- Test m_pkthdr.fw_flags against DUMMYNET_MBUF_TAGGED before trying to locate
[dragonfly/netmp.git] / contrib / gcc-4.1 / gcc / stmt.c
blob7eb77d20f60dad1fe9ba9204c3fc52a7ad00e4d5
1 /* Expands front end tree to back end RTL for GCC
2 Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997,
3 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
21 02110-1301, USA. */
23 /* This file handles the generation of rtl code from tree structure
24 above the level of expressions, using subroutines in exp*.c and emit-rtl.c.
25 The functions whose names start with `expand_' are called by the
26 expander to generate RTL instructions for various kinds of constructs. */
28 #include "config.h"
29 #include "system.h"
30 #include "coretypes.h"
31 #include "tm.h"
33 #include "rtl.h"
34 #include "hard-reg-set.h"
35 #include "tree.h"
36 #include "tm_p.h"
37 #include "flags.h"
38 #include "except.h"
39 #include "function.h"
40 #include "insn-config.h"
41 #include "expr.h"
42 #include "libfuncs.h"
43 #include "recog.h"
44 #include "machmode.h"
45 #include "toplev.h"
46 #include "output.h"
47 #include "ggc.h"
48 #include "langhooks.h"
49 #include "predict.h"
50 #include "optabs.h"
51 #include "target.h"
52 #include "regs.h"
54 /* Functions and data structures for expanding case statements. */
56 /* Case label structure, used to hold info on labels within case
57 statements. We handle "range" labels; for a single-value label
58 as in C, the high and low limits are the same.
60 We start with a vector of case nodes sorted in ascending order, and
61 the default label as the last element in the vector. Before expanding
62 to RTL, we transform this vector into a list linked via the RIGHT
63 fields in the case_node struct. Nodes with higher case values are
64 later in the list.
66 Switch statements can be output in three forms. A branch table is
67 used if there are more than a few labels and the labels are dense
68 within the range between the smallest and largest case value. If a
69 branch table is used, no further manipulations are done with the case
70 node chain.
72 The alternative to the use of a branch table is to generate a series
73 of compare and jump insns. When that is done, we use the LEFT, RIGHT,
74 and PARENT fields to hold a binary tree. Initially the tree is
75 totally unbalanced, with everything on the right. We balance the tree
76 with nodes on the left having lower case values than the parent
77 and nodes on the right having higher values. We then output the tree
78 in order.
80 For very small, suitable switch statements, we can generate a series
81 of simple bit test and branches instead. */
83 struct case_node GTY(())
85 struct case_node *left; /* Left son in binary tree */
86 struct case_node *right; /* Right son in binary tree; also node chain */
87 struct case_node *parent; /* Parent of node in binary tree */
88 tree low; /* Lowest index value for this label */
89 tree high; /* Highest index value for this label */
90 tree code_label; /* Label to jump to when node matches */
93 typedef struct case_node case_node;
94 typedef struct case_node *case_node_ptr;
96 /* These are used by estimate_case_costs and balance_case_nodes. */
98 /* This must be a signed type, and non-ANSI compilers lack signed char. */
99 static short cost_table_[129];
100 static int use_cost_table;
101 static int cost_table_initialized;
103 /* Special care is needed because we allow -1, but TREE_INT_CST_LOW
104 is unsigned. */
105 #define COST_TABLE(I) cost_table_[(unsigned HOST_WIDE_INT) ((I) + 1)]
107 static int n_occurrences (int, const char *);
108 static bool tree_conflicts_with_clobbers_p (tree, HARD_REG_SET *);
109 static void expand_nl_goto_receiver (void);
110 static bool check_operand_nalternatives (tree, tree);
111 static bool check_unique_operand_names (tree, tree);
112 static char *resolve_operand_name_1 (char *, tree, tree);
113 static void expand_null_return_1 (void);
114 static void expand_value_return (rtx);
115 static void do_jump_if_equal (rtx, rtx, rtx, int);
116 static int estimate_case_costs (case_node_ptr);
117 static bool lshift_cheap_p (void);
118 static int case_bit_test_cmp (const void *, const void *);
119 static void emit_case_bit_tests (tree, tree, tree, tree, case_node_ptr, rtx);
120 static void balance_case_nodes (case_node_ptr *, case_node_ptr);
121 static int node_has_low_bound (case_node_ptr, tree);
122 static int node_has_high_bound (case_node_ptr, tree);
123 static int node_is_bounded (case_node_ptr, tree);
124 static void emit_case_nodes (rtx, case_node_ptr, rtx, tree);
125 static struct case_node *add_case_node (struct case_node *, tree,
126 tree, tree, tree);
129 /* Return the rtx-label that corresponds to a LABEL_DECL,
130 creating it if necessary. */
133 label_rtx (tree label)
135 gcc_assert (TREE_CODE (label) == LABEL_DECL);
137 if (!DECL_RTL_SET_P (label))
139 rtx r = gen_label_rtx ();
140 SET_DECL_RTL (label, r);
141 if (FORCED_LABEL (label) || DECL_NONLOCAL (label))
142 LABEL_PRESERVE_P (r) = 1;
145 return DECL_RTL (label);
148 /* As above, but also put it on the forced-reference list of the
149 function that contains it. */
151 force_label_rtx (tree label)
153 rtx ref = label_rtx (label);
154 tree function = decl_function_context (label);
155 struct function *p;
157 gcc_assert (function);
159 if (function != current_function_decl)
160 p = find_function_data (function);
161 else
162 p = cfun;
164 p->expr->x_forced_labels = gen_rtx_EXPR_LIST (VOIDmode, ref,
165 p->expr->x_forced_labels);
166 return ref;
169 /* Add an unconditional jump to LABEL as the next sequential instruction. */
171 void
172 emit_jump (rtx label)
174 do_pending_stack_adjust ();
175 emit_jump_insn (gen_jump (label));
176 emit_barrier ();
179 /* Emit code to jump to the address
180 specified by the pointer expression EXP. */
182 void
183 expand_computed_goto (tree exp)
185 rtx x = expand_expr (exp, NULL_RTX, VOIDmode, 0);
187 x = convert_memory_address (Pmode, x);
189 do_pending_stack_adjust ();
190 emit_indirect_jump (x);
193 /* Handle goto statements and the labels that they can go to. */
195 /* Specify the location in the RTL code of a label LABEL,
196 which is a LABEL_DECL tree node.
198 This is used for the kind of label that the user can jump to with a
199 goto statement, and for alternatives of a switch or case statement.
200 RTL labels generated for loops and conditionals don't go through here;
201 they are generated directly at the RTL level, by other functions below.
203 Note that this has nothing to do with defining label *names*.
204 Languages vary in how they do that and what that even means. */
206 void
207 expand_label (tree label)
209 rtx label_r = label_rtx (label);
211 do_pending_stack_adjust ();
212 emit_label (label_r);
213 if (DECL_NAME (label))
214 LABEL_NAME (DECL_RTL (label)) = IDENTIFIER_POINTER (DECL_NAME (label));
216 if (DECL_NONLOCAL (label))
218 expand_nl_goto_receiver ();
219 nonlocal_goto_handler_labels
220 = gen_rtx_EXPR_LIST (VOIDmode, label_r,
221 nonlocal_goto_handler_labels);
224 if (FORCED_LABEL (label))
225 forced_labels = gen_rtx_EXPR_LIST (VOIDmode, label_r, forced_labels);
227 if (DECL_NONLOCAL (label) || FORCED_LABEL (label))
228 maybe_set_first_label_num (label_r);
231 /* Generate RTL code for a `goto' statement with target label LABEL.
232 LABEL should be a LABEL_DECL tree node that was or will later be
233 defined with `expand_label'. */
235 void
236 expand_goto (tree label)
238 #ifdef ENABLE_CHECKING
239 /* Check for a nonlocal goto to a containing function. Should have
240 gotten translated to __builtin_nonlocal_goto. */
241 tree context = decl_function_context (label);
242 gcc_assert (!context || context == current_function_decl);
243 #endif
245 emit_jump (label_rtx (label));
248 /* Return the number of times character C occurs in string S. */
249 static int
250 n_occurrences (int c, const char *s)
252 int n = 0;
253 while (*s)
254 n += (*s++ == c);
255 return n;
258 /* Generate RTL for an asm statement (explicit assembler code).
259 STRING is a STRING_CST node containing the assembler code text,
260 or an ADDR_EXPR containing a STRING_CST. VOL nonzero means the
261 insn is volatile; don't optimize it. */
263 static void
264 expand_asm (tree string, int vol)
266 rtx body;
268 if (TREE_CODE (string) == ADDR_EXPR)
269 string = TREE_OPERAND (string, 0);
271 body = gen_rtx_ASM_INPUT (VOIDmode,
272 ggc_strdup (TREE_STRING_POINTER (string)));
274 MEM_VOLATILE_P (body) = vol;
276 emit_insn (body);
279 /* Parse the output constraint pointed to by *CONSTRAINT_P. It is the
280 OPERAND_NUMth output operand, indexed from zero. There are NINPUTS
281 inputs and NOUTPUTS outputs to this extended-asm. Upon return,
282 *ALLOWS_MEM will be TRUE iff the constraint allows the use of a
283 memory operand. Similarly, *ALLOWS_REG will be TRUE iff the
284 constraint allows the use of a register operand. And, *IS_INOUT
285 will be true if the operand is read-write, i.e., if it is used as
286 an input as well as an output. If *CONSTRAINT_P is not in
287 canonical form, it will be made canonical. (Note that `+' will be
288 replaced with `=' as part of this process.)
290 Returns TRUE if all went well; FALSE if an error occurred. */
292 bool
293 parse_output_constraint (const char **constraint_p, int operand_num,
294 int ninputs, int noutputs, bool *allows_mem,
295 bool *allows_reg, bool *is_inout)
297 const char *constraint = *constraint_p;
298 const char *p;
300 /* Assume the constraint doesn't allow the use of either a register
301 or memory. */
302 *allows_mem = false;
303 *allows_reg = false;
305 /* Allow the `=' or `+' to not be at the beginning of the string,
306 since it wasn't explicitly documented that way, and there is a
307 large body of code that puts it last. Swap the character to
308 the front, so as not to uglify any place else. */
309 p = strchr (constraint, '=');
310 if (!p)
311 p = strchr (constraint, '+');
313 /* If the string doesn't contain an `=', issue an error
314 message. */
315 if (!p)
317 error ("output operand constraint lacks %<=%>");
318 return false;
321 /* If the constraint begins with `+', then the operand is both read
322 from and written to. */
323 *is_inout = (*p == '+');
325 /* Canonicalize the output constraint so that it begins with `='. */
326 if (p != constraint || *is_inout)
328 char *buf;
329 size_t c_len = strlen (constraint);
331 if (p != constraint)
332 warning (0, "output constraint %qc for operand %d "
333 "is not at the beginning",
334 *p, operand_num);
336 /* Make a copy of the constraint. */
337 buf = alloca (c_len + 1);
338 strcpy (buf, constraint);
339 /* Swap the first character and the `=' or `+'. */
340 buf[p - constraint] = buf[0];
341 /* Make sure the first character is an `='. (Until we do this,
342 it might be a `+'.) */
343 buf[0] = '=';
344 /* Replace the constraint with the canonicalized string. */
345 *constraint_p = ggc_alloc_string (buf, c_len);
346 constraint = *constraint_p;
349 /* Loop through the constraint string. */
350 for (p = constraint + 1; *p; p += CONSTRAINT_LEN (*p, p))
351 switch (*p)
353 case '+':
354 case '=':
355 error ("operand constraint contains incorrectly positioned "
356 "%<+%> or %<=%>");
357 return false;
359 case '%':
360 if (operand_num + 1 == ninputs + noutputs)
362 error ("%<%%%> constraint used with last operand");
363 return false;
365 break;
367 case 'V': case 'm': case 'o':
368 *allows_mem = true;
369 break;
371 case '?': case '!': case '*': case '&': case '#':
372 case 'E': case 'F': case 'G': case 'H':
373 case 's': case 'i': case 'n':
374 case 'I': case 'J': case 'K': case 'L': case 'M':
375 case 'N': case 'O': case 'P': case ',':
376 break;
378 case '0': case '1': case '2': case '3': case '4':
379 case '5': case '6': case '7': case '8': case '9':
380 case '[':
381 error ("matching constraint not valid in output operand");
382 return false;
384 case '<': case '>':
385 /* ??? Before flow, auto inc/dec insns are not supposed to exist,
386 excepting those that expand_call created. So match memory
387 and hope. */
388 *allows_mem = true;
389 break;
391 case 'g': case 'X':
392 *allows_reg = true;
393 *allows_mem = true;
394 break;
396 case 'p': case 'r':
397 *allows_reg = true;
398 break;
400 default:
401 if (!ISALPHA (*p))
402 break;
403 if (REG_CLASS_FROM_CONSTRAINT (*p, p) != NO_REGS)
404 *allows_reg = true;
405 #ifdef EXTRA_CONSTRAINT_STR
406 else if (EXTRA_ADDRESS_CONSTRAINT (*p, p))
407 *allows_reg = true;
408 else if (EXTRA_MEMORY_CONSTRAINT (*p, p))
409 *allows_mem = true;
410 else
412 /* Otherwise we can't assume anything about the nature of
413 the constraint except that it isn't purely registers.
