231 use of the register is in the comparison. */
1233 if (code
== COMPARE
|| GET_RTX_CLASS (code
) == '<')
1235 if (GET_CODE (XEXP (x
, 0)) == REG
1236 && ! REGNO_QTY_VALID_P (REGNO (XEXP (x
, 0))))
1237 if (insert_regs (XEXP (x
, 0), NULL
, 0))
1239 rehash_using_reg (XEXP (x
, 0));
1243 if (GET_CODE (XEXP (x
, 1)) == REG
1244 && ! REGNO_QTY_VALID_P (REGNO (XEXP (x
, 1))))
1245 if (insert_regs (XEXP (x
, 1), NULL
, 0))
1247 rehash_using_reg (XEXP (x
, 1));
1252 fmt
= GET_RTX_FORMAT (code
);
1253 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
1255 changed
|= mention_regs (XEXP (x
, i
));
1256 else if (fmt
[i
] == 'E')
1257 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
1258 changed
|= mention_regs (XVECEXP (x
, i
, j
));
1263 /* Update the register quantities for inserting X into the hash table
1264 with a value equivalent to CLASSP.
1265 (If the class does not contain a REG, it is irrelevant.)
1266 If MODIFIED is nonzero, X is a destination; it is being modified.
1267 Note that delete_reg_equiv should be called on a register
1268 before insert_regs is done on that register with MODIFIED != 0.
1270 Nonzero value means that elements of reg_qty have changed
1271 so X's hash code may be different. */
1274 insert_regs (x
, classp
, modified
)
1276 struct table_elt
*classp
;
1279 if (GET_CODE (x
) == REG
)
1281 unsigned int regno
= REGNO (x
);
1284 /* If REGNO is in the equivalence table already but is of the
1285 wrong mode for that equivalence, don't do anything here. */
1287 qty_valid
= REGNO_QTY_VALID_P (regno
);
1290 struct qty_table_elem
*ent
= &qty_table
[REG_QTY (regno
)];
1292 if (ent
->mode
!= GET_MODE (x
))
1296 if (modified
|| ! qty_valid
)
1299 for (classp
= classp
->first_same_value
;
1301 classp
= classp
->next_same_value
)
1302 if (GET_CODE (classp
->exp
) == REG
1303 && GET_MODE (classp
->exp
) == GET_MODE (x
))
1305 make_regs_eqv (regno
, REGNO (classp
->exp
));
1309 /* Mention_regs for a SUBREG checks if REG_TICK is exactly one larger
1310 than REG_IN_TABLE to find out if there was only a single preceding
1311 invalidation - for the SUBREG - or another one, which would be
1312 for the full register. However, if we find here that REG_TICK
1313 indicates that the register is invalid, it means that it has
1314 been invalidated in a separate operation. The SUBREG might be used
1315 now (then this is a recursive call), or we might use the full REG
1316 now and a SUBREG of it later. So bump up REG_TICK so that
1317 mention_regs will do the right thing. */
1319 && REG_IN_TABLE (regno
) >= 0
1320 && REG_TICK (regno
) == REG_IN_TABLE (regno
) + 1)
1322 make_new_qty (regno
, GET_MODE (x
));
1329 /* If X is a SUBREG, we will likely be inserting the inner register in the
1330 table. If that register doesn't have an assigned quantity number at
1331 this point but does later, the insertion that we will be doing now will
1332 not be accessible because its hash code will have changed. So assign
1333 a quantity number now. */
1335 else if (GET_CODE (x
) == SUBREG
&& GET_CODE (SUBREG_REG (x
)) == REG
1336 && ! REGNO_QTY_VALID_P (REGNO (SUBREG_REG (x
))))
1338 insert_regs (SUBREG_REG (x
), NULL
, 0);
1343 return mention_regs (x
);
1346 /* Look in or update the hash table. */
1348 /* Remove table element ELT from use in the table.
1349 HASH is its hash code, made using the HASH macro.
1350 It's an argument because often that is known in advance
1351 and we save much time not recomputing it. */
1354 remove_from_table (elt
, hash
)
1355 struct table_elt
*elt
;
1361 /* Mark this element as removed. See cse_insn. */
1362 elt
->first_same_value
= 0;
1364 /* Remove the table element from its equivalence class. */
1367 struct table_elt
*prev
= elt
->prev_same_value
;
1368 struct table_elt
*next
= elt
->next_same_value
;
1371 next
->prev_same_value
= prev
;
1374 prev
->next_same_value
= next
;
1377 struct table_elt
*newfirst
= next
;
1380 next
->first_same_value
= newfirst
;
1381 next
= next
->next_same_value
;
1386 /* Remove the table element from its hash bucket. */
1389 struct table_elt
*prev
= elt
->prev_same_hash
;
1390 struct table_elt
*next
= elt
->next_same_hash
;
1393 next
->prev_same_hash
= prev
;
1396 prev
->next_same_hash
= next
;
1397 else if (table
[hash
] == elt
)
1401 /* This entry is not in the proper hash bucket. This can happen
1402 when two classes were merged by `merge_equiv_classes'. Search
1403 for the hash bucket that it heads. This happens only very
1404 rarely, so the cost is acceptable. */
1405 for (hash
= 0; hash
< HASH_SIZE
; hash
++)
1406 if (table
[hash
] == elt
)
1411 /* Remove the table element from its related-value circular chain. */
1413 if (elt
->related_value
!= 0 && elt
->related_value
!= elt
)
1415 struct table_elt
*p
= elt
->related_value
;
1417 while (p
->related_value
!= elt
)
1418 p
= p
->related_value
;
1419 p
->related_value
= elt
->related_value
;
1420 if (p
->related_value
== p
)
1421 p
->related_value
= 0;
1424 /* Now add it to the free element chain. */
1425 elt
->next_same_hash
= free_element_chain
;
1426 free_element_chain
= elt
;
1429 /* Look up X in the hash table and return its table element,
1430 or 0 if X is not in the table.
1432 MODE is the machine-mode of X, or if X is an integer constant
1433 with VOIDmode then MODE is the mode with which X will be used.
1435 Here we are satisfied to find an expression whose tree structure
1438 static struct table_elt
*
1439 lookup (x
, hash
, mode
)
1442 enum machine_mode mode
;
1444 struct table_elt
*p
;
1446 for (p
= table
[hash
]; p
; p
= p
->next_same_hash
)
1447 if (mode
== p
->mode
&& ((x
== p
->exp
&& GET_CODE (x
) == REG
)
1448 || exp_equiv_p (x
, p
->exp
, GET_CODE (x
) != REG
, 0)))
1454 /* Like `lookup' but don't care whether the table element uses invalid regs.
1455 Also ignore discrepancies in the machine mode of a register. */
1457 static struct table_elt
*
1458 lookup_for_remove (x
, hash
, mode
)
1461 enum machine_mode mode
;
1463 struct table_elt
*p
;
1465 if (GET_CODE (x
) == REG
)
1467 unsigned int regno
= REGNO (x
);
1469 /* Don't check the machine mode when comparing registers;
1470 invalidating (REG:SI 0) also invalidates (REG:DF 0). */
1471 for (p
= table
[hash
]; p
; p
= p
->next_same_hash
)
1472 if (GET_CODE (p
->exp
) == REG
1473 && REGNO (p
->exp
) == regno
)
1478 for (p
= table
[hash
]; p
; p
= p
->next_same_hash
)
1479 if (mode
== p
->mode
&& (x
== p
->exp
|| exp_equiv_p (x
, p
->exp
, 0, 0)))
1486 /* Look for an expression equivalent to X and with code CODE.
1487 If one is found, return that expression. */
1490 lookup_as_function (x
, code
)
1495 = lookup (x
, safe_hash (x
, VOIDmode
) & HASH_MASK
, GET_MODE (x
));
1497 /* If we are looking for a CONST_INT, the mode doesn't really matter, as
1498 long as we are narrowing. So if we looked in vain for a mode narrower
1499 than word_mode before, look for word_mode now. */
1500 if (p
== 0 && code
== CONST_INT
1501 && GET_MODE_SIZE (GET_MODE (x
)) < GET_MODE_SIZE (word_mode
))
1504 PUT_MODE (x
, word_mode
);
1505 p
= lookup (x
, safe_hash (x
, VOIDmode
) & HASH_MASK
, word_mode
);
1511 for (p
= p
->first_same_value
; p
; p
= p
->next_same_value
)
1512 if (GET_CODE (p
->exp
) == code
1513 /* Make sure this is a valid entry in the table. */
1514 && exp_equiv_p (p
->exp
, p
->exp
, 1, 0))
1520 /* Insert X in the hash table, assuming HASH is its hash code
1521 and CLASSP is an element of the class it should go in
1522 (or 0 if a new class should be made).
1523 It is inserted at the proper position to keep the class in
1524 the order cheapest first.
1526 MODE is the machine-mode of X, or if X is an integer constant
1527 with VOIDmode then MODE is the mode with which X will be used.
1529 For elements of equal cheapness, the most recent one
1530 goes in front, except that the first element in the list
1531 remains first unless a cheaper element is added. The order of
1532 pseudo-registers does not matter, as canon_reg will be called to
1533 find the cheapest when a register is retrieved from the table.
1535 The in_memory field in the hash table element is set to 0.
1536 The caller must set it nonzero if appropriate.
1538 You should call insert_regs (X, CLASSP, MODIFY) before calling here,
1539 and if insert_regs returns a nonzero value
1540 you must then recompute its hash code before calling here.
1542 If necessary, update table showing constant values of quantities. */
1544 #define CHEAPER(X, Y) \
1545 (preferrable ((X)->cost, (X)->regcost, (Y)->cost, (Y)->regcost) < 0)
1547 static struct table_elt
*
1548 insert (x
, classp
, hash
, mode
)
1550 struct table_elt
*classp
;
1552 enum machine_mode mode
;
1554 struct table_elt
*elt
;
1556 /* If X is a register and we haven't made a quantity for it,
1557 something is wrong. */
1558 if (GET_CODE (x
) == REG
&& ! REGNO_QTY_VALID_P (REGNO (x
)))
1561 /* If X is a hard register, show it is being put in the table. */
1562 if (GET_CODE (x
) == REG
&& REGNO (x
) < FIRST_PSEUDO_REGISTER
)
1564 unsigned int regno
= REGNO (x
);
1565 unsigned int endregno
= regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (x
));
1568 for (i
= regno
; i
< endregno
; i
++)
1569 SET_HARD_REG_BIT (hard_regs_in_table
, i
);
1572 /* Put an element for X into the right hash bucket. */
1574 elt
= free_element_chain
;
1576 free_element_chain
= elt
->next_same_hash
;
1580 elt
= (struct table_elt
*) xmalloc (sizeof (struct table_elt
));
1584 elt
->canon_exp
= NULL_RTX
;
1585 elt
->cost
= COST (x
);
1586 elt
->regcost
= approx_reg_cost (x
);
1587 elt
->next_same_value
= 0;
1588 elt
->prev_same_value
= 0;
1589 elt
->next_same_hash
= table
[hash
];
1590 elt
->prev_same_hash
= 0;
1591 elt
->related_value
= 0;
1594 elt
->is_const
= (CONSTANT_P (x
)
1595 /* GNU C++ takes advantage of this for `this'
1596 (and other const values). */
1597 || (GET_CODE (x
) == REG
1598 && RTX_UNCHANGING_P (x
)
1599 && REGNO (x
) >= FIRST_PSEUDO_REGISTER
)
1600 || fixed_base_plus_p (x
));
1603 table
[hash
]->prev_same_hash
= elt
;
1606 /* Put it into the proper value-class. */
1609 classp
= classp
->first_same_value
;
1610 if (CHEAPER (elt
, classp
))
1611 /* Insert at the head of the class */
1613 struct table_elt
*p
;
1614 elt
->next_same_value
= classp
;
1615 classp
->prev_same_value
= elt
;
1616 elt
->first_same_value
= elt
;
1618 for (p
= classp
; p
; p
= p
->next_same_value
)
1619 p
->first_same_value
= elt
;
1623 /* Insert not at head of the class. */
1624 /* Put it after the last element cheaper than X. */
1625 struct table_elt
*p
, *next
;
1627 for (p
= classp
; (next
= p
->next_same_value
) && CHEAPER (next
, elt
);
1630 /* Put it after P and before NEXT. */
1631 elt
->next_same_value
= next
;
1633 next
->prev_same_value
= elt
;
1635 elt
->prev_same_value
= p
;
1636 p
->next_same_value
= elt
;
1637 elt
->first_same_value
= classp
;
1641 elt
->first_same_value
= elt
;
1643 /* If this is a constant being set equivalent to a register or a register
1644 being set equivalent to a constant, note the constant equivalence.
1646 If this is a constant, it cannot be equivalent to a different constant,
1647 and a constant is the only thing that can be cheaper than a register. So
1648 we know the register is the head of the class (before the constant was
1651 If this is a register that is not already known equivalent to a
1652 constant, we must check the entire class.
1654 If this is a register that is already known equivalent to an insn,
1655 update the qtys `const_insn' to show that `this_insn' is the latest
1656 insn making that quantity equivalent to the constant. */
1658 if (elt
->is_const
&& classp
&& GET_CODE (classp
->exp
) == REG
1659 && GET_CODE (x
) != REG
)
1661 int exp_q
= REG_QTY (REGNO (classp
->exp
));
1662 struct qty_table_elem
*exp_ent
= &qty_table
[exp_q
];
1664 exp_ent
->const_rtx
= gen_lowpart_if_possible (exp_ent
->mode
, x
);
1665 exp_ent
->const_insn
= this_insn
;
1668 else if (GET_CODE (x
) == REG
1670 && ! qty_table
[REG_QTY (REGNO (x
))].const_rtx
1673 struct table_elt
*p
;
1675 for (p
= classp
; p
!= 0; p
= p
->next_same_value
)
1677 if (p
->is_const
&& GET_CODE (p
->exp
) != REG
)
1679 int x_q
= REG_QTY (REGNO (x
));
1680 struct qty_table_elem
*x_ent
= &qty_table
[x_q
];
1683 = gen_lowpart_if_possible (GET_MODE (x
), p
->exp
);
1684 x_ent
->const_insn
= this_insn
;
1690 else if (GET_CODE (x
) == REG
1691 && qty_table
[REG_QTY (REGNO (x
))].const_rtx
1692 && GET_MODE (x
) == qty_table
[REG_QTY (REGNO (x
))].mode
)
1693 qty_table
[REG_QTY (REGNO (x
))].const_insn
= this_insn
;
1695 /* If this is a constant with symbolic value,
1696 and it has a term with an explicit integer value,
1697 link it up with related expressions. */
1698 if (GET_CODE (x
) == CONST
)
1700 rtx subexp
= get_related_value (x
);
1702 struct table_elt
*subelt
, *subelt_prev
;
1706 /* Get the integer-free subexpression in the hash table. */
1707 subhash
= safe_hash (subexp
, mode
) & HASH_MASK
;
1708 subelt
= lookup (subexp
, subhash
, mode
);
1710 subelt
= insert (subexp
, NULL
, subhash
, mode
);
1711 /* Initialize SUBELT's circular chain if it has none. */
1712 if (subelt
->related_value
== 0)
1713 subelt
->related_value
= subelt
;
1714 /* Find the element in the circular chain that precedes SUBELT. */
1715 subelt_prev
= subelt
;
1716 while (subelt_prev
->related_value
!= subelt
)
1717 subelt_prev
= subelt_prev
->related_value
;
1718 /* Put new ELT into SUBELT's circular chain just before SUBELT.
1719 This way the element that follows SUBELT is the oldest one. */
1720 elt
->related_value
= subelt_prev
->related_value
;
1721 subelt_prev
->related_value
= elt
;
1728 /* Given two equivalence classes, CLASS1 and CLASS2, put all the entries from
1729 CLASS2 into CLASS1. This is done when we have reached an insn which makes
1730 the two classes equivalent.
1732 CLASS1 will be the surviving class; CLASS2 should not be used after this
1735 Any invalid entries in CLASS2 will not be copied. */
1738 merge_equiv_classes (class1
, class2
)
1739 struct table_elt
*class1
, *class2
;
1741 struct table_elt
*elt
, *next
, *new;
1743 /* Ensure we start with the head of the classes. */
1744 class1
= class1
->first_same_value
;
1745 class2
= class2
->first_same_value
;
1747 /* If they were already equal, forget it. */
1748 if (class1
== class2
)
1751 for (elt
= class2
; elt
; elt
= next
)
1755 enum machine_mode mode
= elt
->mode
;
1757 next
= elt
->next_same_value
;
1759 /* Remove old entry, make a new one in CLASS1's class.
1760 Don't do this for invalid entries as we cannot find their
1761 hash code (it also isn't necessary). */
1762 if (GET_CODE (exp
) == REG
|| exp_equiv_p (exp
, exp
, 1, 0))
1764 hash_arg_in_memory
= 0;
1765 hash
= HASH (exp
, mode
);
1767 if (GET_CODE (exp
) == REG
)
1768 delete_reg_equiv (REGNO (exp
));
1770 remove_from_table (elt
, hash
);
1772 if (insert_regs (exp
, class1
, 0))
1774 rehash_using_reg (exp
);
1775 hash
= HASH (exp
, mode
);
1777 new = insert (exp
, class1
, hash
, mode
);
1778 new->in_memory
= hash_arg_in_memory
;
1783 /* Flush the entire hash table. */
1789 struct table_elt
*p
;
1791 for (i
= 0; i
< HASH_SIZE
; i
++)
1792 for (p
= table
[i
]; p
; p
= table
[i
])
1794 /* Note that invalidate can remove elements
1795 after P in the current hash chain. */
1796 if (GET_CODE (p
->exp
) == REG
)
1797 invalidate (p
->exp
, p
->mode
);
1799 remove_from_table (p
, i
);
1803 /* Function called for each rtx to check whether true dependence exist. */
1804 struct check_dependence_data
1806 enum machine_mode mode
;
1811 check_dependence (x
, data
)
1815 struct check_dependence_data
*d
= (struct check_dependence_data
*) data
;
1816 if (*x
&& GET_CODE (*x
) == MEM
)
1817 return true_dependence (d
->exp
, d
->mode
, *x
, cse_rtx_varies_p
);
1822 /* Remove from the hash table, or mark as invalid, all expressions whose
1823 values could be altered by storing in X. X is a register, a subreg, or
1824 a memory reference with nonvarying address (because, when a memory
1825 reference with a varying address is stored in, all memory references are
1826 removed by invalidate_memory so specific invalidation is superfluous).
1827 FULL_MODE, if not VOIDmode, indicates that this much should be
1828 invalidated instead of just the amount indicated by the mode of X. This
1829 is only used for bitfield stores into memory.
1831 A nonvarying address may be just a register or just a symbol reference,
1832 or it may be either of those plus a numeric offset. */
1835 invalidate (x
, full_mode
)
1837 enum machine_mode full_mode
;
1840 struct table_elt
*p
;
1842 switch (GET_CODE (x
))
1846 /* If X is a register, dependencies on its contents are recorded
1847 through the qty number mechanism. Just change the qty number of
1848 the register, mark it as invalid for expressions that refer to it,
1849 and remove it itself. */
1850 unsigned int regno
= REGNO (x
);
1851 unsigned int hash
= HASH (x
, GET_MODE (x
));
1853 /* Remove REGNO from any quantity list it might be on and indicate
1854 that its value might have changed. If it is a pseudo, remove its
1855 entry from the hash table.
1857 For a hard register, we do the first two actions above for any
1858 additional hard registers corresponding to X. Then, if any of these
1859 registers are in the table, we must remove any REG entries that
1860 overlap these registers. */
1862 delete_reg_equiv (regno
);
1864 SUBREG_TICKED (regno
) = -1;
1866 if (regno
>= FIRST_PSEUDO_REGISTER
)
1868 /* Because a register can be referenced in more than one mode,
1869 we might have to remove more than one table entry. */
1870 struct table_elt
*elt
;
1872 while ((elt
= lookup_for_remove (x
, hash
, GET_MODE (x
))))
1873 remove_from_table (elt
, hash
);
1877 HOST_WIDE_INT in_table
1878 = TEST_HARD_REG_BIT (hard_regs_in_table
, regno
);
1879 unsigned int endregno
1880 = regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (x
));
1881 unsigned int tregno
, tendregno
, rn
;
1882 struct table_elt
*p
, *next
;
1884 CLEAR_HARD_REG_BIT (hard_regs_in_table
, regno
);
1886 for (rn
= regno
+ 1; rn
< endregno
; rn
++)
1888 in_table
|= TEST_HARD_REG_BIT (hard_regs_in_table
, rn
);
1889 CLEAR_HARD_REG_BIT (hard_regs_in_table
, rn
);
1890 delete_reg_equiv (rn
);
1892 SUBREG_TICKED (rn
) = -1;
1896 for (hash
= 0; hash
< HASH_SIZE
; hash
++)
1897 for (p
= table
[hash
]; p
; p
= next
)
1899 next
= p
->next_same_hash
;
1901 if (GET_CODE (p
->exp
) != REG
1902 || REGNO (p
->exp
) >= FIRST_PSEUDO_REGISTER
)
1905 tregno
= REGNO (p
->exp
);
1907 = tregno
+ HARD_REGNO_NREGS (tregno
, GET_MODE (p
->exp
));
1908 if (tendregno
> regno
&& tregno
< endregno
)
1909 remove_from_table (p
, hash
);
1916 invalidate (SUBREG_REG (x
), VOIDmode
);
1920 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; --i
)
1921 invalidate (XVECEXP (x
, 0, i
), VOIDmode
);
1925 /* This is part of a disjoint return value; extract the location in
1926 question ignoring the offset. */
1927 invalidate (XEXP (x
, 0), VOIDmode
);
1931 /* Calculate the canonical version of X here so that
1932 true_dependence doesn't generate new RTL for X on each call. */
1935 /* Remove all hash table elements that refer to overlapping pieces of
1937 if (full_mode
== VOIDmode
)
1938 full_mode
= GET_MODE (x
);
1940 for (i
= 0; i
< HASH_SIZE
; i
++)
1942 struct table_elt
*next
;
1944 for (p
= table
[i
]; p
; p
= next
)
1946 next
= p
->next_same_hash
;
1949 struct check_dependence_data d
;
1951 /* Just canonicalize the expression once;
1952 otherwise each time we call invalidate
1953 true_dependence will canonicalize the
1954 expression again. */
1956 p
->canon_exp
= canon_rtx (p
->exp
);
1959 if (for_each_rtx (&p
->canon_exp
, check_dependence
, &d
))
1960 remove_from_table (p
, i
);
1971 /* Remove all expressions that refer to register REGNO,
1972 since they are already invalid, and we are about to
1973 mark that register valid again and don't want the old
1974 expressions to reappear as valid. */
1977 remove_invalid_refs (regno
)
1981 struct table_elt
*p
, *next
;
1983 for (i
= 0; i
< HASH_SIZE
; i
++)
1984 for (p
= table
[i
]; p
; p
= next
)
1986 next
= p
->next_same_hash
;
1987 if (GET_CODE (p
->exp
) != REG
1988 && refers_to_regno_p (regno
, regno
+ 1, p
->exp
, (rtx
*) 0))
1989 remove_from_table (p
, i
);
1993 /* Likewise for a subreg with subreg_reg REGNO, subreg_byte OFFSET,
1996 remove_invalid_subreg_refs (regno
, offset
, mode
)
1998 unsigned int offset
;
1999 enum machine_mode mode
;
2002 struct table_elt
*p
, *next
;
2003 unsigned int end
= offset
+ (GET_MODE_SIZE (mode
) - 1);
2005 for (i
= 0; i
< HASH_SIZE
; i
++)
2006 for (p
= table
[i
]; p
; p
= next
)
2009 next
= p
->next_same_hash
;
2011 if (GET_CODE (exp
) != REG
2012 && (GET_CODE (exp
) != SUBREG
2013 || GET_CODE (SUBREG_REG (exp
)) != REG
2014 || REGNO (SUBREG_REG (exp
)) != regno
2015 || (((SUBREG_BYTE (exp
)
2016 + (GET_MODE_SIZE (GET_MODE (exp
)) - 1)) >= offset
)
2017 && SUBREG_BYTE (exp
) <= end
))
2018 && refers_to_regno_p (regno
, regno
+ 1, p
->exp
, (rtx
*) 0))
2019 remove_from_table (p
, i
);
2023 /* Recompute the hash codes of any valid entries in the hash table that
2024 reference X, if X is a register, or SUBREG_REG (X) if X is a SUBREG.
2026 This is called when we make a jump equivalence. */
2029 rehash_using_reg (x
)
2033 struct table_elt
*p
, *next
;
2036 if (GET_CODE (x
) == SUBREG
)
2039 /* If X is not a register or if the register is known not to be in any
2040 valid entries in the table, we have no work to do. */
2042 if (GET_CODE (x
) != REG
2043 || REG_IN_TABLE (REGNO (x
)) < 0
2044 || REG_IN_TABLE (REGNO (x
)) != REG_TICK (REGNO (x
)))
2047 /* Scan all hash chains looking for valid entries that mention X.
2048 If we find one and it is in the wrong hash chain, move it. We can skip
2049 objects that are registers, since they are handled specially. */
2051 for (i
= 0; i
< HASH_SIZE
; i
++)
2052 for (p
= table
[i
]; p
; p
= next
)
2054 next
= p
->next_same_hash
;
2055 if (GET_CODE (p
->exp
) != REG
&& reg_mentioned_p (x
, p
->exp
)
2056 && exp_equiv_p (p
->exp
, p
->exp
, 1, 0)
2057 && i
!= (hash
= safe_hash (p
->exp
, p
->mode
) & HASH_MASK
))
2059 if (p
->next_same_hash
)
2060 p
->next_same_hash
->prev_same_hash
= p
->prev_same_hash
;
2062 if (p
->prev_same_hash
)
2063 p
->prev_same_hash
->next_same_hash
= p
->next_same_hash
;
2065 table
[i
] = p
->next_same_hash
;
2067 p
->next_same_hash
= table
[hash
];
2068 p
->prev_same_hash
= 0;
2070 table
[hash
]->prev_same_hash
= p
;
2076 /* Remove from the hash table any expression that is a call-clobbered
2077 register. Also update their TICK values. */
2080 invalidate_for_call ()
2082 unsigned int regno
, endregno
;
2085 struct table_elt
*p
, *next
;
2088 /* Go through all the hard registers. For each that is clobbered in
2089 a CALL_INSN, remove the register from quantity chains and update
2090 reg_tick if defined. Also see if any of these registers is currently
2093 for (regno
= 0; regno
< FIRST_PSEUDO_REGISTER
; regno
++)
2094 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, regno
))
2096 delete_reg_equiv (regno
);
2097 if (REG_TICK (regno
) >= 0)
2100 SUBREG_TICKED (regno
) = -1;
2103 in_table
|= (TEST_HARD_REG_BIT (hard_regs_in_table
, regno
) != 0);
2106 /* In the case where we have no call-clobbered hard registers in the
2107 table, we are done. Otherwise, scan the table and remove any
2108 entry that overlaps a call-clobbered register. */
2111 for (hash
= 0; hash
< HASH_SIZE
; hash
++)
2112 for (p
= table
[hash
]; p
; p
= next
)
2114 next
= p
->next_same_hash
;
2116 if (GET_CODE (p
->exp
) != REG
2117 || REGNO (p
->exp
) >= FIRST_PSEUDO_REGISTER
)
2120 regno
= REGNO (p
->exp
);
2121 endregno
= regno
+ HARD_REGNO_NREGS (regno
, GET_MODE (p
->exp
));
2123 for (i
= regno
; i
< endregno
; i
++)
2124 if (TEST_HARD_REG_BIT (regs_invalidated_by_call
, i
))
2126 remove_from_table (p
, hash
);
2132 /* Given an expression X of type CONST,
2133 and ELT which is its table entry (or 0 if it
2134 is not in the hash table),
2135 return an alternate expression for X as a register plus integer.
