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.
5
6 This file is part of GCC.
7
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.
12
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.
17
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. */
22
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. */
27
28 #include "config.h"
29 #include "system.h"
30 #include "coretypes.h"
31 #include "tm.h"
32
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"
53
54 /* Functions and data structures for expanding case statements. */
55
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.
59
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.
65
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.
71
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.
79
80 For very small, suitable switch statements, we can generate a series
81 of simple bit test and branches instead. */
82
83 struct case_node GTY(())
84 {
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 */
91 };
92
93 typedef struct case_node case_node;
94 typedef struct case_node *case_node_ptr;
95
96 /* These are used by estimate_case_costs and balance_case_nodes. */
97
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;
102
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)]
106
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);
127
128
129 /* Return the rtx-label that corresponds to a LABEL_DECL,
130 creating it if necessary. */
131
132 rtx
label_rtx(tree label)133 label_rtx (tree label)
134 {
135 gcc_assert (TREE_CODE (label) == LABEL_DECL);
136
137 if (!DECL_RTL_SET_P (label))
138 {
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;
143 }
144
145 return DECL_RTL (label);
146 }
147
148 /* As above, but also put it on the forced-reference list of the
149 function that contains it. */
150 rtx
force_label_rtx(tree label)151 force_label_rtx (tree label)
152 {
153 rtx ref = label_rtx (label);
154 tree function = decl_function_context (label);
155 struct function *p;
156
157 gcc_assert (function);
158
159 if (function != current_function_decl)
160 p = find_function_data (function);
161 else
162 p = cfun;
163
164 p->expr->x_forced_labels = gen_rtx_EXPR_LIST (VOIDmode, ref,
165 p->expr->x_forced_labels);
166 return ref;
167 }
168
169 /* Add an unconditional jump to LABEL as the next sequential instruction. */
170
171 void
emit_jump(rtx label)172 emit_jump (rtx label)
173 {
174 do_pending_stack_adjust ();
175 emit_jump_insn (gen_jump (label));
176 emit_barrier ();
177 }
178
179 /* Emit code to jump to the address
180 specified by the pointer expression EXP. */
181
182 void
expand_computed_goto(tree exp)183 expand_computed_goto (tree exp)
184 {
185 rtx x = expand_expr (exp, NULL_RTX, VOIDmode, 0);
186
187 x = convert_memory_address (Pmode, x);
188
189 do_pending_stack_adjust ();
190 emit_indirect_jump (x);
191 }
192
193 /* Handle goto statements and the labels that they can go to. */
194
195 /* Specify the location in the RTL code of a label LABEL,
196 which is a LABEL_DECL tree node.
197
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.
202
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. */
205
206 void
expand_label(tree label)207 expand_label (tree label)
208 {
209 rtx label_r = label_rtx (label);
210
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));
215
216 if (DECL_NONLOCAL (label))
217 {
218 expand_nl_goto_receiver ();
219 nonlocal_goto_handler_labels
220 = gen_rtx_EXPR_LIST (VOIDmode, label_r,
221 nonlocal_goto_handler_labels);
222 }
223
224 if (FORCED_LABEL (label))
225 forced_labels = gen_rtx_EXPR_LIST (VOIDmode, label_r, forced_labels);
226
227 if (DECL_NONLOCAL (label) || FORCED_LABEL (label))
228 maybe_set_first_label_num (label_r);
229 }
230
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'. */
234
235 void
expand_goto(tree label)236 expand_goto (tree label)
237 {
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
244
245 emit_jump (label_rtx (label));
246 }
247
248 /* Return the number of times character C occurs in string S. */
249 static int
n_occurrences(int c,const char * s)250 n_occurrences (int c, const char *s)
251 {
252 int n = 0;
253 while (*s)
254 n += (*s++ == c);
255 return n;
256 }
257
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. */
262
263 static void
expand_asm(tree string,int vol)264 expand_asm (tree string, int vol)
265 {
266 rtx body;
267
268 if (TREE_CODE (string) == ADDR_EXPR)
269 string = TREE_OPERAND (string, 0);
270
271 body = gen_rtx_ASM_INPUT (VOIDmode,
272 ggc_strdup (TREE_STRING_POINTER (string)));
273
274 MEM_VOLATILE_P (body) = vol;
275
276 emit_insn (body);
277 }
278
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.)
289
290 Returns TRUE if all went well; FALSE if an error occurred. */
291
292 bool
parse_output_constraint(const char ** constraint_p,int operand_num,int ninputs,int noutputs,bool * allows_mem,bool * allows_reg,bool * is_inout)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)
296 {
297 const char *constraint = *constraint_p;
298 const char *p;
299
300 /* Assume the constraint doesn't allow the use of either a register
301 or memory. */
302 *allows_mem = false;
303 *allows_reg = false;
304
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, '+');
312
313 /* If the string doesn't contain an `=', issue an error
314 message. */
315 if (!p)
316 {
317 error ("output operand constraint lacks %<=%>");
318 return false;
319 }
320
321 /* If the constraint begins with `+', then the operand is both read
322 from and written to. */
323 *is_inout = (*p == '+');
324
325 /* Canonicalize the output constraint so that it begins with `='. */
326 if (p != constraint || *is_inout)
327 {
328 char *buf;
329 size_t c_len = strlen (constraint);
330
331 if (p != constraint)
332 warning (0, "output constraint %qc for operand %d "
333 "is not at the beginning",
334 *p, operand_num);
335
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;
347 }
348
349 /* Loop through the constraint string. */
350 for (p = constraint + 1; *p; p += CONSTRAINT_LEN (*p, p))
351 switch (*p)
352 {
353 case '+':
354 case '=':
355 error ("operand constraint contains incorrectly positioned "
356 "%<+%> or %<=%>");
357 return false;
358
359 case '%':
360 if (operand_num + 1 == ninputs + noutputs)
361 {
362 error ("%<%%%> constraint used with last operand");
363 return false;
364 }
365 break;
366
367 case 'V': case 'm': case 'o':
368 *allows_mem = true;
369 break;
370
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;
377
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;
383
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;
390
391 case 'g': case 'X':
392 *allows_reg = true;
393 *allows_mem = true;
394 break;
395
396 case 'p': case 'r':
397 *allows_reg = true;
398 break;
399
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
411 {
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;
417 }
418 #endif
419 break;
420 }
421
422 return true;
423 }
424
425 /* Similar, but for input constraints. */
426
427 bool
parse_input_constraint(const char ** constraint_p,int input_num,int ninputs,int noutputs,int ninout,const char * const * constraints,bool * allows_mem,bool * allows_reg)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)
432 {
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;
438
439 /* Assume the constraint doesn't allow the use of either
440 a register or memory. */
441 *allows_mem = false;
442 *allows_reg = false;
443
444 /* Make sure constraint has neither `=', `+', nor '&'. */
445
446 for (j = 0; j < c_len; j += CONSTRAINT_LEN (constraint[j], constraint+j))
447 switch (constraint[j])
448 {
449 case '+': case '=': case '&':
450 if (constraint == orig_constraint)
451 {
452 error ("input operand constraint contains %qc", constraint[j]);
453 return false;
454 }
455 break;
456
457 case '%':
458 if (constraint == orig_constraint
459 && input_num + 1 == ninputs - ninout)
460 {
461 error ("%<%%%> constraint used with last operand");
462 return false;
463 }
464 break;
465
466 case 'V': case 'm': case 'o':
467 *allows_mem = true;
468 break;
469
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;
477
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':
485 {
486 char *end;
487 unsigned long match;
488
489 saw_match = true;
490
491 match = strtoul (constraint + j, &end, 10);
492 if (match >= (unsigned long) noutputs)
493 {
494 error ("matching constraint references invalid operand number");
495 return false;
496 }
497
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] == '%')))
502 {
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;
512 }
513 else
514 j = end - constraint;
515 /* Anticipate increment at end of loop. */
516 j--;
517 }
518 /* Fall through. */
519
520 case 'p': case 'r':
521 *allows_reg = true;
522 break;
523
524 case 'g': case 'X':
525 *allows_reg = true;
526 *allows_mem = true;
527 break;
528
529 default:
530 if (! ISALPHA (constraint[j]))
531 {
532 error ("invalid punctuation %qc in constraint", constraint[j]);
533 return false;
534 }
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
544 {
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;
550 }
551 #endif
552 break;
553 }
554
555 if (saw_match && !*allows_reg)
556 warning (0, "matching constraint does not allow a register");
557
558 return true;
559 }
560
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. */
563
564 static tree
decl_overlaps_hard_reg_set_p(tree * declp,int * walk_subtrees ATTRIBUTE_UNUSED,void * data)565 decl_overlaps_hard_reg_set_p (tree *declp, int *walk_subtrees ATTRIBUTE_UNUSED,
566 void *data)
567 {
568 tree decl = *declp;
569 const HARD_REG_SET *regs = data;
570
571 if (TREE_CODE (decl) == VAR_DECL)
572 {
573 if (DECL_HARD_REGISTER (decl)
574 && REG_P (DECL_RTL (decl))
575 && REGNO (DECL_RTL (decl)) < FIRST_PSEUDO_REGISTER)
576 {
577 rtx reg = DECL_RTL (decl);
578 unsigned int regno;
579
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;
586 }
587 walk_subtrees = 0;
588 }
589 else if (TYPE_P (decl) || TREE_CODE (decl) == PARM_DECL)
590 walk_subtrees = 0;
591 return NULL_TREE;
592 }
593
594 /* If there is an overlap between *REGS and DECL, return the first overlap
595 found. */
596 tree
tree_overlaps_hard_reg_set(tree decl,HARD_REG_SET * regs)597 tree_overlaps_hard_reg_set (tree decl, HARD_REG_SET *regs)
598 {
599 return walk_tree (&decl, decl_overlaps_hard_reg_set_p, regs, NULL);
600 }
601
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. */
605
606 static bool
tree_conflicts_with_clobbers_p(tree t,HARD_REG_SET * clobbered_regs)607 tree_conflicts_with_clobbers_p (tree t, HARD_REG_SET *clobbered_regs)
608 {
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);
612
613 if (overlap)
614 {
615 error ("asm-specifier for variable %qs conflicts with asm clobber list",
616 IDENTIFIER_POINTER (DECL_NAME (overlap)));
617
618 /* Reset registerness to stop multiple errors emitted for a single
619 variable. */
620 DECL_REGISTER (overlap) = 0;
621 return true;
622 }
623
624 return false;
625 }
626
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.
