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1 | /* Conditional constant propagation pass for the GNU compiler. | |
2 | Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, | |
3 | 2010, 2011, 2012 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 | References: | |
103 | ||
104 | Constant propagation with conditional branches, | |
105 | Wegman and Zadeck, ACM TOPLAS 13(2):181-210. | |
106 | ||
107 | Building an Optimizing Compiler, | |
108 | Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9. | |
109 | ||
110 | Advanced Compiler Design and Implementation, | |
111 | Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */ | |
112 | ||
113 | #include "config.h" | |
114 | #include "system.h" | |
115 | #include "coretypes.h" | |
116 | #include "tm.h" | |
117 | #include "tree.h" | |
118 | #include "flags.h" | |
119 | #include "tm_p.h" | |
120 | #include "basic-block.h" | |
121 | #include "function.h" | |
122 | #include "gimple-pretty-print.h" | |
123 | #include "tree-flow.h" | |
124 | #include "tree-pass.h" | |
125 | #include "tree-ssa-propagate.h" | |
126 | #include "value-prof.h" | |
127 | #include "langhooks.h" | |
128 | #include "target.h" | |
129 | #include "diagnostic-core.h" | |
130 | #include "dbgcnt.h" | |
131 | #include "gimple-fold.h" | |
132 | #include "params.h" | |
133 | #include "hash-table.h" | |
134 | ||
135 | ||
136 | /* Possible lattice values. */ | |
137 | typedef enum | |
138 | { | |
139 | UNINITIALIZED, | |
140 | UNDEFINED, | |
141 | CONSTANT, | |
142 | VARYING | |
143 | } ccp_lattice_t; | |
144 | ||
145 | struct prop_value_d { | |
146 | /* Lattice value. */ | |
147 | ccp_lattice_t lattice_val; | |
148 | ||
149 | /* Propagated value. */ | |
150 | tree value; | |
151 | ||
152 | /* Mask that applies to the propagated value during CCP. For | |
153 | X with a CONSTANT lattice value X & ~mask == value & ~mask. */ | |
154 | double_int mask; | |
155 | }; | |
156 | ||
157 | typedef struct prop_value_d prop_value_t; | |
158 | ||
159 | /* Array of propagated constant values. After propagation, | |
160 | CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If | |
161 | the constant is held in an SSA name representing a memory store | |
162 | (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual | |
163 | memory reference used to store (i.e., the LHS of the assignment | |
164 | doing the store). */ | |
165 | static prop_value_t *const_val; | |
166 | ||
167 | static void canonicalize_float_value (prop_value_t *); | |
168 | static bool ccp_fold_stmt (gimple_stmt_iterator *); | |
169 | ||
170 | /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */ | |
171 | ||
172 | static void | |
173 | dump_lattice_value (FILE *outf, const char *prefix, prop_value_t val) | |
174 | { | |
175 | switch (val.lattice_val) | |
176 | { | |
177 | case UNINITIALIZED: | |
178 | fprintf (outf, "%sUNINITIALIZED", prefix); | |
179 | break; | |
180 | case UNDEFINED: | |
181 | fprintf (outf, "%sUNDEFINED", prefix); | |
182 | break; | |
183 | case VARYING: | |
184 | fprintf (outf, "%sVARYING", prefix); | |
185 | break; | |
186 | case CONSTANT: | |
187 | if (TREE_CODE (val.value) != INTEGER_CST | |
188 | || val.mask.is_zero ()) | |
189 | { | |
190 | fprintf (outf, "%sCONSTANT ", prefix); | |
191 | print_generic_expr (outf, val.value, dump_flags); | |
192 | } | |
193 | else | |
194 | { | |
195 | double_int cval = tree_to_double_int (val.value).and_not (val.mask); | |
196 | fprintf (outf, "%sCONSTANT " HOST_WIDE_INT_PRINT_DOUBLE_HEX, | |
197 | prefix, cval.high, cval.low); | |
198 | fprintf (outf, " (" HOST_WIDE_INT_PRINT_DOUBLE_HEX ")", | |
199 | val.mask.high, val.mask.low); | |
200 | } | |
201 | break; | |
202 | default: | |
203 | gcc_unreachable (); | |
204 | } | |
205 | } | |
206 | ||
207 | ||
208 | /* Print lattice value VAL to stderr. */ | |
209 | ||
210 | void debug_lattice_value (prop_value_t val); | |
211 | ||
212 | DEBUG_FUNCTION void | |
213 | debug_lattice_value (prop_value_t val) | |
214 | { | |
215 | dump_lattice_value (stderr, "", val); | |
216 | fprintf (stderr, "\n"); | |
217 | } | |
218 | ||
219 | ||
220 | /* Compute a default value for variable VAR and store it in the | |
221 | CONST_VAL array. The following rules are used to get default | |
222 | values: | |
223 | ||
224 | 1- Global and static variables that are declared constant are | |
225 | considered CONSTANT. | |
226 | ||
227 | 2- Any other value is considered UNDEFINED. This is useful when | |
228 | considering PHI nodes. PHI arguments that are undefined do not | |
229 | change the constant value of the PHI node, which allows for more | |
230 | constants to be propagated. | |
231 | ||
232 | 3- Variables defined by statements other than assignments and PHI | |
233 | nodes are considered VARYING. | |
234 | ||
235 | 4- Initial values of variables that are not GIMPLE registers are | |
236 | considered VARYING. */ | |
237 | ||
238 | static prop_value_t | |
239 | get_default_value (tree var) | |
240 | { | |
241 | prop_value_t val = { UNINITIALIZED, NULL_TREE, { 0, 0 } }; | |
242 | gimple stmt; | |
243 | ||
244 | stmt = SSA_NAME_DEF_STMT (var); | |
245 | ||
246 | if (gimple_nop_p (stmt)) | |
247 | { | |
248 | /* Variables defined by an empty statement are those used | |
249 | before being initialized. If VAR is a local variable, we | |
250 | can assume initially that it is UNDEFINED, otherwise we must | |
251 | consider it VARYING. */ | |
252 | if (!virtual_operand_p (var) | |
253 | && TREE_CODE (SSA_NAME_VAR (var)) == VAR_DECL) | |
254 | val.lattice_val = UNDEFINED; | |
255 | else | |
256 | { | |
257 | val.lattice_val = VARYING; | |
258 | val.mask = double_int_minus_one; | |
259 | } | |
260 | } | |
261 | else if (is_gimple_assign (stmt) | |
262 | /* Value-returning GIMPLE_CALL statements assign to | |
263 | a variable, and are treated similarly to GIMPLE_ASSIGN. */ | |
264 | || (is_gimple_call (stmt) | |
265 | && gimple_call_lhs (stmt) != NULL_TREE) | |
266 | || gimple_code (stmt) == GIMPLE_PHI) | |
267 | { | |
268 | tree cst; | |
269 | if (gimple_assign_single_p (stmt) | |
270 | && DECL_P (gimple_assign_rhs1 (stmt)) | |
271 | && (cst = get_symbol_constant_value (gimple_assign_rhs1 (stmt)))) | |
272 | { | |
273 | val.lattice_val = CONSTANT; | |
274 | val.value = cst; | |
275 | } | |
276 | else | |
277 | /* Any other variable defined by an assignment or a PHI node | |
278 | is considered UNDEFINED. */ | |
279 | val.lattice_val = UNDEFINED; | |
280 | } | |
281 | else | |
282 | { | |
283 | /* Otherwise, VAR will never take on a constant value. */ | |
284 | val.lattice_val = VARYING; | |
285 | val.mask = double_int_minus_one; | |
286 | } | |
287 | ||
288 | return val; | |
289 | } | |
290 | ||
291 | ||
292 | /* Get the constant value associated with variable VAR. */ | |
293 | ||
294 | static inline prop_value_t * | |
295 | get_value (tree var) | |
296 | { | |
297 | prop_value_t *val; | |
298 | ||
299 | if (const_val == NULL) | |
300 | return NULL; | |
301 | ||
302 | val = &const_val[SSA_NAME_VERSION (var)]; | |
303 | if (val->lattice_val == UNINITIALIZED) | |
304 | *val = get_default_value (var); | |
305 | ||
306 | canonicalize_float_value (val); | |
307 | ||
308 | return val; | |
309 | } | |
310 | ||
311 | /* Return the constant tree value associated with VAR. */ | |
312 | ||
313 | static inline tree | |
314 | get_constant_value (tree var) | |
315 | { | |
316 | prop_value_t *val; | |
317 | if (TREE_CODE (var) != SSA_NAME) | |
318 | { | |
319 | if (is_gimple_min_invariant (var)) | |
320 | return var; | |
321 | return NULL_TREE; | |
322 | } | |
323 | val = get_value (var); | |
324 | if (val | |
325 | && val->lattice_val == CONSTANT | |
326 | && (TREE_CODE (val->value) != INTEGER_CST | |
327 | || val->mask.is_zero ())) | |
328 | return val->value; | |
329 | return NULL_TREE; | |
330 | } | |
331 | ||
332 | /* Sets the value associated with VAR to VARYING. */ | |
333 | ||
334 | static inline void | |
335 | set_value_varying (tree var) | |
336 | { | |
337 | prop_value_t *val = &const_val[SSA_NAME_VERSION (var)]; | |
338 | ||
339 | val->lattice_val = VARYING; | |
340 | val->value = NULL_TREE; | |
341 | val->mask = double_int_minus_one; | |
342 | } | |
343 | ||
344 | /* For float types, modify the value of VAL to make ccp work correctly | |
345 | for non-standard values (-0, NaN): | |
346 | ||
347 | If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0. | |
348 | If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED. | |
349 | This is to fix the following problem (see PR 29921): Suppose we have | |
350 | ||
351 | x = 0.0 * y | |
352 | ||
353 | and we set value of y to NaN. This causes value of x to be set to NaN. | |
354 | When we later determine that y is in fact VARYING, fold uses the fact | |
355 | that HONOR_NANS is false, and we try to change the value of x to 0, | |
356 | causing an ICE. With HONOR_NANS being false, the real appearance of | |
357 | NaN would cause undefined behavior, though, so claiming that y (and x) | |
358 | are UNDEFINED initially is correct. */ | |
359 | ||
360 | static void | |
361 | canonicalize_float_value (prop_value_t *val) | |
362 | { | |
363 | enum machine_mode mode; | |
364 | tree type; | |
365 | REAL_VALUE_TYPE d; | |
366 | ||
367 | if (val->lattice_val != CONSTANT | |
368 | || TREE_CODE (val->value) != REAL_CST) | |
369 | return; | |
370 | ||
371 | d = TREE_REAL_CST (val->value); | |
372 | type = TREE_TYPE (val->value); | |
373 | mode = TYPE_MODE (type); | |
374 | ||
375 | if (!HONOR_SIGNED_ZEROS (mode) | |
376 | && REAL_VALUE_MINUS_ZERO (d)) | |
377 | { | |
378 | val->value = build_real (type, dconst0); | |
379 | return; | |
380 | } | |
381 | ||
382 | if (!HONOR_NANS (mode) | |
383 | && REAL_VALUE_ISNAN (d)) | |
384 | { | |
385 | val->lattice_val = UNDEFINED; | |
386 | val->value = NULL; | |
387 | return; | |
388 | } | |
389 | } | |
390 | ||
391 | /* Return whether the lattice transition is valid. */ | |
392 | ||
393 | static bool | |
394 | valid_lattice_transition (prop_value_t old_val, prop_value_t new_val) | |
395 | { | |
396 | /* Lattice transitions must always be monotonically increasing in | |
397 | value. */ | |
398 | if (old_val.lattice_val < new_val.lattice_val) | |
399 | return true; | |
400 | ||
401 | if (old_val.lattice_val != new_val.lattice_val) | |
402 | return false; | |
403 | ||
404 | if (!old_val.value && !new_val.value) | |
405 | return true; | |
406 | ||
407 | /* Now both lattice values are CONSTANT. */ | |
408 | ||
409 | /* Allow transitioning from PHI <&x, not executable> == &x | |
410 | to PHI <&x, &y> == common alignment. */ | |
411 | if (TREE_CODE (old_val.value) != INTEGER_CST | |
412 | && TREE_CODE (new_val.value) == INTEGER_CST) | |
413 | return true; | |
414 | ||