2136 If none can be found, return 0. */
2139 use_related_value (x
, elt
)
2141 struct table_elt
*elt
;
2143 struct table_elt
*relt
= 0;
2144 struct table_elt
*p
, *q
;
2145 HOST_WIDE_INT offset
;
2147 /* First, is there anything related known?
2148 If we have a table element, we can tell from that.
2149 Otherwise, must look it up. */
2151 if (elt
!= 0 && elt
->related_value
!= 0)
2153 else if (elt
== 0 && GET_CODE (x
) == CONST
)
2155 rtx subexp
= get_related_value (x
);
2157 relt
= lookup (subexp
,
2158 safe_hash (subexp
, GET_MODE (subexp
)) & HASH_MASK
,
2165 /* Search all related table entries for one that has an
2166 equivalent register. */
2171 /* This loop is strange in that it is executed in two different cases.
2172 The first is when X is already in the table. Then it is searching
2173 the RELATED_VALUE list of X's class (RELT). The second case is when
2174 X is not in the table. Then RELT points to a class for the related
2177 Ensure that, whatever case we are in, that we ignore classes that have
2178 the same value as X. */
2180 if (rtx_equal_p (x
, p
->exp
))
2183 for (q
= p
->first_same_value
; q
; q
= q
->next_same_value
)
2184 if (GET_CODE (q
->exp
) == REG
)
2190 p
= p
->related_value
;
2192 /* We went all the way around, so there is nothing to be found.
2193 Alternatively, perhaps RELT was in the table for some other reason
2194 and it has no related values recorded. */
2195 if (p
== relt
|| p
== 0)
2202 offset
= (get_integer_term (x
) - get_integer_term (p
->exp
));
2203 /* Note: OFFSET may be 0 if P->xexp and X are related by commutativity. */
2204 return plus_constant (q
->exp
, offset
);
2207 /* Hash a string. Just add its bytes up. */
2208 static inline unsigned
2209 canon_hash_string (ps
)
2213 const unsigned char *p
= (const unsigned char *) ps
;
2222 /* Hash an rtx. We are careful to make sure the value is never negative.
2223 Equivalent registers hash identically.
2224 MODE is used in hashing for CONST_INTs only;
2225 otherwise the mode of X is used.
2227 Store 1 in do_not_record if any subexpression is volatile.
2229 Store 1 in hash_arg_in_memory if X contains a MEM rtx
2230 which does not have the RTX_UNCHANGING_P bit set.
2232 Note that cse_insn knows that the hash code of a MEM expression
2233 is just (int) MEM plus the hash code of the address. */
2236 canon_hash (x
, mode
)
2238 enum machine_mode mode
;
2245 /* repeat is used to turn tail-recursion into iteration. */
2250 code
= GET_CODE (x
);
2255 unsigned int regno
= REGNO (x
);
2258 /* On some machines, we can't record any non-fixed hard register,
2259 because extending its life will cause reload problems. We
2260 consider ap, fp, sp, gp to be fixed for this purpose.
2262 We also consider CCmode registers to be fixed for this purpose;
2263 failure to do so leads to failure to simplify 0<100 type of
2266 On all machines, we can't record any global registers.
2267 Nor should we record any register that is in a small
2268 class, as defined by CLASS_LIKELY_SPILLED_P. */
2270 if (regno
>= FIRST_PSEUDO_REGISTER
)
2272 else if (x
== frame_pointer_rtx
2273 || x
== hard_frame_pointer_rtx
2274 || x
== arg_pointer_rtx
2275 || x
== stack_pointer_rtx
2276 || x
== pic_offset_table_rtx
)
2278 else if (global_regs
[regno
])
2280 else if (fixed_regs
[regno
])
2282 else if (GET_MODE_CLASS (GET_MODE (x
)) == MODE_CC
)
2284 else if (SMALL_REGISTER_CLASSES
)
2286 else if (CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (regno
)))
2297 hash
+= ((unsigned) REG
<< 7) + (unsigned) REG_QTY (regno
);
2301 /* We handle SUBREG of a REG specially because the underlying
2302 reg changes its hash value with every value change; we don't
2303 want to have to forget unrelated subregs when one subreg changes. */
2306 if (GET_CODE (SUBREG_REG (x
)) == REG
)
2308 hash
+= (((unsigned) SUBREG
<< 7)
2309 + REGNO (SUBREG_REG (x
))
2310 + (SUBREG_BYTE (x
) / UNITS_PER_WORD
));
2318 unsigned HOST_WIDE_INT tem
= INTVAL (x
);
2319 hash
+= ((unsigned) CONST_INT
<< 7) + (unsigned) mode
+ tem
;
2324 /* This is like the general case, except that it only counts
2325 the integers representing the constant. */
2326 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
);
2327 if (GET_MODE (x
) != VOIDmode
)
2328 hash
+= real_hash (CONST_DOUBLE_REAL_VALUE (x
));
2330 hash
+= ((unsigned) CONST_DOUBLE_LOW (x
)
2331 + (unsigned) CONST_DOUBLE_HIGH (x
));
2339 units
= CONST_VECTOR_NUNITS (x
);
2341 for (i
= 0; i
< units
; ++i
)
2343 elt
= CONST_VECTOR_ELT (x
, i
);
2344 hash
+= canon_hash (elt
, GET_MODE (elt
));
2350 /* Assume there is only one rtx object for any given label. */
2352 hash
+= ((unsigned) LABEL_REF
<< 7) + (unsigned long) XEXP (x
, 0);
2356 hash
+= ((unsigned) SYMBOL_REF
<< 7) + (unsigned long) XSTR (x
, 0);
2360 /* We don't record if marked volatile or if BLKmode since we don't
2361 know the size of the move. */
2362 if (MEM_VOLATILE_P (x
) || GET_MODE (x
) == BLKmode
)
2367 if (! RTX_UNCHANGING_P (x
) || fixed_base_plus_p (XEXP (x
, 0)))
2368 hash_arg_in_memory
= 1;
2370 /* Now that we have already found this special case,
2371 might as well speed it up as much as possible. */
2372 hash
+= (unsigned) MEM
;
2377 /* A USE that mentions non-volatile memory needs special
2378 handling since the MEM may be BLKmode which normally
2379 prevents an entry from being made. Pure calls are
2380 marked by a USE which mentions BLKmode memory. */
2381 if (GET_CODE (XEXP (x
, 0)) == MEM
2382 && ! MEM_VOLATILE_P (XEXP (x
, 0)))
2384 hash
+= (unsigned) USE
;
2387 if (! RTX_UNCHANGING_P (x
) || fixed_base_plus_p (XEXP (x
, 0)))
2388 hash_arg_in_memory
= 1;
2390 /* Now that we have already found this special case,
2391 might as well speed it up as much as possible. */
2392 hash
+= (unsigned) MEM
;
2407 case UNSPEC_VOLATILE
:
2412 if (MEM_VOLATILE_P (x
))
2419 /* We don't want to take the filename and line into account. */
2420 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
)
2421 + canon_hash_string (ASM_OPERANDS_TEMPLATE (x
))
2422 + canon_hash_string (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
))
2423 + (unsigned) ASM_OPERANDS_OUTPUT_IDX (x
);
2425 if (ASM_OPERANDS_INPUT_LENGTH (x
))
2427 for (i
= 1; i
< ASM_OPERANDS_INPUT_LENGTH (x
); i
++)
2429 hash
+= (canon_hash (ASM_OPERANDS_INPUT (x
, i
),
2430 GET_MODE (ASM_OPERANDS_INPUT (x
, i
)))
2431 + canon_hash_string (ASM_OPERANDS_INPUT_CONSTRAINT
2435 hash
+= canon_hash_string (ASM_OPERANDS_INPUT_CONSTRAINT (x
, 0));
2436 x
= ASM_OPERANDS_INPUT (x
, 0);
2437 mode
= GET_MODE (x
);
2449 i
= GET_RTX_LENGTH (code
) - 1;
2450 hash
+= (unsigned) code
+ (unsigned) GET_MODE (x
);
2451 fmt
= GET_RTX_FORMAT (code
);
2456 rtx tem
= XEXP (x
, i
);
2458 /* If we are about to do the last recursive call
2459 needed at this level, change it into iteration.
2460 This function is called enough to be worth it. */
2466 hash
+= canon_hash (tem
, 0);
2468 else if (fmt
[i
] == 'E')
2469 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2470 hash
+= canon_hash (XVECEXP (x
, i
, j
), 0);
2471 else if (fmt
[i
] == 's')
2472 hash
+= canon_hash_string (XSTR (x
, i
));
2473 else if (fmt
[i
] == 'i')
2475 unsigned tem
= XINT (x
, i
);
2478 else if (fmt
[i
] == '0' || fmt
[i
] == 't')
2487 /* Like canon_hash but with no side effects. */
2492 enum machine_mode mode
;
2494 int save_do_not_record
= do_not_record
;
2495 int save_hash_arg_in_memory
= hash_arg_in_memory
;
2496 unsigned hash
= canon_hash (x
, mode
);
2497 hash_arg_in_memory
= save_hash_arg_in_memory
;
2498 do_not_record
= save_do_not_record
;
2502 /* Return 1 iff X and Y would canonicalize into the same thing,
2503 without actually constructing the canonicalization of either one.
2504 If VALIDATE is nonzero,
2505 we assume X is an expression being processed from the rtl
2506 and Y was found in the hash table. We check register refs
2507 in Y for being marked as valid.
2509 If EQUAL_VALUES is nonzero, we allow a register to match a constant value
2510 that is known to be in the register. Ordinarily, we don't allow them
2511 to match, because letting them match would cause unpredictable results
2512 in all the places that search a hash table chain for an equivalent
2513 for a given value. A possible equivalent that has different structure
2514 has its hash code computed from different data. Whether the hash code
2515 is the same as that of the given value is pure luck. */
2518 exp_equiv_p (x
, y
, validate
, equal_values
)
2527 /* Note: it is incorrect to assume an expression is equivalent to itself
2528 if VALIDATE is nonzero. */
2529 if (x
== y
&& !validate
)
2531 if (x
== 0 || y
== 0)
2534 code
= GET_CODE (x
);
2535 if (code
!= GET_CODE (y
))
2540 /* If X is a constant and Y is a register or vice versa, they may be
2541 equivalent. We only have to validate if Y is a register. */
2542 if (CONSTANT_P (x
) && GET_CODE (y
) == REG
2543 && REGNO_QTY_VALID_P (REGNO (y
)))
2545 int y_q
= REG_QTY (REGNO (y
));
2546 struct qty_table_elem
*y_ent
= &qty_table
[y_q
];
2548 if (GET_MODE (y
) == y_ent
->mode
2549 && rtx_equal_p (x
, y_ent
->const_rtx
)
2550 && (! validate
|| REG_IN_TABLE (REGNO (y
)) == REG_TICK (REGNO (y
))))
2554 if (CONSTANT_P (y
) && code
== REG
2555 && REGNO_QTY_VALID_P (REGNO (x
)))
2557 int x_q
= REG_QTY (REGNO (x
));
2558 struct qty_table_elem
*x_ent
= &qty_table
[x_q
];
2560 if (GET_MODE (x
) == x_ent
->mode
2561 && rtx_equal_p (y
, x_ent
->const_rtx
))
2568 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. */
2569 if (GET_MODE (x
) != GET_MODE (y
))
2580 return XEXP (x
, 0) == XEXP (y
, 0);
2583 return XSTR (x
, 0) == XSTR (y
, 0);
2587 unsigned int regno
= REGNO (y
);
2588 unsigned int endregno
2589 = regno
+ (regno
>= FIRST_PSEUDO_REGISTER
? 1
2590 : HARD_REGNO_NREGS (regno
, GET_MODE (y
)));
2593 /* If the quantities are not the same, the expressions are not
2594 equivalent. If there are and we are not to validate, they
2595 are equivalent. Otherwise, ensure all regs are up-to-date. */
2597 if (REG_QTY (REGNO (x
)) != REG_QTY (regno
))
2603 for (i
= regno
; i
< endregno
; i
++)
2604 if (REG_IN_TABLE (i
) != REG_TICK (i
))
2610 /* For commutative operations, check both orders. */
2618 return ((exp_equiv_p (XEXP (x
, 0), XEXP (y
, 0), validate
, equal_values
)
2619 && exp_equiv_p (XEXP (x
, 1), XEXP (y
, 1),
2620 validate
, equal_values
))
2621 || (exp_equiv_p (XEXP (x
, 0), XEXP (y
, 1),
2622 validate
, equal_values
)
2623 && exp_equiv_p (XEXP (x
, 1), XEXP (y
, 0),
2624 validate
, equal_values
)));
2627 /* We don't use the generic code below because we want to
2628 disregard filename and line numbers. */
2630 /* A volatile asm isn't equivalent to any other. */
2631 if (MEM_VOLATILE_P (x
) || MEM_VOLATILE_P (y
))
2634 if (GET_MODE (x
) != GET_MODE (y
)
2635 || strcmp (ASM_OPERANDS_TEMPLATE (x
), ASM_OPERANDS_TEMPLATE (y
))
2636 || strcmp (ASM_OPERANDS_OUTPUT_CONSTRAINT (x
),
2637 ASM_OPERANDS_OUTPUT_CONSTRAINT (y
))
2638 || ASM_OPERANDS_OUTPUT_IDX (x
) != ASM_OPERANDS_OUTPUT_IDX (y
)
2639 || ASM_OPERANDS_INPUT_LENGTH (x
) != ASM_OPERANDS_INPUT_LENGTH (y
))
2642 if (ASM_OPERANDS_INPUT_LENGTH (x
))
2644 for (i
= ASM_OPERANDS_INPUT_LENGTH (x
) - 1; i
>= 0; i
--)
2645 if (! exp_equiv_p (ASM_OPERANDS_INPUT (x
, i
),
2646 ASM_OPERANDS_INPUT (y
, i
),
2647 validate
, equal_values
)
2648 || strcmp (ASM_OPERANDS_INPUT_CONSTRAINT (x
, i
),
2649 ASM_OPERANDS_INPUT_CONSTRAINT (y
, i
)))
2659 /* Compare the elements. If any pair of corresponding elements
2660 fail to match, return 0 for the whole things. */
2662 fmt
= GET_RTX_FORMAT (code
);
2663 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2668 if (! exp_equiv_p (XEXP (x
, i
), XEXP (y
, i
), validate
, equal_values
))
2673 if (XVECLEN (x
, i
) != XVECLEN (y
, i
))
2675 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2676 if (! exp_equiv_p (XVECEXP (x
, i
, j
), XVECEXP (y
, i
, j
),
2677 validate
, equal_values
))
2682 if (strcmp (XSTR (x
, i
), XSTR (y
, i
)))
2687 if (XINT (x
, i
) != XINT (y
, i
))
2692 if (XWINT (x
, i
) != XWINT (y
, i
))
2708 /* Return 1 if X has a value that can vary even between two
2709 executions of the program. 0 means X can be compared reliably
2710 against certain constants or near-constants. */
2713 cse_rtx_varies_p (x
, from_alias
)
2717 /* We need not check for X and the equivalence class being of the same
2718 mode because if X is equivalent to a constant in some mode, it
2719 doesn't vary in any mode. */
2721 if (GET_CODE (x
) == REG
2722 && REGNO_QTY_VALID_P (REGNO (x
)))
2724 int x_q
= REG_QTY (REGNO (x
));
2725 struct qty_table_elem
*x_ent
= &qty_table
[x_q
];
2727 if (GET_MODE (x
) == x_ent
->mode
2728 && x_ent
->const_rtx
!= NULL_RTX
)
2732 if (GET_CODE (x
) == PLUS
2733 && GET_CODE (XEXP (x
, 1)) == CONST_INT
2734 && GET_CODE (XEXP (x
, 0)) == REG
2735 && REGNO_QTY_VALID_P (REGNO (XEXP (x
, 0))))
2737 int x0_q
= REG_QTY (REGNO (XEXP (x
, 0)));
2738 struct qty_table_elem
*x0_ent
= &qty_table
[x0_q
];
2740 if ((GET_MODE (XEXP (x
, 0)) == x0_ent
->mode
)
2741 && x0_ent
->const_rtx
!= NULL_RTX
)
2745 /* This can happen as the result of virtual register instantiation, if
2746 the initial constant is too large to be a valid address. This gives
2747 us a three instruction sequence, load large offset into a register,
2748 load fp minus a constant into a register, then a MEM which is the
2749 sum of the two `constant' registers. */
2750 if (GET_CODE (x
) == PLUS
2751 && GET_CODE (XEXP (x
, 0)) == REG
2752 && GET_CODE (XEXP (x
, 1)) == REG
2753 && REGNO_QTY_VALID_P (REGNO (XEXP (x
, 0)))
2754 && REGNO_QTY_VALID_P (REGNO (XEXP (x
, 1))))
2756 int x0_q
= REG_QTY (REGNO (XEXP (x
, 0)));
2757 int x1_q
= REG_QTY (REGNO (XEXP (x
, 1)));
2758 struct qty_table_elem
*x0_ent
= &qty_table
[x0_q
];
2759 struct qty_table_elem
*x1_ent
= &qty_table
[x1_q
];
2761 if ((GET_MODE (XEXP (x
, 0)) == x0_ent
->mode
)
2762 && x0_ent
->const_rtx
!= NULL_RTX
2763 && (GET_MODE (XEXP (x
, 1)) == x1_ent
->mode
)
2764 && x1_ent
->const_rtx
!= NULL_RTX
)
2768 return rtx_varies_p (x
, from_alias
);
2771 /* Canonicalize an expression:
2772 replace each register reference inside it
2773 with the "oldest" equivalent register.
2775 If INSN is nonzero and we are replacing a pseudo with a hard register
2776 or vice versa, validate_change is used to ensure that INSN remains valid
2777 after we make our substitution. The calls are made with IN_GROUP nonzero
2778 so apply_change_group must be called upon the outermost return from this
2779 function (unless INSN is zero). The result of apply_change_group can
2780 generally be discarded since the changes we are making are optional. */
2794 code
= GET_CODE (x
);
2813 struct qty_table_elem
*ent
;
2815 /* Never replace a hard reg, because hard regs can appear
2816 in more than one machine mode, and we must preserve the mode
2817 of each occurrence. Also, some hard regs appear in
2818 MEMs that are shared and mustn't be altered. Don't try to
2819 replace any reg that maps to a reg of class NO_REGS. */
2820 if (REGNO (x
) < FIRST_PSEUDO_REGISTER
2821 || ! REGNO_QTY_VALID_P (REGNO (x
)))
2824 q
= REG_QTY (REGNO (x
));
2825 ent
= &qty_table
[q
];
2826 first
= ent
->first_reg
;
2827 return (first
>= FIRST_PSEUDO_REGISTER
? regno_reg_rtx
[first
]
2828 : REGNO_REG_CLASS (first
) == NO_REGS
? x
2829 : gen_rtx_REG (ent
->mode
, first
));
2836 fmt
= GET_RTX_FORMAT (code
);
2837 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
2843 rtx
new = canon_reg (XEXP (x
, i
), insn
);
2846 /* If replacing pseudo with hard reg or vice versa, ensure the
2847 insn remains valid. Likewise if the insn has MATCH_DUPs. */
2848 if (insn
!= 0 && new != 0
2849 && GET_CODE (new) == REG
&& GET_CODE (XEXP (x
, i
)) == REG
2850 && (((REGNO (new) < FIRST_PSEUDO_REGISTER
)
2851 != (REGNO (XEXP (x
, i
)) < FIRST_PSEUDO_REGISTER
))
2852 || (insn_code
= recog_memoized (insn
)) < 0
2853 || insn_data
[insn_code
].n_dups
> 0))
2854 validate_change (insn
, &XEXP (x
, i
), new, 1);
2858 else if (fmt
[i
] == 'E')
2859 for (j
= 0; j
< XVECLEN (x
, i
); j
++)
2860 XVECEXP (x
, i
, j
) = canon_reg (XVECEXP (x
, i
, j
), insn
);
2866 /* LOC is a location within INSN that is an operand address (the contents of
2867 a MEM). Find the best equivalent address to use that is valid for this
2870 On most CISC machines, complicated address modes are costly, and rtx_cost
2871 is a good approximation for that cost. However, most RISC machines have
2872 only a few (usually only one) memory reference formats. If an address is
2873 valid at all, it is often just as cheap as any other address. Hence, for
2874 RISC machines, we use `address_cost' to compare the costs of various
2875 addresses. For two addresses of equal cost, choose the one with the
2876 highest `rtx_cost' value as that has the potential of eliminating the
2877 most insns. For equal costs, we choose the first in the equivalence
2878 class. Note that we ignore the fact that pseudo registers are cheaper than
2879 hard registers here because we would also prefer the pseudo registers. */
2882 find_best_addr (insn
, loc
, mode
)
2885 enum machine_mode mode
;
2887 struct table_elt
*elt
;
2889 struct table_elt
*p
;
2890 int found_better
= 1;
2891 int save_do_not_record
= do_not_record
;
2892 int save_hash_arg_in_memory
= hash_arg_in_memory
;
2897 /* Do not try to replace constant addresses or addresses of local and
2898 argument slots. These MEM expressions are made only once and inserted
2899 in many instructions, as well as being used to control symbol table
2900 output. It is not safe to clobber them.
2902 There are some uncommon cases where the address is already in a register
2903 for some reason, but we cannot take advantage of that because we have
2904 no easy way to unshare the MEM. In addition, looking up all stack
2905 addresses is costly. */
2906 if ((GET_CODE (addr
) == PLUS
2907 && GET_CODE (XEXP (addr
, 0)) == REG
2908 && GET_CODE (XEXP (addr
, 1)) == CONST_INT
2909 && (regno
= REGNO (XEXP (addr
, 0)),
2910 regno
== FRAME_POINTER_REGNUM
|| regno
== HARD_FRAME_POINTER_REGNUM
2911 || regno
== ARG_POINTER_REGNUM
))
2912 || (GET_CODE (addr
) == REG
2913 && (regno
= REGNO (addr
), regno
== FRAME_POINTER_REGNUM
2914 || regno
== HARD_FRAME_POINTER_REGNUM
2915 || regno
== ARG_POINTER_REGNUM
))
2916 || GET_CODE (addr
) == ADDRESSOF
2917 || CONSTANT_ADDRESS_P (addr
))
2920 /* If this address is not simply a register, try to fold it. This will
2921 sometimes simplify the expression. Many simplifications
2922 will not be valid, but some, usually applying the associative rule, will
2923 be valid and produce better code. */
2924 if (GET_CODE (addr
) != REG
)
2926 rtx folded
= fold_rtx (copy_rtx (addr
), NULL_RTX
);
2927 int addr_folded_cost
= address_cost (folded
, mode
);
2928 int addr_cost
= address_cost (addr
, mode
);
2930 if ((addr_folded_cost
< addr_cost
2931 || (addr_folded_cost
== addr_cost
2932 /* ??? The rtx_cost comparison is left over from an older
2933 version of this code. It is probably no longer helpful. */
2934 && (rtx_cost (folded
, MEM
) > rtx_cost (addr
, MEM
)
2935 || approx_reg_cost (folded
) < approx_reg_cost (addr
))))
2936 && validate_change (insn
, loc
, folded
, 0))
2940 /* If this address is not in the hash table, we can't look for equivalences
2941 of the whole address. Also, ignore if volatile. */
2944 hash
= HASH (addr
, Pmode
);
2945 addr_volatile
= do_not_record
;
2946 do_not_record
= save_do_not_record
;
2947 hash_arg_in_memory
= save_hash_arg_in_memory
;
2952 elt
= lookup (addr
, hash
, Pmode
);
2956 /* We need to find the best (under the criteria documented above) entry
2957 in the class that is valid. We use the `flag' field to indicate
2958 choices that were invalid and iterate until we can't find a better
2959 one that hasn't already been tried. */
2961 for (p
= elt
->first_same_value
; p
; p
= p
->next_same_value
)
2964 while (found_better
)
2966 int best_addr_cost
= address_cost (*loc
, mode
);
2967 int best_rtx_cost
= (elt
->cost
+ 1) >> 1;
2969 struct table_elt
*best_elt
= elt
;
2972 for (p
= elt
->first_same_value
; p
; p
= p
->next_same_value
)
2975 if ((GET_CODE (p
->exp
) == REG
2976 || exp_equiv_p (p
->exp
, p
->exp
, 1, 0))
2977 && ((exp_cost
= address_cost (p
->exp
, mode
)) < best_addr_cost
2978 || (exp_cost
== best_addr_cost
2979 && ((p
->cost
+ 1) >> 1) > best_rtx_cost
)))
2982 best_addr_cost
= exp_cost
;
2983 best_rtx_cost
= (p
->cost
+ 1) >> 1;
2990 if (validate_change (insn
, loc
,
2991 canon_reg (copy_rtx (best_elt
->exp
),
3000 /* If the address is a binary operation with the first operand a register
3001 and the second a constant, do the same as above, but looking for
3002 equivalences of the register. Then try to simplify before checking for
3003 the best address to use. This catches a few cases: First is when we
3004 have REG+const and the register is another REG+const. We can often merge
3005 the constants and eliminate one insn and one register. It may also be
3006 that a machine has a cheap REG+REG+const. Finally, this improves the
3007 code on the Alpha for unaligned byte stores. */
3009 if (flag_expensive_optimizations
3010 && (GET_RTX_CLASS (GET_CODE (*loc
)) == '2'
3011 || GET_RTX_CLASS (GET_CODE (*loc
)) == 'c')
3012 && GET_CODE (XEXP (*loc
, 0)) == REG
3013 && GET_CODE (XEXP (*loc
, 1)) == CONST_INT
)
3015 rtx c
= XEXP (*loc
, 1);
3018 hash
= HASH (XEXP (*loc
, 0), Pmode
);
3019 do_not_record
= save_do_not_record
;
3020 hash_arg_in_memory
= save_hash_arg_in_memory
;
3022 elt
= lookup (XEXP (*loc
, 0), hash
, Pmode
);
3026 /* We need to find the best (under the criteria documented above) entry
3027 in the class that is valid. We use the `flag' field to indicate
3028 choices that were invalid and iterate until we can't find a better
3029 one that hasn't already been tried. */
3031 for (p
= elt
->first_same_value
; p
; p
= p
->next_same_value
)
3034 while (found_better
)
3036 int best_addr_cost
= address_cost (*loc
, mode
);
3037 int best_rtx_cost
= (COST (*loc
) + 1) >> 1;
3038 struct table_elt
*best_elt
= elt
;
3039 rtx best_rtx
= *loc
;
3042 /* This is at worst case an O(n^2) algorithm, so limit our search
3043 to the first 32 elements on the list. This avoids trouble
3044 compiling code with very long basic blocks that can easily
3045 call simplify_gen_binary so many times that we run out of
3049 for (p
= elt
->first_same_value
, count
= 0;
3051 p
= p
->next_same_value
, count
++)
3053 && (GET_CODE (p
->exp
) == REG
3054 || exp_equiv_p (p
->exp
, p
->exp
, 1, 0)))
3056 rtx
new = simplify_gen_binary (GET_CODE (*loc
), Pmode
,
3059 new_cost
= address_cost (new, mode
);
3061 if (new_cost
< best_addr_cost
3062 || (new_cost
== best_addr_cost
3063 && (COST (new) + 1) >> 1 > best_rtx_cost
))
3066 best_addr_cost
= new_cost
;
3067 best_rtx_cost
= (COST (new) + 1) >> 1;
3075 if (validate_change (insn
, loc
,
3076 canon_reg (copy_rtx (best_rtx
),
3086 /* Given an operation (CODE, *PARG1, *PARG2), where code is a comparison
3087 operation (EQ, NE, GT, etc.), follow it back through the hash table and
3088 what values are being compared.
3090 *PARG1 and *PARG2 are updated to contain the rtx representing the values
3091 actually being compared. For example, if *PARG1 was (cc0) and *PARG2
3092 was (const_int 0), *PARG1 and *PARG2 will be set to the objects that were
3093 compared to produce cc0.
