1 /* Expands front end tree to back end RTL for GCC
2 Copyright (C) 1987-2017 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /* This file handles the generation of rtl code from tree structure
21 above the level of expressions, using subroutines in exp*.c and emit-rtl.c.
22 The functions whose names start with `expand_' are called by the
23 expander to generate RTL instructions for various kinds of constructs. */
27 #include "coretypes.h"
40 #include "pretty-print.h"
41 #include "diagnostic-core.h"
43 #include "fold-const.h"
45 #include "stor-layout.h"
50 #include "langhooks.h"
58 /* Functions and data structures for expanding case statements. */
60 /* Case label structure, used to hold info on labels within case
61 statements. We handle "range" labels; for a single-value label
62 as in C, the high and low limits are the same.
64 We start with a vector of case nodes sorted in ascending order, and
65 the default label as the last element in the vector.
67 Switch statements are expanded in jump table form.
71 struct simple_case_node
73 simple_case_node (tree low
, tree high
, tree code_label
):
74 m_low (low
), m_high (high
), m_code_label (code_label
)
77 /* Lowest index value for this label. */
79 /* Highest index value for this label. */
81 /* Label to jump to when node matches. */
85 extern basic_block
label_to_block_fn (struct function
*, tree
);
87 static bool check_unique_operand_names (tree
, tree
, tree
);
88 static char *resolve_operand_name_1 (char *, tree
, tree
, tree
);
90 /* Return the rtx-label that corresponds to a LABEL_DECL,
91 creating it if necessary. */
94 label_rtx (tree label
)
96 gcc_assert (TREE_CODE (label
) == LABEL_DECL
);
98 if (!DECL_RTL_SET_P (label
))
100 rtx_code_label
*r
= gen_label_rtx ();
101 SET_DECL_RTL (label
, r
);
102 if (FORCED_LABEL (label
) || DECL_NONLOCAL (label
))
103 LABEL_PRESERVE_P (r
) = 1;
106 return as_a
<rtx_insn
*> (DECL_RTL (label
));
109 /* As above, but also put it on the forced-reference list of the
110 function that contains it. */
112 force_label_rtx (tree label
)
114 rtx_insn
*ref
= label_rtx (label
);
115 tree function
= decl_function_context (label
);
117 gcc_assert (function
);
119 vec_safe_push (forced_labels
, ref
);
123 /* As label_rtx, but ensures (in check build), that returned value is
124 an existing label (i.e. rtx with code CODE_LABEL). */
126 jump_target_rtx (tree label
)
128 return as_a
<rtx_code_label
*> (label_rtx (label
));
131 /* Add an unconditional jump to LABEL as the next sequential instruction. */
134 emit_jump (rtx label
)
136 do_pending_stack_adjust ();
137 emit_jump_insn (targetm
.gen_jump (label
));
141 /* Handle goto statements and the labels that they can go to. */
143 /* Specify the location in the RTL code of a label LABEL,
144 which is a LABEL_DECL tree node.
146 This is used for the kind of label that the user can jump to with a
147 goto statement, and for alternatives of a switch or case statement.
148 RTL labels generated for loops and conditionals don't go through here;
149 they are generated directly at the RTL level, by other functions below.
151 Note that this has nothing to do with defining label *names*.
152 Languages vary in how they do that and what that even means. */
155 expand_label (tree label
)
157 rtx_code_label
*label_r
= jump_target_rtx (label
);
159 do_pending_stack_adjust ();
160 emit_label (label_r
);
161 if (DECL_NAME (label
))
162 LABEL_NAME (DECL_RTL (label
)) = IDENTIFIER_POINTER (DECL_NAME (label
));
164 if (DECL_NONLOCAL (label
))
166 expand_builtin_setjmp_receiver (NULL
);
167 nonlocal_goto_handler_labels
168 = gen_rtx_INSN_LIST (VOIDmode
, label_r
,
169 nonlocal_goto_handler_labels
);
172 if (FORCED_LABEL (label
))
173 vec_safe_push
<rtx_insn
*> (forced_labels
, label_r
);
175 if (DECL_NONLOCAL (label
) || FORCED_LABEL (label
))
176 maybe_set_first_label_num (label_r
);
179 /* Parse the output constraint pointed to by *CONSTRAINT_P. It is the
180 OPERAND_NUMth output operand, indexed from zero. There are NINPUTS
181 inputs and NOUTPUTS outputs to this extended-asm. Upon return,
182 *ALLOWS_MEM will be TRUE iff the constraint allows the use of a
183 memory operand. Similarly, *ALLOWS_REG will be TRUE iff the
184 constraint allows the use of a register operand. And, *IS_INOUT
185 will be true if the operand is read-write, i.e., if it is used as
186 an input as well as an output. If *CONSTRAINT_P is not in
187 canonical form, it will be made canonical. (Note that `+' will be
188 replaced with `=' as part of this process.)
