Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-ssa-ccp.c @ 47:3bfb6c00c1e0
update it from 4.4.2 to 4.4.3.
author | kent <kent@cr.ie.u-ryukyu.ac.jp> |
---|---|
date | Sun, 07 Feb 2010 17:44:34 +0900 |
parents | 58ad6c70ea60 |
children | 77e2b8dfacca |
rev | line source |
---|---|
0 | 1 /* Conditional constant propagation pass for the GNU compiler. |
2 Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 | |
3 Free Software Foundation, Inc. | |
4 Adapted from original RTL SSA-CCP by Daniel Berlin <dberlin@dberlin.org> | |
5 Adapted to GIMPLE trees by Diego Novillo <dnovillo@redhat.com> | |
6 | |
7 This file is part of GCC. | |
8 | |
9 GCC is free software; you can redistribute it and/or modify it | |
10 under the terms of the GNU General Public License as published by the | |
11 Free Software Foundation; either version 3, or (at your option) any | |
12 later version. | |
13 | |
14 GCC is distributed in the hope that it will be useful, but WITHOUT | |
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
16 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
17 for more details. | |
18 | |
19 You should have received a copy of the GNU General Public License | |
20 along with GCC; see the file COPYING3. If not see | |
21 <http://www.gnu.org/licenses/>. */ | |
22 | |
23 /* Conditional constant propagation (CCP) is based on the SSA | |
24 propagation engine (tree-ssa-propagate.c). Constant assignments of | |
25 the form VAR = CST are propagated from the assignments into uses of | |
26 VAR, which in turn may generate new constants. The simulation uses | |
27 a four level lattice to keep track of constant values associated | |
28 with SSA names. Given an SSA name V_i, it may take one of the | |
29 following values: | |
30 | |
31 UNINITIALIZED -> the initial state of the value. This value | |
32 is replaced with a correct initial value | |
33 the first time the value is used, so the | |
34 rest of the pass does not need to care about | |
35 it. Using this value simplifies initialization | |
36 of the pass, and prevents us from needlessly | |
37 scanning statements that are never reached. | |
38 | |
39 UNDEFINED -> V_i is a local variable whose definition | |
40 has not been processed yet. Therefore we | |
41 don't yet know if its value is a constant | |
42 or not. | |
43 | |
44 CONSTANT -> V_i has been found to hold a constant | |
45 value C. | |
46 | |
47 VARYING -> V_i cannot take a constant value, or if it | |
48 does, it is not possible to determine it | |
49 at compile time. | |
50 | |
51 The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node: | |
52 | |
53 1- In ccp_visit_stmt, we are interested in assignments whose RHS | |
54 evaluates into a constant and conditional jumps whose predicate | |
55 evaluates into a boolean true or false. When an assignment of | |
56 the form V_i = CONST is found, V_i's lattice value is set to | |
57 CONSTANT and CONST is associated with it. This causes the | |
58 propagation engine to add all the SSA edges coming out the | |
59 assignment into the worklists, so that statements that use V_i | |
60 can be visited. | |
61 | |
62 If the statement is a conditional with a constant predicate, we | |
63 mark the outgoing edges as executable or not executable | |
64 depending on the predicate's value. This is then used when | |
65 visiting PHI nodes to know when a PHI argument can be ignored. | |
66 | |
67 | |
68 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the | |
69 same constant C, then the LHS of the PHI is set to C. This | |
70 evaluation is known as the "meet operation". Since one of the | |
71 goals of this evaluation is to optimistically return constant | |
72 values as often as possible, it uses two main short cuts: | |
73 | |
74 - If an argument is flowing in through a non-executable edge, it | |
75 is ignored. This is useful in cases like this: | |
76 | |
77 if (PRED) | |
78 a_9 = 3; | |
79 else | |
80 a_10 = 100; | |
81 a_11 = PHI (a_9, a_10) | |
82 | |
83 If PRED is known to always evaluate to false, then we can | |
84 assume that a_11 will always take its value from a_10, meaning | |
85 that instead of consider it VARYING (a_9 and a_10 have | |
86 different values), we can consider it CONSTANT 100. | |
87 | |
88 - If an argument has an UNDEFINED value, then it does not affect | |
89 the outcome of the meet operation. If a variable V_i has an | |
90 UNDEFINED value, it means that either its defining statement | |
91 hasn't been visited yet or V_i has no defining statement, in | |
92 which case the original symbol 'V' is being used | |
93 uninitialized. Since 'V' is a local variable, the compiler | |
94 may assume any initial value for it. | |
95 | |
96 | |
97 After propagation, every variable V_i that ends up with a lattice | |
98 value of CONSTANT will have the associated constant value in the | |
99 array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for | |
100 final substitution and folding. | |
101 | |
102 | |
103 Constant propagation in stores and loads (STORE-CCP) | |
104 ---------------------------------------------------- | |
105 | |
106 While CCP has all the logic to propagate constants in GIMPLE | |
107 registers, it is missing the ability to associate constants with | |
108 stores and loads (i.e., pointer dereferences, structures and | |
109 global/aliased variables). We don't keep loads and stores in | |
110 SSA, but we do build a factored use-def web for them (in the | |
111 virtual operands). | |
112 | |
113 For instance, consider the following code fragment: | |
114 | |
115 struct A a; | |
116 const int B = 42; | |
117 | |
118 void foo (int i) | |
119 { | |
120 if (i > 10) | |
121 a.a = 42; | |
122 else | |
123 { | |
124 a.b = 21; | |
125 a.a = a.b + 21; | |
126 } | |
127 | |
128 if (a.a != B) | |
129 never_executed (); | |
130 } | |
131 | |
132 We should be able to deduce that the predicate 'a.a != B' is always | |
133 false. To achieve this, we associate constant values to the SSA | |
134 names in the VDEF operands for each store. Additionally, | |
135 since we also glob partial loads/stores with the base symbol, we | |
136 also keep track of the memory reference where the constant value | |
137 was stored (in the MEM_REF field of PROP_VALUE_T). For instance, | |
138 | |
139 # a_5 = VDEF <a_4> | |
140 a.a = 2; | |
141 | |
142 # VUSE <a_5> | |
143 x_3 = a.b; | |
144 | |
145 In the example above, CCP will associate value '2' with 'a_5', but | |
146 it would be wrong to replace the load from 'a.b' with '2', because | |
147 '2' had been stored into a.a. | |
148 | |
149 Note that the initial value of virtual operands is VARYING, not | |
150 UNDEFINED. Consider, for instance global variables: | |
151 | |
152 int A; | |
153 | |
154 foo (int i) | |
155 { | |
156 if (i_3 > 10) | |
157 A_4 = 3; | |
158 # A_5 = PHI (A_4, A_2); | |
159 | |
160 # VUSE <A_5> | |
161 A.0_6 = A; | |
162 | |
163 return A.0_6; | |
164 } | |
165 | |
166 The value of A_2 cannot be assumed to be UNDEFINED, as it may have | |
167 been defined outside of foo. If we were to assume it UNDEFINED, we | |
168 would erroneously optimize the above into 'return 3;'. | |
169 | |
170 Though STORE-CCP is not too expensive, it does have to do more work | |
171 than regular CCP, so it is only enabled at -O2. Both regular CCP | |
172 and STORE-CCP use the exact same algorithm. The only distinction | |
173 is that when doing STORE-CCP, the boolean variable DO_STORE_CCP is | |
174 set to true. This affects the evaluation of statements and PHI | |
175 nodes. | |
176 | |
177 References: | |
178 | |
179 Constant propagation with conditional branches, | |
180 Wegman and Zadeck, ACM TOPLAS 13(2):181-210. | |
181 | |
182 Building an Optimizing Compiler, | |
183 Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9. | |
184 | |
185 Advanced Compiler Design and Implementation, | |
186 Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */ | |
187 | |
188 #include "config.h" | |
189 #include "system.h" | |
190 #include "coretypes.h" | |
191 #include "tm.h" | |
192 #include "tree.h" | |
193 #include "flags.h" | |
194 #include "rtl.h" | |
195 #include "tm_p.h" | |
196 #include "ggc.h" | |
197 #include "basic-block.h" | |
198 #include "output.h" | |
199 #include "expr.h" | |
200 #include "function.h" | |
201 #include "diagnostic.h" | |
202 #include "timevar.h" | |
203 #include "tree-dump.h" | |
204 #include "tree-flow.h" | |
205 #include "tree-pass.h" | |
206 #include "tree-ssa-propagate.h" | |
207 #include "value-prof.h" | |
208 #include "langhooks.h" | |
209 #include "target.h" | |
210 #include "toplev.h" | |
211 | |
212 | |
213 /* Possible lattice values. */ | |
214 typedef enum | |
215 { | |
216 UNINITIALIZED, | |
217 UNDEFINED, | |
218 CONSTANT, | |
219 VARYING | |
220 } ccp_lattice_t; | |
221 | |
222 /* Array of propagated constant values. After propagation, | |
223 CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If | |
224 the constant is held in an SSA name representing a memory store | |
225 (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual | |
226 memory reference used to store (i.e., the LHS of the assignment | |
227 doing the store). */ | |
228 static prop_value_t *const_val; | |
229 | |
230 static void canonicalize_float_value (prop_value_t *); | |
231 | |
232 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */ | |
233 | |
234 static void | |
235 dump_lattice_value (FILE *outf, const char *prefix, prop_value_t val) | |
236 { | |
237 switch (val.lattice_val) | |
238 { | |
239 case UNINITIALIZED: | |
240 fprintf (outf, "%sUNINITIALIZED", prefix); | |
241 break; | |
242 case UNDEFINED: | |
243 fprintf (outf, "%sUNDEFINED", prefix); | |
244 break; | |
245 case VARYING: | |
246 fprintf (outf, "%sVARYING", prefix); | |
247 break; | |
248 case CONSTANT: | |
249 fprintf (outf, "%sCONSTANT ", prefix); | |
250 print_generic_expr (outf, val.value, dump_flags); | |
251 break; | |
252 default: | |
253 gcc_unreachable (); | |
254 } | |
255 } | |
256 | |
257 | |
258 /* Print lattice value VAL to stderr. */ | |
259 | |
260 void debug_lattice_value (prop_value_t val); | |
261 | |
262 void | |
263 debug_lattice_value (prop_value_t val) | |
264 { | |
265 dump_lattice_value (stderr, "", val); | |
266 fprintf (stderr, "\n"); | |
267 } | |
268 | |
269 | |
270 | |
271 /* If SYM is a constant variable with known value, return the value. | |
272 NULL_TREE is returned otherwise. */ | |
273 | |
274 tree | |
275 get_symbol_constant_value (tree sym) | |
276 { | |
277 if (TREE_STATIC (sym) | |
278 && TREE_READONLY (sym) | |
279 && !MTAG_P (sym)) | |
280 { | |
281 tree val = DECL_INITIAL (sym); | |
282 if (val) | |
283 { | |
284 STRIP_USELESS_TYPE_CONVERSION (val); | |
285 if (is_gimple_min_invariant (val)) | |
286 return val; | |
287 } | |
288 /* Variables declared 'const' without an initializer | |
289 have zero as the initializer if they may not be | |
290 overridden at link or run time. */ | |
291 if (!val | |
292 && !DECL_EXTERNAL (sym) | |
293 && targetm.binds_local_p (sym) | |
294 && (INTEGRAL_TYPE_P (TREE_TYPE (sym)) | |
295 || SCALAR_FLOAT_TYPE_P (TREE_TYPE (sym)))) | |
296 return fold_convert (TREE_TYPE (sym), integer_zero_node); | |
297 } | |
298 | |
299 return NULL_TREE; | |
300 } | |
301 | |
302 /* Compute a default value for variable VAR and store it in the | |
303 CONST_VAL array. The following rules are used to get default | |
304 values: | |
305 | |
306 1- Global and static variables that are declared constant are | |
307 considered CONSTANT. | |
308 | |
309 2- Any other value is considered UNDEFINED. This is useful when | |
310 considering PHI nodes. PHI arguments that are undefined do not | |
311 change the constant value of the PHI node, which allows for more | |
312 constants to be propagated. | |
313 | |
314 3- Variables defined by statements other than assignments and PHI | |
315 nodes are considered VARYING. | |
316 | |
317 4- Initial values of variables that are not GIMPLE registers are | |
318 considered VARYING. */ | |
319 | |
320 static prop_value_t | |
321 get_default_value (tree var) | |
322 { | |
323 tree sym = SSA_NAME_VAR (var); | |
324 prop_value_t val = { UNINITIALIZED, NULL_TREE }; | |
325 tree cst_val; | |
326 | |
327 if (!is_gimple_reg (var)) | |
328 { | |
329 /* Short circuit for regular CCP. We are not interested in any | |
330 non-register when DO_STORE_CCP is false. */ | |
331 val.lattice_val = VARYING; | |
332 } | |
333 else if ((cst_val = get_symbol_constant_value (sym)) != NULL_TREE) | |
334 { | |
335 /* Globals and static variables declared 'const' take their | |
336 initial value. */ | |
337 val.lattice_val = CONSTANT; | |
338 val.value = cst_val; | |
339 } | |
340 else | |
341 { | |
342 gimple stmt = SSA_NAME_DEF_STMT (var); | |
343 | |
344 if (gimple_nop_p (stmt)) | |
345 { | |
346 /* Variables defined by an empty statement are those used | |
347 before being initialized. If VAR is a local variable, we | |
348 can assume initially that it is UNDEFINED, otherwise we must | |
349 consider it VARYING. */ | |
350 if (is_gimple_reg (sym) && TREE_CODE (sym) != PARM_DECL) | |
351 val.lattice_val = UNDEFINED; | |
352 else | |
353 val.lattice_val = VARYING; | |
354 } | |
355 else if (is_gimple_assign (stmt) | |
356 /* Value-returning GIMPLE_CALL statements assign to | |
357 a variable, and are treated similarly to GIMPLE_ASSIGN. */ | |
358 || (is_gimple_call (stmt) | |
359 && gimple_call_lhs (stmt) != NULL_TREE) | |
360 || gimple_code (stmt) == GIMPLE_PHI) | |
361 { | |
362 /* Any other variable defined by an assignment or a PHI node | |
363 is considered UNDEFINED. */ | |
364 val.lattice_val = UNDEFINED; | |
365 } | |
366 else | |
367 { | |
368 /* Otherwise, VAR will never take on a constant value. */ | |
369 val.lattice_val = VARYING; | |
370 } | |
371 } | |
372 | |
373 return val; | |
374 } | |
375 | |
376 | |
377 /* Get the constant value associated with variable VAR. */ | |
378 | |
379 static inline prop_value_t * | |
380 get_value (tree var) | |
381 { | |
382 prop_value_t *val; | |
383 | |
384 if (const_val == NULL) | |
385 return NULL; | |
386 | |
387 val = &const_val[SSA_NAME_VERSION (var)]; | |
388 if (val->lattice_val == UNINITIALIZED) | |
389 *val = get_default_value (var); | |
390 | |
391 canonicalize_float_value (val); | |
392 | |
393 return val; | |
394 } | |
395 | |
396 /* Sets the value associated with VAR to VARYING. */ | |
397 | |
398 static inline void | |
399 set_value_varying (tree var) | |
400 { | |
401 prop_value_t *val = &const_val[SSA_NAME_VERSION (var)]; | |
402 | |
403 val->lattice_val = VARYING; | |
404 val->value = NULL_TREE; | |
405 } | |
406 | |