414 Treat it like "g" and hope for the best. */
415 *allows_reg = true;
416 *allows_mem = true;
418 #endif
419 break;
422 return true;
425 /* Similar, but for input constraints. */
427 bool
428 parse_input_constraint (const char **constraint_p, int input_num,
429 int ninputs, int noutputs, int ninout,
430 const char * const * constraints,
431 bool *allows_mem, bool *allows_reg)
433 const char *constraint = *constraint_p;
434 const char *orig_constraint = constraint;
435 size_t c_len = strlen (constraint);
436 size_t j;
437 bool saw_match = false;
439 /* Assume the constraint doesn't allow the use of either
440 a register or memory. */
441 *allows_mem = false;
442 *allows_reg = false;
444 /* Make sure constraint has neither `=', `+', nor '&'. */
446 for (j = 0; j < c_len; j += CONSTRAINT_LEN (constraint[j], constraint+j))
447 switch (constraint[j])
449 case '+': case '=': case '&':
450 if (constraint == orig_constraint)
452 error ("input operand constraint contains %qc", constraint[j]);
453 return false;
455 break;
457 case '%':
458 if (constraint == orig_constraint
459 && input_num + 1 == ninputs - ninout)
461 error ("%<%%%> constraint used with last operand");
462 return false;
464 break;
466 case 'V': case 'm': case 'o':
467 *allows_mem = true;
468 break;
470 case '<': case '>':
471 case '?': case '!': case '*': case '#':
472 case 'E': case 'F': case 'G': case 'H':
473 case 's': case 'i': case 'n':
474 case 'I': case 'J': case 'K': case 'L': case 'M':
475 case 'N': case 'O': case 'P': case ',':
476 break;
478 /* Whether or not a numeric constraint allows a register is
479 decided by the matching constraint, and so there is no need
480 to do anything special with them. We must handle them in
481 the default case, so that we don't unnecessarily force
482 operands to memory. */
483 case '0': case '1': case '2': case '3': case '4':
484 case '5': case '6': case '7': case '8': case '9':
486 char *end;
487 unsigned long match;
489 saw_match = true;
491 match = strtoul (constraint + j, &end, 10);
492 if (match >= (unsigned long) noutputs)
494 error ("matching constraint references invalid operand number");
495 return false;
498 /* Try and find the real constraint for this dup. Only do this
499 if the matching constraint is the only alternative. */
500 if (*end == '\0'
501 && (j == 0 || (j == 1 && constraint[0] == '%')))
503 constraint = constraints[match];
504 *constraint_p = constraint;
505 c_len = strlen (constraint);
506 j = 0;
507 /* ??? At the end of the loop, we will skip the first part of
508 the matched constraint. This assumes not only that the
509 other constraint is an output constraint, but also that
510 the '=' or '+' come first. */
511 break;
513 else
514 j = end - constraint;
515 /* Anticipate increment at end of loop. */
516 j--;
518 /* Fall through. */
520 case 'p': case 'r':
521 *allows_reg = true;
522 break;
524 case 'g': case 'X':
525 *allows_reg = true;
526 *allows_mem = true;
527 break;
529 default:
530 if (! ISALPHA (constraint[j]))
532 error ("invalid punctuation %qc in constraint", constraint[j]);
533 return false;
535 if (REG_CLASS_FROM_CONSTRAINT (constraint[j], constraint + j)
536 != NO_REGS)
537 *allows_reg = true;
538 #ifdef EXTRA_CONSTRAINT_STR
539 else if (EXTRA_ADDRESS_CONSTRAINT (constraint[j], constraint + j))
540 *allows_reg = true;
541 else if (EXTRA_MEMORY_CONSTRAINT (constraint[j], constraint + j))
542 *allows_mem = true;
543 else
545 /* Otherwise we can't assume anything about the nature of
546 the constraint except that it isn't purely registers.
547 Treat it like "g" and hope for the best. */
548 *allows_reg = true;
549 *allows_mem = true;
551 #endif
552 break;
555 if (saw_match && !*allows_reg)
556 warning (0, "matching constraint does not allow a register");
558 return true;
561 /* Return DECL iff there's an overlap between *REGS and DECL, where DECL
562 can be an asm-declared register. Called via walk_tree. */
564 static tree
565 decl_overlaps_hard_reg_set_p (tree *declp, int *walk_subtrees ATTRIBUTE_UNUSED,
566 void *data)
568 tree decl = *declp;
569 const HARD_REG_SET *regs = data;
571 if (TREE_CODE (decl) == VAR_DECL)
573 if (DECL_HARD_REGISTER (decl)
574 && REG_P (DECL_RTL (decl))
575 && REGNO (DECL_RTL (decl)) < FIRST_PSEUDO_REGISTER)
577 rtx reg = DECL_RTL (decl);
578 unsigned int regno;
580 for (regno = REGNO (reg);
581 regno < (REGNO (reg)
582 + hard_regno_nregs[REGNO (reg)][GET_MODE (reg)]);
583 regno++)
584 if (TEST_HARD_REG_BIT (*regs, regno))
585 return decl;
587 walk_subtrees = 0;
589 else if (TYPE_P (decl) || TREE_CODE (decl) == PARM_DECL)
590 walk_subtrees = 0;
591 return NULL_TREE;
594 /* If there is an overlap between *REGS and DECL, return the first overlap
595 found. */
596 tree
597 tree_overlaps_hard_reg_set (tree decl, HARD_REG_SET *regs)
599 return walk_tree (&decl, decl_overlaps_hard_reg_set_p, regs, NULL);
602 /* Check for overlap between registers marked in CLOBBERED_REGS and
603 anything inappropriate in T. Emit error and return the register
604 variable definition for error, NULL_TREE for ok. */
606 static bool
607 tree_conflicts_with_clobbers_p (tree t, HARD_REG_SET *clobbered_regs)
609 /* Conflicts between asm-declared register variables and the clobber
610 list are not allowed. */
611 tree overlap = tree_overlaps_hard_reg_set (t, clobbered_regs);
613 if (overlap)
615 error ("asm-specifier for variable %qs conflicts with asm clobber list",
616 IDENTIFIER_POINTER (DECL_NAME (overlap)));
618 /* Reset registerness to stop multiple errors emitted for a single
619 variable. */
620 DECL_REGISTER (overlap) = 0;
621 return true;
624 return false;
627 /* Generate RTL for an asm statement with arguments.
628 STRING is the instruction template.
629 OUTPUTS is a list of output arguments (lvalues); INPUTS a list of inputs.
630 Each output or input has an expression in the TREE_VALUE and
631 and a tree list in TREE_PURPOSE which in turn contains a constraint
632 name in TREE_VALUE (or NULL_TREE) and a constraint string
633 in TREE_PURPOSE.
634 CLOBBERS is a list of STRING_CST nodes each naming a hard register
635 that is clobbered by this insn.
637 Not all kinds of lvalue that may appear in OUTPUTS can be stored directly.
638 Some elements of OUTPUTS may be replaced with trees representing temporary
639 values. The caller should copy those temporary values to the originally
640 specified lvalues.
642 VOL nonzero means the insn is volatile; don't optimize it. */
644 static void
645 expand_asm_operands (tree string, tree outputs, tree inputs,
646 tree clobbers, int vol, location_t locus)
648 rtvec argvec, constraintvec;
649 rtx body;
650 int ninputs = list_length (inputs);
651 int noutputs = list_length (outputs);
652 int ninout;
653 int nclobbers;
654 HARD_REG_SET clobbered_regs;
655 int clobber_conflict_found = 0;
656 tree tail;
657 tree t;
658 int i;
659 /* Vector of RTX's of evaluated output operands. */
660 rtx *output_rtx = alloca (noutputs * sizeof (rtx));
661 int *inout_opnum = alloca (noutputs * sizeof (int));
662 rtx *real_output_rtx = alloca (noutputs * sizeof (rtx));
663 enum machine_mode *inout_mode
664 = alloca (noutputs * sizeof (enum machine_mode));
665 const char **constraints
666 = alloca ((noutputs + ninputs) * sizeof (const char *));
667 int old_generating_concat_p = generating_concat_p;
669 /* An ASM with no outputs needs to be treated as volatile, for now. */
670 if (noutputs == 0)
671 vol = 1;
673 if (! check_operand_nalternatives (outputs, inputs))
674 return;
676 string = resolve_asm_operand_names (string, outputs, inputs);
678 /* Collect constraints. */
679 i = 0;
680 for (t = outputs; t ; t = TREE_CHAIN (t), i++)
681 constraints[i] = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
682 for (t = inputs; t ; t = TREE_CHAIN (t), i++)
683 constraints[i] = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
685 /* Sometimes we wish to automatically clobber registers across an asm.
686 Case in point is when the i386 backend moved from cc0 to a hard reg --
687 maintaining source-level compatibility means automatically clobbering
688 the flags register. */
689 clobbers = targetm.md_asm_clobbers (outputs, inputs, clobbers);
691 /* Count the number of meaningful clobbered registers, ignoring what
692 we would ignore later. */
693 nclobbers = 0;
694 CLEAR_HARD_REG_SET (clobbered_regs);
695 for (tail = clobbers; tail; tail = TREE_CHAIN (tail))
697 const char *regname;
699 if (TREE_VALUE (tail) == error_mark_node)
700 return;
701 regname = TREE_STRING_POINTER (TREE_VALUE (tail));
703 i = decode_reg_name (regname);
704 if (i >= 0 || i == -4)
705 ++nclobbers;
706 else if (i == -2)
707 error ("unknown register name %qs in %<asm%>", regname);
709 /* Mark clobbered registers. */
710 if (i >= 0)
712 /* Clobbering the PIC register is an error. */
713 if (i == (int) PIC_OFFSET_TABLE_REGNUM)
715 error ("PIC register %qs clobbered in %<asm%>", regname);
716 return;
719 SET_HARD_REG_BIT (clobbered_regs, i);
723 /* First pass over inputs and outputs checks validity and sets
724 mark_addressable if needed. */
726 ninout = 0;
727 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
729 tree val = TREE_VALUE (tail);
730 tree type = TREE_TYPE (val);
731 const char *constraint;
732 bool is_inout;
733 bool allows_reg;
734 bool allows_mem;
736 /* If there's an erroneous arg, emit no insn. */
737 if (type == error_mark_node)
738 return;
740 /* Try to parse the output constraint. If that fails, there's
741 no point in going further. */
742 constraint = constraints[i];
743 if (!parse_output_constraint (&constraint, i, ninputs, noutputs,
744 &allows_mem, &allows_reg, &is_inout))
745 return;
747 if (! allows_reg
748 && (allows_mem
749 || is_inout
750 || (DECL_P (val)
751 && REG_P (DECL_RTL (val))
752 && GET_MODE (DECL_RTL (val)) != TYPE_MODE (type))))
753 lang_hooks.mark_addressable (val);
755 if (is_inout)
756 ninout++;
759 ninputs += ninout;
760 if (ninputs + noutputs > MAX_RECOG_OPERANDS)
762 error ("more than %d operands in %<asm%>", MAX_RECOG_OPERANDS);
763 return;
766 for (i = 0, tail = inputs; tail; i++, tail = TREE_CHAIN (tail))
768 bool allows_reg, allows_mem;
769 const char *constraint;
771 /* If there's an erroneous arg, emit no insn, because the ASM_INPUT
772 would get VOIDmode and that could cause a crash in reload. */
773 if (TREE_TYPE (TREE_VALUE (tail)) == error_mark_node)
774 return;
776 constraint = constraints[i + noutputs];
777 if (! parse_input_constraint (&constraint, i, ninputs, noutputs, ninout,
778 constraints, &allows_mem, &allows_reg))
779 return;
781 if (! allows_reg && allows_mem)
782 lang_hooks.mark_addressable (TREE_VALUE (tail));
785 /* Second pass evaluates arguments. */
787 ninout = 0;
788 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
790 tree val = TREE_VALUE (tail);
791 tree type = TREE_TYPE (val);
792 bool is_inout;
793 bool allows_reg;
794 bool allows_mem;
795 rtx op;
796 bool ok;
798 ok = parse_output_constraint (&constraints[i], i, ninputs,
799 noutputs, &allows_mem, &allows_reg,
800 &is_inout);
801 gcc_assert (ok);
803 /* If an output operand is not a decl or indirect ref and our constraint
804 allows a register, make a temporary to act as an intermediate.
805 Make the asm insn write into that, then our caller will copy it to
806 the real output operand. Likewise for promoted variables. */
808 generating_concat_p = 0;
810 real_output_rtx[i] = NULL_RTX;
811 if ((TREE_CODE (val) == INDIRECT_REF
812 && allows_mem)
813 || (DECL_P (val)
814 && (allows_mem || REG_P (DECL_RTL (val)))
815 && ! (REG_P (DECL_RTL (val))
816 && GET_MODE (DECL_RTL (val)) != TYPE_MODE (type)))
817 || ! allows_reg
818 || is_inout)
820 op = expand_expr (val, NULL_RTX, VOIDmode, EXPAND_WRITE);
821 if (MEM_P (op))
822 op = validize_mem (op);
824 if (! allows_reg && !MEM_P (op))
825 error ("output number %d not directly addressable", i);
826 if ((! allows_mem && MEM_P (op))
827 || GET_CODE (op) == CONCAT)
829 real_output_rtx[i] = op;
830 op = gen_reg_rtx (GET_MODE (op));
831 if (is_inout)
832 emit_move_insn (op, real_output_rtx[i]);
835 else
837 op = assign_temp (type, 0, 0, 1);
838 op = validize_mem (op);
839 TREE_VALUE (tail) = make_tree (type, op);
841 output_rtx[i] = op;
843 generating_concat_p = old_generating_concat_p;
845 if (is_inout)
847 inout_mode[ninout] = TYPE_MODE (type);
848 inout_opnum[ninout++] = i;
851 if (tree_conflicts_with_clobbers_p (val, &clobbered_regs))
852 clobber_conflict_found = 1;
855 /* Make vectors for the expression-rtx, constraint strings,
856 and named operands. */
858 argvec = rtvec_alloc (ninputs);
859 constraintvec = rtvec_alloc (ninputs);
861 body = gen_rtx_ASM_OPERANDS ((noutputs == 0 ? VOIDmode
862 : GET_MODE (output_rtx[0])),
863 ggc_strdup (TREE_STRING_POINTER (string)),
864 empty_string, 0, argvec, constraintvec,
865 locus);
867 MEM_VOLATILE_P (body) = vol;
869 /* Eval the inputs and put them into ARGVEC.