190 Returns TRUE if all went well; FALSE if an error occurred. */
193 parse_output_constraint (const char **constraint_p
, int operand_num
,
194 int ninputs
, int noutputs
, bool *allows_mem
,
195 bool *allows_reg
, bool *is_inout
)
197 const char *constraint
= *constraint_p
;
200 /* Assume the constraint doesn't allow the use of either a register
205 /* Allow the `=' or `+' to not be at the beginning of the string,
206 since it wasn't explicitly documented that way, and there is a
207 large body of code that puts it last. Swap the character to
208 the front, so as not to uglify any place else. */
209 p
= strchr (constraint
, '=');
211 p
= strchr (constraint
, '+');
213 /* If the string doesn't contain an `=', issue an error
217 error ("output operand constraint lacks %<=%>");
221 /* If the constraint begins with `+', then the operand is both read
222 from and written to. */
223 *is_inout
= (*p
== '+');
225 /* Canonicalize the output constraint so that it begins with `='. */
226 if (p
!= constraint
|| *is_inout
)
229 size_t c_len
= strlen (constraint
);
232 warning (0, "output constraint %qc for operand %d "
233 "is not at the beginning",
236 /* Make a copy of the constraint. */
237 buf
= XALLOCAVEC (char, c_len
+ 1);
238 strcpy (buf
, constraint
);
239 /* Swap the first character and the `=' or `+'. */
240 buf
[p
- constraint
] = buf
[0];
241 /* Make sure the first character is an `='. (Until we do this,
242 it might be a `+'.) */
244 /* Replace the constraint with the canonicalized string. */
245 *constraint_p
= ggc_alloc_string (buf
, c_len
);
246 constraint
= *constraint_p
;
249 /* Loop through the constraint string. */
250 for (p
= constraint
+ 1; *p
; p
+= CONSTRAINT_LEN (*p
, p
))
255 error ("operand constraint contains incorrectly positioned "
260 if (operand_num
+ 1 == ninputs
+ noutputs
)
262 error ("%<%%%> constraint used with last operand");
267 case '?': case '!': case '*': case '&': case '#':
269 case 'E': case 'F': case 'G': case 'H':
270 case 's': case 'i': case 'n':
271 case 'I': case 'J': case 'K': case 'L': case 'M':
272 case 'N': case 'O': case 'P': case ',':
275 case '0': case '1': case '2': case '3': case '4':
276 case '5': case '6': case '7': case '8': case '9':
278 error ("matching constraint not valid in output operand");
282 /* ??? Before flow, auto inc/dec insns are not supposed to exist,
283 excepting those that expand_call created. So match memory
296 enum constraint_num cn
= lookup_constraint (p
);
297 if (reg_class_for_constraint (cn
) != NO_REGS
298 || insn_extra_address_constraint (cn
))
300 else if (insn_extra_memory_constraint (cn
))
303 insn_extra_constraint_allows_reg_mem (cn
, allows_reg
, allows_mem
);
310 /* Similar, but for input constraints. */
313 parse_input_constraint (const char **constraint_p
, int input_num
,
314 int ninputs
, int noutputs
, int ninout
,
315 const char * const * constraints
,
316 bool *allows_mem
, bool *allows_reg
)
318 const char *constraint
