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4ee9c684 | 1 | /* Conditional constant propagation pass for the GNU compiler. |
535664e3 | 2 | Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006 |
000657b5 | 3 | Free Software Foundation, Inc. |
4ee9c684 | 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 2, 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 COPYING. If not, write to the Free | |
67ce556b | 21 | Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA |
22 | 02110-1301, USA. */ | |
4ee9c684 | 23 | |
88dbf20f | 24 | /* Conditional constant propagation (CCP) is based on the SSA |
25 | propagation engine (tree-ssa-propagate.c). Constant assignments of | |
26 | the form VAR = CST are propagated from the assignments into uses of | |
27 | VAR, which in turn may generate new constants. The simulation uses | |
28 | a four level lattice to keep track of constant values associated | |
29 | with SSA names. Given an SSA name V_i, it may take one of the | |
30 | following values: | |
31 | ||
bfa30570 | 32 | UNINITIALIZED -> the initial state of the value. This value |
33 | is replaced with a correct initial value | |
34 | the first time the value is used, so the | |
35 | rest of the pass does not need to care about | |
36 | it. Using this value simplifies initialization | |
37 | of the pass, and prevents us from needlessly | |
38 | scanning statements that are never reached. | |
88dbf20f | 39 | |
40 | UNDEFINED -> V_i is a local variable whose definition | |
41 | has not been processed yet. Therefore we | |
42 | don't yet know if its value is a constant | |
43 | or not. | |
44 | ||
45 | CONSTANT -> V_i has been found to hold a constant | |
46 | value C. | |
47 | ||
48 | VARYING -> V_i cannot take a constant value, or if it | |
49 | does, it is not possible to determine it | |
50 | at compile time. | |
51 | ||
52 | The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node: | |
53 | ||
54 | 1- In ccp_visit_stmt, we are interested in assignments whose RHS | |
55 | evaluates into a constant and conditional jumps whose predicate | |
56 | evaluates into a boolean true or false. When an assignment of | |
57 | the form V_i = CONST is found, V_i's lattice value is set to | |
58 | CONSTANT and CONST is associated with it. This causes the | |
59 | propagation engine to add all the SSA edges coming out the | |
60 | assignment into the worklists, so that statements that use V_i | |
61 | can be visited. | |
62 | ||
63 | If the statement is a conditional with a constant predicate, we | |
64 | mark the outgoing edges as executable or not executable | |
65 | depending on the predicate's value. This is then used when | |
66 | visiting PHI nodes to know when a PHI argument can be ignored. | |
67 | ||
68 | ||
69 | 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the | |
70 | same constant C, then the LHS of the PHI is set to C. This | |
71 | evaluation is known as the "meet operation". Since one of the | |
72 | goals of this evaluation is to optimistically return constant | |
73 | values as often as possible, it uses two main short cuts: | |
74 | ||
75 | - If an argument is flowing in through a non-executable edge, it | |
76 | is ignored. This is useful in cases like this: | |
77 | ||
78 | if (PRED) | |
79 | a_9 = 3; | |
80 | else | |
81 | a_10 = 100; | |
82 | a_11 = PHI (a_9, a_10) | |
83 | ||
84 | If PRED is known to always evaluate to false, then we can | |
85 | assume that a_11 will always take its value from a_10, meaning | |
86 | that instead of consider it VARYING (a_9 and a_10 have | |
87 | different values), we can consider it CONSTANT 100. | |
88 | ||
89 | - If an argument has an UNDEFINED value, then it does not affect | |
90 | the outcome of the meet operation. If a variable V_i has an | |
91 | UNDEFINED value, it means that either its defining statement | |
92 | hasn't been visited yet or V_i has no defining statement, in | |
93 | which case the original symbol 'V' is being used | |
94 | uninitialized. Since 'V' is a local variable, the compiler | |
95 | may assume any initial value for it. | |
96 | ||
97 | ||
98 | After propagation, every variable V_i that ends up with a lattice | |
99 | value of CONSTANT will have the associated constant value in the | |
100 | array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for | |
101 | final substitution and folding. | |
102 | ||
103 | ||