870 Put their constraints into ASM_INPUTs and store in CONSTRAINTS. */
872 for (i = 0, tail = inputs; tail; tail = TREE_CHAIN (tail), ++i)
874 bool allows_reg, allows_mem;
875 const char *constraint;
876 tree val, type;
877 rtx op;
878 bool ok;
880 constraint = constraints[i + noutputs];
881 ok = parse_input_constraint (&constraint, i, ninputs, noutputs, ninout,
882 constraints, &allows_mem, &allows_reg);
883 gcc_assert (ok);
885 generating_concat_p = 0;
887 val = TREE_VALUE (tail);
888 type = TREE_TYPE (val);
889 op = expand_expr (val, NULL_RTX, VOIDmode,
890 (allows_mem && !allows_reg
891 ? EXPAND_MEMORY : EXPAND_NORMAL));
893 /* Never pass a CONCAT to an ASM. */
894 if (GET_CODE (op) == CONCAT)
895 op = force_reg (GET_MODE (op), op);
896 else if (MEM_P (op))
897 op = validize_mem (op);
899 if (asm_operand_ok (op, constraint) <= 0)
901 if (allows_reg && TYPE_MODE (type) != BLKmode)
902 op = force_reg (TYPE_MODE (type), op);
903 else if (!allows_mem)
904 warning (0, "asm operand %d probably doesn%'t match constraints",
905 i + noutputs);
906 else if (MEM_P (op))
908 /* We won't recognize either volatile memory or memory
909 with a queued address as available a memory_operand
910 at this point. Ignore it: clearly this *is* a memory. */
912 else
914 warning (0, "use of memory input without lvalue in "
915 "asm operand %d is deprecated", i + noutputs);
917 if (CONSTANT_P (op))
919 rtx mem = force_const_mem (TYPE_MODE (type), op);
920 if (mem)
921 op = validize_mem (mem);
922 else
923 op = force_reg (TYPE_MODE (type), op);
925 if (REG_P (op)
926 || GET_CODE (op) == SUBREG
927 || GET_CODE (op) == CONCAT)
929 tree qual_type = build_qualified_type (type,
930 (TYPE_QUALS (type)
931 | TYPE_QUAL_CONST));
932 rtx memloc = assign_temp (qual_type, 1, 1, 1);
933 memloc = validize_mem (memloc);
934 emit_move_insn (memloc, op);
935 op = memloc;
940 generating_concat_p = old_generating_concat_p;
941 ASM_OPERANDS_INPUT (body, i) = op;
943 ASM_OPERANDS_INPUT_CONSTRAINT_EXP (body, i)
944 = gen_rtx_ASM_INPUT (TYPE_MODE (type),
945 ggc_strdup (constraints[i + noutputs]));
947 if (tree_conflicts_with_clobbers_p (val, &clobbered_regs))
948 clobber_conflict_found = 1;
951 /* Protect all the operands from the queue now that they have all been
952 evaluated. */
954 generating_concat_p = 0;
956 /* For in-out operands, copy output rtx to input rtx. */
957 for (i = 0; i < ninout; i++)
959 int j = inout_opnum[i];
960 char buffer[16];
962 ASM_OPERANDS_INPUT (body, ninputs - ninout + i)
963 = output_rtx[j];
965 sprintf (buffer, "%d", j);
966 ASM_OPERANDS_INPUT_CONSTRAINT_EXP (body, ninputs - ninout + i)
967 = gen_rtx_ASM_INPUT (inout_mode[i], ggc_strdup (buffer));
970 generating_concat_p = old_generating_concat_p;
972 /* Now, for each output, construct an rtx
973 (set OUTPUT (asm_operands INSN OUTPUTCONSTRAINT OUTPUTNUMBER
974 ARGVEC CONSTRAINTS OPNAMES))
975 If there is more than one, put them inside a PARALLEL. */
977 if (noutputs == 1 && nclobbers == 0)
979 ASM_OPERANDS_OUTPUT_CONSTRAINT (body) = ggc_strdup (constraints[0]);
980 emit_insn (gen_rtx_SET (VOIDmode, output_rtx[0], body));
983 else if (noutputs == 0 && nclobbers == 0)
985 /* No output operands: put in a raw ASM_OPERANDS rtx. */
986 emit_insn (body);
989 else
991 rtx obody = body;
992 int num = noutputs;
994 if (num == 0)
995 num = 1;
997 body = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (num + nclobbers));
999 /* For each output operand, store a SET. */
1000 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
1002 XVECEXP (body, 0, i)
1003 = gen_rtx_SET (VOIDmode,
1004 output_rtx[i],
1005 gen_rtx_ASM_OPERANDS
1006 (GET_MODE (output_rtx[i]),
1007 ggc_strdup (TREE_STRING_POINTER (string)),
1008 ggc_strdup (constraints[i]),
1009 i, argvec, constraintvec, locus));
1011 MEM_VOLATILE_P (SET_SRC (XVECEXP (body, 0, i))) = vol;
1014 /* If there are no outputs (but there are some clobbers)
1015 store the bare ASM_OPERANDS into the PARALLEL. */
1017 if (i == 0)
1018 XVECEXP (body, 0, i++) = obody;
1020 /* Store (clobber REG) for each clobbered register specified. */
1022 for (tail = clobbers; tail; tail = TREE_CHAIN (tail))
1024 const char *regname = TREE_STRING_POINTER (TREE_VALUE (tail));
1025 int j = decode_reg_name (regname);
1026 rtx clobbered_reg;
1028 if (j < 0)
1030 if (j == -3) /* `cc', which is not a register */
1031 continue;
1033 if (j == -4) /* `memory', don't cache memory across asm */
1035 XVECEXP (body, 0, i++)
1036 = gen_rtx_CLOBBER (VOIDmode,
1037 gen_rtx_MEM
1038 (BLKmode,
1039 gen_rtx_SCRATCH (VOIDmode)));
1040 continue;
1043 /* Ignore unknown register, error already signaled. */
1044 continue;
1047 /* Use QImode since that's guaranteed to clobber just one reg. */
1048 clobbered_reg = gen_rtx_REG (QImode, j);
1050 /* Do sanity check for overlap between clobbers and respectively
1051 input and outputs that hasn't been handled. Such overlap
1052 should have been detected and reported above. */
1053 if (!clobber_conflict_found)
1055 int opno;
1057 /* We test the old body (obody) contents to avoid tripping
1058 over the under-construction body. */
1059 for (opno = 0; opno < noutputs; opno++)
1060 if (reg_overlap_mentioned_p (clobbered_reg, output_rtx[opno]))
1061 internal_error ("asm clobber conflict with output operand");
1063 for (opno = 0; opno < ninputs - ninout; opno++)
1064 if (reg_overlap_mentioned_p (clobbered_reg,
1065 ASM_OPERANDS_INPUT (obody, opno)))
1066 internal_error ("asm clobber conflict with input operand");
1069 XVECEXP (body, 0, i++)
1070 = gen_rtx_CLOBBER (VOIDmode, clobbered_reg);
1073 emit_insn (body);
1076 /* For any outputs that needed reloading into registers, spill them
1077 back to where they belong. */
1078 for (i = 0; i < noutputs; ++i)
1079 if (real_output_rtx[i])
1080 emit_move_insn (real_output_rtx[i], output_rtx[i]);
1082 free_temp_slots ();
1085 void
1086 expand_asm_expr (tree exp)
1088 int noutputs, i;
1089 tree outputs, tail;
1090 tree *o;
1092 if (ASM_INPUT_P (exp))
1094 expand_asm (ASM_STRING (exp), ASM_VOLATILE_P (exp));
1095 return;
1098 outputs = ASM_OUTPUTS (exp);
1099 noutputs = list_length (outputs);
1100 /* o[I] is the place that output number I should be written. */
1101 o = (tree *) alloca (noutputs * sizeof (tree));
1103 /* Record the contents of OUTPUTS before it is modified. */
1104 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
1105 o[i] = TREE_VALUE (tail);
1107 /* Generate the ASM_OPERANDS insn; store into the TREE_VALUEs of
1108 OUTPUTS some trees for where the values were actually stored. */
1109 expand_asm_operands (ASM_STRING (exp), outputs, ASM_INPUTS (exp),
1110 ASM_CLOBBERS (exp), ASM_VOLATILE_P (exp),
1111 input_location);
1113 /* Copy all the intermediate outputs into the specified outputs. */
1114 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
1116 if (o[i] != TREE_VALUE (tail))
1118 expand_assignment (o[i], TREE_VALUE (tail));
1119 free_temp_slots ();
1121 /* Restore the original value so that it's correct the next
1122 time we expand this function. */
1123 TREE_VALUE (tail) = o[i];
1128 /* A subroutine of expand_asm_operands. Check that all operands have
1129 the same number of alternatives. Return true if so. */
1131 static bool
1132 check_operand_nalternatives (tree outputs, tree inputs)
1134 if (outputs || inputs)
1136 tree tmp = TREE_PURPOSE (outputs ? outputs : inputs);
1137 int nalternatives
1138 = n_occurrences (',', TREE_STRING_POINTER (TREE_VALUE (tmp)));
1139 tree next = inputs;
1141 if (nalternatives + 1 > MAX_RECOG_ALTERNATIVES)
1143 error ("too many alternatives in %<asm%>");
1144 return false;
1147 tmp = outputs;
1148 while (tmp)
1150 const char *constraint
1151 = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tmp)));
1153 if (n_occurrences (',', constraint) != nalternatives)
1155 error ("operand constraints for %<asm%> differ "
1156 "in number of alternatives");
1157 return false;
1160 if (TREE_CHAIN (tmp))
1161 tmp = TREE_CHAIN (tmp);
1162 else
1163 tmp = next, next = 0;
1167 return true;
1170 /* A subroutine of expand_asm_operands. Check that all operand names
1171 are unique. Return true if so. We rely on the fact that these names
1172 are identifiers, and so have been canonicalized by get_identifier,
1173 so all we need are pointer comparisons. */
1175 static bool
1176 check_unique_operand_names (tree outputs, tree inputs)
1178 tree i, j;
1180 for (i = outputs; i ; i = TREE_CHAIN (i))
1182 tree i_name = TREE_PURPOSE (TREE_PURPOSE (i));
1183 if (! i_name)
1184 continue;
1186 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
1187 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
1188 goto failure;
1191 for (i = inputs; i ; i = TREE_CHAIN (i))
1193 tree i_name = TREE_PURPOSE (TREE_PURPOSE (i));
1194 if (! i_name)
1195 continue;
1197 for (j = TREE_CHAIN (i); j ; j = TREE_CHAIN (j))
1198 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
1199 goto failure;
1200 for (j = outputs; j ; j = TREE_CHAIN (j))
1201 if (simple_cst_equal (i_name, TREE_PURPOSE (TREE_PURPOSE (j))))
1202 goto failure;
1205 return true;
1207 failure:
1208 error ("duplicate asm operand name %qs",
1209 TREE_STRING_POINTER (TREE_PURPOSE (TREE_PURPOSE (i))));
1210 return false;
1213 /* A subroutine of expand_asm_operands. Resolve the names of the operands
1214 in *POUTPUTS and *PINPUTS to numbers, and replace the name expansions in
1215 STRING and in the constraints to those numbers. */
1217 tree
1218 resolve_asm_operand_names (tree string, tree outputs, tree inputs)
1220 char *buffer;
1221 char *p;
1222 const char *c;
1223 tree t;
1225 check_unique_operand_names (outputs, inputs);
1227 /* Substitute [<name>] in input constraint strings. There should be no
1228 named operands in output constraints. */
1229 for (t = inputs; t ; t = TREE_CHAIN (t))
1231 c = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
1232 if (strchr (c, '[') != NULL)
1234 p = buffer = xstrdup (c);
1235 while ((p = strchr (p, '[')) != NULL)
1236 p = resolve_operand_name_1 (p, outputs, inputs);
1237 TREE_VALUE (TREE_PURPOSE (t))
1238 = build_string (strlen (buffer), buffer);
1239 free (buffer);
1243 /* Now check for any needed substitutions in the template. */
1244 c = TREE_STRING_POINTER (string);
1245 while ((c = strchr (c, '%')) != NULL)
1247 if (c[1] == '[')
1248 break;
1249 else if (ISALPHA (c[1]) && c[2] == '[')
1250 break;
1251 else
1253 c += 1;
1254 continue;
1258 if (c)
1260 /* OK, we need to make a copy so we can perform the substitutions.
1261 Assume that we will not need extra space--we get to remove '['
1262 and ']', which means we cannot have a problem until we have more
1263 than 999 operands. */
1264 buffer = xstrdup (TREE_STRING_POINTER (string));
1265 p = buffer + (c - TREE_STRING_POINTER (string));
1267 while ((p = strchr (p, '%')) != NULL)
1269 if (p[1] == '[')
1270 p += 1;
1271 else if (ISALPHA (p[1]) && p[2] == '[')
1272 p += 2;
1273 else
1275 p += 1;
1276 continue;
1279 p = resolve_operand_name_1 (p, outputs, inputs);
1282 string = build_string (strlen (buffer), buffer);
1283 free (buffer);
1286 return string;
1289 /* A subroutine of resolve_operand_names. P points to the '[' for a
1290 potential named operand of the form [<name>]. In place, replace
1291 the name and brackets with a number. Return a pointer to the
1292 balance of the string after substitution. */
1294 static char *
1295 resolve_operand_name_1 (char *p, tree outputs, tree inputs)
1297 char *q;
1298 int op;
1299 tree t;
1300 size_t len;
1302 /* Collect the operand name. */
1303 q = strchr (p, ']');
1304 if (!q)
1306 error ("missing close brace for named operand");
1307 return strchr (p, '\0');
1309 len = q - p - 1;
1311 /* Resolve the name to a number. */
1312 for (op = 0, t = outputs; t ; t = TREE_CHAIN (t), op++)
1314 tree name = TREE_PURPOSE (TREE_PURPOSE (t));
1315 if (name)
1317 const char *c = TREE_STRING_POINTER (name);
1318 if (strncmp (c, p + 1, len) == 0 && c[len] == '\0')
1319 goto found;
1322 for (t = inputs; t ; t = TREE_CHAIN (t), op++)
1324 tree name = TREE_PURPOSE (TREE_PURPOSE (t));
1325 if (name)
1327 const char *c = TREE_STRING_POINTER (name);
1328 if (strncmp (c, p + 1, len) == 0 && c[len] == '\0')
1329 goto found;
1333 *q = '\0';
1334 error ("undefined named operand %qs", p + 1);
1335 op = 0;
1336 found:
1338 /* Replace the name with the number. Unfortunately, not all libraries
1339 get the return value of sprintf correct, so search for the end of the
1340 generated string by hand. */
1341 sprintf (p, "%d", op);
1342 p = strchr (p, '\0');
1344 /* Verify the no extra buffer space assumption. */
1345 gcc_assert (p <= q);
1347 /* Shift the rest of the buffer down to fill the gap. */
1348 memmove (p, q + 1, strlen (q + 1) + 1);
1350 return p;
1353 /* Generate RTL to evaluate the expression EXP. */
1355 void
1356 expand_expr_stmt (tree exp)
1358 rtx value;
1359 tree type;
1361 value = expand_expr (exp, const0_rtx, VOIDmode, 0);
1362 type = TREE_TYPE (exp);
1364 /* If all we do is reference a volatile value in memory,
1365 copy it to a register to be sure it is actually touched. */
1366 if (value && MEM_P (value) && TREE_THIS_VOLATILE (exp))
1368 if (TYPE_MODE (type) == VOIDmode)
1370 else if (TYPE_MODE (type) != BLKmode)
1371 value = copy_to_reg (value);
1372 else
1374 rtx lab = gen_label_rtx ();
1376 /* Compare the value with itself to reference it. */
1377 emit_cmp_and_jump_insns (value, value, EQ,
1378 expand_expr (TYPE_SIZE (type),
1379 NULL_RTX, VOIDmode, 0),
1380 BLKmode, 0, lab);
1381 emit_label (lab);
1385 /* Free any temporaries used to evaluate this expression. */
1386 free_temp_slots ();
1389 /* Warn if EXP contains any computations whose results are not used.