= *constraint_p
;
319 const char *orig_constraint
= constraint
;
320 size_t c_len
= strlen (constraint
);
322 bool saw_match
= false;
324 /* Assume the constraint doesn't allow the use of either
325 a register or memory. */
329 /* Make sure constraint has neither `=', `+', nor '&'. */
331 for (j
= 0; j
< c_len
; j
+= CONSTRAINT_LEN (constraint
[j
], constraint
+j
))
332 switch (constraint
[j
])
334 case '+': case '=': case '&':
335 if (constraint
== orig_constraint
)
337 error ("input operand constraint contains %qc", constraint
[j
]);
343 if (constraint
== orig_constraint
344 && input_num
+ 1 == ninputs
- ninout
)
346 error ("%<%%%> constraint used with last operand");
352 case '?': case '!': case '*': case '#':
354 case 'E': case 'F': case 'G': case 'H':
355 case 's': case 'i': case 'n':
356 case 'I': case 'J': case 'K': case 'L': case 'M':
357 case 'N': case 'O': case 'P': case ',':
360 /* Whether or not a numeric constraint allows a register is
361 decided by the matching constraint, and so there is no need
362 to do anything special with them. We must handle them in
363 the default case, so that we don't unnecessarily force
364 operands to memory. */
365 case '0': case '1': case '2': case '3': case '4':
366 case '5': case '6': case '7': case '8': case '9':
373 match
= strtoul (constraint
+ j
, &end
, 10);
374 if (match
>= (unsigned long) noutputs
)
376 error ("matching constraint references invalid operand number");
380 /* Try and find the real constraint for this dup. Only do this
381 if the matching constraint is the only alternative. */
383 && (j
== 0 || (j
== 1 && constraint
[0] == '%')))
385 constraint
= constraints
[match
];
386 *constraint_p
= constraint
;
387 c_len
= strlen (constraint
);
389 /* ??? At the end of the loop, we will skip the first part of
390 the matched constraint. This assumes not only that the
391 other constraint is an output constraint, but also that
392 the '=' or '+' come first. */
396 j
= end
- constraint
;
397 /* Anticipate increment at end of loop. */
408 if (! ISALPHA (constraint
[j
]))
410 error ("invalid punctuation %qc in constraint", constraint
[j
]);
413 enum constraint_num cn
= lookup_constraint (constraint
+ j
);
414 if (reg_class_for_constraint (cn
) != NO_REGS
415 || insn_extra_address_constraint (cn
))
417 else if (insn_extra_memory_constraint (cn
)
418 || insn_extra_special_memory_constraint (cn
))
421 insn_extra_constraint_allows_reg_mem (cn
, allows_reg
, allows_mem
);
425 if (saw_match
&& !*allows_reg
)
426 warning (0, "matching constraint does not allow a register");
431 /* Return DECL iff there's an overlap between *REGS and DECL, where DECL
432 can be an asm-declared register. Called via walk_tree. */
435 decl_overlaps_hard_reg_set_p (tree
*declp
, int *walk_subtrees ATTRIBUTE_UNUSED
,
439 const HARD_REG_SET
*const regs
= (const HARD_REG_SET
*) data
;
443 if (DECL_HARD_REGISTER (decl
)
444 && REG_P (DECL_RTL (decl
))
445 && REGNO (DECL_RTL (decl