636
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.
641
642 VOL nonzero means the insn is volatile; don't optimize it. */
643
644 static void
expand_asm_operands(tree string,tree outputs,tree inputs,tree clobbers,int vol,location_t locus)645 expand_asm_operands (tree string, tree outputs, tree inputs,
646 tree clobbers, int vol, location_t locus)
647 {
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;
668
669 /* An ASM with no outputs needs to be treated as volatile, for now. */
670 if (noutputs == 0)
671 vol = 1;
672
673 if (! check_operand_nalternatives (outputs, inputs))
674 return;
675
676 string = resolve_asm_operand_names (string, outputs, inputs);
677
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)));
684
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);
690
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))
696 {
697 const char *regname;
698
699 if (TREE_VALUE (tail) == error_mark_node)
700 return;
701 regname = TREE_STRING_POINTER (TREE_VALUE (tail));
702
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);
708
709 /* Mark clobbered registers. */
710 if (i >= 0)
711 {
712 /* Clobbering the PIC register is an error. */
713 if (i == (int) PIC_OFFSET_TABLE_REGNUM)
714 {
715 error ("PIC register %qs clobbered in %<asm%>", regname);
716 return;
717 }
718
719 SET_HARD_REG_BIT (clobbered_regs, i);
720 }
721 }
722
723 /* First pass over inputs and outputs checks validity and sets
724 mark_addressable if needed. */
725
726 ninout = 0;
727 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
728 {
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;
735
736 /* If there's an erroneous arg, emit no insn. */
737 if (type == error_mark_node)
738 return;
739
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;
746
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);
754
755 if (is_inout)
756 ninout++;
757 }
758
759 ninputs += ninout;
760 if (ninputs + noutputs > MAX_RECOG_OPERANDS)
761 {
762 error ("more than %d operands in %<asm%>", MAX_RECOG_OPERANDS);
763 return;
764 }
765
766 for (i = 0, tail = inputs; tail; i++, tail = TREE_CHAIN (tail))
767 {
768 bool allows_reg, allows_mem;
769 const char *constraint;
770
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;
775
776 constraint = constraints[i + noutputs];
777 if (! parse_input_constraint (&constraint, i, ninputs, noutputs, ninout,
778 constraints, &allows_mem, &allows_reg))
779 return;
780
781 if (! allows_reg && allows_mem)
782 lang_hooks.mark_addressable (TREE_VALUE (tail));
783 }
784
785 /* Second pass evaluates arguments. */
786
787 ninout = 0;
788 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
789 {
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;
797
798 ok = parse_output_constraint (&constraints[i], i, ninputs,
799 noutputs, &allows_mem, &allows_reg,
800 &is_inout);
801 gcc_assert (ok);
802
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. */
807
808 generating_concat_p = 0;
809
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)
819 {
820 op = expand_expr (val, NULL_RTX, VOIDmode, EXPAND_WRITE);
821 if (MEM_P (op))
822 op = validize_mem (op);
823
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)
828 {
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]);
833 }
834 }
835 else
836 {
837 op = assign_temp (type, 0, 0, 1);
838 op = validize_mem (op);
839 TREE_VALUE (tail) = make_tree (type, op);
840 }
841 output_rtx[i] = op;
842
843 generating_concat_p = old_generating_concat_p;
844
845 if (is_inout)
846 {
847 inout_mode[ninout] = TYPE_MODE (type);
848 inout_opnum[ninout++] = i;
849 }
850
851 if (tree_conflicts_with_clobbers_p (val, &clobbered_regs))
852 clobber_conflict_found = 1;
853 }
854
855 /* Make vectors for the expression-rtx, constraint strings,
856 and named operands. */
857
858 argvec = rtvec_alloc (ninputs);
859 constraintvec = rtvec_alloc (ninputs);
860
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);
866
867 MEM_VOLATILE_P (body) = vol;
868
869 /* Eval the inputs and put them into ARGVEC.
870 Put their constraints into ASM_INPUTs and store in CONSTRAINTS. */
871
872 for (i = 0, tail = inputs; tail; tail = TREE_CHAIN (tail), ++i)
873 {
874 bool allows_reg, allows_mem;
875 const char *constraint;
876 tree val, type;
877 rtx op;
878 bool ok;
879
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);
884
885 generating_concat_p = 0;
886
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));
892
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);
898
899 if (asm_operand_ok (op, constraint) <= 0)
900 {
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))
907 {
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. */
911 }
912 else
913 {
914 warning (0, "use of memory input without lvalue in "
915 "asm operand %d is deprecated", i + noutputs);
916
917 if (CONSTANT_P (op))
918 {
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);
924 }
925 if (REG_P (op)
926 || GET_CODE (op) == SUBREG
927 || GET_CODE (op) == CONCAT)
928 {
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;
936 }
937 }
938 }
939
940 generating_concat_p = old_generating_concat_p;
941 ASM_OPERANDS_INPUT (body, i) = op;
942
943 ASM_OPERANDS_INPUT_CONSTRAINT_EXP (body, i)
944 = gen_rtx_ASM_INPUT (TYPE_MODE (type),
945 ggc_strdup (constraints[i + noutputs]));
946
947 if (tree_conflicts_with_clobbers_p (val, &clobbered_regs))
948 clobber_conflict_found = 1;
949 }
950
951 /* Protect all the operands from the queue now that they have all been
952 evaluated. */
953
954 generating_concat_p = 0;
955
956 /* For in-out operands, copy output rtx to input rtx. */
957 for (i = 0; i < ninout; i++)
958 {
959 int j = inout_opnum[i];
960 char buffer[16];
961
962 ASM_OPERANDS_INPUT (body, ninputs - ninout + i)
963 = output_rtx[j];
964
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));
968 }
969
970 generating_concat_p = old_generating_concat_p;
971
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. */
976
977 if (noutputs == 1 && nclobbers == 0)
978 {
979 ASM_OPERANDS_OUTPUT_CONSTRAINT (body) = ggc_strdup (constraints[0]);
980 emit_insn (gen_rtx_SET (VOIDmode, output_rtx[0], body));
981 }
982
983 else if (noutputs == 0 && nclobbers == 0)
984 {
985 /* No output operands: put in a raw ASM_OPERANDS rtx. */
986 emit_insn (body);
987 }
988
989 else
990 {
991 rtx obody = body;
992 int num = noutputs;
993
994 if (num == 0)
995 num = 1;
996
997 body = gen_rtx_PARALLEL (VOIDmode, rtvec_alloc (num + nclobbers));
998
999 /* For each output operand, store a SET. */
1000 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
1001 {
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));
1010
1011 MEM_VOLATILE_P (SET_SRC (XVECEXP (body, 0, i))) = vol;
1012 }
1013
1014 /* If there are no outputs (but there are some clobbers)
1015 store the bare ASM_OPERANDS into the PARALLEL. */
1016
1017 if (i == 0)
1018 XVECEXP (body, 0, i++) = obody;
1019
1020 /* Store (clobber REG) for each clobbered register specified. */
1021
1022 for (tail = clobbers; tail; tail = TREE_CHAIN (tail))
1023 {
1024 const char *regname = TREE_STRING_POINTER (TREE_VALUE (tail));
1025 int j = decode_reg_name (regname);
1026 rtx clobbered_reg;
1027
1028 if (j < 0)
1029 {
1030 if (j == -3) /* `cc', which is not a register */
1031 continue;
1032
1033 if (j == -4) /* `memory', don't cache memory across asm */
1034 {
1035 XVECEXP (body, 0, i++)
1036 = gen_rtx_CLOBBER (VOIDmode,
1037 gen_rtx_MEM
1038 (BLKmode,
1039 gen_rtx_SCRATCH (VOIDmode)));
1040 continue;
1041 }
1042
1043 /* Ignore unknown register, error already signaled. */
1044 continue;
1045 }
1046
1047 /* Use QImode since that's guaranteed to clobber just one reg. */
1048 clobbered_reg = gen_rtx_REG (QImode, j);
1049
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)
1054 {
1055 int opno;
1056
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");
1062
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");
1067 }
1068
1069 XVECEXP (body, 0, i++)
1070 = gen_rtx_CLOBBER (VOIDmode, clobbered_reg);
1071 }
1072
1073 emit_insn (body);
1074 }
1075