3095 The return value is the comparison operator and is either the code of
3096 A or the code corresponding to the inverse of the comparison. */
3098 static enum rtx_code
3099 find_comparison_args (code
, parg1
, parg2
, pmode1
, pmode2
)
3102 enum machine_mode
*pmode1
, *pmode2
;
3106 arg1
= *parg1
, arg2
= *parg2
;
3108 /* If ARG2 is const0_rtx, see what ARG1 is equivalent to. */
3110 while (arg2
== CONST0_RTX (GET_MODE (arg1
)))
3112 /* Set nonzero when we find something of interest. */
3114 int reverse_code
= 0;
3115 struct table_elt
*p
= 0;
3117 /* If arg1 is a COMPARE, extract the comparison arguments from it.
3118 On machines with CC0, this is the only case that can occur, since
3119 fold_rtx will return the COMPARE or item being compared with zero
3122 if (GET_CODE (arg1
) == COMPARE
&& arg2
== const0_rtx
)
3125 /* If ARG1 is a comparison operator and CODE is testing for
3126 STORE_FLAG_VALUE, get the inner arguments. */
3128 else if (GET_RTX_CLASS (GET_CODE (arg1
)) == '<')
3130 #ifdef FLOAT_STORE_FLAG_VALUE
3131 REAL_VALUE_TYPE fsfv
;
3135 || (GET_MODE_CLASS (GET_MODE (arg1
)) == MODE_INT
3136 && code
== LT
&& STORE_FLAG_VALUE
== -1)
3137 #ifdef FLOAT_STORE_FLAG_VALUE
3138 || (GET_MODE_CLASS (GET_MODE (arg1
)) == MODE_FLOAT
3139 && (fsfv
= FLOAT_STORE_FLAG_VALUE (GET_MODE (arg1
)),
3140 REAL_VALUE_NEGATIVE (fsfv
)))
3145 || (GET_MODE_CLASS (GET_MODE (arg1
)) == MODE_INT
3146 && code
== GE
&& STORE_FLAG_VALUE
== -1)
3147 #ifdef FLOAT_STORE_FLAG_VALUE
3148 || (GET_MODE_CLASS (GET_MODE (arg1
)) == MODE_FLOAT
3149 && (fsfv
= FLOAT_STORE_FLAG_VALUE (GET_MODE (arg1
)),
3150 REAL_VALUE_NEGATIVE (fsfv
)))
3153 x
= arg1
, reverse_code
= 1;
3156 /* ??? We could also check for
3158 (ne (and (eq (...) (const_int 1))) (const_int 0))
3160 and related forms, but let's wait until we see them occurring. */
3163 /* Look up ARG1 in the hash table and see if it has an equivalence
3164 that lets us see what is being compared. */
3165 p
= lookup (arg1
, safe_hash (arg1
, GET_MODE (arg1
)) & HASH_MASK
,
3169 p
= p
->first_same_value
;
3171 /* If what we compare is already known to be constant, that is as
3173 We need to break the loop in this case, because otherwise we
3174 can have an infinite loop when looking at a reg that is known
3175 to be a constant which is the same as a comparison of a reg
3176 against zero which appears later in the insn stream, which in
3177 turn is constant and the same as the comparison of the first reg
3183 for (; p
; p
= p
->next_same_value
)
3185 enum machine_mode inner_mode
= GET_MODE (p
->exp
);
3186 #ifdef FLOAT_STORE_FLAG_VALUE
3187 REAL_VALUE_TYPE fsfv
;
3190 /* If the entry isn't valid, skip it. */
3191 if (! exp_equiv_p (p
->exp
, p
->exp
, 1, 0))
3194 if (GET_CODE (p
->exp
) == COMPARE
3195 /* Another possibility is that this machine has a compare insn
3196 that includes the comparison code. In that case, ARG1 would
3197 be equivalent to a comparison operation that would set ARG1 to
3198 either STORE_FLAG_VALUE or zero. If this is an NE operation,
3199 ORIG_CODE is the actual comparison being done; if it is an EQ,
3200 we must reverse ORIG_CODE. On machine with a negative value
3201 for STORE_FLAG_VALUE, also look at LT and GE operations. */
3204 && GET_MODE_CLASS (inner_mode
) == MODE_INT
3205 && (GET_MODE_BITSIZE (inner_mode
)
3206 <= HOST_BITS_PER_WIDE_INT
)
3207 && (STORE_FLAG_VALUE
3208 & ((HOST_WIDE_INT
) 1
3209 << (GET_MODE_BITSIZE (inner_mode
) - 1))))
3210 #ifdef FLOAT_STORE_FLAG_VALUE
3212 && GET_MODE_CLASS (inner_mode
) == MODE_FLOAT
3213 && (fsfv
= FLOAT_STORE_FLAG_VALUE (GET_MODE (arg1
)),
3214 REAL_VALUE_NEGATIVE (fsfv
)))
3217 && GET_RTX_CLASS (GET_CODE (p
->exp
)) == '<'))
3222 else if ((code
== EQ
3224 && GET_MODE_CLASS (inner_mode
) == MODE_INT
3225 && (GET_MODE_BITSIZE (inner_mode
)
3226 <= HOST_BITS_PER_WIDE_INT
)
3227 && (STORE_FLAG_VALUE
3228 & ((HOST_WIDE_INT
) 1
3229 << (GET_MODE_BITSIZE (inner_mode
) - 1))))
3230 #ifdef FLOAT_STORE_FLAG_VALUE
3232 && GET_MODE_CLASS (inner_mode
) == MODE_FLOAT
3233 && (fsfv
= FLOAT_STORE_FLAG_VALUE (GET_MODE (arg1
)),
3234 REAL_VALUE_NEGATIVE (fsfv
)))
3237 && GET_RTX_CLASS (GET_CODE (p
->exp
)) == '<')
3244 /* If this non-trapping address, e.g. fp + constant, the
3245 equivalent is a better operand since it may let us predict
3246 the value of the comparison. */
3247 else if (!rtx_addr_can_trap_p (p
->exp
))
3254 /* If we didn't find a useful equivalence for ARG1, we are done.
3255 Otherwise, set up for the next iteration. */
3259 /* If we need to reverse the comparison, make sure that that is
3260 possible -- we can't necessarily infer the value of GE from LT
3261 with floating-point operands. */
3264 enum rtx_code reversed
= reversed_comparison_code (x
, NULL_RTX
);
3265 if (reversed
== UNKNOWN
)
3270 else if (GET_RTX_CLASS (GET_CODE (x
)) == '<')
3271 code
= GET_CODE (x
);
3272 arg1
= XEXP (x
, 0), arg2
= XEXP (x
, 1);
3275 /* Return our results. Return the modes from before fold_rtx
3276 because fold_rtx might produce const_int, and then it's too late. */
3277 *pmode1
= GET_MODE (arg1
), *pmode2
= GET_MODE (arg2
);
3278 *parg1
= fold_rtx (arg1
, 0), *parg2
= fold_rtx (arg2
, 0);
3283 /* If X is a nontrivial arithmetic operation on an argument
3284 for which a constant value can be determined, return
3285 the result of operating on that value, as a constant.
3286 Otherwise, return X, possibly with one or more operands
3287 modified by recursive calls to this function.
3289 If X is a register whose contents are known, we do NOT
3290 return those contents here. equiv_constant is called to
3293 INSN is the insn that we may be modifying. If it is 0, make a copy
3294 of X before modifying it. */
3302 enum machine_mode mode
;
3309 /* Folded equivalents of first two operands of X. */
3313 /* Constant equivalents of first three operands of X;
3314 0 when no such equivalent is known. */
3319 /* The mode of the first operand of X. We need this for sign and zero
3321 enum machine_mode mode_arg0
;
3326 mode
= GET_MODE (x
);
3327 code
= GET_CODE (x
);
3337 /* No use simplifying an EXPR_LIST
3338 since they are used only for lists of args
3339 in a function call's REG_EQUAL note. */
3341 /* Changing anything inside an ADDRESSOF is incorrect; we don't
3342 want to (e.g.,) make (addressof (const_int 0)) just because
3343 the location is known to be zero. */
3349 return prev_insn_cc0
;
3353 /* If the next insn is a CODE_LABEL followed by a jump table,
3354 PC's value is a LABEL_REF pointing to that label. That
3355 lets us fold switch statements on the VAX. */
3358 if (insn
&& tablejump_p (insn
, &next
, NULL
))
3359 return gen_rtx_LABEL_REF (Pmode
, next
);
3364 /* See if we previously assigned a constant value to this SUBREG. */
3365 if ((new = lookup_as_function (x
, CONST_INT
)) != 0
3366 || (new = lookup_as_function (x
, CONST_DOUBLE
)) != 0)
3369 /* If this is a paradoxical SUBREG, we have no idea what value the
3370 extra bits would have. However, if the operand is equivalent
3371 to a SUBREG whose operand is the same as our mode, and all the
3372 modes are within a word, we can just use the inner operand
3373 because these SUBREGs just say how to treat the register.
3375 Similarly if we find an integer constant. */
3377 if (GET_MODE_SIZE (mode
) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x
))))
3379 enum machine_mode imode
= GET_MODE (SUBREG_REG (x
));
3380 struct table_elt
*elt
;
3382 if (GET_MODE_SIZE (mode
) <= UNITS_PER_WORD
3383 && GET_MODE_SIZE (imode
) <= UNITS_PER_WORD
3384 && (elt
= lookup (SUBREG_REG (x
), HASH (SUBREG_REG (x
), imode
),
3386 for (elt
= elt
->first_same_value
; elt
; elt
= elt
->next_same_value
)
3388 if (CONSTANT_P (elt
->exp
)
3389 && GET_MODE (elt
->exp
) == VOIDmode
)
3392 if (GET_CODE (elt
->exp
) == SUBREG
3393 && GET_MODE (SUBREG_REG (elt
->exp
)) == mode
3394 && exp_equiv_p (elt
->exp
, elt
->exp
, 1, 0))
3395 return copy_rtx (SUBREG_REG (elt
->exp
));
3401 /* Fold SUBREG_REG. If it changed, see if we can simplify the SUBREG.
3402 We might be able to if the SUBREG is extracting a single word in an
3403 integral mode or extracting the low part. */
3405 folded_arg0
= fold_rtx (SUBREG_REG (x
), insn
);
3406 const_arg0
= equiv_constant (folded_arg0
);
3408 folded_arg0
= const_arg0
;
3410 if (folded_arg0
!= SUBREG_REG (x
))
3412 new = simplify_subreg (mode
, folded_arg0
,
3413 GET_MODE (SUBREG_REG (x
)), SUBREG_BYTE (x
));
3418 /* If this is a narrowing SUBREG and our operand is a REG, see if
3419 we can find an equivalence for REG that is an arithmetic operation
3420 in a wider mode where both operands are paradoxical SUBREGs
3421 from objects of our result mode. In that case, we couldn't report
3422 an equivalent value for that operation, since we don't know what the
3423 extra bits will be. But we can find an equivalence for this SUBREG
3424 by folding that operation is the narrow mode. This allows us to
3425 fold arithmetic in narrow modes when the machine only supports
3426 word-sized arithmetic.
3428 Also look for a case where we have a SUBREG whose operand is the
3429 same as our result. If both modes are smaller than a word, we
3430 are simply interpreting a register in different modes and we
3431 can use the inner value. */
3433 if (GET_CODE (folded_arg0
) == REG
3434 && GET_MODE_SIZE (mode
) < GET_MODE_SIZE (GET_MODE (folded_arg0
))
3435 && subreg_lowpart_p (x
))
3437 struct table_elt
*elt
;
3439 /* We can use HASH here since we know that canon_hash won't be
3441 elt
= lookup (folded_arg0
,
3442 HASH (folded_arg0
, GET_MODE (folded_arg0
)),
3443 GET_MODE (folded_arg0
));
3446 elt
= elt
->first_same_value
;
3448 for (; elt
; elt
= elt
->next_same_value
)
3450 enum rtx_code eltcode
= GET_CODE (elt
->exp
);
3452 /* Just check for unary and binary operations. */
3453 if (GET_RTX_CLASS (GET_CODE (elt
->exp
)) == '1'
3454 && GET_CODE (elt
->exp
) != SIGN_EXTEND
3455 && GET_CODE (elt
->exp
) != ZERO_EXTEND
3456 && GET_CODE (XEXP (elt
->exp
, 0)) == SUBREG
3457 && GET_MODE (SUBREG_REG (XEXP (elt
->exp
, 0))) == mode
3458 && (GET_MODE_CLASS (mode
)
3459 == GET_MODE_CLASS (GET_MODE (XEXP (elt
->exp
, 0)))))
3461 rtx op0
= SUBREG_REG (XEXP (elt
->exp
, 0));
3463 if (GET_CODE (op0
) != REG
&& ! CONSTANT_P (op0
))
3464 op0
= fold_rtx (op0
, NULL_RTX
);
3466 op0
= equiv_constant (op0
);
3468 new = simplify_unary_operation (GET_CODE (elt
->exp
), mode
,
3471 else if ((GET_RTX_CLASS (GET_CODE (elt
->exp
)) == '2'
3472 || GET_RTX_CLASS (GET_CODE (elt
->exp
)) == 'c')
3473 && eltcode
!= DIV
&& eltcode
!= MOD
3474 && eltcode
!= UDIV
&& eltcode
!= UMOD
3475 && eltcode
!= ASHIFTRT
&& eltcode
!= LSHIFTRT
3476 && eltcode
!= ROTATE
&& eltcode
!= ROTATERT
3477 && ((GET_CODE (XEXP (elt
->exp
, 0)) == SUBREG
3478 && (GET_MODE (SUBREG_REG (XEXP (elt
->exp
, 0)))
3480 || CONSTANT_P (XEXP (elt
->exp
, 0)))
3481 && ((GET_CODE (XEXP (elt
->exp
, 1)) == SUBREG
3482 && (GET_MODE (SUBREG_REG (XEXP (elt
->exp
, 1)))
3484 || CONSTANT_P (XEXP (elt
->exp
, 1))))
3486 rtx op0
= gen_lowpart_common (mode
, XEXP (elt
->exp
, 0));
3487 rtx op1
= gen_lowpart_common (mode
, XEXP (elt
->exp
, 1));
3489 if (op0
&& GET_CODE (op0
) != REG
&& ! CONSTANT_P (op0
))
3490 op0
= fold_rtx (op0
, NULL_RTX
);
3493 op0
= equiv_constant (op0
);
3495 if (op1
&& GET_CODE (op1
) != REG
&& ! CONSTANT_P (op1
))
3496 op1
= fold_rtx (op1
, NULL_RTX
);
3499 op1
= equiv_constant (op1
);
3501 /* If we are looking for the low SImode part of
3502 (ashift:DI c (const_int 32)), it doesn't work
3503 to compute that in SImode, because a 32-bit shift
3504 in SImode is unpredictable. We know the value is 0. */
3506 && GET_CODE (elt
->exp
) == ASHIFT
3507 && GET_CODE (op1
) == CONST_INT
3508 && INTVAL (op1
) >= GET_MODE_BITSIZE (mode
))
3510 if (INTVAL (op1
) < GET_MODE_BITSIZE (GET_MODE (elt
->exp
)))
3512 /* If the count fits in the inner mode's width,
3513 but exceeds the outer mode's width,
3514 the value will get truncated to 0
3518 /* If the count exceeds even the inner mode's width,
3519 don't fold this expression. */
3522 else if (op0
&& op1
)
3523 new = simplify_binary_operation (GET_CODE (elt
->exp
), mode
,
3527 else if (GET_CODE (elt
->exp
) == SUBREG
3528 && GET_MODE (SUBREG_REG (elt
->exp
)) == mode
3529 && (GET_MODE_SIZE (GET_MODE (folded_arg0
))
3531 && exp_equiv_p (elt
->exp
, elt
->exp
, 1, 0))
3532 new = copy_rtx (SUBREG_REG (elt
->exp
));
3543 /* If we have (NOT Y), see if Y is known to be (NOT Z).
3544 If so, (NOT Y) simplifies to Z. Similarly for NEG. */
3545 new = lookup_as_function (XEXP (x
, 0), code
);
3547 return fold_rtx (copy_rtx (XEXP (new, 0)), insn
);
3551 /* If we are not actually processing an insn, don't try to find the
3552 best address. Not only don't we care, but we could modify the
3553 MEM in an invalid way since we have no insn to validate against. */
3555 find_best_addr (insn
, &XEXP (x
, 0), GET_MODE (x
));
3558 /* Even if we don't fold in the insn itself,
3559 we can safely do so here, in hopes of getting a constant. */
3560 rtx addr
= fold_rtx (XEXP (x
, 0), NULL_RTX
);
3562 HOST_WIDE_INT offset
= 0;
3564 if (GET_CODE (addr
) == REG
3565 && REGNO_QTY_VALID_P (REGNO (addr
)))
3567 int addr_q
= REG_QTY (REGNO (addr
));
3568 struct qty_table_elem
*addr_ent
= &qty_table
[addr_q
];
3570 if (GET_MODE (addr
) == addr_ent
->mode
3571 && addr_ent
->const_rtx
!= NULL_RTX
)
3572 addr
= addr_ent
->const_rtx
;
3575 /* If address is constant, split it into a base and integer offset. */
3576 if (GET_CODE (addr
) == SYMBOL_REF
|| GET_CODE (addr
) == LABEL_REF
)
3578 else if (GET_CODE (addr
) == CONST
&& GET_CODE (XEXP (addr
, 0)) == PLUS
3579 && GET_CODE (XEXP (XEXP (addr
, 0), 1)) == CONST_INT
)
3581 base
= XEXP (XEXP (addr
, 0), 0);
3582 offset
= INTVAL (XEXP (XEXP (addr
, 0), 1));
3584 else if (GET_CODE (addr
) == LO_SUM
3585 && GET_CODE (XEXP (addr
, 1)) == SYMBOL_REF
)
3586 base
= XEXP (addr
, 1);
3587 else if (GET_CODE (addr
) == ADDRESSOF
)
3588 return change_address (x
, VOIDmode
, addr
);
3590 /* If this is a constant pool reference, we can fold it into its
3591 constant to allow better value tracking. */
3592 if (base
&& GET_CODE (base
) == SYMBOL_REF
3593 && CONSTANT_POOL_ADDRESS_P (base
))
3595 rtx constant
= get_pool_constant (base
);
3596 enum machine_mode const_mode
= get_pool_mode (base
);
3599 if (CONSTANT_P (constant
) && GET_CODE (constant
) != CONST_INT
)
3600 constant_pool_entries_cost
= COST (constant
);
3602 /* If we are loading the full constant, we have an equivalence. */
3603 if (offset
== 0 && mode
== const_mode
)
3606 /* If this actually isn't a constant (weird!), we can't do
3607 anything. Otherwise, handle the two most common cases:
3608 extracting a word from a multi-word constant, and extracting
3609 the low-order bits. Other cases don't seem common enough to
3611 if (! CONSTANT_P (constant
))
3614 if (GET_MODE_CLASS (mode
) == MODE_INT
3615 && GET_MODE_SIZE (mode
) == UNITS_PER_WORD
3616 && offset
% UNITS_PER_WORD
== 0
3617 && (new = operand_subword (constant
,
3618 offset
/ UNITS_PER_WORD
,
3619 0, const_mode
)) != 0)
3622 if (((BYTES_BIG_ENDIAN
3623 && offset
== GET_MODE_SIZE (GET_MODE (constant
)) - 1)
3624 || (! BYTES_BIG_ENDIAN
&& offset
== 0))
3625 && (new = gen_lowpart_if_possible (mode
, constant
)) != 0)
3629 /* If this is a reference to a label at a known position in a jump
3630 table, we also know its value. */
3631 if (base
&& GET_CODE (base
) == LABEL_REF
)
3633 rtx label
= XEXP (base
, 0);
3634 rtx table_insn
= NEXT_INSN (label
);
3636 if (table_insn
&& GET_CODE (table_insn
) == JUMP_INSN
3637 && GET_CODE (PATTERN (table_insn
)) == ADDR_VEC
)
3639 rtx table
= PATTERN (table_insn
);
3642 && (offset
/ GET_MODE_SIZE (GET_MODE (table
))
3643 < XVECLEN (table
, 0)))
3644 return XVECEXP (table
, 0,
3645 offset
/ GET_MODE_SIZE (GET_MODE (table
)));
3647 if (table_insn
&& GET_CODE (table_insn
) == JUMP_INSN
3648 && GET_CODE (PATTERN (table_insn
)) == ADDR_DIFF_VEC
)
3650 rtx table
= PATTERN (table_insn
);
3653 && (offset
/ GET_MODE_SIZE (GET_MODE (table
))
3654 < XVECLEN (table
, 1)))
3656 offset
/= GET_MODE_SIZE (GET_MODE (table
));
3657 new = gen_rtx_MINUS (Pmode
, XVECEXP (table
, 1, offset
),
3660 if (GET_MODE (table
) != Pmode
)
3661 new = gen_rtx_TRUNCATE (GET_MODE (table
), new);
3663 /* Indicate this is a constant. This isn't a
3664 valid form of CONST, but it will only be used
3665 to fold the next insns and then discarded, so
3668 Note this expression must be explicitly discarded,
3669 by cse_insn, else it may end up in a REG_EQUAL note
3670 and "escape" to cause problems elsewhere. */
3671 return gen_rtx_CONST (GET_MODE (new), new);
3679 #ifdef NO_FUNCTION_CSE
3681 if (CONSTANT_P (XEXP (XEXP (x
, 0), 0)))
3687 for (i
= ASM_OPERANDS_INPUT_LENGTH (x
) - 1; i
>= 0; i
--)
3688 validate_change (insn
, &ASM_OPERANDS_INPUT (x
, i
),
3689 fold_rtx (ASM_OPERANDS_INPUT (x
, i
), insn
), 0);
3699 mode_arg0
= VOIDmode
;
3701 /* Try folding our operands.
3702 Then see which ones have constant values known. */
3704 fmt
= GET_RTX_FORMAT (code
);
3705 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
3708 rtx arg
= XEXP (x
, i
);
3709 rtx folded_arg
= arg
, const_arg
= 0;
3710 enum machine_mode mode_arg
= GET_MODE (arg
);
3711 rtx cheap_arg
, expensive_arg
;
3712 rtx replacements
[2];
3714 int old_cost
= COST_IN (XEXP (x
, i
), code
);
3716 /* Most arguments are cheap, so handle them specially. */
3717 switch (GET_CODE (arg
))
3720 /* This is the same as calling equiv_constant; it is duplicated
3722 if (REGNO_QTY_VALID_P (REGNO (arg
)))
3724 int arg_q
= REG_QTY (REGNO (arg
));
3725 struct qty_table_elem
*arg_ent
= &qty_table
[arg_q
];
3727 if (arg_ent
->const_rtx
!= NULL_RTX
3728 && GET_CODE (arg_ent
->const_rtx
) != REG
3729 && GET_CODE (arg_ent
->const_rtx
) != PLUS
)
3731 = gen_lowpart_if_possible (GET_MODE (arg
),
3732 arg_ent
->const_rtx
);
3747 folded_arg
= prev_insn_cc0
;
3748 mode_arg
= prev_insn_cc0_mode
;
3749 const_arg
= equiv_constant (folded_arg
);
3754 folded_arg
= fold_rtx (arg
, insn
);
3755 const_arg
= equiv_constant (folded_arg
);
3758 /* For the first three operands, see if the operand
3759 is constant or equivalent to a constant. */
3763 folded_arg0
= folded_arg
;
3764 const_arg0
= const_arg
;
3765 mode_arg0
= mode_arg
;
3768 folded_arg1
= folded_arg
;
3769 const_arg1
= const_arg
;
3772 const_arg2
= const_arg
;
3776 /* Pick the least expensive of the folded argument and an
3777 equivalent constant argument. */
3778 if (const_arg
== 0 || const_arg
== folded_arg
3779 || COST_IN (const_arg
, code
) > COST_IN (folded_arg
, code
))
3780 cheap_arg
= folded_arg
, expensive_arg
= const_arg
;
3782 cheap_arg
= const_arg
, expensive_arg
= folded_arg
;
3784 /* Try to replace the operand with the cheapest of the two
3785 possibilities. If it doesn't work and this is either of the first
3786 two operands of a commutative operation, try swapping them.
3787 If THAT fails, try the more expensive, provided it is cheaper
3788 than what is already there. */
3790 if (cheap_arg
== XEXP (x
, i
))
3793 if (insn
== 0 && ! copied
)
3799 /* Order the replacements from cheapest to most expensive. */
3800 replacements
[0] = cheap_arg
;
3801 replacements
[1] = expensive_arg
;
3803 for (j
= 0; j
< 2 && replacements
[j
]; j
++)
3805 int new_cost
= COST_IN (replacements
[j
], code
);
3807 /* Stop if what existed before was cheaper. Prefer constants
3808 in the case of a tie. */
3809 if (new_cost
> old_cost
3810 || (new_cost
== old_cost
&& CONSTANT_P (XEXP (x
, i
))))
3813 if (validate_change (insn
, &XEXP (x
, i
), replacements
[j
], 0))
3816 if (code
== NE
|| code
== EQ
|| GET_RTX_CLASS (code
) == 'c'
3817 || code
== LTGT
|| code
== UNEQ
|| code
== ORDERED
3818 || code
== UNORDERED
)
3820 validate_change (insn
, &XEXP (x
, i
), XEXP (x
, 1 - i
), 1);
3821 validate_change (insn
, &XEXP (x
, 1 - i
), replacements
[j
], 1);
3823 if (apply_change_group ())
3825 /* Swap them back to be invalid so that this loop can
3826 continue and flag them to be swapped back later. */
3829 tem
= XEXP (x
, 0); XEXP (x
, 0) = XEXP (x
, 1);
3841 /* Don't try to fold inside of a vector of expressions.