1390 Return 1 if a warning is printed; 0 otherwise. LOCUS is the
1391 (potential) location of the expression. */
1394 warn_if_unused_value (tree exp, location_t locus)
1396 restart:
1397 if (TREE_USED (exp) || TREE_NO_WARNING (exp))
1398 return 0;
1400 /* Don't warn about void constructs. This includes casting to void,
1401 void function calls, and statement expressions with a final cast
1402 to void. */
1403 if (VOID_TYPE_P (TREE_TYPE (exp)))
1404 return 0;
1406 if (EXPR_HAS_LOCATION (exp))
1407 locus = EXPR_LOCATION (exp);
1409 switch (TREE_CODE (exp))
1411 case PREINCREMENT_EXPR:
1412 case POSTINCREMENT_EXPR:
1413 case PREDECREMENT_EXPR:
1414 case POSTDECREMENT_EXPR:
1415 case MODIFY_EXPR:
1416 case INIT_EXPR:
1417 case TARGET_EXPR:
1418 case CALL_EXPR:
1419 case TRY_CATCH_EXPR:
1420 case WITH_CLEANUP_EXPR:
1421 case EXIT_EXPR:
1422 return 0;
1424 case BIND_EXPR:
1425 /* For a binding, warn if no side effect within it. */
1426 exp = BIND_EXPR_BODY (exp);
1427 goto restart;
1429 case SAVE_EXPR:
1430 exp = TREE_OPERAND (exp, 0);
1431 goto restart;
1433 case TRUTH_ORIF_EXPR:
1434 case TRUTH_ANDIF_EXPR:
1435 /* In && or ||, warn if 2nd operand has no side effect. */
1436 exp = TREE_OPERAND (exp, 1);
1437 goto restart;
1439 case COMPOUND_EXPR:
1440 if (warn_if_unused_value (TREE_OPERAND (exp, 0), locus))
1441 return 1;
1442 /* Let people do `(foo (), 0)' without a warning. */
1443 if (TREE_CONSTANT (TREE_OPERAND (exp, 1)))
1444 return 0;
1445 exp = TREE_OPERAND (exp, 1);
1446 goto restart;
1448 case COND_EXPR:
1449 /* If this is an expression with side effects, don't warn; this
1450 case commonly appears in macro expansions. */
1451 if (TREE_SIDE_EFFECTS (exp))
1452 return 0;
1453 goto warn;
1455 case INDIRECT_REF:
1456 /* Don't warn about automatic dereferencing of references, since
1457 the user cannot control it. */
1458 if (TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == REFERENCE_TYPE)
1460 exp = TREE_OPERAND (exp, 0);
1461 goto restart;
1463 /* Fall through. */
1465 default:
1466 /* Referencing a volatile value is a side effect, so don't warn. */
1467 if ((DECL_P (exp) || REFERENCE_CLASS_P (exp))
1468 && TREE_THIS_VOLATILE (exp))
1469 return 0;
1471 /* If this is an expression which has no operands, there is no value
1472 to be unused. There are no such language-independent codes,
1473 but front ends may define such. */
1474 if (EXPRESSION_CLASS_P (exp) && TREE_CODE_LENGTH (TREE_CODE (exp)) == 0)
1475 return 0;
1477 warn:
1478 warning (0, "%Hvalue computed is not used", &locus);
1479 return 1;
1484 /* Generate RTL to return from the current function, with no value.
1485 (That is, we do not do anything about returning any value.) */
1487 void
1488 expand_null_return (void)
1490 /* If this function was declared to return a value, but we
1491 didn't, clobber the return registers so that they are not
1492 propagated live to the rest of the function. */
1493 clobber_return_register ();
1495 expand_null_return_1 ();
1498 /* Generate RTL to return directly from the current function.
1499 (That is, we bypass any return value.) */
1501 void
1502 expand_naked_return (void)
1504 rtx end_label;
1506 clear_pending_stack_adjust ();
1507 do_pending_stack_adjust ();
1509 end_label = naked_return_label;
1510 if (end_label == 0)
1511 end_label = naked_return_label = gen_label_rtx ();
1513 emit_jump (end_label);
1516 /* Generate RTL to return from the current function, with value VAL. */
1518 static void
1519 expand_value_return (rtx val)
1521 /* Copy the value to the return location
1522 unless it's already there. */
1524 rtx return_reg = DECL_RTL (DECL_RESULT (current_function_decl));
1525 if (return_reg != val)
1527 tree type = TREE_TYPE (DECL_RESULT (current_function_decl));
1528 if (targetm.calls.promote_function_return (TREE_TYPE (current_function_decl)))
1530 int unsignedp = TYPE_UNSIGNED (type);
1531 enum machine_mode old_mode
1532 = DECL_MODE (DECL_RESULT (current_function_decl));
1533 enum machine_mode mode
1534 = promote_mode (type, old_mode, &unsignedp, 1);
1536 if (mode != old_mode)
1537 val = convert_modes (mode, old_mode, val, unsignedp);
1539 if (GET_CODE (return_reg) == PARALLEL)
1540 emit_group_load (return_reg, val, type, int_size_in_bytes (type));
1541 else
1542 emit_move_insn (return_reg, val);
1545 expand_null_return_1 ();
1548 /* Output a return with no value. */
1550 static void
1551 expand_null_return_1 (void)
1553 clear_pending_stack_adjust ();
1554 do_pending_stack_adjust ();
1555 emit_jump (return_label);
1558 /* Generate RTL to evaluate the expression RETVAL and return it
1559 from the current function. */
1561 void
1562 expand_return (tree retval)
1564 rtx result_rtl;
1565 rtx val = 0;
1566 tree retval_rhs;
1568 /* If function wants no value, give it none. */
1569 if (TREE_CODE (TREE_TYPE (TREE_TYPE (current_function_decl))) == VOID_TYPE)
1571 expand_expr (retval, NULL_RTX, VOIDmode, 0);
1572 expand_null_return ();
1573 return;
1576 if (retval == error_mark_node)
1578 /* Treat this like a return of no value from a function that
1579 returns a value. */
1580 expand_null_return ();
1581 return;
1583 else if ((TREE_CODE (retval) == MODIFY_EXPR
1584 || TREE_CODE (retval) == INIT_EXPR)
1585 && TREE_CODE (TREE_OPERAND (retval, 0)) == RESULT_DECL)
1586 retval_rhs = TREE_OPERAND (retval, 1);
1587 else
1588 retval_rhs = retval;
1590 result_rtl = DECL_RTL (DECL_RESULT (current_function_decl));
1592 /* If we are returning the RESULT_DECL, then the value has already
1593 been stored into it, so we don't have to do anything special. */
1594 if (TREE_CODE (retval_rhs) == RESULT_DECL)
1595 expand_value_return (result_rtl);
1597 /* If the result is an aggregate that is being returned in one (or more)
1598 registers, load the registers here. The compiler currently can't handle
1599 copying a BLKmode value into registers. We could put this code in a
1600 more general area (for use by everyone instead of just function
1601 call/return), but until this feature is generally usable it is kept here
1602 (and in expand_call). */
1604 else if (retval_rhs != 0
1605 && TYPE_MODE (TREE_TYPE (retval_rhs)) == BLKmode
1606 && REG_P (result_rtl))
1608 int i;
1609 unsigned HOST_WIDE_INT bitpos, xbitpos;
1610 unsigned HOST_WIDE_INT padding_correction = 0;
1611 unsigned HOST_WIDE_INT bytes
1612 = int_size_in_bytes (TREE_TYPE (retval_rhs));
1613 int n_regs = (bytes + UNITS_PER_WORD - 1) / UNITS_PER_WORD;
1614 unsigned int bitsize
1615 = MIN (TYPE_ALIGN (TREE_TYPE (retval_rhs)), BITS_PER_WORD);
1616 rtx *result_pseudos = alloca (sizeof (rtx) * n_regs);
1617 rtx result_reg, src = NULL_RTX, dst = NULL_RTX;
1618 rtx result_val = expand_expr (retval_rhs, NULL_RTX, VOIDmode, 0);
1619 enum machine_mode tmpmode, result_reg_mode;
1621 if (bytes == 0)
1623 expand_null_return ();
1624 return;
1627 /* If the structure doesn't take up a whole number of words, see
1628 whether the register value should be padded on the left or on
1629 the right. Set PADDING_CORRECTION to the number of padding
1630 bits needed on the left side.
1632 In most ABIs, the structure will be returned at the least end of
1633 the register, which translates to right padding on little-endian
1634 targets and left padding on big-endian targets. The opposite
1635 holds if the structure is returned at the most significant
1636 end of the register. */
1637 if (bytes % UNITS_PER_WORD != 0
1638 && (targetm.calls.return_in_msb (TREE_TYPE (retval_rhs))
1639 ? !BYTES_BIG_ENDIAN
1640 : BYTES_BIG_ENDIAN))
1641 padding_correction = (BITS_PER_WORD - ((bytes % UNITS_PER_WORD)
1642 * BITS_PER_UNIT));
1644 /* Copy the structure BITSIZE bits at a time. */
1645 for (bitpos = 0, xbitpos = padding_correction;
1646 bitpos < bytes * BITS_PER_UNIT;
1647 bitpos += bitsize, xbitpos += bitsize)
1649 /* We need a new destination pseudo each time xbitpos is
1650 on a word boundary and when xbitpos == padding_correction
1651 (the first time through). */
1652 if (xbitpos % BITS_PER_WORD == 0
1653 || xbitpos == padding_correction)
1655 /* Generate an appropriate register. */
1656 dst = gen_reg_rtx (word_mode);
1657 result_pseudos[xbitpos / BITS_PER_WORD] = dst;
1659 /* Clear the destination before we move anything into it. */
1660 emit_move_insn (dst, CONST0_RTX (GET_MODE (dst)));
1663 /* We need a new source operand each time bitpos is on a word
1664 boundary. */
1665 if (bitpos % BITS_PER_WORD == 0)
1666 src = operand_subword_force (result_val,
1667 bitpos / BITS_PER_WORD,
1668 BLKmode);
1670 /* Use bitpos for the source extraction (left justified) and
1671 xbitpos for the destination store (right justified). */
1672 store_bit_field (dst, bitsize, xbitpos % BITS_PER_WORD, word_mode,
1673 extract_bit_field (src, bitsize,
1674 bitpos % BITS_PER_WORD, 1,
1675 NULL_RTX, word_mode, word_mode));
1678 tmpmode = GET_MODE (result_rtl);
1679 if (tmpmode == BLKmode)
1681 /* Find the smallest integer mode large enough to hold the
1682 entire structure and use that mode instead of BLKmode
1683 on the USE insn for the return register. */
1684 for (tmpmode = GET_CLASS_NARROWEST_MODE (MODE_INT);
1685 tmpmode != VOIDmode;
1686 tmpmode = GET_MODE_WIDER_MODE (tmpmode))
1687 /* Have we found a large enough mode? */
1688 if (GET_MODE_SIZE (tmpmode) >= bytes)
1689 break;
1691 /* A suitable mode should have been found. */
1692 gcc_assert (tmpmode != VOIDmode);
1694 PUT_MODE (result_rtl, tmpmode);
1697 if (GET_MODE_SIZE (tmpmode) < GET_MODE_SIZE (word_mode))
1698 result_reg_mode = word_mode;
1699 else
1700 result_reg_mode = tmpmode;
1701 result_reg = gen_reg_rtx (result_reg_mode);
1703 for (i = 0; i < n_regs; i++)
1704 emit_move_insn (operand_subword (result_reg, i, 0, result_reg_mode),
1705 result_pseudos[i]);
1707 if (tmpmode != result_reg_mode)
1708 result_reg = gen_lowpart (tmpmode, result_reg);
1710 expand_value_return (result_reg);
1712 else if (retval_rhs != 0
1713 && !VOID_TYPE_P (TREE_TYPE (retval_rhs))
1714 && (REG_P (result_rtl)
1715 || (GET_CODE (result_rtl) == PARALLEL)))
1717 /* Calculate the return value into a temporary (usually a pseudo
1718 reg). */
1719 tree ot = TREE_TYPE (DECL_RESULT (current_function_decl));
1720 tree nt = build_qualified_type (ot, TYPE_QUALS (ot) | TYPE_QUAL_CONST);
1722 val = assign_temp (nt, 0, 0, 1);
1723 val = expand_expr (retval_rhs, val, GET_MODE (val), 0);
1724 val = force_not_mem (val);
1725 /* Return the calculated value. */
1726 expand_value_return (val);
1728 else
1730 /* No hard reg used; calculate value into hard return reg. */
1731 expand_expr (retval, const0_rtx, VOIDmode, 0);
1732 expand_value_return (result_rtl);
1736 /* Given a pointer to a BLOCK node return nonzero if (and only if) the node
1737 in question represents the outermost pair of curly braces (i.e. the "body
1738 block") of a function or method.