407 /* For float types, modify the value of VAL to make ccp work correctly | |
408 for non-standard values (-0, NaN): | |
409 | |
410 If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0. | |
411 If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED. | |
412 This is to fix the following problem (see PR 29921): Suppose we have | |
413 | |
414 x = 0.0 * y | |
415 | |
416 and we set value of y to NaN. This causes value of x to be set to NaN. | |
417 When we later determine that y is in fact VARYING, fold uses the fact | |
418 that HONOR_NANS is false, and we try to change the value of x to 0, | |
419 causing an ICE. With HONOR_NANS being false, the real appearance of | |
420 NaN would cause undefined behavior, though, so claiming that y (and x) | |
421 are UNDEFINED initially is correct. */ | |
422 | |
423 static void | |
424 canonicalize_float_value (prop_value_t *val) | |
425 { | |
426 enum machine_mode mode; | |
427 tree type; | |
428 REAL_VALUE_TYPE d; | |
429 | |
430 if (val->lattice_val != CONSTANT | |
431 || TREE_CODE (val->value) != REAL_CST) | |
432 return; | |
433 | |
434 d = TREE_REAL_CST (val->value); | |
435 type = TREE_TYPE (val->value); | |
436 mode = TYPE_MODE (type); | |
437 | |
438 if (!HONOR_SIGNED_ZEROS (mode) | |
439 && REAL_VALUE_MINUS_ZERO (d)) | |
440 { | |
441 val->value = build_real (type, dconst0); | |
442 return; | |
443 } | |
444 | |
445 if (!HONOR_NANS (mode) | |
446 && REAL_VALUE_ISNAN (d)) | |
447 { | |
448 val->lattice_val = UNDEFINED; | |
449 val->value = NULL; | |
450 return; | |
451 } | |
452 } | |
453 | |
454 /* Set the value for variable VAR to NEW_VAL. Return true if the new | |
455 value is different from VAR's previous value. */ | |
456 | |
457 static bool | |
458 set_lattice_value (tree var, prop_value_t new_val) | |
459 { | |
460 prop_value_t *old_val = get_value (var); | |
461 | |
462 canonicalize_float_value (&new_val); | |
463 | |
464 /* Lattice transitions must always be monotonically increasing in | |
465 value. If *OLD_VAL and NEW_VAL are the same, return false to | |
466 inform the caller that this was a non-transition. */ | |
467 | |
468 gcc_assert (old_val->lattice_val < new_val.lattice_val | |
469 || (old_val->lattice_val == new_val.lattice_val | |
470 && ((!old_val->value && !new_val.value) | |
471 || operand_equal_p (old_val->value, new_val.value, 0)))); | |
472 | |
473 if (old_val->lattice_val != new_val.lattice_val) | |
474 { | |
475 if (dump_file && (dump_flags & TDF_DETAILS)) | |
476 { | |
477 dump_lattice_value (dump_file, "Lattice value changed to ", new_val); | |
478 fprintf (dump_file, ". Adding SSA edges to worklist.\n"); | |
479 } | |
480 | |
481 *old_val = new_val; | |
482 | |
483 gcc_assert (new_val.lattice_val != UNDEFINED); | |
484 return true; | |
485 } | |
486 | |
487 return false; | |
488 } | |
489 | |
490 | |
491 /* Return the likely CCP lattice value for STMT. | |
492 | |
493 If STMT has no operands, then return CONSTANT. | |
494 | |
495 Else if undefinedness of operands of STMT cause its value to be | |
496 undefined, then return UNDEFINED. | |
497 | |
498 Else if any operands of STMT are constants, then return CONSTANT. | |
499 | |
500 Else return VARYING. */ | |
501 | |
502 static ccp_lattice_t | |
503 likely_value (gimple stmt) | |
504 { | |
505 bool has_constant_operand, has_undefined_operand, all_undefined_operands; | |
506 tree use; | |
507 ssa_op_iter iter; | |
508 | |
509 enum gimple_code code = gimple_code (stmt); | |
510 | |
511 /* This function appears to be called only for assignments, calls, | |
512 conditionals, and switches, due to the logic in visit_stmt. */ | |
513 gcc_assert (code == GIMPLE_ASSIGN | |
514 || code == GIMPLE_CALL | |
515 || code == GIMPLE_COND | |
516 || code == GIMPLE_SWITCH); | |
517 | |
518 /* If the statement has volatile operands, it won't fold to a | |
519 constant value. */ | |
520 if (gimple_has_volatile_ops (stmt)) | |
521 return VARYING; | |
522 | |
523 /* If we are not doing store-ccp, statements with loads | |
524 and/or stores will never fold into a constant. */ | |
525 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)) | |
526 return VARYING; | |
527 | |
528 /* Note that only a GIMPLE_SINGLE_RHS assignment can satisfy | |
529 is_gimple_min_invariant, so we do not consider calls or | |
530 other forms of assignment. */ | |
531 if (gimple_assign_single_p (stmt) | |
532 && is_gimple_min_invariant (gimple_assign_rhs1 (stmt))) | |
533 return CONSTANT; | |
534 | |
535 if (code == GIMPLE_COND | |
536 && is_gimple_min_invariant (gimple_cond_lhs (stmt)) | |
537 && is_gimple_min_invariant (gimple_cond_rhs (stmt))) | |
538 return CONSTANT; | |
539 | |
540 if (code == GIMPLE_SWITCH | |
541 && is_gimple_min_invariant (gimple_switch_index (stmt))) | |
542 return CONSTANT; | |
543 | |
544 /* Arrive here for more complex cases. */ | |
545 | |
546 has_constant_operand = false; | |
547 has_undefined_operand = false; | |
548 all_undefined_operands = true; | |
549 FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE | SSA_OP_VUSE) | |
550 { | |
551 prop_value_t *val = get_value (use); | |
552 | |
553 if (val->lattice_val == UNDEFINED) | |
554 has_undefined_operand = true; | |
555 else | |
556 all_undefined_operands = false; | |
557 | |
558 if (val->lattice_val == CONSTANT) | |
559 has_constant_operand = true; | |
560 } | |
561 | |
562 /* If the operation combines operands like COMPLEX_EXPR make sure to | |
563 not mark the result UNDEFINED if only one part of the result is | |
564 undefined. */ | |
565 if (has_undefined_operand && all_undefined_operands) | |
566 return UNDEFINED; | |
567 else if (code == GIMPLE_ASSIGN && has_undefined_operand) | |
568 { | |
569 switch (gimple_assign_rhs_code (stmt)) | |
570 { | |
571 /* Unary operators are handled with all_undefined_operands. */ | |
572 case PLUS_EXPR: | |
573 case MINUS_EXPR: | |
574 case POINTER_PLUS_EXPR: | |
575 /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected. | |
576 Not bitwise operators, one VARYING operand may specify the | |
577 result completely. Not logical operators for the same reason. | |
578 Not COMPLEX_EXPR as one VARYING operand makes the result partly | |
579 not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because | |
580 the undefined operand may be promoted. */ | |
581 return UNDEFINED; | |
582 | |
583 default: | |
584 ; | |
585 } | |
586 } | |
587 /* If there was an UNDEFINED operand but the result may be not UNDEFINED | |
588 fall back to VARYING even if there were CONSTANT operands. */ | |
589 if (has_undefined_operand) | |
590 return VARYING; | |
591 | |
592 if (has_constant_operand | |
593 /* We do not consider virtual operands here -- load from read-only | |
594 memory may have only VARYING virtual operands, but still be | |
595 constant. */ | |
596 || ZERO_SSA_OPERANDS (stmt, SSA_OP_USE)) | |
597 return CONSTANT; | |
598 | |
599 return VARYING; | |
600 } | |
601 | |
602 /* Returns true if STMT cannot be constant. */ | |
603 | |
604 static bool | |
605 surely_varying_stmt_p (gimple stmt) | |
606 { | |
607 /* If the statement has operands that we cannot handle, it cannot be | |
608 constant. */ | |
609 if (gimple_has_volatile_ops (stmt)) | |
610 return true; | |
611 | |
612 if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)) | |
613 return true; | |
614 | |
615 /* If it is a call and does not return a value or is not a | |
616 builtin and not an indirect call, it is varying. */ | |
617 if (is_gimple_call (stmt)) | |
618 { | |
619 tree fndecl; | |
620 if (!gimple_call_lhs (stmt) | |
621 || ((fndecl = gimple_call_fndecl (stmt)) != NULL_TREE | |
622 && !DECL_BUILT_IN (fndecl))) | |
623 return true; | |
624 } | |
625 | |
626 /* Anything other than assignments and conditional jumps are not | |
627 interesting for CCP. */ | |
628 if (gimple_code (stmt) != GIMPLE_ASSIGN | |
629 && gimple_code (stmt) != GIMPLE_COND | |
630 && gimple_code (stmt) != GIMPLE_SWITCH | |
631 && gimple_code (stmt) != GIMPLE_CALL) | |
632 return true; | |
633 | |
634 return false; | |
635 } | |
636 | |
637 /* Initialize local data structures for CCP. */ | |
638 | |
639 static void | |
640 ccp_initialize (void) | |
641 { | |
642 basic_block bb; | |
643 | |
644 const_val = XCNEWVEC (prop_value_t, num_ssa_names); | |
645 | |
646 /* Initialize simulation flags for PHI nodes and statements. */ | |
647 FOR_EACH_BB (bb) | |
648 { | |
649 gimple_stmt_iterator i; | |
650 | |
651 for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i)) | |
652 { | |
653 gimple stmt = gsi_stmt (i); | |
654 bool is_varying = surely_varying_stmt_p (stmt); | |
655 | |
656 if (is_varying) | |
657 { | |
658 tree def; | |
659 ssa_op_iter iter; | |
660 | |
661 /* If the statement will not produce a constant, mark | |
662 all its outputs VARYING. */ | |
663 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) | |
664 { | |
665 if (is_varying) | |
666 set_value_varying (def); | |
667 } | |
668 } | |
669 prop_set_simulate_again (stmt, !is_varying); | |
670 } | |
671 } | |
672 | |
673 /* Now process PHI nodes. We never clear the simulate_again flag on | |
674 phi nodes, since we do not know which edges are executable yet, | |
675 except for phi nodes for virtual operands when we do not do store ccp. */ | |
676 FOR_EACH_BB (bb) | |
677 { | |
678 gimple_stmt_iterator i; | |
679 | |
680 for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i)) | |
681 { | |
682 gimple phi = gsi_stmt (i); | |
683 | |
684 if (!is_gimple_reg (gimple_phi_result (phi))) | |
685 prop_set_simulate_again (phi, false); | |
686 else | |
687 prop_set_simulate_again (phi, true); | |
688 } | |
689 } | |
690 } | |
691 | |
692 | |
693 /* Do final substitution of propagated values, cleanup the flowgraph and | |
694 free allocated storage. | |
695 | |
696 Return TRUE when something was optimized. */ | |
697 | |
698 static bool | |
699 ccp_finalize (void) | |
700 { | |
701 /* Perform substitutions based on the known constant values. */ | |
702 bool something_changed = substitute_and_fold (const_val, false); | |
703 | |
704 free (const_val); | |
705 const_val = NULL; | |
706 return something_changed;; | |
707 } | |
708 | |
709 | |
710 /* Compute the meet operator between *VAL1 and *VAL2. Store the result | |
711 in VAL1. | |
712 | |
713 any M UNDEFINED = any | |
714 any M VARYING = VARYING | |
715 Ci M Cj = Ci if (i == j) | |
716 Ci M Cj = VARYING if (i != j) | |
717 */ | |
718 | |
719 static void | |
720 ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2) | |
721 { | |
722 if (val1->lattice_val == UNDEFINED) | |
723 { | |
724 /* UNDEFINED M any = any */ | |
725 *val1 = *val2; | |
726 } | |
727 else if (val2->lattice_val == UNDEFINED) | |
728 { | |
729 /* any M UNDEFINED = any | |
730 Nothing to do. VAL1 already contains the value we want. */ | |
731 ; | |
732 } | |
733 else if (val1->lattice_val == VARYING | |
734 || val2->lattice_val == VARYING) | |
735 { | |
736 /* any M VARYING = VARYING. */ | |
737 val1->lattice_val = VARYING; | |
738 val1->value = NULL_TREE; | |
739 } | |
740 else if (val1->lattice_val == CONSTANT | |
741 && val2->lattice_val == CONSTANT | |
742 && simple_cst_equal (val1->value, val2->value) == 1) | |
743 { | |
744 /* Ci M Cj = Ci if (i == j) | |
745 Ci M Cj = VARYING if (i != j) | |
746 | |
747 If these two values come from memory stores, make sure that | |
748 they come from the same memory reference. */ | |
749 val1->lattice_val = CONSTANT; | |
750 val1->value = val1->value; | |
751 } | |
752 else | |
753 { | |
754 /* Any other combination is VARYING. */ | |
755 val1->lattice_val = VARYING; | |
756 val1->value = NULL_TREE; | |
757 } | |
758 } | |
759 | |
760 | |
761 /* Loop through the PHI_NODE's parameters for BLOCK and compare their | |
762 lattice values to determine PHI_NODE's lattice value. The value of a | |
763 PHI node is determined calling ccp_lattice_meet with all the arguments | |
764 of the PHI node that are incoming via executable edges. */ | |
765 | |
766 static enum ssa_prop_result | |
767 ccp_visit_phi_node (gimple phi) | |
768 { | |
769 unsigned i; | |
770 prop_value_t *old_val, new_val; | |
771 | |
772 if (dump_file && (dump_flags & TDF_DETAILS)) | |
773 { | |
774 fprintf (dump_file, "\nVisiting PHI node: "); | |
775 print_gimple_stmt (dump_file, phi, 0, dump_flags); | |
776 } | |
777 | |
778 old_val = get_value (gimple_phi_result (phi)); | |
779 switch (old_val->lattice_val) | |
780 { | |
781 case VARYING: | |
782 return SSA_PROP_VARYING; | |
783 | |
784 case CONSTANT: | |
785 new_val = *old_val; | |
786 break; | |
787 | |
788 case UNDEFINED: | |
789 new_val.lattice_val = UNDEFINED; | |
790 new_val.value = NULL_TREE; | |
791 break; | |
792 | |
793 default: | |
794 gcc_unreachable (); | |
795 } | |
796 | |
797 for (i = 0; i < gimple_phi_num_args (phi); i++) | |
798 { | |
799 /* Compute the meet operator over all the PHI arguments flowing | |
800 through executable edges. */ | |
801 edge e = gimple_phi_arg_edge (phi, i); | |
802 | |
803 if (dump_file && (dump_flags & TDF_DETAILS)) | |
804 { | |
805 fprintf (dump_file, | |
806 "\n Argument #%d (%d -> %d %sexecutable)\n", | |
807 i, e->src->index, e->dest->index, | |
808 (e->flags & EDGE_EXECUTABLE) ? "" : "not "); | |
809 } | |
810 | |
811 /* If the incoming edge is executable, Compute the meet operator for | |
812 the existing value of the PHI node and the current PHI argument. */ | |
813 if (e->flags & EDGE_EXECUTABLE) | |
814 { | |
815 tree arg = gimple_phi_arg (phi, i)->def; | |
816 prop_value_t arg_val; | |
817 | |
818 if (is_gimple_min_invariant (arg)) | |
819 { | |
820 arg_val.lattice_val = CONSTANT; | |
821 arg_val.value = arg; | |
822 } | |
823 else | |
824 arg_val = *(get_value (arg)); | |
825 | |
826 ccp_lattice_meet (&new_val, &arg_val); | |
827 | |
828 if (dump_file && (dump_flags & TDF_DETAILS)) | |
829 { | |
830 fprintf (dump_file, "\t"); | |
831 print_generic_expr (dump_file, arg, dump_flags); | |
832 dump_lattice_value (dump_file, "\tValue: ", arg_val); | |
833 fprintf (dump_file, "\n"); | |
834 } | |
835 | |
836 if (new_val.lattice_val == VARYING) | |
837 break; | |
838 } | |
839 } | |
840 | |
841 if (dump_file && (dump_flags & TDF_DETAILS)) | |
842 { | |
843 dump_lattice_value (dump_file, "\n PHI node value: ", new_val); | |
844 fprintf (dump_file, "\n\n"); | |
845 } | |
846 | |
847 /* Make the transition to the new value. */ | |
848 if (set_lattice_value (gimple_phi_result (phi), new_val)) | |
849 { | |
850 if (new_val.lattice_val == VARYING) | |
851 return SSA_PROP_VARYING; | |
852 else | |
853 return SSA_PROP_INTERESTING; | |
854 } | |
855 else | |
856 return SSA_PROP_NOT_INTERESTING; | |
857 } | |
858 | |