)) < FIRST_PSEUDO_REGISTER
)
447 rtx reg
= DECL_RTL (decl
);
449 if (overlaps_hard_reg_set_p (*regs
, GET_MODE (reg
), REGNO (reg
)))
454 else if (TYPE_P (decl
) || TREE_CODE (decl
) == PARM_DECL
)
459 /* If there is an overlap between *REGS and DECL, return the first overlap
462 tree_overlaps_hard_reg_set (tree decl
, HARD_REG_SET
*regs
)
464 return walk_tree (&decl
, decl_overlaps_hard_reg_set_p
, regs
, NULL
);
468 /* A subroutine of expand_asm_operands. Check that all operand names
469 are unique. Return true if so. We rely on the fact that these names
470 are identifiers, and so have been canonicalized by get_identifier,
471 so all we need are pointer comparisons. */
474 check_unique_operand_names (tree outputs
, tree inputs
, tree labels
)
476 tree i
, j
, i_name
= NULL_TREE
;
478 for (i
= outputs
; i
; i
= TREE_CHAIN (i
))
480 i_name
= TREE_PURPOSE (TREE_PURPOSE (i
));
484 for (j
= TREE_CHAIN (i
); j
; j
= TREE_CHAIN (j
))
485 if (simple_cst_equal (i_name
, TREE_PURPOSE (TREE_PURPOSE (j
))))
489 for (i
= inputs
; i
; i
= TREE_CHAIN (i
))
491 i_name
= TREE_PURPOSE (TREE_PURPOSE (i
));
495 for (j
= TREE_CHAIN (i
); j
; j
= TREE_CHAIN (j
))
496 if (simple_cst_equal (i_name
, TREE_PURPOSE (TREE_PURPOSE (j
))))
498 for (j
= outputs
; j
; j
= TREE_CHAIN (j
))
499 if (simple_cst_equal (i_name
, TREE_PURPOSE (TREE_PURPOSE (j
))))
503 for (i
= labels
; i
; i
= TREE_CHAIN (i
))
505 i_name
= TREE_PURPOSE (i
);
509 for (j
= TREE_CHAIN (i
); j
; j
= TREE_CHAIN (j
))
510 if (simple_cst_equal (i_name
, TREE_PURPOSE (j
)))
512 for (j
= inputs
; j
; j
= TREE_CHAIN (j
))
513 if (simple_cst_equal (i_name
, TREE_PURPOSE (TREE_PURPOSE (j
))))
520 error ("duplicate asm operand name %qs", TREE_STRING_POINTER (i_name
));
524 /* Resolve the names of the operands in *POUTPUTS and *PINPUTS to numbers,
525 and replace the name expansions in STRING and in the constraints to
526 those numbers. This is generally done in the front end while creating
527 the ASM_EXPR generic tree that eventually becomes the GIMPLE_ASM. */
530 resolve_asm_operand_names (tree string
, tree outputs
, tree inputs
, tree labels
)
537 check_unique_operand_names (outputs
, inputs
, labels
);
539 /* Substitute [<name>] in input constraint strings. There should be no
540 named operands in output constraints. */
541 for (t
= inputs
; t
; t
= TREE_CHAIN (t
))
543 c
= TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t
)));
544 if (strchr (c
, '[') != NULL
)
546 p
= buffer
= xstrdup (c
);
547 while ((p
= strchr (p
, '[')) != NULL
)
548 p
= resolve_operand_name_1 (p
, outputs
, inputs
, NULL
);
549 TREE_VALUE (TREE_PURPOSE (t
))
550 = build_string (strlen (buffer
), buffer
);
555 /* Now check for any needed substitutions in the template. */
556 c
= TREE_STRING_POINTER (string
);
557 while ((c
= strchr (c
, '%')) != NULL
)
561 else if (ISALPHA (c
[1]) && c
[2] == '[')
565 c
+= 1 + (c
[1] == '%');
572 /* OK, we need to make a copy so we can perform the substitutions.