1740 For any BLOCK node representing a "body block" of a function or method, the
1741 BLOCK_SUPERCONTEXT of the node will point to another BLOCK node which
1742 represents the outermost (function) scope for the function or method (i.e.
1743 the one which includes the formal parameters). The BLOCK_SUPERCONTEXT of
1744 *that* node in turn will point to the relevant FUNCTION_DECL node. */
1747 is_body_block (tree stmt)
1749 if (lang_hooks.no_body_blocks)
1750 return 0;
1752 if (TREE_CODE (stmt) == BLOCK)
1754 tree parent = BLOCK_SUPERCONTEXT (stmt);
1756 if (parent && TREE_CODE (parent) == BLOCK)
1758 tree grandparent = BLOCK_SUPERCONTEXT (parent);
1760 if (grandparent && TREE_CODE (grandparent) == FUNCTION_DECL)
1761 return 1;
1765 return 0;
1768 /* Emit code to restore vital registers at the beginning of a nonlocal goto
1769 handler. */
1770 static void
1771 expand_nl_goto_receiver (void)
1773 /* Clobber the FP when we get here, so we have to make sure it's
1774 marked as used by this function. */
1775 emit_insn (gen_rtx_USE (VOIDmode, hard_frame_pointer_rtx));
1777 /* Mark the static chain as clobbered here so life information
1778 doesn't get messed up for it. */
1779 emit_insn (gen_rtx_CLOBBER (VOIDmode, static_chain_rtx));
1781 #ifdef HAVE_nonlocal_goto
1782 if (! HAVE_nonlocal_goto)
1783 #endif
1784 /* First adjust our frame pointer to its actual value. It was
1785 previously set to the start of the virtual area corresponding to
1786 the stacked variables when we branched here and now needs to be
1787 adjusted to the actual hardware fp value.
1789 Assignments are to virtual registers are converted by
1790 instantiate_virtual_regs into the corresponding assignment
1791 to the underlying register (fp in this case) that makes
1792 the original assignment true.
1793 So the following insn will actually be
1794 decrementing fp by STARTING_FRAME_OFFSET. */
1795 emit_move_insn (virtual_stack_vars_rtx, hard_frame_pointer_rtx);
1797 #if ARG_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1798 if (fixed_regs[ARG_POINTER_REGNUM])
1800 #ifdef ELIMINABLE_REGS
1801 /* If the argument pointer can be eliminated in favor of the
1802 frame pointer, we don't need to restore it. We assume here
1803 that if such an elimination is present, it can always be used.
1804 This is the case on all known machines; if we don't make this
1805 assumption, we do unnecessary saving on many machines. */
1806 static const struct elims {const int from, to;} elim_regs[] = ELIMINABLE_REGS;
1807 size_t i;
1809 for (i = 0; i < ARRAY_SIZE (elim_regs); i++)
1810 if (elim_regs[i].from == ARG_POINTER_REGNUM
1811 && elim_regs[i].to == HARD_FRAME_POINTER_REGNUM)
1812 break;
1814 if (i == ARRAY_SIZE (elim_regs))
1815 #endif
1817 /* Now restore our arg pointer from the address at which it
1818 was saved in our stack frame. */
1819 emit_move_insn (virtual_incoming_args_rtx,
1820 copy_to_reg (get_arg_pointer_save_area (cfun)));
1823 #endif
1825 #ifdef HAVE_nonlocal_goto_receiver
1826 if (HAVE_nonlocal_goto_receiver)
1827 emit_insn (gen_nonlocal_goto_receiver ());
1828 #endif
1830 /* @@@ This is a kludge. Not all machine descriptions define a blockage
1831 insn, but we must not allow the code we just generated to be reordered
1832 by scheduling. Specifically, the update of the frame pointer must
1833 happen immediately, not later. So emit an ASM_INPUT to act as blockage
1834 insn. */
1835 emit_insn (gen_rtx_ASM_INPUT (VOIDmode, ""));
1838 /* Generate RTL for the automatic variable declaration DECL.
1839 (Other kinds of declarations are simply ignored if seen here.) */
1841 void
1842 expand_decl (tree decl)
1844 tree type;
1846 type = TREE_TYPE (decl);
1848 /* For a CONST_DECL, set mode, alignment, and sizes from those of the
1849 type in case this node is used in a reference. */
1850 if (TREE_CODE (decl) == CONST_DECL)
1852 DECL_MODE (decl) = TYPE_MODE (type);
1853 DECL_ALIGN (decl) = TYPE_ALIGN (type);
1854 DECL_SIZE (decl) = TYPE_SIZE (type);
1855 DECL_SIZE_UNIT (decl) = TYPE_SIZE_UNIT (type);
1856 return;
1859 /* Otherwise, only automatic variables need any expansion done. Static and
1860 external variables, and external functions, will be handled by
1861 `assemble_variable' (called from finish_decl). TYPE_DECL requires
1862 nothing. PARM_DECLs are handled in `assign_parms'. */
1863 if (TREE_CODE (decl) != VAR_DECL)
1864 return;
1866 if (TREE_STATIC (decl) || DECL_EXTERNAL (decl))
1867 return;
1869 /* Create the RTL representation for the variable. */
1871 if (type == error_mark_node)
1872 SET_DECL_RTL (decl, gen_rtx_MEM (BLKmode, const0_rtx));
1874 else if (DECL_SIZE (decl) == 0)
1875 /* Variable with incomplete type. */
1877 rtx x;
1878 if (DECL_INITIAL (decl) == 0)
1879 /* Error message was already done; now avoid a crash. */
1880 x = gen_rtx_MEM (BLKmode, const0_rtx);
1881 else
1882 /* An initializer is going to decide the size of this array.
1883 Until we know the size, represent its address with a reg. */
1884 x = gen_rtx_MEM (BLKmode, gen_reg_rtx (Pmode));
1886 set_mem_attributes (x, decl, 1);
1887 SET_DECL_RTL (decl, x);
1889 else if (use_register_for_decl (decl))
1891 /* Automatic variable that can go in a register. */
1892 int unsignedp = TYPE_UNSIGNED (type);
1893 enum machine_mode reg_mode
1894 = promote_mode (type, DECL_MODE (decl), &unsignedp, 0);
1896 SET_DECL_RTL (decl, gen_reg_rtx (reg_mode));
1898 /* Note if the object is a user variable. */
1899 if (!DECL_ARTIFICIAL (decl))
1901 mark_user_reg (DECL_RTL (decl));
1903 /* Trust user variables which have a pointer type to really
1904 be pointers. Do not trust compiler generated temporaries
1905 as our type system is totally busted as it relates to
1906 pointer arithmetic which translates into lots of compiler
1907 generated objects with pointer types, but which are not really
1908 pointers. */
1909 if (POINTER_TYPE_P (type))
1910 mark_reg_pointer (DECL_RTL (decl),
1911 TYPE_ALIGN (TREE_TYPE (TREE_TYPE (decl))));
1915 else if (TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST
1916 && ! (flag_stack_check && ! STACK_CHECK_BUILTIN
1917 && 0 < compare_tree_int (DECL_SIZE_UNIT (decl),
1918 STACK_CHECK_MAX_VAR_SIZE)))
1920 /* Variable of fixed size that goes on the stack. */
1921 rtx oldaddr = 0;
1922 rtx addr;
1923 rtx x;
1925 /* If we previously made RTL for this decl, it must be an array
1926 whose size was determined by the initializer.
1927 The old address was a register; set that register now
1928 to the proper address. */
1929 if (DECL_RTL_SET_P (decl))
1931 gcc_assert (MEM_P (DECL_RTL (decl)));
1932 gcc_assert (REG_P (XEXP (DECL_RTL (decl), 0)));
1933 oldaddr = XEXP (DECL_RTL (decl), 0);
1936 /* Set alignment we actually gave this decl. */
1937 DECL_ALIGN (decl) = (DECL_MODE (decl) == BLKmode ? BIGGEST_ALIGNMENT
1938 : GET_MODE_BITSIZE (DECL_MODE (decl)));
1939 DECL_USER_ALIGN (decl) = 0;
1941 x = assign_temp (decl, 1, 1, 1);
1942 set_mem_attributes (x, decl, 1);
1943 SET_DECL_RTL (decl, x);
1945 if (oldaddr)
1947 addr = force_operand (XEXP (DECL_RTL (decl), 0), oldaddr);
1948 if (addr != oldaddr)
1949 emit_move_insn (oldaddr, addr);
1952 else
1953 /* Dynamic-size object: must push space on the stack. */
1955 rtx address, size, x;
1957 /* Record the stack pointer on entry to block, if have
1958 not already done so. */
1959 do_pending_stack_adjust ();
1961 /* Compute the variable's size, in bytes. This will expand any
1962 needed SAVE_EXPRs for the first time. */
1963 size = expand_expr (DECL_SIZE_UNIT (decl), NULL_RTX, VOIDmode, 0);
1964 free_temp_slots ();
1966 /* Allocate space on the stack for the variable. Note that
1967 DECL_ALIGN says how the variable is to be aligned and we
1968 cannot use it to conclude anything about the alignment of
1969 the size. */
1970 address = allocate_dynamic_stack_space (size, NULL_RTX,
1971 TYPE_ALIGN (TREE_TYPE (decl)));
1973 /* Reference the variable indirect through that rtx. */
1974 x = gen_rtx_MEM (DECL_MODE (decl), address);
1975 set_mem_attributes (x, decl, 1);
1976 SET_DECL_RTL (decl, x);
1979 /* Indicate the alignment we actually gave this variable. */
1980 #ifdef STACK_BOUNDARY
1981 DECL_ALIGN (decl) = STACK_BOUNDARY;
1982 #else
1983 DECL_ALIGN (decl) = BIGGEST_ALIGNMENT;
1984 #endif
1985 DECL_USER_ALIGN (decl) = 0;
1989 /* Emit code to save the current value of stack. */
1991 expand_stack_save (void)
1993 rtx ret = NULL_RTX;
1995 do_pending_stack_adjust ();
1996 emit_stack_save (SAVE_BLOCK, &ret, NULL_RTX);
1997 return ret;
2000 /* Emit code to restore the current value of stack. */
2001 void
2002 expand_stack_restore (tree var)
2004 rtx sa = DECL_RTL (var);
2006 emit_stack_restore (SAVE_BLOCK, sa, NULL_RTX);
2009 /* DECL is an anonymous union. CLEANUP is a cleanup for DECL.
2010 DECL_ELTS is the list of elements that belong to DECL's type.
2011 In each, the TREE_VALUE is a VAR_DECL, and the TREE_PURPOSE a cleanup. */
2013 void
2014 expand_anon_union_decl (tree decl, tree cleanup ATTRIBUTE_UNUSED,
2015 tree decl_elts)
2017 rtx x;
2018 tree t;
2020 /* If any of the elements are addressable, so is the entire union. */
2021 for (t = decl_elts; t; t = TREE_CHAIN (t))
2022 if (TREE_ADDRESSABLE (TREE_VALUE (t)))
2024 TREE_ADDRESSABLE (decl) = 1;
2025 break;
2028 expand_decl (decl);
2029 x = DECL_RTL (decl);
2031 /* Go through the elements, assigning RTL to each. */
2032 for (t = decl_elts; t; t = TREE_CHAIN (t))
2034 tree decl_elt = TREE_VALUE (t);
2035 enum machine_mode mode = TYPE_MODE (TREE_TYPE (decl_elt));
2036 rtx decl_rtl;
2038 /* If any of the elements are addressable, so is the entire
2039 union. */
2040 if (TREE_USED (decl_elt))
2041 TREE_USED (decl) = 1;
2043 /* Propagate the union's alignment to the elements. */
2044 DECL_ALIGN (decl_elt) = DECL_ALIGN (decl);
2045 DECL_USER_ALIGN (decl_elt) = DECL_USER_ALIGN (decl);
2047 /* If the element has BLKmode and the union doesn't, the union is
2048 aligned such that the element doesn't need to have BLKmode, so
2049 change the element's mode to the appropriate one for its size. */
2050 if (mode == BLKmode && DECL_MODE (decl) != BLKmode)
2051 DECL_MODE (decl_elt) = mode
2052 = mode_for_size_tree (DECL_SIZE (decl_elt), MODE_INT, 1);
2054 if (mode == GET_MODE (x))
2055 decl_rtl = x;
2056 else if (MEM_P (x))
2057 /* (SUBREG (MEM ...)) at RTL generation time is invalid, so we
2058 instead create a new MEM rtx with the proper mode. */
2059 decl_rtl = adjust_address_nv (x, mode, 0);
2060 else
2062 gcc_assert (REG_P (x));
2063 decl_rtl = gen_lowpart_SUBREG (mode, x);
2065 SET_DECL_RTL (decl_elt, decl_rtl);
2069 /* Do the insertion of a case label into case_list. The labels are
2070 fed to us in descending order from the sorted vector of case labels used
2071 in the tree part of the middle end. So the list we construct is
2072 sorted in ascending order. The bounds on the case range, LOW and HIGH,
2073 are converted to case's index type TYPE. */
2075 static struct case_node *
2076 add_case_node (struct case_node *head, tree type, tree low, tree high,
2077 tree label)
2079 tree min_value, max_value;
2080 struct case_node *r;
2082 gcc_assert (TREE_CODE (low) == INTEGER_CST);
2083 gcc_assert (!high || TREE_CODE (high) == INTEGER_CST);
2085 min_value = TYPE_MIN_VALUE (type);
2086 max_value = TYPE_MAX_VALUE (type);
2088 /* If there's no HIGH value, then this is not a case range; it's
2089 just a simple case label. But that's just a degenerate case
2090 range.