859 /* Return true if we may propagate the address expression ADDR into the | |
860 dereference DEREF and cancel them. */ | |
861 | |
862 bool | |
863 may_propagate_address_into_dereference (tree addr, tree deref) | |
864 { | |
865 gcc_assert (INDIRECT_REF_P (deref) | |
866 && TREE_CODE (addr) == ADDR_EXPR); | |
867 | |
868 /* Don't propagate if ADDR's operand has incomplete type. */ | |
869 if (!COMPLETE_TYPE_P (TREE_TYPE (TREE_OPERAND (addr, 0)))) | |
870 return false; | |
871 | |
872 /* If the address is invariant then we do not need to preserve restrict | |
873 qualifications. But we do need to preserve volatile qualifiers until | |
874 we can annotate the folded dereference itself properly. */ | |
875 if (is_gimple_min_invariant (addr) | |
876 && (!TREE_THIS_VOLATILE (deref) | |
877 || TYPE_VOLATILE (TREE_TYPE (addr)))) | |
878 return useless_type_conversion_p (TREE_TYPE (deref), | |
879 TREE_TYPE (TREE_OPERAND (addr, 0))); | |
880 | |
881 /* Else both the address substitution and the folding must result in | |
882 a valid useless type conversion sequence. */ | |
883 return (useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (deref, 0)), | |
884 TREE_TYPE (addr)) | |
885 && useless_type_conversion_p (TREE_TYPE (deref), | |
886 TREE_TYPE (TREE_OPERAND (addr, 0)))); | |
887 } | |
888 | |
889 /* CCP specific front-end to the non-destructive constant folding | |
890 routines. | |
891 | |
892 Attempt to simplify the RHS of STMT knowing that one or more | |
893 operands are constants. | |
894 | |
895 If simplification is possible, return the simplified RHS, | |
896 otherwise return the original RHS or NULL_TREE. */ | |
897 | |
898 static tree | |
899 ccp_fold (gimple stmt) | |
900 { | |
901 switch (gimple_code (stmt)) | |
902 { | |
903 case GIMPLE_ASSIGN: | |
904 { | |
905 enum tree_code subcode = gimple_assign_rhs_code (stmt); | |
906 | |
907 switch (get_gimple_rhs_class (subcode)) | |
908 { | |
909 case GIMPLE_SINGLE_RHS: | |
910 { | |
911 tree rhs = gimple_assign_rhs1 (stmt); | |
912 enum tree_code_class kind = TREE_CODE_CLASS (subcode); | |
913 | |
914 if (TREE_CODE (rhs) == SSA_NAME) | |
915 { | |
916 /* If the RHS is an SSA_NAME, return its known constant value, | |
917 if any. */ | |
918 return get_value (rhs)->value; | |
919 } | |
920 /* Handle propagating invariant addresses into address operations. | |
921 The folding we do here matches that in tree-ssa-forwprop.c. */ | |
922 else if (TREE_CODE (rhs) == ADDR_EXPR) | |
923 { | |
924 tree *base; | |
925 base = &TREE_OPERAND (rhs, 0); | |
926 while (handled_component_p (*base)) | |
927 base = &TREE_OPERAND (*base, 0); | |
928 if (TREE_CODE (*base) == INDIRECT_REF | |
929 && TREE_CODE (TREE_OPERAND (*base, 0)) == SSA_NAME) | |
930 { | |
931 prop_value_t *val = get_value (TREE_OPERAND (*base, 0)); | |
932 if (val->lattice_val == CONSTANT | |
933 && TREE_CODE (val->value) == ADDR_EXPR | |
934 && may_propagate_address_into_dereference | |
935 (val->value, *base)) | |
936 { | |
937 /* We need to return a new tree, not modify the IL | |
938 or share parts of it. So play some tricks to | |
939 avoid manually building it. */ | |
940 tree ret, save = *base; | |
941 *base = TREE_OPERAND (val->value, 0); | |
942 ret = unshare_expr (rhs); | |
943 recompute_tree_invariant_for_addr_expr (ret); | |
944 *base = save; | |
945 return ret; | |
946 } | |
947 } | |
948 } | |
949 | |
950 if (kind == tcc_reference) | |
951 { | |
952 if (TREE_CODE (rhs) == VIEW_CONVERT_EXPR | |
953 && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME) | |
954 { | |
955 prop_value_t *val = get_value (TREE_OPERAND (rhs, 0)); | |
956 if (val->lattice_val == CONSTANT) | |
957 return fold_unary (VIEW_CONVERT_EXPR, | |
958 TREE_TYPE (rhs), val->value); | |
959 } | |
960 return fold_const_aggregate_ref (rhs); | |
961 } | |
962 else if (kind == tcc_declaration) | |
963 return get_symbol_constant_value (rhs); | |
964 return rhs; | |
965 } | |
966 | |
967 case GIMPLE_UNARY_RHS: | |
968 { | |
969 /* Handle unary operators that can appear in GIMPLE form. | |
970 Note that we know the single operand must be a constant, | |
971 so this should almost always return a simplified RHS. */ | |
972 tree lhs = gimple_assign_lhs (stmt); | |
973 tree op0 = gimple_assign_rhs1 (stmt); | |
974 | |
975 /* Simplify the operand down to a constant. */ | |
976 if (TREE_CODE (op0) == SSA_NAME) | |
977 { | |
978 prop_value_t *val = get_value (op0); | |
979 if (val->lattice_val == CONSTANT) | |
980 op0 = get_value (op0)->value; | |
981 } | |
982 | |
983 /* Conversions are useless for CCP purposes if they are | |
984 value-preserving. Thus the restrictions that | |
985 useless_type_conversion_p places for pointer type conversions | |
986 do not apply here. Substitution later will only substitute to | |
987 allowed places. */ | |
988 if (CONVERT_EXPR_CODE_P (subcode) | |
989 && POINTER_TYPE_P (TREE_TYPE (lhs)) | |
990 && POINTER_TYPE_P (TREE_TYPE (op0)) | |
991 /* Do not allow differences in volatile qualification | |
992 as this might get us confused as to whether a | |
993 propagation destination statement is volatile | |
994 or not. See PR36988. */ | |
995 && (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (lhs))) | |
996 == TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (op0))))) | |
997 { | |
998 tree tem; | |
999 /* Still try to generate a constant of correct type. */ | |
1000 if (!useless_type_conversion_p (TREE_TYPE (lhs), | |
1001 TREE_TYPE (op0)) | |
1002 && ((tem = maybe_fold_offset_to_address | |
1003 (op0, integer_zero_node, TREE_TYPE (lhs))) | |
1004 != NULL_TREE)) | |
1005 return tem; | |
1006 return op0; | |
1007 } | |
1008 | |
1009 return fold_unary_ignore_overflow (subcode, | |
1010 gimple_expr_type (stmt), op0); | |
1011 } | |
1012 | |
1013 case GIMPLE_BINARY_RHS: | |
1014 { | |
1015 /* Handle binary operators that can appear in GIMPLE form. */ | |
1016 tree op0 = gimple_assign_rhs1 (stmt); | |
1017 tree op1 = gimple_assign_rhs2 (stmt); | |
1018 | |
1019 /* Simplify the operands down to constants when appropriate. */ | |
1020 if (TREE_CODE (op0) == SSA_NAME) | |
1021 { | |
1022 prop_value_t *val = get_value (op0); | |
1023 if (val->lattice_val == CONSTANT) | |
1024 op0 = val->value; | |
1025 } | |
1026 | |
1027 if (TREE_CODE (op1) == SSA_NAME) | |
1028 { | |
1029 prop_value_t *val = get_value (op1); | |
1030 if (val->lattice_val == CONSTANT) | |
1031 op1 = val->value; | |
1032 } | |
1033 | |
1034 /* Fold &foo + CST into an invariant reference if possible. */ | |
1035 if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR | |
1036 && TREE_CODE (op0) == ADDR_EXPR | |
1037 && TREE_CODE (op1) == INTEGER_CST) | |
1038 { | |
1039 tree lhs = gimple_assign_lhs (stmt); | |
1040 tree tem = maybe_fold_offset_to_address (op0, op1, | |
1041 TREE_TYPE (lhs)); | |
1042 if (tem != NULL_TREE) | |
1043 return tem; | |
1044 } | |
1045 | |
1046 return fold_binary (subcode, gimple_expr_type (stmt), op0, op1); | |
1047 } | |
1048 | |
1049 default: | |
1050 gcc_unreachable (); | |
1051 } | |
1052 } | |
1053 break; | |
1054 | |
1055 case GIMPLE_CALL: | |
1056 { | |
1057 tree fn = gimple_call_fn (stmt); | |
1058 prop_value_t *val; | |
1059 | |
1060 if (TREE_CODE (fn) == SSA_NAME) | |
1061 { | |
1062 val = get_value (fn); | |
1063 if (val->lattice_val == CONSTANT) | |
1064 fn = val->value; | |
1065 } | |
1066 if (TREE_CODE (fn) == ADDR_EXPR | |
1067 && TREE_CODE (TREE_OPERAND (fn, 0)) == FUNCTION_DECL | |
1068 && DECL_BUILT_IN (TREE_OPERAND (fn, 0))) | |
1069 { | |
1070 tree *args = XALLOCAVEC (tree, gimple_call_num_args (stmt)); | |
1071 tree call, retval; | |
1072 unsigned i; | |
1073 for (i = 0; i < gimple_call_num_args (stmt); ++i) | |
1074 { | |
1075 args[i] = gimple_call_arg (stmt, i); | |
1076 if (TREE_CODE (args[i]) == SSA_NAME) | |
1077 { | |
1078 val = get_value (args[i]); | |
1079 if (val->lattice_val == CONSTANT) | |
1080 args[i] = val->value; | |
1081 } | |
1082 } | |
1083 call = build_call_array (gimple_call_return_type (stmt), | |
1084 fn, gimple_call_num_args (stmt), args); | |
1085 retval = fold_call_expr (call, false); | |
1086 if (retval) | |
1087 /* fold_call_expr wraps the result inside a NOP_EXPR. */ | |
1088 STRIP_NOPS (retval); | |
1089 return retval; | |
1090 } | |
1091 return NULL_TREE; | |
1092 } | |
1093 | |
1094 case GIMPLE_COND: | |
1095 { | |
1096 /* Handle comparison operators that can appear in GIMPLE form. */ | |
1097 tree op0 = gimple_cond_lhs (stmt); | |
1098 tree op1 = gimple_cond_rhs (stmt); | |
1099 enum tree_code code = gimple_cond_code (stmt); | |
1100 | |
1101 /* Simplify the operands down to constants when appropriate. */ | |
1102 if (TREE_CODE (op0) == SSA_NAME) | |
1103 { | |
1104 prop_value_t *val = get_value (op0); | |
1105 if (val->lattice_val == CONSTANT) | |
1106 op0 = val->value; | |
1107 } | |
1108 | |
1109 if (TREE_CODE (op1) == SSA_NAME) | |
1110 { | |
1111 prop_value_t *val = get_value (op1); | |
1112 if (val->lattice_val == CONSTANT) | |
1113 op1 = val->value; | |
1114 } | |
1115 | |
1116 return fold_binary (code, boolean_type_node, op0, op1); | |
1117 } | |
1118 | |
1119 case GIMPLE_SWITCH: | |
1120 { | |
1121 tree rhs = gimple_switch_index (stmt); | |
1122 | |
1123 if (TREE_CODE (rhs) == SSA_NAME) | |
1124 { | |
1125 /* If the RHS is an SSA_NAME, return its known constant value, | |
1126 if any. */ | |
1127 return get_value (rhs)->value; | |
1128 } | |
1129 | |
1130 return rhs; | |
1131 } | |
1132 | |
1133 default: | |
1134 gcc_unreachable (); | |
1135 } | |
1136 } | |
1137 | |
1138 | |
1139 /* Return the tree representing the element referenced by T if T is an | |
1140 ARRAY_REF or COMPONENT_REF into constant aggregates. Return | |
1141 NULL_TREE otherwise. */ | |
1142 | |
1143 tree | |
1144 fold_const_aggregate_ref (tree t) | |
1145 { | |
1146 prop_value_t *value; | |
1147 tree base, ctor, idx, field; | |
1148 unsigned HOST_WIDE_INT cnt; | |
1149 tree cfield, cval; | |
1150 | |
1151 switch (TREE_CODE (t)) | |
1152 { | |
1153 case ARRAY_REF: | |
1154 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its | |
1155 DECL_INITIAL. If BASE is a nested reference into another | |
1156 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve | |
1157 the inner reference. */ | |
1158 base = TREE_OPERAND (t, 0); | |
1159 switch (TREE_CODE (base)) | |
1160 { | |
1161 case VAR_DECL: | |
1162 if (!TREE_READONLY (base) | |
1163 || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE | |
1164 || !targetm.binds_local_p (base)) | |
1165 return NULL_TREE; | |
1166 | |
1167 ctor = DECL_INITIAL (base); | |
1168 break; | |
1169 | |
1170 case ARRAY_REF: | |
1171 case COMPONENT_REF: | |
1172 ctor = fold_const_aggregate_ref (base); | |
1173 break; | |
1174 | |
1175 case STRING_CST: | |
1176 case CONSTRUCTOR: | |
1177 ctor = base; | |
1178 break; | |
1179 | |
1180 default: | |
1181 return NULL_TREE; | |
1182 } | |
1183 | |
1184 if (ctor == NULL_TREE | |
1185 || (TREE_CODE (ctor) != CONSTRUCTOR | |
1186 && TREE_CODE (ctor) != STRING_CST) | |
1187 || !TREE_STATIC (ctor)) | |
1188 return NULL_TREE; | |
1189 | |
1190 /* Get the index. If we have an SSA_NAME, try to resolve it | |
1191 with the current lattice value for the SSA_NAME. */ | |
1192 idx = TREE_OPERAND (t, 1); | |
1193 switch (TREE_CODE (idx)) | |
1194 { | |
1195 case SSA_NAME: | |
1196 if ((value = get_value (idx)) | |
1197 && value->lattice_val == CONSTANT | |
1198 && TREE_CODE (value->value) == INTEGER_CST) | |
1199 idx = value->value; | |
1200 else | |
1201 return NULL_TREE; | |
1202 break; | |
1203 | |
1204 case INTEGER_CST: | |
1205 break; | |
1206 | |
1207 default: | |
1208 return NULL_TREE; | |
1209 } | |
1210 | |
1211 /* Fold read from constant string. */ | |
1212 if (TREE_CODE (ctor) == STRING_CST) | |
1213 { | |
1214 if ((TYPE_MODE (TREE_TYPE (t)) | |
1215 == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) | |
1216 && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) | |
1217 == MODE_INT) | |
1218 && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1 | |
1219 && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0) | |
1220 return build_int_cst_type (TREE_TYPE (t), | |
1221 (TREE_STRING_POINTER (ctor) | |
1222 [TREE_INT_CST_LOW (idx)])); | |
1223 return NULL_TREE; | |
1224 } | |
1225 | |
1226 /* Whoo-hoo! I'll fold ya baby. Yeah! */ | |
1227 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval) | |
1228 if (tree_int_cst_equal (cfield, idx)) | |
1229 { | |
1230 STRIP_USELESS_TYPE_CONVERSION (cval); | |
1231 return cval; | |
1232 } | |
1233 break; | |
1234 | |
1235 case COMPONENT_REF: | |
1236 /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its | |
1237 DECL_INITIAL. If BASE is a nested reference into another | |
1238 ARRAY_REF or COMPONENT_REF, make a recursive call to resolve | |
1239 the inner reference. */ | |
1240 base = TREE_OPERAND (t, 0); | |
1241 switch (TREE_CODE (base)) | |
1242 { | |
1243 case VAR_DECL: | |
1244 if (!TREE_READONLY (base) | |
1245 || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE | |
1246 || !targetm.binds_local_p (base)) | |
1247 return NULL_TREE; | |
1248 | |
1249 ctor = DECL_INITIAL (base); | |
1250 break; | |
1251 | |
1252 case ARRAY_REF: | |
1253 case COMPONENT_REF: | |
1254 ctor = fold_const_aggregate_ref (base); | |
1255 break; | |
1256 | |
1257 default: | |
1258 return NULL_TREE; | |
1259 } | |
1260 | |
1261 if (ctor == NULL_TREE | |
1262 || TREE_CODE (ctor) != CONSTRUCTOR | |
1263 || !TREE_STATIC (ctor)) | |
1264 return NULL_TREE; | |
1265 | |
1266 field = TREE_OPERAND (t, 1); | |
1267 | |
1268 FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval) | |
1269 if (cfield == field | |
1270 /* FIXME: Handle bit-fields. */ | |
1271 && ! DECL_BIT_FIELD (cfield)) | |
1272 { | |
1273 STRIP_USELESS_TYPE_CONVERSION (cval); | |
1274 return cval; | |
1275 } | |
1276 break; | |
1277 | |
1278 case REALPART_EXPR: | |
1279 case IMAGPART_EXPR: | |
1280 { | |
1281 tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0)); | |
1282 if (c && TREE_CODE (c) == COMPLEX_CST) | |
1283 return fold_build1 (TREE_CODE (t), TREE_TYPE (t), c); | |
1284 break; | |
1285 } | |
1286 | |
1287 case INDIRECT_REF: | |
1288 { | |
1289 tree base = TREE_OPERAND (t, 0); | |
1290 if (TREE_CODE (base) == SSA_NAME | |
1291 && (value = get_value (base)) | |
1292 && value->lattice_val == CONSTANT | |
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kent@firefly.cr.ie.u-ryukyu.ac.jp
parents:
0
diff
changeset
|
1293 && TREE_CODE (value->value) == ADDR_EXPR |
58ad6c70ea60
update gcc from 4.4.0 to 4.4.1.
kent@firefly.cr.ie.u-ryukyu.ac.jp
parents:
0
diff
changeset
|
1294 && useless_type_conversion_p (TREE_TYPE (t), |
58ad6c70ea60
update gcc from 4.4.0 to 4.4.1.