3842 Doing nothing is harmless. */
3846 /* If a commutative operation, place a constant integer as the second
3847 operand unless the first operand is also a constant integer. Otherwise,
3848 place any constant second unless the first operand is also a constant. */
3850 if (code
== EQ
|| code
== NE
|| GET_RTX_CLASS (code
) == 'c'
3851 || code
== LTGT
|| code
== UNEQ
|| code
== ORDERED
3852 || code
== UNORDERED
)
3854 if (must_swap
|| (const_arg0
3856 || (GET_CODE (const_arg0
) == CONST_INT
3857 && GET_CODE (const_arg1
) != CONST_INT
))))
3859 rtx tem
= XEXP (x
, 0);
3861 if (insn
== 0 && ! copied
)
3867 validate_change (insn
, &XEXP (x
, 0), XEXP (x
, 1), 1);
3868 validate_change (insn
, &XEXP (x
, 1), tem
, 1);
3869 if (apply_change_group ())
3871 tem
= const_arg0
, const_arg0
= const_arg1
, const_arg1
= tem
;
3872 tem
= folded_arg0
, folded_arg0
= folded_arg1
, folded_arg1
= tem
;
3877 /* If X is an arithmetic operation, see if we can simplify it. */
3879 switch (GET_RTX_CLASS (code
))
3885 /* We can't simplify extension ops unless we know the
3887 if ((code
== ZERO_EXTEND
|| code
== SIGN_EXTEND
)
3888 && mode_arg0
== VOIDmode
)
3891 /* If we had a CONST, strip it off and put it back later if we
3893 if (const_arg0
!= 0 && GET_CODE (const_arg0
) == CONST
)
3894 is_const
= 1, const_arg0
= XEXP (const_arg0
, 0);
3896 new = simplify_unary_operation (code
, mode
,
3897 const_arg0
? const_arg0
: folded_arg0
,
3899 if (new != 0 && is_const
)
3900 new = gen_rtx_CONST (mode
, new);
3905 /* See what items are actually being compared and set FOLDED_ARG[01]
3906 to those values and CODE to the actual comparison code. If any are
3907 constant, set CONST_ARG0 and CONST_ARG1 appropriately. We needn't
3908 do anything if both operands are already known to be constant. */
3910 if (const_arg0
== 0 || const_arg1
== 0)
3912 struct table_elt
*p0
, *p1
;
3913 rtx true_rtx
= const_true_rtx
, false_rtx
= const0_rtx
;
3914 enum machine_mode mode_arg1
;
3916 #ifdef FLOAT_STORE_FLAG_VALUE
3917 if (GET_MODE_CLASS (mode
) == MODE_FLOAT
)
3919 true_rtx
= (CONST_DOUBLE_FROM_REAL_VALUE
3920 (FLOAT_STORE_FLAG_VALUE (mode
), mode
));
3921 false_rtx
= CONST0_RTX (mode
);
3925 code
= find_comparison_args (code
, &folded_arg0
, &folded_arg1
,
3926 &mode_arg0
, &mode_arg1
);
3927 const_arg0
= equiv_constant (folded_arg0
);
3928 const_arg1
= equiv_constant (folded_arg1
);
3930 /* If the mode is VOIDmode or a MODE_CC mode, we don't know
3931 what kinds of things are being compared, so we can't do
3932 anything with this comparison. */
3934 if (mode_arg0
== VOIDmode
|| GET_MODE_CLASS (mode_arg0
) == MODE_CC
)
3937 /* If we do not now have two constants being compared, see
3938 if we can nevertheless deduce some things about the
3940 if (const_arg0
== 0 || const_arg1
== 0)
3942 /* Some addresses are known to be nonzero. We don't know
3943 their sign, but equality comparisons are known. */
3944 if (const_arg1
== const0_rtx
3945 && nonzero_address_p (folded_arg0
))
3949 else if (code
== NE
)
3953 /* See if the two operands are the same. */
3955 if (folded_arg0
== folded_arg1
3956 || (GET_CODE (folded_arg0
) == REG
3957 && GET_CODE (folded_arg1
) == REG
3958 && (REG_QTY (REGNO (folded_arg0
))
3959 == REG_QTY (REGNO (folded_arg1
))))
3960 || ((p0
= lookup (folded_arg0
,
3961 (safe_hash (folded_arg0
, mode_arg0
)
3962 & HASH_MASK
), mode_arg0
))
3963 && (p1
= lookup (folded_arg1
,
3964 (safe_hash (folded_arg1
, mode_arg0
)
3965 & HASH_MASK
), mode_arg0
))
3966 && p0
->first_same_value
== p1
->first_same_value
))
3968 /* Sadly two equal NaNs are not equivalent. */
3969 if (!HONOR_NANS (mode_arg0
))
3970 return ((code
== EQ
|| code
== LE
|| code
== GE
3971 || code
== LEU
|| code
== GEU
|| code
== UNEQ
3972 || code
== UNLE
|| code
== UNGE
3974 ? true_rtx
: false_rtx
);
3975 /* Take care for the FP compares we can resolve. */
3976 if (code
== UNEQ
|| code
== UNLE
|| code
== UNGE
)
3978 if (code
== LTGT
|| code
== LT
|| code
== GT
)
3982 /* If FOLDED_ARG0 is a register, see if the comparison we are
3983 doing now is either the same as we did before or the reverse
3984 (we only check the reverse if not floating-point). */
3985 else if (GET_CODE (folded_arg0
) == REG
)
3987 int qty
= REG_QTY (REGNO (folded_arg0
));
3989 if (REGNO_QTY_VALID_P (REGNO (folded_arg0
)))
3991 struct qty_table_elem
*ent
= &qty_table
[qty
];
3993 if ((comparison_dominates_p (ent
->comparison_code
, code
)
3994 || (! FLOAT_MODE_P (mode_arg0
)
3995 && comparison_dominates_p (ent
->comparison_code
,
3996 reverse_condition (code
))))
3997 && (rtx_equal_p (ent
->comparison_const
, folded_arg1
)
3999 && rtx_equal_p (ent
->comparison_const
,
4001 || (GET_CODE (folded_arg1
) == REG
4002 && (REG_QTY (REGNO (folded_arg1
)) == ent
->comparison_qty
))))
4003 return (comparison_dominates_p (ent
->comparison_code
, code
)
4004 ? true_rtx
: false_rtx
);
4010 /* If we are comparing against zero, see if the first operand is
4011 equivalent to an IOR with a constant. If so, we may be able to
4012 determine the result of this comparison. */
4014 if (const_arg1
== const0_rtx
)
4016 rtx y
= lookup_as_function (folded_arg0
, IOR
);
4020 && (inner_const
= equiv_constant (XEXP (y
, 1))) != 0
4021 && GET_CODE (inner_const
) == CONST_INT
4022 && INTVAL (inner_const
) != 0)
4024 int sign_bitnum
= GET_MODE_BITSIZE (mode_arg0
) - 1;
4025 int has_sign
= (HOST_BITS_PER_WIDE_INT
>= sign_bitnum
4026 && (INTVAL (inner_const
)
4027 & ((HOST_WIDE_INT
) 1 << sign_bitnum
)));
4028 rtx true_rtx
= const_true_rtx
, false_rtx
= const0_rtx
;
4030 #ifdef FLOAT_STORE_FLAG_VALUE
4031 if (GET_MODE_CLASS (mode
) == MODE_FLOAT
)
4033 true_rtx
= (CONST_DOUBLE_FROM_REAL_VALUE
4034 (FLOAT_STORE_FLAG_VALUE (mode
), mode
));
4035 false_rtx
= CONST0_RTX (mode
);
4059 new = simplify_relational_operation (code
,
4060 (mode_arg0
!= VOIDmode
4062 : (GET_MODE (const_arg0
4066 ? GET_MODE (const_arg0
4069 : GET_MODE (const_arg1
4072 const_arg0
? const_arg0
: folded_arg0
,
4073 const_arg1
? const_arg1
: folded_arg1
);
4074 #ifdef FLOAT_STORE_FLAG_VALUE
4075 if (new != 0 && GET_MODE_CLASS (mode
) == MODE_FLOAT
)
4077 if (new == const0_rtx
)
4078 new = CONST0_RTX (mode
);
4080 new = (CONST_DOUBLE_FROM_REAL_VALUE
4081 (FLOAT_STORE_FLAG_VALUE (mode
), mode
));
4091 /* If the second operand is a LABEL_REF, see if the first is a MINUS
4092 with that LABEL_REF as its second operand. If so, the result is
4093 the first operand of that MINUS. This handles switches with an
4094 ADDR_DIFF_VEC table. */
4095 if (const_arg1
&& GET_CODE (const_arg1
) == LABEL_REF
)
4098 = GET_CODE (folded_arg0
) == MINUS
? folded_arg0
4099 : lookup_as_function (folded_arg0
, MINUS
);
4101 if (y
!= 0 && GET_CODE (XEXP (y
, 1)) == LABEL_REF
4102 && XEXP (XEXP (y
, 1), 0) == XEXP (const_arg1
, 0))
4105 /* Now try for a CONST of a MINUS like the above. */
4106 if ((y
= (GET_CODE (folded_arg0
) == CONST
? folded_arg0
4107 : lookup_as_function (folded_arg0
, CONST
))) != 0
4108 && GET_CODE (XEXP (y
, 0)) == MINUS
4109 && GET_CODE (XEXP (XEXP (y
, 0), 1)) == LABEL_REF
4110 && XEXP (XEXP (XEXP (y
, 0), 1), 0) == XEXP (const_arg1
, 0))
4111 return XEXP (XEXP (y
, 0), 0);
4114 /* Likewise if the operands are in the other order. */
4115 if (const_arg0
&& GET_CODE (const_arg0
) == LABEL_REF
)
4118 = GET_CODE (folded_arg1
) == MINUS
? folded_arg1
4119 : lookup_as_function (folded_arg1
, MINUS
);
4121 if (y
!= 0 && GET_CODE (XEXP (y
, 1)) == LABEL_REF
4122 && XEXP (XEXP (y
, 1), 0) == XEXP (const_arg0
, 0))
4125 /* Now try for a CONST of a MINUS like the above. */
4126 if ((y
= (GET_CODE (folded_arg1
) == CONST
? folded_arg1
4127 : lookup_as_function (folded_arg1
, CONST
))) != 0
4128 && GET_CODE (XEXP (y
, 0)) == MINUS
4129 && GET_CODE (XEXP (XEXP (y
, 0), 1)) == LABEL_REF
4130 && XEXP (XEXP (XEXP (y
, 0), 1), 0) == XEXP (const_arg0
, 0))
4131 return XEXP (XEXP (y
, 0), 0);
4134 /* If second operand is a register equivalent to a negative
4135 CONST_INT, see if we can find a register equivalent to the
4136 positive constant. Make a MINUS if so. Don't do this for
4137 a non-negative constant since we might then alternate between
4138 choosing positive and negative constants. Having the positive
4139 constant previously-used is the more common case. Be sure
4140 the resulting constant is non-negative; if const_arg1 were
4141 the smallest negative number this would overflow: depending
4142 on the mode, this would either just be the same value (and
4143 hence not save anything) or be incorrect. */
4144 if (const_arg1
!= 0 && GET_CODE (const_arg1
) == CONST_INT
4145 && INTVAL (const_arg1
) < 0
4146 /* This used to test
4148 -INTVAL (const_arg1) >= 0
4150 But The Sun V5.0 compilers mis-compiled that test. So
4151 instead we test for the problematic value in a more direct
4152 manner and hope the Sun compilers get it correct. */
4153 && INTVAL (const_arg1
) !=
4154 ((HOST_WIDE_INT
) 1 << (HOST_BITS_PER_WIDE_INT
- 1))
4155 && GET_CODE (folded_arg1
) == REG
)
4157 rtx new_const
= GEN_INT (-INTVAL (const_arg1
));
4159 = lookup (new_const
, safe_hash (new_const
, mode
) & HASH_MASK
,
4163 for (p
= p
->first_same_value
; p
; p
= p
->next_same_value
)
4164 if (GET_CODE (p
->exp
) == REG
)
4165 return simplify_gen_binary (MINUS
, mode
, folded_arg0
,
4166 canon_reg (p
->exp
, NULL_RTX
));
4171 /* If we have (MINUS Y C), see if Y is known to be (PLUS Z C2).
4172 If so, produce (PLUS Z C2-C). */
4173 if (const_arg1
!= 0 && GET_CODE (const_arg1
) == CONST_INT
)
4175 rtx y
= lookup_as_function (XEXP (x
, 0), PLUS
);
4176 if (y
&& GET_CODE (XEXP (y
, 1)) == CONST_INT
)
4177 return fold_rtx (plus_constant (copy_rtx (y
),
4178 -INTVAL (const_arg1
)),
4185 case SMIN
: case SMAX
: case UMIN
: case UMAX
:
4186 case IOR
: case AND
: case XOR
:
4188 case ASHIFT
: case LSHIFTRT
: case ASHIFTRT
:
4189 /* If we have (<op> <reg> <const_int>) for an associative OP and REG
4190 is known to be of similar form, we may be able to replace the
4191 operation with a combined operation. This may eliminate the
4192 intermediate operation if every use is simplified in this way.
4193 Note that the similar optimization done by combine.c only works
4194 if the intermediate operation's result has only one reference. */
4196 if (GET_CODE (folded_arg0
) == REG
4197 && const_arg1
&& GET_CODE (const_arg1
) == CONST_INT
)
4200 = (code
== ASHIFT
|| code
== ASHIFTRT
|| code
== LSHIFTRT
);
4201 rtx y
= lookup_as_function (folded_arg0
, code
);
4203 enum rtx_code associate_code
;
4207 || 0 == (inner_const
4208 = equiv_constant (fold_rtx (XEXP (y
, 1), 0)))
4209 || GET_CODE (inner_const
) != CONST_INT
4210 /* If we have compiled a statement like
4211 "if (x == (x & mask1))", and now are looking at
4212 "x & mask2", we will have a case where the first operand
4213 of Y is the same as our first operand. Unless we detect
4214 this case, an infinite loop will result. */
4215 || XEXP (y
, 0) == folded_arg0
)
4218 /* Don't associate these operations if they are a PLUS with the
4219 same constant and it is a power of two. These might be doable
4220 with a pre- or post-increment. Similarly for two subtracts of
4221 identical powers of two with post decrement. */
4223 if (code
== PLUS
&& INTVAL (const_arg1
) == INTVAL (inner_const
)
4224 && ((HAVE_PRE_INCREMENT
4225 && exact_log2 (INTVAL (const_arg1
)) >= 0)
4226 || (HAVE_POST_INCREMENT
4227 && exact_log2 (INTVAL (const_arg1
)) >= 0)
4228 || (HAVE_PRE_DECREMENT
4229 && exact_log2 (- INTVAL (const_arg1
)) >= 0)
4230 || (HAVE_POST_DECREMENT
4231 && exact_log2 (- INTVAL (const_arg1
)) >= 0)))
4234 /* Compute the code used to compose the constants. For example,
4235 A-C1-C2 is A-(C1 + C2), so if CODE == MINUS, we want PLUS. */
4237 associate_code
= (is_shift
|| code
== MINUS
? PLUS
: code
);
4239 new_const
= simplify_binary_operation (associate_code
, mode
,
4240 const_arg1
, inner_const
);
4245 /* If we are associating shift operations, don't let this
4246 produce a shift of the size of the object or larger.
4247 This could occur when we follow a sign-extend by a right
4248 shift on a machine that does a sign-extend as a pair
4251 if (is_shift
&& GET_CODE (new_const
) == CONST_INT
4252 && INTVAL (new_const
) >= GET_MODE_BITSIZE (mode
))
4254 /* As an exception, we can turn an ASHIFTRT of this
4255 form into a shift of the number of bits - 1. */
4256 if (code
== ASHIFTRT
)
4257 new_const
= GEN_INT (GET_MODE_BITSIZE (mode
) - 1);
4262 y
= copy_rtx (XEXP (y
, 0));
4264 /* If Y contains our first operand (the most common way this
4265 can happen is if Y is a MEM), we would do into an infinite
4266 loop if we tried to fold it. So don't in that case. */
4268 if (! reg_mentioned_p (folded_arg0
, y
))
4269 y
= fold_rtx (y
, insn
);
4271 return simplify_gen_binary (code
, mode
, y
, new_const
);
4275 case DIV
: case UDIV
:
4276 /* ??? The associative optimization performed immediately above is
4277 also possible for DIV and UDIV using associate_code of MULT.
4278 However, we would need extra code to verify that the
4279 multiplication does not overflow, that is, there is no overflow
4280 in the calculation of new_const. */
4287 new = simplify_binary_operation (code
, mode
,
4288 const_arg0
? const_arg0
: folded_arg0
,
4289 const_arg1
? const_arg1
: folded_arg1
);
4293 /* (lo_sum (high X) X) is simply X. */
4294 if (code
== LO_SUM
&& const_arg0
!= 0
4295 && GET_CODE (const_arg0
) == HIGH
4296 && rtx_equal_p (XEXP (const_arg0
, 0), const_arg1
))
4302 new = simplify_ternary_operation (code
, mode
, mode_arg0
,
4303 const_arg0
? const_arg0
: folded_arg0
,
4304 const_arg1
? const_arg1
: folded_arg1
,
4305 const_arg2
? const_arg2
: XEXP (x
, 2));
4309 /* Eliminate CONSTANT_P_RTX if its constant. */
4310 if (code
== CONSTANT_P_RTX
)
4314 if (optimize
== 0 || !flag_gcse
)
4320 return new ? new : x
;
4323 /* Return a constant value currently equivalent to X.
4324 Return 0 if we don't know one. */
4330 if (GET_CODE (x
) == REG
4331 && REGNO_QTY_VALID_P (REGNO (x
)))
4333 int x_q
= REG_QTY (REGNO (x
));
4334 struct qty_table_elem
*x_ent
= &qty_table
[x_q
];
4336 if (x_ent
->const_rtx
)
4337 x
= gen_lowpart_if_possible (GET_MODE (x
), x_ent
->const_rtx
);
4340 if (x
== 0 || CONSTANT_P (x
))
4343 /* If X is a MEM, try to fold it outside the context of any insn to see if
4344 it might be equivalent to a constant. That handles the case where it
4345 is a constant-pool reference. Then try to look it up in the hash table
4346 in case it is something whose value we have seen before. */
4348 if (GET_CODE (x
) == MEM
)
4350 struct table_elt
*elt
;
4352 x
= fold_rtx (x
, NULL_RTX
);
4356 elt
= lookup (x
, safe_hash (x
, GET_MODE (x
)) & HASH_MASK
, GET_MODE (x
));
4360 for (elt
= elt
->first_same_value
; elt
; elt
= elt
->next_same_value
)
4361 if (elt
->is_const
&& CONSTANT_P (elt
->exp
))
4368 /* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point
4369 number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the
4370 least-significant part of X.
4371 MODE specifies how big a part of X to return.
4373 If the requested operation cannot be done, 0 is returned.
4375 This is similar to gen_lowpart in emit-rtl.c. */
4378 gen_lowpart_if_possible (mode
, x
)
4379 enum machine_mode mode
;
4382 rtx result
= gen_lowpart_common (mode
, x
);
4386 else if (GET_CODE (x
) == MEM
)
4388 /* This is the only other case we handle. */
4392 if (WORDS_BIG_ENDIAN
)
4393 offset
= (MAX (GET_MODE_SIZE (GET_MODE (x
)), UNITS_PER_WORD
)
4394 - MAX (GET_MODE_SIZE (mode
), UNITS_PER_WORD
));
4395 if (BYTES_BIG_ENDIAN
)
4396 /* Adjust the address so that the address-after-the-data is
4398 offset
-= (MIN (UNITS_PER_WORD
, GET_MODE_SIZE (mode
))
4399 - MIN (UNITS_PER_WORD
, GET_MODE_SIZE (GET_MODE (x
))));
4401 new = adjust_address_nv (x
, mode
, offset
);
4402 if (! memory_address_p (mode
, XEXP (new, 0)))
4411 /* Given INSN, a jump insn, TAKEN indicates if we are following the "taken"
4412 branch. It will be zero if not.
4414 In certain cases, this can cause us to add an equivalence. For example,
4415 if we are following the taken case of
4417 we can add the fact that `i' and '2' are now equivalent.
4419 In any case, we can record that this comparison was passed. If the same
4420 comparison is seen later, we will know its value. */
4423 record_jump_equiv (insn
, taken
)
4427 int cond_known_true
;
4430 enum machine_mode mode
, mode0
, mode1
;
4431 int reversed_nonequality
= 0;
4434 /* Ensure this is the right kind of insn. */
4435 if (! any_condjump_p (insn
))
4437 set
= pc_set (insn
);
4439 /* See if this jump condition is known true or false. */
4441 cond_known_true
= (XEXP (SET_SRC (set
), 2) == pc_rtx
);
4443 cond_known_true
= (XEXP (SET_SRC (set
), 1) == pc_rtx
);
4445 /* Get the type of comparison being done and the operands being compared.
4446 If we had to reverse a non-equality condition, record that fact so we
4447 know that it isn't valid for floating-point. */
4448 code
= GET_CODE (XEXP (SET_SRC (set
), 0));
4449 op0
= fold_rtx (XEXP (XEXP (SET_SRC (set
), 0), 0), insn
);
4450 op1
= fold_rtx (XEXP (XEXP (SET_SRC (set
), 0), 1), insn
);
4452 code
= find_comparison_args (code
, &op0
, &op1
, &mode0
, &mode1
);
4453 if (! cond_known_true
)
4455 code
= reversed_comparison_code_parts (code
, op0
, op1
, insn
);
4457 /* Don't remember if we can't find the inverse. */
4458 if (code
== UNKNOWN
)
4462 /* The mode is the mode of the non-constant. */
4464 if (mode1
!= VOIDmode
)
4467 record_jump_cond (code
, mode
, op0
, op1
, reversed_nonequality
);
4470 /* We know that comparison CODE applied to OP0 and OP1 in MODE is true.
4471 REVERSED_NONEQUALITY is nonzero if CODE had to be swapped.
4472 Make any useful entries we can with that information. Called from
4473 above function and called recursively. */
4476 record_jump_cond (code
, mode
, op0
, op1
, reversed_nonequality
)
4478 enum machine_mode mode
;
4480 int reversed_nonequality
;
4482 unsigned op0_hash
, op1_hash
;
4483 int op0_in_memory
, op1_in_memory
;
4484 struct table_elt
*op0_elt
, *op1_elt
;
4486 /* If OP0 and OP1 are known equal, and either is a paradoxical SUBREG,
4487 we know that they are also equal in the smaller mode (this is also
4488 true for all smaller modes whether or not there is a SUBREG, but
4489 is not worth testing for with no SUBREG). */
4491 /* Note that GET_MODE (op0) may not equal MODE. */
4492 if (code
== EQ
&& GET_CODE (op0
) == SUBREG
4493 && (GET_MODE_SIZE (GET_MODE (op0
))
4494 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0
)))))
4496 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (op0
));
4497 rtx tem
= gen_lowpart_if_possible (inner_mode
, op1
);
4499 record_jump_cond (code
, mode
, SUBREG_REG (op0
),
4500 tem
? tem
: gen_rtx_SUBREG (inner_mode
, op1
, 0),
4501 reversed_nonequality
);
4504 if (code
== EQ
&& GET_CODE (op1
) == SUBREG
4505 && (GET_MODE_SIZE (GET_MODE (op1
))
4506 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (op1
)))))
4508 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (op1
));
4509 rtx tem
= gen_lowpart_if_possible (inner_mode
, op0
);
4511 record_jump_cond (code
, mode
, SUBREG_REG (op1
),
4512 tem
? tem
: gen_rtx_SUBREG (inner_mode
, op0
, 0),
4513 reversed_nonequality
);
4516 /* Similarly, if this is an NE comparison, and either is a SUBREG
4517 making a smaller mode, we know the whole thing is also NE. */
4519 /* Note that GET_MODE (op0) may not equal MODE;
4520 if we test MODE instead, we can get an infinite recursion
4521 alternating between two modes each wider than MODE. */
4523 if (code
== NE
&& GET_CODE (op0
) == SUBREG
4524 && subreg_lowpart_p (op0
)
4525 && (GET_MODE_SIZE (GET_MODE (op0
))
4526 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (op0
)))))
4528 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (op0
));
4529 rtx tem
= gen_lowpart_if_possible (inner_mode
, op1
);
4531 record_jump_cond (code
, mode
, SUBREG_REG (op0
),
4532 tem
? tem
: gen_rtx_SUBREG (inner_mode
, op1
, 0),
4533 reversed_nonequality
);
4536 if (code
== NE
&& GET_CODE (op1
) == SUBREG
4537 && subreg_lowpart_p (op1
)
4538 && (GET_MODE_SIZE (GET_MODE (op1
))
4539 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (op1
)))))
4541 enum machine_mode inner_mode
= GET_MODE (SUBREG_REG (op1
));
4542 rtx tem
= gen_lowpart_if_possible (inner_mode
, op0
);
4544 record_jump_cond (code
, mode
, SUBREG_REG (op1
),
4545 tem
? tem
: gen_rtx_SUBREG (inner_mode
, op0
, 0),
4546 reversed_nonequality
);
4549 /* Hash both operands. */
4552 hash_arg_in_memory
= 0;
4553 op0_hash
= HASH (op0
, mode
);
4554 op0_in_memory
= hash_arg_in_memory
;
4560 hash_arg_in_memory
= 0;
4561 op1_hash
= HASH (op1
, mode
);
4562 op1_in_memory
= hash_arg_in_memory
;
4567 /* Look up both operands. */
4568 op0_elt
= lookup (op0
, op0_hash
, mode
);
4569 op1_elt
= lookup (op1
, op1_hash
, mode
);
4571 /* If both operands are already equivalent or if they are not in the
4572 table but are identical, do nothing. */
4573 if ((op0_elt
!= 0 && op1_elt
!= 0
4574 && op0_elt
->first_same_value
== op1_elt
->first_same_value
)
4575 || op0
== op1
|| rtx_equal_p (op0
, op1
))
4578 /* If we aren't setting two things equal all we can do is save this
4579 comparison. Similarly if this is floating-point. In the latter
4580 case, OP1 might be zero and both -0.0 and 0.0 are equal to it.
4581 If we record the equality, we might inadvertently delete code
4582 whose intent was to change -0 to +0. */
4584 if (code
!= EQ
|| FLOAT_MODE_P (GET_MODE (op0
)))
4586 struct qty_table_elem
*ent
;
4589 /* If we reversed a floating-point comparison, if OP0 is not a
4590 register, or if OP1 is neither a register or constant, we can't
4593 if (GET_CODE (op1
) != REG
)
4594 op1
= equiv_constant (op1
);
4596 if ((reversed_nonequality
&& FLOAT_MODE_P (mode
))
4597 || GET_CODE (op0
) != REG
|| op1
== 0)
4600 /* Put OP0 in the hash table if it isn't already. This gives it a
4601 new quantity number. */
4604 if (insert_regs (op0
, NULL
, 0))
4606 rehash_using_reg (op0
);
4607 op0_hash
= HASH (op0
, mode
);
4609 /* If OP0 is contained in OP1, this changes its hash code
4610 as well. Faster to rehash than to check, except
4611 for the simple case of a constant. */
4612 if (! CONSTANT_P (op1
))
4613 op1_hash
= HASH (op1
,mode
);
4616 op0_elt
= insert (op0
, NULL
, op0_hash
, mode
);
4617 op0_elt
->in_memory
= op0_in_memory
;
4620 qty
= REG_QTY (REGNO (op0
));
4621 ent
= &qty_table
[qty
];
4623 ent
->comparison_code
= code
;
4624 if (GET_CODE (op1
) == REG
)
4626 /* Look it up again--in case op0 and op1 are the same. */
4627 op1_elt
= lookup (op1
, op1_hash
, mode
);
4629 /* Put OP1 in the hash table so it gets a new quantity number. */
4632 if (insert_regs (op1
, NULL
, 0))
4634 rehash_using_reg (op1
);
4635 op1_hash
= HASH (op1
, mode
);
4638 op1_elt
= insert (op1
, NULL
, op1_hash
, mode
);
4639 op1_elt
->in_memory
= op1_in_memory
;
4642 ent
->comparison_const
= NULL_RTX
;
4643 ent
->comparison_qty
= REG_QTY (REGNO (op1
));
4647 ent
->comparison_const
= op1
;
4648 ent
->comparison_qty
= -1;
4654 /* If either side is still missing an equivalence, make it now,
4655 then merge the equivalences. */
4659 if (insert_regs (op0
, NULL
, 0))
4661 rehash_using_reg (op0
);
4662 op0_hash
= HASH (op0
, mode
);
4665 op0_elt
= insert (op0
, NULL
, op0_hash
, mode
);
4666 op0_elt
->in_memory
= op0_in_memory
;
4671 if (insert_regs (op1
, NULL
, 0))
4673 rehash_using_reg (op1
);
4674 op1_hash
= HASH (op1
, mode
);
4677 op1_elt
= insert (op1
, NULL
, op1_hash
, mode
);
4678 op1_elt
->in_memory
= op1_in_memory
;
4681 merge_equiv_classes (op0_elt
, op1_elt
);
4682 last_jump_equiv_class
= op0_elt
;
4685 /* CSE processing for one instruction.
4686 First simplify sources and addresses of all assignments
4687 in the instruction, using previously-computed equivalents values.
4688 Then install the new sources and destinations in the table
4689 of available values.
4691 If LIBCALL_INSN is nonzero, don't record any equivalence made in
4692 the insn. It means that INSN is inside libcall block. In this
4693 case LIBCALL_INSN is the corresponding insn with REG_LIBCALL. */
4695 /* Data on one SET contained in the instruction. */
4699 /* The SET rtx itself. */
4701 /* The SET_SRC of the rtx (the original value, if it is changing). */
4703 /* The hash-table element for the SET_SRC of the SET. */
4704 struct table_elt
*src_elt
;
4705 /* Hash value for the SET_SRC. */
4707 /* Hash value for the SET_DEST. */
4709 /* The SET_DEST, with SUBREG, etc., stripped. */
4711 /* Nonzero if the SET_SRC is in memory. */
4713 /* Nonzero if the SET_SRC contains something
4714 whose value cannot be predicted and understood. */
4716 /* Original machine mode, in case it becomes a CONST_INT.