2091 If the bounds are equal, turn this into the one-value case. */
2092 if (!high || tree_int_cst_equal (low, high))
2094 /* If the simple case value is unreachable, ignore it. */
2095 if ((TREE_CODE (min_value) == INTEGER_CST
2096 && tree_int_cst_compare (low, min_value) < 0)
2097 || (TREE_CODE (max_value) == INTEGER_CST
2098 && tree_int_cst_compare (low, max_value) > 0))
2099 return head;
2100 low = fold_convert (type, low);
2101 high = low;
2103 else
2105 /* If the entire case range is unreachable, ignore it. */
2106 if ((TREE_CODE (min_value) == INTEGER_CST
2107 && tree_int_cst_compare (high, min_value) < 0)
2108 || (TREE_CODE (max_value) == INTEGER_CST
2109 && tree_int_cst_compare (low, max_value) > 0))
2110 return head;
2112 /* If the lower bound is less than the index type's minimum
2113 value, truncate the range bounds. */
2114 if (TREE_CODE (min_value) == INTEGER_CST
2115 && tree_int_cst_compare (low, min_value) < 0)
2116 low = min_value;
2117 low = fold_convert (type, low);
2119 /* If the upper bound is greater than the index type's maximum
2120 value, truncate the range bounds. */
2121 if (TREE_CODE (max_value) == INTEGER_CST
2122 && tree_int_cst_compare (high, max_value) > 0)
2123 high = max_value;
2124 high = fold_convert (type, high);
2128 /* Add this label to the chain. Make sure to drop overflow flags. */
2129 r = ggc_alloc (sizeof (struct case_node));
2130 r->low = build_int_cst_wide (TREE_TYPE (low), TREE_INT_CST_LOW (low),
2131 TREE_INT_CST_HIGH (low));
2132 r->high = build_int_cst_wide (TREE_TYPE (high), TREE_INT_CST_LOW (high),
2133 TREE_INT_CST_HIGH (high));
2134 r->code_label = label;
2135 r->parent = r->left = NULL;
2136 r->right = head;
2137 return r;
2140 /* Maximum number of case bit tests. */
2141 #define MAX_CASE_BIT_TESTS 3
2143 /* By default, enable case bit tests on targets with ashlsi3. */
2144 #ifndef CASE_USE_BIT_TESTS
2145 #define CASE_USE_BIT_TESTS (ashl_optab->handlers[word_mode].insn_code \
2146 != CODE_FOR_nothing)
2147 #endif
2150 /* A case_bit_test represents a set of case nodes that may be
2151 selected from using a bit-wise comparison. HI and LO hold
2152 the integer to be tested against, LABEL contains the label
2153 to jump to upon success and BITS counts the number of case
2154 nodes handled by this test, typically the number of bits
2155 set in HI:LO. */
2157 struct case_bit_test
2159 HOST_WIDE_INT hi;
2160 HOST_WIDE_INT lo;
2161 rtx label;
2162 int bits;
2165 /* Determine whether "1 << x" is relatively cheap in word_mode. */
2167 static
2168 bool lshift_cheap_p (void)
2170 static bool init = false;
2171 static bool cheap = true;
2173 if (!init)
2175 rtx reg = gen_rtx_REG (word_mode, 10000);
2176 int cost = rtx_cost (gen_rtx_ASHIFT (word_mode, const1_rtx, reg), SET);
2177 cheap = cost < COSTS_N_INSNS (3);
2178 init = true;
2181 return cheap;
2184 /* Comparison function for qsort to order bit tests by decreasing
2185 number of case nodes, i.e. the node with the most cases gets
2186 tested first. */
2188 static int
2189 case_bit_test_cmp (const void *p1, const void *p2)
2191 const struct case_bit_test *d1 = p1;
2192 const struct case_bit_test *d2 = p2;
2194 return d2->bits - d1->bits;
2197 /* Expand a switch statement by a short sequence of bit-wise
2198 comparisons. "switch(x)" is effectively converted into
2199 "if ((1 << (x-MINVAL)) & CST)" where CST and MINVAL are
2200 integer constants.
2202 INDEX_EXPR is the value being switched on, which is of
2203 type INDEX_TYPE. MINVAL is the lowest case value of in
2204 the case nodes, of INDEX_TYPE type, and RANGE is highest
2205 value minus MINVAL, also of type INDEX_TYPE. NODES is
2206 the set of case nodes, and DEFAULT_LABEL is the label to
2207 branch to should none of the cases match.
2209 There *MUST* be MAX_CASE_BIT_TESTS or less unique case
2210 node targets. */
2212 static void
2213 emit_case_bit_tests (tree index_type, tree index_expr, tree minval,
2214 tree range, case_node_ptr nodes, rtx default_label)
2216 struct case_bit_test test[MAX_CASE_BIT_TESTS];
2217 enum machine_mode mode;
2218 rtx expr, index, label;
2219 unsigned int i,j,lo,hi;
2220 struct case_node *n;
2221 unsigned int count;
2223 count = 0;
2224 for (n = nodes; n; n = n->right)
2226 label = label_rtx (n->code_label);
2227 for (i = 0; i < count; i++)
2228 if (label == test[i].label)
2229 break;
2231 if (i == count)
2233 gcc_assert (count < MAX_CASE_BIT_TESTS);
2234 test[i].hi = 0;
2235 test[i].lo = 0;
2236 test[i].label = label;
2237 test[i].bits = 1;
2238 count++;
2240 else
2241 test[i].bits++;
2243 lo = tree_low_cst (fold_build2 (MINUS_EXPR, index_type,
2244 n->low, minval), 1);
2245 hi = tree_low_cst (fold_build2 (MINUS_EXPR, index_type,
2246 n->high, minval), 1);
2247 for (j = lo; j <= hi; j++)
2248 if (j >= HOST_BITS_PER_WIDE_INT)
2249 test[i].hi |= (HOST_WIDE_INT) 1 << (j - HOST_BITS_PER_INT);
2250 else
2251 test[i].lo |= (HOST_WIDE_INT) 1 << j;
2254 qsort (test, count, sizeof(*test), case_bit_test_cmp);
2256 index_expr = fold_build2 (MINUS_EXPR, index_type,
2257 fold_convert (index_type, index_expr),
2258 fold_convert (index_type, minval));
2259 index = expand_expr (index_expr, NULL_RTX, VOIDmode, 0);
2260 do_pending_stack_adjust ();
2262 mode = TYPE_MODE (index_type);
2263 expr = expand_expr (range, NULL_RTX, VOIDmode, 0);
2264 emit_cmp_and_jump_insns (index, expr, GTU, NULL_RTX, mode, 1,
2265 default_label);
2267 index = convert_to_mode (word_mode, index, 0);
2268 index = expand_binop (word_mode, ashl_optab, const1_rtx,
2269 index, NULL_RTX, 1, OPTAB_WIDEN);
2271 for (i = 0; i < count; i++)
2273 expr = immed_double_const (test[i].lo, test[i].hi, word_mode);
2274 expr = expand_binop (word_mode, and_optab, index, expr,
2275 NULL_RTX, 1, OPTAB_WIDEN);
2276 emit_cmp_and_jump_insns (expr, const0_rtx, NE, NULL_RTX,
2277 word_mode, 1, test[i].label);
2280 emit_jump (default_label);
2283 #ifndef HAVE_casesi
2284 #define HAVE_casesi 0
2285 #endif
2287 #ifndef HAVE_tablejump
2288 #define HAVE_tablejump 0
2289 #endif
2291 /* Terminate a case (Pascal/Ada) or switch (C) statement
2292 in which ORIG_INDEX is the expression to be tested.
2293 If ORIG_TYPE is not NULL, it is the original ORIG_INDEX
2294 type as given in the source before any compiler conversions.
2295 Generate the code to test it and jump to the right place. */
2297 void
2298 expand_case (tree exp)
2300 tree minval = NULL_TREE, maxval = NULL_TREE, range = NULL_TREE;
2301 rtx default_label = 0;
2302 struct case_node *n;
2303 unsigned int count, uniq;
2304 rtx index;
2305 rtx table_label;
2306 int ncases;
2307 rtx *labelvec;
2308 int i, fail;
2309 rtx before_case, end, lab;
2311 tree vec = SWITCH_LABELS (exp);
2312 tree orig_type = TREE_TYPE (exp);
2313 tree index_expr = SWITCH_COND (exp);
2314 tree index_type = TREE_TYPE (index_expr);
2315 int unsignedp = TYPE_UNSIGNED (index_type);
2317 /* The insn after which the case dispatch should finally
2318 be emitted. Zero for a dummy. */
2319 rtx start;
2321 /* A list of case labels; it is first built as a list and it may then
2322 be rearranged into a nearly balanced binary tree. */
2323 struct case_node *case_list = 0;
2325 /* Label to jump to if no case matches. */
2326 tree default_label_decl;
2328 /* The switch body is lowered in gimplify.c, we should never have
2329 switches with a non-NULL SWITCH_BODY here. */
2330 gcc_assert (!SWITCH_BODY (exp));
2331 gcc_assert (SWITCH_LABELS (exp));
2333 do_pending_stack_adjust ();
2335 /* An ERROR_MARK occurs for various reasons including invalid data type. */
2336 if (index_type != error_mark_node)
2338 tree elt;
2339 bitmap label_bitmap;
2341 /* cleanup_tree_cfg removes all SWITCH_EXPR with their index
2342 expressions being INTEGER_CST. */
2343 gcc_assert (TREE_CODE (index_expr) != INTEGER_CST);
2345 /* The default case is at the end of TREE_VEC. */
2346 elt = TREE_VEC_ELT (vec, TREE_VEC_LENGTH (vec) - 1);
2347 gcc_assert (!CASE_HIGH (elt));
2348 gcc_assert (!CASE_LOW (elt));
2349 default_label_decl = CASE_LABEL (elt);
2351 for (i = TREE_VEC_LENGTH (vec) - 1; --i >= 0; )
2353 tree low, high;
2354 elt = TREE_VEC_ELT (vec, i);
2356 low = CASE_LOW (elt);
2357 gcc_assert (low);
2358 high = CASE_HIGH (elt);
2360 /* Discard empty ranges. */
2361 if (high && INT_CST_LT (high, low))
2362 continue;
2364 case_list = add_case_node (case_list, index_type, low, high,
2365 CASE_LABEL (elt));
2369 /* Make sure start points to something that won't need any
2370 transformation before the end of this function. */
2371 start = get_last_insn ();
2372 if (! NOTE_P (start))
2374 emit_note (NOTE_INSN_DELETED);
2375 start = get_last_insn ();
2378 default_label = label_rtx (default_label_decl);
2380 before_case = get_last_insn ();
2382 /* Get upper and lower bounds of case values. */
2384 uniq = 0;
2385 count = 0;
2386 label_bitmap = BITMAP_ALLOC (NULL);
2387 for (n = case_list; n; n = n->right)
2389 /* Count the elements and track the largest and smallest
2390 of them (treating them as signed even if they are not). */
2391 if (count++ == 0)
2393 minval = n->low;
2394 maxval = n->high;
2396 else
2398 if (INT_CST_LT (n->low, minval))
2399 minval = n->low;
2400 if (INT_CST_LT (maxval, n->high))
2401 maxval = n->high;
2403 /* A range counts double, since it requires two compares. */
2404 if (! tree_int_cst_equal (n->low, n->high))
2405 count++;
2407 /* If we have not seen this label yet, then increase the
2408 number of unique case node targets seen. */
2409 lab = label_rtx (n->code_label);
2410 if (!bitmap_bit_p (label_bitmap, CODE_LABEL_NUMBER (lab)))
2412 bitmap_set_bit (label_bitmap, CODE_LABEL_NUMBER (lab));
2413 uniq++;
2417 BITMAP_FREE (label_bitmap);
2419 /* cleanup_tree_cfg removes all SWITCH_EXPR with a single
2420 destination, such as one with a default case only. However,
2421 it doesn't remove cases that are out of range for the switch
2422 type, so we may still get a zero here. */
2423 if (count == 0)
2425 emit_jump (default_label);
2426 return;
2429 /* Compute span of values. */
2430 range = fold_build2 (MINUS_EXPR, index_type, maxval, minval);
2432 /* Try implementing this switch statement by a short sequence of
2433 bit-wise comparisons. However, we let the binary-tree case
2434 below handle constant index expressions. */
2435 if (CASE_USE_BIT_TESTS
2436 && ! TREE_CONSTANT (index_expr)
2437 && compare_tree_int (range, GET_MODE_BITSIZE (word_mode)) < 0
2438 && compare_tree_int (range, 0) > 0
2439 && lshift_cheap_p ()
2440 && ((uniq == 1 && count >= 3)
2441 || (uniq == 2 && count >= 5)
2442 || (uniq == 3 && count >= 6)))
2444 /* Optimize the case where all the case values fit in a
2445 word without having to subtract MINVAL. In this case,
2446 we can optimize away the subtraction. */
2447 if (compare_tree_int (minval, 0) > 0
2448 && compare_tree_int (maxval, GET_MODE_BITSIZE (word_mode)) < 0)
2450 minval = build_int_cst (index_type, 0);
2451 range = maxval;
2453 emit_case_bit_tests (index_type, index_expr, minval, range,
2454 case_list, default_label);
2457 /* If range of values is much bigger than number of values,
2458 make a sequence of conditional branches instead of a dispatch.