573 Assume that we will not need extra space--we get to remove '['
574 and ']', which means we cannot have a problem until we have more
575 than 999 operands. */
576 buffer
= xstrdup (TREE_STRING_POINTER (string
));
577 p
= buffer
+ (c
- TREE_STRING_POINTER (string
));
579 while ((p
= strchr (p
, '%')) != NULL
)
583 else if (ISALPHA (p
[1]) && p
[2] == '[')
587 p
+= 1 + (p
[1] == '%');
591 p
= resolve_operand_name_1 (p
, outputs
, inputs
, labels
);
594 string
= build_string (strlen (buffer
), buffer
);
601 /* A subroutine of resolve_operand_names. P points to the '[' for a
602 potential named operand of the form [<name>]. In place, replace
603 the name and brackets with a number. Return a pointer to the
604 balance of the string after substitution. */
607 resolve_operand_name_1 (char *p
, tree outputs
, tree inputs
, tree labels
)
613 /* Collect the operand name. */
614 q
= strchr (++p
, ']');
617 error ("missing close brace for named operand");
618 return strchr (p
, '\0');
622 /* Resolve the name to a number. */
623 for (op
= 0, t
= outputs
; t
; t
= TREE_CHAIN (t
), op
++)
625 tree name
= TREE_PURPOSE (TREE_PURPOSE (t
));
626 if (name
&& strcmp (TREE_STRING_POINTER (name
), p
) == 0)
629 for (t
= inputs
; t
; t
= TREE_CHAIN (t
), op
++)
631 tree name
= TREE_PURPOSE (TREE_PURPOSE (t
));
632 if (name
&& strcmp (TREE_STRING_POINTER (name
), p
) == 0)
635 for (t
= labels
; t
; t
= TREE_CHAIN (t
), op
++)
637 tree name
= TREE_PURPOSE (t
);
638 if (name
&& strcmp (TREE_STRING_POINTER (name
), p
) == 0)
642 error ("undefined named operand %qs", identifier_to_locale (p
));
646 /* Replace the name with the number. Unfortunately, not all libraries
647 get the return value of sprintf correct, so search for the end of the
648 generated string by hand. */
649 sprintf (--p
, "%d", op
);
650 p
= strchr (p
, '\0');
652 /* Verify the no extra buffer space assumption. */
655 /* Shift the rest of the buffer down to fill the gap. */
656 memmove (p
, q
+ 1, strlen (q
+ 1) + 1);
662 /* Generate RTL to return directly from the current function.
663 (That is, we bypass any return value.) */
666 expand_naked_return (void)
668 rtx_code_label
*end_label
;
670 clear_pending_stack_adjust ();
671 do_pending_stack_adjust ();
673 end_label
= naked_return_label
;
675 end_label
= naked_return_label
= gen_label_rtx ();
677 emit_jump (end_label
);
680 /* Generate code to jump to LABEL if OP0 and OP1 are equal in mode MODE. PROB
681 is the probability of jumping to LABEL. */
683 do_jump_if_equal (machine_mode mode
, rtx op0
, rtx op1
, rtx_code_label
*label
,
684 int unsignedp
, profile_probability prob
)
686 do_compare_rtx_and_jump (op0
, op1
, EQ
, unsignedp
, mode
,
687 NULL_RTX
, NULL
, label
, prob
);
690 /* Return the sum of probabilities of outgoing edges of basic block BB. */
692 static profile_probability
693 get_outgoing_edge_probs (basic_block bb
)
697 profile_probability prob_sum
= profile_probability::never ();
699 return profile_probability::never ();
700 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
701 prob_sum
+= e
->probability
;
705 /* Computes the conditional probability of jumping to a target if the branch
706 instruction is executed.
707 TARGET_PROB is the estimated probability of jumping to a target relative
708 to some basic block BB.
709 BASE_PROB is the probability of reaching the branch instruction relative
710 to the same basic block BB. */
712 static inline profile_probability
713 conditional_probability (profile_probability target_prob
,
714 profile_probability base_prob
)
716 return target_prob
/ base_prob
;
719 /* Generate a dispatch tabler, switching on INDEX_EXPR and jumping to
720 one of the labels in CASE_LIST or to the DEFAULT_LABEL.
721 MINVAL, MAXVAL, and RANGE are the extrema and range of the case
722 labels in CASE_LIST. STMT_BB is the basic block containing the statement.
724 First, a jump insn is emitted. First we try "casesi". If that
725 fails, try "tablejump". A target *must* have one of them (or both).