4717 The size of this field should match the size of the mode
4718 field of struct rtx_def (see rtl.h). */
4719 ENUM_BITFIELD(machine_mode
) mode
: 8;
4720 /* A constant equivalent for SET_SRC, if any. */
4722 /* Original SET_SRC value used for libcall notes. */
4724 /* Hash value of constant equivalent for SET_SRC. */
4725 unsigned src_const_hash
;
4726 /* Table entry for constant equivalent for SET_SRC, if any. */
4727 struct table_elt
*src_const_elt
;
4731 cse_insn (insn
, libcall_insn
)
4735 rtx x
= PATTERN (insn
);
4741 /* Records what this insn does to set CC0. */
4742 rtx this_insn_cc0
= 0;
4743 enum machine_mode this_insn_cc0_mode
= VOIDmode
;
4747 struct table_elt
*src_eqv_elt
= 0;
4748 int src_eqv_volatile
= 0;
4749 int src_eqv_in_memory
= 0;
4750 unsigned src_eqv_hash
= 0;
4752 struct set
*sets
= (struct set
*) 0;
4756 /* Find all the SETs and CLOBBERs in this instruction.
4757 Record all the SETs in the array `set' and count them.
4758 Also determine whether there is a CLOBBER that invalidates
4759 all memory references, or all references at varying addresses. */
4761 if (GET_CODE (insn
) == CALL_INSN
)
4763 for (tem
= CALL_INSN_FUNCTION_USAGE (insn
); tem
; tem
= XEXP (tem
, 1))
4765 if (GET_CODE (XEXP (tem
, 0)) == CLOBBER
)
4766 invalidate (SET_DEST (XEXP (tem
, 0)), VOIDmode
);
4767 XEXP (tem
, 0) = canon_reg (XEXP (tem
, 0), insn
);
4771 if (GET_CODE (x
) == SET
)
4773 sets
= (struct set
*) alloca (sizeof (struct set
));
4776 /* Ignore SETs that are unconditional jumps.
4777 They never need cse processing, so this does not hurt.
4778 The reason is not efficiency but rather
4779 so that we can test at the end for instructions
4780 that have been simplified to unconditional jumps
4781 and not be misled by unchanged instructions
4782 that were unconditional jumps to begin with. */
4783 if (SET_DEST (x
) == pc_rtx
4784 && GET_CODE (SET_SRC (x
)) == LABEL_REF
)
4787 /* Don't count call-insns, (set (reg 0) (call ...)), as a set.
4788 The hard function value register is used only once, to copy to
4789 someplace else, so it isn't worth cse'ing (and on 80386 is unsafe)!
4790 Ensure we invalidate the destination register. On the 80386 no
4791 other code would invalidate it since it is a fixed_reg.
4792 We need not check the return of apply_change_group; see canon_reg. */
4794 else if (GET_CODE (SET_SRC (x
)) == CALL
)
4796 canon_reg (SET_SRC (x
), insn
);
4797 apply_change_group ();
4798 fold_rtx (SET_SRC (x
), insn
);
4799 invalidate (SET_DEST (x
), VOIDmode
);
4804 else if (GET_CODE (x
) == PARALLEL
)
4806 int lim
= XVECLEN (x
, 0);
4808 sets
= (struct set
*) alloca (lim
* sizeof (struct set
));
4810 /* Find all regs explicitly clobbered in this insn,
4811 and ensure they are not replaced with any other regs
4812 elsewhere in this insn.
4813 When a reg that is clobbered is also used for input,
4814 we should presume that that is for a reason,
4815 and we should not substitute some other register
4816 which is not supposed to be clobbered.
4817 Therefore, this loop cannot be merged into the one below
4818 because a CALL may precede a CLOBBER and refer to the
4819 value clobbered. We must not let a canonicalization do
4820 anything in that case. */
4821 for (i
= 0; i
< lim
; i
++)
4823 rtx y
= XVECEXP (x
, 0, i
);
4824 if (GET_CODE (y
) == CLOBBER
)
4826 rtx clobbered
= XEXP (y
, 0);
4828 if (GET_CODE (clobbered
) == REG
4829 || GET_CODE (clobbered
) == SUBREG
)
4830 invalidate (clobbered
, VOIDmode
);
4831 else if (GET_CODE (clobbered
) == STRICT_LOW_PART
4832 || GET_CODE (clobbered
) == ZERO_EXTRACT
)
4833 invalidate (XEXP (clobbered
, 0), GET_MODE (clobbered
));
4837 for (i
= 0; i
< lim
; i
++)
4839 rtx y
= XVECEXP (x
, 0, i
);
4840 if (GET_CODE (y
) == SET
)
4842 /* As above, we ignore unconditional jumps and call-insns and
4843 ignore the result of apply_change_group. */
4844 if (GET_CODE (SET_SRC (y
)) == CALL
)
4846 canon_reg (SET_SRC (y
), insn
);
4847 apply_change_group ();
4848 fold_rtx (SET_SRC (y
), insn
);
4849 invalidate (SET_DEST (y
), VOIDmode
);
4851 else if (SET_DEST (y
) == pc_rtx
4852 && GET_CODE (SET_SRC (y
)) == LABEL_REF
)
4855 sets
[n_sets
++].rtl
= y
;
4857 else if (GET_CODE (y
) == CLOBBER
)
4859 /* If we clobber memory, canon the address.
4860 This does nothing when a register is clobbered
4861 because we have already invalidated the reg. */
4862 if (GET_CODE (XEXP (y
, 0)) == MEM
)
4863 canon_reg (XEXP (y
, 0), NULL_RTX
);
4865 else if (GET_CODE (y
) == USE
4866 && ! (GET_CODE (XEXP (y
, 0)) == REG
4867 && REGNO (XEXP (y
, 0)) < FIRST_PSEUDO_REGISTER
))
4868 canon_reg (y
, NULL_RTX
);
4869 else if (GET_CODE (y
) == CALL
)
4871 /* The result of apply_change_group can be ignored; see
4873 canon_reg (y
, insn
);
4874 apply_change_group ();
4879 else if (GET_CODE (x
) == CLOBBER
)
4881 if (GET_CODE (XEXP (x
, 0)) == MEM
)
4882 canon_reg (XEXP (x
, 0), NULL_RTX
);
4885 /* Canonicalize a USE of a pseudo register or memory location. */
4886 else if (GET_CODE (x
) == USE
4887 && ! (GET_CODE (XEXP (x
, 0)) == REG
4888 && REGNO (XEXP (x
, 0)) < FIRST_PSEUDO_REGISTER
))
4889 canon_reg (XEXP (x
, 0), NULL_RTX
);
4890 else if (GET_CODE (x
) == CALL
)
4892 /* The result of apply_change_group can be ignored; see canon_reg. */
4893 canon_reg (x
, insn
);
4894 apply_change_group ();
4898 /* Store the equivalent value in SRC_EQV, if different, or if the DEST
4899 is a STRICT_LOW_PART. The latter condition is necessary because SRC_EQV
4900 is handled specially for this case, and if it isn't set, then there will
4901 be no equivalence for the destination. */
4902 if (n_sets
== 1 && REG_NOTES (insn
) != 0
4903 && (tem
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
)) != 0
4904 && (! rtx_equal_p (XEXP (tem
, 0), SET_SRC (sets
[0].rtl
))
4905 || GET_CODE (SET_DEST (sets
[0].rtl
)) == STRICT_LOW_PART
))
4907 src_eqv
= fold_rtx (canon_reg (XEXP (tem
, 0), NULL_RTX
), insn
);
4908 XEXP (tem
, 0) = src_eqv
;
4911 /* Canonicalize sources and addresses of destinations.
4912 We do this in a separate pass to avoid problems when a MATCH_DUP is
4913 present in the insn pattern. In that case, we want to ensure that
4914 we don't break the duplicate nature of the pattern. So we will replace
4915 both operands at the same time. Otherwise, we would fail to find an
4916 equivalent substitution in the loop calling validate_change below.
4918 We used to suppress canonicalization of DEST if it appears in SRC,
4919 but we don't do this any more. */
4921 for (i
= 0; i
< n_sets
; i
++)
4923 rtx dest
= SET_DEST (sets
[i
].rtl
);
4924 rtx src
= SET_SRC (sets
[i
].rtl
);
4925 rtx
new = canon_reg (src
, insn
);
4928 sets
[i
].orig_src
= src
;
4929 if ((GET_CODE (new) == REG
&& GET_CODE (src
) == REG
4930 && ((REGNO (new) < FIRST_PSEUDO_REGISTER
)
4931 != (REGNO (src
) < FIRST_PSEUDO_REGISTER
)))
4932 || (insn_code
= recog_memoized (insn
)) < 0
4933 || insn_data
[insn_code
].n_dups
> 0)
4934 validate_change (insn
, &SET_SRC (sets
[i
].rtl
), new, 1);
4936 SET_SRC (sets
[i
].rtl
) = new;
4938 if (GET_CODE (dest
) == ZERO_EXTRACT
|| GET_CODE (dest
) == SIGN_EXTRACT
)
4940 validate_change (insn
, &XEXP (dest
, 1),
4941 canon_reg (XEXP (dest
, 1), insn
), 1);
4942 validate_change (insn
, &XEXP (dest
, 2),
4943 canon_reg (XEXP (dest
, 2), insn
), 1);
4946 while (GET_CODE (dest
) == SUBREG
|| GET_CODE (dest
) == STRICT_LOW_PART
4947 || GET_CODE (dest
) == ZERO_EXTRACT
4948 || GET_CODE (dest
) == SIGN_EXTRACT
)
4949 dest
= XEXP (dest
, 0);
4951 if (GET_CODE (dest
) == MEM
)
4952 canon_reg (dest
, insn
);
4955 /* Now that we have done all the replacements, we can apply the change
4956 group and see if they all work. Note that this will cause some
4957 canonicalizations that would have worked individually not to be applied
4958 because some other canonicalization didn't work, but this should not
4961 The result of apply_change_group can be ignored; see canon_reg. */
4963 apply_change_group ();
4965 /* Set sets[i].src_elt to the class each source belongs to.
4966 Detect assignments from or to volatile things
4967 and set set[i] to zero so they will be ignored
4968 in the rest of this function.
4970 Nothing in this loop changes the hash table or the register chains. */
4972 for (i
= 0; i
< n_sets
; i
++)
4976 struct table_elt
*elt
= 0, *p
;
4977 enum machine_mode mode
;
4980 rtx src_related
= 0;
4981 struct table_elt
*src_const_elt
= 0;
4982 int src_cost
= MAX_COST
;
4983 int src_eqv_cost
= MAX_COST
;
4984 int src_folded_cost
= MAX_COST
;
4985 int src_related_cost
= MAX_COST
;
4986 int src_elt_cost
= MAX_COST
;
4987 int src_regcost
= MAX_COST
;
4988 int src_eqv_regcost
= MAX_COST
;
4989 int src_folded_regcost
= MAX_COST
;
4990 int src_related_regcost
= MAX_COST
;
4991 int src_elt_regcost
= MAX_COST
;
4992 /* Set nonzero if we need to call force_const_mem on with the
4993 contents of src_folded before using it. */
4994 int src_folded_force_flag
= 0;
4996 dest
= SET_DEST (sets
[i
].rtl
);
4997 src
= SET_SRC (sets
[i
].rtl
);
4999 /* If SRC is a constant that has no machine mode,
5000 hash it with the destination's machine mode.
5001 This way we can keep different modes separate. */
5003 mode
= GET_MODE (src
) == VOIDmode
? GET_MODE (dest
) : GET_MODE (src
);
5004 sets
[i
].mode
= mode
;
5008 enum machine_mode eqvmode
= mode
;
5009 if (GET_CODE (dest
) == STRICT_LOW_PART
)
5010 eqvmode
= GET_MODE (SUBREG_REG (XEXP (dest
, 0)));
5012 hash_arg_in_memory
= 0;
5013 src_eqv_hash
= HASH (src_eqv
, eqvmode
);
5015 /* Find the equivalence class for the equivalent expression. */
5018 src_eqv_elt
= lookup (src_eqv
, src_eqv_hash
, eqvmode
);
5020 src_eqv_volatile
= do_not_record
;
5021 src_eqv_in_memory
= hash_arg_in_memory
;
5024 /* If this is a STRICT_LOW_PART assignment, src_eqv corresponds to the
5025 value of the INNER register, not the destination. So it is not
5026 a valid substitution for the source. But save it for later. */
5027 if (GET_CODE (dest
) == STRICT_LOW_PART
)
5030 src_eqv_here
= src_eqv
;
5032 /* Simplify and foldable subexpressions in SRC. Then get the fully-
5033 simplified result, which may not necessarily be valid. */
5034 src_folded
= fold_rtx (src
, insn
);
5037 /* ??? This caused bad code to be generated for the m68k port with -O2.
5038 Suppose src is (CONST_INT -1), and that after truncation src_folded
5039 is (CONST_INT 3). Suppose src_folded is then used for src_const.
5040 At the end we will add src and src_const to the same equivalence
5041 class. We now have 3 and -1 on the same equivalence class. This
5042 causes later instructions to be mis-optimized. */
5043 /* If storing a constant in a bitfield, pre-truncate the constant
5044 so we will be able to record it later. */
5045 if (GET_CODE (SET_DEST (sets
[i
].rtl
)) == ZERO_EXTRACT
5046 || GET_CODE (SET_DEST (sets
[i
].rtl
)) == SIGN_EXTRACT
)
5048 rtx width
= XEXP (SET_DEST (sets
[i
].rtl
), 1);
5050 if (GET_CODE (src
) == CONST_INT
5051 && GET_CODE (width
) == CONST_INT
5052 && INTVAL (width
) < HOST_BITS_PER_WIDE_INT
5053 && (INTVAL (src
) & ((HOST_WIDE_INT
) (-1) << INTVAL (width
))))
5055 = GEN_INT (INTVAL (src
) & (((HOST_WIDE_INT
) 1
5056 << INTVAL (width
)) - 1));
5060 /* Compute SRC's hash code, and also notice if it
5061 should not be recorded at all. In that case,
5062 prevent any further processing of this assignment. */
5064 hash_arg_in_memory
= 0;
5067 sets
[i
].src_hash
= HASH (src
, mode
);
5068 sets
[i
].src_volatile
= do_not_record
;
5069 sets
[i
].src_in_memory
= hash_arg_in_memory
;
5071 /* If SRC is a MEM, there is a REG_EQUIV note for SRC, and DEST is
5072 a pseudo, do not record SRC. Using SRC as a replacement for
5073 anything else will be incorrect in that situation. Note that
5074 this usually occurs only for stack slots, in which case all the
5075 RTL would be referring to SRC, so we don't lose any optimization
5076 opportunities by not having SRC in the hash table. */
5078 if (GET_CODE (src
) == MEM
5079 && find_reg_note (insn
, REG_EQUIV
, NULL_RTX
) != 0
5080 && GET_CODE (dest
) == REG
5081 && REGNO (dest
) >= FIRST_PSEUDO_REGISTER
)
5082 sets
[i
].src_volatile
= 1;
5085 /* It is no longer clear why we used to do this, but it doesn't
5086 appear to still be needed. So let's try without it since this
5087 code hurts cse'ing widened ops. */
5088 /* If source is a perverse subreg (such as QI treated as an SI),
5089 treat it as volatile. It may do the work of an SI in one context
5090 where the extra bits are not being used, but cannot replace an SI
5092 if (GET_CODE (src
) == SUBREG
5093 && (GET_MODE_SIZE (GET_MODE (src
))
5094 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (src
)))))
5095 sets
[i
].src_volatile
= 1;
5098 /* Locate all possible equivalent forms for SRC. Try to replace
5099 SRC in the insn with each cheaper equivalent.
5101 We have the following types of equivalents: SRC itself, a folded
5102 version, a value given in a REG_EQUAL note, or a value related
5105 Each of these equivalents may be part of an additional class
5106 of equivalents (if more than one is in the table, they must be in
5107 the same class; we check for this).
5109 If the source is volatile, we don't do any table lookups.
5111 We note any constant equivalent for possible later use in a
5114 if (!sets
[i
].src_volatile
)
5115 elt
= lookup (src
, sets
[i
].src_hash
, mode
);
5117 sets
[i
].src_elt
= elt
;
5119 if (elt
&& src_eqv_here
&& src_eqv_elt
)
5121 if (elt
->first_same_value
!= src_eqv_elt
->first_same_value
)
5123 /* The REG_EQUAL is indicating that two formerly distinct
5124 classes are now equivalent. So merge them. */
5125 merge_equiv_classes (elt
, src_eqv_elt
);
5126 src_eqv_hash
= HASH (src_eqv
, elt
->mode
);
5127 src_eqv_elt
= lookup (src_eqv
, src_eqv_hash
, elt
->mode
);
5133 else if (src_eqv_elt
)
5136 /* Try to find a constant somewhere and record it in `src_const'.
5137 Record its table element, if any, in `src_const_elt'. Look in
5138 any known equivalences first. (If the constant is not in the
5139 table, also set `sets[i].src_const_hash'). */
5141 for (p
= elt
->first_same_value
; p
; p
= p
->next_same_value
)
5145 src_const_elt
= elt
;
5150 && (CONSTANT_P (src_folded
)
5151 /* Consider (minus (label_ref L1) (label_ref L2)) as
5152 "constant" here so we will record it. This allows us
5153 to fold switch statements when an ADDR_DIFF_VEC is used. */
5154 || (GET_CODE (src_folded
) == MINUS
5155 && GET_CODE (XEXP (src_folded
, 0)) == LABEL_REF
5156 && GET_CODE (XEXP (src_folded
, 1)) == LABEL_REF
)))
5157 src_const
= src_folded
, src_const_elt
= elt
;
5158 else if (src_const
== 0 && src_eqv_here
&& CONSTANT_P (src_eqv_here
))
5159 src_const
= src_eqv_here
, src_const_elt
= src_eqv_elt
;
5161 /* If we don't know if the constant is in the table, get its
5162 hash code and look it up. */
5163 if (src_const
&& src_const_elt
== 0)
5165 sets
[i
].src_const_hash
= HASH (src_const
, mode
);
5166 src_const_elt
= lookup (src_const
, sets
[i
].src_const_hash
, mode
);
5169 sets
[i
].src_const
= src_const
;
5170 sets
[i
].src_const_elt
= src_const_elt
;
5172 /* If the constant and our source are both in the table, mark them as
5173 equivalent. Otherwise, if a constant is in the table but the source
5174 isn't, set ELT to it. */
5175 if (src_const_elt
&& elt
5176 && src_const_elt
->first_same_value
!= elt
->first_same_value
)
5177 merge_equiv_classes (elt
, src_const_elt
);
5178 else if (src_const_elt
&& elt
== 0)
5179 elt
= src_const_elt
;
5181 /* See if there is a register linearly related to a constant
5182 equivalent of SRC. */
5184 && (GET_CODE (src_const
) == CONST
5185 || (src_const_elt
&& src_const_elt
->related_value
!= 0)))
5187 src_related
= use_related_value (src_const
, src_const_elt
);
5190 struct table_elt
*src_related_elt
5191 = lookup (src_related
, HASH (src_related
, mode
), mode
);
5192 if (src_related_elt
&& elt
)
5194 if (elt
->first_same_value
5195 != src_related_elt
->first_same_value
)
5196 /* This can occur when we previously saw a CONST
5197 involving a SYMBOL_REF and then see the SYMBOL_REF
5198 twice. Merge the involved classes. */
5199 merge_equiv_classes (elt
, src_related_elt
);
5202 src_related_elt
= 0;
5204 else if (src_related_elt
&& elt
== 0)
5205 elt
= src_related_elt
;
5209 /* See if we have a CONST_INT that is already in a register in a
5212 if (src_const
&& src_related
== 0 && GET_CODE (src_const
) == CONST_INT
5213 && GET_MODE_CLASS (mode
) == MODE_INT
5214 && GET_MODE_BITSIZE (mode
) < BITS_PER_WORD
)
5216 enum machine_mode wider_mode
;
5218 for (wider_mode
= GET_MODE_WIDER_MODE (mode
);
5219 GET_MODE_BITSIZE (wider_mode
) <= BITS_PER_WORD
5220 && src_related
== 0;
5221 wider_mode
= GET_MODE_WIDER_MODE (wider_mode
))
5223 struct table_elt
*const_elt
5224 = lookup (src_const
, HASH (src_const
, wider_mode
), wider_mode
);
5229 for (const_elt
= const_elt
->first_same_value
;
5230 const_elt
; const_elt
= const_elt
->next_same_value
)
5231 if (GET_CODE (const_elt
->exp
) == REG
)
5233 src_related
= gen_lowpart_if_possible (mode
,
5240 /* Another possibility is that we have an AND with a constant in
5241 a mode narrower than a word. If so, it might have been generated
5242 as part of an "if" which would narrow the AND. If we already
5243 have done the AND in a wider mode, we can use a SUBREG of that
5246 if (flag_expensive_optimizations
&& ! src_related
5247 && GET_CODE (src
) == AND
&& GET_CODE (XEXP (src
, 1)) == CONST_INT
5248 && GET_MODE_SIZE (mode
) < UNITS_PER_WORD
)
5250 enum machine_mode tmode
;
5251 rtx new_and
= gen_rtx_AND (VOIDmode
, NULL_RTX
, XEXP (src
, 1));
5253 for (tmode
= GET_MODE_WIDER_MODE (mode
);
5254 GET_MODE_SIZE (tmode
) <= UNITS_PER_WORD
;
5255 tmode
= GET_MODE_WIDER_MODE (tmode
))
5257 rtx inner
= gen_lowpart_if_possible (tmode
, XEXP (src
, 0));
5258 struct table_elt
*larger_elt
;
5262 PUT_MODE (new_and
, tmode
);
5263 XEXP (new_and
, 0) = inner
;
5264 larger_elt
= lookup (new_and
, HASH (new_and
, tmode
), tmode
);
5265 if (larger_elt
== 0)
5268 for (larger_elt
= larger_elt
->first_same_value
;
5269 larger_elt
; larger_elt
= larger_elt
->next_same_value
)
5270 if (GET_CODE (larger_elt
->exp
) == REG
)
5273 = gen_lowpart_if_possible (mode
, larger_elt
->exp
);
5283 #ifdef LOAD_EXTEND_OP
5284 /* See if a MEM has already been loaded with a widening operation;
5285 if it has, we can use a subreg of that. Many CISC machines
5286 also have such operations, but this is only likely to be
5287 beneficial these machines. */
5289 if (flag_expensive_optimizations
&& src_related
== 0
5290 && (GET_MODE_SIZE (mode
) < UNITS_PER_WORD
)
5291 && GET_MODE_CLASS (mode
) == MODE_INT
5292 && GET_CODE (src
) == MEM
&& ! do_not_record
5293 && LOAD_EXTEND_OP (mode
) != NIL
)
5295 enum machine_mode tmode
;
5297 /* Set what we are trying to extend and the operation it might
5298 have been extended with. */
5299 PUT_CODE (memory_extend_rtx
, LOAD_EXTEND_OP (mode
));
5300 XEXP (memory_extend_rtx
, 0) = src
;
5302 for (tmode
= GET_MODE_WIDER_MODE (mode
);
5303 GET_MODE_SIZE (tmode
) <= UNITS_PER_WORD
;
5304 tmode
= GET_MODE_WIDER_MODE (tmode
))
5306 struct table_elt
*larger_elt
;
5308 PUT_MODE (memory_extend_rtx
, tmode
);
5309 larger_elt
= lookup (memory_extend_rtx
,
5310 HASH (memory_extend_rtx
, tmode
), tmode
);
5311 if (larger_elt
== 0)
5314 for (larger_elt
= larger_elt
->first_same_value
;
5315 larger_elt
; larger_elt
= larger_elt
->next_same_value
)
5316 if (GET_CODE (larger_elt
->exp
) == REG
)
5318 src_related
= gen_lowpart_if_possible (mode
,
5327 #endif /* LOAD_EXTEND_OP */
5329 if (src
== src_folded
)
5332 /* At this point, ELT, if nonzero, points to a class of expressions
5333 equivalent to the source of this SET and SRC, SRC_EQV, SRC_FOLDED,
5334 and SRC_RELATED, if nonzero, each contain additional equivalent
5335 expressions. Prune these latter expressions by deleting expressions
5336 already in the equivalence class.
5338 Check for an equivalent identical to the destination. If found,
5339 this is the preferred equivalent since it will likely lead to
5340 elimination of the insn. Indicate this by placing it in
5344 elt
= elt
->first_same_value
;
5345 for (p
= elt
; p
; p
= p
->next_same_value
)
5347 enum rtx_code code
= GET_CODE (p
->exp
);
5349 /* If the expression is not valid, ignore it. Then we do not
5350 have to check for validity below. In most cases, we can use
5351 `rtx_equal_p', since canonicalization has already been done. */
5352 if (code
!= REG
&& ! exp_equiv_p (p
->exp
, p
->exp
, 1, 0))
5355 /* Also skip paradoxical subregs, unless that's what we're
5358 && (GET_MODE_SIZE (GET_MODE (p
->exp
))
5359 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (p
->exp
))))
5361 && GET_CODE (src
) == SUBREG
5362 && GET_MODE (src
) == GET_MODE (p
->exp
)
5363 && (GET_MODE_SIZE (GET_MODE (SUBREG_REG (src
)))
5364 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (p
->exp
))))))
5367 if (src
&& GET_CODE (src
) == code
&& rtx_equal_p (src
, p
->exp
))
5369 else if (src_folded
&& GET_CODE (src_folded
) == code
5370 && rtx_equal_p (src_folded
, p
->exp
))
5372 else if (src_eqv_here
&& GET_CODE (src_eqv_here
) == code
5373 && rtx_equal_p (src_eqv_here
, p
->exp
))
5375 else if (src_related
&& GET_CODE (src_related
) == code
5376 && rtx_equal_p (src_related
, p
->exp
))
5379 /* This is the same as the destination of the insns, we want
5380 to prefer it. Copy it to src_related. The code below will
5381 then give it a negative cost. */
5382 if (GET_CODE (dest
) == code
&& rtx_equal_p (p
->exp
, dest
))
5386 /* Find the cheapest valid equivalent, trying all the available
5387 possibilities. Prefer items not in the hash table to ones
5388 that are when they are equal cost. Note that we can never
5389 worsen an insn as the current contents will also succeed.