2459 If the switch-index is a constant, do it this way
2460 because we can optimize it. */
2462 else if (count < case_values_threshold ()
2463 || compare_tree_int (range,
2464 (optimize_size ? 3 : 10) * count) > 0
2465 /* RANGE may be signed, and really large ranges will show up
2466 as negative numbers. */
2467 || compare_tree_int (range, 0) < 0
2468 #ifndef ASM_OUTPUT_ADDR_DIFF_ELT
2469 || flag_pic
2470 #endif
2471 || !flag_jump_tables
2472 || TREE_CONSTANT (index_expr)
2473 /* If neither casesi or tablejump is available, we can
2474 only go this way. */
2475 || (!HAVE_casesi && !HAVE_tablejump))
2477 index = expand_expr (index_expr, NULL_RTX, VOIDmode, 0);
2479 /* If the index is a short or char that we do not have
2480 an insn to handle comparisons directly, convert it to
2481 a full integer now, rather than letting each comparison
2482 generate the conversion. */
2484 if (GET_MODE_CLASS (GET_MODE (index)) == MODE_INT
2485 && ! have_insn_for (COMPARE, GET_MODE (index)))
2487 enum machine_mode wider_mode;
2488 for (wider_mode = GET_MODE (index); wider_mode != VOIDmode;
2489 wider_mode = GET_MODE_WIDER_MODE (wider_mode))
2490 if (have_insn_for (COMPARE, wider_mode))
2492 index = convert_to_mode (wider_mode, index, unsignedp);
2493 break;
2497 do_pending_stack_adjust ();
2499 if (MEM_P (index))
2500 index = copy_to_reg (index);
2502 /* We generate a binary decision tree to select the
2503 appropriate target code. This is done as follows:
2505 The list of cases is rearranged into a binary tree,
2506 nearly optimal assuming equal probability for each case.
2508 The tree is transformed into RTL, eliminating
2509 redundant test conditions at the same time.
2511 If program flow could reach the end of the
2512 decision tree an unconditional jump to the
2513 default code is emitted. */
2515 use_cost_table
2516 = (TREE_CODE (orig_type) != ENUMERAL_TYPE
2517 && estimate_case_costs (case_list));
2518 balance_case_nodes (&case_list, NULL);
2519 emit_case_nodes (index, case_list, default_label, index_type);
2520 emit_jump (default_label);
2522 else
2524 table_label = gen_label_rtx ();
2525 if (! try_casesi (index_type, index_expr, minval, range,
2526 table_label, default_label))
2528 bool ok;
2530 /* Index jumptables from zero for suitable values of
2531 minval to avoid a subtraction. */
2532 if (! optimize_size
2533 && compare_tree_int (minval, 0) > 0
2534 && compare_tree_int (minval, 3) < 0)
2536 minval = build_int_cst (index_type, 0);
2537 range = maxval;
2540 ok = try_tablejump (index_type, index_expr, minval, range,
2541 table_label, default_label);
2542 gcc_assert (ok);
2545 /* Get table of labels to jump to, in order of case index. */
2547 ncases = tree_low_cst (range, 0) + 1;
2548 labelvec = alloca (ncases * sizeof (rtx));
2549 memset (labelvec, 0, ncases * sizeof (rtx));
2551 for (n = case_list; n; n = n->right)
2553 /* Compute the low and high bounds relative to the minimum
2554 value since that should fit in a HOST_WIDE_INT while the
2555 actual values may not. */
2556 HOST_WIDE_INT i_low
2557 = tree_low_cst (fold_build2 (MINUS_EXPR, index_type,
2558 n->low, minval), 1);
2559 HOST_WIDE_INT i_high
2560 = tree_low_cst (fold_build2 (MINUS_EXPR, index_type,
2561 n->high, minval), 1);
2562 HOST_WIDE_INT i;
2564 for (i = i_low; i <= i_high; i ++)
2565 labelvec[i]
2566 = gen_rtx_LABEL_REF (Pmode, label_rtx (n->code_label));
2569 /* Fill in the gaps with the default. */
2570 for (i = 0; i < ncases; i++)
2571 if (labelvec[i] == 0)
2572 labelvec[i] = gen_rtx_LABEL_REF (Pmode, default_label);
2574 /* Output the table. */
2575 emit_label (table_label);
2577 if (CASE_VECTOR_PC_RELATIVE || flag_pic)
2578 emit_jump_insn (gen_rtx_ADDR_DIFF_VEC (CASE_VECTOR_MODE,
2579 gen_rtx_LABEL_REF (Pmode, table_label),
2580 gen_rtvec_v (ncases, labelvec),
2581 const0_rtx, const0_rtx));
2582 else
2583 emit_jump_insn (gen_rtx_ADDR_VEC (CASE_VECTOR_MODE,
2584 gen_rtvec_v (ncases, labelvec)));
2586 /* Record no drop-through after the table. */
2587 emit_barrier ();
2590 before_case = NEXT_INSN (before_case);
2591 end = get_last_insn ();
2592 fail = squeeze_notes (&before_case, &end);
2593 gcc_assert (!fail);
2594 reorder_insns (before_case, end, start);
2597 free_temp_slots ();
2600 /* Generate code to jump to LABEL if OP1 and OP2 are equal. */
2602 static void
2603 do_jump_if_equal (rtx op1, rtx op2, rtx label, int unsignedp)
2605 if (GET_CODE (op1) == CONST_INT && GET_CODE (op2) == CONST_INT)
2607 if (op1 == op2)
2608 emit_jump (label);
2610 else
2611 emit_cmp_and_jump_insns (op1, op2, EQ, NULL_RTX,
2612 (GET_MODE (op1) == VOIDmode
2613 ? GET_MODE (op2) : GET_MODE (op1)),
2614 unsignedp, label);
2617 /* Not all case values are encountered equally. This function
2618 uses a heuristic to weight case labels, in cases where that
2619 looks like a reasonable thing to do.
2621 Right now, all we try to guess is text, and we establish the
2622 following weights:
2624 chars above space: 16
2625 digits: 16
2626 default: 12
2627 space, punct: 8
2628 tab: 4
2629 newline: 2
2630 other "\" chars: 1
2631 remaining chars: 0
2633 If we find any cases in the switch that are not either -1 or in the range
2634 of valid ASCII characters, or are control characters other than those
2635 commonly used with "\", don't treat this switch scanning text.
2637 Return 1 if these nodes are suitable for cost estimation, otherwise
2638 return 0. */
2640 static int
2641 estimate_case_costs (case_node_ptr node)
2643 tree min_ascii = integer_minus_one_node;
2644 tree max_ascii = build_int_cst (TREE_TYPE (node->high), 127);
2645 case_node_ptr n;
2646 int i;
2648 /* If we haven't already made the cost table, make it now. Note that the
2649 lower bound of the table is -1, not zero. */
2651 if (! cost_table_initialized)
2653 cost_table_initialized = 1;
2655 for (i = 0; i < 128; i++)
2657 if (ISALNUM (i))
2658 COST_TABLE (i) = 16;
2659 else if (ISPUNCT (i))
2660 COST_TABLE (i) = 8;
2661 else if (ISCNTRL (i))
2662 COST_TABLE (i) = -1;
2665 COST_TABLE (' ') = 8;
2666 COST_TABLE ('\t') = 4;
2667 COST_TABLE ('\0') = 4;
2668 COST_TABLE ('\n') = 2;
2669 COST_TABLE ('\f') = 1;
2670 COST_TABLE ('\v') = 1;
2671 COST_TABLE ('\b') = 1;
2674 /* See if all the case expressions look like text. It is text if the
2675 constant is >= -1 and the highest constant is <= 127. Do all comparisons
2676 as signed arithmetic since we don't want to ever access cost_table with a
2677 value less than -1. Also check that none of the constants in a range
2678 are strange control characters. */
2680 for (n = node; n; n = n->right)
2682 if ((INT_CST_LT (n->low, min_ascii)) || INT_CST_LT (max_ascii, n->high))
2683 return 0;
2685 for (i = (HOST_WIDE_INT) TREE_INT_CST_LOW (n->low);
2686 i <= (HOST_WIDE_INT) TREE_INT_CST_LOW (n->high); i++)
2687 if (COST_TABLE (i) < 0)
2688 return 0;
2691 /* All interesting values are within the range of interesting
2692 ASCII characters. */
2693 return 1;
2696 /* Take an ordered list of case nodes
2697 and transform them into a near optimal binary tree,
2698 on the assumption that any target code selection value is as
2699 likely as any other.
2701 The transformation is performed by splitting the ordered
2702 list into two equal sections plus a pivot. The parts are
2703 then attached to the pivot as left and right branches. Each
2704 branch is then transformed recursively. */
2706 static void
2707 balance_case_nodes (case_node_ptr *head, case_node_ptr parent)
2709 case_node_ptr np;
2711 np = *head;
2712 if (np)
2714 int cost = 0;
2715 int i = 0;
2716 int ranges = 0;
2717 case_node_ptr *npp;
2718 case_node_ptr left;
2720 /* Count the number of entries on branch. Also count the ranges. */
2722 while (np)
2724 if (!tree_int_cst_equal (np->low, np->high))
2726 ranges++;
2727 if (use_cost_table)
2728 cost += COST_TABLE (TREE_INT_CST_LOW (np->high));
2731 if (use_cost_table)
2732 cost += COST_TABLE (TREE_INT_CST_LOW (np->low));
2734 i++;
2735 np = np->right;
2738 if (i > 2)
2740 /* Split this list if it is long enough for that to help. */
2741 npp = head;
2742 left = *npp;
2743 if (use_cost_table)
2745 /* Find the place in the list that bisects the list's total cost,
2746 Here I gets half the total cost. */
2747 int n_moved = 0;
2748 i = (cost + 1) / 2;
2749 while (1)
2751 /* Skip nodes while their cost does not reach that amount. */
2752 if (!tree_int_cst_equal ((*npp)->low, (*npp)->high))
2753 i -= COST_TABLE (TREE_INT_CST_LOW ((*npp)->high));
2754 i -= COST_TABLE (TREE_INT_CST_LOW ((*npp)->low));
2755 if (i <= 0)
2756 break;
2757 npp = &(*npp)->right;
2758 n_moved += 1;
2760 if (n_moved == 0)
2762 /* Leave this branch lopsided, but optimize left-hand
2763 side and fill in `parent' fields for right-hand side. */
2764 np = *head;
2765 np->parent = parent;
2766 balance_case_nodes (&np->left, np);
2767 for (; np->right; np = np->right)
2768 np->right->parent = np;
2769 return;
2772 /* If there are just three nodes, split at the middle one. */
2773 else if (i == 3)
2774 npp = &(*npp)->right;
2775 else
2777 /* Find the place in the list that bisects the list's total cost,
2778 where ranges count as 2.
2779 Here I gets half the total cost. */
2780 i = (i + ranges + 1) / 2;
2781 while (1)
2783 /* Skip nodes while their cost does not reach that amount. */
2784 if (!tree_int_cst_equal ((*npp)->low, (*npp)->high))
2785 i--;
2786 i--;
2787 if (i <= 0)
2788 break;
2789 npp = &(*npp)->right;
2792 *head = np = *npp;
2793 *npp = 0;
2794 np->parent = parent;
2795 np->left = left;
2797 /* Optimize each of the two split parts. */
2798 balance_case_nodes (&np->left, np);
2799 balance_case_nodes (&np->right, np);
2801 else
2803 /* Else leave this branch as one level,
2804 but fill in `parent' fields. */
2805 np = *head;
2806 np->parent = parent;
2807 for (; np->right; np = np->right)
2808 np->right->parent = np;
2813 /* Search the parent sections of the case node tree
2814 to see if a test for the lower bound of NODE would be redundant.
2815 INDEX_TYPE is the type of the index expression.
2817 The instructions to generate the case decision tree are
2818 output in the same order as nodes are processed so it is
2819 known that if a parent node checks the range of the current
2820 node minus one that the current node is bounded at its lower
2821 span. Thus the test would be redundant. */
2823 static int
2824 node_has_low_bound (case_node_ptr node, tree index_type)
2826 tree low_minus_one;
2827 case_node_ptr pnode;
2829 /* If the lower bound of this node is the lowest value in the index type,
2830 we need not test it. */
2832 if (tree_int_cst_equal (node->low, TYPE_MIN_VALUE (index_type)))
2833 return 1;
2835 /* If this node has a left branch, the value at the left must be less
2836 than that at this node, so it cannot be bounded at the bottom and
2837 we need not bother testing any further. */
2839 if (node->left)
2840 return 0;
2842 low_minus_one = fold_build2 (MINUS_EXPR, TREE_TYPE (node->low),
2843 node->low,
2844 build_int_cst (TREE_TYPE (node->low), 1));
2846 /* If the subtraction above overflowed, we can't verify anything.
2847 Otherwise, look for a parent that tests our value - 1. */
2849 if (! tree_int_cst_lt (low_minus_one, node->low))
2850 return 0;
2852 for (pnode = node->parent; pnode; pnode = pnode->parent)
2853 if (tree_int_cst_equal (low_minus_one, pnode->high))
2854 return 1;
2856 return 0;
2859 /* Search the parent sections of the case node tree
2860 to see if a test for the upper bound of NODE would be redundant.
2861 INDEX_TYPE is the type of the index expression.
2863 The instructions to generate the case decision tree are
2864 output in the same order as nodes are processed so it is
2865 known that if a parent node checks the range of the current
2866 node plus one that the current node is bounded at its upper
2867 span. Thus the test would be redundant. */
2869 static int
2870 node_has_high_bound (case_node_ptr node, tree index_type)
2872 tree high_plus_one;
2873 case_node_ptr pnode;
2875 /* If there is no upper bound, obviously no test is needed. */
2877 if (TYPE_MAX_VALUE (index_type) == NULL)
2878 return 1;
2880 /* If the upper bound of this node is the highest value in the type
2881 of the index expression, we need not test against it. */
2883 if (tree_int_cst_equal (node->high, TYPE_MAX_VALUE (index_type)))
2884 return 1;
2886 /* If this node has a right branch, the value at the right must be greater
2887 than that at this node, so it cannot be bounded at the top and
2888 we need not bother testing any further. */
2890 if (node->right)
2891 return 0;
2893 high_plus_one = fold_build2 (PLUS_EXPR, TREE_TYPE (node->high),
2894 node->high,
2895 build_int_cst (TREE_TYPE (node->high), 1));
2897 /* If the addition above overflowed, we can't verify anything.