kent@firefly.cr.ie.u-ryukyu.ac.jp
parents:
0
diff
changeset
|
1295 TREE_TYPE (TREE_TYPE (value->value)))) |
0 | 1296 return fold_const_aggregate_ref (TREE_OPERAND (value->value, 0)); |
1297 break; | |
1298 } | |
1299 | |
1300 default: | |
1301 break; | |
1302 } | |
1303 | |
1304 return NULL_TREE; | |
1305 } | |
1306 | |
1307 /* Evaluate statement STMT. | |
1308 Valid only for assignments, calls, conditionals, and switches. */ | |
1309 | |
1310 static prop_value_t | |
1311 evaluate_stmt (gimple stmt) | |
1312 { | |
1313 prop_value_t val; | |
1314 tree simplified = NULL_TREE; | |
1315 ccp_lattice_t likelyvalue = likely_value (stmt); | |
1316 bool is_constant; | |
1317 | |
1318 fold_defer_overflow_warnings (); | |
1319 | |
1320 /* If the statement is likely to have a CONSTANT result, then try | |
1321 to fold the statement to determine the constant value. */ | |
1322 /* FIXME. This is the only place that we call ccp_fold. | |
1323 Since likely_value never returns CONSTANT for calls, we will | |
1324 not attempt to fold them, including builtins that may profit. */ | |
1325 if (likelyvalue == CONSTANT) | |
1326 simplified = ccp_fold (stmt); | |
1327 /* If the statement is likely to have a VARYING result, then do not | |
1328 bother folding the statement. */ | |
1329 else if (likelyvalue == VARYING) | |
1330 { | |
1331 enum gimple_code code = gimple_code (stmt); | |
1332 if (code == GIMPLE_ASSIGN) | |
1333 { | |
1334 enum tree_code subcode = gimple_assign_rhs_code (stmt); | |
1335 | |
1336 /* Other cases cannot satisfy is_gimple_min_invariant | |
1337 without folding. */ | |
1338 if (get_gimple_rhs_class (subcode) == GIMPLE_SINGLE_RHS) | |
1339 simplified = gimple_assign_rhs1 (stmt); | |
1340 } | |
1341 else if (code == GIMPLE_SWITCH) | |
1342 simplified = gimple_switch_index (stmt); | |
1343 else | |
1344 /* These cannot satisfy is_gimple_min_invariant without folding. */ | |
1345 gcc_assert (code == GIMPLE_CALL || code == GIMPLE_COND); | |
1346 } | |
1347 | |
1348 is_constant = simplified && is_gimple_min_invariant (simplified); | |
1349 | |
1350 fold_undefer_overflow_warnings (is_constant, stmt, 0); | |
1351 | |
1352 if (dump_file && (dump_flags & TDF_DETAILS)) | |
1353 { | |
1354 fprintf (dump_file, "which is likely "); | |
1355 switch (likelyvalue) | |
1356 { | |
1357 case CONSTANT: | |
1358 fprintf (dump_file, "CONSTANT"); | |
1359 break; | |
1360 case UNDEFINED: | |
1361 fprintf (dump_file, "UNDEFINED"); | |
1362 break; | |
1363 case VARYING: | |
1364 fprintf (dump_file, "VARYING"); | |
1365 break; | |
1366 default:; | |
1367 } | |
1368 fprintf (dump_file, "\n"); | |
1369 } | |
1370 | |
1371 if (is_constant) | |
1372 { | |
1373 /* The statement produced a constant value. */ | |
1374 val.lattice_val = CONSTANT; | |
1375 val.value = simplified; | |
1376 } | |
1377 else | |
1378 { | |
1379 /* The statement produced a nonconstant value. If the statement | |
1380 had UNDEFINED operands, then the result of the statement | |
1381 should be UNDEFINED. Otherwise, the statement is VARYING. */ | |
1382 if (likelyvalue == UNDEFINED) | |
1383 val.lattice_val = likelyvalue; | |
1384 else | |
1385 val.lattice_val = VARYING; | |
1386 | |
1387 val.value = NULL_TREE; | |
1388 } | |
1389 | |
1390 return val; | |
1391 } | |
1392 | |
1393 /* Visit the assignment statement STMT. Set the value of its LHS to the | |
1394 value computed by the RHS and store LHS in *OUTPUT_P. If STMT | |
1395 creates virtual definitions, set the value of each new name to that | |
1396 of the RHS (if we can derive a constant out of the RHS). | |
1397 Value-returning call statements also perform an assignment, and | |
1398 are handled here. */ | |
1399 | |
1400 static enum ssa_prop_result | |
1401 visit_assignment (gimple stmt, tree *output_p) | |
1402 { | |
1403 prop_value_t val; | |
1404 enum ssa_prop_result retval; | |
1405 | |
1406 tree lhs = gimple_get_lhs (stmt); | |
1407 | |
1408 gcc_assert (gimple_code (stmt) != GIMPLE_CALL | |
1409 || gimple_call_lhs (stmt) != NULL_TREE); | |
1410 | |
1411 if (gimple_assign_copy_p (stmt)) | |
1412 { | |
1413 tree rhs = gimple_assign_rhs1 (stmt); | |
1414 | |
1415 if (TREE_CODE (rhs) == SSA_NAME) | |
1416 { | |
1417 /* For a simple copy operation, we copy the lattice values. */ | |
1418 prop_value_t *nval = get_value (rhs); | |
1419 val = *nval; | |
1420 } | |
1421 else | |
1422 val = evaluate_stmt (stmt); | |
1423 } | |
1424 else | |
1425 /* Evaluate the statement, which could be | |
1426 either a GIMPLE_ASSIGN or a GIMPLE_CALL. */ | |
1427 val = evaluate_stmt (stmt); | |
1428 | |
1429 retval = SSA_PROP_NOT_INTERESTING; | |
1430 | |
1431 /* Set the lattice value of the statement's output. */ | |
1432 if (TREE_CODE (lhs) == SSA_NAME) | |
1433 { | |
1434 /* If STMT is an assignment to an SSA_NAME, we only have one | |
1435 value to set. */ | |
1436 if (set_lattice_value (lhs, val)) | |
1437 { | |
1438 *output_p = lhs; | |
1439 if (val.lattice_val == VARYING) | |
1440 retval = SSA_PROP_VARYING; | |
1441 else | |
1442 retval = SSA_PROP_INTERESTING; | |
1443 } | |
1444 } | |
1445 | |
1446 return retval; | |
1447 } | |
1448 | |
1449 | |
1450 /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING | |
1451 if it can determine which edge will be taken. Otherwise, return | |
1452 SSA_PROP_VARYING. */ | |
1453 | |
1454 static enum ssa_prop_result | |
1455 visit_cond_stmt (gimple stmt, edge *taken_edge_p) | |
1456 { | |
1457 prop_value_t val; | |
1458 basic_block block; | |
1459 | |
1460 block = gimple_bb (stmt); | |
1461 val = evaluate_stmt (stmt); | |
1462 | |
1463 /* Find which edge out of the conditional block will be taken and add it | |
1464 to the worklist. If no single edge can be determined statically, | |
1465 return SSA_PROP_VARYING to feed all the outgoing edges to the | |
1466 propagation engine. */ | |
1467 *taken_edge_p = val.value ? find_taken_edge (block, val.value) : 0; | |
1468 if (*taken_edge_p) | |
1469 return SSA_PROP_INTERESTING; | |
1470 else | |
1471 return SSA_PROP_VARYING; | |
1472 } | |
1473 | |
1474 | |
1475 /* Evaluate statement STMT. If the statement produces an output value and | |
1476 its evaluation changes the lattice value of its output, return | |
1477 SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the | |
1478 output value. | |
1479 | |
1480 If STMT is a conditional branch and we can determine its truth | |
1481 value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying | |
1482 value, return SSA_PROP_VARYING. */ | |
1483 | |
1484 static enum ssa_prop_result | |
1485 ccp_visit_stmt (gimple stmt, edge *taken_edge_p, tree *output_p) | |
1486 { | |
1487 tree def; | |
1488 ssa_op_iter iter; | |
1489 | |
1490 if (dump_file && (dump_flags & TDF_DETAILS)) | |
1491 { | |
1492 fprintf (dump_file, "\nVisiting statement:\n"); | |
1493 print_gimple_stmt (dump_file, stmt, 0, dump_flags); | |
1494 } | |
1495 | |
1496 switch (gimple_code (stmt)) | |
1497 { | |
1498 case GIMPLE_ASSIGN: | |
1499 /* If the statement is an assignment that produces a single | |
1500 output value, evaluate its RHS to see if the lattice value of | |
1501 its output has changed. */ | |
1502 return visit_assignment (stmt, output_p); | |
1503 | |
1504 case GIMPLE_CALL: | |
1505 /* A value-returning call also performs an assignment. */ | |
1506 if (gimple_call_lhs (stmt) != NULL_TREE) | |
1507 return visit_assignment (stmt, output_p); | |
1508 break; | |
1509 | |
1510 case GIMPLE_COND: | |
1511 case GIMPLE_SWITCH: | |
1512 /* If STMT is a conditional branch, see if we can determine | |
1513 which branch will be taken. */ | |
1514 /* FIXME. It appears that we should be able to optimize | |
1515 computed GOTOs here as well. */ | |
1516 return visit_cond_stmt (stmt, taken_edge_p); | |
1517 | |
1518 default: | |
1519 break; | |
1520 } | |
1521 | |
1522 /* Any other kind of statement is not interesting for constant | |
1523 propagation and, therefore, not worth simulating. */ | |
1524 if (dump_file && (dump_flags & TDF_DETAILS)) | |
1525 fprintf (dump_file, "No interesting values produced. Marked VARYING.\n"); | |
1526 | |
1527 /* Definitions made by statements other than assignments to | |
1528 SSA_NAMEs represent unknown modifications to their outputs. | |
1529 Mark them VARYING. */ | |
1530 FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) | |
1531 { | |
1532 prop_value_t v = { VARYING, NULL_TREE }; | |
1533 set_lattice_value (def, v); | |
1534 } | |
1535 | |
1536 return SSA_PROP_VARYING; | |
1537 } | |
1538 | |
1539 | |
1540 /* Main entry point for SSA Conditional Constant Propagation. */ | |
1541 | |
1542 static unsigned int | |
1543 do_ssa_ccp (void) | |
1544 { | |
1545 ccp_initialize (); | |
1546 ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node); | |
1547 if (ccp_finalize ()) | |
1548 return (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals); | |
1549 else | |
1550 return 0; | |
1551 } | |
1552 | |
1553 | |
1554 static bool | |
1555 gate_ccp (void) | |
1556 { | |
1557 return flag_tree_ccp != 0; | |
1558 } | |
1559 | |
1560 | |
1561 struct gimple_opt_pass pass_ccp = | |
1562 { | |
1563 { | |
1564 GIMPLE_PASS, | |
1565 "ccp", /* name */ | |
1566 gate_ccp, /* gate */ | |
1567 do_ssa_ccp, /* execute */ | |
1568 NULL, /* sub */ | |
1569 NULL, /* next */ | |
1570 0, /* static_pass_number */ | |
1571 TV_TREE_CCP, /* tv_id */ | |
1572 PROP_cfg | PROP_ssa, /* properties_required */ | |
1573 0, /* properties_provided */ | |
1574 0, /* properties_destroyed */ | |
1575 0, /* todo_flags_start */ | |
1576 TODO_dump_func | TODO_verify_ssa | |
1577 | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */ | |
1578 } | |
1579 }; | |
1580 | |
1581 | |
1582 /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X]. | |
1583 BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE | |
1584 is the desired result type. */ | |
1585 | |
1586 static tree | |
1587 maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type, | |
1588 bool allow_negative_idx) | |
1589 { | |
1590 tree min_idx, idx, idx_type, elt_offset = integer_zero_node; | |
1591 tree array_type, elt_type, elt_size; | |
1592 tree domain_type; | |
1593 | |
1594 /* If BASE is an ARRAY_REF, we can pick up another offset (this time | |
1595 measured in units of the size of elements type) from that ARRAY_REF). | |
1596 We can't do anything if either is variable. | |
1597 | |
1598 The case we handle here is *(&A[N]+O). */ | |
1599 if (TREE_CODE (base) == ARRAY_REF) | |
1600 { | |
1601 tree low_bound = array_ref_low_bound (base); | |
1602 | |
1603 elt_offset = TREE_OPERAND (base, 1); | |
1604 if (TREE_CODE (low_bound) != INTEGER_CST | |
1605 || TREE_CODE (elt_offset) != INTEGER_CST) | |
1606 return NULL_TREE; | |
1607 | |
1608 elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0); | |
1609 base = TREE_OPERAND (base, 0); | |
1610 } | |
1611 | |
1612 /* Ignore stupid user tricks of indexing non-array variables. */ | |
1613 array_type = TREE_TYPE (base); | |
1614 if (TREE_CODE (array_type) != ARRAY_TYPE) | |
1615 return NULL_TREE; | |
1616 elt_type = TREE_TYPE (array_type); | |
1617 if (!useless_type_conversion_p (orig_type, elt_type)) | |
1618 return NULL_TREE; | |
1619 | |
1620 /* Use signed size type for intermediate computation on the index. */ | |
1621 idx_type = signed_type_for (size_type_node); | |
1622 | |
1623 /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the | |
1624 element type (so we can use the alignment if it's not constant). | |
1625 Otherwise, compute the offset as an index by using a division. If the | |
1626 division isn't exact, then don't do anything. */ | |
1627 elt_size = TYPE_SIZE_UNIT (elt_type); | |
1628 if (!elt_size) | |
1629 return NULL; | |
1630 if (integer_zerop (offset)) | |
1631 { | |
1632 if (TREE_CODE (elt_size) != INTEGER_CST) | |
1633 elt_size = size_int (TYPE_ALIGN (elt_type)); | |
1634 | |
1635 idx = build_int_cst (idx_type, 0); | |
1636 } | |
1637 else | |
1638 { | |
1639 unsigned HOST_WIDE_INT lquo, lrem; | |
1640 HOST_WIDE_INT hquo, hrem; | |
1641 double_int soffset; | |
1642 | |
1643 /* The final array offset should be signed, so we need | |
1644 to sign-extend the (possibly pointer) offset here | |
1645 and use signed division. */ | |
1646 soffset = double_int_sext (tree_to_double_int (offset), | |
1647 TYPE_PRECISION (TREE_TYPE (offset))); | |
1648 if (TREE_CODE (elt_size) != INTEGER_CST | |
1649 || div_and_round_double (TRUNC_DIV_EXPR, 0, | |
1650 soffset.low, soffset.high, | |
1651 TREE_INT_CST_LOW (elt_size), | |
1652 TREE_INT_CST_HIGH (elt_size), | |
1653 &lquo, &hquo, &lrem, &hrem) | |
1654 || lrem || hrem) | |
1655 return NULL_TREE; | |
1656 | |
1657 idx = build_int_cst_wide (idx_type, lquo, hquo); | |
1658 } | |
1659 | |
1660 /* Assume the low bound is zero. If there is a domain type, get the | |
1661 low bound, if any, convert the index into that type, and add the | |
1662 low bound. */ | |
1663 min_idx = build_int_cst (idx_type, 0); | |
1664 domain_type = TYPE_DOMAIN (array_type); | |
1665 if (domain_type) | |
1666 { | |
1667 idx_type = domain_type; | |
1668 if (TYPE_MIN_VALUE (idx_type)) | |
1669 min_idx = TYPE_MIN_VALUE (idx_type); | |
1670 else | |
1671 min_idx = fold_convert (idx_type, min_idx); | |
1672 | |
1673 if (TREE_CODE (min_idx) != INTEGER_CST) | |
1674 return NULL_TREE; | |
1675 | |
1676 elt_offset = fold_convert (idx_type, elt_offset); | |
1677 } | |
1678 | |
1679 if (!integer_zerop (min_idx)) | |
1680 idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0); | |
1681 if (!integer_zerop (elt_offset)) | |
1682 idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0); | |
1683 | |
1684 /* Make sure to possibly truncate late after offsetting. */ | |
1685 idx = fold_convert (idx_type, idx); | |
1686 | |
1687 /* We don't want to construct access past array bounds. For example | |
1688 char *(c[4]); | |
1689 c[3][2]; | |
1690 should not be simplified into (*c)[14] or tree-vrp will | |
1691 give false warnings. The same is true for | |
1692 struct A { long x; char d[0]; } *a; | |
1693 (char *)a - 4; | |
1694 which should be not folded to &a->d[-8]. */ | |
1695 if (domain_type | |
1696 && TYPE_MAX_VALUE (domain_type) | |
1697 && TREE_CODE (TYPE_MAX_VALUE (domain_type)) == INTEGER_CST) | |
1698 { | |
1699 tree up_bound = TYPE_MAX_VALUE (domain_type); | |
1700 | |
1701 if (tree_int_cst_lt (up_bound, idx) | |
1702 /* Accesses after the end of arrays of size 0 (gcc | |
1703 extension) and 1 are likely intentional ("struct | |
1704 hack"). */ | |
1705 && compare_tree_int (up_bound, 1) > 0) | |
1706 return NULL_TREE; | |
1707 } | |
1708 if (domain_type | |
1709 && TYPE_MIN_VALUE (domain_type)) | |
1710 { | |
1711 if (!allow_negative_idx | |
1712 && TREE_CODE (TYPE_MIN_VALUE (domain_type)) == INTEGER_CST | |
1713 && tree_int_cst_lt (idx, TYPE_MIN_VALUE (domain_type))) | |
1714 return NULL_TREE; | |
1715 } | |
1716 else if (!allow_negative_idx | |
1717 && compare_tree_int (idx, 0) < 0) | |
1718 return NULL_TREE; | |
1719 | |
1720 return build4 (ARRAY_REF, elt_type, base, idx, NULL_TREE, NULL_TREE); | |
1721 } | |
1722 | |
1723 | |
1724 /* Attempt to fold *(S+O) to S.X. | |
1725 BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE | |
1726 is the desired result type. */ | |
1727 | |
1728 static tree | |
1729 maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset, | |
47
3bfb6c00c1e0
update it from 4.4.2 to 4.4.3.