5390 If we find an equivalent identical to the destination, use it as best,
5391 since this insn will probably be eliminated in that case. */
5394 if (rtx_equal_p (src
, dest
))
5395 src_cost
= src_regcost
= -1;
5398 src_cost
= COST (src
);
5399 src_regcost
= approx_reg_cost (src
);
5405 if (rtx_equal_p (src_eqv_here
, dest
))
5406 src_eqv_cost
= src_eqv_regcost
= -1;
5409 src_eqv_cost
= COST (src_eqv_here
);
5410 src_eqv_regcost
= approx_reg_cost (src_eqv_here
);
5416 if (rtx_equal_p (src_folded
, dest
))
5417 src_folded_cost
= src_folded_regcost
= -1;
5420 src_folded_cost
= COST (src_folded
);
5421 src_folded_regcost
= approx_reg_cost (src_folded
);
5427 if (rtx_equal_p (src_related
, dest
))
5428 src_related_cost
= src_related_regcost
= -1;
5431 src_related_cost
= COST (src_related
);
5432 src_related_regcost
= approx_reg_cost (src_related
);
5436 /* If this was an indirect jump insn, a known label will really be
5437 cheaper even though it looks more expensive. */
5438 if (dest
== pc_rtx
&& src_const
&& GET_CODE (src_const
) == LABEL_REF
)
5439 src_folded
= src_const
, src_folded_cost
= src_folded_regcost
= -1;
5441 /* Terminate loop when replacement made. This must terminate since
5442 the current contents will be tested and will always be valid. */
5447 /* Skip invalid entries. */
5448 while (elt
&& GET_CODE (elt
->exp
) != REG
5449 && ! exp_equiv_p (elt
->exp
, elt
->exp
, 1, 0))
5450 elt
= elt
->next_same_value
;
5452 /* A paradoxical subreg would be bad here: it'll be the right
5453 size, but later may be adjusted so that the upper bits aren't
5454 what we want. So reject it. */
5456 && GET_CODE (elt
->exp
) == SUBREG
5457 && (GET_MODE_SIZE (GET_MODE (elt
->exp
))
5458 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (elt
->exp
))))
5459 /* It is okay, though, if the rtx we're trying to match
5460 will ignore any of the bits we can't predict. */
5462 && GET_CODE (src
) == SUBREG
5463 && GET_MODE (src
) == GET_MODE (elt
->exp
)
5464 && (GET_MODE_SIZE (GET_MODE (SUBREG_REG (src
)))
5465 < GET_MODE_SIZE (GET_MODE (SUBREG_REG (elt
->exp
))))))
5467 elt
= elt
->next_same_value
;
5473 src_elt_cost
= elt
->cost
;
5474 src_elt_regcost
= elt
->regcost
;
5477 /* Find cheapest and skip it for the next time. For items
5478 of equal cost, use this order:
5479 src_folded, src, src_eqv, src_related and hash table entry. */
5481 && preferrable (src_folded_cost
, src_folded_regcost
,
5482 src_cost
, src_regcost
) <= 0
5483 && preferrable (src_folded_cost
, src_folded_regcost
,
5484 src_eqv_cost
, src_eqv_regcost
) <= 0
5485 && preferrable (src_folded_cost
, src_folded_regcost
,
5486 src_related_cost
, src_related_regcost
) <= 0
5487 && preferrable (src_folded_cost
, src_folded_regcost
,
5488 src_elt_cost
, src_elt_regcost
) <= 0)
5490 trial
= src_folded
, src_folded_cost
= MAX_COST
;
5491 if (src_folded_force_flag
)
5492 trial
= force_const_mem (mode
, trial
);
5495 && preferrable (src_cost
, src_regcost
,
5496 src_eqv_cost
, src_eqv_regcost
) <= 0
5497 && preferrable (src_cost
, src_regcost
,
5498 src_related_cost
, src_related_regcost
) <= 0
5499 && preferrable (src_cost
, src_regcost
,
5500 src_elt_cost
, src_elt_regcost
) <= 0)
5501 trial
= src
, src_cost
= MAX_COST
;
5502 else if (src_eqv_here
5503 && preferrable (src_eqv_cost
, src_eqv_regcost
,
5504 src_related_cost
, src_related_regcost
) <= 0
5505 && preferrable (src_eqv_cost
, src_eqv_regcost
,
5506 src_elt_cost
, src_elt_regcost
) <= 0)
5507 trial
= copy_rtx (src_eqv_here
), src_eqv_cost
= MAX_COST
;
5508 else if (src_related
5509 && preferrable (src_related_cost
, src_related_regcost
,
5510 src_elt_cost
, src_elt_regcost
) <= 0)
5511 trial
= copy_rtx (src_related
), src_related_cost
= MAX_COST
;
5514 trial
= copy_rtx (elt
->exp
);
5515 elt
= elt
->next_same_value
;
5516 src_elt_cost
= MAX_COST
;
5519 /* We don't normally have an insn matching (set (pc) (pc)), so
5520 check for this separately here. We will delete such an
5523 For other cases such as a table jump or conditional jump
5524 where we know the ultimate target, go ahead and replace the
5525 operand. While that may not make a valid insn, we will
5526 reemit the jump below (and also insert any necessary
5528 if (n_sets
== 1 && dest
== pc_rtx
5530 || (GET_CODE (trial
) == LABEL_REF
5531 && ! condjump_p (insn
))))
5533 SET_SRC (sets
[i
].rtl
) = trial
;
5534 cse_jumps_altered
= 1;
5538 /* Look for a substitution that makes a valid insn. */
5539 else if (validate_change (insn
, &SET_SRC (sets
[i
].rtl
), trial
, 0))
5541 rtx
new = canon_reg (SET_SRC (sets
[i
].rtl
), insn
);
5543 /* If we just made a substitution inside a libcall, then we
5544 need to make the same substitution in any notes attached
5545 to the RETVAL insn. */
5547 && (GET_CODE (sets
[i
].orig_src
) == REG
5548 || GET_CODE (sets
[i
].orig_src
) == SUBREG
5549 || GET_CODE (sets
[i
].orig_src
) == MEM
))
5550 simplify_replace_rtx (REG_NOTES (libcall_insn
),
5551 sets
[i
].orig_src
, copy_rtx (new));
5553 /* The result of apply_change_group can be ignored; see
5556 validate_change (insn
, &SET_SRC (sets
[i
].rtl
), new, 1);
5557 apply_change_group ();
5561 /* If we previously found constant pool entries for
5562 constants and this is a constant, try making a
5563 pool entry. Put it in src_folded unless we already have done
5564 this since that is where it likely came from. */
5566 else if (constant_pool_entries_cost
5567 && CONSTANT_P (trial
)
5568 /* Reject cases that will abort in decode_rtx_const.
5569 On the alpha when simplifying a switch, we get
5570 (const (truncate (minus (label_ref) (label_ref)))). */
5571 && ! (GET_CODE (trial
) == CONST
5572 && GET_CODE (XEXP (trial
, 0)) == TRUNCATE
)
5573 /* Likewise on IA-64, except without the truncate. */
5574 && ! (GET_CODE (trial
) == CONST
5575 && GET_CODE (XEXP (trial
, 0)) == MINUS
5576 && GET_CODE (XEXP (XEXP (trial
, 0), 0)) == LABEL_REF
5577 && GET_CODE (XEXP (XEXP (trial
, 0), 1)) == LABEL_REF
)
5579 || (GET_CODE (src_folded
) != MEM
5580 && ! src_folded_force_flag
))
5581 && GET_MODE_CLASS (mode
) != MODE_CC
5582 && mode
!= VOIDmode
)
5584 src_folded_force_flag
= 1;
5586 src_folded_cost
= constant_pool_entries_cost
;
5590 src
= SET_SRC (sets
[i
].rtl
);
5592 /* In general, it is good to have a SET with SET_SRC == SET_DEST.
5593 However, there is an important exception: If both are registers
5594 that are not the head of their equivalence class, replace SET_SRC
5595 with the head of the class. If we do not do this, we will have
5596 both registers live over a portion of the basic block. This way,
5597 their lifetimes will likely abut instead of overlapping. */
5598 if (GET_CODE (dest
) == REG
5599 && REGNO_QTY_VALID_P (REGNO (dest
)))
5601 int dest_q
= REG_QTY (REGNO (dest
));
5602 struct qty_table_elem
*dest_ent
= &qty_table
[dest_q
];
5604 if (dest_ent
->mode
== GET_MODE (dest
)
5605 && dest_ent
->first_reg
!= REGNO (dest
)
5606 && GET_CODE (src
) == REG
&& REGNO (src
) == REGNO (dest
)
5607 /* Don't do this if the original insn had a hard reg as
5608 SET_SRC or SET_DEST. */
5609 && (GET_CODE (sets
[i
].src
) != REG
5610 || REGNO (sets
[i
].src
) >= FIRST_PSEUDO_REGISTER
)
5611 && (GET_CODE (dest
) != REG
|| REGNO (dest
) >= FIRST_PSEUDO_REGISTER
))
5612 /* We can't call canon_reg here because it won't do anything if
5613 SRC is a hard register. */
5615 int src_q
= REG_QTY (REGNO (src
));
5616 struct qty_table_elem
*src_ent
= &qty_table
[src_q
];
5617 int first
= src_ent
->first_reg
;
5619 = (first
>= FIRST_PSEUDO_REGISTER
5620 ? regno_reg_rtx
[first
] : gen_rtx_REG (GET_MODE (src
), first
));
5622 /* We must use validate-change even for this, because this
5623 might be a special no-op instruction, suitable only to
5625 if (validate_change (insn
, &SET_SRC (sets
[i
].rtl
), new_src
, 0))
5628 /* If we had a constant that is cheaper than what we are now
5629 setting SRC to, use that constant. We ignored it when we
5630 thought we could make this into a no-op. */
5631 if (src_const
&& COST (src_const
) < COST (src
)
5632 && validate_change (insn
, &SET_SRC (sets
[i
].rtl
),
5639 /* If we made a change, recompute SRC values. */
5640 if (src
!= sets
[i
].src
)
5644 hash_arg_in_memory
= 0;
5646 sets
[i
].src_hash
= HASH (src
, mode
);
5647 sets
[i
].src_volatile
= do_not_record
;
5648 sets
[i
].src_in_memory
= hash_arg_in_memory
;
5649 sets
[i
].src_elt
= lookup (src
, sets
[i
].src_hash
, mode
);
5652 /* If this is a single SET, we are setting a register, and we have an
5653 equivalent constant, we want to add a REG_NOTE. We don't want
5654 to write a REG_EQUAL note for a constant pseudo since verifying that
5655 that pseudo hasn't been eliminated is a pain. Such a note also
5656 won't help anything.
5658 Avoid a REG_EQUAL note for (CONST (MINUS (LABEL_REF) (LABEL_REF)))
5659 which can be created for a reference to a compile time computable
5660 entry in a jump table. */
5662 if (n_sets
== 1 && src_const
&& GET_CODE (dest
) == REG
5663 && GET_CODE (src_const
) != REG
5664 && ! (GET_CODE (src_const
) == CONST
5665 && GET_CODE (XEXP (src_const
, 0)) == MINUS
5666 && GET_CODE (XEXP (XEXP (src_const
, 0), 0)) == LABEL_REF
5667 && GET_CODE (XEXP (XEXP (src_const
, 0), 1)) == LABEL_REF
))
5669 /* We only want a REG_EQUAL note if src_const != src. */
5670 if (! rtx_equal_p (src
, src_const
))
5672 /* Make sure that the rtx is not shared. */
5673 src_const
= copy_rtx (src_const
);
5675 /* Record the actual constant value in a REG_EQUAL note,
5676 making a new one if one does not already exist. */
5677 set_unique_reg_note (insn
, REG_EQUAL
, src_const
);
5680 /* If storing a constant value in a register that
5681 previously held the constant value 0,
5682 record this fact with a REG_WAS_0 note on this insn.
5684 Note that the *register* is required to have previously held 0,
5685 not just any register in the quantity and we must point to the
5686 insn that set that register to zero.
5688 Rather than track each register individually, we just see if
5689 the last set for this quantity was for this register. */
5691 if (REGNO_QTY_VALID_P (REGNO (dest
)))
5693 int dest_q
= REG_QTY (REGNO (dest
));
5694 struct qty_table_elem
*dest_ent
= &qty_table
[dest_q
];
5696 if (dest_ent
->const_rtx
== const0_rtx
)
5698 /* See if we previously had a REG_WAS_0 note. */
5699 rtx note
= find_reg_note (insn
, REG_WAS_0
, NULL_RTX
);
5700 rtx const_insn
= dest_ent
->const_insn
;
5702 if ((tem
= single_set (const_insn
)) != 0
5703 && rtx_equal_p (SET_DEST (tem
), dest
))
5706 XEXP (note
, 0) = const_insn
;
5709 = gen_rtx_INSN_LIST (REG_WAS_0
, const_insn
,
5716 /* Now deal with the destination. */
5719 /* Look within any SIGN_EXTRACT or ZERO_EXTRACT
5720 to the MEM or REG within it. */
5721 while (GET_CODE (dest
) == SIGN_EXTRACT
5722 || GET_CODE (dest
) == ZERO_EXTRACT
5723 || GET_CODE (dest
) == SUBREG
5724 || GET_CODE (dest
) == STRICT_LOW_PART
)
5725 dest
= XEXP (dest
, 0);
5727 sets
[i
].inner_dest
= dest
;
5729 if (GET_CODE (dest
) == MEM
)
5731 #ifdef PUSH_ROUNDING
5732 /* Stack pushes invalidate the stack pointer. */
5733 rtx addr
= XEXP (dest
, 0);
5734 if (GET_RTX_CLASS (GET_CODE (addr
)) == 'a'
5735 && XEXP (addr
, 0) == stack_pointer_rtx
)
5736 invalidate (stack_pointer_rtx
, Pmode
);
5738 dest
= fold_rtx (dest
, insn
);
5741 /* Compute the hash code of the destination now,
5742 before the effects of this instruction are recorded,
5743 since the register values used in the address computation
5744 are those before this instruction. */
5745 sets
[i
].dest_hash
= HASH (dest
, mode
);
5747 /* Don't enter a bit-field in the hash table
5748 because the value in it after the store
5749 may not equal what was stored, due to truncation. */
5751 if (GET_CODE (SET_DEST (sets
[i
].rtl
)) == ZERO_EXTRACT
5752 || GET_CODE (SET_DEST (sets
[i
].rtl
)) == SIGN_EXTRACT
)
5754 rtx width
= XEXP (SET_DEST (sets
[i
].rtl
), 1);
5756 if (src_const
!= 0 && GET_CODE (src_const
) == CONST_INT
5757 && GET_CODE (width
) == CONST_INT
5758 && INTVAL (width
) < HOST_BITS_PER_WIDE_INT
5759 && ! (INTVAL (src_const
)
5760 & ((HOST_WIDE_INT
) (-1) << INTVAL (width
))))
5761 /* Exception: if the value is constant,
5762 and it won't be truncated, record it. */
5766 /* This is chosen so that the destination will be invalidated
5767 but no new value will be recorded.
5768 We must invalidate because sometimes constant
5769 values can be recorded for bitfields. */
5770 sets
[i
].src_elt
= 0;
5771 sets
[i
].src_volatile
= 1;
5777 /* If only one set in a JUMP_INSN and it is now a no-op, we can delete
5779 else if (n_sets
== 1 && dest
== pc_rtx
&& src
== pc_rtx
)
5781 /* One less use of the label this insn used to jump to. */
5783 cse_jumps_altered
= 1;
5784 /* No more processing for this set. */
5788 /* If this SET is now setting PC to a label, we know it used to
5789 be a conditional or computed branch. */
5790 else if (dest
== pc_rtx
&& GET_CODE (src
) == LABEL_REF
)
5792 /* Now emit a BARRIER after the unconditional jump. */
5793 if (NEXT_INSN (insn
) == 0
5794 || GET_CODE (NEXT_INSN (insn
)) != BARRIER
)
5795 emit_barrier_after (insn
);
5797 /* We reemit the jump in as many cases as possible just in
5798 case the form of an unconditional jump is significantly
5799 different than a computed jump or conditional jump.
5801 If this insn has multiple sets, then reemitting the
5802 jump is nontrivial. So instead we just force rerecognition
5803 and hope for the best. */
5806 rtx
new = emit_jump_insn_after (gen_jump (XEXP (src
, 0)), insn
);
5808 JUMP_LABEL (new) = XEXP (src
, 0);
5809 LABEL_NUSES (XEXP (src
, 0))++;
5813 /* Now emit a BARRIER after the unconditional jump. */
5814 if (NEXT_INSN (insn
) == 0
5815 || GET_CODE (NEXT_INSN (insn
)) != BARRIER
)
5816 emit_barrier_after (insn
);
5819 INSN_CODE (insn
) = -1;
5821 never_reached_warning (insn
, NULL
);
5823 /* Do not bother deleting any unreachable code,
5824 let jump/flow do that. */
5826 cse_jumps_altered
= 1;
5830 /* If destination is volatile, invalidate it and then do no further
5831 processing for this assignment. */
5833 else if (do_not_record
)
5835 if (GET_CODE (dest
) == REG
|| GET_CODE (dest
) == SUBREG
)
5836 invalidate (dest
, VOIDmode
);
5837 else if (GET_CODE (dest
) == MEM
)
5839 /* Outgoing arguments for a libcall don't
5840 affect any recorded expressions. */
5841 if (! libcall_insn
|| insn
== libcall_insn
)
5842 invalidate (dest
, VOIDmode
);
5844 else if (GET_CODE (dest
) == STRICT_LOW_PART
5845 || GET_CODE (dest
) == ZERO_EXTRACT
)
5846 invalidate (XEXP (dest
, 0), GET_MODE (dest
));
5850 if (sets
[i
].rtl
!= 0 && dest
!= SET_DEST (sets
[i
].rtl
))
5851 sets
[i
].dest_hash
= HASH (SET_DEST (sets
[i
].rtl
), mode
);
5854 /* If setting CC0, record what it was set to, or a constant, if it
5855 is equivalent to a constant. If it is being set to a floating-point
5856 value, make a COMPARE with the appropriate constant of 0. If we
5857 don't do this, later code can interpret this as a test against
5858 const0_rtx, which can cause problems if we try to put it into an
5859 insn as a floating-point operand. */
5860 if (dest
== cc0_rtx
)
5862 this_insn_cc0
= src_const
&& mode
!= VOIDmode
? src_const
: src
;
5863 this_insn_cc0_mode
= mode
;
5864 if (FLOAT_MODE_P (mode
))
5865 this_insn_cc0
= gen_rtx_COMPARE (VOIDmode
, this_insn_cc0
,
5871 /* Now enter all non-volatile source expressions in the hash table
5872 if they are not already present.
5873 Record their equivalence classes in src_elt.
5874 This way we can insert the corresponding destinations into
5875 the same classes even if the actual sources are no longer in them
5876 (having been invalidated). */
5878 if (src_eqv
&& src_eqv_elt
== 0 && sets
[0].rtl
!= 0 && ! src_eqv_volatile
5879 && ! rtx_equal_p (src_eqv
, SET_DEST (sets
[0].rtl
)))
5881 struct table_elt
*elt
;
5882 struct table_elt
*classp
= sets
[0].src_elt
;
5883 rtx dest
= SET_DEST (sets
[0].rtl
);
5884 enum machine_mode eqvmode
= GET_MODE (dest
);
5886 if (GET_CODE (dest
) == STRICT_LOW_PART
)
5888 eqvmode
= GET_MODE (SUBREG_REG (XEXP (dest
, 0)));
5891 if (insert_regs (src_eqv
, classp
, 0))
5893 rehash_using_reg (src_eqv
);
5894 src_eqv_hash
= HASH (src_eqv
, eqvmode
);
5896 elt
= insert (src_eqv
, classp
, src_eqv_hash
, eqvmode
);
5897 elt
->in_memory
= src_eqv_in_memory
;
5900 /* Check to see if src_eqv_elt is the same as a set source which
5901 does not yet have an elt, and if so set the elt of the set source
5903 for (i
= 0; i
< n_sets
; i
++)
5904 if (sets
[i
].rtl
&& sets
[i
].src_elt
== 0
5905 && rtx_equal_p (SET_SRC (sets
[i
].rtl
), src_eqv
))
5906 sets
[i
].src_elt
= src_eqv_elt
;
5909 for (i
= 0; i
< n_sets
; i
++)
5910 if (sets
[i
].rtl
&& ! sets
[i
].src_volatile
5911 && ! rtx_equal_p (SET_SRC (sets
[i
].rtl
), SET_DEST (sets
[i
].rtl
)))
5913 if (GET_CODE (SET_DEST (sets
[i
].rtl
)) == STRICT_LOW_PART
)
5915 /* REG_EQUAL in setting a STRICT_LOW_PART
5916 gives an equivalent for the entire destination register,
5917 not just for the subreg being stored in now.
5918 This is a more interesting equivalence, so we arrange later
5919 to treat the entire reg as the destination. */
5920 sets
[i
].src_elt
= src_eqv_elt
;
5921 sets
[i
].src_hash
= src_eqv_hash
;
5925 /* Insert source and constant equivalent into hash table, if not
5927 struct table_elt
*classp
= src_eqv_elt
;
5928 rtx src
= sets
[i
].src
;
5929 rtx dest
= SET_DEST (sets
[i
].rtl
);
5930 enum machine_mode mode
5931 = GET_MODE (src
) == VOIDmode
? GET_MODE (dest
) : GET_MODE (src
);
5933 if (sets
[i
].src_elt
== 0)
5935 /* Don't put a hard register source into the table if this is
5936 the last insn of a libcall. In this case, we only need
5937 to put src_eqv_elt in src_elt. */
5938 if (! find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
5940 struct table_elt
*elt
;
5942 /* Note that these insert_regs calls cannot remove
5943 any of the src_elt's, because they would have failed to
5944 match if not still valid. */
5945 if (insert_regs (src
, classp
, 0))
5947 rehash_using_reg (src
);
5948 sets
[i
].src_hash
= HASH (src
, mode
);
5950 elt
= insert (src
, classp
, sets
[i
].src_hash
, mode
);
5951 elt
->in_memory
= sets
[i
].src_in_memory
;
5952 sets
[i
].src_elt
= classp
= elt
;
5955 sets
[i
].src_elt
= classp
;
5957 if (sets
[i
].src_const
&& sets
[i
].src_const_elt
== 0
5958 && src
!= sets
[i
].src_const
5959 && ! rtx_equal_p (sets
[i
].src_const
, src
))
5960 sets
[i
].src_elt
= insert (sets
[i
].src_const
, classp
,
5961 sets
[i
].src_const_hash
, mode
);
5964 else if (sets
[i
].src_elt
== 0)
5965 /* If we did not insert the source into the hash table (e.g., it was
5966 volatile), note the equivalence class for the REG_EQUAL value, if any,
5967 so that the destination goes into that class. */
5968 sets
[i
].src_elt
= src_eqv_elt
;
5970 invalidate_from_clobbers (x
);
5972 /* Some registers are invalidated by subroutine calls. Memory is
5973 invalidated by non-constant calls. */
5975 if (GET_CODE (insn
) == CALL_INSN
)
5977 if (! CONST_OR_PURE_CALL_P (insn
))
5978 invalidate_memory ();
5979 invalidate_for_call ();
5982 /* Now invalidate everything set by this instruction.
5983 If a SUBREG or other funny destination is being set,
5984 sets[i].rtl is still nonzero, so here we invalidate the reg
5985 a part of which is being set. */
5987 for (i
= 0; i
< n_sets
; i
++)
5990 /* We can't use the inner dest, because the mode associated with
5991 a ZERO_EXTRACT is significant. */
5992 rtx dest
= SET_DEST (sets
[i
].rtl
);
5994 /* Needed for registers to remove the register from its
5995 previous quantity's chain.
5996 Needed for memory if this is a nonvarying address, unless
5997 we have just done an invalidate_memory that covers even those. */
5998 if (GET_CODE (dest
) == REG
|| GET_CODE (dest
) == SUBREG
)
5999 invalidate (dest
, VOIDmode
);
6000 else if (GET_CODE (dest
) == MEM
)
6002 /* Outgoing arguments for a libcall don't
6003 affect any recorded expressions. */
6004 if (! libcall_insn
|| insn
== libcall_insn
)
6005 invalidate (dest
, VOIDmode
);
6007 else if (GET_CODE (dest
) == STRICT_LOW_PART
6008 || GET_CODE (dest
) == ZERO_EXTRACT
)
6009 invalidate (XEXP (dest
, 0), GET_MODE (dest
));
6012 /* A volatile ASM invalidates everything. */
6013 if (GET_CODE (insn
) == INSN
6014 && GET_CODE (PATTERN (insn
)) == ASM_OPERANDS
6015 && MEM_VOLATILE_P (PATTERN (insn
)))
6016 flush_hash_table ();
6018 /* Make sure registers mentioned in destinations
6019 are safe for use in an expression to be inserted.
6020 This removes from the hash table
6021 any invalid entry that refers to one of these registers.
6023 We don't care about the return value from mention_regs because
6024 we are going to hash the SET_DEST values unconditionally. */
6026 for (i
= 0; i
< n_sets
; i
++)
6030 rtx x
= SET_DEST (sets
[i
].rtl
);
6032 if (GET_CODE (x
) != REG
)
6036 /* We used to rely on all references to a register becoming
6037 inaccessible when a register changes to a new quantity,
6038 since that changes the hash code. However, that is not
6039 safe, since after HASH_SIZE new quantities we get a
6040 hash 'collision' of a register with its own invalid
6041 entries. And since SUBREGs have been changed not to
6042 change their hash code with the hash code of the register,
6043 it wouldn't work any longer at all. So we have to check
6044 for any invalid references lying around now.
6045 This code is similar to the REG case in mention_regs,
6046 but it knows that reg_tick has been incremented, and
6047 it leaves reg_in_table as -1 . */
6048 unsigned int regno
= REGNO (x
);
6049 unsigned int endregno
6050 = regno
+ (regno
>= FIRST_PSEUDO_REGISTER
? 1
6051 : HARD_REGNO_NREGS (regno
, GET_MODE (x
)));
6054 for (i
= regno
; i
< endregno
; i
++)
6056 if (REG_IN_TABLE (i
) >= 0)
6058 remove_invalid_refs (i
);
6059 REG_IN_TABLE (i
) = -1;
6066 /* We may have just removed some of the src_elt's from the hash table.
6067 So replace each one with the current head of the same class. */
6069 for (i
= 0; i
< n_sets
; i
++)
6072 if (sets
[i
].src_elt
&& sets
[i
].src_elt
->first_same_value
== 0)
6073 /* If elt was removed, find current head of same class,
6074 or 0 if nothing remains of that class. */
6076 struct table_elt
*elt
= sets
[i
].src_elt
;
6078 while (elt
&& elt
->prev_same_value
)
6079 elt
= elt
->prev_same_value
;
6081 while (elt
&& elt
->first_same_value
== 0)
6082 elt
= elt
->next_same_value
;
6083 sets
[i
].src_elt
= elt
? elt
->first_same_value
: 0;
6087 /* Now insert the destinations into their equivalence classes. */
6089 for (i
= 0; i
< n_sets
; i
++)
6092 rtx dest
= SET_DEST (sets
[i
].rtl
);
6093 rtx inner_dest
= sets
[i
].inner_dest
;
6094 struct table_elt
*elt
;
6096 /* Don't record value if we are not supposed to risk allocating
6097 floating-point values in registers that might be wider than
6099 if ((flag_float_store
6100 && GET_CODE (dest
) == MEM
6101 && FLOAT_MODE_P (GET_MODE (dest
)))
6102 /* Don't record BLKmode values, because we don't know the
6103 size of it, and can't be sure that other BLKmode values
6104 have the same or smaller size. */
6105 || GET_MODE (dest
) == BLKmode
6106 /* Don't record values of destinations set inside a libcall block
6107 since we might delete the libcall. Things should have been set
6108 up so we won't want to reuse such a value, but we play it safe
6111 /* If we didn't put a REG_EQUAL value or a source into the hash
6112 table, there is no point is recording DEST. */
6113 || sets
[i
].src_elt
== 0
6114 /* If DEST is a paradoxical SUBREG and SRC is a ZERO_EXTEND
6115 or SIGN_EXTEND, don't record DEST since it can cause
6116 some tracking to be wrong.
6118 ??? Think about this more later. */
6119 || (GET_CODE (dest
) == SUBREG
6120 && (GET_MODE_SIZE (GET_MODE (dest
))
6121 > GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest
))))
6122 && (GET_CODE (sets
[i
].src
) == SIGN_EXTEND
6123 || GET_CODE (sets
[i
].src
) == ZERO_EXTEND
)))
6126 /* STRICT_LOW_PART isn't part of the value BEING set,
6127 and neither is the SUBREG inside it.