2898 Otherwise, look for a parent that tests our value + 1. */
2900 if (! tree_int_cst_lt (node->high, high_plus_one))
2901 return 0;
2903 for (pnode = node->parent; pnode; pnode = pnode->parent)
2904 if (tree_int_cst_equal (high_plus_one, pnode->low))
2905 return 1;
2907 return 0;
2910 /* Search the parent sections of the
2911 case node tree to see if both tests for the upper and lower
2912 bounds of NODE would be redundant. */
2914 static int
2915 node_is_bounded (case_node_ptr node, tree index_type)
2917 return (node_has_low_bound (node, index_type)
2918 && node_has_high_bound (node, index_type));
2921 /* Emit step-by-step code to select a case for the value of INDEX.
2922 The thus generated decision tree follows the form of the
2923 case-node binary tree NODE, whose nodes represent test conditions.
2924 INDEX_TYPE is the type of the index of the switch.
2926 Care is taken to prune redundant tests from the decision tree
2927 by detecting any boundary conditions already checked by
2928 emitted rtx. (See node_has_high_bound, node_has_low_bound
2929 and node_is_bounded, above.)
2931 Where the test conditions can be shown to be redundant we emit
2932 an unconditional jump to the target code. As a further
2933 optimization, the subordinates of a tree node are examined to
2934 check for bounded nodes. In this case conditional and/or
2935 unconditional jumps as a result of the boundary check for the
2936 current node are arranged to target the subordinates associated
2937 code for out of bound conditions on the current node.
2939 We can assume that when control reaches the code generated here,
2940 the index value has already been compared with the parents
2941 of this node, and determined to be on the same side of each parent
2942 as this node is. Thus, if this node tests for the value 51,
2943 and a parent tested for 52, we don't need to consider
2944 the possibility of a value greater than 51. If another parent
2945 tests for the value 50, then this node need not test anything. */
2947 static void
2948 emit_case_nodes (rtx index, case_node_ptr node, rtx default_label,
2949 tree index_type)
2951 /* If INDEX has an unsigned type, we must make unsigned branches. */
2952 int unsignedp = TYPE_UNSIGNED (index_type);
2953 enum machine_mode mode = GET_MODE (index);
2954 enum machine_mode imode = TYPE_MODE (index_type);
2956 /* Handle indices detected as constant during RTL expansion. */
2957 if (mode == VOIDmode)
2958 mode = imode;
2960 /* See if our parents have already tested everything for us.
2961 If they have, emit an unconditional jump for this node. */
2962 if (node_is_bounded (node, index_type))
2963 emit_jump (label_rtx (node->code_label));
2965 else if (tree_int_cst_equal (node->low, node->high))
2967 /* Node is single valued. First see if the index expression matches
2968 this node and then check our children, if any. */
2970 do_jump_if_equal (index,
2971 convert_modes (mode, imode,
2972 expand_expr (node->low, NULL_RTX,
2973 VOIDmode, 0),
2974 unsignedp),
2975 label_rtx (node->code_label), unsignedp);
2977 if (node->right != 0 && node->left != 0)
2979 /* This node has children on both sides.
2980 Dispatch to one side or the other
2981 by comparing the index value with this node's value.
2982 If one subtree is bounded, check that one first,
2983 so we can avoid real branches in the tree. */
2985 if (node_is_bounded (node->right, index_type))
2987 emit_cmp_and_jump_insns (index,
2988 convert_modes
2989 (mode, imode,
2990 expand_expr (node->high, NULL_RTX,
2991 VOIDmode, 0),
2992 unsignedp),
2993 GT, NULL_RTX, mode, unsignedp,
2994 label_rtx (node->right->code_label));
2995 emit_case_nodes (index, node->left, default_label, index_type);
2998 else if (node_is_bounded (node->left, index_type))
3000 emit_cmp_and_jump_insns (index,
3001 convert_modes
3002 (mode, imode,
3003 expand_expr (node->high, NULL_RTX,
3004 VOIDmode, 0),
3005 unsignedp),
3006 LT, NULL_RTX, mode, unsignedp,
3007 label_rtx (node->left->code_label));
3008 emit_case_nodes (index, node->right, default_label, index_type);
3011 /* If both children are single-valued cases with no
3012 children, finish up all the work. This way, we can save
3013 one ordered comparison. */
3014 else if (tree_int_cst_equal (node->right->low, node->right->high)
3015 && node->right->left == 0
3016 && node->right->right == 0
3017 && tree_int_cst_equal (node->left->low, node->left->high)
3018 && node->left->left == 0
3019 && node->left->right == 0)
3021 /* Neither node is bounded. First distinguish the two sides;
3022 then emit the code for one side at a time. */
3024 /* See if the value matches what the right hand side
3025 wants. */
3026 do_jump_if_equal (index,
3027 convert_modes (mode, imode,
3028 expand_expr (node->right->low,
3029 NULL_RTX,
3030 VOIDmode, 0),
3031 unsignedp),
3032 label_rtx (node->right->code_label),
3033 unsignedp);
3035 /* See if the value matches what the left hand side
3036 wants. */
3037 do_jump_if_equal (index,
3038 convert_modes (mode, imode,
3039 expand_expr (node->left->low,
3040 NULL_RTX,
3041 VOIDmode, 0),
3042 unsignedp),
3043 label_rtx (node->left->code_label),
3044 unsignedp);
3047 else
3049 /* Neither node is bounded. First distinguish the two sides;
3050 then emit the code for one side at a time. */
3052 tree test_label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
3054 /* See if the value is on the right. */
3055 emit_cmp_and_jump_insns (index,
3056 convert_modes
3057 (mode, imode,
3058 expand_expr (node->high, NULL_RTX,
3059 VOIDmode, 0),
3060 unsignedp),
3061 GT, NULL_RTX, mode, unsignedp,
3062 label_rtx (test_label));
3064 /* Value must be on the left.
3065 Handle the left-hand subtree. */
3066 emit_case_nodes (index, node->left, default_label, index_type);
3067 /* If left-hand subtree does nothing,
3068 go to default. */
3069 emit_jump (default_label);
3071 /* Code branches here for the right-hand subtree. */
3072 expand_label (test_label);
3073 emit_case_nodes (index, node->right, default_label, index_type);
3077 else if (node->right != 0 && node->left == 0)
3079 /* Here we have a right child but no left so we issue a conditional
3080 branch to default and process the right child.
3082 Omit the conditional branch to default if the right child
3083 does not have any children and is single valued; it would
3084 cost too much space to save so little time. */
3086 if (node->right->right || node->right->left
3087 || !tree_int_cst_equal (node->right->low, node->right->high))
3089 if (!node_has_low_bound (node, index_type))
3091 emit_cmp_and_jump_insns (index,
3092 convert_modes
3093 (mode, imode,
3094 expand_expr (node->high, NULL_RTX,
3095 VOIDmode, 0),
3096 unsignedp),
3097 LT, NULL_RTX, mode, unsignedp,
3098 default_label);
3101 emit_case_nodes (index, node->right, default_label, index_type);
3103 else
3104 /* We cannot process node->right normally
3105 since we haven't ruled out the numbers less than
3106 this node's value. So handle node->right explicitly. */
3107 do_jump_if_equal (index,
3108 convert_modes
3109 (mode, imode,
3110 expand_expr (node->right->low, NULL_RTX,
3111 VOIDmode, 0),
3112 unsignedp),
3113 label_rtx (node->right->code_label), unsignedp);
3116 else if (node->right == 0 && node->left != 0)
3118 /* Just one subtree, on the left. */
3119 if (node->left->left || node->left->right
3120 || !tree_int_cst_equal (node->left->low, node->left->high))
3122 if (!node_has_high_bound (node, index_type))
3124 emit_cmp_and_jump_insns (index,
3125 convert_modes
3126 (mode, imode,
3127 expand_expr (node->high, NULL_RTX,
3128 VOIDmode, 0),
3129 unsignedp),
3130 GT, NULL_RTX, mode, unsignedp,
3131 default_label);
3134 emit_case_nodes (index, node->left, default_label, index_type);
3136 else
3137 /* We cannot process node->left normally
3138 since we haven't ruled out the numbers less than
3139 this node's value. So handle node->left explicitly. */
3140 do_jump_if_equal (index,
3141 convert_modes
3142 (mode, imode,
3143 expand_expr (node->left->low, NULL_RTX,
3144 VOIDmode, 0),
3145 unsignedp),
3146 label_rtx (node->left->code_label), unsignedp);
3149 else
3151 /* Node is a range. These cases are very similar to those for a single
3152 value, except that we do not start by testing whether this node
3153 is the one to branch to. */
3155 if (node->right != 0 && node->left != 0)
3157 /* Node has subtrees on both sides.
3158 If the right-hand subtree is bounded,
3159 test for it first, since we can go straight there.
3160 Otherwise, we need to make a branch in the control structure,
3161 then handle the two subtrees. */
3162 tree test_label = 0;
3164 if (node_is_bounded (node->right, index_type))
3165 /* Right hand node is fully bounded so we can eliminate any
3166 testing and branch directly to the target code. */
3167 emit_cmp_and_jump_insns (index,
3168 convert_modes
3169 (mode, imode,
3170 expand_expr (node->high, NULL_RTX,
3171 VOIDmode, 0),
3172 unsignedp),
3173 GT, NULL_RTX, mode, unsignedp,
3174 label_rtx (node->right->code_label));
3175 else
3177 /* Right hand node requires testing.
3178 Branch to a label where we will handle it later. */
3180 test_label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
3181 emit_cmp_and_jump_insns (index,
3182 convert_modes
3183 (mode, imode,
3184 expand_expr (node->high, NULL_RTX,
3185 VOIDmode, 0),
3186 unsignedp),
3187 GT, NULL_RTX, mode, unsignedp,
3188 label_rtx (test_label));
3191 /* Value belongs to this node or to the left-hand subtree. */
3193 emit_cmp_and_jump_insns (index,
3194 convert_modes
3195 (mode, imode,
3196 expand_expr (node->low, NULL_RTX,
3197 VOIDmode, 0),
3198 unsignedp),
3199 GE, NULL_RTX, mode, unsignedp,
3200 label_rtx (node->code_label));
3202 /* Handle the left-hand subtree. */
3203 emit_case_nodes (index, node->left, default_label, index_type);
3205 /* If right node had to be handled later, do that now. */
3207 if (test_label)
3209 /* If the left-hand subtree fell through,
3210 don't let it fall into the right-hand subtree. */
3211 emit_jump (default_label);
3213 expand_label (test_label);
3214 emit_case_nodes (index, node->right, default_label, index_type);
3218 else if (node->right != 0 && node->left == 0)
3220 /* Deal with values to the left of this node,
3221 if they are possible. */
3222 if (!node_has_low_bound (node, index_type))
3224 emit_cmp_and_jump_insns (index,
3225 convert_modes
3226 (mode, imode,
3227 expand_expr (node->low, NULL_RTX,
3228 VOIDmode, 0),
3229 unsignedp),
3230 LT, NULL_RTX, mode, unsignedp,
3231 default_label);
3234 /* Value belongs to this node or to the right-hand subtree. */
3236 emit_cmp_and_jump_insns (index,
3237 convert_modes
3238 (mode, imode,
3239 expand_expr (node->high, NULL_RTX,
3240 VOIDmode, 0),
3241 unsignedp),
3242 LE, NULL_RTX, mode, unsignedp,
3243 label_rtx (node->code_label));
3245 emit_case_nodes (index, node->right, default_label, index_type);
3248 else if (node->right == 0 && node->left != 0)
3250 /* Deal with values to the right of this node,
3251 if they are possible. */
3252 if (!node_has_high_bound (node, index_type))
3254 emit_cmp_and_jump_insns (index,
3255 convert_modes
3256 (mode, imode,
3257 expand_expr (node->high, NULL_RTX,
3258 VOIDmode, 0),
3259 unsignedp),
3260 GT, NULL_RTX, mode, unsignedp,
3261 default_label);
3264 /* Value belongs to this node or to the left-hand subtree. */
3266 emit_cmp_and_jump_insns (index,
3267 convert_modes
3268 (mode, imode,
3269 expand_expr (node->low, NULL_RTX,
3270 VOIDmode, 0),
3271 unsignedp),
3272 GE, NULL_RTX, mode, unsignedp,
3273 label_rtx (node->code_label));
3275 emit_case_nodes (index, node->left, default_label, index_type);
3278 else
3280 /* Node has no children so we check low and high bounds to remove
3281 redundant tests. Only one of the bounds can exist,
3282 since otherwise this node is bounded--a case tested already. */
3283 int high_bound = node_has_high_bound (node, index_type);
3284 int low_bound = node_has_low_bound (node, index_type);
3286 if (!high_bound && low_bound)
3288 emit_cmp_and_jump_insns (index,
3289 convert_modes
3290 (mode, imode,
3291 expand_expr (node->high, NULL_RTX,
3292 VOIDmode, 0),
3293 unsignedp),
3294 GT, NULL_RTX, mode, unsignedp,
3295 default_label);
3298 else if (!low_bound && high_bound)
3300 emit_cmp_and_jump_insns (index,
3301 convert_modes
3302 (mode, imode,
3303 expand_expr (node->low, NULL_RTX,
3304 VOIDmode, 0),
3305 unsignedp),
3306 LT, NULL_RTX, mode, unsignedp,
3307 default_label);
3309 else if (!low_bound && !high_bound)
3311 /* Widen LOW and HIGH to the same width as INDEX. */
3312 tree type = lang_hooks.types.type_for_mode (mode, unsignedp);
3313 tree low = build1 (CONVERT_EXPR, type, node->low);
3314 tree high = build1 (CONVERT_EXPR, type, node->high);
3315 rtx low_rtx, new_index, new_bound;
3317 /* Instead of doing two branches, emit one unsigned branch for
3318 (index-low) > (high-low). */
3319 low_rtx = expand_expr (low, NULL_RTX, mode, 0);
3320 new_index = expand_simple_binop (mode, MINUS, index, low_rtx,
3321 NULL_RTX, unsignedp,
3322 OPTAB_WIDEN);
3323 new_bound = expand_expr (fold_build2 (MINUS_EXPR, type,
3324 high, low),
3325 NULL_RTX, mode, 0);
3327 emit_cmp_and_jump_insns (new_index, new_bound, GT, NULL_RTX,
3328 mode, 1, default_label);
3331 emit_jump (label_rtx (node->code_label));