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]);
1081
1082 free_temp_slots ();
1083 }
1084
1085 void
expand_asm_expr(tree exp)1086 expand_asm_expr (tree exp)
1087 {
1088 int noutputs, i;
1089 tree outputs, tail;
1090 tree *o;
1091
1092 if (ASM_INPUT_P (exp))
1093 {
1094 expand_asm (ASM_STRING (exp), ASM_VOLATILE_P (exp));
1095 return;
1096 }
1097
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));
1102
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);
1106
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);
1112
1113 /* Copy all the intermediate outputs into the specified outputs. */
1114 for (i = 0, tail = outputs; tail; tail = TREE_CHAIN (tail), i++)
1115 {
1116 if (o[i] != TREE_VALUE (tail))
1117 {
1118 expand_assignment (o[i], TREE_VALUE (tail));
1119 free_temp_slots ();
1120
1121 /* Restore the original value so that it's correct the next
1122 time we expand this function. */
1123 TREE_VALUE (tail) = o[i];
1124 }
1125 }
1126 }
1127
1128 /* A subroutine of expand_asm_operands. Check that all operands have
1129 the same number of alternatives. Return true if so. */
1130
1131 static bool
check_operand_nalternatives(tree outputs,tree inputs)1132 check_operand_nalternatives (tree outputs, tree inputs)
1133 {
1134 if (outputs || inputs)
1135 {
1136 tree tmp = TREE_PURPOSE (outputs ? outputs : inputs);
1137 int nalternatives
1138 = n_occurrences (',', TREE_STRING_POINTER (TREE_VALUE (tmp)));
1139 tree next = inputs;
1140
1141 if (nalternatives + 1 > MAX_RECOG_ALTERNATIVES)
1142 {
1143 error ("too many alternatives in %<asm%>");
1144 return false;
1145 }
1146
1147 tmp = outputs;
1148 while (tmp)
1149 {
1150 const char *constraint
1151 = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (tmp)));
1152
1153 if (n_occurrences (',', constraint) != nalternatives)
1154 {
1155 error ("operand constraints for %<asm%> differ "
1156 "in number of alternatives");
1157 return false;
1158 }
1159
1160 if (TREE_CHAIN (tmp))
1161 tmp = TREE_CHAIN (tmp);
1162 else
1163 tmp = next, next = 0;
1164 }
1165 }
1166
1167 return true;
1168 }
1169
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. */
1174
1175 static bool
check_unique_operand_names(tree outputs,tree inputs)1176 check_unique_operand_names (tree outputs, tree inputs)
1177 {
1178 tree i, j;
1179
1180 for (i = outputs; i ; i = TREE_CHAIN (i))
1181 {
1182 tree i_name = TREE_PURPOSE (TREE_PURPOSE (i));
1183 if (! i_name)
1184 continue;
1185
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;
1189 }
1190
1191 for (i = inputs; i ; i = TREE_CHAIN (i))
1192 {
1193 tree i_name = TREE_PURPOSE (TREE_PURPOSE (i));
1194 if (! i_name)
1195 continue;
1196
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;
1203 }
1204
1205 return true;
1206
1207 failure:
1208 error ("duplicate asm operand name %qs",
1209 TREE_STRING_POINTER (TREE_PURPOSE (TREE_PURPOSE (i))));
1210 return false;
1211 }
1212
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. */
1216
1217 tree
resolve_asm_operand_names(tree string,tree outputs,tree inputs)1218 resolve_asm_operand_names (tree string, tree outputs, tree inputs)
1219 {
1220 char *buffer;
1221 char *p;
1222 const char *c;
1223 tree t;
1224
1225 check_unique_operand_names (outputs, inputs);
1226
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))
1230 {
1231 c = TREE_STRING_POINTER (TREE_VALUE (TREE_PURPOSE (t)));
1232 if (strchr (c, '[') != NULL)
1233 {
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);
1240 }
1241 }
1242
1243 /* Now check for any needed substitutions in the template. */
1244 c = TREE_STRING_POINTER (string);
1245 while ((c = strchr (c, '%')) != NULL)
1246 {
1247 if (c[1] == '[')
1248 break;
1249 else if (ISALPHA (c[1]) && c[2] == '[')
1250 break;
1251 else
1252 {
1253 c += 1;
1254 continue;
1255 }
1256 }
1257
1258 if (c)
1259 {
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));
1266
1267 while ((p = strchr (p, '%')) != NULL)
1268 {
1269 if (p[1] == '[')
1270 p += 1;
1271 else if (ISALPHA (p[1]) && p[2] == '[')
1272 p += 2;
1273 else
1274 {
1275 p += 1;
1276 continue;
1277 }
1278
1279 p = resolve_operand_name_1 (p, outputs, inputs);
1280 }
1281
1282 string = build_string (strlen (buffer), buffer);
1283 free (buffer);
1284 }
1285
1286 return string;
1287 }
1288
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. */
1293
1294 static char *
resolve_operand_name_1(char * p,tree outputs,tree inputs)1295 resolve_operand_name_1 (char *p, tree outputs, tree inputs)
1296 {
1297 char *q;
1298 int op;
1299 tree t;
1300 size_t len;
1301
1302 /* Collect the operand name. */
1303 q = strchr (p, ']');
1304 if (!q)
1305 {
1306 error ("missing close brace for named operand");
1307 return strchr (p, '\0');
1308 }
1309 len = q - p - 1;
1310
1311 /* Resolve the name to a number. */
1312 for (op = 0, t = outputs; t ; t = TREE_CHAIN (t), op++)
1313 {
1314 tree name = TREE_PURPOSE (TREE_PURPOSE (t));
1315 if (name)
1316 {
1317 const char *c = TREE_STRING_POINTER (name);
1318 if (strncmp (c, p + 1, len) == 0 && c[len] == '\0')
1319 goto found;
1320 }
1321 }
1322 for (t = inputs; t ; t = TREE_CHAIN (t), op++)
1323 {
1324 tree name = TREE_PURPOSE (TREE_PURPOSE (t));
1325 if (name)
1326 {
1327 const char *c = TREE_STRING_POINTER (name);
1328 if (strncmp (c, p + 1, len) == 0 && c[len] == '\0')
1329 goto found;
1330 }
1331 }
1332
1333 *q = '\0';
1334 error ("undefined named operand %qs", p + 1);
1335 op = 0;
1336 found:
1337
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');
1343
1344 /* Verify the no extra buffer space assumption. */
1345 gcc_assert (p <= q);
1346
1347 /* Shift the rest of the buffer down to fill the gap. */
1348 memmove (p, q + 1, strlen (q + 1) + 1);
1349
1350 return p;
1351 }
1352
1353 /* Generate RTL to evaluate the expression EXP. */
1354
1355 void
expand_expr_stmt(tree exp)1356 expand_expr_stmt (tree exp)
1357 {
1358 rtx value;
1359 tree type;
1360
1361 value = expand_expr (exp, const0_rtx, VOIDmode, 0);
1362 type = TREE_TYPE (exp);
1363
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))
1367 {
1368 if (TYPE_MODE (type) == VOIDmode)
1369 ;
1370 else if (TYPE_MODE (type) != BLKmode)
1371 value = copy_to_reg (value);
1372 else
1373 {
1374 rtx lab = gen_label_rtx ();
1375
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);
1382 }
1383 }
1384
1385 /* Free any temporaries used to evaluate this expression. */
1386 free_temp_slots ();
1387 }
1388
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. */
1392
1393 int
warn_if_unused_value(tree exp,location_t locus)1394 warn_if_unused_value (tree exp, location_t locus)
1395 {
1396 restart:
1397 if (TREE_USED (exp) || TREE_NO_WARNING (exp))
1398 return 0;
1399
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;
1405
1406 if (EXPR_HAS_LOCATION (exp))
1407 locus = EXPR_LOCATION (exp);
1408
1409 switch (TREE_CODE (exp))
1410 {
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;
1423
1424 case BIND_EXPR:
1425 /* For a binding, warn if no side effect within it. */
1426 exp = BIND_EXPR_BODY (exp);
1427 goto restart;
1428
1429 case SAVE_EXPR:
1430 exp = TREE_OPERAND (exp, 0);
1431 goto restart;
1432
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;
1438
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;
1447
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;
1454
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)
1459 {
1460 exp = TREE_OPERAND (exp, 0);
1461 goto restart;
1462 }
1463 /* Fall through. */
1464
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;
1470
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;
1476
1477 warn:
1478 warning (0, "%Hvalue computed is not used", &locus);
1479 return 1;
1480 }
1481 }
1482
1483
1484 /* Generate RTL to return from the current function, with no value.
1485 (That is, we do not do anything about returning any value.) */
1486
1487 void
expand_null_return(void)1488 expand_null_return (void)
1489 {
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 ();
1494
1495 expand_null_return_1 ();
1496 }
1497
1498 /* Generate RTL to return directly from the current function.