415 | /* Bit-lattices have to agree in the still valid bits. */ | |
416 | if (TREE_CODE (old_val.value) == INTEGER_CST | |
417 | && TREE_CODE (new_val.value) == INTEGER_CST) | |
418 | return tree_to_double_int (old_val.value).and_not (new_val.mask) | |
419 | == tree_to_double_int (new_val.value).and_not (new_val.mask); | |
420 | ||
421 | /* Otherwise constant values have to agree. */ | |
422 | return operand_equal_p (old_val.value, new_val.value, 0); | |
423 | } | |
424 | ||
425 | /* Set the value for variable VAR to NEW_VAL. Return true if the new | |
426 | value is different from VAR's previous value. */ | |
427 | ||
428 | static bool | |
429 | set_lattice_value (tree var, prop_value_t new_val) | |
430 | { | |
431 | /* We can deal with old UNINITIALIZED values just fine here. */ | |
432 | prop_value_t *old_val = &const_val[SSA_NAME_VERSION (var)]; | |
433 | ||
434 | canonicalize_float_value (&new_val); | |
435 | ||
436 | /* We have to be careful to not go up the bitwise lattice | |
437 | represented by the mask. | |
438 | ??? This doesn't seem to be the best place to enforce this. */ | |
439 | if (new_val.lattice_val == CONSTANT | |
440 | && old_val->lattice_val == CONSTANT | |
441 | && TREE_CODE (new_val.value) == INTEGER_CST | |
442 | && TREE_CODE (old_val->value) == INTEGER_CST) | |
443 | { | |
444 | double_int diff; | |
445 | diff = tree_to_double_int (new_val.value) | |
446 | ^ tree_to_double_int (old_val->value); | |
447 | new_val.mask = new_val.mask | old_val->mask | diff; | |
448 | } | |
449 | ||
450 | gcc_assert (valid_lattice_transition (*old_val, new_val)); | |
451 | ||
452 | /* If *OLD_VAL and NEW_VAL are the same, return false to inform the | |
453 | caller that this was a non-transition. */ | |
454 | if (old_val->lattice_val != new_val.lattice_val | |
455 | || (new_val.lattice_val == CONSTANT | |
456 | && TREE_CODE (new_val.value) == INTEGER_CST | |
457 | && (TREE_CODE (old_val->value) != INTEGER_CST | |
458 | || new_val.mask != old_val->mask))) | |
459 | { | |
460 | /* ??? We would like to delay creation of INTEGER_CSTs from | |
461 | partially constants here. */ | |
462 | ||
463 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
464 | { | |
465 | dump_lattice_value (dump_file, "Lattice value changed to ", new_val); | |
466 | fprintf (dump_file, ". Adding SSA edges to worklist.\n"); | |
467 | } | |
468 | ||
469 | *old_val = new_val; | |
470 | ||
471 | gcc_assert (new_val.lattice_val != UNINITIALIZED); | |
472 | return true; | |
473 | } | |
474 | ||
475 | return false; | |
476 | } | |
477 | ||
478 | static prop_value_t get_value_for_expr (tree, bool); | |
479 | static prop_value_t bit_value_binop (enum tree_code, tree, tree, tree); | |
480 | static void bit_value_binop_1 (enum tree_code, tree, double_int *, double_int *, | |
481 | tree, double_int, double_int, | |
482 | tree, double_int, double_int); | |
483 | ||
484 | /* Return a double_int that can be used for bitwise simplifications | |
485 | from VAL. */ | |
486 | ||
487 | static double_int | |
488 | value_to_double_int (prop_value_t val) | |
489 | { | |
490 | if (val.value | |
491 | && TREE_CODE (val.value) == INTEGER_CST) | |
492 | return tree_to_double_int (val.value); | |
493 | else | |
494 | return double_int_zero; | |
495 | } | |
496 | ||
497 | /* Return the value for the address expression EXPR based on alignment | |
498 | information. */ | |
499 | ||
500 | static prop_value_t | |
501 | get_value_from_alignment (tree expr) | |
502 | { | |
503 | tree type = TREE_TYPE (expr); | |
504 | prop_value_t val; | |
505 | unsigned HOST_WIDE_INT bitpos; | |
506 | unsigned int align; | |
507 | ||
508 | gcc_assert (TREE_CODE (expr) == ADDR_EXPR); | |
509 | ||
510 | get_pointer_alignment_1 (expr, &align, &bitpos); | |
511 | val.mask = (POINTER_TYPE_P (type) || TYPE_UNSIGNED (type) | |
512 | ? double_int::mask (TYPE_PRECISION (type)) | |
513 | : double_int_minus_one) | |
514 | .and_not (double_int::from_uhwi (align / BITS_PER_UNIT - 1)); | |
515 | val.lattice_val = val.mask.is_minus_one () ? VARYING : CONSTANT; | |
516 | if (val.lattice_val == CONSTANT) | |
517 | val.value | |
518 | = double_int_to_tree (type, | |
519 | double_int::from_uhwi (bitpos / BITS_PER_UNIT)); | |
520 | else | |
521 | val.value = NULL_TREE; | |
522 | ||
523 | return val; | |
524 | } | |
525 | ||
526 | /* Return the value for the tree operand EXPR. If FOR_BITS_P is true | |
527 | return constant bits extracted from alignment information for | |
528 | invariant addresses. */ | |
529 | ||
530 | static prop_value_t | |
531 | get_value_for_expr (tree expr, bool for_bits_p) | |
532 | { | |
533 | prop_value_t val; | |
534 | ||
535 | if (TREE_CODE (expr) == SSA_NAME) | |
536 | { | |
537 | val = *get_value (expr); | |
538 | if (for_bits_p | |
539 | && val.lattice_val == CONSTANT | |
540 | && TREE_CODE (val.value) == ADDR_EXPR) | |
541 | val = get_value_from_alignment (val.value); | |
542 | } | |
543 | else if (is_gimple_min_invariant (expr) | |
544 | && (!for_bits_p || TREE_CODE (expr) != ADDR_EXPR)) | |
545 | { | |
546 | val.lattice_val = CONSTANT; | |
547 | val.value = expr; | |
548 | val.mask = double_int_zero; | |
549 | canonicalize_float_value (&val); | |
550 | } | |
551 | else if (TREE_CODE (expr) == ADDR_EXPR) | |
552 | val = get_value_from_alignment (expr); | |
553 | else | |
554 | { | |
555 | val.lattice_val = VARYING; | |
556 | val.mask = double_int_minus_one; | |
557 | val.value = NULL_TREE; | |
558 | } | |
559 | return val; | |
560 | } | |
561 | ||
562 | /* Return the likely CCP lattice value for STMT. | |
563 | ||
564 | If STMT has no operands, then return CONSTANT. | |
565 | ||
566 | Else if undefinedness of operands of STMT cause its value to be | |
567 | undefined, then return UNDEFINED. | |
568 | ||
569 | Else if any operands of STMT are constants, then return CONSTANT. | |
570 | ||
571 | Else return VARYING. */ | |
572 | ||
573 | static ccp_lattice_t | |
574 | likely_value (gimple stmt) | |
575 | { | |
576 | bool has_constant_operand, has_undefined_operand, all_undefined_operands; | |
577 | tree use; | |
578 | ssa_op_iter iter; | |
579 | unsigned i; | |
580 | ||
581 | enum gimple_code code = gimple_code (stmt); | |
582 | ||
583 | /* This function appears to be called only for assignments, calls, | |
584 | conditionals, and switches, due to the logic in visit_stmt. */ | |
585 | gcc_assert (code == GIMPLE_ASSIGN | |
586 | || code == GIMPLE_CALL | |
587 | || code == GIMPLE_COND | |
588 | || code == GIMPLE_SWITCH); | |
589 | ||
590 | /* If the statement has volatile operands, it won't fold to a | |
591 | constant value. */ | |
592 | if (gimple_has_volatile_ops (stmt)) | |
593 | return VARYING; | |
594 | ||
595 | /* Arrive here for more complex cases. */ | |
596 | has_constant_operand = false; | |
597 | has_undefined_operand = false; | |
598 | all_undefined_operands = true; | |
599 | FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE) | |
600 | { | |
601 | prop_value_t *val = get_value (use); | |
602 | ||
603 | if (val->lattice_val == UNDEFINED) | |
604 | has_undefined_operand = true; | |
605 | else | |
606 | all_undefined_operands = false; | |
607 | ||
608 | if (val->lattice_val == CONSTANT) | |
609 | has_constant_operand = true; | |
610 | } | |
611 | ||
612 | /* There may be constants in regular rhs operands. For calls we | |
613 | have to ignore lhs, fndecl and static chain, otherwise only | |
614 | the lhs. */ | |
615 | for (i = (is_gimple_call (stmt) ? 2 : 0) + gimple_has_lhs (stmt); | |
616 | i < gimple_num_ops (stmt); ++i) | |
617 | { | |
618 | tree op = gimple_op (stmt, i); | |
619 | if (!op || TREE_CODE (op) == SSA_NAME) | |
620 | continue; | |
621 | if (is_gimple_min_invariant (op)) | |
622 | has_constant_operand = true; | |
623 | } | |
624 | ||
625 | if (has_constant_operand) | |
626 | all_undefined_operands = false; | |
627 | ||
628 | /* If the operation combines operands like COMPLEX_EXPR make sure to | |
629 | not mark the result UNDEFINED if only one part of the result is | |
630 | undefined. */ | |
631 | if (has_undefined_operand && all_undefined_operands) | |
632 | return UNDEFINED; | |
633 | else if (code == GIMPLE_ASSIGN && has_undefined_operand) | |
634 | { | |
635 | switch (gimple_assign_rhs_code (stmt)) | |
636 | { | |
637 | /* Unary operators are handled with all_undefined_operands. */ | |
638 | case PLUS_EXPR: | |
639 | case MINUS_EXPR: | |
640 | case POINTER_PLUS_EXPR: | |
641 | /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected. | |
642 | Not bitwise operators, one VARYING operand may specify the | |
643 | result completely. Not logical operators for the same reason. | |
644 | Not COMPLEX_EXPR as one VARYING operand makes the result partly | |
645 | not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because | |
646 | the undefined operand may be promoted. */ | |
647 | return UNDEFINED; | |
648 | ||
649 | case ADDR_EXPR: | |
650 | /* If any part of an address is UNDEFINED, like the index | |
651 | of an ARRAY_EXPR, then treat the result as UNDEFINED. */ | |
652 | return UNDEFINED; | |
653 | ||
654 | default: | |
655 | ; | |
656 | } | |
657 | } | |
658 | /* If there was an UNDEFINED operand but the result may be not UNDEFINED | |
659 | fall back to CONSTANT. During iteration UNDEFINED may still drop | |
660 | to CONSTANT. */ | |
661 | if (has_undefined_operand) | |
662 | return CONSTANT; | |
663 | ||
664 | /* We do not consider virtual operands here -- load from read-only | |
665 | memory may have only VARYING virtual operands, but still be | |
666 | constant. */ | |
667 | if (has_constant_operand | |
668 | || gimple_references_memory_p (stmt)) | |
669 | return CONSTANT; | |
670 | ||
671 | return VARYING; | |
672 | } | |
673 | ||
674 | /* Returns true if STMT cannot be constant. */ | |
675 | ||
676 | static bool | |
677 | surely_varying_stmt_p (gimple stmt) | |
678 | { | |
679 | /* If the statement has operands that we cannot handle, it cannot be | |
680 | constant. */ | |
681 | if (gimple_has_volatile_ops (stmt)) | |
682 | return true; | |
683 | ||
684 | /* If it is a call and does not return a value or is not a | |
685 | builtin and not an indirect call, it is varying. */ | |
686 | if (is_gimple_call (stmt)) | |
687 | { | |
688 | tree fndecl; | |
689 | if (!gimple_call_lhs (stmt) | |
690 | || ((fndecl = gimple_call_fndecl (stmt)) != NULL_TREE | |
691 | && !DECL_BUILT_IN (fndecl))) | |
692 | return true; | |
693 | } | |
694 | ||
695 | /* Any other store operation is not interesting. */ | |
696 | else if (gimple_vdef (stmt)) | |
697 | return true; | |
698 | ||
699 | /* Anything other than assignments and conditional jumps are not | |
700 | interesting for CCP. */ | |
701 | if (gimple_code (stmt) != GIMPLE_ASSIGN | |
702 | && gimple_code (stmt) != GIMPLE_COND | |