kent <kent@cr.ie.u-ryukyu.ac.jp>
parents:
19
diff
changeset
|
1730 tree orig_type) |
0 | 1731 { |
1732 tree f, t, field_type, tail_array_field, field_offset; | |
1733 tree ret; | |
1734 tree new_base; | |
1735 | |
1736 if (TREE_CODE (record_type) != RECORD_TYPE | |
1737 && TREE_CODE (record_type) != UNION_TYPE | |
1738 && TREE_CODE (record_type) != QUAL_UNION_TYPE) | |
1739 return NULL_TREE; | |
1740 | |
1741 /* Short-circuit silly cases. */ | |
1742 if (useless_type_conversion_p (record_type, orig_type)) | |
1743 return NULL_TREE; | |
1744 | |
1745 tail_array_field = NULL_TREE; | |
1746 for (f = TYPE_FIELDS (record_type); f ; f = TREE_CHAIN (f)) | |
1747 { | |
1748 int cmp; | |
1749 | |
1750 if (TREE_CODE (f) != FIELD_DECL) | |
1751 continue; | |
1752 if (DECL_BIT_FIELD (f)) | |
1753 continue; | |
1754 | |
1755 if (!DECL_FIELD_OFFSET (f)) | |
1756 continue; | |
1757 field_offset = byte_position (f); | |
1758 if (TREE_CODE (field_offset) != INTEGER_CST) | |
1759 continue; | |
1760 | |
1761 /* ??? Java creates "interesting" fields for representing base classes. | |
1762 They have no name, and have no context. With no context, we get into | |
1763 trouble with nonoverlapping_component_refs_p. Skip them. */ | |
1764 if (!DECL_FIELD_CONTEXT (f)) | |
1765 continue; | |
1766 | |
1767 /* The previous array field isn't at the end. */ | |
1768 tail_array_field = NULL_TREE; | |
1769 | |
1770 /* Check to see if this offset overlaps with the field. */ | |
1771 cmp = tree_int_cst_compare (field_offset, offset); | |
1772 if (cmp > 0) | |
1773 continue; | |
1774 | |
1775 field_type = TREE_TYPE (f); | |
1776 | |
1777 /* Here we exactly match the offset being checked. If the types match, | |
1778 then we can return that field. */ | |
1779 if (cmp == 0 | |
1780 && useless_type_conversion_p (orig_type, field_type)) | |
1781 { | |
1782 t = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE); | |
1783 return t; | |
1784 } | |
1785 | |
1786 /* Don't care about offsets into the middle of scalars. */ | |
1787 if (!AGGREGATE_TYPE_P (field_type)) | |
1788 continue; | |
1789 | |
1790 /* Check for array at the end of the struct. This is often | |
1791 used as for flexible array members. We should be able to | |
1792 turn this into an array access anyway. */ | |
1793 if (TREE_CODE (field_type) == ARRAY_TYPE) | |
1794 tail_array_field = f; | |
1795 | |
1796 /* Check the end of the field against the offset. */ | |
1797 if (!DECL_SIZE_UNIT (f) | |
1798 || TREE_CODE (DECL_SIZE_UNIT (f)) != INTEGER_CST) | |
1799 continue; | |
1800 t = int_const_binop (MINUS_EXPR, offset, field_offset, 1); | |
1801 if (!tree_int_cst_lt (t, DECL_SIZE_UNIT (f))) | |
1802 continue; | |
1803 | |
1804 /* If we matched, then set offset to the displacement into | |
1805 this field. */ | |
47
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1806 new_base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE); |
0 | 1807 |
1808 /* Recurse to possibly find the match. */ | |
1809 ret = maybe_fold_offset_to_array_ref (new_base, t, orig_type, | |
1810 f == TYPE_FIELDS (record_type)); | |
1811 if (ret) | |
1812 return ret; | |
1813 ret = maybe_fold_offset_to_component_ref (field_type, new_base, t, | |
47
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1814 orig_type); |
0 | 1815 if (ret) |
1816 return ret; | |
1817 } | |
1818 | |
1819 if (!tail_array_field) | |
1820 return NULL_TREE; | |
1821 | |
1822 f = tail_array_field; | |
1823 field_type = TREE_TYPE (f); | |
1824 offset = int_const_binop (MINUS_EXPR, offset, byte_position (f), 1); | |
1825 | |
1826 /* If we get here, we've got an aggregate field, and a possibly | |
1827 nonzero offset into them. Recurse and hope for a valid match. */ | |
1828 base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE); | |
1829 | |
1830 t = maybe_fold_offset_to_array_ref (base, offset, orig_type, | |
1831 f == TYPE_FIELDS (record_type)); | |
1832 if (t) | |
1833 return t; | |
1834 return maybe_fold_offset_to_component_ref (field_type, base, offset, | |
47
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1835 orig_type); |
0 | 1836 } |
1837 | |
1838 /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE->field_of_orig_type | |
1839 or BASE[index] or by combination of those. | |
1840 | |
1841 Before attempting the conversion strip off existing ADDR_EXPRs and | |
1842 handled component refs. */ | |
1843 | |
1844 tree | |
1845 maybe_fold_offset_to_reference (tree base, tree offset, tree orig_type) | |
1846 { | |
1847 tree ret; | |
1848 tree type; | |
1849 | |
1850 STRIP_NOPS (base); | |
47
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1851 if (TREE_CODE (base) != ADDR_EXPR) |
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1852 return NULL_TREE; |
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1853 |
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1854 base = TREE_OPERAND (base, 0); |
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1855 |
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1856 /* Handle case where existing COMPONENT_REF pick e.g. wrong field of union, |
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1857 so it needs to be removed and new COMPONENT_REF constructed. |
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1858 The wrong COMPONENT_REF are often constructed by folding the |
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1859 (type *)&object within the expression (type *)&object+offset */ |
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1860 if (handled_component_p (base)) |
0 | 1861 { |
47
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1862 HOST_WIDE_INT sub_offset, size, maxsize; |
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1863 tree newbase; |
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1864 newbase = get_ref_base_and_extent (base, &sub_offset, |
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1865 &size, &maxsize); |
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1866 gcc_assert (newbase); |
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1867 if (size == maxsize |
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1868 && size != -1 |
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1869 && !(sub_offset & (BITS_PER_UNIT - 1))) |
0 | 1870 { |
47
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1871 base = newbase; |
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1872 if (sub_offset) |
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1873 offset = int_const_binop (PLUS_EXPR, offset, |
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1874 build_int_cst (TREE_TYPE (offset), |
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1875 sub_offset / BITS_PER_UNIT), 1); |
0 | 1876 } |
1877 } | |
47
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1878 if (useless_type_conversion_p (orig_type, TREE_TYPE (base)) |
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1879 && integer_zerop (offset)) |
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1880 return base; |
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1881 type = TREE_TYPE (base); |
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1882 |
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1883 ret = maybe_fold_offset_to_component_ref (type, base, offset, orig_type); |
0 | 1884 if (!ret) |
47
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1885 ret = maybe_fold_offset_to_array_ref (base, offset, orig_type, true); |
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1886 |
0 | 1887 return ret; |
1888 } | |
1889 | |
1890 /* Attempt to express (ORIG_TYPE)&BASE+OFFSET as &BASE->field_of_orig_type | |
1891 or &BASE[index] or by combination of those. | |
1892 | |
1893 Before attempting the conversion strip off existing component refs. */ | |
1894 | |
1895 tree | |
1896 maybe_fold_offset_to_address (tree addr, tree offset, tree orig_type) | |
1897 { | |
1898 tree t; | |
1899 | |
1900 gcc_assert (POINTER_TYPE_P (TREE_TYPE (addr)) | |
1901 && POINTER_TYPE_P (orig_type)); | |
1902 | |
1903 t = maybe_fold_offset_to_reference (addr, offset, TREE_TYPE (orig_type)); | |
1904 if (t != NULL_TREE) | |
1905 { | |
1906 tree orig = addr; | |
1907 tree ptr_type; | |
1908 | |
1909 /* For __builtin_object_size to function correctly we need to | |
1910 make sure not to fold address arithmetic so that we change | |
1911 reference from one array to another. This would happen for | |
1912 example for | |
1913 | |
1914 struct X { char s1[10]; char s2[10] } s; | |
1915 char *foo (void) { return &s.s2[-4]; } | |
1916 | |
1917 where we need to avoid generating &s.s1[6]. As the C and | |
1918 C++ frontends create different initial trees | |
1919 (char *) &s.s1 + -4 vs. &s.s1[-4] we have to do some | |
1920 sophisticated comparisons here. Note that checking for the | |
1921 condition after the fact is easier than trying to avoid doing | |
1922 the folding. */ | |
1923 STRIP_NOPS (orig); | |
1924 if (TREE_CODE (orig) == ADDR_EXPR) | |
1925 orig = TREE_OPERAND (orig, 0); | |
1926 if ((TREE_CODE (orig) == ARRAY_REF | |
1927 || (TREE_CODE (orig) == COMPONENT_REF | |
1928 && TREE_CODE (TREE_TYPE (TREE_OPERAND (orig, 1))) == ARRAY_TYPE)) | |
1929 && (TREE_CODE (t) == ARRAY_REF | |
1930 || TREE_CODE (t) == COMPONENT_REF) | |
1931 && !operand_equal_p (TREE_CODE (orig) == ARRAY_REF | |
1932 ? TREE_OPERAND (orig, 0) : orig, | |
1933 TREE_CODE (t) == ARRAY_REF | |
1934 ? TREE_OPERAND (t, 0) : t, 0)) | |
1935 return NULL_TREE; | |
1936 | |
1937 ptr_type = build_pointer_type (TREE_TYPE (t)); | |
1938 if (!useless_type_conversion_p (orig_type, ptr_type)) | |
1939 return NULL_TREE; | |
1940 return build_fold_addr_expr_with_type (t, ptr_type); | |
1941 } | |
1942 | |
1943 return NULL_TREE; | |
1944 } | |
1945 | |
1946 /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET). | |
1947 Return the simplified expression, or NULL if nothing could be done. */ | |
1948 | |
1949 static tree | |
1950 maybe_fold_stmt_indirect (tree expr, tree base, tree offset) | |
1951 { | |
1952 tree t; | |
1953 bool volatile_p = TREE_THIS_VOLATILE (expr); | |
1954 | |
1955 /* We may well have constructed a double-nested PLUS_EXPR via multiple | |
1956 substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that | |
1957 are sometimes added. */ | |
1958 base = fold (base); | |
1959 STRIP_TYPE_NOPS (base); | |
1960 TREE_OPERAND (expr, 0) = base; | |
1961 | |
1962 /* One possibility is that the address reduces to a string constant. */ | |
1963 t = fold_read_from_constant_string (expr); | |
1964 if (t) | |
1965 return t; | |
1966 | |
1967 /* Add in any offset from a POINTER_PLUS_EXPR. */ | |
1968 if (TREE_CODE (base) == POINTER_PLUS_EXPR) | |
1969 { | |
1970 tree offset2; | |
1971 | |
1972 offset2 = TREE_OPERAND (base, 1); | |
1973 if (TREE_CODE (offset2) != INTEGER_CST) | |
1974 return NULL_TREE; | |
1975 base = TREE_OPERAND (base, 0); | |
1976 | |
1977 offset = fold_convert (sizetype, | |
1978 int_const_binop (PLUS_EXPR, offset, offset2, 1)); | |
1979 } | |
1980 | |
1981 if (TREE_CODE (base) == ADDR_EXPR) | |
1982 { | |
1983 tree base_addr = base; | |
1984 | |
1985 /* Strip the ADDR_EXPR. */ | |
1986 base = TREE_OPERAND (base, 0); | |
1987 | |
1988 /* Fold away CONST_DECL to its value, if the type is scalar. */ | |
1989 if (TREE_CODE (base) == CONST_DECL | |
1990 && is_gimple_min_invariant (DECL_INITIAL (base))) | |
1991 return DECL_INITIAL (base); | |
1992 | |
1993 /* Try folding *(&B+O) to B.X. */ | |
1994 t = maybe_fold_offset_to_reference (base_addr, offset, | |
1995 TREE_TYPE (expr)); | |
1996 if (t) | |
1997 { | |
1998 /* Preserve volatileness of the original expression. | |
1999 We can end up with a plain decl here which is shared | |
2000 and we shouldn't mess with its flags. */ | |
2001 if (!SSA_VAR_P (t)) | |
2002 TREE_THIS_VOLATILE (t) = volatile_p; | |
2003 return t; | |
2004 } | |
2005 } | |
2006 else | |
2007 { | |
2008 /* We can get here for out-of-range string constant accesses, | |
2009 such as "_"[3]. Bail out of the entire substitution search | |
2010 and arrange for the entire statement to be replaced by a | |
2011 call to __builtin_trap. In all likelihood this will all be | |
2012 constant-folded away, but in the meantime we can't leave with | |
2013 something that get_expr_operands can't understand. */ | |
2014 | |
2015 t = base; | |
2016 STRIP_NOPS (t); | |
2017 if (TREE_CODE (t) == ADDR_EXPR | |
2018 && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST) | |
2019 { | |
2020 /* FIXME: Except that this causes problems elsewhere with dead | |
2021 code not being deleted, and we die in the rtl expanders | |
2022 because we failed to remove some ssa_name. In the meantime, | |
2023 just return zero. */ | |
2024 /* FIXME2: This condition should be signaled by | |
2025 fold_read_from_constant_string directly, rather than | |
2026 re-checking for it here. */ | |
2027 return integer_zero_node; | |
2028 } | |
2029 | |
2030 /* Try folding *(B+O) to B->X. Still an improvement. */ | |
2031 if (POINTER_TYPE_P (TREE_TYPE (base))) | |
2032 { | |
2033 t = maybe_fold_offset_to_reference (base, offset, | |
2034 TREE_TYPE (expr)); | |
2035 if (t) | |
2036 return t; | |
2037 } | |
2038 } | |
2039 | |
2040 /* Otherwise we had an offset that we could not simplify. */ | |
2041 return NULL_TREE; | |
2042 } | |
2043 | |
2044 | |
2045 /* A quaint feature extant in our address arithmetic is that there | |
2046 can be hidden type changes here. The type of the result need | |
2047 not be the same as the type of the input pointer. | |
2048 | |
2049 What we're after here is an expression of the form | |
2050 (T *)(&array + const) | |
2051 where array is OP0, const is OP1, RES_TYPE is T and | |
2052 the cast doesn't actually exist, but is implicit in the | |
2053 type of the POINTER_PLUS_EXPR. We'd like to turn this into | |
2054 &array[x] | |
2055 which may be able to propagate further. */ | |
2056 | |
2057 tree | |
2058 maybe_fold_stmt_addition (tree res_type, tree op0, tree op1) | |
2059 { | |
2060 tree ptd_type; | |
2061 tree t; | |
2062 | |