1499 (That is, we bypass any return value.) */
1500
1501 void
expand_naked_return(void)1502 expand_naked_return (void)
1503 {
1504 rtx end_label;
1505
1506 clear_pending_stack_adjust ();
1507 do_pending_stack_adjust ();
1508
1509 end_label = naked_return_label;
1510 if (end_label == 0)
1511 end_label = naked_return_label = gen_label_rtx ();
1512
1513 emit_jump (end_label);
1514 }
1515
1516 /* Generate RTL to return from the current function, with value VAL. */
1517
1518 static void
expand_value_return(rtx val)1519 expand_value_return (rtx val)
1520 {
1521 /* Copy the value to the return location
1522 unless it's already there. */
1523
1524 rtx return_reg = DECL_RTL (DECL_RESULT (current_function_decl));
1525 if (return_reg != val)
1526 {
1527 tree type = TREE_TYPE (DECL_RESULT (current_function_decl));
1528 if (targetm.calls.promote_function_return (TREE_TYPE (current_function_decl)))
1529 {
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);
1535
1536 if (mode != old_mode)
1537 val = convert_modes (mode, old_mode, val, unsignedp);
1538 }
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);
1543 }
1544
1545 expand_null_return_1 ();
1546 }
1547
1548 /* Output a return with no value. */
1549
1550 static void
expand_null_return_1(void)1551 expand_null_return_1 (void)
1552 {
1553 clear_pending_stack_adjust ();
1554 do_pending_stack_adjust ();
1555 emit_jump (return_label);
1556 }
1557
1558 /* Generate RTL to evaluate the expression RETVAL and return it
1559 from the current function. */
1560
1561 void
expand_return(tree retval)1562 expand_return (tree retval)
1563 {
1564 rtx result_rtl;
1565 rtx val = 0;
1566 tree retval_rhs;
1567
1568 /* If function wants no value, give it none. */
1569 if (TREE_CODE (TREE_TYPE (TREE_TYPE (current_function_decl))) == VOID_TYPE)
1570 {
1571 expand_expr (retval, NULL_RTX, VOIDmode, 0);
1572 expand_null_return ();
1573 return;
1574 }
1575
1576 if (retval == error_mark_node)
1577 {
1578 /* Treat this like a return of no value from a function that
1579 returns a value. */
1580 expand_null_return ();
1581 return;
1582 }
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;
1589
1590 result_rtl = DECL_RTL (DECL_RESULT (current_function_decl));
1591
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);
1596
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). */
1603
1604 else if (retval_rhs != 0
1605 && TYPE_MODE (TREE_TYPE (retval_rhs)) == BLKmode
1606 && REG_P (result_rtl))
1607 {
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;
1620
1621 if (bytes == 0)
1622 {
1623 expand_null_return ();
1624 return;
1625 }
1626
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.
1631
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));
1643
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)
1648 {
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)
1654 {
1655 /* Generate an appropriate register. */
1656 dst = gen_reg_rtx (word_mode);
1657 result_pseudos[xbitpos / BITS_PER_WORD] = dst;
1658
1659 /* Clear the destination before we move anything into it. */
1660 emit_move_insn (dst, CONST0_RTX (GET_MODE (dst)));
1661 }
1662
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);
1669
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));
1676 }
1677
1678 tmpmode = GET_MODE (result_rtl);
1679 if (tmpmode == BLKmode)
1680 {
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;
1690
1691 /* A suitable mode should have been found. */
1692 gcc_assert (tmpmode != VOIDmode);
1693
1694 PUT_MODE (result_rtl, tmpmode);
1695 }
1696
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);
1702
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]);
1706
1707 if (tmpmode != result_reg_mode)
1708 result_reg = gen_lowpart (tmpmode, result_reg);
1709
1710 expand_value_return (result_reg);
1711 }
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)))
1716 {
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);
1721
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);
1727 }
1728 else
1729 {
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);
1733 }
1734 }
1735
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.
1739
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. */
1745
1746 int
is_body_block(tree stmt)1747 is_body_block (tree stmt)
1748 {
1749 if (lang_hooks.no_body_blocks)
1750 return 0;
1751
1752 if (TREE_CODE (stmt) == BLOCK)
1753 {
1754 tree parent = BLOCK_SUPERCONTEXT (stmt);
1755
1756 if (parent && TREE_CODE (parent) == BLOCK)
1757 {
1758 tree grandparent = BLOCK_SUPERCONTEXT (parent);
1759
1760 if (grandparent && TREE_CODE (grandparent) == FUNCTION_DECL)
1761 return 1;
1762 }
1763 }
1764
1765 return 0;
1766 }
1767
1768 /* Emit code to restore vital registers at the beginning of a nonlocal goto
1769 handler. */
1770 static void
expand_nl_goto_receiver(void)1771 expand_nl_goto_receiver (void)
1772 {
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));
1776
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));
1780
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.
1788
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);
1796
1797 #if ARG_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
1798 if (fixed_regs[ARG_POINTER_REGNUM])
1799 {
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;
1808
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;
1813
1814 if (i == ARRAY_SIZE (elim_regs))
1815 #endif
1816 {
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)));
1821 }
1822 }
1823 #endif
1824
1825 #ifdef HAVE_nonlocal_goto_receiver
1826 if (HAVE_nonlocal_goto_receiver)
1827 emit_insn (gen_nonlocal_goto_receiver ());
1828 #endif
1829
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, ""));
1836 }
1837
1838 /* Generate RTL for the automatic variable declaration DECL.
1839 (Other kinds of declarations are simply ignored if seen here.) */
1840
1841 void
expand_decl(tree decl)1842 expand_decl (tree decl)
1843 {
1844 tree type;
1845
1846 type = TREE_TYPE (decl);
1847
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)
1851 {
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;
1857 }
1858
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;
1865
1866 if (TREE_STATIC (decl) || DECL_EXTERNAL (decl))
1867 return;
1868
1869 /* Create the RTL representation for the variable. */
1870
1871 if (type == error_mark_node)
1872 SET_DECL_RTL (decl, gen_rtx_MEM (BLKmode, const0_rtx));
1873
1874 else if (DECL_SIZE (decl) == 0)
1875 /* Variable with incomplete type. */
1876 {
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));
1885
1886 set_mem_attributes (x, decl, 1);
1887 SET_DECL_RTL (decl, x);
1888 }
1889 else if (use_register_for_decl (decl))
1890 {
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);
1895
1896 SET_DECL_RTL (decl, gen_reg_rtx (reg_mode));
1897
1898 /* Note if the object is a user variable. */
1899 if (!DECL_ARTIFICIAL (decl))
1900 {
1901 mark_user_reg (DECL_RTL (decl));
1902
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))));
1912 }
1913 }
1914
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)))
1919 {
1920 /* Variable of fixed size that goes on the stack. */
1921 rtx oldaddr = 0;
1922 rtx addr;
1923 rtx x;
1924
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))
1930 {
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);
1934 }
1935
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;
1940
1941 x = assign_temp (decl, 1, 1, 1);
1942 set_mem_attributes (x, decl, 1);
1943 SET_DECL_RTL (decl, x);
1944
1945 if (oldaddr)
1946 {
1947 addr = force_operand (XEXP (DECL_RTL (decl), 0), oldaddr);
1948 if (addr != oldaddr)
1949 emit_move_insn (oldaddr, addr);
1950 }
1951 }
1952 else
1953 /* Dynamic-size object: must push space on the stack. */
1954 {
1955 rtx address, size, x;
1956
1957 /* Record the stack pointer on entry to block, if have
1958 not already done so. */
1959 do_pending_stack_adjust ();
1960
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 ();
1965
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)));
1972
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);
1977
1978
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;
1986 }
1987 }
1988
1989 /* Emit code to save the current value of stack. */
1990 rtx
expand_stack_save(void)1991 expand_stack_save (void)
1992 {
1993 rtx ret = NULL_RTX;
1994
1995 do_pending_stack_adjust ();
1996 emit_stack_save (SAVE_BLOCK, &ret, NULL_RTX);
1997 return ret;
1998 }
1999
2000 /* Emit code to restore the current value of stack. */
2001 void
expand_stack_restore(tree var)2002 expand_stack_restore (tree var)
2003 {
2004 rtx sa = DECL_RTL (var);
2005
2006 emit_stack_restore (SAVE_BLOCK, sa, NULL_RTX);
2007 }
2008
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. */
2012
2013 void
expand_anon_union_decl(tree decl,tree cleanup ATTRIBUTE_UNUSED,tree decl_elts)2014 expand_anon_union_decl (tree decl, tree cleanup ATTRIBUTE_UNUSED,
2015 tree decl_elts)
2016 {
2017 rtx x;
2018 tree t;
2019
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)))
2023 {
2024 TREE_ADDRESSABLE (decl) = 1;
2025 break;
2026 }
2027
2028 expand_decl (decl);
2029 x = DECL_RTL (decl);
2030
2031 /* Go through the elements, assigning RTL to each. */
2032 for (t = decl_elts; t; t = TREE_CHAIN (t))
2033 {
2034 tree decl_elt = TREE_VALUE (t);
2035 enum machine_mode mode = TYPE_MODE (TREE_TYPE (decl_elt));
2036 rtx decl_rtl;
2037
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;
2042
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);
2046
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);
2053
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
2061 {
2062 gcc_assert (REG_P (x));
2063 decl_rtl = gen_lowpart_SUBREG (mode, x);
2064 }
2065 SET_DECL_RTL (decl_elt, decl_rtl);
2066 }
2067 }
2068
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. */
2074
2075 static struct case_node *
add_case_node(struct case_node * head,tree type,tree low,tree high,tree label)2076 add_case_node (struct case_node *head, tree type, tree low, tree high,
2077 tree label)
2078 {
2079 tree min_value, max_value;
2080 struct case_node *r;
2081
2082 gcc_assert (TREE_CODE (low) == INTEGER_CST);
2083 gcc_assert (!high || TREE_CODE (high) == INTEGER_CST);
2084
2085 min_value = TYPE_MIN_VALUE (type);
2086 max_value = TYPE_MAX_VALUE (type);
2087
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))
2093 {
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;
2102 }
2103 else
2104 {
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;
2111
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);
2118
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);
2125 }
2126
2127
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;
2138 }
2139
2140 /* Maximum number of case bit tests. */
2141 #define MAX_CASE_BIT_TESTS 3
2142
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
2148
2149
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. */
2156
2157 struct case_bit_test
2158 {
2159 HOST_WIDE_INT hi;
2160 HOST_WIDE_INT lo;
2161 rtx label;
2162 int bits;
2163 };
2164
2165 /* Determine whether "1 << x" is relatively cheap in word_mode. */
2166
2167 static
lshift_cheap_p(void)2168 bool lshift_cheap_p (void)
2169 {
2170 static bool init = false;
2171 static bool cheap = true;
2172
2173 if (!init)
2174 {
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;
2179 }
2180
2181 return cheap;
2182 }
2183
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. */
2187
2188 static int
case_bit_test_cmp(const void * p1,const void * p2)2189 case_bit_test_cmp (const void *p1, const void *p2)
2190 {
2191 const struct case_bit_test *d1 = p1;
2192 const struct case_bit_test *d2 = p2;
2193
2194 return d2->bits - d1->bits;
2195 }
2196
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.