703 | && gimple_code (stmt) != GIMPLE_SWITCH | |
704 | && gimple_code (stmt) != GIMPLE_CALL) | |
705 | return true; | |
706 | ||
707 | return false; | |
708 | } | |
709 | ||
710 | /* Initialize local data structures for CCP. */ | |
711 | ||
712 | static void | |
713 | ccp_initialize (void) | |
714 | { | |
715 | basic_block bb; | |
716 | ||
717 | const_val = XCNEWVEC (prop_value_t, num_ssa_names); | |
718 | ||
719 | /* Initialize simulation flags for PHI nodes and statements. */ | |
720 | FOR_EACH_BB (bb) | |
721 | { | |
722 | gimple_stmt_iterator i; | |
723 | ||
724 | for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i)) | |
725 | { | |
726 | gimple stmt = gsi_stmt (i); | |
727 | bool is_varying; | |
728 | ||
729 | /* If the statement is a control insn, then we do not | |
730 | want to avoid simulating the statement once. Failure | |
731 | to do so means that those edges will never get added. */ | |
732 | if (stmt_ends_bb_p (stmt)) | |
733 | is_varying = false; | |
734 | else | |
735 | is_varying = surely_varying_stmt_p (stmt); | |
736 | ||
737 | if (is_varying) | |
738 | { | |
739 | tree def; | |
740 | ssa_op_iter iter; | |
741 | ||
742 | /* If the statement will not produce a constant, mark | |
743 | all its outputs VARYING. */ | |
744 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) | |
745 | set_value_varying (def); | |
746 | } | |
747 | prop_set_simulate_again (stmt, !is_varying); | |
748 | } | |
749 | } | |
750 | ||
751 | /* Now process PHI nodes. We never clear the simulate_again flag on | |
752 | phi nodes, since we do not know which edges are executable yet, | |
753 | except for phi nodes for virtual operands when we do not do store ccp. */ | |
754 | FOR_EACH_BB (bb) | |
755 | { | |
756 | gimple_stmt_iterator i; | |
757 | ||
758 | for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i)) | |
759 | { | |
760 | gimple phi = gsi_stmt (i); | |
761 | ||
762 | if (virtual_operand_p (gimple_phi_result (phi))) | |
763 | prop_set_simulate_again (phi, false); | |
764 | else | |
765 | prop_set_simulate_again (phi, true); | |
766 | } | |
767 | } | |
768 | } | |
769 | ||
770 | /* Debug count support. Reset the values of ssa names | |
771 | VARYING when the total number ssa names analyzed is | |
772 | beyond the debug count specified. */ | |
773 | ||
774 | static void | |
775 | do_dbg_cnt (void) | |
776 | { | |
777 | unsigned i; | |
778 | for (i = 0; i < num_ssa_names; i++) | |
779 | { | |
780 | if (!dbg_cnt (ccp)) | |
781 | { | |
782 | const_val[i].lattice_val = VARYING; | |
783 | const_val[i].mask = double_int_minus_one; | |
784 | const_val[i].value = NULL_TREE; | |
785 | } | |
786 | } | |
787 | } | |
788 | ||
789 | ||
790 | /* Do final substitution of propagated values, cleanup the flowgraph and | |
791 | free allocated storage. | |
792 | ||
793 | Return TRUE when something was optimized. */ | |
794 | ||
795 | static bool | |
796 | ccp_finalize (void) | |
797 | { | |
798 | bool something_changed; | |
799 | unsigned i; | |
800 | ||
801 | do_dbg_cnt (); | |
802 | ||
803 | /* Derive alignment and misalignment information from partially | |
804 | constant pointers in the lattice. */ | |
805 | for (i = 1; i < num_ssa_names; ++i) | |
806 | { | |
807 | tree name = ssa_name (i); | |
808 | prop_value_t *val; | |
809 | unsigned int tem, align; | |
810 | ||
811 | if (!name | |
812 | || !POINTER_TYPE_P (TREE_TYPE (name))) | |
813 | continue; | |
814 | ||
815 | val = get_value (name); | |
816 | if (val->lattice_val != CONSTANT | |
817 | || TREE_CODE (val->value) != INTEGER_CST) | |
818 | continue; | |
819 | ||
820 | /* Trailing constant bits specify the alignment, trailing value | |
821 | bits the misalignment. */ | |
822 | tem = val->mask.low; | |
823 | align = (tem & -tem); | |
824 | if (align > 1) | |
825 | set_ptr_info_alignment (get_ptr_info (name), align, | |
826 | TREE_INT_CST_LOW (val->value) & (align - 1)); | |
827 | } | |
828 | ||
829 | /* Perform substitutions based on the known constant values. */ | |
830 | something_changed = substitute_and_fold (get_constant_value, | |
831 | ccp_fold_stmt, true); | |
832 | ||
833 | free (const_val); | |
834 | const_val = NULL; | |
835 | return something_changed;; | |
836 | } | |
837 | ||
838 | ||
839 | /* Compute the meet operator between *VAL1 and *VAL2. Store the result | |
840 | in VAL1. | |
841 | ||
842 | any M UNDEFINED = any | |
843 | any M VARYING = VARYING | |
844 | Ci M Cj = Ci if (i == j) | |
845 | Ci M Cj = VARYING if (i != j) | |
846 | */ | |
847 | ||
848 | static void | |
849 | ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2) | |
850 | { | |
851 | if (val1->lattice_val == UNDEFINED) | |
852 | { | |
853 | /* UNDEFINED M any = any */ | |
854 | *val1 = *val2; | |
855 | } | |
856 | else if (val2->lattice_val == UNDEFINED) | |
857 | { | |
858 | /* any M UNDEFINED = any | |
859 | Nothing to do. VAL1 already contains the value we want. */ | |
860 | ; | |
861 | } | |
862 | else if (val1->lattice_val == VARYING | |
863 | || val2->lattice_val == VARYING) | |
864 | { | |
865 | /* any M VARYING = VARYING. */ | |
866 | val1->lattice_val = VARYING; | |
867 | val1->mask = double_int_minus_one; | |
868 | val1->value = NULL_TREE; | |
869 | } | |
870 | else if (val1->lattice_val == CONSTANT | |
871 | && val2->lattice_val == CONSTANT | |
872 | && TREE_CODE (val1->value) == INTEGER_CST | |
873 | && TREE_CODE (val2->value) == INTEGER_CST) | |
874 | { | |
875 | /* Ci M Cj = Ci if (i == j) | |
876 | Ci M Cj = VARYING if (i != j) | |
877 | ||
878 | For INTEGER_CSTs mask unequal bits. If no equal bits remain, | |
879 | drop to varying. */ | |
880 | val1->mask = val1->mask | val2->mask | |
881 | | (tree_to_double_int (val1->value) | |
882 | ^ tree_to_double_int (val2->value)); | |
883 | if (val1->mask.is_minus_one ()) | |
884 | { | |
885 | val1->lattice_val = VARYING; | |
886 | val1->value = NULL_TREE; | |
887 | } | |
888 | } | |
889 | else if (val1->lattice_val == CONSTANT | |
890 | && val2->lattice_val == CONSTANT | |
891 | && simple_cst_equal (val1->value, val2->value) == 1) | |
892 | { | |
893 | /* Ci M Cj = Ci if (i == j) | |
894 | Ci M Cj = VARYING if (i != j) | |
895 | ||
896 | VAL1 already contains the value we want for equivalent values. */ | |
897 | } | |
898 | else if (val1->lattice_val == CONSTANT | |
899 | && val2->lattice_val == CONSTANT | |
900 | && (TREE_CODE (val1->value) == ADDR_EXPR | |
901 | || TREE_CODE (val2->value) == ADDR_EXPR)) | |
902 | { | |
903 | /* When not equal addresses are involved try meeting for | |
904 | alignment. */ | |
905 | prop_value_t tem = *val2; | |
906 | if (TREE_CODE (val1->value) == ADDR_EXPR) | |
907 | *val1 = get_value_for_expr (val1->value, true); | |
908 | if (TREE_CODE (val2->value) == ADDR_EXPR) | |
909 | tem = get_value_for_expr (val2->value, true); | |
910 | ccp_lattice_meet (val1, &tem); | |
911 | } | |
912 | else | |
913 | { | |
914 | /* Any other combination is VARYING. */ | |
915 | val1->lattice_val = VARYING; | |
916 | val1->mask = double_int_minus_one; | |
917 | val1->value = NULL_TREE; | |
918 | } | |
919 | } | |
920 | ||
921 | ||
922 | /* Loop through the PHI_NODE's parameters for BLOCK and compare their | |
923 | lattice values to determine PHI_NODE's lattice value. The value of a | |
924 | PHI node is determined calling ccp_lattice_meet with all the arguments | |
925 | of the PHI node that are incoming via executable edges. */ | |
926 | ||
927 | static enum ssa_prop_result | |
928 | ccp_visit_phi_node (gimple phi) | |
929 | { | |
930 | unsigned i; | |
931 | prop_value_t *old_val, new_val; | |
932 | ||
933 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
934 | { | |
935 | fprintf (dump_file, "\nVisiting PHI node: "); | |
936 | print_gimple_stmt (dump_file, phi, 0, dump_flags); | |
937 | } | |
938 | ||
939 | old_val = get_value (gimple_phi_result (phi)); | |
940 | switch (old_val->lattice_val) | |
941 | { | |
942 | case VARYING: | |
943 | return SSA_PROP_VARYING; | |
944 | ||
945 | case CONSTANT: | |
946 | new_val = *old_val; | |
947 | break; | |
948 | ||
949 | case UNDEFINED: | |
950 | new_val.lattice_val = UNDEFINED; | |
951 | new_val.value = NULL_TREE; | |
952 | break; | |
953 | ||
954 | default: | |
955 | gcc_unreachable (); | |
956 | } | |
957 | ||
958 | for (i = 0; i < gimple_phi_num_args (phi); i++) | |
959 | { | |
960 | /* Compute the meet operator over all the PHI arguments flowing | |
961 | through executable edges. */ | |
962 | edge e = gimple_phi_arg_edge (phi, i); | |
963 | ||
964 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
965 | { | |
966 | fprintf (dump_file, | |
967 | "\n Argument #%d (%d -> %d %sexecutable)\n", | |
968 | i, e->src->index, e->dest->index, | |
969 | (e->flags & EDGE_EXECUTABLE) ? "" : "not "); | |
970 | } | |
971 | ||
972 | /* If the incoming edge is executable, Compute the meet operator for | |
973 | the existing value of the PHI node and the current PHI argument. */ | |
974 | if (e->flags & EDGE_EXECUTABLE) | |
975 | { | |
976 | tree arg = gimple_phi_arg (phi, i)->def; | |
977 | prop_value_t arg_val = get_value_for_expr (arg, false); | |
978 | ||
979 | ccp_lattice_meet (&new_val, &arg_val); | |
980 | ||
981 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
982 | { | |
983 | fprintf (dump_file, "\t"); | |
984 | print_generic_expr (dump_file, arg, dump_flags); | |
985 | dump_lattice_value (dump_file, "\tValue: ", arg_val); | |
986 | fprintf (dump_file, "\n"); | |
987 | } | |
988 | ||
989 | if (new_val.lattice_val == VARYING) | |
990 | break; | |
991 | } | |
992 | } | |
993 | ||
994 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
995 | { | |
996 | dump_lattice_value (dump_file, "\n PHI node value: ", new_val); | |
997 | fprintf (dump_file, "\n\n"); | |
998 | } | |
999 | ||
1000 | /* Make the transition to the new value. */ | |
1001 | if (set_lattice_value (gimple_phi_result (phi), new_val)) | |
1002 | { | |
1003 | if (new_val.lattice_val == VARYING) | |
1004 | return SSA_PROP_VARYING; | |
1005 | else | |
1006 | return SSA_PROP_INTERESTING; | |
1007 | } | |
1008 | else | |
1009 | return SSA_PROP_NOT_INTERESTING; | |
1010 | } | |
1011 | ||
1012 | /* Return the constant value for OP or OP otherwise. */ | |
1013 | ||
1014 | static tree | |
1015 | valueize_op (tree op) | |
1016 | { | |
1017 | if (TREE_CODE (op) == SSA_NAME) | |
1018 | { | |
1019 | tree tem = get_constant_value (op); | |
1020 | if (tem) | |
1021 | return tem; | |
1022 | } | |
1023 | return op; | |
1024 | } | |
1025 | ||
1026 | /* CCP specific front-end to the non-destructive constant folding | |
1027 | routines. | |
1028 | ||
1029 | Attempt to simplify the RHS of STMT knowing that one or more | |
1030 | operands are constants. | |
1031 | ||
1032 | If simplification is possible, return the simplified RHS, | |