6128 Note that in this case SETS[I].SRC_ELT is really SRC_EQV_ELT. */
6129 if (GET_CODE (dest
) == STRICT_LOW_PART
)
6130 dest
= SUBREG_REG (XEXP (dest
, 0));
6132 if (GET_CODE (dest
) == REG
|| GET_CODE (dest
) == SUBREG
)
6133 /* Registers must also be inserted into chains for quantities. */
6134 if (insert_regs (dest
, sets
[i
].src_elt
, 1))
6136 /* If `insert_regs' changes something, the hash code must be
6138 rehash_using_reg (dest
);
6139 sets
[i
].dest_hash
= HASH (dest
, GET_MODE (dest
));
6142 if (GET_CODE (inner_dest
) == MEM
6143 && GET_CODE (XEXP (inner_dest
, 0)) == ADDRESSOF
)
6144 /* Given (SET (MEM (ADDRESSOF (X))) Y) we don't want to say
6145 that (MEM (ADDRESSOF (X))) is equivalent to Y.
6146 Consider the case in which the address of the MEM is
6147 passed to a function, which alters the MEM. Then, if we
6148 later use Y instead of the MEM we'll miss the update. */
6149 elt
= insert (dest
, 0, sets
[i
].dest_hash
, GET_MODE (dest
));
6151 elt
= insert (dest
, sets
[i
].src_elt
,
6152 sets
[i
].dest_hash
, GET_MODE (dest
));
6154 elt
->in_memory
= (GET_CODE (sets
[i
].inner_dest
) == MEM
6155 && (! RTX_UNCHANGING_P (sets
[i
].inner_dest
)
6156 || fixed_base_plus_p (XEXP (sets
[i
].inner_dest
,
6159 /* If we have (set (subreg:m1 (reg:m2 foo) 0) (bar:m1)), M1 is no
6160 narrower than M2, and both M1 and M2 are the same number of words,
6161 we are also doing (set (reg:m2 foo) (subreg:m2 (bar:m1) 0)) so
6162 make that equivalence as well.
6164 However, BAR may have equivalences for which gen_lowpart_if_possible
6165 will produce a simpler value than gen_lowpart_if_possible applied to
6166 BAR (e.g., if BAR was ZERO_EXTENDed from M2), so we will scan all
6167 BAR's equivalences. If we don't get a simplified form, make
6168 the SUBREG. It will not be used in an equivalence, but will
6169 cause two similar assignments to be detected.
6171 Note the loop below will find SUBREG_REG (DEST) since we have
6172 already entered SRC and DEST of the SET in the table. */
6174 if (GET_CODE (dest
) == SUBREG
6175 && (((GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest
))) - 1)
6177 == (GET_MODE_SIZE (GET_MODE (dest
)) - 1) / UNITS_PER_WORD
)
6178 && (GET_MODE_SIZE (GET_MODE (dest
))
6179 >= GET_MODE_SIZE (GET_MODE (SUBREG_REG (dest
))))
6180 && sets
[i
].src_elt
!= 0)
6182 enum machine_mode new_mode
= GET_MODE (SUBREG_REG (dest
));
6183 struct table_elt
*elt
, *classp
= 0;
6185 for (elt
= sets
[i
].src_elt
->first_same_value
; elt
;
6186 elt
= elt
->next_same_value
)
6190 struct table_elt
*src_elt
;
6193 /* Ignore invalid entries. */
6194 if (GET_CODE (elt
->exp
) != REG
6195 && ! exp_equiv_p (elt
->exp
, elt
->exp
, 1, 0))
6198 /* We may have already been playing subreg games. If the
6199 mode is already correct for the destination, use it. */
6200 if (GET_MODE (elt
->exp
) == new_mode
)
6204 /* Calculate big endian correction for the SUBREG_BYTE.
6205 We have already checked that M1 (GET_MODE (dest))
6206 is not narrower than M2 (new_mode). */
6207 if (BYTES_BIG_ENDIAN
)
6208 byte
= (GET_MODE_SIZE (GET_MODE (dest
))
6209 - GET_MODE_SIZE (new_mode
));
6211 new_src
= simplify_gen_subreg (new_mode
, elt
->exp
,
6212 GET_MODE (dest
), byte
);
6215 /* The call to simplify_gen_subreg fails if the value
6216 is VOIDmode, yet we can't do any simplification, e.g.
6217 for EXPR_LISTs denoting function call results.
6218 It is invalid to construct a SUBREG with a VOIDmode
6219 SUBREG_REG, hence a zero new_src means we can't do
6220 this substitution. */
6224 src_hash
= HASH (new_src
, new_mode
);
6225 src_elt
= lookup (new_src
, src_hash
, new_mode
);
6227 /* Put the new source in the hash table is if isn't
6231 if (insert_regs (new_src
, classp
, 0))
6233 rehash_using_reg (new_src
);
6234 src_hash
= HASH (new_src
, new_mode
);
6236 src_elt
= insert (new_src
, classp
, src_hash
, new_mode
);
6237 src_elt
->in_memory
= elt
->in_memory
;
6239 else if (classp
&& classp
!= src_elt
->first_same_value
)
6240 /* Show that two things that we've seen before are
6241 actually the same. */
6242 merge_equiv_classes (src_elt
, classp
);
6244 classp
= src_elt
->first_same_value
;
6245 /* Ignore invalid entries. */
6247 && GET_CODE (classp
->exp
) != REG
6248 && ! exp_equiv_p (classp
->exp
, classp
->exp
, 1, 0))
6249 classp
= classp
->next_same_value
;
6254 /* Special handling for (set REG0 REG1) where REG0 is the
6255 "cheapest", cheaper than REG1. After cse, REG1 will probably not
6256 be used in the sequel, so (if easily done) change this insn to
6257 (set REG1 REG0) and replace REG1 with REG0 in the previous insn
6258 that computed their value. Then REG1 will become a dead store
6259 and won't cloud the situation for later optimizations.
6261 Do not make this change if REG1 is a hard register, because it will
6262 then be used in the sequel and we may be changing a two-operand insn
6263 into a three-operand insn.
6265 Also do not do this if we are operating on a copy of INSN.
6267 Also don't do this if INSN ends a libcall; this would cause an unrelated
6268 register to be set in the middle of a libcall, and we then get bad code
6269 if the libcall is deleted. */
6271 if (n_sets
== 1 && sets
[0].rtl
&& GET_CODE (SET_DEST (sets
[0].rtl
)) == REG
6272 && NEXT_INSN (PREV_INSN (insn
)) == insn
6273 && GET_CODE (SET_SRC (sets
[0].rtl
)) == REG
6274 && REGNO (SET_SRC (sets
[0].rtl
)) >= FIRST_PSEUDO_REGISTER
6275 && REGNO_QTY_VALID_P (REGNO (SET_SRC (sets
[0].rtl
))))
6277 int src_q
= REG_QTY (REGNO (SET_SRC (sets
[0].rtl
)));
6278 struct qty_table_elem
*src_ent
= &qty_table
[src_q
];
6280 if ((src_ent
->first_reg
== REGNO (SET_DEST (sets
[0].rtl
)))
6281 && ! find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
6284 /* Scan for the previous nonnote insn, but stop at a basic
6288 prev
= PREV_INSN (prev
);
6290 while (prev
&& GET_CODE (prev
) == NOTE
6291 && NOTE_LINE_NUMBER (prev
) != NOTE_INSN_BASIC_BLOCK
);
6293 /* Do not swap the registers around if the previous instruction
6294 attaches a REG_EQUIV note to REG1.
6296 ??? It's not entirely clear whether we can transfer a REG_EQUIV
6297 from the pseudo that originally shadowed an incoming argument
6298 to another register. Some uses of REG_EQUIV might rely on it
6299 being attached to REG1 rather than REG2.
6301 This section previously turned the REG_EQUIV into a REG_EQUAL
6302 note. We cannot do that because REG_EQUIV may provide an
6303 uninitialized stack slot when REG_PARM_STACK_SPACE is used. */
6305 if (prev
!= 0 && GET_CODE (prev
) == INSN
6306 && GET_CODE (PATTERN (prev
)) == SET
6307 && SET_DEST (PATTERN (prev
)) == SET_SRC (sets
[0].rtl
)
6308 && ! find_reg_note (prev
, REG_EQUIV
, NULL_RTX
))
6310 rtx dest
= SET_DEST (sets
[0].rtl
);
6311 rtx src
= SET_SRC (sets
[0].rtl
);
6314 validate_change (prev
, &SET_DEST (PATTERN (prev
)), dest
, 1);
6315 validate_change (insn
, &SET_DEST (sets
[0].rtl
), src
, 1);
6316 validate_change (insn
, &SET_SRC (sets
[0].rtl
), dest
, 1);
6317 apply_change_group ();
6319 /* If there was a REG_WAS_0 note on PREV, remove it. Move
6320 any REG_WAS_0 note on INSN to PREV. */
6321 note
= find_reg_note (prev
, REG_WAS_0
, NULL_RTX
);
6323 remove_note (prev
, note
);
6325 note
= find_reg_note (insn
, REG_WAS_0
, NULL_RTX
);
6328 remove_note (insn
, note
);
6329 XEXP (note
, 1) = REG_NOTES (prev
);
6330 REG_NOTES (prev
) = note
;
6333 /* If INSN has a REG_EQUAL note, and this note mentions
6334 REG0, then we must delete it, because the value in
6335 REG0 has changed. If the note's value is REG1, we must
6336 also delete it because that is now this insn's dest. */
6337 note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
6339 && (reg_mentioned_p (dest
, XEXP (note
, 0))
6340 || rtx_equal_p (src
, XEXP (note
, 0))))
6341 remove_note (insn
, note
);
6346 /* If this is a conditional jump insn, record any known equivalences due to
6347 the condition being tested. */
6349 last_jump_equiv_class
= 0;
6350 if (GET_CODE (insn
) == JUMP_INSN
6351 && n_sets
== 1 && GET_CODE (x
) == SET
6352 && GET_CODE (SET_SRC (x
)) == IF_THEN_ELSE
)
6353 record_jump_equiv (insn
, 0);
6356 /* If the previous insn set CC0 and this insn no longer references CC0,
6357 delete the previous insn. Here we use the fact that nothing expects CC0
6358 to be valid over an insn, which is true until the final pass. */
6359 if (prev_insn
&& GET_CODE (prev_insn
) == INSN
6360 && (tem
= single_set (prev_insn
)) != 0
6361 && SET_DEST (tem
) == cc0_rtx
6362 && ! reg_mentioned_p (cc0_rtx
, x
))
6363 delete_insn (prev_insn
);
6365 prev_insn_cc0
= this_insn_cc0
;
6366 prev_insn_cc0_mode
= this_insn_cc0_mode
;
6371 /* Remove from the hash table all expressions that reference memory. */
6374 invalidate_memory ()
6377 struct table_elt
*p
, *next
;
6379 for (i
= 0; i
< HASH_SIZE
; i
++)
6380 for (p
= table
[i
]; p
; p
= next
)
6382 next
= p
->next_same_hash
;
6384 remove_from_table (p
, i
);
6388 /* If ADDR is an address that implicitly affects the stack pointer, return
6389 1 and update the register tables to show the effect. Else, return 0. */
6392 addr_affects_sp_p (addr
)
6395 if (GET_RTX_CLASS (GET_CODE (addr
)) == 'a'
6396 && GET_CODE (XEXP (addr
, 0)) == REG
6397 && REGNO (XEXP (addr
, 0)) == STACK_POINTER_REGNUM
)
6399 if (REG_TICK (STACK_POINTER_REGNUM
) >= 0)
6401 REG_TICK (STACK_POINTER_REGNUM
)++;
6402 /* Is it possible to use a subreg of SP? */
6403 SUBREG_TICKED (STACK_POINTER_REGNUM
) = -1;
6406 /* This should be *very* rare. */
6407 if (TEST_HARD_REG_BIT (hard_regs_in_table
, STACK_POINTER_REGNUM
))
6408 invalidate (stack_pointer_rtx
, VOIDmode
);
6416 /* Perform invalidation on the basis of everything about an insn
6417 except for invalidating the actual places that are SET in it.
6418 This includes the places CLOBBERed, and anything that might
6419 alias with something that is SET or CLOBBERed.
6421 X is the pattern of the insn. */
6424 invalidate_from_clobbers (x
)
6427 if (GET_CODE (x
) == CLOBBER
)
6429 rtx ref
= XEXP (x
, 0);
6432 if (GET_CODE (ref
) == REG
|| GET_CODE (ref
) == SUBREG
6433 || GET_CODE (ref
) == MEM
)
6434 invalidate (ref
, VOIDmode
);
6435 else if (GET_CODE (ref
) == STRICT_LOW_PART
6436 || GET_CODE (ref
) == ZERO_EXTRACT
)
6437 invalidate (XEXP (ref
, 0), GET_MODE (ref
));
6440 else if (GET_CODE (x
) == PARALLEL
)
6443 for (i
= XVECLEN (x
, 0) - 1; i
>= 0; i
--)
6445 rtx y
= XVECEXP (x
, 0, i
);
6446 if (GET_CODE (y
) == CLOBBER
)
6448 rtx ref
= XEXP (y
, 0);
6449 if (GET_CODE (ref
) == REG
|| GET_CODE (ref
) == SUBREG
6450 || GET_CODE (ref
) == MEM
)
6451 invalidate (ref
, VOIDmode
);
6452 else if (GET_CODE (ref
) == STRICT_LOW_PART
6453 || GET_CODE (ref
) == ZERO_EXTRACT
)
6454 invalidate (XEXP (ref
, 0), GET_MODE (ref
));
6460 /* Process X, part of the REG_NOTES of an insn. Look at any REG_EQUAL notes
6461 and replace any registers in them with either an equivalent constant
6462 or the canonical form of the register. If we are inside an address,
6463 only do this if the address remains valid.
6465 OBJECT is 0 except when within a MEM in which case it is the MEM.
6467 Return the replacement for X. */
6470 cse_process_notes (x
, object
)
6474 enum rtx_code code
= GET_CODE (x
);
6475 const char *fmt
= GET_RTX_FORMAT (code
);
6492 validate_change (x
, &XEXP (x
, 0),
6493 cse_process_notes (XEXP (x
, 0), x
), 0);
6498 if (REG_NOTE_KIND (x
) == REG_EQUAL
)
6499 XEXP (x
, 0) = cse_process_notes (XEXP (x
, 0), NULL_RTX
);
6501 XEXP (x
, 1) = cse_process_notes (XEXP (x
, 1), NULL_RTX
);
6508 rtx
new = cse_process_notes (XEXP (x
, 0), object
);
6509 /* We don't substitute VOIDmode constants into these rtx,
6510 since they would impede folding. */
6511 if (GET_MODE (new) != VOIDmode
)
6512 validate_change (object
, &XEXP (x
, 0), new, 0);
6517 i
= REG_QTY (REGNO (x
));
6519 /* Return a constant or a constant register. */
6520 if (REGNO_QTY_VALID_P (REGNO (x
)))
6522 struct qty_table_elem
*ent
= &qty_table
[i
];
6524 if (ent
->const_rtx
!= NULL_RTX
6525 && (CONSTANT_P (ent
->const_rtx
)
6526 || GET_CODE (ent
->const_rtx
) == REG
))
6528 rtx
new = gen_lowpart_if_possible (GET_MODE (x
), ent
->const_rtx
);
6534 /* Otherwise, canonicalize this register. */
6535 return canon_reg (x
, NULL_RTX
);
6541 for (i
= 0; i
< GET_RTX_LENGTH (code
); i
++)
6543 validate_change (object
, &XEXP (x
, i
),
6544 cse_process_notes (XEXP (x
, i
), object
), 0);
6549 /* Find common subexpressions between the end test of a loop and the beginning
6550 of the loop. LOOP_START is the CODE_LABEL at the start of a loop.
6552 Often we have a loop where an expression in the exit test is used
6553 in the body of the loop. For example "while (*p) *q++ = *p++;".
6554 Because of the way we duplicate the loop exit test in front of the loop,
6555 however, we don't detect that common subexpression. This will be caught
6556 when global cse is implemented, but this is a quite common case.
6558 This function handles the most common cases of these common expressions.
6559 It is called after we have processed the basic block ending with the
6560 NOTE_INSN_LOOP_END note that ends a loop and the previous JUMP_INSN
6561 jumps to a label used only once. */
6564 cse_around_loop (loop_start
)
6569 struct table_elt
*p
;
6571 /* If the jump at the end of the loop doesn't go to the start, we don't
6573 for (insn
= PREV_INSN (loop_start
);
6574 insn
&& (GET_CODE (insn
) == NOTE
&& NOTE_LINE_NUMBER (insn
) >= 0);
6575 insn
= PREV_INSN (insn
))
6579 || GET_CODE (insn
) != NOTE
6580 || NOTE_LINE_NUMBER (insn
) != NOTE_INSN_LOOP_BEG
)
6583 /* If the last insn of the loop (the end test) was an NE comparison,
6584 we will interpret it as an EQ comparison, since we fell through
6585 the loop. Any equivalences resulting from that comparison are
6586 therefore not valid and must be invalidated. */
6587 if (last_jump_equiv_class
)
6588 for (p
= last_jump_equiv_class
->first_same_value
; p
;
6589 p
= p
->next_same_value
)
6591 if (GET_CODE (p
->exp
) == MEM
|| GET_CODE (p
->exp
) == REG
6592 || (GET_CODE (p
->exp
) == SUBREG
6593 && GET_CODE (SUBREG_REG (p
->exp
)) == REG
))
6594 invalidate (p
->exp
, VOIDmode
);
6595 else if (GET_CODE (p
->exp
) == STRICT_LOW_PART
6596 || GET_CODE (p
->exp
) == ZERO_EXTRACT
)
6597 invalidate (XEXP (p
->exp
, 0), GET_MODE (p
->exp
));
6600 /* Process insns starting after LOOP_START until we hit a CALL_INSN or
6601 a CODE_LABEL (we could handle a CALL_INSN, but it isn't worth it).
6603 The only thing we do with SET_DEST is invalidate entries, so we
6604 can safely process each SET in order. It is slightly less efficient
6605 to do so, but we only want to handle the most common cases.
6607 The gen_move_insn call in cse_set_around_loop may create new pseudos.
6608 These pseudos won't have valid entries in any of the tables indexed
6609 by register number, such as reg_qty. We avoid out-of-range array
6610 accesses by not processing any instructions created after cse started. */
6612 for (insn
= NEXT_INSN (loop_start
);
6613 GET_CODE (insn
) != CALL_INSN
&& GET_CODE (insn
) != CODE_LABEL
6614 && INSN_UID (insn
) < max_insn_uid
6615 && ! (GET_CODE (insn
) == NOTE
6616 && NOTE_LINE_NUMBER (insn
) == NOTE_INSN_LOOP_END
);
6617 insn
= NEXT_INSN (insn
))
6620 && (GET_CODE (PATTERN (insn
)) == SET
6621 || GET_CODE (PATTERN (insn
)) == CLOBBER
))
6622 cse_set_around_loop (PATTERN (insn
), insn
, loop_start
);
6623 else if (INSN_P (insn
) && GET_CODE (PATTERN (insn
)) == PARALLEL
)
6624 for (i
= XVECLEN (PATTERN (insn
), 0) - 1; i
>= 0; i
--)
6625 if (GET_CODE (XVECEXP (PATTERN (insn
), 0, i
)) == SET
6626 || GET_CODE (XVECEXP (PATTERN (insn
), 0, i
)) == CLOBBER
)
6627 cse_set_around_loop (XVECEXP (PATTERN (insn
), 0, i
), insn
,
6632 /* Process one SET of an insn that was skipped. We ignore CLOBBERs
6633 since they are done elsewhere. This function is called via note_stores. */
6636 invalidate_skipped_set (dest
, set
, data
)
6639 void *data ATTRIBUTE_UNUSED
;
6641 enum rtx_code code
= GET_CODE (dest
);
6644 && ! addr_affects_sp_p (dest
) /* If this is not a stack push ... */
6645 /* There are times when an address can appear varying and be a PLUS
6646 during this scan when it would be a fixed address were we to know
6647 the proper equivalences. So invalidate all memory if there is
6648 a BLKmode or nonscalar memory reference or a reference to a
6649 variable address. */
6650 && (MEM_IN_STRUCT_P (dest
) || GET_MODE (dest
) == BLKmode
6651 || cse_rtx_varies_p (XEXP (dest
, 0), 0)))
6653 invalidate_memory ();
6657 if (GET_CODE (set
) == CLOBBER
6662 if (code
== STRICT_LOW_PART
|| code
== ZERO_EXTRACT
)
6663 invalidate (XEXP (dest
, 0), GET_MODE (dest
));
6664 else if (code
== REG
|| code
== SUBREG
|| code
== MEM
)
6665 invalidate (dest
, VOIDmode
);
6668 /* Invalidate all insns from START up to the end of the function or the
6669 next label. This called when we wish to CSE around a block that is
6670 conditionally executed. */
6673 invalidate_skipped_block (start
)
6678 for (insn
= start
; insn
&& GET_CODE (insn
) != CODE_LABEL
;
6679 insn
= NEXT_INSN (insn
))
6681 if (! INSN_P (insn
))
6684 if (GET_CODE (insn
) == CALL_INSN
)
6686 if (! CONST_OR_PURE_CALL_P (insn
))
6687 invalidate_memory ();
6688 invalidate_for_call ();
6691 invalidate_from_clobbers (PATTERN (insn
));
6692 note_stores (PATTERN (insn
), invalidate_skipped_set
, NULL
);
6696 /* If modifying X will modify the value in *DATA (which is really an
6697 `rtx *'), indicate that fact by setting the pointed to value to
6701 cse_check_loop_start (x
, set
, data
)
6703 rtx set ATTRIBUTE_UNUSED
;
6706 rtx
*cse_check_loop_start_value
= (rtx
*) data
;
6708 if (*cse_check_loop_start_value
== NULL_RTX
6709 || GET_CODE (x
) == CC0
|| GET_CODE (x
) == PC
)
6712 if ((GET_CODE (x
) == MEM
&& GET_CODE (*cse_check_loop_start_value
) == MEM
)
6713 || reg_overlap_mentioned_p (x
, *cse_check_loop_start_value
))
6714 *cse_check_loop_start_value
= NULL_RTX
;
6717 /* X is a SET or CLOBBER contained in INSN that was found near the start of
6718 a loop that starts with the label at LOOP_START.
6720 If X is a SET, we see if its SET_SRC is currently in our hash table.
6721 If so, we see if it has a value equal to some register used only in the
6722 loop exit code (as marked by jump.c).
6724 If those two conditions are true, we search backwards from the start of
6725 the loop to see if that same value was loaded into a register that still
6726 retains its value at the start of the loop.
6728 If so, we insert an insn after the load to copy the destination of that
6729 load into the equivalent register and (try to) replace our SET_SRC with that
6732 In any event, we invalidate whatever this SET or CLOBBER modifies. */
6735 cse_set_around_loop (x
, insn
, loop_start
)
6740 struct table_elt
*src_elt
;
6742 /* If this is a SET, see if we can replace SET_SRC, but ignore SETs that
6743 are setting PC or CC0 or whose SET_SRC is already a register. */
6744 if (GET_CODE (x
) == SET
6745 && GET_CODE (SET_DEST (x
)) != PC
&& GET_CODE (SET_DEST (x
)) != CC0
6746 && GET_CODE (SET_SRC (x
)) != REG
)
6748 src_elt
= lookup (SET_SRC (x
),
6749 HASH (SET_SRC (x
), GET_MODE (SET_DEST (x
))),
6750 GET_MODE (SET_DEST (x
)));
6753 for (src_elt
= src_elt
->first_same_value
; src_elt
;
6754 src_elt
= src_elt
->next_same_value
)
6755 if (GET_CODE (src_elt
->exp
) == REG
&& REG_LOOP_TEST_P (src_elt
->exp
)
6756 && COST (src_elt
->exp
) < COST (SET_SRC (x
)))
6760 /* Look for an insn in front of LOOP_START that sets
6761 something in the desired mode to SET_SRC (x) before we hit
6762 a label or CALL_INSN. */
6764 for (p
= prev_nonnote_insn (loop_start
);
6765 p
&& GET_CODE (p
) != CALL_INSN
6766 && GET_CODE (p
) != CODE_LABEL
;
6767 p
= prev_nonnote_insn (p
))
6768 if ((set
= single_set (p
)) != 0
6769 && GET_CODE (SET_DEST (set
)) == REG
6770 && GET_MODE (SET_DEST (set
)) == src_elt
->mode
6771 && rtx_equal_p (SET_SRC (set
), SET_SRC (x
)))
6773 /* We now have to ensure that nothing between P
6774 and LOOP_START modified anything referenced in
6775 SET_SRC (x). We know that nothing within the loop
6776 can modify it, or we would have invalidated it in
6779 rtx cse_check_loop_start_value
= SET_SRC (x
);
6780 for (q
= p
; q
!= loop_start
; q
= NEXT_INSN (q
))
6782 note_stores (PATTERN (q
),
6783 cse_check_loop_start
,
6784 &cse_check_loop_start_value
);
6786 /* If nothing was changed and we can replace our
6787 SET_SRC, add an insn after P to copy its destination
6788 to what we will be replacing SET_SRC with. */
6789 if (cse_check_loop_start_value
6791 && !can_throw_internal (insn
)
6792 && validate_change (insn
, &SET_SRC (x
),
6795 /* If this creates new pseudos, this is unsafe,
6796 because the regno of new pseudo is unsuitable
6797 to index into reg_qty when cse_insn processes
6798 the new insn. Therefore, if a new pseudo was
6799 created, discard this optimization. */
6800 int nregs
= max_reg_num ();
6802 = gen_move_insn (src_elt
->exp
, SET_DEST (set
));
6803 if (nregs
!= max_reg_num ())
6805 if (! validate_change (insn
, &SET_SRC (x
),
6810 emit_insn_after (move
, p
);
6817 /* Deal with the destination of X affecting the stack pointer. */
6818 addr_affects_sp_p (SET_DEST (x
));
6820 /* See comment on similar code in cse_insn for explanation of these
6822 if (GET_CODE (SET_DEST (x
)) == REG
|| GET_CODE (SET_DEST (x
)) == SUBREG
6823 || GET_CODE (SET_DEST (x
)) == MEM
)
6824 invalidate (SET_DEST (x
), VOIDmode
);
6825 else if (GET_CODE (SET_DEST (x
)) == STRICT_LOW_PART
6826 || GET_CODE (SET_DEST (x
)) == ZERO_EXTRACT
)
6827 invalidate (XEXP (SET_DEST (x
), 0), GET_MODE (SET_DEST (x
)));
6830 /* Find the end of INSN's basic block and return its range,
6831 the total number of SETs in all the insns of the block, the last insn of the
6832 block, and the branch path.
6834 The branch path indicates which branches should be followed. If a nonzero
6835 path size is specified, the block should be rescanned and a different set
6836 of branches will be taken. The branch path is only used if
6837 FLAG_CSE_FOLLOW_JUMPS or FLAG_CSE_SKIP_BLOCKS is nonzero.
6839 DATA is a pointer to a struct cse_basic_block_data, defined below, that is
6840 used to describe the block. It is filled in with the information about
6841 the current block. The incoming structure's branch path, if any, is used
6842 to construct the output branch path. */
6845 cse_end_of_basic_block (insn
, data
, follow_jumps
, after_loop
, skip_blocks
)
6847 struct cse_basic_block_data
*data
;
6854 int low_cuid
= INSN_CUID (insn
), high_cuid
= INSN_CUID (insn
);
6855 rtx next
= INSN_P (insn
) ? insn
: next_real_insn (insn
);
6856 int path_size
= data
->path_size
;
6860 /* Update the previous branch path, if any. If the last branch was
6861 previously TAKEN, mark it NOT_TAKEN. If it was previously NOT_TAKEN,
6862 shorten the path by one and look at the previous branch. We know that
6863 at least one branch must have been taken if PATH_SIZE is nonzero. */
6864 while (path_size
> 0)
6866 if (data
->path
[path_size
- 1].status
!= NOT_TAKEN
)
6868 data
->path
[path_size
- 1].status
= NOT_TAKEN
;
6875 /* If the first instruction is marked with QImode, that means we've
6876 already processed this block. Our caller will look at DATA->LAST
6877 to figure out where to go next. We want to return the next block
6878 in the instruction stream, not some branched-to block somewhere
6879 else. We accomplish this by pretending our called forbid us to
6880 follow jumps, or skip blocks. */
6881 if (GET_MODE (insn
) == QImode
)
6882 follow_jumps
= skip_blocks
= 0;
6884 /* Scan to end of this basic block. */
6885 while (p
&& GET_CODE (p
) != CODE_LABEL
)
6887 /* Don't cse out the end of a loop. This makes a difference
6888 only for the unusual loops that always execute at least once;
6889 all other loops have labels there so we will stop in any case.