727 Then, a table with the target labels is emitted.
729 The process is unaware of the CFG. The caller has to fix up
730 the CFG itself. This is done in cfgexpand.c. */
733 emit_case_dispatch_table (tree index_expr
, tree index_type
,
734 auto_vec
<simple_case_node
> &case_list
,
736 edge default_edge
, tree minval
, tree maxval
,
737 tree range
, basic_block stmt_bb
)
741 rtx_insn
*fallback_label
= label_rtx (case_list
[0].m_code_label
);
742 rtx_code_label
*table_label
= gen_label_rtx ();
743 bool has_gaps
= false;
744 profile_probability default_prob
= default_edge
? default_edge
->probability
745 : profile_probability::never ();
746 profile_probability base
= get_outgoing_edge_probs (stmt_bb
);
747 bool try_with_tablejump
= false;
749 profile_probability new_default_prob
= conditional_probability (default_prob
,
752 if (! try_casesi (index_type
, index_expr
, minval
, range
,
753 table_label
, default_label
, fallback_label
,
756 /* Index jumptables from zero for suitable values of minval to avoid
757 a subtraction. For the rationale see:
758 "http://gcc.gnu.org/ml/gcc-patches/2001-10/msg01234.html". */
759 if (optimize_insn_for_speed_p ()
760 && compare_tree_int (minval
, 0) > 0
761 && compare_tree_int (minval
, 3) < 0)
763 minval
= build_int_cst (index_type
, 0);
767 try_with_tablejump
= true;
770 /* Get table of labels to jump to, in order of case index. */
772 ncases
= tree_to_shwi (range
) + 1;
773 labelvec
= XALLOCAVEC (rtx
, ncases
);
774 memset (labelvec
, 0, ncases
* sizeof (rtx
));
776 for (unsigned j
= 0; j
< case_list
.length (); j
++)
778 simple_case_node
*n
= &case_list
[j
];
779 /* Compute the low and high bounds relative to the minimum
780 value since that should fit in a HOST_WIDE_INT while the
781 actual values may not. */
783 = tree_to_uhwi (fold_build2 (MINUS_EXPR
, index_type
,
786 = tree_to_uhwi (fold_build2 (MINUS_EXPR
, index_type
,
790 for (i
= i_low
; i
<= i_high
; i
++)
792 = gen_rtx_LABEL_REF (Pmode
, label_rtx (n
->m_code_label
));
795 /* The dispatch table may contain gaps, including at the beginning of
796 the table if we tried to avoid the minval subtraction. We fill the
797 dispatch table slots associated with the gaps with the default case label.
798 However, in the event the default case is unreachable, we then use
799 any label from one of the case statements. */
800 rtx gap_label
= (default_label
) ? default_label
: fallback_label
;
802 for (i
= 0; i
< ncases
; i
++)
803 if (labelvec
[i
] == 0)
806 labelvec
[i
] = gen_rtx_LABEL_REF (Pmode
, gap_label
);
809 if (has_gaps
&& default_label
)
811 /* There is at least one entry in the jump table that jumps
812 to default label. The default label can either be reached
813 through the indirect jump or the direct conditional jump
814 before that. Split the probability of reaching the
815 default label among these two jumps. */
817 = conditional_probability (default_prob
.apply_scale (1, 2), base
);
818 default_prob
= default_prob
.apply_scale (1, 2);
819 base
-= default_prob
;
823 base
-= default_prob
;
824 default_prob
= profile_probability::never ();
828 default_edge
->probability
= default_prob
;
830 /* We have altered the probability of the default edge. So the probabilities
831 of all other edges need to be adjusted so that it sums up to
833 if (base
> profile_probability::never ())
837 FOR_EACH_EDGE (e
, ei
, stmt_bb
->succs
)
838 e
->probability
/= base
;
841 if (try_with_tablejump
)
843 bool ok
= try_tablejump (index_type
, index_expr
, minval
, range
,
844 table_label
, default_label
, new_default_prob
);
847 /* Output the table. */
848 emit_label (table_label
);
850 if (CASE_VECTOR_PC_RELATIVE
|| flag_pic
)
851 emit_jump_table_data (gen_rtx_ADDR_DIFF_VEC (CASE_VECTOR_MODE
,
852 gen_rtx_LABEL_REF (Pmode
,
854 gen_rtvec_v (ncases
, labelvec
),
855 const0_rtx
, const0_rtx
));
857 emit_jump_table_data (gen_rtx_ADDR_VEC (CASE_VECTOR_MODE
,
858 gen_rtvec_v (ncases
, labelvec
)));
860 /* Record no drop-through after the table. */
864 /* Terminate a case Ada or switch (C) statement
865 in which ORIG_INDEX is the expression to be tested.
866 If ORIG_TYPE is not NULL, it is the original ORIG_INDEX
867 type as given in the source before any compiler conversions.