1033 | otherwise return the original RHS or NULL_TREE. */ | |
1034 | ||
1035 | static tree | |
1036 | ccp_fold (gimple stmt) | |
1037 | { | |
1038 | location_t loc = gimple_location (stmt); | |
1039 | switch (gimple_code (stmt)) | |
1040 | { | |
1041 | case GIMPLE_COND: | |
1042 | { | |
1043 | /* Handle comparison operators that can appear in GIMPLE form. */ | |
1044 | tree op0 = valueize_op (gimple_cond_lhs (stmt)); | |
1045 | tree op1 = valueize_op (gimple_cond_rhs (stmt)); | |
1046 | enum tree_code code = gimple_cond_code (stmt); | |
1047 | return fold_binary_loc (loc, code, boolean_type_node, op0, op1); | |
1048 | } | |
1049 | ||
1050 | case GIMPLE_SWITCH: | |
1051 | { | |
1052 | /* Return the constant switch index. */ | |
1053 | return valueize_op (gimple_switch_index (stmt)); | |
1054 | } | |
1055 | ||
1056 | case GIMPLE_ASSIGN: | |
1057 | case GIMPLE_CALL: | |
1058 | return gimple_fold_stmt_to_constant_1 (stmt, valueize_op); | |
1059 | ||
1060 | default: | |
1061 | gcc_unreachable (); | |
1062 | } | |
1063 | } | |
1064 | ||
1065 | /* Apply the operation CODE in type TYPE to the value, mask pair | |
1066 | RVAL and RMASK representing a value of type RTYPE and set | |
1067 | the value, mask pair *VAL and *MASK to the result. */ | |
1068 | ||
1069 | static void | |
1070 | bit_value_unop_1 (enum tree_code code, tree type, | |
1071 | double_int *val, double_int *mask, | |
1072 | tree rtype, double_int rval, double_int rmask) | |
1073 | { | |
1074 | switch (code) | |
1075 | { | |
1076 | case BIT_NOT_EXPR: | |
1077 | *mask = rmask; | |
1078 | *val = ~rval; | |
1079 | break; | |
1080 | ||
1081 | case NEGATE_EXPR: | |
1082 | { | |
1083 | double_int temv, temm; | |
1084 | /* Return ~rval + 1. */ | |
1085 | bit_value_unop_1 (BIT_NOT_EXPR, type, &temv, &temm, type, rval, rmask); | |
1086 | bit_value_binop_1 (PLUS_EXPR, type, val, mask, | |
1087 | type, temv, temm, | |
1088 | type, double_int_one, double_int_zero); | |
1089 | break; | |
1090 | } | |
1091 | ||
1092 | CASE_CONVERT: | |
1093 | { | |
1094 | bool uns; | |
1095 | ||
1096 | /* First extend mask and value according to the original type. */ | |
1097 | uns = TYPE_UNSIGNED (rtype); | |
1098 | *mask = rmask.ext (TYPE_PRECISION (rtype), uns); | |
1099 | *val = rval.ext (TYPE_PRECISION (rtype), uns); | |
1100 | ||
1101 | /* Then extend mask and value according to the target type. */ | |
1102 | uns = TYPE_UNSIGNED (type); | |
1103 | *mask = (*mask).ext (TYPE_PRECISION (type), uns); | |
1104 | *val = (*val).ext (TYPE_PRECISION (type), uns); | |
1105 | break; | |
1106 | } | |
1107 | ||
1108 | default: | |
1109 | *mask = double_int_minus_one; | |
1110 | break; | |
1111 | } | |
1112 | } | |
1113 | ||
1114 | /* Apply the operation CODE in type TYPE to the value, mask pairs | |
1115 | R1VAL, R1MASK and R2VAL, R2MASK representing a values of type R1TYPE | |
1116 | and R2TYPE and set the value, mask pair *VAL and *MASK to the result. */ | |
1117 | ||
1118 | static void | |
1119 | bit_value_binop_1 (enum tree_code code, tree type, | |
1120 | double_int *val, double_int *mask, | |
1121 | tree r1type, double_int r1val, double_int r1mask, | |
1122 | tree r2type, double_int r2val, double_int r2mask) | |
1123 | { | |
1124 | bool uns = TYPE_UNSIGNED (type); | |
1125 | /* Assume we'll get a constant result. Use an initial varying value, | |
1126 | we fall back to varying in the end if necessary. */ | |
1127 | *mask = double_int_minus_one; | |
1128 | switch (code) | |
1129 | { | |
1130 | case BIT_AND_EXPR: | |
1131 | /* The mask is constant where there is a known not | |
1132 | set bit, (m1 | m2) & ((v1 | m1) & (v2 | m2)) */ | |
1133 | *mask = (r1mask | r2mask) & (r1val | r1mask) & (r2val | r2mask); | |
1134 | *val = r1val & r2val; | |
1135 | break; | |
1136 | ||
1137 | case BIT_IOR_EXPR: | |
1138 | /* The mask is constant where there is a known | |
1139 | set bit, (m1 | m2) & ~((v1 & ~m1) | (v2 & ~m2)). */ | |
1140 | *mask = (r1mask | r2mask) | |
1141 | .and_not (r1val.and_not (r1mask) | r2val.and_not (r2mask)); | |
1142 | *val = r1val | r2val; | |
1143 | break; | |
1144 | ||
1145 | case BIT_XOR_EXPR: | |
1146 | /* m1 | m2 */ | |
1147 | *mask = r1mask | r2mask; | |
1148 | *val = r1val ^ r2val; | |
1149 | break; | |
1150 | ||
1151 | case LROTATE_EXPR: | |
1152 | case RROTATE_EXPR: | |
1153 | if (r2mask.is_zero ()) | |
1154 | { | |
1155 | HOST_WIDE_INT shift = r2val.low; | |
1156 | if (code == RROTATE_EXPR) | |
1157 | shift = -shift; | |
1158 | *mask = r1mask.lrotate (shift, TYPE_PRECISION (type)); | |
1159 | *val = r1val.lrotate (shift, TYPE_PRECISION (type)); | |
1160 | } | |
1161 | break; | |
1162 | ||
1163 | case LSHIFT_EXPR: | |
1164 | case RSHIFT_EXPR: | |
1165 | /* ??? We can handle partially known shift counts if we know | |
1166 | its sign. That way we can tell that (x << (y | 8)) & 255 | |
1167 | is zero. */ | |
1168 | if (r2mask.is_zero ()) | |
1169 | { | |
1170 | HOST_WIDE_INT shift = r2val.low; | |
1171 | if (code == RSHIFT_EXPR) | |
1172 | shift = -shift; | |
1173 | /* We need to know if we are doing a left or a right shift | |
1174 | to properly shift in zeros for left shift and unsigned | |
1175 | right shifts and the sign bit for signed right shifts. | |
1176 | For signed right shifts we shift in varying in case | |
1177 | the sign bit was varying. */ | |
1178 | if (shift > 0) | |
1179 | { | |
1180 | *mask = r1mask.llshift (shift, TYPE_PRECISION (type)); | |
1181 | *val = r1val.llshift (shift, TYPE_PRECISION (type)); | |
1182 | } | |
1183 | else if (shift < 0) | |
1184 | { | |
1185 | shift = -shift; | |
1186 | *mask = r1mask.rshift (shift, TYPE_PRECISION (type), !uns); | |
1187 | *val = r1val.rshift (shift, TYPE_PRECISION (type), !uns); | |
1188 | } | |
1189 | else | |
1190 | { | |
1191 | *mask = r1mask; | |
1192 | *val = r1val; | |
1193 | } | |
1194 | } | |
1195 | break; | |
1196 | ||
1197 | case PLUS_EXPR: | |
1198 | case POINTER_PLUS_EXPR: | |
1199 | { | |
1200 | double_int lo, hi; | |
1201 | /* Do the addition with unknown bits set to zero, to give carry-ins of | |
1202 | zero wherever possible. */ | |
1203 | lo = r1val.and_not (r1mask) + r2val.and_not (r2mask); | |
1204 | lo = lo.ext (TYPE_PRECISION (type), uns); | |
1205 | /* Do the addition with unknown bits set to one, to give carry-ins of | |
1206 | one wherever possible. */ | |
1207 | hi = (r1val | r1mask) + (r2val | r2mask); | |
1208 | hi = hi.ext (TYPE_PRECISION (type), uns); | |
1209 | /* Each bit in the result is known if (a) the corresponding bits in | |
1210 | both inputs are known, and (b) the carry-in to that bit position | |
1211 | is known. We can check condition (b) by seeing if we got the same | |
1212 | result with minimised carries as with maximised carries. */ | |
1213 | *mask = r1mask | r2mask | (lo ^ hi); | |
1214 | *mask = (*mask).ext (TYPE_PRECISION (type), uns); | |
1215 | /* It shouldn't matter whether we choose lo or hi here. */ | |
1216 | *val = lo; | |
1217 | break; | |
1218 | } | |
1219 | ||
1220 | case MINUS_EXPR: | |
1221 | { | |
1222 | double_int temv, temm; | |
1223 | bit_value_unop_1 (NEGATE_EXPR, r2type, &temv, &temm, | |
1224 | r2type, r2val, r2mask); | |
1225 | bit_value_binop_1 (PLUS_EXPR, type, val, mask, | |
1226 | r1type, r1val, r1mask, | |
1227 | r2type, temv, temm); | |
1228 | break; | |
1229 | } | |
1230 | ||
1231 | case MULT_EXPR: | |
1232 | { | |
1233 | /* Just track trailing zeros in both operands and transfer | |
1234 | them to the other. */ | |
1235 | int r1tz = (r1val | r1mask).trailing_zeros (); | |
1236 | int r2tz = (r2val | r2mask).trailing_zeros (); | |
1237 | if (r1tz + r2tz >= HOST_BITS_PER_DOUBLE_INT) | |
1238 | { | |
1239 | *mask = double_int_zero; | |
1240 | *val = double_int_zero; | |
1241 | } | |
1242 | else if (r1tz + r2tz > 0) | |
1243 | { | |
1244 | *mask = ~double_int::mask (r1tz + r2tz); | |
1245 | *mask = (*mask).ext (TYPE_PRECISION (type), uns); | |
1246 | *val = double_int_zero; | |
1247 | } | |
1248 | break; | |
1249 | } | |
1250 | ||
1251 | case EQ_EXPR: | |
1252 | case NE_EXPR: | |
1253 | { | |
1254 | double_int m = r1mask | r2mask; | |
1255 | if (r1val.and_not (m) != r2val.and_not (m)) | |
1256 | { | |
1257 | *mask = double_int_zero; | |
1258 | *val = ((code == EQ_EXPR) ? double_int_zero : double_int_one); | |
1259 | } | |
1260 | else | |
1261 | { | |
1262 | /* We know the result of a comparison is always one or zero. */ | |
1263 | *mask = double_int_one; | |
1264 | *val = double_int_zero; | |
1265 | } | |
1266 | break; | |
1267 | } | |
1268 | ||
1269 | case GE_EXPR: | |
1270 | case GT_EXPR: | |
1271 | { | |
1272 | double_int tem = r1val; | |
1273 | r1val = r2val; | |
1274 | r2val = tem; | |
1275 | tem = r1mask; | |
1276 | r1mask = r2mask; | |
1277 | r2mask = tem; | |
1278 | code = swap_tree_comparison (code); | |
1279 | } | |
1280 | /* Fallthru. */ | |
1281 | case LT_EXPR: | |
1282 | case LE_EXPR: | |
1283 | { | |
1284 | int minmax, maxmin; | |
1285 | /* If the most significant bits are not known we know nothing. */ | |
1286 | if (r1mask.is_negative () || r2mask.is_negative ()) | |
1287 | break; | |
1288 | ||
1289 | /* For comparisons the signedness is in the comparison operands. */ | |
1290 | uns = TYPE_UNSIGNED (r1type); | |
1291 | ||
1292 | /* If we know the most significant bits we know the values | |
1293 | value ranges by means of treating varying bits as zero | |
1294 | or one. Do a cross comparison of the max/min pairs. */ | |
1295 | maxmin = (r1val | r1mask).cmp (r2val.and_not (r2mask), uns); | |
1296 | minmax = r1val.and_not (r1mask).cmp (r2val | r2mask, uns); | |
1297 | if (maxmin < 0) /* r1 is less than r2. */ | |
1298 | { | |
1299 | *mask = double_int_zero; | |
1300 | *val = double_int_one; | |
1301 | } | |
1302 | else if (minmax > 0) /* r1 is not less or equal to r2. */ | |
1303 | { | |
1304 | *mask = double_int_zero; | |
1305 | *val = double_int_zero; | |
1306 | } | |
1307 | else if (maxmin == minmax) /* r1 and r2 are equal. */ | |
1308 | { | |
1309 | /* This probably should never happen as we'd have | |
1310 | folded the thing during fully constant value folding. */ | |
1311 | *mask = double_int_zero; | |
1312 | *val = (code == LE_EXPR ? double_int_one : double_int_zero); | |
1313 | } | |
1314 | else | |
1315 | { | |
1316 | /* We know the result of a comparison is always one or zero. */ | |
1317 | *mask = double_int_one; | |
1318 | *val = double_int_zero; | |
1319 | } | |
1320 | break; | |
1321 | } | |
1322 | ||
1323 | default:; | |
1324 | } | |
1325 | } | |
1326 | ||
1327 | /* Return the propagation value when applying the operation CODE to | |
1328 | the value RHS yielding type TYPE. */ | |
1329 | ||
1330 | static prop_value_t | |
1331 | bit_value_unop (enum tree_code code, tree type, tree rhs) | |
1332 | { | |