2201
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.
2208
2209 There *MUST* be MAX_CASE_BIT_TESTS or less unique case
2210 node targets. */
2211
2212 static void
emit_case_bit_tests(tree index_type,tree index_expr,tree minval,tree range,case_node_ptr nodes,rtx default_label)2213 emit_case_bit_tests (tree index_type, tree index_expr, tree minval,
2214 tree range, case_node_ptr nodes, rtx default_label)
2215 {
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;
2222
2223 count = 0;
2224 for (n = nodes; n; n = n->right)
2225 {
2226 label = label_rtx (n->code_label);
2227 for (i = 0; i < count; i++)
2228 if (label == test[i].label)
2229 break;
2230
2231 if (i == count)
2232 {
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++;
2239 }
2240 else
2241 test[i].bits++;
2242
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;
2252 }
2253
2254 qsort (test, count, sizeof(*test), case_bit_test_cmp);
2255
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 ();
2261
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);
2266
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);
2270
2271 for (i = 0; i < count; i++)
2272 {
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);
2278 }
2279
2280 emit_jump (default_label);
2281 }
2282
2283 #ifndef HAVE_casesi
2284 #define HAVE_casesi 0
2285 #endif
2286
2287 #ifndef HAVE_tablejump
2288 #define HAVE_tablejump 0
2289 #endif
2290
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. */
2296
2297 void
expand_case(tree exp)2298 expand_case (tree exp)
2299 {
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;
2310
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);
2316
2317 /* The insn after which the case dispatch should finally
2318 be emitted. Zero for a dummy. */
2319 rtx start;
2320
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;
2324
2325 /* Label to jump to if no case matches. */
2326 tree default_label_decl;
2327
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));
2332
2333 do_pending_stack_adjust ();
2334
2335 /* An ERROR_MARK occurs for various reasons including invalid data type. */
2336 if (index_type != error_mark_node)
2337 {
2338 tree elt;
2339 bitmap label_bitmap;
2340
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);
2344
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);
2350
2351 for (i = TREE_VEC_LENGTH (vec) - 1; --i >= 0; )
2352 {
2353 tree low, high;
2354 elt = TREE_VEC_ELT (vec, i);
2355
2356 low = CASE_LOW (elt);
2357 gcc_assert (low);
2358 high = CASE_HIGH (elt);
2359
2360 /* Discard empty ranges. */
2361 if (high && INT_CST_LT (high, low))
2362 continue;
2363
2364 case_list = add_case_node (case_list, index_type, low, high,
2365 CASE_LABEL (elt));
2366 }
2367
2368
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))
2373 {
2374 emit_note (NOTE_INSN_DELETED);
2375 start = get_last_insn ();
2376 }
2377
2378 default_label = label_rtx (default_label_decl);
2379
2380 before_case = get_last_insn ();
2381
2382 /* Get upper and lower bounds of case values. */
2383
2384 uniq = 0;
2385 count = 0;
2386 label_bitmap = BITMAP_ALLOC (NULL);
2387 for (n = case_list; n; n = n->right)
2388 {
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)
2392 {
2393 minval = n->low;
2394 maxval = n->high;
2395 }
2396 else
2397 {
2398 if (INT_CST_LT (n->low, minval))
2399 minval = n->low;
2400 if (INT_CST_LT (maxval, n->high))
2401 maxval = n->high;
2402 }
2403 /* A range counts double, since it requires two compares. */
2404 if (! tree_int_cst_equal (n->low, n->high))
2405 count++;
2406
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)))
2411 {
2412 bitmap_set_bit (label_bitmap, CODE_LABEL_NUMBER (lab));
2413 uniq++;
2414 }
2415 }
2416
2417 BITMAP_FREE (label_bitmap);
2418
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)
2424 {
2425 emit_jump (default_label);
2426 return;
2427 }
2428
2429 /* Compute span of values. */
2430 range = fold_build2 (MINUS_EXPR, index_type, maxval, minval);
2431
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)))
2443 {
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)
2449 {
2450 minval = build_int_cst (index_type, 0);
2451 range = maxval;
2452 }
2453 emit_case_bit_tests (index_type, index_expr, minval, range,
2454 case_list, default_label);
2455 }
2456
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. */
2461
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))
2476 {
2477 index = expand_expr (index_expr, NULL_RTX, VOIDmode, 0);
2478
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. */
2483
2484 if (GET_MODE_CLASS (GET_MODE (index)) == MODE_INT
2485 && ! have_insn_for (COMPARE, GET_MODE (index)))
2486 {
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))
2491 {
2492 index = convert_to_mode (wider_mode, index, unsignedp);
2493 break;
2494 }
2495 }
2496
2497 do_pending_stack_adjust ();
2498
2499 if (MEM_P (index))
2500 index = copy_to_reg (index);
2501
2502 /* We generate a binary decision tree to select the
2503 appropriate target code. This is done as follows:
2504
2505 The list of cases is rearranged into a binary tree,
2506 nearly optimal assuming equal probability for each case.
2507
2508 The tree is transformed into RTL, eliminating
2509 redundant test conditions at the same time.
2510
2511 If program flow could reach the end of the
2512 decision tree an unconditional jump to the
2513 default code is emitted. */
2514
2515 use_cost_table
2516 = (TREE_CODE (orig_type) != ENUMERAL_TYPE
2517 && estimate_case_costs (case_list));
2518 /* (TIGCC 20030907) Don't balance the tree when optimizing for size. A linear
2519 decision tree gives far smaller code. -- Kevin Kofler */
2520 if (!optimize_size)
2521 balance_case_nodes (&case_list, NULL);
2522 emit_case_nodes (index, case_list, default_label, index_type);
2523 emit_jump (default_label);
2524 }
2525 else
2526 {
2527 table_label = gen_label_rtx ();
2528 if (! try_casesi (index_type, index_expr, minval, range,
2529 table_label, default_label))
2530 {
2531 bool ok;
2532
2533 /* Index jumptables from zero for suitable values of
2534 minval to avoid a subtraction. */
2535 if (! optimize_size
2536 && compare_tree_int (minval, 0) > 0
2537 && compare_tree_int (minval, 3) < 0)
2538 {
2539 minval = build_int_cst (index_type, 0);
2540 range = maxval;
2541 }
2542
2543 ok = try_tablejump (index_type, index_expr, minval, range,
2544 table_label, default_label);
2545 gcc_assert (ok);
2546 }
2547
2548 /* Get table of labels to jump to, in order of case index. */
2549
2550 ncases = tree_low_cst (range, 0) + 1;
2551 labelvec = alloca (ncases * sizeof (rtx));
2552 memset (labelvec, 0, ncases * sizeof (rtx));
2553
2554 for (n = case_list; n; n = n->right)
2555 {
2556 /* Compute the low and high bounds relative to the minimum
2557 value since that should fit in a HOST_WIDE_INT while the
2558 actual values may not. */
2559 HOST_WIDE_INT i_low
2560 = tree_low_cst (fold_build2 (MINUS_EXPR, index_type,
2561 n->low, minval), 1);
2562 HOST_WIDE_INT i_high
2563 = tree_low_cst (fold_build2 (MINUS_EXPR, index_type,
2564 n->high, minval), 1);
2565 HOST_WIDE_INT i;
2566
2567 for (i = i_low; i <= i_high; i ++)
2568 labelvec[i]
2569 = gen_rtx_LABEL_REF (Pmode, label_rtx (n->code_label));
2570 }
2571
2572 /* Fill in the gaps with the default. */
2573 for (i = 0; i < ncases; i++)
2574 if (labelvec[i] == 0)
2575 labelvec[i] = gen_rtx_LABEL_REF (Pmode, default_label);
2576
2577 /* Output the table. */
2578 emit_label (table_label);
2579
2580 if (CASE_VECTOR_PC_RELATIVE || flag_pic)
2581 emit_jump_insn (gen_rtx_ADDR_DIFF_VEC (CASE_VECTOR_MODE,
2582 gen_rtx_LABEL_REF (Pmode, table_label),
2583 gen_rtvec_v (ncases, labelvec),
2584 const0_rtx, const0_rtx));
2585 else
2586 emit_jump_insn (gen_rtx_ADDR_VEC (CASE_VECTOR_MODE,
2587 gen_rtvec_v (ncases, labelvec)));
2588
2589 /* Record no drop-through after the table. */
2590 emit_barrier ();
2591 }
2592
2593 before_case = NEXT_INSN (before_case);
2594 end = get_last_insn ();
2595 fail = squeeze_notes (&before_case, &end);
2596 gcc_assert (!fail);
2597 reorder_insns (before_case, end, start);
2598 }
2599
2600 free_temp_slots ();
2601 }
2602
2603 /* Generate code to jump to LABEL if OP1 and OP2 are equal. */
2604
2605 static void
do_jump_if_equal(rtx op1,rtx op2,rtx label,int unsignedp)2606 do_jump_if_equal (rtx op1, rtx op2, rtx label, int unsignedp)
2607 {
2608 if (GET_CODE (op1) == CONST_INT && GET_CODE (op2) == CONST_INT)
2609 {
2610 if (op1 == op2)
2611 emit_jump (label);
2612 }
2613 else
2614 emit_cmp_and_jump_insns (op1, op2, EQ, NULL_RTX,
2615 (GET_MODE (op1) == VOIDmode
2616 ? GET_MODE (op2) : GET_MODE (op1)),
2617 unsignedp, label);
2618 }
2619
2620 /* Not all case values are encountered equally. This function
2621 uses a heuristic to weight case labels, in cases where that
2622 looks like a reasonable thing to do.