6890 Cse'ing out the end of the loop is dangerous because it
6891 might cause an invariant expression inside the loop
6892 to be reused after the end of the loop. This would make it
6893 hard to move the expression out of the loop in loop.c,
6894 especially if it is one of several equivalent expressions
6895 and loop.c would like to eliminate it.
6897 If we are running after loop.c has finished, we can ignore
6898 the NOTE_INSN_LOOP_END. */
6900 if (! after_loop
&& GET_CODE (p
) == NOTE
6901 && NOTE_LINE_NUMBER (p
) == NOTE_INSN_LOOP_END
)
6904 /* Don't cse over a call to setjmp; on some machines (eg VAX)
6905 the regs restored by the longjmp come from
6906 a later time than the setjmp. */
6907 if (PREV_INSN (p
) && GET_CODE (PREV_INSN (p
)) == CALL_INSN
6908 && find_reg_note (PREV_INSN (p
), REG_SETJMP
, NULL
))
6911 /* A PARALLEL can have lots of SETs in it,
6912 especially if it is really an ASM_OPERANDS. */
6913 if (INSN_P (p
) && GET_CODE (PATTERN (p
)) == PARALLEL
)
6914 nsets
+= XVECLEN (PATTERN (p
), 0);
6915 else if (GET_CODE (p
) != NOTE
)
6918 /* Ignore insns made by CSE; they cannot affect the boundaries of
6921 if (INSN_UID (p
) <= max_uid
&& INSN_CUID (p
) > high_cuid
)
6922 high_cuid
= INSN_CUID (p
);
6923 if (INSN_UID (p
) <= max_uid
&& INSN_CUID (p
) < low_cuid
)
6924 low_cuid
= INSN_CUID (p
);
6926 /* See if this insn is in our branch path. If it is and we are to
6928 if (path_entry
< path_size
&& data
->path
[path_entry
].branch
== p
)
6930 if (data
->path
[path_entry
].status
!= NOT_TAKEN
)
6933 /* Point to next entry in path, if any. */
6937 /* If this is a conditional jump, we can follow it if -fcse-follow-jumps
6938 was specified, we haven't reached our maximum path length, there are
6939 insns following the target of the jump, this is the only use of the
6940 jump label, and the target label is preceded by a BARRIER.
6942 Alternatively, we can follow the jump if it branches around a
6943 block of code and there are no other branches into the block.
6944 In this case invalidate_skipped_block will be called to invalidate any
6945 registers set in the block when following the jump. */
6947 else if ((follow_jumps
|| skip_blocks
) && path_size
< PARAM_VALUE (PARAM_MAX_CSE_PATH_LENGTH
) - 1
6948 && GET_CODE (p
) == JUMP_INSN
6949 && GET_CODE (PATTERN (p
)) == SET
6950 && GET_CODE (SET_SRC (PATTERN (p
))) == IF_THEN_ELSE
6951 && JUMP_LABEL (p
) != 0
6952 && LABEL_NUSES (JUMP_LABEL (p
)) == 1
6953 && NEXT_INSN (JUMP_LABEL (p
)) != 0)
6955 for (q
= PREV_INSN (JUMP_LABEL (p
)); q
; q
= PREV_INSN (q
))
6956 if ((GET_CODE (q
) != NOTE
6957 || NOTE_LINE_NUMBER (q
) == NOTE_INSN_LOOP_END
6958 || (PREV_INSN (q
) && GET_CODE (PREV_INSN (q
)) == CALL_INSN
6959 && find_reg_note (PREV_INSN (q
), REG_SETJMP
, NULL
)))
6960 && (GET_CODE (q
) != CODE_LABEL
|| LABEL_NUSES (q
) != 0))
6963 /* If we ran into a BARRIER, this code is an extension of the
6964 basic block when the branch is taken. */
6965 if (follow_jumps
&& q
!= 0 && GET_CODE (q
) == BARRIER
)
6967 /* Don't allow ourself to keep walking around an
6968 always-executed loop. */
6969 if (next_real_insn (q
) == next
)
6975 /* Similarly, don't put a branch in our path more than once. */
6976 for (i
= 0; i
< path_entry
; i
++)
6977 if (data
->path
[i
].branch
== p
)
6980 if (i
!= path_entry
)
6983 data
->path
[path_entry
].branch
= p
;
6984 data
->path
[path_entry
++].status
= TAKEN
;
6986 /* This branch now ends our path. It was possible that we
6987 didn't see this branch the last time around (when the
6988 insn in front of the target was a JUMP_INSN that was
6989 turned into a no-op). */
6990 path_size
= path_entry
;
6993 /* Mark block so we won't scan it again later. */
6994 PUT_MODE (NEXT_INSN (p
), QImode
);
6996 /* Detect a branch around a block of code. */
6997 else if (skip_blocks
&& q
!= 0 && GET_CODE (q
) != CODE_LABEL
)
7001 if (next_real_insn (q
) == next
)
7007 for (i
= 0; i
< path_entry
; i
++)
7008 if (data
->path
[i
].branch
== p
)
7011 if (i
!= path_entry
)
7014 /* This is no_labels_between_p (p, q) with an added check for
7015 reaching the end of a function (in case Q precedes P). */
7016 for (tmp
= NEXT_INSN (p
); tmp
&& tmp
!= q
; tmp
= NEXT_INSN (tmp
))
7017 if (GET_CODE (tmp
) == CODE_LABEL
)
7022 data
->path
[path_entry
].branch
= p
;
7023 data
->path
[path_entry
++].status
= AROUND
;
7025 path_size
= path_entry
;
7028 /* Mark block so we won't scan it again later. */
7029 PUT_MODE (NEXT_INSN (p
), QImode
);
7036 data
->low_cuid
= low_cuid
;
7037 data
->high_cuid
= high_cuid
;
7038 data
->nsets
= nsets
;
7041 /* If all jumps in the path are not taken, set our path length to zero
7042 so a rescan won't be done. */
7043 for (i
= path_size
- 1; i
>= 0; i
--)
7044 if (data
->path
[i
].status
!= NOT_TAKEN
)
7048 data
->path_size
= 0;
7050 data
->path_size
= path_size
;
7052 /* End the current branch path. */
7053 data
->path
[path_size
].branch
= 0;
7056 /* Perform cse on the instructions of a function.
7057 F is the first instruction.
7058 NREGS is one plus the highest pseudo-reg number used in the instruction.
7060 AFTER_LOOP is 1 if this is the cse call done after loop optimization
7061 (only if -frerun-cse-after-loop).
7063 Returns 1 if jump_optimize should be redone due to simplifications
7064 in conditional jump instructions. */
7067 cse_main (f
, nregs
, after_loop
, file
)
7073 struct cse_basic_block_data val
;
7077 val
.path
= xmalloc (sizeof (struct branch_path
)
7078 * PARAM_VALUE (PARAM_MAX_CSE_PATH_LENGTH
));
7080 cse_jumps_altered
= 0;
7081 recorded_label_ref
= 0;
7082 constant_pool_entries_cost
= 0;
7086 init_alias_analysis ();
7090 max_insn_uid
= get_max_uid ();
7092 reg_eqv_table
= (struct reg_eqv_elem
*)
7093 xmalloc (nregs
* sizeof (struct reg_eqv_elem
));
7095 #ifdef LOAD_EXTEND_OP
7097 /* Allocate scratch rtl here. cse_insn will fill in the memory reference
7098 and change the code and mode as appropriate. */
7099 memory_extend_rtx
= gen_rtx_ZERO_EXTEND (VOIDmode
, NULL_RTX
);
7102 /* Reset the counter indicating how many elements have been made
7104 n_elements_made
= 0;
7106 /* Find the largest uid. */
7108 max_uid
= get_max_uid ();
7109 uid_cuid
= (int *) xcalloc (max_uid
+ 1, sizeof (int));
7111 /* Compute the mapping from uids to cuids.
7112 CUIDs are numbers assigned to insns, like uids,
7113 except that cuids increase monotonically through the code.
7114 Don't assign cuids to line-number NOTEs, so that the distance in cuids
7115 between two insns is not affected by -g. */
7117 for (insn
= f
, i
= 0; insn
; insn
= NEXT_INSN (insn
))
7119 if (GET_CODE (insn
) != NOTE
7120 || NOTE_LINE_NUMBER (insn
) < 0)
7121 INSN_CUID (insn
) = ++i
;
7123 /* Give a line number note the same cuid as preceding insn. */
7124 INSN_CUID (insn
) = i
;
7127 ggc_push_context ();
7129 /* Loop over basic blocks.
7130 Compute the maximum number of qty's needed for each basic block
7131 (which is 2 for each SET). */
7136 cse_end_of_basic_block (insn
, &val
, flag_cse_follow_jumps
, after_loop
,
7137 flag_cse_skip_blocks
);
7139 /* If this basic block was already processed or has no sets, skip it. */
7140 if (val
.nsets
== 0 || GET_MODE (insn
) == QImode
)
7142 PUT_MODE (insn
, VOIDmode
);
7143 insn
= (val
.last
? NEXT_INSN (val
.last
) : 0);
7148 cse_basic_block_start
= val
.low_cuid
;
7149 cse_basic_block_end
= val
.high_cuid
;
7150 max_qty
= val
.nsets
* 2;
7153 fnotice (file
, ";; Processing block from %d to %d, %d sets.\n",
7154 INSN_UID (insn
), val
.last
? INSN_UID (val
.last
) : 0,
7157 /* Make MAX_QTY bigger to give us room to optimize
7158 past the end of this basic block, if that should prove useful. */
7164 /* If this basic block is being extended by following certain jumps,
7165 (see `cse_end_of_basic_block'), we reprocess the code from the start.
7166 Otherwise, we start after this basic block. */
7167 if (val
.path_size
> 0)
7168 cse_basic_block (insn
, val
.last
, val
.path
, 0);
7171 int old_cse_jumps_altered
= cse_jumps_altered
;
7174 /* When cse changes a conditional jump to an unconditional
7175 jump, we want to reprocess the block, since it will give
7176 us a new branch path to investigate. */
7177 cse_jumps_altered
= 0;
7178 temp
= cse_basic_block (insn
, val
.last
, val
.path
, ! after_loop
);
7179 if (cse_jumps_altered
== 0
7180 || (flag_cse_follow_jumps
== 0 && flag_cse_skip_blocks
== 0))
7183 cse_jumps_altered
|= old_cse_jumps_altered
;
7196 if (max_elements_made
< n_elements_made
)
7197 max_elements_made
= n_elements_made
;
7200 end_alias_analysis ();
7202 free (reg_eqv_table
);
7205 return cse_jumps_altered
|| recorded_label_ref
;
7208 /* Process a single basic block. FROM and TO and the limits of the basic
7209 block. NEXT_BRANCH points to the branch path when following jumps or
7210 a null path when not following jumps.
7212 AROUND_LOOP is nonzero if we are to try to cse around to the start of a
7213 loop. This is true when we are being called for the last time on a
7214 block and this CSE pass is before loop.c. */
7217 cse_basic_block (from
, to
, next_branch
, around_loop
)
7219 struct branch_path
*next_branch
;
7224 rtx libcall_insn
= NULL_RTX
;
7227 /* This array is undefined before max_reg, so only allocate
7228 the space actually needed and adjust the start. */
7231 = (struct qty_table_elem
*) xmalloc ((max_qty
- max_reg
)
7232 * sizeof (struct qty_table_elem
));
7233 qty_table
-= max_reg
;
7237 /* TO might be a label. If so, protect it from being deleted. */
7238 if (to
!= 0 && GET_CODE (to
) == CODE_LABEL
)
7241 for (insn
= from
; insn
!= to
; insn
= NEXT_INSN (insn
))
7243 enum rtx_code code
= GET_CODE (insn
);
7245 /* If we have processed 1,000 insns, flush the hash table to
7246 avoid extreme quadratic behavior. We must not include NOTEs
7247 in the count since there may be more of them when generating
7248 debugging information. If we clear the table at different
7249 times, code generated with -g -O might be different than code
7250 generated with -O but not -g.
7252 ??? This is a real kludge and needs to be done some other way.
7254 if (code
!= NOTE
&& num_insns
++ > 1000)
7256 flush_hash_table ();
7260 /* See if this is a branch that is part of the path. If so, and it is
7261 to be taken, do so. */
7262 if (next_branch
->branch
== insn
)
7264 enum taken status
= next_branch
++->status
;
7265 if (status
!= NOT_TAKEN
)
7267 if (status
== TAKEN
)
7268 record_jump_equiv (insn
, 1);
7270 invalidate_skipped_block (NEXT_INSN (insn
));
7272 /* Set the last insn as the jump insn; it doesn't affect cc0.
7273 Then follow this branch. */
7278 insn
= JUMP_LABEL (insn
);
7283 if (GET_MODE (insn
) == QImode
)
7284 PUT_MODE (insn
, VOIDmode
);
7286 if (GET_RTX_CLASS (code
) == 'i')
7290 /* Process notes first so we have all notes in canonical forms when
7291 looking for duplicate operations. */
7293 if (REG_NOTES (insn
))
7294 REG_NOTES (insn
) = cse_process_notes (REG_NOTES (insn
), NULL_RTX
);
7296 /* Track when we are inside in LIBCALL block. Inside such a block,
7297 we do not want to record destinations. The last insn of a
7298 LIBCALL block is not considered to be part of the block, since
7299 its destination is the result of the block and hence should be
7302 if (REG_NOTES (insn
) != 0)
7304 if ((p
= find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
)))
7305 libcall_insn
= XEXP (p
, 0);
7306 else if (find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
7310 cse_insn (insn
, libcall_insn
);
7312 /* If we haven't already found an insn where we added a LABEL_REF,
7314 if (GET_CODE (insn
) == INSN
&& ! recorded_label_ref
7315 && for_each_rtx (&PATTERN (insn
), check_for_label_ref
,
7317 recorded_label_ref
= 1;
7320 /* If INSN is now an unconditional jump, skip to the end of our
7321 basic block by pretending that we just did the last insn in the
7322 basic block. If we are jumping to the end of our block, show
7323 that we can have one usage of TO. */
7325 if (any_uncondjump_p (insn
))
7329 free (qty_table
+ max_reg
);
7333 if (JUMP_LABEL (insn
) == to
)
7336 /* Maybe TO was deleted because the jump is unconditional.
7337 If so, there is nothing left in this basic block. */
7338 /* ??? Perhaps it would be smarter to set TO
7339 to whatever follows this insn,
7340 and pretend the basic block had always ended here. */
7341 if (INSN_DELETED_P (to
))
7344 insn
= PREV_INSN (to
);
7347 /* See if it is ok to keep on going past the label
7348 which used to end our basic block. Remember that we incremented
7349 the count of that label, so we decrement it here. If we made
7350 a jump unconditional, TO_USAGE will be one; in that case, we don't
7351 want to count the use in that jump. */
7353 if (to
!= 0 && NEXT_INSN (insn
) == to
7354 && GET_CODE (to
) == CODE_LABEL
&& --LABEL_NUSES (to
) == to_usage
)
7356 struct cse_basic_block_data val
;
7359 insn
= NEXT_INSN (to
);
7361 /* If TO was the last insn in the function, we are done. */
7364 free (qty_table
+ max_reg
);
7368 /* If TO was preceded by a BARRIER we are done with this block
7369 because it has no continuation. */
7370 prev
= prev_nonnote_insn (to
);
7371 if (prev
&& GET_CODE (prev
) == BARRIER
)
7373 free (qty_table
+ max_reg
);
7377 /* Find the end of the following block. Note that we won't be
7378 following branches in this case. */
7381 val
.path
= xmalloc (sizeof (struct branch_path
)
7382 * PARAM_VALUE (PARAM_MAX_CSE_PATH_LENGTH
));
7383 cse_end_of_basic_block (insn
, &val
, 0, 0, 0);
7386 /* If the tables we allocated have enough space left
7387 to handle all the SETs in the next basic block,
7388 continue through it. Otherwise, return,
7389 and that block will be scanned individually. */
7390 if (val
.nsets
* 2 + next_qty
> max_qty
)
7393 cse_basic_block_start
= val
.low_cuid
;
7394 cse_basic_block_end
= val
.high_cuid
;
7397 /* Prevent TO from being deleted if it is a label. */
7398 if (to
!= 0 && GET_CODE (to
) == CODE_LABEL
)
7401 /* Back up so we process the first insn in the extension. */
7402 insn
= PREV_INSN (insn
);
7406 if (next_qty
> max_qty
)
7409 /* If we are running before loop.c, we stopped on a NOTE_INSN_LOOP_END, and
7410 the previous insn is the only insn that branches to the head of a loop,
7411 we can cse into the loop. Don't do this if we changed the jump
7412 structure of a loop unless we aren't going to be following jumps. */
7414 insn
= prev_nonnote_insn (to
);
7415 if ((cse_jumps_altered
== 0
7416 || (flag_cse_follow_jumps
== 0 && flag_cse_skip_blocks
== 0))
7417 && around_loop
&& to
!= 0
7418 && GET_CODE (to
) == NOTE
&& NOTE_LINE_NUMBER (to
) == NOTE_INSN_LOOP_END
7419 && GET_CODE (insn
) == JUMP_INSN
7420 && JUMP_LABEL (insn
) != 0
7421 && LABEL_NUSES (JUMP_LABEL (insn
)) == 1)
7422 cse_around_loop (JUMP_LABEL (insn
));
7424 free (qty_table
+ max_reg
);
7426 return to
? NEXT_INSN (to
) : 0;
7429 /* Called via for_each_rtx to see if an insn is using a LABEL_REF for which
7430 there isn't a REG_LABEL note. Return one if so. DATA is the insn. */
7433 check_for_label_ref (rtl
, data
)
7437 rtx insn
= (rtx
) data
;
7439 /* If this insn uses a LABEL_REF and there isn't a REG_LABEL note for it,
7440 we must rerun jump since it needs to place the note. If this is a
7441 LABEL_REF for a CODE_LABEL that isn't in the insn chain, don't do this
7442 since no REG_LABEL will be added. */
7443 return (GET_CODE (*rtl
) == LABEL_REF
7444 && ! LABEL_REF_NONLOCAL_P (*rtl
)
7445 && LABEL_P (XEXP (*rtl
, 0))
7446 && INSN_UID (XEXP (*rtl
, 0)) != 0
7447 && ! find_reg_note (insn
, REG_LABEL
, XEXP (*rtl
, 0)));
7450 /* Count the number of times registers are used (not set) in X.
7451 COUNTS is an array in which we accumulate the count, INCR is how much
7452 we count each register usage.
7454 Don't count a usage of DEST, which is the SET_DEST of a SET which
7455 contains X in its SET_SRC. This is because such a SET does not
7456 modify the liveness of DEST. */
7459 count_reg_usage (x
, counts
, dest
, incr
)
7473 switch (code
= GET_CODE (x
))
7477 counts
[REGNO (x
)] += incr
;
7491 /* If we are clobbering a MEM, mark any registers inside the address
7493 if (GET_CODE (XEXP (x
, 0)) == MEM
)
7494 count_reg_usage (XEXP (XEXP (x
, 0), 0), counts
, NULL_RTX
, incr
);
7498 /* Unless we are setting a REG, count everything in SET_DEST. */
7499 if (GET_CODE (SET_DEST (x
)) != REG
)
7500 count_reg_usage (SET_DEST (x
), counts
, NULL_RTX
, incr
);
7501 count_reg_usage (SET_SRC (x
), counts
,
7507 count_reg_usage (CALL_INSN_FUNCTION_USAGE (x
), counts
, NULL_RTX
, incr
);
7512 count_reg_usage (PATTERN (x
), counts
, NULL_RTX
, incr
);
7514 /* Things used in a REG_EQUAL note aren't dead since loop may try to
7517 note
= find_reg_equal_equiv_note (x
);
7520 rtx eqv
= XEXP (note
, 0);
7522 if (GET_CODE (eqv
) == EXPR_LIST
)
7523 /* This REG_EQUAL note describes the result of a function call.
7524 Process all the arguments. */
7527 count_reg_usage (XEXP (eqv
, 0), counts
, NULL_RTX
, incr
);
7528 eqv
= XEXP (eqv
, 1);
7530 while (eqv
&& GET_CODE (eqv
) == EXPR_LIST
);
7532 count_reg_usage (eqv
, counts
, NULL_RTX
, incr
);
7537 if (REG_NOTE_KIND (x
) == REG_EQUAL
7538 || (REG_NOTE_KIND (x
) != REG_NONNEG
&& GET_CODE (XEXP (x
,0)) == USE
)
7539 /* FUNCTION_USAGE expression lists may include (CLOBBER (mem /u)),
7540 involving registers in the address. */
7541 || GET_CODE (XEXP (x
, 0)) == CLOBBER
)
7542 count_reg_usage (XEXP (x
, 0), counts
, NULL_RTX
, incr
);
7544 count_reg_usage (XEXP (x
, 1), counts
, NULL_RTX
, incr
);
7554 fmt
= GET_RTX_FORMAT (code
);
7555 for (i
= GET_RTX_LENGTH (code
) - 1; i
>= 0; i
--)
7558 count_reg_usage (XEXP (x
, i
), counts
, dest
, incr
);
7559 else if (fmt
[i
] == 'E')
7560 for (j
= XVECLEN (x
, i
) - 1; j
>= 0; j
--)
7561 count_reg_usage (XVECEXP (x
, i
, j
), counts
, dest
, incr
);
7565 /* Return true if set is live. */
7567 set_live_p (set
, insn
, counts
)
7569 rtx insn ATTRIBUTE_UNUSED
; /* Only used with HAVE_cc0. */
7576 if (set_noop_p (set
))
7580 else if (GET_CODE (SET_DEST (set
)) == CC0
7581 && !side_effects_p (SET_SRC (set
))
7582 && ((tem
= next_nonnote_insn (insn
)) == 0
7584 || !reg_referenced_p (cc0_rtx
, PATTERN (tem
))))
7587 else if (GET_CODE (SET_DEST (set
)) != REG
7588 || REGNO (SET_DEST (set
)) < FIRST_PSEUDO_REGISTER
7589 || counts
[REGNO (SET_DEST (set
))] != 0
7590 || side_effects_p (SET_SRC (set
))
7591 /* An ADDRESSOF expression can turn into a use of the
7592 internal arg pointer, so always consider the
7593 internal arg pointer live. If it is truly dead,
7594 flow will delete the initializing insn. */
7595 || (SET_DEST (set
) == current_function_internal_arg_pointer
))
7600 /* Return true if insn is live. */
7603 insn_live_p (insn
, counts
)
7608 if (flag_non_call_exceptions
&& may_trap_p (PATTERN (insn
)))
7610 else if (GET_CODE (PATTERN (insn
)) == SET
)
7611 return set_live_p (PATTERN (insn
), insn
, counts
);
7612 else if (GET_CODE (PATTERN (insn
)) == PARALLEL
)
7614 for (i
= XVECLEN (PATTERN (insn
), 0) - 1; i
>= 0; i
--)
7616 rtx elt
= XVECEXP (PATTERN (insn
), 0, i
);
7618 if (GET_CODE (elt
) == SET
)
7620 if (set_live_p (elt
, insn
, counts
))
7623 else if (GET_CODE (elt
) != CLOBBER
&& GET_CODE (elt
) != USE
)
7632 /* Return true if libcall is dead as a whole. */
7635 dead_libcall_p (insn
, counts
)
7641 /* See if there's a REG_EQUAL note on this insn and try to
7642 replace the source with the REG_EQUAL expression.
7644 We assume that insns with REG_RETVALs can only be reg->reg
7645 copies at this point. */
7646 note
= find_reg_note (insn
, REG_EQUAL
, NULL_RTX
);
7650 set
= single_set (insn
);
7654 new = simplify_rtx (XEXP (note
, 0));
7656 new = XEXP (note
, 0);
7658 /* While changing insn, we must update the counts accordingly. */
7659 count_reg_usage (insn
, counts
, NULL_RTX
, -1);
7661 if (validate_change (insn
, &SET_SRC (set
), new, 0))
7663 count_reg_usage (insn
, counts
, NULL_RTX
, 1);
7664 remove_note (insn
, find_reg_note (insn
, REG_RETVAL
, NULL_RTX
));
7665 remove_note (insn
, note
);
7669 if (CONSTANT_P (new))
7671 new = force_const_mem (GET_MODE (SET_DEST (set
)), new);
7672 if (new && validate_change (insn
, &SET_SRC (set
), new, 0))
7674 count_reg_usage (insn
, counts
, NULL_RTX
, 1);
7675 remove_note (insn
, find_reg_note (insn
, REG_RETVAL
, NULL_RTX
));
7676 remove_note (insn
, note
);
7681 count_reg_usage (insn
, counts
, NULL_RTX
, 1);
7685 /* Scan all the insns and delete any that are dead; i.e., they store a register
7686 that is never used or they copy a register to itself.
7688 This is used to remove insns made obviously dead by cse, loop or other
7689 optimizations. It improves the heuristics in loop since it won't try to
7690 move dead invariants out of loops or make givs for dead quantities. The
7691 remaining passes of the compilation are also sped up. */
7694 delete_trivially_dead_insns (insns
, nreg
)
7700 int in_libcall
= 0, dead_libcall
= 0;
7701 int ndead
= 0, nlastdead
, niterations
= 0;
7703 timevar_push (TV_DELETE_TRIVIALLY_DEAD
);
7704 /* First count the number of times each register is used. */
7705 counts
= (int *) xcalloc (nreg
, sizeof (int));
7706 for (insn
= next_real_insn (insns
); insn
; insn
= next_real_insn (insn
))
7707 count_reg_usage (insn
, counts
, NULL_RTX
, 1);
7713 /* Go from the last insn to the first and delete insns that only set unused
7714 registers or copy a register to itself. As we delete an insn, remove
7715 usage counts for registers it uses.
7717 The first jump optimization pass may leave a real insn as the last
7718 insn in the function. We must not skip that insn or we may end
7719 up deleting code that is not really dead. */
7720 insn
= get_last_insn ();
7721 if (! INSN_P (insn
))
7722 insn
= prev_real_insn (insn
);
7724 for (; insn
; insn
= prev
)
7728 prev
= prev_real_insn (insn
);
7730 /* Don't delete any insns that are part of a libcall block unless
7731 we can delete the whole libcall block.
7733 Flow or loop might get confused if we did that. Remember
7734 that we are scanning backwards. */
7735 if (find_reg_note (insn
, REG_RETVAL
, NULL_RTX
))
7739 dead_libcall
= dead_libcall_p (insn
, counts
);
7741 else if (in_libcall
)
7742 live_insn
= ! dead_libcall
;
7744 live_insn
= insn_live_p (insn
, counts
);
7746 /* If this is a dead insn, delete it and show registers in it aren't
7751 count_reg_usage (insn
, counts
, NULL_RTX
, -1);
7752 delete_insn_and_edges (insn
);
7756 if (find_reg_note (insn
, REG_LIBCALL
, NULL_RTX
))
7763 while (ndead
!= nlastdead
);
7765 if (rtl_dump_file
&& ndead
)
7766 fprintf (rtl_dump_file
, "Deleted %i trivially dead insns; %i iterations\n",
7767 ndead
, niterations
);
7770 timevar_pop (TV_DELETE_TRIVIALLY_DEAD
);