1333 | prop_value_t rval = get_value_for_expr (rhs, true); | |
1334 | double_int value, mask; | |
1335 | prop_value_t val; | |
1336 | ||
1337 | if (rval.lattice_val == UNDEFINED) | |
1338 | return rval; | |
1339 | ||
1340 | gcc_assert ((rval.lattice_val == CONSTANT | |
1341 | && TREE_CODE (rval.value) == INTEGER_CST) | |
1342 | || rval.mask.is_minus_one ()); | |
1343 | bit_value_unop_1 (code, type, &value, &mask, | |
1344 | TREE_TYPE (rhs), value_to_double_int (rval), rval.mask); | |
1345 | if (!mask.is_minus_one ()) | |
1346 | { | |
1347 | val.lattice_val = CONSTANT; | |
1348 | val.mask = mask; | |
1349 | /* ??? Delay building trees here. */ | |
1350 | val.value = double_int_to_tree (type, value); | |
1351 | } | |
1352 | else | |
1353 | { | |
1354 | val.lattice_val = VARYING; | |
1355 | val.value = NULL_TREE; | |
1356 | val.mask = double_int_minus_one; | |
1357 | } | |
1358 | return val; | |
1359 | } | |
1360 | ||
1361 | /* Return the propagation value when applying the operation CODE to | |
1362 | the values RHS1 and RHS2 yielding type TYPE. */ | |
1363 | ||
1364 | static prop_value_t | |
1365 | bit_value_binop (enum tree_code code, tree type, tree rhs1, tree rhs2) | |
1366 | { | |
1367 | prop_value_t r1val = get_value_for_expr (rhs1, true); | |
1368 | prop_value_t r2val = get_value_for_expr (rhs2, true); | |
1369 | double_int value, mask; | |
1370 | prop_value_t val; | |
1371 | ||
1372 | if (r1val.lattice_val == UNDEFINED | |
1373 | || r2val.lattice_val == UNDEFINED) | |
1374 | { | |
1375 | val.lattice_val = VARYING; | |
1376 | val.value = NULL_TREE; | |
1377 | val.mask = double_int_minus_one; | |
1378 | return val; | |
1379 | } | |
1380 | ||
1381 | gcc_assert ((r1val.lattice_val == CONSTANT | |
1382 | && TREE_CODE (r1val.value) == INTEGER_CST) | |
1383 | || r1val.mask.is_minus_one ()); | |
1384 | gcc_assert ((r2val.lattice_val == CONSTANT | |
1385 | && TREE_CODE (r2val.value) == INTEGER_CST) | |
1386 | || r2val.mask.is_minus_one ()); | |
1387 | bit_value_binop_1 (code, type, &value, &mask, | |
1388 | TREE_TYPE (rhs1), value_to_double_int (r1val), r1val.mask, | |
1389 | TREE_TYPE (rhs2), value_to_double_int (r2val), r2val.mask); | |
1390 | if (!mask.is_minus_one ()) | |
1391 | { | |
1392 | val.lattice_val = CONSTANT; | |
1393 | val.mask = mask; | |
1394 | /* ??? Delay building trees here. */ | |
1395 | val.value = double_int_to_tree (type, value); | |
1396 | } | |
1397 | else | |
1398 | { | |
1399 | val.lattice_val = VARYING; | |
1400 | val.value = NULL_TREE; | |
1401 | val.mask = double_int_minus_one; | |
1402 | } | |
1403 | return val; | |
1404 | } | |
1405 | ||
1406 | /* Return the propagation value when applying __builtin_assume_aligned to | |
1407 | its arguments. */ | |
1408 | ||
1409 | static prop_value_t | |
1410 | bit_value_assume_aligned (gimple stmt) | |
1411 | { | |
1412 | tree ptr = gimple_call_arg (stmt, 0), align, misalign = NULL_TREE; | |
1413 | tree type = TREE_TYPE (ptr); | |
1414 | unsigned HOST_WIDE_INT aligni, misaligni = 0; | |
1415 | prop_value_t ptrval = get_value_for_expr (ptr, true); | |
1416 | prop_value_t alignval; | |
1417 | double_int value, mask; | |
1418 | prop_value_t val; | |
1419 | if (ptrval.lattice_val == UNDEFINED) | |
1420 | return ptrval; | |
1421 | gcc_assert ((ptrval.lattice_val == CONSTANT | |
1422 | && TREE_CODE (ptrval.value) == INTEGER_CST) | |
1423 | || ptrval.mask.is_minus_one ()); | |
1424 | align = gimple_call_arg (stmt, 1); | |
1425 | if (!host_integerp (align, 1)) | |
1426 | return ptrval; | |
1427 | aligni = tree_low_cst (align, 1); | |
1428 | if (aligni <= 1 | |
1429 | || (aligni & (aligni - 1)) != 0) | |
1430 | return ptrval; | |
1431 | if (gimple_call_num_args (stmt) > 2) | |
1432 | { | |
1433 | misalign = gimple_call_arg (stmt, 2); | |
1434 | if (!host_integerp (misalign, 1)) | |
1435 | return ptrval; | |
1436 | misaligni = tree_low_cst (misalign, 1); | |
1437 | if (misaligni >= aligni) | |
1438 | return ptrval; | |
1439 | } | |
1440 | align = build_int_cst_type (type, -aligni); | |
1441 | alignval = get_value_for_expr (align, true); | |
1442 | bit_value_binop_1 (BIT_AND_EXPR, type, &value, &mask, | |
1443 | type, value_to_double_int (ptrval), ptrval.mask, | |
1444 | type, value_to_double_int (alignval), alignval.mask); | |
1445 | if (!mask.is_minus_one ()) | |
1446 | { | |
1447 | val.lattice_val = CONSTANT; | |
1448 | val.mask = mask; | |
1449 | gcc_assert ((mask.low & (aligni - 1)) == 0); | |
1450 | gcc_assert ((value.low & (aligni - 1)) == 0); | |
1451 | value.low |= misaligni; | |
1452 | /* ??? Delay building trees here. */ | |
1453 | val.value = double_int_to_tree (type, value); | |
1454 | } | |
1455 | else | |
1456 | { | |
1457 | val.lattice_val = VARYING; | |
1458 | val.value = NULL_TREE; | |
1459 | val.mask = double_int_minus_one; | |
1460 | } | |
1461 | return val; | |
1462 | } | |
1463 | ||
1464 | /* Evaluate statement STMT. | |
1465 | Valid only for assignments, calls, conditionals, and switches. */ | |
1466 | ||
1467 | static prop_value_t | |
1468 | evaluate_stmt (gimple stmt) | |
1469 | { | |
1470 | prop_value_t val; | |
1471 | tree simplified = NULL_TREE; | |
1472 | ccp_lattice_t likelyvalue = likely_value (stmt); | |
1473 | bool is_constant = false; | |
1474 | unsigned int align; | |
1475 | ||
1476 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1477 | { | |
1478 | fprintf (dump_file, "which is likely "); | |
1479 | switch (likelyvalue) | |
1480 | { | |
1481 | case CONSTANT: | |
1482 | fprintf (dump_file, "CONSTANT"); | |
1483 | break; | |
1484 | case UNDEFINED: | |
1485 | fprintf (dump_file, "UNDEFINED"); | |
1486 | break; | |
1487 | case VARYING: | |
1488 | fprintf (dump_file, "VARYING"); | |
1489 | break; | |
1490 | default:; | |
1491 | } | |
1492 | fprintf (dump_file, "\n"); | |
1493 | } | |
1494 | ||
1495 | /* If the statement is likely to have a CONSTANT result, then try | |
1496 | to fold the statement to determine the constant value. */ | |
1497 | /* FIXME. This is the only place that we call ccp_fold. | |
1498 | Since likely_value never returns CONSTANT for calls, we will | |
1499 | not attempt to fold them, including builtins that may profit. */ | |
1500 | if (likelyvalue == CONSTANT) | |
1501 | { | |
1502 | fold_defer_overflow_warnings (); | |
1503 | simplified = ccp_fold (stmt); | |
1504 | is_constant = simplified && is_gimple_min_invariant (simplified); | |
1505 | fold_undefer_overflow_warnings (is_constant, stmt, 0); | |
1506 | if (is_constant) | |
1507 | { | |
1508 | /* The statement produced a constant value. */ | |
1509 | val.lattice_val = CONSTANT; | |
1510 | val.value = simplified; | |
1511 | val.mask = double_int_zero; | |
1512 | } | |
1513 | } | |
1514 | /* If the statement is likely to have a VARYING result, then do not | |
1515 | bother folding the statement. */ | |
1516 | else if (likelyvalue == VARYING) | |
1517 | { | |
1518 | enum gimple_code code = gimple_code (stmt); | |
1519 | if (code == GIMPLE_ASSIGN) | |
1520 | { | |
1521 | enum tree_code subcode = gimple_assign_rhs_code (stmt); | |
1522 | ||
1523 | /* Other cases cannot satisfy is_gimple_min_invariant | |
1524 | without folding. */ | |
1525 | if (get_gimple_rhs_class (subcode) == GIMPLE_SINGLE_RHS) | |
1526 | simplified = gimple_assign_rhs1 (stmt); | |
1527 | } | |
1528 | else if (code == GIMPLE_SWITCH) | |
1529 | simplified = gimple_switch_index (stmt); | |
1530 | else | |
1531 | /* These cannot satisfy is_gimple_min_invariant without folding. */ | |
1532 | gcc_assert (code == GIMPLE_CALL || code == GIMPLE_COND); | |
1533 | is_constant = simplified && is_gimple_min_invariant (simplified); | |
1534 | if (is_constant) | |
1535 | { | |
1536 | /* The statement produced a constant value. */ | |
1537 | val.lattice_val = CONSTANT; | |
1538 | val.value = simplified; | |
1539 | val.mask = double_int_zero; | |
1540 | } | |
1541 | } | |
1542 | ||
1543 | /* Resort to simplification for bitwise tracking. */ | |
1544 | if (flag_tree_bit_ccp | |
1545 | && (likelyvalue == CONSTANT || is_gimple_call (stmt)) | |
1546 | && !is_constant) | |
1547 | { | |
1548 | enum gimple_code code = gimple_code (stmt); | |
1549 | tree fndecl; | |
1550 | val.lattice_val = VARYING; | |
1551 | val.value = NULL_TREE; | |
1552 | val.mask = double_int_minus_one; | |
1553 | if (code == GIMPLE_ASSIGN) | |
1554 | { | |
1555 | enum tree_code subcode = gimple_assign_rhs_code (stmt); | |
1556 | tree rhs1 = gimple_assign_rhs1 (stmt); | |
1557 | switch (get_gimple_rhs_class (subcode)) | |
1558 | { | |
1559 | case GIMPLE_SINGLE_RHS: | |
1560 | if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1)) | |
1561 | || POINTER_TYPE_P (TREE_TYPE (rhs1))) | |
1562 | val = get_value_for_expr (rhs1, true); | |
1563 | break; | |
1564 | ||
1565 | case GIMPLE_UNARY_RHS: | |
1566 | if ((INTEGRAL_TYPE_P (TREE_TYPE (rhs1)) | |
1567 | || POINTER_TYPE_P (TREE_TYPE (rhs1))) | |
1568 | && (INTEGRAL_TYPE_P (gimple_expr_type (stmt)) | |
1569 | || POINTER_TYPE_P (gimple_expr_type (stmt)))) | |
1570 | val = bit_value_unop (subcode, gimple_expr_type (stmt), rhs1); | |
1571 | break; | |
1572 | ||
1573 | case GIMPLE_BINARY_RHS: | |
1574 | if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1)) | |
1575 | || POINTER_TYPE_P (TREE_TYPE (rhs1))) | |
1576 | { | |
1577 | tree lhs = gimple_assign_lhs (stmt); | |
1578 | tree rhs2 = gimple_assign_rhs2 (stmt); | |
1579 | val = bit_value_binop (subcode, | |
1580 | TREE_TYPE (lhs), rhs1, rhs2); | |
1581 | } | |
1582 | break; | |
1583 | ||
1584 | default:; | |
1585 | } | |
1586 | } | |
1587 | else if (code == GIMPLE_COND) | |
1588 | { | |
1589 | enum tree_code code = gimple_cond_code (stmt); | |
1590 | tree rhs1 = gimple_cond_lhs (stmt); | |
1591 | tree rhs2 = gimple_cond_rhs (stmt); | |
1592 | if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1)) | |
1593 | || POINTER_TYPE_P (TREE_TYPE (rhs1))) | |
1594 | val = bit_value_binop (code, TREE_TYPE (rhs1), rhs1, rhs2); | |
1595 | } | |
1596 | else if (code == GIMPLE_CALL | |
1597 | && (fndecl = gimple_call_fndecl (stmt)) | |
1598 | && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL) | |
1599 | { | |
1600 | switch (DECL_FUNCTION_CODE (fndecl)) | |
1601 | { | |
1602 | case BUILT_IN_MALLOC: | |
1603 | case BUILT_IN_REALLOC: | |
1604 | case BUILT_IN_CALLOC: | |
1605 | case BUILT_IN_STRDUP: | |
1606 | case BUILT_IN_STRNDUP: | |
1607 | val.lattice_val = CONSTANT; | |
1608 | val.value = build_int_cst (TREE_TYPE (gimple_get_lhs (stmt)), 0); | |
1609 | val.mask = double_int::from_shwi | |
1610 | (~(((HOST_WIDE_INT) MALLOC_ABI_ALIGNMENT) | |
1611 | / BITS_PER_UNIT - 1)); | |
1612 | break; | |
1613 | ||
1614 | case BUILT_IN_ALLOCA: | |
1615 | case BUILT_IN_ALLOCA_WITH_ALIGN: | |
1616 | align = (DECL_FUNCTION_CODE (fndecl) == BUILT_IN_ALLOCA_WITH_ALIGN | |