2623
2624 Right now, all we try to guess is text, and we establish the
2625 following weights:
2626
2627 chars above space: 16
2628 digits: 16
2629 default: 12
2630 space, punct: 8
2631 tab: 4
2632 newline: 2
2633 other "\" chars: 1
2634 remaining chars: 0
2635
2636 If we find any cases in the switch that are not either -1 or in the range
2637 of valid ASCII characters, or are control characters other than those
2638 commonly used with "\", don't treat this switch scanning text.
2639
2640 Return 1 if these nodes are suitable for cost estimation, otherwise
2641 return 0. */
2642
2643 static int
estimate_case_costs(case_node_ptr node)2644 estimate_case_costs (case_node_ptr node)
2645 {
2646 tree min_ascii = integer_minus_one_node;
2647 tree max_ascii = build_int_cst (TREE_TYPE (node->high), 127);
2648 case_node_ptr n;
2649 int i;
2650
2651 /* If we haven't already made the cost table, make it now. Note that the
2652 lower bound of the table is -1, not zero. */
2653
2654 if (! cost_table_initialized)
2655 {
2656 cost_table_initialized = 1;
2657
2658 for (i = 0; i < 128; i++)
2659 {
2660 if (ISALNUM (i))
2661 COST_TABLE (i) = 16;
2662 else if (ISPUNCT (i))
2663 COST_TABLE (i) = 8;
2664 else if (ISCNTRL (i))
2665 COST_TABLE (i) = -1;
2666 }
2667
2668 COST_TABLE (' ') = 8;
2669 COST_TABLE ('\t') = 4;
2670 COST_TABLE ('\0') = 4;
2671 COST_TABLE ('\n') = 2;
2672 COST_TABLE ('\f') = 1;
2673 COST_TABLE ('\v') = 1;
2674 COST_TABLE ('\b') = 1;
2675 }
2676
2677 /* See if all the case expressions look like text. It is text if the
2678 constant is >= -1 and the highest constant is <= 127. Do all comparisons
2679 as signed arithmetic since we don't want to ever access cost_table with a
2680 value less than -1. Also check that none of the constants in a range
2681 are strange control characters. */
2682
2683 for (n = node; n; n = n->right)
2684 {
2685 if ((INT_CST_LT (n->low, min_ascii)) || INT_CST_LT (max_ascii, n->high))
2686 return 0;
2687
2688 for (i = (HOST_WIDE_INT) TREE_INT_CST_LOW (n->low);
2689 i <= (HOST_WIDE_INT) TREE_INT_CST_LOW (n->high); i++)
2690 if (COST_TABLE (i) < 0)
2691 return 0;
2692 }
2693
2694 /* All interesting values are within the range of interesting
2695 ASCII characters. */
2696 return 1;
2697 }
2698
2699 /* Take an ordered list of case nodes
2700 and transform them into a near optimal binary tree,
2701 on the assumption that any target code selection value is as
2702 likely as any other.
2703
2704 The transformation is performed by splitting the ordered
2705 list into two equal sections plus a pivot. The parts are
2706 then attached to the pivot as left and right branches. Each
2707 branch is then transformed recursively. */
2708
2709 static void
balance_case_nodes(case_node_ptr * head,case_node_ptr parent)2710 balance_case_nodes (case_node_ptr *head, case_node_ptr parent)
2711 {
2712 case_node_ptr np;
2713
2714 np = *head;
2715 if (np)
2716 {
2717 int cost = 0;
2718 int i = 0;
2719 int ranges = 0;
2720 case_node_ptr *npp;
2721 case_node_ptr left;
2722
2723 /* Count the number of entries on branch. Also count the ranges. */
2724
2725 while (np)
2726 {
2727 if (!tree_int_cst_equal (np->low, np->high))
2728 {
2729 ranges++;
2730 if (use_cost_table)
2731 cost += COST_TABLE (TREE_INT_CST_LOW (np->high));
2732 }
2733
2734 if (use_cost_table)
2735 cost += COST_TABLE (TREE_INT_CST_LOW (np->low));
2736
2737 i++;
2738 np = np->right;
2739 }
2740
2741 if (i > 2)
2742 {
2743 /* Split this list if it is long enough for that to help. */
2744 npp = head;
2745 left = *npp;
2746 if (use_cost_table)
2747 {
2748 /* Find the place in the list that bisects the list's total cost,
2749 Here I gets half the total cost. */
2750 int n_moved = 0;
2751 i = (cost + 1) / 2;
2752 while (1)
2753 {
2754 /* Skip nodes while their cost does not reach that amount. */
2755 if (!tree_int_cst_equal ((*npp)->low, (*npp)->high))
2756 i -= COST_TABLE (TREE_INT_CST_LOW ((*npp)->high));
2757 i -= COST_TABLE (TREE_INT_CST_LOW ((*npp)->low));
2758 if (i <= 0)
2759 break;
2760 npp = &(*npp)->right;
2761 n_moved += 1;
2762 }
2763 if (n_moved == 0)
2764 {
2765 /* Leave this branch lopsided, but optimize left-hand
2766 side and fill in `parent' fields for right-hand side. */
2767 np = *head;
2768 np->parent = parent;
2769 balance_case_nodes (&np->left, np);
2770 for (; np->right; np = np->right)
2771 np->right->parent = np;
2772 return;
2773 }
2774 }
2775 /* If there are just three nodes, split at the middle one. */
2776 else if (i == 3)
2777 npp = &(*npp)->right;
2778 else
2779 {
2780 /* Find the place in the list that bisects the list's total cost,
2781 where ranges count as 2.
2782 Here I gets half the total cost. */
2783 i = (i + ranges + 1) / 2;
2784 while (1)
2785 {
2786 /* Skip nodes while their cost does not reach that amount. */
2787 if (!tree_int_cst_equal ((*npp)->low, (*npp)->high))
2788 i--;
2789 i--;
2790 if (i <= 0)
2791 break;
2792 npp = &(*npp)->right;
2793 }
2794 }
2795 *head = np = *npp;
2796 *npp = 0;
2797 np->parent = parent;
2798 np->left = left;
2799
2800 /* Optimize each of the two split parts. */
2801 balance_case_nodes (&np->left, np);
2802 balance_case_nodes (&np->right, np);
2803 }
2804 else
2805 {
2806 /* Else leave this branch as one level,
2807 but fill in `parent' fields. */
2808 np = *head;
2809 np->parent = parent;
2810 for (; np->right; np = np->right)
2811 np->right->parent = np;
2812 }
2813 }
2814 }
2815
2816 /* Search the parent sections of the case node tree
2817 to see if a test for the lower bound of NODE would be redundant.
2818 INDEX_TYPE is the type of the index expression.
2819
2820 The instructions to generate the case decision tree are
2821 output in the same order as nodes are processed so it is
2822 known that if a parent node checks the range of the current
2823 node minus one that the current node is bounded at its lower
2824 span. Thus the test would be redundant. */
2825
2826 static int
node_has_low_bound(case_node_ptr node,tree index_type)2827 node_has_low_bound (case_node_ptr node, tree index_type)
2828 {
2829 tree low_minus_one;
2830 case_node_ptr pnode;
2831
2832 /* If the lower bound of this node is the lowest value in the index type,
2833 we need not test it. */
2834
2835 if (tree_int_cst_equal (node->low, TYPE_MIN_VALUE (index_type)))
2836 return 1;
2837
2838 /* If this node has a left branch, the value at the left must be less
2839 than that at this node, so it cannot be bounded at the bottom and
2840 we need not bother testing any further. */
2841
2842 if (node->left)
2843 return 0;
2844
2845 low_minus_one = fold_build2 (MINUS_EXPR, TREE_TYPE (node->low),
2846 node->low,
2847 build_int_cst (TREE_TYPE (node->low), 1));
2848
2849 /* If the subtraction above overflowed, we can't verify anything.