868 Generate the code to test it and jump to the right place. */
871 expand_case (gswitch
*stmt
)
873 tree minval
= NULL_TREE
, maxval
= NULL_TREE
, range
= NULL_TREE
;
874 rtx_code_label
*default_label
;
877 int ncases
= gimple_switch_num_labels (stmt
);
878 tree index_expr
= gimple_switch_index (stmt
);
879 tree index_type
= TREE_TYPE (index_expr
);
881 basic_block bb
= gimple_bb (stmt
);
883 auto_vec
<simple_case_node
> case_list
;
885 /* An ERROR_MARK occurs for various reasons including invalid data type.
886 ??? Can this still happen, with GIMPLE and all? */
887 if (index_type
== error_mark_node
)
890 /* cleanup_tree_cfg removes all SWITCH_EXPR with their index
891 expressions being INTEGER_CST. */
892 gcc_assert (TREE_CODE (index_expr
) != INTEGER_CST
);
894 /* Optimization of switch statements with only one label has already
895 occurred, so we should never see them at this point. */
896 gcc_assert (ncases
> 1);
898 do_pending_stack_adjust ();
900 /* Find the default case target label. */
901 tree default_lab
= CASE_LABEL (gimple_switch_default_label (stmt
));
902 default_label
= jump_target_rtx (default_lab
);
903 basic_block default_bb
= label_to_block_fn (cfun
, default_lab
);
904 edge default_edge
= find_edge (bb
, default_bb
);
906 /* Get upper and lower bounds of case values. */
907 elt
= gimple_switch_label (stmt
, 1);
908 minval
= fold_convert (index_type
, CASE_LOW (elt
));
909 elt
= gimple_switch_label (stmt
, ncases
- 1);
911 maxval
= fold_convert (index_type
, CASE_HIGH (elt
));
913 maxval
= fold_convert (index_type
, CASE_LOW (elt
));
915 /* Compute span of values. */
916 range
= fold_build2 (MINUS_EXPR
, index_type
, maxval
, minval
);
918 /* Listify the labels queue and gather some numbers to decide
919 how to expand this switch(). */
922 for (i
= ncases
- 1; i
>= 1; --i
)
924 elt
= gimple_switch_label (stmt
, i
);
925 tree low
= CASE_LOW (elt
);
927 tree high
= CASE_HIGH (elt
);
928 gcc_assert (! high
|| tree_int_cst_lt (low
, high
));
929 tree lab
= CASE_LABEL (elt
);
931 /* Count the elements.
932 A range counts double, since it requires two compares. */
937 /* The bounds on the case range, LOW and HIGH, have to be converted
938 to case's index type TYPE. Note that the original type of the
939 case index in the source code is usually "lost" during
940 gimplification due to type promotion, but the case labels retain the
941 original type. Make sure to drop overflow flags. */
942 low
= fold_convert (index_type
, low
);
943 if (TREE_OVERFLOW (low
))
944 low
= wide_int_to_tree (index_type
, wi::to_wide (low
));
946 /* The canonical from of a case label in GIMPLE is that a simple case
947 has an empty CASE_HIGH. For the casesi and tablejump expanders,
948 the back ends want simple cases to have high == low. */
951 high
= fold_convert (index_type
, high
);
952 if (TREE_OVERFLOW (high
))
953 high
= wide_int_to_tree (index_type
, wi::to_wide (high
));
955 case_list
.safe_push (simple_case_node (low
, high
, lab
));
958 /* cleanup_tree_cfg removes all SWITCH_EXPR with a single
959 destination, such as one with a default case only.
960 It also removes cases that are out of range for the switch
961 type, so we should never get a zero here. */
962 gcc_assert (count
> 0);
964 rtx_insn
*before_case
= get_last_insn ();
966 /* Decide how to expand this switch.
967 The two options at this point are a dispatch table (casesi or
968 tablejump) or a decision tree. */
971 /* If the default case is unreachable, then set default_label to NULL
972 so that we omit the range check when generating the dispatch table.