1617 | ? TREE_INT_CST_LOW (gimple_call_arg (stmt, 1)) | |
1618 | : BIGGEST_ALIGNMENT); | |
1619 | val.lattice_val = CONSTANT; | |
1620 | val.value = build_int_cst (TREE_TYPE (gimple_get_lhs (stmt)), 0); | |
1621 | val.mask = double_int::from_shwi (~(((HOST_WIDE_INT) align) | |
1622 | / BITS_PER_UNIT - 1)); | |
1623 | break; | |
1624 | ||
1625 | /* These builtins return their first argument, unmodified. */ | |
1626 | case BUILT_IN_MEMCPY: | |
1627 | case BUILT_IN_MEMMOVE: | |
1628 | case BUILT_IN_MEMSET: | |
1629 | case BUILT_IN_STRCPY: | |
1630 | case BUILT_IN_STRNCPY: | |
1631 | case BUILT_IN_MEMCPY_CHK: | |
1632 | case BUILT_IN_MEMMOVE_CHK: | |
1633 | case BUILT_IN_MEMSET_CHK: | |
1634 | case BUILT_IN_STRCPY_CHK: | |
1635 | case BUILT_IN_STRNCPY_CHK: | |
1636 | val = get_value_for_expr (gimple_call_arg (stmt, 0), true); | |
1637 | break; | |
1638 | ||
1639 | case BUILT_IN_ASSUME_ALIGNED: | |
1640 | val = bit_value_assume_aligned (stmt); | |
1641 | break; | |
1642 | ||
1643 | default:; | |
1644 | } | |
1645 | } | |
1646 | is_constant = (val.lattice_val == CONSTANT); | |
1647 | } | |
1648 | ||
1649 | if (!is_constant) | |
1650 | { | |
1651 | /* The statement produced a nonconstant value. If the statement | |
1652 | had UNDEFINED operands, then the result of the statement | |
1653 | should be UNDEFINED. Otherwise, the statement is VARYING. */ | |
1654 | if (likelyvalue == UNDEFINED) | |
1655 | { | |
1656 | val.lattice_val = likelyvalue; | |
1657 | val.mask = double_int_zero; | |
1658 | } | |
1659 | else | |
1660 | { | |
1661 | val.lattice_val = VARYING; | |
1662 | val.mask = double_int_minus_one; | |
1663 | } | |
1664 | ||
1665 | val.value = NULL_TREE; | |
1666 | } | |
1667 | ||
1668 | return val; | |
1669 | } | |
1670 | ||
1671 | typedef hash_table <pointer_hash <gimple_statement_d> > gimple_htab; | |
1672 | ||
1673 | /* Given a BUILT_IN_STACK_SAVE value SAVED_VAL, insert a clobber of VAR before | |
1674 | each matching BUILT_IN_STACK_RESTORE. Mark visited phis in VISITED. */ | |
1675 | ||
1676 | static void | |
1677 | insert_clobber_before_stack_restore (tree saved_val, tree var, | |
1678 | gimple_htab *visited) | |
1679 | { | |
1680 | gimple stmt, clobber_stmt; | |
1681 | tree clobber; | |
1682 | imm_use_iterator iter; | |
1683 | gimple_stmt_iterator i; | |
1684 | gimple *slot; | |
1685 | ||
1686 | FOR_EACH_IMM_USE_STMT (stmt, iter, saved_val) | |
1687 | if (gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE)) | |
1688 | { | |
1689 | clobber = build_constructor (TREE_TYPE (var), | |
1690 | NULL); | |
1691 | TREE_THIS_VOLATILE (clobber) = 1; | |
1692 | clobber_stmt = gimple_build_assign (var, clobber); | |
1693 | ||
1694 | i = gsi_for_stmt (stmt); | |
1695 | gsi_insert_before (&i, clobber_stmt, GSI_SAME_STMT); | |
1696 | } | |
1697 | else if (gimple_code (stmt) == GIMPLE_PHI) | |
1698 | { | |
1699 | if (!visited->is_created ()) | |
1700 | visited->create (10); | |
1701 | ||
1702 | slot = visited->find_slot (stmt, INSERT); | |
1703 | if (*slot != NULL) | |
1704 | continue; | |
1705 | ||
1706 | *slot = stmt; | |
1707 | insert_clobber_before_stack_restore (gimple_phi_result (stmt), var, | |
1708 | visited); | |
1709 | } | |
1710 | else | |
1711 | gcc_assert (is_gimple_debug (stmt)); | |
1712 | } | |
1713 | ||
1714 | /* Advance the iterator to the previous non-debug gimple statement in the same | |
1715 | or dominating basic block. */ | |
1716 | ||
1717 | static inline void | |
1718 | gsi_prev_dom_bb_nondebug (gimple_stmt_iterator *i) | |
1719 | { | |
1720 | basic_block dom; | |
1721 | ||
1722 | gsi_prev_nondebug (i); | |
1723 | while (gsi_end_p (*i)) | |
1724 | { | |
1725 | dom = get_immediate_dominator (CDI_DOMINATORS, i->bb); | |
1726 | if (dom == NULL || dom == ENTRY_BLOCK_PTR) | |
1727 | return; | |
1728 | ||
1729 | *i = gsi_last_bb (dom); | |
1730 | } | |
1731 | } | |
1732 | ||
1733 | /* Find a BUILT_IN_STACK_SAVE dominating gsi_stmt (I), and insert | |
1734 | a clobber of VAR before each matching BUILT_IN_STACK_RESTORE. | |
1735 | ||
1736 | It is possible that BUILT_IN_STACK_SAVE cannot be find in a dominator when a | |
1737 | previous pass (such as DOM) duplicated it along multiple paths to a BB. In | |
1738 | that case the function gives up without inserting the clobbers. */ | |
1739 | ||
1740 | static void | |
1741 | insert_clobbers_for_var (gimple_stmt_iterator i, tree var) | |
1742 | { | |
1743 | gimple stmt; | |
1744 | tree saved_val; | |
1745 | gimple_htab visited; | |
1746 | ||
1747 | for (; !gsi_end_p (i); gsi_prev_dom_bb_nondebug (&i)) | |
1748 | { | |
1749 | stmt = gsi_stmt (i); | |
1750 | ||
1751 | if (!gimple_call_builtin_p (stmt, BUILT_IN_STACK_SAVE)) | |
1752 | continue; | |
1753 | ||
1754 | saved_val = gimple_call_lhs (stmt); | |
1755 | if (saved_val == NULL_TREE) | |
1756 | continue; | |
1757 | ||
1758 | insert_clobber_before_stack_restore (saved_val, var, &visited); | |
1759 | break; | |
1760 | } | |
1761 | ||
1762 | if (visited.is_created ()) | |
1763 | visited.dispose (); | |
1764 | } | |
1765 | ||
1766 | /* Detects a __builtin_alloca_with_align with constant size argument. Declares | |
1767 | fixed-size array and returns the address, if found, otherwise returns | |
1768 | NULL_TREE. */ | |
1769 | ||
1770 | static tree | |
1771 | fold_builtin_alloca_with_align (gimple stmt) | |
1772 | { | |
1773 | unsigned HOST_WIDE_INT size, threshold, n_elem; | |
1774 | tree lhs, arg, block, var, elem_type, array_type; | |
1775 | ||
1776 | /* Get lhs. */ | |
1777 | lhs = gimple_call_lhs (stmt); | |
1778 | if (lhs == NULL_TREE) | |
1779 | return NULL_TREE; | |
1780 | ||
1781 | /* Detect constant argument. */ | |
1782 | arg = get_constant_value (gimple_call_arg (stmt, 0)); | |
1783 | if (arg == NULL_TREE | |
1784 | || TREE_CODE (arg) != INTEGER_CST | |
1785 | || !host_integerp (arg, 1)) | |
1786 | return NULL_TREE; | |
1787 | ||
1788 | size = TREE_INT_CST_LOW (arg); | |
1789 | ||
1790 | /* Heuristic: don't fold large allocas. */ | |
1791 | threshold = (unsigned HOST_WIDE_INT)PARAM_VALUE (PARAM_LARGE_STACK_FRAME); | |
1792 | /* In case the alloca is located at function entry, it has the same lifetime | |
1793 | as a declared array, so we allow a larger size. */ | |
1794 | block = gimple_block (stmt); | |
1795 | if (!(cfun->after_inlining | |
1796 | && TREE_CODE (BLOCK_SUPERCONTEXT (block)) == FUNCTION_DECL)) | |
1797 | threshold /= 10; | |
1798 | if (size > threshold) | |
1799 | return NULL_TREE; | |
1800 | ||
1801 | /* Declare array. */ | |
1802 | elem_type = build_nonstandard_integer_type (BITS_PER_UNIT, 1); | |
1803 | n_elem = size * 8 / BITS_PER_UNIT; | |
1804 | array_type = build_array_type_nelts (elem_type, n_elem); | |
1805 | var = create_tmp_var (array_type, NULL); | |
1806 | DECL_ALIGN (var) = TREE_INT_CST_LOW (gimple_call_arg (stmt, 1)); | |
1807 | { | |
1808 | struct ptr_info_def *pi = SSA_NAME_PTR_INFO (lhs); | |
1809 | if (pi != NULL && !pi->pt.anything) | |
1810 | { | |
1811 | bool singleton_p; | |
1812 | unsigned uid; | |
1813 | singleton_p = pt_solution_singleton_p (&pi->pt, &uid); | |
1814 | gcc_assert (singleton_p); | |
1815 | SET_DECL_PT_UID (var, uid); | |
1816 | } | |
1817 | } | |
1818 | ||
1819 | /* Fold alloca to the address of the array. */ | |
1820 | return fold_convert (TREE_TYPE (lhs), build_fold_addr_expr (var)); | |
1821 | } | |
1822 | ||
1823 | /* Fold the stmt at *GSI with CCP specific information that propagating | |
1824 | and regular folding does not catch. */ | |
1825 | ||
1826 | static bool | |
1827 | ccp_fold_stmt (gimple_stmt_iterator *gsi) | |
1828 | { | |
1829 | gimple stmt = gsi_stmt (*gsi); | |
1830 | ||
1831 | switch (gimple_code (stmt)) | |
1832 | { | |
1833 | case GIMPLE_COND: | |
1834 | { | |
1835 | prop_value_t val; | |
1836 | /* Statement evaluation will handle type mismatches in constants | |
1837 | more gracefully than the final propagation. This allows us to | |
1838 | fold more conditionals here. */ | |
1839 | val = evaluate_stmt (stmt); | |
1840 | if (val.lattice_val != CONSTANT | |
1841 | || !val.mask.is_zero ()) | |
1842 | return false; | |
1843 | ||
1844 | if (dump_file) | |
1845 | { | |
1846 | fprintf (dump_file, "Folding predicate "); | |
1847 | print_gimple_expr (dump_file, stmt, 0, 0); | |
1848 | fprintf (dump_file, " to "); | |
1849 | print_generic_expr (dump_file, val.value, 0); | |
1850 | fprintf (dump_file, "\n"); | |
1851 | } | |
1852 | ||
1853 | if (integer_zerop (val.value)) | |
1854 | gimple_cond_make_false (stmt); | |
1855 | else | |
1856 | gimple_cond_make_true (stmt); | |
1857 | ||
1858 | return true; | |
1859 | } | |
1860 | ||
1861 | case GIMPLE_CALL: | |
1862 | { | |
1863 | tree lhs = gimple_call_lhs (stmt); | |
1864 | int flags = gimple_call_flags (stmt); | |
1865 | tree val; | |
1866 | tree argt; | |
1867 | bool changed = false; | |
1868 | unsigned i; | |
1869 | ||
1870 | /* If the call was folded into a constant make sure it goes | |
1871 | away even if we cannot propagate into all uses because of | |
1872 | type issues. */ | |
1873 | if (lhs | |
1874 | && TREE_CODE (lhs) == SSA_NAME | |
1875 | && (val = get_constant_value (lhs)) | |
1876 | /* Don't optimize away calls that have side-effects. */ | |
1877 | && (flags & (ECF_CONST|ECF_PURE)) != 0 | |
1878 | && (flags & ECF_LOOPING_CONST_OR_PURE) == 0) | |
1879 | { | |
1880 | tree new_rhs = unshare_expr (val); | |
1881 | bool res; | |
1882 | if (!useless_type_conversion_p (TREE_TYPE (lhs), | |
1883 | TREE_TYPE (new_rhs))) | |
1884 | new_rhs = fold_convert (TREE_TYPE (lhs), new_rhs); | |
1885 | res = update_call_from_tree (gsi, new_rhs); | |
1886 | gcc_assert (res); | |
1887 | return true; | |
1888 | } | |
1889 | ||
1890 | /* Internal calls provide no argument types, so the extra laxity | |
1891 | for normal calls does not apply. */ | |
1892 | if (gimple_call_internal_p (stmt)) | |
1893 | return false; | |
1894 | ||
1895 | /* The heuristic of fold_builtin_alloca_with_align differs before and | |
1896 | after inlining, so we don't require the arg to be changed into a | |
1897 | constant for folding, but just to be constant. */ | |
1898 | if (gimple_call_builtin_p (stmt, BUILT_IN_ALLOCA_WITH_ALIGN)) | |
1899 | { | |
1900 | tree new_rhs = fold_builtin_alloca_with_align (stmt); | |
1901 | if (new_rhs) | |
1902 | { | |
1903 | bool res = update_call_from_tree (gsi, new_rhs); | |
1904 | tree var = TREE_OPERAND (TREE_OPERAND (new_rhs, 0),0); | |
1905 | gcc_assert (res); | |
1906 | insert_clobbers_for_var (*gsi, var); | |
1907 | return true; | |
1908 | } | |
1909 | } | |
1910 | ||
1911 | /* Propagate into the call arguments. Compared to replace_uses_in | |
1912 | this can use the argument slot types for type verification | |
1913 | instead of the current argument type. We also can safely | |