2850 Otherwise, look for a parent that tests our value - 1. */
2851
2852 if (! tree_int_cst_lt (low_minus_one, node->low))
2853 return 0;
2854
2855 for (pnode = node->parent; pnode; pnode = pnode->parent)
2856 if (tree_int_cst_equal (low_minus_one, pnode->high))
2857 return 1;
2858
2859 return 0;
2860 }
2861
2862 /* Search the parent sections of the case node tree
2863 to see if a test for the upper bound of NODE would be redundant.
2864 INDEX_TYPE is the type of the index expression.
2865
2866 The instructions to generate the case decision tree are
2867 output in the same order as nodes are processed so it is
2868 known that if a parent node checks the range of the current
2869 node plus one that the current node is bounded at its upper
2870 span. Thus the test would be redundant. */
2871
2872 static int
node_has_high_bound(case_node_ptr node,tree index_type)2873 node_has_high_bound (case_node_ptr node, tree index_type)
2874 {
2875 tree high_plus_one;
2876 case_node_ptr pnode;
2877
2878 /* If there is no upper bound, obviously no test is needed. */
2879
2880 if (TYPE_MAX_VALUE (index_type) == NULL)
2881 return 1;
2882
2883 /* If the upper bound of this node is the highest value in the type
2884 of the index expression, we need not test against it. */
2885
2886 if (tree_int_cst_equal (node->high, TYPE_MAX_VALUE (index_type)))
2887 return 1;
2888
2889 /* If this node has a right branch, the value at the right must be greater
2890 than that at this node, so it cannot be bounded at the top and
2891 we need not bother testing any further. */
2892
2893 if (node->right)
2894 return 0;
2895
2896 high_plus_one = fold_build2 (PLUS_EXPR, TREE_TYPE (node->high),
2897 node->high,
2898 build_int_cst (TREE_TYPE (node->high), 1));
2899
2900 /* If the addition above overflowed, we can't verify anything.
2901 Otherwise, look for a parent that tests our value + 1. */
2902
2903 if (! tree_int_cst_lt (node->high, high_plus_one))
2904 return 0;
2905
2906 for (pnode = node->parent; pnode; pnode = pnode->parent)
2907 if (tree_int_cst_equal (high_plus_one, pnode->low))
2908 return 1;
2909
2910 return 0;
2911 }
2912
2913 /* Search the parent sections of the
2914 case node tree to see if both tests for the upper and lower
2915 bounds of NODE would be redundant. */
2916
2917 static int
node_is_bounded(case_node_ptr node,tree index_type)2918 node_is_bounded (case_node_ptr node, tree index_type)
2919 {
2920 return (node_has_low_bound (node, index_type)
2921 && node_has_high_bound (node, index_type));
2922 }
2923
2924 /* Emit step-by-step code to select a case for the value of INDEX.
2925 The thus generated decision tree follows the form of the
2926 case-node binary tree NODE, whose nodes represent test conditions.
2927 INDEX_TYPE is the type of the index of the switch.
2928
2929 Care is taken to prune redundant tests from the decision tree
2930 by detecting any boundary conditions already checked by
2931 emitted rtx. (See node_has_high_bound, node_has_low_bound
2932 and node_is_bounded, above.)
2933
2934 Where the test conditions can be shown to be redundant we emit
2935 an unconditional jump to the target code. As a further
2936 optimization, the subordinates of a tree node are examined to
2937 check for bounded nodes. In this case conditional and/or
2938 unconditional jumps as a result of the boundary check for the
2939 current node are arranged to target the subordinates associated
2940 code for out of bound conditions on the current node.
2941
2942 We can assume that when control reaches the code generated here,
2943 the index value has already been compared with the parents
2944 of this node, and determined to be on the same side of each parent
2945 as this node is. Thus, if this node tests for the value 51,
2946 and a parent tested for 52, we don't need to consider
2947 the possibility of a value greater than 51. If another parent
2948 tests for the value 50, then this node need not test anything. */
2949
2950 static void
emit_case_nodes(rtx index,case_node_ptr node,rtx default_label,tree index_type)2951 emit_case_nodes (rtx index, case_node_ptr node, rtx default_label,
2952 tree index_type)
2953 {
2954 /* If INDEX has an unsigned type, we must make unsigned branches. */
2955 int unsignedp = TYPE_UNSIGNED (index_type);
2956 enum machine_mode mode = GET_MODE (index);
2957 enum machine_mode imode = TYPE_MODE (index_type);
2958
2959 /* Handle indices detected as constant during RTL expansion. */
2960 if (mode == VOIDmode)
2961 mode = imode;
2962
2963 /* See if our parents have already tested everything for us.
2964 If they have, emit an unconditional jump for this node. */
2965 if (node_is_bounded (node, index_type))
2966 emit_jump (label_rtx (node->code_label));
2967
2968 else if (tree_int_cst_equal (node->low, node->high))
2969 {
2970 /* Node is single valued. First see if the index expression matches
2971 this node and then check our children, if any. */
2972
2973 do_jump_if_equal (index,
2974 convert_modes (mode, imode,
2975 expand_expr (node->low, NULL_RTX,
2976 VOIDmode, 0),
2977 unsignedp),
2978 label_rtx (node->code_label), unsignedp);
2979
2980 if (node->right != 0 && node->left != 0)
2981 {
2982 /* This node has children on both sides.
2983 Dispatch to one side or the other
2984 by comparing the index value with this node's value.
2985 If one subtree is bounded, check that one first,
2986 so we can avoid real branches in the tree. */
2987
2988 if (node_is_bounded (node->right, index_type))
2989 {
2990 emit_cmp_and_jump_insns (index,
2991 convert_modes
2992 (mode, imode,
2993 expand_expr (node->high, NULL_RTX,
2994 VOIDmode, 0),
2995 unsignedp),
2996 GT, NULL_RTX, mode, unsignedp,
2997 label_rtx (node->right->code_label));
2998 emit_case_nodes (index, node->left, default_label, index_type);
2999 }
3000
3001 else if (node_is_bounded (node->left, index_type))
3002 {
3003 emit_cmp_and_jump_insns (index,
3004 convert_modes
3005 (mode, imode,
3006 expand_expr (node->high, NULL_RTX,
3007 VOIDmode, 0),
3008 unsignedp),
3009 LT, NULL_RTX, mode, unsignedp,
3010 label_rtx (node->left->code_label));
3011 emit_case_nodes (index, node->right, default_label, index_type);
3012 }
3013
3014 /* If both children are single-valued cases with no
3015 children, finish up all the work. This way, we can save
3016 one ordered comparison. */
3017 else if (tree_int_cst_equal (node->right->low, node->right->high)
3018 && node->right->left == 0
3019 && node->right->right == 0
3020 && tree_int_cst_equal (node->left->low, node->left->high)
3021 && node->left->left == 0
3022 && node->left->right == 0)
3023 {
3024 /* Neither node is bounded. First distinguish the two sides;
3025 then emit the code for one side at a time. */
3026
3027 /* See if the value matches what the right hand side
3028 wants. */
3029 do_jump_if_equal (index,
3030 convert_modes (mode, imode,
3031 expand_expr (node->right->low,
3032 NULL_RTX,
3033 VOIDmode, 0),
3034 unsignedp),
3035 label_rtx (node->right->code_label),
3036 unsignedp);
3037
3038 /* See if the value matches what the left hand side
3039 wants. */
3040 do_jump_if_equal (index,
3041 convert_modes (mode, imode,
3042 expand_expr (node->left->low,
3043 NULL_RTX,
3044 VOIDmode, 0),
3045 unsignedp),
3046 label_rtx (node->left->code_label),
3047 unsignedp);
3048 }
3049
3050 else
3051 {
3052 /* Neither node is bounded. First distinguish the two sides;
3053 then emit the code for one side at a time. */
3054
3055 tree test_label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
3056
3057 /* See if the value is on the right. */
3058 emit_cmp_and_jump_insns (index,
3059 convert_modes
3060 (mode, imode,
3061 expand_expr (node->high, NULL_RTX,
3062 VOIDmode, 0),
3063 unsignedp),
3064 GT, NULL_RTX, mode, unsignedp,
3065 label_rtx (test_label));
3066
3067 /* Value must be on the left.
3068 Handle the left-hand subtree. */
3069 emit_case_nodes (index, node->left, default_label, index_type);
3070 /* If left-hand subtree does nothing,
3071 go to default. */
3072 emit_jump (default_label);
3073
3074 /* Code branches here for the right-hand subtree. */
3075 expand_label (test_label);
3076 emit_case_nodes (index, node->right, default_label, index_type);
3077 }
3078 }
3079
3080 else if (node->right != 0 && node->left == 0)
3081 {
3082 /* Here we have a right child but no left so we issue a conditional
3083 branch to default and process the right child.