973 We also remove the edge to the unreachable default case. The block
974 itself will be automatically removed later. */
975 if (EDGE_COUNT (default_edge
->dest
->succs
) == 0
976 && gimple_seq_unreachable_p (bb_seq (default_edge
->dest
)))
978 default_label
= NULL
;
979 remove_edge (default_edge
);
982 emit_case_dispatch_table (index_expr
, index_type
,
983 case_list
, default_label
, default_edge
,
984 minval
, maxval
, range
, bb
);
987 reorder_insns (NEXT_INSN (before_case
), get_last_insn (), before_case
);
992 /* Expand the dispatch to a short decrement chain if there are few cases
993 to dispatch to. Likewise if neither casesi nor tablejump is available,
994 or if flag_jump_tables is set. Otherwise, expand as a casesi or a
995 tablejump. The index mode is always the mode of integer_type_node.
996 Trap if no case matches the index.
998 DISPATCH_INDEX is the index expression to switch on. It should be a
999 memory or register operand.
1001 DISPATCH_TABLE is a set of case labels. The set should be sorted in
1002 ascending order, be contiguous, starting with value 0, and contain only
1003 single-valued case labels. */
1006 expand_sjlj_dispatch_table (rtx dispatch_index
,
1007 vec
<tree
> dispatch_table
)
1009 tree index_type
= integer_type_node
;
1010 machine_mode index_mode
= TYPE_MODE (index_type
);
1012 int ncases
= dispatch_table
.length ();
1014 do_pending_stack_adjust ();
1015 rtx_insn
*before_case
= get_last_insn ();
1017 /* Expand as a decrement-chain if there are 5 or fewer dispatch
1018 labels. This covers more than 98% of the cases in libjava,
1019 and seems to be a reasonable compromise between the "old way"
1020 of expanding as a decision tree or dispatch table vs. the "new
1021 way" with decrement chain or dispatch table. */
1022 if (dispatch_table
.length () <= 5
1023 || (!targetm
.have_casesi () && !targetm
.have_tablejump ())
1024 || !flag_jump_tables
)
1026 /* Expand the dispatch as a decrement chain:
1028 "switch(index) {case 0: do_0; case 1: do_1; ...; case N: do_N;}"
1032 if (index == 0) do_0; else index--;
1033 if (index == 0) do_1; else index--;
1035 if (index == 0) do_N; else index--;
1037 This is more efficient than a dispatch table on most machines.
1038 The last "index--" is redundant but the code is trivially dead
1039 and will be cleaned up by later passes. */
1040 rtx index
= copy_to_mode_reg (index_mode
, dispatch_index
);
1041 rtx zero
= CONST0_RTX (index_mode
);
1042 for (int i
= 0; i
< ncases
; i
++)
1044 tree elt
= dispatch_table
[i
];
1045 rtx_code_label
*lab
= jump_target_rtx (CASE_LABEL (elt
));
1046 do_jump_if_equal (index_mode
, index
, zero
, lab
, 0,
1047 profile_probability::uninitialized ());
1048 force_expand_binop (index_mode
, sub_optab
,
1049 index
, CONST1_RTX (index_mode
),
1050 index
, 0, OPTAB_DIRECT
);
1055 /* Similar to expand_case, but much simpler. */
1056 auto_vec
<simple_case_node
> case_list
;
1057 tree index_expr
= make_tree (index_type
, dispatch_index
);
1058 tree minval
= build_int_cst (index_type
, 0);
1059 tree maxval
= CASE_LOW (dispatch_table
.last ());
1060 tree range
= maxval
;
1061 rtx_code_label
*default_label
= gen_label_rtx ();
1063 for (int i
= ncases
- 1; i
>= 0; --i
)
1065 tree elt
= dispatch_table
[i
];
1066 tree high
= CASE_HIGH (elt
);
1067 if (high
== NULL_TREE
)
1068 high
= CASE_LOW (elt
);
1069 case_list
.safe_push (simple_case_node (CASE_LOW (elt
), high
,
1073 emit_case_dispatch_table (index_expr
, index_type
,
1074 case_list
, default_label
, NULL
,
1075 minval
, maxval
, range
,
1076 BLOCK_FOR_INSN (before_case
));
1077 emit_label (default_label
);
1080 /* Dispatching something not handled? Trap! */
1081 expand_builtin_trap ();
1083 reorder_insns (NEXT_INSN (before_case
), get_last_insn (), before_case
);