2063 /* It had better be a constant. */ | |
2064 if (TREE_CODE (op1) != INTEGER_CST) | |
2065 return NULL_TREE; | |
2066 /* The first operand should be an ADDR_EXPR. */ | |
2067 if (TREE_CODE (op0) != ADDR_EXPR) | |
2068 return NULL_TREE; | |
2069 op0 = TREE_OPERAND (op0, 0); | |
2070 | |
2071 /* If the first operand is an ARRAY_REF, expand it so that we can fold | |
2072 the offset into it. */ | |
2073 while (TREE_CODE (op0) == ARRAY_REF) | |
2074 { | |
2075 tree array_obj = TREE_OPERAND (op0, 0); | |
2076 tree array_idx = TREE_OPERAND (op0, 1); | |
2077 tree elt_type = TREE_TYPE (op0); | |
2078 tree elt_size = TYPE_SIZE_UNIT (elt_type); | |
2079 tree min_idx; | |
2080 | |
2081 if (TREE_CODE (array_idx) != INTEGER_CST) | |
2082 break; | |
2083 if (TREE_CODE (elt_size) != INTEGER_CST) | |
2084 break; | |
2085 | |
2086 /* Un-bias the index by the min index of the array type. */ | |
2087 min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj)); | |
2088 if (min_idx) | |
2089 { | |
2090 min_idx = TYPE_MIN_VALUE (min_idx); | |
2091 if (min_idx) | |
2092 { | |
2093 if (TREE_CODE (min_idx) != INTEGER_CST) | |
2094 break; | |
2095 | |
2096 array_idx = fold_convert (TREE_TYPE (min_idx), array_idx); | |
2097 if (!integer_zerop (min_idx)) | |
2098 array_idx = int_const_binop (MINUS_EXPR, array_idx, | |
2099 min_idx, 0); | |
2100 } | |
2101 } | |
2102 | |
2103 /* Convert the index to a byte offset. */ | |
2104 array_idx = fold_convert (sizetype, array_idx); | |
2105 array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0); | |
2106 | |
2107 /* Update the operands for the next round, or for folding. */ | |
2108 op1 = int_const_binop (PLUS_EXPR, | |
2109 array_idx, op1, 0); | |
2110 op0 = array_obj; | |
2111 } | |
2112 | |
2113 ptd_type = TREE_TYPE (res_type); | |
2114 /* If we want a pointer to void, reconstruct the reference from the | |
2115 array element type. A pointer to that can be trivially converted | |
2116 to void *. This happens as we fold (void *)(ptr p+ off). */ | |
2117 if (VOID_TYPE_P (ptd_type) | |
2118 && TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE) | |
2119 ptd_type = TREE_TYPE (TREE_TYPE (op0)); | |
2120 | |
2121 /* At which point we can try some of the same things as for indirects. */ | |
2122 t = maybe_fold_offset_to_array_ref (op0, op1, ptd_type, true); | |
2123 if (!t) | |
2124 t = maybe_fold_offset_to_component_ref (TREE_TYPE (op0), op0, op1, | |
47
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2125 ptd_type); |
0 | 2126 if (t) |
2127 t = build1 (ADDR_EXPR, res_type, t); | |
2128 | |
2129 return t; | |
2130 } | |
2131 | |
2132 /* For passing state through walk_tree into fold_stmt_r and its | |
2133 children. */ | |
2134 | |
2135 struct fold_stmt_r_data | |
2136 { | |
2137 gimple stmt; | |
2138 bool *changed_p; | |
2139 bool *inside_addr_expr_p; | |
2140 }; | |
2141 | |
2142 /* Subroutine of fold_stmt called via walk_tree. We perform several | |
2143 simplifications of EXPR_P, mostly having to do with pointer arithmetic. */ | |
2144 | |
2145 static tree | |
2146 fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data) | |
2147 { | |
2148 struct walk_stmt_info *wi = (struct walk_stmt_info *) data; | |
2149 struct fold_stmt_r_data *fold_stmt_r_data; | |
2150 bool *inside_addr_expr_p; | |
2151 bool *changed_p; | |
2152 tree expr = *expr_p, t; | |
2153 bool volatile_p = TREE_THIS_VOLATILE (expr); | |
2154 | |
2155 fold_stmt_r_data = (struct fold_stmt_r_data *) wi->info; | |
2156 inside_addr_expr_p = fold_stmt_r_data->inside_addr_expr_p; | |
2157 changed_p = fold_stmt_r_data->changed_p; | |
2158 | |
2159 /* ??? It'd be nice if walk_tree had a pre-order option. */ | |
2160 switch (TREE_CODE (expr)) | |
2161 { | |
2162 case INDIRECT_REF: | |
2163 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
2164 if (t) | |
2165 return t; | |
2166 *walk_subtrees = 0; | |
2167 | |
2168 t = maybe_fold_stmt_indirect (expr, TREE_OPERAND (expr, 0), | |
2169 integer_zero_node); | |
2170 /* Avoid folding *"abc" = 5 into 'a' = 5. */ | |
2171 if (wi->is_lhs && t && TREE_CODE (t) == INTEGER_CST) | |
2172 t = NULL_TREE; | |
2173 if (!t | |
2174 && TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR) | |
2175 /* If we had a good reason for propagating the address here, | |
2176 make sure we end up with valid gimple. See PR34989. */ | |
2177 t = TREE_OPERAND (TREE_OPERAND (expr, 0), 0); | |
2178 break; | |
2179 | |
2180 case NOP_EXPR: | |
2181 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
2182 if (t) | |
2183 return t; | |
2184 *walk_subtrees = 0; | |
2185 | |
2186 if (POINTER_TYPE_P (TREE_TYPE (expr)) | |
2187 && POINTER_TYPE_P (TREE_TYPE (TREE_TYPE (expr))) | |
2188 && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))) | |
2189 && (t = maybe_fold_offset_to_address (TREE_OPERAND (expr, 0), | |
2190 integer_zero_node, | |
2191 TREE_TYPE (TREE_TYPE (expr))))) | |
2192 return t; | |
2193 break; | |
2194 | |
2195 /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF. | |
2196 We'd only want to bother decomposing an existing ARRAY_REF if | |
2197 the base array is found to have another offset contained within. | |
2198 Otherwise we'd be wasting time. */ | |
2199 case ARRAY_REF: | |
2200 /* If we are not processing expressions found within an | |
2201 ADDR_EXPR, then we can fold constant array references. | |
2202 Don't fold on LHS either, to avoid folding "abc"[0] = 5 | |
2203 into 'a' = 5. */ | |
2204 if (!*inside_addr_expr_p && !wi->is_lhs) | |
2205 t = fold_read_from_constant_string (expr); | |
2206 else | |
2207 t = NULL; | |
2208 break; | |
2209 | |
2210 case ADDR_EXPR: | |
2211 *inside_addr_expr_p = true; | |
2212 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
2213 *inside_addr_expr_p = false; | |
2214 if (t) | |
2215 return t; | |
2216 *walk_subtrees = 0; | |
2217 | |
2218 /* Make sure the value is properly considered constant, and so gets | |
2219 propagated as expected. */ | |
2220 if (*changed_p) | |
2221 recompute_tree_invariant_for_addr_expr (expr); | |
2222 return NULL_TREE; | |
2223 | |
2224 case COMPONENT_REF: | |
2225 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
2226 if (t) | |
2227 return t; | |
2228 *walk_subtrees = 0; | |
2229 | |
2230 /* Make sure the FIELD_DECL is actually a field in the type on the lhs. | |
2231 We've already checked that the records are compatible, so we should | |
2232 come up with a set of compatible fields. */ | |
2233 { | |
2234 tree expr_record = TREE_TYPE (TREE_OPERAND (expr, 0)); | |
2235 tree expr_field = TREE_OPERAND (expr, 1); | |
2236 | |
2237 if (DECL_FIELD_CONTEXT (expr_field) != TYPE_MAIN_VARIANT (expr_record)) | |
2238 { | |
2239 expr_field = find_compatible_field (expr_record, expr_field); | |
2240 TREE_OPERAND (expr, 1) = expr_field; | |
2241 } | |
2242 } | |
2243 break; | |
2244 | |
2245 case TARGET_MEM_REF: | |
2246 t = maybe_fold_tmr (expr); | |
2247 break; | |
2248 | |
2249 case POINTER_PLUS_EXPR: | |
2250 t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
2251 if (t) | |
2252 return t; | |
2253 t = walk_tree (&TREE_OPERAND (expr, 1), fold_stmt_r, data, NULL); | |
2254 if (t) | |
2255 return t; | |
2256 *walk_subtrees = 0; | |
2257 | |
2258 t = maybe_fold_stmt_addition (TREE_TYPE (expr), | |
2259 TREE_OPERAND (expr, 0), | |
2260 TREE_OPERAND (expr, 1)); | |
2261 break; | |
2262 | |
2263 case COND_EXPR: | |
2264 if (COMPARISON_CLASS_P (TREE_OPERAND (expr, 0))) | |
2265 { | |
2266 tree op0 = TREE_OPERAND (expr, 0); | |
2267 tree tem; | |
2268 bool set; | |
2269 | |
2270 fold_defer_overflow_warnings (); | |
2271 tem = fold_binary (TREE_CODE (op0), TREE_TYPE (op0), | |
2272 TREE_OPERAND (op0, 0), | |
2273 TREE_OPERAND (op0, 1)); | |
2274 /* This is actually a conditional expression, not a GIMPLE | |
2275 conditional statement, however, the valid_gimple_rhs_p | |
2276 test still applies. */ | |
2277 set = tem && is_gimple_condexpr (tem) && valid_gimple_rhs_p (tem); | |
2278 fold_undefer_overflow_warnings (set, fold_stmt_r_data->stmt, 0); | |
2279 if (set) | |
2280 { | |
2281 COND_EXPR_COND (expr) = tem; | |
2282 t = expr; | |
2283 break; | |
2284 } | |
2285 } | |
2286 return NULL_TREE; | |
2287 | |
2288 default: | |
2289 return NULL_TREE; | |
2290 } | |
2291 | |
2292 if (t) | |
2293 { | |
2294 /* Preserve volatileness of the original expression. | |
2295 We can end up with a plain decl here which is shared | |
2296 and we shouldn't mess with its flags. */ | |
2297 if (!SSA_VAR_P (t)) | |
2298 TREE_THIS_VOLATILE (t) = volatile_p; | |
2299 *expr_p = t; | |
2300 *changed_p = true; | |
2301 } | |
2302 | |
2303 return NULL_TREE; | |
2304 } | |
2305 | |
2306 /* Return the string length, maximum string length or maximum value of | |
2307 ARG in LENGTH. | |
2308 If ARG is an SSA name variable, follow its use-def chains. If LENGTH | |
2309 is not NULL and, for TYPE == 0, its value is not equal to the length | |
2310 we determine or if we are unable to determine the length or value, | |
2311 return false. VISITED is a bitmap of visited variables. | |
2312 TYPE is 0 if string length should be returned, 1 for maximum string | |
2313 length and 2 for maximum value ARG can have. */ | |
2314 | |
2315 static bool | |
2316 get_maxval_strlen (tree arg, tree *length, bitmap visited, int type) | |
2317 { | |
2318 tree var, val; | |
2319 gimple def_stmt; | |
2320 | |
2321 if (TREE_CODE (arg) != SSA_NAME) | |
2322 { | |
2323 if (TREE_CODE (arg) == COND_EXPR) | |
2324 return get_maxval_strlen (COND_EXPR_THEN (arg), length, visited, type) | |
2325 && get_maxval_strlen (COND_EXPR_ELSE (arg), length, visited, type); | |
2326 /* We can end up with &(*iftmp_1)[0] here as well, so handle it. */ | |
2327 else if (TREE_CODE (arg) == ADDR_EXPR | |
2328 && TREE_CODE (TREE_OPERAND (arg, 0)) == ARRAY_REF | |
2329 && integer_zerop (TREE_OPERAND (TREE_OPERAND (arg, 0), 1))) | |
2330 { | |
2331 tree aop0 = TREE_OPERAND (TREE_OPERAND (arg, 0), 0); | |
2332 if (TREE_CODE (aop0) == INDIRECT_REF | |
2333 && TREE_CODE (TREE_OPERAND (aop0, 0)) == SSA_NAME) | |
2334 return get_maxval_strlen (TREE_OPERAND (aop0, 0), | |
2335 length, visited, type); | |
2336 } | |
2337 | |
2338 if (type == 2) | |
2339 { | |
2340 val = arg; | |
2341 if (TREE_CODE (val) != INTEGER_CST | |
2342 || tree_int_cst_sgn (val) < 0) | |
2343 return false; | |
2344 } | |
2345 else | |
2346 val = c_strlen (arg, 1); | |
2347 if (!val) | |
2348 return false; | |
2349 | |
2350 if (*length) | |
2351 { | |
2352 if (type > 0) | |
2353 { | |
2354 if (TREE_CODE (*length) != INTEGER_CST | |
2355 || TREE_CODE (val) != INTEGER_CST) | |
2356 return false; | |
2357 | |
2358 if (tree_int_cst_lt (*length, val)) | |
2359 *length = val; | |
2360 return true; | |
2361 } | |
2362 else if (simple_cst_equal (val, *length) != 1) | |
2363 return false; | |
2364 } | |
2365 | |
2366 *length = val; | |
2367 return true; | |
2368 } | |
2369 | |
2370 /* If we were already here, break the infinite cycle. */ | |
2371 if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg))) | |
2372 return true; | |
2373 bitmap_set_bit (visited, SSA_NAME_VERSION (arg)); | |
2374 | |
2375 var = arg; | |
2376 def_stmt = SSA_NAME_DEF_STMT (var); | |
2377 | |
2378 switch (gimple_code (def_stmt)) | |
2379 { | |
2380 case GIMPLE_ASSIGN: | |
2381 /* The RHS of the statement defining VAR must either have a | |
2382 constant length or come from another SSA_NAME with a constant | |
2383 length. */ | |
2384 if (gimple_assign_single_p (def_stmt) | |
2385 || gimple_assign_unary_nop_p (def_stmt)) | |
2386 { | |
2387 tree rhs = gimple_assign_rhs1 (def_stmt); | |
2388 return get_maxval_strlen (rhs, length, visited, type); | |
2389 } | |
2390 return false; | |
2391 | |
2392 case GIMPLE_PHI: | |
2393 { | |
2394 /* All the arguments of the PHI node must have the same constant | |
2395 length. */ | |
2396 unsigned i; | |
2397 | |
2398 for (i = 0; i < gimple_phi_num_args (def_stmt); i++) | |
2399 { | |
2400 tree arg = gimple_phi_arg (def_stmt, i)->def; | |
2401 | |
2402 /* If this PHI has itself as an argument, we cannot | |
2403 determine the string length of this argument. However, | |
2404 if we can find a constant string length for the other | |
2405 PHI args then we can still be sure that this is a | |
2406 constant string length. So be optimistic and just | |
2407 continue with the next argument. */ | |
2408 if (arg == gimple_phi_result (def_stmt)) | |
2409 continue; | |
2410 | |
2411 if (!get_maxval_strlen (arg, length, visited, type)) | |
2412 return false; | |
2413 } | |
2414 } | |
2415 return true; | |
2416 | |
2417 default: | |
2418 return false; | |
2419 } | |
2420 } | |
2421 | |
2422 | |
2423 /* Fold builtin call in statement STMT. Returns a simplified tree. | |
2424 We may return a non-constant expression, including another call | |
2425 to a different function and with different arguments, e.g., | |
2426 substituting memcpy for strcpy when the string length is known. | |
2427 Note that some builtins expand into inline code that may not | |
2428 be valid in GIMPLE. Callers must take care. */ | |
2429 | |
2430 static tree | |
2431 ccp_fold_builtin (gimple stmt) | |
2432 { | |
2433 tree result, val[3]; | |
2434 tree callee, a; | |
2435 int arg_idx, type; | |
2436 bitmap visited; | |
2437 bool ignore; | |
2438 int nargs; | |
2439 | |
2440 gcc_assert (is_gimple_call (stmt)); | |
2441 | |
2442 ignore = (gimple_call_lhs (stmt) == NULL); | |
2443 | |
2444 /* First try the generic builtin folder. If that succeeds, return the | |
2445 result directly. */ | |
2446 result = fold_call_stmt (stmt, ignore); | |
2447 if (result) | |
2448 { | |
2449 if (ignore) | |
2450 STRIP_NOPS (result); | |
2451 return result; | |
2452 } | |
2453 | |
2454 /* Ignore MD builtins. */ | |
2455 callee = gimple_call_fndecl (stmt); | |
2456 if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD) | |
2457 return NULL_TREE; | |
2458 | |
2459 /* If the builtin could not be folded, and it has no argument list, | |
2460 we're done. */ | |
2461 nargs = gimple_call_num_args (stmt); | |
2462 if (nargs == 0) | |
2463 return NULL_TREE; | |