3084
3085 Omit the conditional branch to default if the right child
3086 does not have any children and is single valued; it would
3087 cost too much space to save so little time. */
3088
3089 /* (TIGCC 20030907) Also omit the conditional branch to default if we are
3090 optimizing for size. -- Kevin Kofler
3091 (TIGCC 20040719) But don't omit branches which are needed for
3092 correctness in case ranges. -- Kevin Kofler */
3093
3094 if (node->right->right || node->right->left
3095 || !tree_int_cst_equal (node->right->low, node->right->high))
3096 {
3097 if (!node_has_low_bound (node, index_type)
3098 && (!optimize_size
3099 || !tree_int_cst_equal (node->right->low, node->right->high)))
3100 {
3101 emit_cmp_and_jump_insns (index,
3102 convert_modes
3103 (mode, imode,
3104 expand_expr (node->high, NULL_RTX,
3105 VOIDmode, 0),
3106 unsignedp),
3107 LT, NULL_RTX, mode, unsignedp,
3108 default_label);
3109 }
3110
3111 emit_case_nodes (index, node->right, default_label, index_type);
3112 }
3113 else
3114 /* We cannot process node->right normally
3115 since we haven't ruled out the numbers less than
3116 this node's value. So handle node->right explicitly. */
3117 do_jump_if_equal (index,
3118 convert_modes
3119 (mode, imode,
3120 expand_expr (node->right->low, NULL_RTX,
3121 VOIDmode, 0),
3122 unsignedp),
3123 label_rtx (node->right->code_label), unsignedp);
3124 }
3125
3126 else if (node->right == 0 && node->left != 0)
3127 {
3128 /* Just one subtree, on the left. */
3129 if (node->left->left || node->left->right
3130 || !tree_int_cst_equal (node->left->low, node->left->high))
3131 {
3132 if (!node_has_high_bound (node, index_type))
3133 {
3134 emit_cmp_and_jump_insns (index,
3135 convert_modes
3136 (mode, imode,
3137 expand_expr (node->high, NULL_RTX,
3138 VOIDmode, 0),
3139 unsignedp),
3140 GT, NULL_RTX, mode, unsignedp,
3141 default_label);
3142 }
3143
3144 emit_case_nodes (index, node->left, default_label, index_type);
3145 }
3146 else
3147 /* We cannot process node->left normally
3148 since we haven't ruled out the numbers less than
3149 this node's value. So handle node->left explicitly. */
3150 do_jump_if_equal (index,
3151 convert_modes
3152 (mode, imode,
3153 expand_expr (node->left->low, NULL_RTX,
3154 VOIDmode, 0),
3155 unsignedp),
3156 label_rtx (node->left->code_label), unsignedp);
3157 }
3158 }
3159 else
3160 {
3161 /* Node is a range. These cases are very similar to those for a single
3162 value, except that we do not start by testing whether this node
3163 is the one to branch to. */
3164
3165 if (node->right != 0 && node->left != 0)
3166 {
3167 /* Node has subtrees on both sides.
3168 If the right-hand subtree is bounded,
3169 test for it first, since we can go straight there.
3170 Otherwise, we need to make a branch in the control structure,
3171 then handle the two subtrees. */
3172 tree test_label = 0;
3173
3174 if (node_is_bounded (node->right, index_type))
3175 /* Right hand node is fully bounded so we can eliminate any
3176 testing and branch directly to the target code. */
3177 emit_cmp_and_jump_insns (index,
3178 convert_modes
3179 (mode, imode,
3180 expand_expr (node->high, NULL_RTX,
3181 VOIDmode, 0),
3182 unsignedp),
3183 GT, NULL_RTX, mode, unsignedp,
3184 label_rtx (node->right->code_label));
3185 else
3186 {
3187 /* Right hand node requires testing.
3188 Branch to a label where we will handle it later. */
3189
3190 test_label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
3191 emit_cmp_and_jump_insns (index,
3192 convert_modes
3193 (mode, imode,
3194 expand_expr (node->high, NULL_RTX,
3195 VOIDmode, 0),
3196 unsignedp),
3197 GT, NULL_RTX, mode, unsignedp,
3198 label_rtx (test_label));
3199 }
3200
3201 /* Value belongs to this node or to the left-hand subtree. */
3202
3203 emit_cmp_and_jump_insns (index,
3204 convert_modes
3205 (mode, imode,
3206 expand_expr (node->low, NULL_RTX,
3207 VOIDmode, 0),
3208 unsignedp),
3209 GE, NULL_RTX, mode, unsignedp,
3210 label_rtx (node->code_label));
3211
3212 /* Handle the left-hand subtree. */
3213 emit_case_nodes (index, node->left, default_label, index_type);
3214
3215 /* If right node had to be handled later, do that now. */
3216
3217 if (test_label)
3218 {
3219 /* If the left-hand subtree fell through,
3220 don't let it fall into the right-hand subtree. */
3221 emit_jump (default_label);
3222
3223 expand_label (test_label);
3224 emit_case_nodes (index, node->right, default_label, index_type);
3225 }
3226 }
3227
3228 else if (node->right != 0 && node->left == 0)
3229 {
3230 /* Deal with values to the left of this node,
3231 if they are possible. */
3232 if (!node_has_low_bound (node, index_type))
3233 {
3234 emit_cmp_and_jump_insns (index,
3235 convert_modes
3236 (mode, imode,
3237 expand_expr (node->low, NULL_RTX,
3238 VOIDmode, 0),
3239 unsignedp),
3240 LT, NULL_RTX, mode, unsignedp,
3241 default_label);
3242 }
3243
3244 /* Value belongs to this node or to the right-hand subtree. */
3245
3246 emit_cmp_and_jump_insns (index,
3247 convert_modes
3248 (mode, imode,
3249 expand_expr (node->high, NULL_RTX,
3250 VOIDmode, 0),
3251 unsignedp),
3252 LE, NULL_RTX, mode, unsignedp,
3253 label_rtx (node->code_label));
3254
3255 emit_case_nodes (index, node->right, default_label, index_type);
3256 }
3257
3258 else if (node->right == 0 && node->left != 0)
3259 {
3260 /* Deal with values to the right of this node,
3261 if they are possible. */
3262 if (!node_has_high_bound (node, index_type))
3263 {
3264 emit_cmp_and_jump_insns (index,
3265 convert_modes
3266 (mode, imode,
3267 expand_expr (node->high, NULL_RTX,
3268 VOIDmode, 0),
3269 unsignedp),
3270 GT, NULL_RTX, mode, unsignedp,
3271 default_label);
3272 }
3273
3274 /* Value belongs to this node or to the left-hand subtree. */
3275
3276 emit_cmp_and_jump_insns (index,
3277 convert_modes
3278 (mode, imode,
3279 expand_expr (node->low, NULL_RTX,
3280 VOIDmode, 0),
3281 unsignedp),
3282 GE, NULL_RTX, mode, unsignedp,
3283 label_rtx (node->code_label));
3284
3285 emit_case_nodes (index, node->left, default_label, index_type);
3286 }
3287
3288 else
3289 {
3290 /* Node has no children so we check low and high bounds to remove
3291 redundant tests. Only one of the bounds can exist,
3292 since otherwise this node is bounded--a case tested already. */
3293 int high_bound = node_has_high_bound (node, index_type);
3294 int low_bound = node_has_low_bound (node, index_type);
3295
3296 if (!high_bound && low_bound)
3297 {
3298 emit_cmp_and_jump_insns (index,
3299 convert_modes
3300 (mode, imode,
3301 expand_expr (node->high, NULL_RTX,
3302 VOIDmode, 0),
3303 unsignedp),
3304 GT, NULL_RTX, mode, unsignedp,
3305 default_label);
3306 }
3307
3308 else if (!low_bound && high_bound)
3309 {
3310 emit_cmp_and_jump_insns (index,
3311 convert_modes
3312 (mode, imode,
3313 expand_expr (node->low, NULL_RTX,
3314 VOIDmode, 0),
3315 unsignedp),
3316 LT, NULL_RTX, mode, unsignedp,
3317 default_label);
3318 }
3319 else if (!low_bound && !high_bound)
3320 {
3321 /* Widen LOW and HIGH to the same width as INDEX. */
3322 tree type = lang_hooks.types.type_for_mode (mode, unsignedp);
3323 tree low = build1 (CONVERT_EXPR, type, node->low);
3324 tree high = build1 (CONVERT_EXPR, type, node->high);
3325 rtx low_rtx, new_index, new_bound;
3326
3327 /* Instead of doing two branches, emit one unsigned branch for
3328 (index-low) > (high-low). */
3329 low_rtx = expand_expr (low, NULL_RTX, mode, 0);
3330 new_index = expand_simple_binop (mode, MINUS, index, low_rtx,
3331 NULL_RTX, unsignedp,
3332 OPTAB_WIDEN);
3333 new_bound = expand_expr (fold_build2 (MINUS_EXPR, type,
3334 high, low),
3335 NULL_RTX, mode, 0);
3336
3337 emit_cmp_and_jump_insns (new_index, new_bound, GT, NULL_RTX,
3338 mode, 1, default_label);
3339 }
3340
3341 emit_jump (label_rtx (node->code_label));
3342 }
3343 }
3344 }
3345