1914 | drop qualifiers here as we are dealing with constants anyway. */ | |
1915 | argt = TYPE_ARG_TYPES (gimple_call_fntype (stmt)); | |
1916 | for (i = 0; i < gimple_call_num_args (stmt) && argt; | |
1917 | ++i, argt = TREE_CHAIN (argt)) | |
1918 | { | |
1919 | tree arg = gimple_call_arg (stmt, i); | |
1920 | if (TREE_CODE (arg) == SSA_NAME | |
1921 | && (val = get_constant_value (arg)) | |
1922 | && useless_type_conversion_p | |
1923 | (TYPE_MAIN_VARIANT (TREE_VALUE (argt)), | |
1924 | TYPE_MAIN_VARIANT (TREE_TYPE (val)))) | |
1925 | { | |
1926 | gimple_call_set_arg (stmt, i, unshare_expr (val)); | |
1927 | changed = true; | |
1928 | } | |
1929 | } | |
1930 | ||
1931 | return changed; | |
1932 | } | |
1933 | ||
1934 | case GIMPLE_ASSIGN: | |
1935 | { | |
1936 | tree lhs = gimple_assign_lhs (stmt); | |
1937 | tree val; | |
1938 | ||
1939 | /* If we have a load that turned out to be constant replace it | |
1940 | as we cannot propagate into all uses in all cases. */ | |
1941 | if (gimple_assign_single_p (stmt) | |
1942 | && TREE_CODE (lhs) == SSA_NAME | |
1943 | && (val = get_constant_value (lhs))) | |
1944 | { | |
1945 | tree rhs = unshare_expr (val); | |
1946 | if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (rhs))) | |
1947 | rhs = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (lhs), rhs); | |
1948 | gimple_assign_set_rhs_from_tree (gsi, rhs); | |
1949 | return true; | |
1950 | } | |
1951 | ||
1952 | return false; | |
1953 | } | |
1954 | ||
1955 | default: | |
1956 | return false; | |
1957 | } | |
1958 | } | |
1959 | ||
1960 | /* Visit the assignment statement STMT. Set the value of its LHS to the | |
1961 | value computed by the RHS and store LHS in *OUTPUT_P. If STMT | |
1962 | creates virtual definitions, set the value of each new name to that | |
1963 | of the RHS (if we can derive a constant out of the RHS). | |
1964 | Value-returning call statements also perform an assignment, and | |
1965 | are handled here. */ | |
1966 | ||
1967 | static enum ssa_prop_result | |
1968 | visit_assignment (gimple stmt, tree *output_p) | |
1969 | { | |
1970 | prop_value_t val; | |
1971 | enum ssa_prop_result retval; | |
1972 | ||
1973 | tree lhs = gimple_get_lhs (stmt); | |
1974 | ||
1975 | gcc_assert (gimple_code (stmt) != GIMPLE_CALL | |
1976 | || gimple_call_lhs (stmt) != NULL_TREE); | |
1977 | ||
1978 | if (gimple_assign_single_p (stmt) | |
1979 | && gimple_assign_rhs_code (stmt) == SSA_NAME) | |
1980 | /* For a simple copy operation, we copy the lattice values. */ | |
1981 | val = *get_value (gimple_assign_rhs1 (stmt)); | |
1982 | else | |
1983 | /* Evaluate the statement, which could be | |
1984 | either a GIMPLE_ASSIGN or a GIMPLE_CALL. */ | |
1985 | val = evaluate_stmt (stmt); | |
1986 | ||
1987 | retval = SSA_PROP_NOT_INTERESTING; | |
1988 | ||
1989 | /* Set the lattice value of the statement's output. */ | |
1990 | if (TREE_CODE (lhs) == SSA_NAME) | |
1991 | { | |
1992 | /* If STMT is an assignment to an SSA_NAME, we only have one | |
1993 | value to set. */ | |
1994 | if (set_lattice_value (lhs, val)) | |
1995 | { | |
1996 | *output_p = lhs; | |
1997 | if (val.lattice_val == VARYING) | |
1998 | retval = SSA_PROP_VARYING; | |
1999 | else | |
2000 | retval = SSA_PROP_INTERESTING; | |
2001 | } | |
2002 | } | |
2003 | ||
2004 | return retval; | |
2005 | } | |
2006 | ||
2007 | ||
2008 | /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING | |
2009 | if it can determine which edge will be taken. Otherwise, return | |
2010 | SSA_PROP_VARYING. */ | |
2011 | ||
2012 | static enum ssa_prop_result | |
2013 | visit_cond_stmt (gimple stmt, edge *taken_edge_p) | |
2014 | { | |
2015 | prop_value_t val; | |
2016 | basic_block block; | |
2017 | ||
2018 | block = gimple_bb (stmt); | |
2019 | val = evaluate_stmt (stmt); | |
2020 | if (val.lattice_val != CONSTANT | |
2021 | || !val.mask.is_zero ()) | |
2022 | return SSA_PROP_VARYING; | |
2023 | ||
2024 | /* Find which edge out of the conditional block will be taken and add it | |
2025 | to the worklist. If no single edge can be determined statically, | |
2026 | return SSA_PROP_VARYING to feed all the outgoing edges to the | |
2027 | propagation engine. */ | |
2028 | *taken_edge_p = find_taken_edge (block, val.value); | |
2029 | if (*taken_edge_p) | |
2030 | return SSA_PROP_INTERESTING; | |
2031 | else | |
2032 | return SSA_PROP_VARYING; | |
2033 | } | |
2034 | ||
2035 | ||
2036 | /* Evaluate statement STMT. If the statement produces an output value and | |
2037 | its evaluation changes the lattice value of its output, return | |
2038 | SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the | |
2039 | output value. | |
2040 | ||
2041 | If STMT is a conditional branch and we can determine its truth | |
2042 | value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying | |
2043 | value, return SSA_PROP_VARYING. */ | |
2044 | ||
2045 | static enum ssa_prop_result | |
2046 | ccp_visit_stmt (gimple stmt, edge *taken_edge_p, tree *output_p) | |
2047 | { | |
2048 | tree def; | |
2049 | ssa_op_iter iter; | |
2050 | ||
2051 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2052 | { | |
2053 | fprintf (dump_file, "\nVisiting statement:\n"); | |
2054 | print_gimple_stmt (dump_file, stmt, 0, dump_flags); | |
2055 | } | |
2056 | ||
2057 | switch (gimple_code (stmt)) | |
2058 | { | |
2059 | case GIMPLE_ASSIGN: | |
2060 | /* If the statement is an assignment that produces a single | |
2061 | output value, evaluate its RHS to see if the lattice value of | |
2062 | its output has changed. */ | |
2063 | return visit_assignment (stmt, output_p); | |
2064 | ||
2065 | case GIMPLE_CALL: | |
2066 | /* A value-returning call also performs an assignment. */ | |
2067 | if (gimple_call_lhs (stmt) != NULL_TREE) | |
2068 | return visit_assignment (stmt, output_p); | |
2069 | break; | |
2070 | ||
2071 | case GIMPLE_COND: | |
2072 | case GIMPLE_SWITCH: | |
2073 | /* If STMT is a conditional branch, see if we can determine | |
2074 | which branch will be taken. */ | |
2075 | /* FIXME. It appears that we should be able to optimize | |
2076 | computed GOTOs here as well. */ | |
2077 | return visit_cond_stmt (stmt, taken_edge_p); | |
2078 | ||
2079 | default: | |
2080 | break; | |
2081 | } | |
2082 | ||
2083 | /* Any other kind of statement is not interesting for constant | |
2084 | propagation and, therefore, not worth simulating. */ | |
2085 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2086 | fprintf (dump_file, "No interesting values produced. Marked VARYING.\n"); | |
2087 | ||
2088 | /* Definitions made by statements other than assignments to | |
2089 | SSA_NAMEs represent unknown modifications to their outputs. | |
2090 | Mark them VARYING. */ | |
2091 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) | |
2092 | { | |
2093 | prop_value_t v = { VARYING, NULL_TREE, { -1, (HOST_WIDE_INT) -1 } }; | |
2094 | set_lattice_value (def, v); | |
2095 | } | |
2096 | ||
2097 | return SSA_PROP_VARYING; | |
2098 | } | |
2099 | ||
2100 | ||
2101 | /* Main entry point for SSA Conditional Constant Propagation. */ | |
2102 | ||
2103 | static unsigned int | |
2104 | do_ssa_ccp (void) | |
2105 | { | |
2106 | unsigned int todo = 0; | |
2107 | calculate_dominance_info (CDI_DOMINATORS); | |
2108 | ccp_initialize (); | |
2109 | ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node); | |
2110 | if (ccp_finalize ()) | |
2111 | todo = (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals); | |
2112 | free_dominance_info (CDI_DOMINATORS); | |
2113 | return todo; | |
2114 | } | |
2115 | ||
2116 | ||
2117 | static bool | |
2118 | gate_ccp (void) | |
2119 | { | |
2120 | return flag_tree_ccp != 0; | |
2121 | } | |
2122 | ||
2123 | ||
2124 | struct gimple_opt_pass pass_ccp = | |
2125 | { | |
2126 | { | |
2127 | GIMPLE_PASS, | |
2128 | "ccp", /* name */ | |
2129 | OPTGROUP_NONE, /* optinfo_flags */ | |
2130 | gate_ccp, /* gate */ | |
2131 | do_ssa_ccp, /* execute */ | |
2132 | NULL, /* sub */ | |
2133 | NULL, /* next */ | |
2134 | 0, /* static_pass_number */ | |
2135 | TV_TREE_CCP, /* tv_id */ | |
2136 | PROP_cfg | PROP_ssa, /* properties_required */ | |
2137 | 0, /* properties_provided */ | |
2138 | 0, /* properties_destroyed */ | |
2139 | 0, /* todo_flags_start */ | |
2140 | TODO_verify_ssa | |
2141 | | TODO_update_address_taken | |
2142 | | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */ | |
2143 | } | |
2144 | }; | |
2145 | ||
2146 | ||
2147 | ||
2148 | /* Try to optimize out __builtin_stack_restore. Optimize it out | |
2149 | if there is another __builtin_stack_restore in the same basic | |
2150 | block and no calls or ASM_EXPRs are in between, or if this block's | |
2151 | only outgoing edge is to EXIT_BLOCK and there are no calls or | |
2152 | ASM_EXPRs after this __builtin_stack_restore. */ | |
2153 | ||
2154 | static tree | |
2155 | optimize_stack_restore (gimple_stmt_iterator i) | |
2156 | { | |
2157 | tree callee; | |
2158 | gimple stmt; | |
2159 | ||
2160 | basic_block bb = gsi_bb (i); | |
2161 | gimple call = gsi_stmt (i); | |
2162 | ||
2163 | if (gimple_code (call) != GIMPLE_CALL | |
2164 | || gimple_call_num_args (call) != 1 | |
2165 | || TREE_CODE (gimple_call_arg (call, 0)) != SSA_NAME | |
2166 | || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call, 0)))) | |
2167 | return NULL_TREE; | |
2168 | ||
2169 | for (gsi_next (&i); !gsi_end_p (i); gsi_next (&i)) | |
2170 | { | |
2171 | stmt = gsi_stmt (i); | |
2172 | if (gimple_code (stmt) == GIMPLE_ASM) | |
2173 | return NULL_TREE; | |
2174 | if (gimple_code (stmt) != GIMPLE_CALL) | |
2175 | continue; | |
2176 | ||
2177 | callee = gimple_call_fndecl (stmt); | |
2178 | if (!callee | |
2179 | || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL | |
2180 | /* All regular builtins are ok, just obviously not alloca. */ | |
2181 | || DECL_FUNCTION_CODE (callee) == BUILT_IN_ALLOCA | |
2182 | || DECL_FUNCTION_CODE (callee) == BUILT_IN_ALLOCA_WITH_ALIGN) | |
2183 | return NULL_TREE; | |
2184 | ||
2185 | if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE) | |
2186 | goto second_stack_restore; | |
2187 | } | |
2188 | ||
2189 | if (!gsi_end_p (i)) | |
2190 | return NULL_TREE; | |
2191 | ||
2192 | /* Allow one successor of the exit block, or zero successors. */ | |
2193 | switch (EDGE_COUNT (bb->succs)) | |
2194 | { | |
2195 | case 0: | |
2196 | break; | |
2197 | case 1: | |
2198 | if (single_succ_edge (bb)->dest != EXIT_BLOCK_PTR) | |
2199 | return NULL_TREE; | |
2200 | break; | |
2201 | default: | |
2202 | return NULL_TREE; | |
2203 | } | |
2204 | second_stack_restore: | |
2205 | ||
2206 | /* If there's exactly one use, then zap the call to __builtin_stack_save. | |
2207 | If there are multiple uses, then the last one should remove the call. | |