2464 | |
2465 /* Limit the work only for builtins we know how to simplify. */ | |
2466 switch (DECL_FUNCTION_CODE (callee)) | |
2467 { | |
2468 case BUILT_IN_STRLEN: | |
2469 case BUILT_IN_FPUTS: | |
2470 case BUILT_IN_FPUTS_UNLOCKED: | |
2471 arg_idx = 0; | |
2472 type = 0; | |
2473 break; | |
2474 case BUILT_IN_STRCPY: | |
2475 case BUILT_IN_STRNCPY: | |
2476 arg_idx = 1; | |
2477 type = 0; | |
2478 break; | |
2479 case BUILT_IN_MEMCPY_CHK: | |
2480 case BUILT_IN_MEMPCPY_CHK: | |
2481 case BUILT_IN_MEMMOVE_CHK: | |
2482 case BUILT_IN_MEMSET_CHK: | |
2483 case BUILT_IN_STRNCPY_CHK: | |
2484 arg_idx = 2; | |
2485 type = 2; | |
2486 break; | |
2487 case BUILT_IN_STRCPY_CHK: | |
2488 case BUILT_IN_STPCPY_CHK: | |
2489 arg_idx = 1; | |
2490 type = 1; | |
2491 break; | |
2492 case BUILT_IN_SNPRINTF_CHK: | |
2493 case BUILT_IN_VSNPRINTF_CHK: | |
2494 arg_idx = 1; | |
2495 type = 2; | |
2496 break; | |
2497 default: | |
2498 return NULL_TREE; | |
2499 } | |
2500 | |
2501 if (arg_idx >= nargs) | |
2502 return NULL_TREE; | |
2503 | |
2504 /* Try to use the dataflow information gathered by the CCP process. */ | |
2505 visited = BITMAP_ALLOC (NULL); | |
2506 bitmap_clear (visited); | |
2507 | |
2508 memset (val, 0, sizeof (val)); | |
2509 a = gimple_call_arg (stmt, arg_idx); | |
2510 if (!get_maxval_strlen (a, &val[arg_idx], visited, type)) | |
2511 val[arg_idx] = NULL_TREE; | |
2512 | |
2513 BITMAP_FREE (visited); | |
2514 | |
2515 result = NULL_TREE; | |
2516 switch (DECL_FUNCTION_CODE (callee)) | |
2517 { | |
2518 case BUILT_IN_STRLEN: | |
2519 if (val[0] && nargs == 1) | |
2520 { | |
2521 tree new_val = | |
2522 fold_convert (TREE_TYPE (gimple_call_lhs (stmt)), val[0]); | |
2523 | |
2524 /* If the result is not a valid gimple value, or not a cast | |
2525 of a valid gimple value, then we can not use the result. */ | |
2526 if (is_gimple_val (new_val) | |
2527 || (is_gimple_cast (new_val) | |
2528 && is_gimple_val (TREE_OPERAND (new_val, 0)))) | |
2529 return new_val; | |
2530 } | |
2531 break; | |
2532 | |
2533 case BUILT_IN_STRCPY: | |
2534 if (val[1] && is_gimple_val (val[1]) && nargs == 2) | |
2535 result = fold_builtin_strcpy (callee, | |
2536 gimple_call_arg (stmt, 0), | |
2537 gimple_call_arg (stmt, 1), | |
2538 val[1]); | |
2539 break; | |
2540 | |
2541 case BUILT_IN_STRNCPY: | |
2542 if (val[1] && is_gimple_val (val[1]) && nargs == 3) | |
2543 result = fold_builtin_strncpy (callee, | |
2544 gimple_call_arg (stmt, 0), | |
2545 gimple_call_arg (stmt, 1), | |
2546 gimple_call_arg (stmt, 2), | |
2547 val[1]); | |
2548 break; | |
2549 | |
2550 case BUILT_IN_FPUTS: | |
2551 if (nargs == 2) | |
2552 result = fold_builtin_fputs (gimple_call_arg (stmt, 0), | |
2553 gimple_call_arg (stmt, 1), | |
2554 ignore, false, val[0]); | |
2555 break; | |
2556 | |
2557 case BUILT_IN_FPUTS_UNLOCKED: | |
2558 if (nargs == 2) | |
2559 result = fold_builtin_fputs (gimple_call_arg (stmt, 0), | |
2560 gimple_call_arg (stmt, 1), | |
2561 ignore, true, val[0]); | |
2562 break; | |
2563 | |
2564 case BUILT_IN_MEMCPY_CHK: | |
2565 case BUILT_IN_MEMPCPY_CHK: | |
2566 case BUILT_IN_MEMMOVE_CHK: | |
2567 case BUILT_IN_MEMSET_CHK: | |
2568 if (val[2] && is_gimple_val (val[2]) && nargs == 4) | |
2569 result = fold_builtin_memory_chk (callee, | |
2570 gimple_call_arg (stmt, 0), | |
2571 gimple_call_arg (stmt, 1), | |
2572 gimple_call_arg (stmt, 2), | |
2573 gimple_call_arg (stmt, 3), | |
2574 val[2], ignore, | |
2575 DECL_FUNCTION_CODE (callee)); | |
2576 break; | |
2577 | |
2578 case BUILT_IN_STRCPY_CHK: | |
2579 case BUILT_IN_STPCPY_CHK: | |
2580 if (val[1] && is_gimple_val (val[1]) && nargs == 3) | |
2581 result = fold_builtin_stxcpy_chk (callee, | |
2582 gimple_call_arg (stmt, 0), | |
2583 gimple_call_arg (stmt, 1), | |
2584 gimple_call_arg (stmt, 2), | |
2585 val[1], ignore, | |
2586 DECL_FUNCTION_CODE (callee)); | |
2587 break; | |
2588 | |
2589 case BUILT_IN_STRNCPY_CHK: | |
2590 if (val[2] && is_gimple_val (val[2]) && nargs == 4) | |
2591 result = fold_builtin_strncpy_chk (gimple_call_arg (stmt, 0), | |
2592 gimple_call_arg (stmt, 1), | |
2593 gimple_call_arg (stmt, 2), | |
2594 gimple_call_arg (stmt, 3), | |
2595 val[2]); | |
2596 break; | |
2597 | |
2598 case BUILT_IN_SNPRINTF_CHK: | |
2599 case BUILT_IN_VSNPRINTF_CHK: | |
2600 if (val[1] && is_gimple_val (val[1])) | |
2601 result = gimple_fold_builtin_snprintf_chk (stmt, val[1], | |
2602 DECL_FUNCTION_CODE (callee)); | |
2603 break; | |
2604 | |
2605 default: | |
2606 gcc_unreachable (); | |
2607 } | |
2608 | |
2609 if (result && ignore) | |
2610 result = fold_ignored_result (result); | |
2611 return result; | |
2612 } | |
2613 | |
2614 /* Attempt to fold an assignment statement pointed-to by SI. Returns a | |
2615 replacement rhs for the statement or NULL_TREE if no simplification | |
2616 could be made. It is assumed that the operands have been previously | |
2617 folded. */ | |
2618 | |
2619 static tree | |
2620 fold_gimple_assign (gimple_stmt_iterator *si) | |
2621 { | |
2622 gimple stmt = gsi_stmt (*si); | |
2623 enum tree_code subcode = gimple_assign_rhs_code (stmt); | |
2624 | |
2625 tree result = NULL; | |
2626 | |
2627 switch (get_gimple_rhs_class (subcode)) | |
2628 { | |
2629 case GIMPLE_SINGLE_RHS: | |
2630 { | |
2631 tree rhs = gimple_assign_rhs1 (stmt); | |
2632 | |
2633 /* Try to fold a conditional expression. */ | |
2634 if (TREE_CODE (rhs) == COND_EXPR) | |
2635 { | |
2636 tree temp = fold (COND_EXPR_COND (rhs)); | |
2637 if (temp != COND_EXPR_COND (rhs)) | |
2638 result = fold_build3 (COND_EXPR, TREE_TYPE (rhs), temp, | |
2639 COND_EXPR_THEN (rhs), COND_EXPR_ELSE (rhs)); | |
2640 } | |
2641 | |
2642 /* If we couldn't fold the RHS, hand over to the generic | |
2643 fold routines. */ | |
2644 if (result == NULL_TREE) | |
2645 result = fold (rhs); | |
2646 | |
2647 /* Strip away useless type conversions. Both the NON_LVALUE_EXPR | |
2648 that may have been added by fold, and "useless" type | |
2649 conversions that might now be apparent due to propagation. */ | |
2650 STRIP_USELESS_TYPE_CONVERSION (result); | |
2651 | |
2652 if (result != rhs && valid_gimple_rhs_p (result)) | |
2653 return result; | |
2654 else | |
2655 /* It is possible that fold_stmt_r simplified the RHS. | |
2656 Make sure that the subcode of this statement still | |
2657 reflects the principal operator of the rhs operand. */ | |
2658 return rhs; | |
2659 } | |
2660 break; | |
2661 | |
2662 case GIMPLE_UNARY_RHS: | |
2663 { | |
2664 tree rhs = gimple_assign_rhs1 (stmt); | |
2665 | |
2666 result = fold_unary (subcode, gimple_expr_type (stmt), rhs); | |
2667 if (result) | |
2668 { | |
2669 /* If the operation was a conversion do _not_ mark a | |
2670 resulting constant with TREE_OVERFLOW if the original | |
2671 constant was not. These conversions have implementation | |
2672 defined behavior and retaining the TREE_OVERFLOW flag | |
2673 here would confuse later passes such as VRP. */ | |
2674 if (CONVERT_EXPR_CODE_P (subcode) | |
2675 && TREE_CODE (result) == INTEGER_CST | |
2676 && TREE_CODE (rhs) == INTEGER_CST) | |
2677 TREE_OVERFLOW (result) = TREE_OVERFLOW (rhs); | |
2678 | |
2679 STRIP_USELESS_TYPE_CONVERSION (result); | |
2680 if (valid_gimple_rhs_p (result)) | |
2681 return result; | |
2682 } | |
2683 else if (CONVERT_EXPR_CODE_P (subcode) | |
2684 && POINTER_TYPE_P (gimple_expr_type (stmt)) | |
2685 && POINTER_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt)))) | |
2686 { | |
2687 tree type = gimple_expr_type (stmt); | |
2688 tree t = maybe_fold_offset_to_address (gimple_assign_rhs1 (stmt), | |
2689 integer_zero_node, type); | |
2690 if (t) | |
2691 return t; | |
2692 } | |
2693 } | |
2694 break; | |
2695 | |
2696 case GIMPLE_BINARY_RHS: | |
2697 /* Try to fold pointer addition. */ | |
2698 if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR) | |
2699 { | |
2700 tree type = TREE_TYPE (gimple_assign_rhs1 (stmt)); | |
2701 if (TREE_CODE (TREE_TYPE (type)) == ARRAY_TYPE) | |
2702 { | |
2703 type = build_pointer_type (TREE_TYPE (TREE_TYPE (type))); | |
2704 if (!useless_type_conversion_p | |
2705 (TREE_TYPE (gimple_assign_lhs (stmt)), type)) | |
2706 type = TREE_TYPE (gimple_assign_rhs1 (stmt)); | |
2707 } | |
2708 result = maybe_fold_stmt_addition (type, | |
2709 gimple_assign_rhs1 (stmt), | |
2710 gimple_assign_rhs2 (stmt)); | |
2711 } | |
2712 | |
2713 if (!result) | |
2714 result = fold_binary (subcode, | |
2715 TREE_TYPE (gimple_assign_lhs (stmt)), | |
2716 gimple_assign_rhs1 (stmt), | |
2717 gimple_assign_rhs2 (stmt)); | |
2718 | |
2719 if (result) | |
2720 { | |
2721 STRIP_USELESS_TYPE_CONVERSION (result); | |
2722 if (valid_gimple_rhs_p (result)) | |
2723 return result; | |
2724 | |
2725 /* Fold might have produced non-GIMPLE, so if we trust it blindly | |
2726 we lose canonicalization opportunities. Do not go again | |
2727 through fold here though, or the same non-GIMPLE will be | |
2728 produced. */ | |
2729 if (commutative_tree_code (subcode) | |
2730 && tree_swap_operands_p (gimple_assign_rhs1 (stmt), | |
2731 gimple_assign_rhs2 (stmt), false)) | |
2732 return build2 (subcode, TREE_TYPE (gimple_assign_lhs (stmt)), | |
2733 gimple_assign_rhs2 (stmt), | |
2734 gimple_assign_rhs1 (stmt)); | |
2735 } | |
2736 break; | |
2737 | |
2738 case GIMPLE_INVALID_RHS: | |
2739 gcc_unreachable (); | |
2740 } | |
2741 | |
2742 return NULL_TREE; | |
2743 } | |
2744 | |
2745 /* Attempt to fold a conditional statement. Return true if any changes were | |
2746 made. We only attempt to fold the condition expression, and do not perform | |
2747 any transformation that would require alteration of the cfg. It is | |
2748 assumed that the operands have been previously folded. */ | |
2749 | |
2750 static bool | |
2751 fold_gimple_cond (gimple stmt) | |
2752 { | |
2753 tree result = fold_binary (gimple_cond_code (stmt), | |
2754 boolean_type_node, | |
2755 gimple_cond_lhs (stmt), | |
2756 gimple_cond_rhs (stmt)); | |
2757 | |
2758 if (result) | |
2759 { | |
2760 STRIP_USELESS_TYPE_CONVERSION (result); | |
2761 if (is_gimple_condexpr (result) && valid_gimple_rhs_p (result)) | |
2762 { | |
2763 gimple_cond_set_condition_from_tree (stmt, result); | |
2764 return true; | |
2765 } | |
2766 } | |
2767 | |
2768 return false; | |
2769 } | |
2770 | |
2771 | |
2772 /* Attempt to fold a call statement referenced by the statement iterator GSI. | |
2773 The statement may be replaced by another statement, e.g., if the call | |
2774 simplifies to a constant value. Return true if any changes were made. | |
2775 It is assumed that the operands have been previously folded. */ | |
2776 | |
2777 static bool | |
2778 fold_gimple_call (gimple_stmt_iterator *gsi) | |
2779 { | |
2780 gimple stmt = gsi_stmt (*gsi); | |
2781 | |
2782 tree callee = gimple_call_fndecl (stmt); | |
2783 | |
2784 /* Check for builtins that CCP can handle using information not | |
2785 available in the generic fold routines. */ | |
2786 if (callee && DECL_BUILT_IN (callee)) | |
2787 { | |
2788 tree result = ccp_fold_builtin (stmt); | |
2789 | |
2790 if (result) | |
2791 return update_call_from_tree (gsi, result); | |
2792 } | |
2793 else | |
2794 { | |
2795 /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve | |
2796 here are when we've propagated the address of a decl into the | |
2797 object slot. */ | |
2798 /* ??? Should perhaps do this in fold proper. However, doing it | |
2799 there requires that we create a new CALL_EXPR, and that requires | |
2800 copying EH region info to the new node. Easier to just do it | |
2801 here where we can just smash the call operand. */ | |
2802 /* ??? Is there a good reason not to do this in fold_stmt_inplace? */ | |
2803 callee = gimple_call_fn (stmt); | |
2804 if (TREE_CODE (callee) == OBJ_TYPE_REF | |
2805 && lang_hooks.fold_obj_type_ref | |
2806 && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR | |
2807 && DECL_P (TREE_OPERAND | |
2808 (OBJ_TYPE_REF_OBJECT (callee), 0))) | |
2809 { | |
2810 tree t; | |
2811 | |
2812 /* ??? Caution: Broken ADDR_EXPR semantics means that | |
2813 looking at the type of the operand of the addr_expr | |
2814 can yield an array type. See silly exception in | |
2815 check_pointer_types_r. */ | |
2816 t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee))); | |
2817 t = lang_hooks.fold_obj_type_ref (callee, t); | |
2818 if (t) | |
2819 { | |
2820 gimple_call_set_fn (stmt, t); | |
2821 return true; | |
2822 } | |
2823 } | |
2824 } | |
2825 | |
2826 return false; | |
2827 } | |
2828 | |
2829 /* Fold the statement pointed to by GSI. In some cases, this function may | |
2830 replace the whole statement with a new one. Returns true iff folding | |
2831 makes any changes. */ | |
2832 | |
2833 bool | |
2834 fold_stmt (gimple_stmt_iterator *gsi) | |
2835 { | |
2836 tree res; | |
2837 struct fold_stmt_r_data fold_stmt_r_data; | |
2838 struct walk_stmt_info wi; | |
2839 | |
2840 bool changed = false; | |
2841 bool inside_addr_expr = false; | |
2842 | |
2843 gimple stmt = gsi_stmt (*gsi); | |
2844 | |
2845 fold_stmt_r_data.stmt = stmt; | |
2846 fold_stmt_r_data.changed_p = &changed; | |
2847 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr; | |
2848 | |
2849 memset (&wi, 0, sizeof (wi)); | |
2850 wi.info = &fold_stmt_r_data; | |
2851 | |
2852 /* Fold the individual operands. | |
2853 For example, fold instances of *&VAR into VAR, etc. */ | |
2854 res = walk_gimple_op (stmt, fold_stmt_r, &wi); | |
2855 gcc_assert (!res); | |
2856 | |
2857 /* Fold the main computation performed by the statement. */ | |
2858 switch (gimple_code (stmt)) | |
2859 { | |
2860 case GIMPLE_ASSIGN: | |
2861 { | |
2862 tree new_rhs = fold_gimple_assign (gsi); | |
2863 if (new_rhs != NULL_TREE) | |
2864 { | |
2865 gimple_assign_set_rhs_from_tree (gsi, new_rhs); | |
2866 changed = true; | |
2867 } | |
2868 stmt = gsi_stmt (*gsi); | |
2869 break; | |
2870 } | |
2871 case GIMPLE_COND: | |
2872 changed |= fold_gimple_cond (stmt); | |
2873 break; | |
2874 case GIMPLE_CALL: | |
2875 /* The entire statement may be replaced in this case. */ | |
2876 changed |= fold_gimple_call (gsi); | |
2877 break; | |
2878 | |
2879 default: | |
2880 return changed; | |
2881 break; | |
2882 } | |
2883 | |
2884 return changed; | |
2885 } | |
2886 | |
2887 /* Perform the minimal folding on statement STMT. Only operations like | |
2888 *&x created by constant propagation are handled. The statement cannot | |
2889 be replaced with a new one. Return true if the statement was | |
2890 changed, false otherwise. */ | |
2891 | |
2892 bool | |
2893 fold_stmt_inplace (gimple stmt) | |
2894 { | |
2895 tree res; | |
2896 struct fold_stmt_r_data fold_stmt_r_data; | |
2897 struct walk_stmt_info wi; | |
2898 gimple_stmt_iterator si; | |
2899 | |
2900 bool changed = false; | |
2901 bool inside_addr_expr = false; | |
2902 | |
2903 fold_stmt_r_data.stmt = stmt; | |
2904 fold_stmt_r_data.changed_p = &changed; | |
2905 fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr; | |
2906 | |
2907 memset (&wi, 0, sizeof (wi)); | |
2908 wi.info = &fold_stmt_r_data; | |
2909 | |
2910 /* Fold the individual operands. | |
2911 For example, fold instances of *&VAR into VAR, etc. | |
2912 | |
2913 It appears that, at one time, maybe_fold_stmt_indirect | |
2914 would cause the walk to return non-null in order to | |
2915 signal that the entire statement should be replaced with | |
2916 a call to _builtin_trap. This functionality is currently | |
2917 disabled, as noted in a FIXME, and cannot be supported here. */ | |
2918 res = walk_gimple_op (stmt, fold_stmt_r, &wi); | |
2919 gcc_assert (!res); | |
2920 | |
2921 /* Fold the main computation performed by the statement. */ | |
2922 switch (gimple_code (stmt)) | |
2923 { | |
2924 case GIMPLE_ASSIGN: | |
2925 { | |
2926 unsigned old_num_ops; | |
2927 tree new_rhs; | |
2928 old_num_ops = gimple_num_ops (stmt); | |
2929 si = gsi_for_stmt (stmt); | |
2930 new_rhs = fold_gimple_assign (&si); | |
2931 if (new_rhs != NULL_TREE | |
2932 && get_gimple_rhs_num_ops (TREE_CODE (new_rhs)) < old_num_ops) | |
2933 { | |
2934 gimple_assign_set_rhs_from_tree (&si, new_rhs); | |
2935 changed = true; | |
2936 } | |
2937 gcc_assert (gsi_stmt (si) == stmt); | |
2938 break; | |
2939 } | |
2940 case GIMPLE_COND: | |
2941 changed |= fold_gimple_cond (stmt); | |
2942 break; | |
2943 | |
2944 default: | |
2945 break; | |
2946 } | |
2947 | |
2948 return changed; | |
2949 } | |
2950 | |
2951 /* Try to optimize out __builtin_stack_restore. Optimize it out | |
2952 if there is another __builtin_stack_restore in the same basic | |
2953 block and no calls or ASM_EXPRs are in between, or if this block's | |
2954 only outgoing edge is to EXIT_BLOCK and there are no calls or | |
2955 ASM_EXPRs after this __builtin_stack_restore. */ | |
2956 | |
2957 static tree | |
2958 optimize_stack_restore (gimple_stmt_iterator i) | |
2959 { | |
2960 tree callee, rhs; | |
2961 gimple stmt, stack_save; | |
2962 gimple_stmt_iterator stack_save_gsi; | |
2963 | |
2964 basic_block bb = gsi_bb (i); | |
2965 gimple call = gsi_stmt (i); | |
2966 | |
2967 if (gimple_code (call) != GIMPLE_CALL | |
2968 || gimple_call_num_args (call) != 1 | |
2969 || TREE_CODE (gimple_call_arg (call, 0)) != SSA_NAME | |
2970 || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call, 0)))) | |
2971 return NULL_TREE; | |
2972 | |
2973 for (gsi_next (&i); !gsi_end_p (i); gsi_next (&i)) | |
2974 { | |
2975 stmt = gsi_stmt (i); | |
2976 if (gimple_code (stmt) == GIMPLE_ASM) | |
2977 return NULL_TREE; | |
2978 if (gimple_code (stmt) != GIMPLE_CALL) | |
2979 continue; | |
2980 | |
2981 callee = gimple_call_fndecl (stmt); | |
2982 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL) | |
2983 return NULL_TREE; | |
2984 | |
2985 if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE) | |
2986 break; | |
2987 } | |
2988 | |
2989 if (gsi_end_p (i) | |
2990 && (! single_succ_p (bb) | |
2991 || single_succ_edge (bb)->dest != EXIT_BLOCK_PTR)) | |
2992 return NULL_TREE; | |
2993 | |
2994 stack_save = SSA_NAME_DEF_STMT (gimple_call_arg (call, 0)); | |
2995 if (gimple_code (stack_save) != GIMPLE_CALL | |
2996 || gimple_call_lhs (stack_save) != gimple_call_arg (call, 0) | |
2997 || stmt_could_throw_p (stack_save) | |
2998 || !has_single_use (gimple_call_arg (call, 0))) | |
2999 return NULL_TREE; | |
3000 | |
3001 callee = gimple_call_fndecl (stack_save); | |
3002 if (!callee | |
3003 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL | |
3004 || DECL_FUNCTION_CODE (callee) != BUILT_IN_STACK_SAVE | |
3005 || gimple_call_num_args (stack_save) != 0) | |
3006 return NULL_TREE; | |
3007 | |
3008 stack_save_gsi = gsi_for_stmt (stack_save); | |
3009 push_stmt_changes (gsi_stmt_ptr (&stack_save_gsi)); | |
3010 rhs = build_int_cst (TREE_TYPE (gimple_call_arg (call, 0)), 0); | |
3011 if (!update_call_from_tree (&stack_save_gsi, rhs)) | |
3012 { | |
3013 discard_stmt_changes (gsi_stmt_ptr (&stack_save_gsi)); | |
3014 return NULL_TREE; | |
3015 } | |
3016 pop_stmt_changes (gsi_stmt_ptr (&stack_save_gsi)); | |
3017 | |
3018 /* No effect, so the statement will be deleted. */ | |
3019 return integer_zero_node; | |
3020 } | |
3021 | |
3022 /* If va_list type is a simple pointer and nothing special is needed, | |
3023 optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0), | |
3024 __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple | |
3025 pointer assignment. */ | |
3026 | |
3027 static tree | |
3028 optimize_stdarg_builtin (gimple call) | |
3029 { | |
3030 tree callee, lhs, rhs, cfun_va_list; | |
3031 bool va_list_simple_ptr; | |
3032 | |
3033 if (gimple_code (call) != GIMPLE_CALL) | |
3034 return NULL_TREE; | |
3035 | |
3036 callee = gimple_call_fndecl (call); | |
3037 | |
3038 cfun_va_list = targetm.fn_abi_va_list (callee); | |
3039 va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list) | |
3040 && (TREE_TYPE (cfun_va_list) == void_type_node | |
3041 || TREE_TYPE (cfun_va_list) == char_type_node); | |
3042 | |
3043 switch (DECL_FUNCTION_CODE (callee)) | |
3044 { | |
3045 case BUILT_IN_VA_START: | |
3046 if (!va_list_simple_ptr | |
3047 || targetm.expand_builtin_va_start != NULL | |
3048 || built_in_decls[BUILT_IN_NEXT_ARG] == NULL) | |
3049 return NULL_TREE; | |
3050 | |
3051 if (gimple_call_num_args (call) != 2) | |
3052 return NULL_TREE; | |
3053 | |
3054 lhs = gimple_call_arg (call, 0); | |
3055 if (!POINTER_TYPE_P (TREE_TYPE (lhs)) | |
3056 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs))) | |
3057 != TYPE_MAIN_VARIANT (cfun_va_list)) | |
3058 return NULL_TREE; | |
3059 | |
3060 lhs = build_fold_indirect_ref (lhs); | |
3061 rhs = build_call_expr (built_in_decls[BUILT_IN_NEXT_ARG], | |
3062 1, integer_zero_node); | |
3063 rhs = fold_convert (TREE_TYPE (lhs), rhs); | |
3064 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs); | |
3065 | |
3066 case BUILT_IN_VA_COPY: | |
3067 if (!va_list_simple_ptr) | |
3068 return NULL_TREE; | |
3069 | |
3070 if (gimple_call_num_args (call) != 2) | |
3071 return NULL_TREE; | |
3072 | |
3073 lhs = gimple_call_arg (call, 0); | |
3074 if (!POINTER_TYPE_P (TREE_TYPE (lhs)) | |
3075 || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs))) | |
3076 != TYPE_MAIN_VARIANT (cfun_va_list)) | |
3077 return NULL_TREE; | |
3078 | |
3079 lhs = build_fold_indirect_ref (lhs); | |
3080 rhs = gimple_call_arg (call, 1); | |
3081 if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs)) | |
3082 != TYPE_MAIN_VARIANT (cfun_va_list)) | |
3083 return NULL_TREE; | |
3084 | |
3085 rhs = fold_convert (TREE_TYPE (lhs), rhs); | |
3086 return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs); | |
3087 | |
3088 case BUILT_IN_VA_END: | |
3089 /* No effect, so the statement will be deleted. */ | |
3090 return integer_zero_node; | |
3091 | |
3092 default: | |
3093 gcc_unreachable (); | |
3094 } | |
3095 } | |
3096 | |
3097 /* Convert EXPR into a GIMPLE value suitable for substitution on the | |
3098 RHS of an assignment. Insert the necessary statements before | |
3099 iterator *SI_P. The statement at *SI_P, which must be a GIMPLE_CALL | |
3100 is replaced. If the call is expected to produces a result, then it | |
3101 is replaced by an assignment of the new RHS to the result variable. | |
3102 If the result is to be ignored, then the call is replaced by a | |
3103 GIMPLE_NOP. */ | |
3104 | |
3105 static void | |
3106 gimplify_and_update_call_from_tree (gimple_stmt_iterator *si_p, tree expr) | |
3107 { | |
3108 tree lhs; | |
3109 tree tmp = NULL_TREE; /* Silence warning. */ | |
3110 gimple stmt, new_stmt; | |
3111 gimple_stmt_iterator i; | |
3112 gimple_seq stmts = gimple_seq_alloc(); | |
3113 struct gimplify_ctx gctx; | |
3114 | |
3115 stmt = gsi_stmt (*si_p); | |
3116 | |
3117 gcc_assert (is_gimple_call (stmt)); | |
3118 | |
3119 lhs = gimple_call_lhs (stmt); | |
3120 | |
3121 push_gimplify_context (&gctx); | |
3122 | |
3123 if (lhs == NULL_TREE) | |
3124 gimplify_and_add (expr, &stmts); | |
3125 else | |
3126 tmp = get_initialized_tmp_var (expr, &stmts, NULL); | |
3127 | |
3128 pop_gimplify_context (NULL); | |
3129 | |
3130 if (gimple_has_location (stmt)) | |
3131 annotate_all_with_location (stmts, gimple_location (stmt)); | |
3132 | |
3133 /* The replacement can expose previously unreferenced variables. */ | |
3134 for (i = gsi_start (stmts); !gsi_end_p (i); gsi_next (&i)) | |
3135 { | |
3136 new_stmt = gsi_stmt (i); | |
3137 find_new_referenced_vars (new_stmt); | |
3138 gsi_insert_before (si_p, new_stmt, GSI_NEW_STMT); | |
3139 mark_symbols_for_renaming (new_stmt); | |
3140 gsi_next (si_p); | |
3141 } | |
3142 | |
3143 if (lhs == NULL_TREE) | |
3144 new_stmt = gimple_build_nop (); | |
3145 else | |
3146 { | |
3147 new_stmt = gimple_build_assign (lhs, tmp); | |
3148 copy_virtual_operands (new_stmt, stmt); | |
3149 move_ssa_defining_stmt_for_defs (new_stmt, stmt); | |
3150 } | |
3151 | |
3152 gimple_set_location (new_stmt, gimple_location (stmt)); | |
3153 gsi_replace (si_p, new_stmt, false); | |
3154 } | |
3155 | |
3156 /* A simple pass that attempts to fold all builtin functions. This pass | |
3157 is run after we've propagated as many constants as we can. */ | |
3158 | |
3159 static unsigned int | |
3160 execute_fold_all_builtins (void) | |
3161 { | |
3162 bool cfg_changed = false; | |
3163 basic_block bb; | |
3164 unsigned int todoflags = 0; | |
3165 | |
3166 FOR_EACH_BB (bb) | |
3167 { | |
3168 gimple_stmt_iterator i; | |
3169 for (i = gsi_start_bb (bb); !gsi_end_p (i); ) | |
3170 { | |
3171 gimple stmt, old_stmt; | |
3172 tree callee, result; | |
3173 enum built_in_function fcode; | |
3174 | |
3175 stmt = gsi_stmt (i); | |
3176 | |
3177 if (gimple_code (stmt) != GIMPLE_CALL) | |
3178 { | |
3179 gsi_next (&i); | |
3180 continue; | |
3181 } | |
3182 callee = gimple_call_fndecl (stmt); | |
3183 if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL) | |
3184 { | |
3185 gsi_next (&i); | |
3186 continue; | |
3187 } | |
3188 fcode = DECL_FUNCTION_CODE (callee); | |
3189 | |
3190 result = ccp_fold_builtin (stmt); | |
3191 | |
3192 if (result) | |
3193 gimple_remove_stmt_histograms (cfun, stmt); | |
3194 | |
3195 if (!result) | |
3196 switch (DECL_FUNCTION_CODE (callee)) | |
3197 { | |
3198 case BUILT_IN_CONSTANT_P: | |
3199 /* Resolve __builtin_constant_p. If it hasn't been | |
3200 folded to integer_one_node by now, it's fairly | |
3201 certain that the value simply isn't constant. */ | |
3202 result = integer_zero_node; | |
3203 break; | |
3204 | |
3205 case BUILT_IN_STACK_RESTORE: | |
3206 result = optimize_stack_restore (i); | |
3207 if (result) | |
3208 break; | |
3209 gsi_next (&i); | |
3210 continue; | |
3211 | |
3212 case BUILT_IN_VA_START: | |
3213 case BUILT_IN_VA_END: | |
3214 case BUILT_IN_VA_COPY: | |
3215 /* These shouldn't be folded before pass_stdarg. */ | |
3216 result = optimize_stdarg_builtin (stmt); | |
3217 if (result) | |
3218 break; | |
3219 /* FALLTHRU */ | |
3220 | |
3221 default: | |
3222 gsi_next (&i); | |
3223 continue; | |
3224 } | |
3225 | |
3226 if (dump_file && (dump_flags & TDF_DETAILS)) | |
3227 { | |
3228 fprintf (dump_file, "Simplified\n "); | |
3229 print_gimple_stmt (dump_file, stmt, 0, dump_flags); | |
3230 } | |
3231 | |
3232 old_stmt = stmt; | |
3233 push_stmt_changes (gsi_stmt_ptr (&i)); | |
3234 | |
3235 if (!update_call_from_tree (&i, result)) | |
3236 { | |
3237 gimplify_and_update_call_from_tree (&i, result); | |
3238 todoflags |= TODO_rebuild_alias; | |
3239 } | |
3240 | |
3241 stmt = gsi_stmt (i); | |
3242 pop_stmt_changes (gsi_stmt_ptr (&i)); | |
3243 | |
3244 if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt) | |
3245 && gimple_purge_dead_eh_edges (bb)) | |
3246 cfg_changed = true; | |
3247 | |
3248 if (dump_file && (dump_flags & TDF_DETAILS)) | |
3249 { | |
3250 fprintf (dump_file, "to\n "); | |
3251 print_gimple_stmt (dump_file, stmt, 0, dump_flags); | |
3252 fprintf (dump_file, "\n"); | |
3253 } | |
3254 | |
3255 /* Retry the same statement if it changed into another | |
3256 builtin, there might be new opportunities now. */ | |
3257 if (gimple_code (stmt) != GIMPLE_CALL) | |
3258 { | |
3259 gsi_next (&i); | |
3260 continue; | |
3261 } | |
3262 callee = gimple_call_fndecl (stmt); | |
3263 if (!callee | |
3264 || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL | |
3265 || DECL_FUNCTION_CODE (callee) == fcode) | |
3266 gsi_next (&i); | |
3267 } | |
3268 } | |
3269 | |
3270 /* Delete unreachable blocks. */ | |
3271 if (cfg_changed) | |
3272 todoflags |= TODO_cleanup_cfg; | |
3273 | |
3274 return todoflags; | |
3275 } | |
3276 | |
3277 | |
3278 struct gimple_opt_pass pass_fold_builtins = | |
3279 { | |
3280 { | |
3281 GIMPLE_PASS, | |
3282 "fab", /* name */ | |
3283 NULL, /* gate */ | |
3284 execute_fold_all_builtins, /* execute */ | |
3285 NULL, /* sub */ | |
3286 NULL, /* next */ | |
3287 0, /* static_pass_number */ | |
3288 0, /* tv_id */ | |
3289 PROP_cfg | PROP_ssa, /* properties_required */ | |
3290 0, /* properties_provided */ | |
3291 0, /* properties_destroyed */ | |
3292 0, /* todo_flags_start */ | |
3293 TODO_dump_func | |
3294 | TODO_verify_ssa | |
3295 | TODO_update_ssa /* todo_flags_finish */ | |
3296 } | |
3297 }; |