2208 | In any case, whether the call to __builtin_stack_save can be removed | |
2209 | or not is irrelevant to removing the call to __builtin_stack_restore. */ | |
2210 | if (has_single_use (gimple_call_arg (call, 0))) | |
2211 | { | |
2212 | gimple stack_save = SSA_NAME_DEF_STMT (gimple_call_arg (call, 0)); | |
2213 | if (is_gimple_call (stack_save)) | |
2214 | { | |
2215 | callee = gimple_call_fndecl (stack_save); | |
2216 | if (callee | |
2217 | && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL | |
2218 | && DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_SAVE) | |
2219 | { | |
2220 | gimple_stmt_iterator stack_save_gsi; | |
2221 | tree rhs; | |
2222 | ||
2223 | stack_save_gsi = gsi_for_stmt (stack_save); | |
2224 | rhs = build_int_cst (TREE_TYPE (gimple_call_arg (call, 0)), 0); | |
2225 | update_call_from_tree (&stack_save_gsi, rhs); | |
2226 | } | |
2227 | } | |
2228 | } | |
2229 | ||
2230 | /* No effect, so the statement will be deleted. */ | |
2231 | return integer_zero_node; | |
2232 | } | |
2233 | ||
2234 | /* If va_list type is a simple pointer and nothing special is needed, | |
2235 | optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0), | |
2236 | __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple | |
2237 | pointer assignment. */ | |
2238 | ||
2239 | static tree | |
2240 | optimize_stdarg_builtin (gimple call) | |
2241 | { | |
2242 | tree callee, lhs, rhs, cfun_va_list; | |
2243 | bool va_list_simple_ptr; | |
2244 | location_t loc = gimple_location (call); | |
2245 | ||
2246 | if (gimple_code (call) != GIMPLE_CALL) | |
2247 | return NULL_TREE; | |
2248 | ||
2249 | callee = gimple_call_fndecl (call); | |
2250 | ||
2251 | cfun_va_list = targetm.fn_abi_va_list (callee); | |
2252 | va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list) | |
2253 | && (TREE_TYPE (cfun_va_list) == void_type_node | |
2254 | || TREE_TYPE (cfun_va_list) == char_type_node); | |
2255 | ||
2256 | switch (DECL_FUNCTION_CODE (callee)) | |
2257 | { | |
2258 | case BUILT_IN_VA_START: | |
2259 | if (!va_list_simple_ptr | |
2260 | || targetm.expand_builtin_va_start != NULL | |
2261 | || !builtin_decl_explicit_p (BUILT_IN_NEXT_ARG)) | |
2262 | return NULL_TREE; | |
2263 | ||
2264 | if (gimple_call_num_args (call) != 2) | |
2265 | return NULL_TREE; | |
2266 | ||
2267 | lhs = gimple_call_arg (call, 0); | |
2268 | if (!POINTER_TYPE_P (TREE_TYPE (lhs)) | |
2269 | || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs))) | |
2270 | != TYPE_MAIN_VARIANT (cfun_va_list)) | |
2271 | return NULL_TREE; | |
2272 | ||
2273 | lhs = build_fold_indirect_ref_loc (loc, lhs); | |
2274 | rhs = build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_NEXT_ARG), | |
2275 | 1, integer_zero_node); | |
2276 | rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs); | |
2277 | return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs); | |
2278 | ||
2279 | case BUILT_IN_VA_COPY: | |
2280 | if (!va_list_simple_ptr) | |
2281 | return NULL_TREE; | |
2282 | ||
2283 | if (gimple_call_num_args (call) != 2) | |
2284 | return NULL_TREE; | |
2285 | ||
2286 | lhs = gimple_call_arg (call, 0); | |
2287 | if (!POINTER_TYPE_P (TREE_TYPE (lhs)) | |
2288 | || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs))) | |
2289 | != TYPE_MAIN_VARIANT (cfun_va_list)) | |
2290 | return NULL_TREE; | |
2291 | ||
2292 | lhs = build_fold_indirect_ref_loc (loc, lhs); | |
2293 | rhs = gimple_call_arg (call, 1); | |
2294 | if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs)) | |
2295 | != TYPE_MAIN_VARIANT (cfun_va_list)) | |
2296 | return NULL_TREE; | |
2297 | ||
2298 | rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs); | |
2299 | return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs); | |
2300 | ||
2301 | case BUILT_IN_VA_END: | |
2302 | /* No effect, so the statement will be deleted. */ | |
2303 | return integer_zero_node; | |
2304 | ||
2305 | default: | |
2306 | gcc_unreachable (); | |
2307 | } | |
2308 | } | |
2309 | ||
2310 | /* Attemp to make the block of __builtin_unreachable I unreachable by changing | |
2311 | the incoming jumps. Return true if at least one jump was changed. */ | |
2312 | ||
2313 | static bool | |
2314 | optimize_unreachable (gimple_stmt_iterator i) | |
2315 | { | |
2316 | basic_block bb = gsi_bb (i); | |
2317 | gimple_stmt_iterator gsi; | |
2318 | gimple stmt; | |
2319 | edge_iterator ei; | |
2320 | edge e; | |
2321 | bool ret; | |
2322 | ||
2323 | for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
2324 | { | |
2325 | stmt = gsi_stmt (gsi); | |
2326 | ||
2327 | if (is_gimple_debug (stmt)) | |
2328 | continue; | |
2329 | ||
2330 | if (gimple_code (stmt) == GIMPLE_LABEL) | |
2331 | { | |
2332 | /* Verify we do not need to preserve the label. */ | |
2333 | if (FORCED_LABEL (gimple_label_label (stmt))) | |
2334 | return false; | |
2335 | ||
2336 | continue; | |
2337 | } | |
2338 | ||
2339 | /* Only handle the case that __builtin_unreachable is the first statement | |
2340 | in the block. We rely on DCE to remove stmts without side-effects | |
2341 | before __builtin_unreachable. */ | |
2342 | if (gsi_stmt (gsi) != gsi_stmt (i)) | |
2343 | return false; | |
2344 | } | |
2345 | ||
2346 | ret = false; | |
2347 | FOR_EACH_EDGE (e, ei, bb->preds) | |
2348 | { | |
2349 | gsi = gsi_last_bb (e->src); | |
2350 | if (gsi_end_p (gsi)) | |
2351 | continue; | |
2352 | ||
2353 | stmt = gsi_stmt (gsi); | |
2354 | if (gimple_code (stmt) == GIMPLE_COND) | |
2355 | { | |
2356 | if (e->flags & EDGE_TRUE_VALUE) | |
2357 | gimple_cond_make_false (stmt); | |
2358 | else if (e->flags & EDGE_FALSE_VALUE) | |
2359 | gimple_cond_make_true (stmt); | |
2360 | else | |
2361 | gcc_unreachable (); | |
2362 | update_stmt (stmt); | |
2363 | } | |
2364 | else | |
2365 | { | |
2366 | /* Todo: handle other cases, f.i. switch statement. */ | |
2367 | continue; | |
2368 | } | |
2369 | ||
2370 | ret = true; | |
2371 | } | |
2372 | ||
2373 | return ret; | |
2374 | } | |
2375 | ||
2376 | /* A simple pass that attempts to fold all builtin functions. This pass | |
2377 | is run after we've propagated as many constants as we can. */ | |
2378 | ||
2379 | static unsigned int | |
2380 | execute_fold_all_builtins (void) | |
2381 | { | |
2382 | bool cfg_changed = false; | |
2383 | basic_block bb; | |
2384 | unsigned int todoflags = 0; | |
2385 | ||
2386 | FOR_EACH_BB (bb) | |
2387 | { | |
2388 | gimple_stmt_iterator i; | |
2389 | for (i = gsi_start_bb (bb); !gsi_end_p (i); ) | |
2390 | { | |
2391 | gimple stmt, old_stmt; | |
2392 | tree callee, result; | |
2393 | enum built_in_function fcode; | |
2394 | ||
2395 | stmt = gsi_stmt (i); | |
2396 | ||
2397 | if (gimple_code (stmt) != GIMPLE_CALL) | |
2398 | { | |
2399 | gsi_next (&i); | |
2400 | continue; | |
2401 | } | |
2402 | callee = gimple_call_fndecl (stmt); | |
2403 | if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL) | |
2404 | { | |
2405 | gsi_next (&i); | |
2406 | continue; | |
2407 | } | |
2408 | fcode = DECL_FUNCTION_CODE (callee); | |
2409 | ||
2410 | result = gimple_fold_builtin (stmt); | |
2411 | ||
2412 | if (result) | |
2413 | gimple_remove_stmt_histograms (cfun, stmt); | |
2414 | ||
2415 | if (!result) | |
2416 | switch (DECL_FUNCTION_CODE (callee)) | |
2417 | { | |
2418 | case BUILT_IN_CONSTANT_P: | |
2419 | /* Resolve __builtin_constant_p. If it hasn't been | |
2420 | folded to integer_one_node by now, it's fairly | |
2421 | certain that the value simply isn't constant. */ | |
2422 | result = integer_zero_node; | |
2423 | break; | |
2424 | ||
2425 | case BUILT_IN_ASSUME_ALIGNED: | |
2426 | /* Remove __builtin_assume_aligned. */ | |
2427 | result = gimple_call_arg (stmt, 0); | |
2428 | break; | |
2429 | ||
2430 | case BUILT_IN_STACK_RESTORE: | |
2431 | result = optimize_stack_restore (i); | |
2432 | if (result) | |
2433 | break; | |
2434 | gsi_next (&i); | |
2435 | continue; | |
2436 | ||
2437 | case BUILT_IN_UNREACHABLE: | |
2438 | if (optimize_unreachable (i)) | |
2439 | cfg_changed = true; | |
2440 | break; | |
2441 | ||
2442 | case BUILT_IN_VA_START: | |
2443 | case BUILT_IN_VA_END: | |
2444 | case BUILT_IN_VA_COPY: | |
2445 | /* These shouldn't be folded before pass_stdarg. */ | |
2446 | result = optimize_stdarg_builtin (stmt); | |
2447 | if (result) | |
2448 | break; | |
2449 | /* FALLTHRU */ | |
2450 | ||
2451 | default: | |
2452 | gsi_next (&i); | |
2453 | continue; | |
2454 | } | |
2455 | ||
2456 | if (result == NULL_TREE) | |
2457 | break; | |
2458 | ||
2459 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2460 | { | |
2461 | fprintf (dump_file, "Simplified\n "); | |
2462 | print_gimple_stmt (dump_file, stmt, 0, dump_flags); | |
2463 | } | |
2464 | ||
2465 | old_stmt = stmt; | |
2466 | if (!update_call_from_tree (&i, result)) | |
2467 | { | |
2468 | gimplify_and_update_call_from_tree (&i, result); | |
2469 | todoflags |= TODO_update_address_taken; | |
2470 | } | |
2471 | ||
2472 | stmt = gsi_stmt (i); | |
2473 | update_stmt (stmt); | |
2474 | ||
2475 | if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt) | |
2476 | && gimple_purge_dead_eh_edges (bb)) | |
2477 | cfg_changed = true; | |
2478 | ||
2479 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2480 | { | |
2481 | fprintf (dump_file, "to\n "); | |
2482 | print_gimple_stmt (dump_file, stmt, 0, dump_flags); | |
2483 | fprintf (dump_file, "\n"); | |
2484 | } | |
2485 | ||
2486 | /* Retry the same statement if it changed into another | |
2487 | builtin, there might be new opportunities now. */ | |
2488 | if (gimple_code (stmt) != GIMPLE_CALL) | |
2489 | { | |
2490 | gsi_next (&i); | |
2491 | continue; | |
2492 | } | |
2493 | callee = gimple_call_fndecl (stmt); | |
2494 | if (!callee | |
2495 | || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL | |
2496 | || DECL_FUNCTION_CODE (callee) == fcode) | |
2497 | gsi_next (&i); | |
2498 | } | |
2499 | } | |
2500 | ||
2501 | /* Delete unreachable blocks. */ | |
2502 | if (cfg_changed) | |
2503 | todoflags |= TODO_cleanup_cfg; | |
2504 | ||
2505 | return todoflags; | |
2506 | } | |
2507 | ||
2508 | ||
2509 | struct gimple_opt_pass pass_fold_builtins = | |
2510 | { | |
2511 | { | |
2512 | GIMPLE_PASS, | |
2513 | "fab", /* name */ | |
2514 | OPTGROUP_NONE, /* optinfo_flags */ | |
2515 | NULL, /* gate */ | |
2516 | execute_fold_all_builtins, /* execute */ | |
2517 | NULL, /* sub */ | |
2518 | NULL, /* next */ | |
2519 | 0, /* static_pass_number */ | |
2520 | TV_NONE, /* tv_id */ | |
2521 | PROP_cfg | PROP_ssa, /* properties_required */ | |
2522 | 0, /* properties_provided */ | |
2523 | 0, /* properties_destroyed */ | |
2524 | 0, /* todo_flags_start */ | |
2525 | TODO_verify_ssa | |
2526 | | TODO_update_ssa /* todo_flags_finish */ | |
2527 | } | |
2528 | }; |