104 | Constant propagation in stores and loads (STORE-CCP) | |
105 | ---------------------------------------------------- | |
106 | ||
107 | While CCP has all the logic to propagate constants in GIMPLE | |
108 | registers, it is missing the ability to associate constants with | |
109 | stores and loads (i.e., pointer dereferences, structures and | |
110 | global/aliased variables). We don't keep loads and stores in | |
111 | SSA, but we do build a factored use-def web for them (in the | |
112 | virtual operands). | |
113 | ||
114 | For instance, consider the following code fragment: | |
115 | ||
116 | struct A a; | |
117 | const int B = 42; | |
118 | ||
119 | void foo (int i) | |
120 | { | |
121 | if (i > 10) | |
122 | a.a = 42; | |
123 | else | |
124 | { | |
125 | a.b = 21; | |
126 | a.a = a.b + 21; | |
127 | } | |
128 | ||
129 | if (a.a != B) | |
130 | never_executed (); | |
131 | } | |
132 | ||
133 | We should be able to deduce that the predicate 'a.a != B' is always | |
134 | false. To achieve this, we associate constant values to the SSA | |
135 | names in the V_MAY_DEF and V_MUST_DEF operands for each store. | |
136 | Additionally, since we also glob partial loads/stores with the base | |
137 | symbol, we also keep track of the memory reference where the | |
138 | constant value was stored (in the MEM_REF field of PROP_VALUE_T). | |
139 | For instance, | |
140 | ||
141 | # a_5 = V_MAY_DEF <a_4> | |
142 | a.a = 2; | |
143 | ||
144 | # VUSE <a_5> | |
145 | x_3 = a.b; | |
146 | ||
147 | In the example above, CCP will associate value '2' with 'a_5', but | |
148 | it would be wrong to replace the load from 'a.b' with '2', because | |
149 | '2' had been stored into a.a. | |
150 | ||
bfa30570 | 151 | Note that the initial value of virtual operands is VARYING, not |
152 | UNDEFINED. Consider, for instance global variables: | |
88dbf20f | 153 | |
154 | int A; | |
155 | ||
156 | foo (int i) | |
157 | { | |
158 | if (i_3 > 10) | |
159 | A_4 = 3; | |
160 | # A_5 = PHI (A_4, A_2); | |
161 | ||
162 | # VUSE <A_5> | |
163 | A.0_6 = A; | |
164 | ||
165 | return A.0_6; | |
166 | } | |
167 | ||
168 | The value of A_2 cannot be assumed to be UNDEFINED, as it may have | |
169 | been defined outside of foo. If we were to assume it UNDEFINED, we | |
bfa30570 | 170 | would erroneously optimize the above into 'return 3;'. |
88dbf20f | 171 | |
172 | Though STORE-CCP is not too expensive, it does have to do more work | |
173 | than regular CCP, so it is only enabled at -O2. Both regular CCP | |
174 | and STORE-CCP use the exact same algorithm. The only distinction | |
175 | is that when doing STORE-CCP, the boolean variable DO_STORE_CCP is | |
176 | set to true. This affects the evaluation of statements and PHI | |
177 | nodes. | |
4ee9c684 | 178 | |
179 | References: | |
180 | ||
181 | Constant propagation with conditional branches, | |
182 | Wegman and Zadeck, ACM TOPLAS 13(2):181-210. | |
183 | ||
184 | Building an Optimizing Compiler, | |
185 | Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9. | |
186 | ||
187 | Advanced Compiler Design and Implementation, | |
188 | Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */ | |
189 | ||
190 | #include "config.h" | |
191 | #include "system.h" | |
192 | #include "coretypes.h" | |
193 | #include "tm.h" | |
4ee9c684 | 194 | #include "tree.h" |
41511585 | 195 | #include "flags.h" |
4ee9c684 | 196 | #include "rtl.h" |
197 | #include "tm_p.h" | |
41511585 | 198 | #include "ggc.h" |
4ee9c684 | 199 | #include "basic-block.h" |
41511585 | 200 | #include "output.h" |
41511585 | 201 | #include "expr.h" |
202 | #include "function.h" | |
4ee9c684 | 203 | #include "diagnostic.h" |
41511585 | 204 | #include "timevar.h" |
4ee9c684 | 205 | #include "tree-dump.h" |
41511585 | 206 | #include "tree-flow.h" |
4ee9c684 | 207 | #include "tree-pass.h" |
41511585 | 208 | #include "tree-ssa-propagate.h" |
209 | #include "langhooks.h" | |
8782adcf | 210 | #include "target.h" |
4ee9c684 | 211 | |
212 | ||
213 | /* Possible lattice values. */ | |
214 | typedef enum | |
215 | { | |
bfa30570 | 216 | UNINITIALIZED, |
4ee9c684 | 217 | UNDEFINED, |
218 | CONSTANT, | |
219 | VARYING | |
88dbf20f | 220 | } ccp_lattice_t; |
4ee9c684 | 221 | |
88dbf20f | 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 V_MAY_DEF or V_MUST_DEF), CONST_VAL[I].MEM_REF will | |
226 | contain the actual memory reference used to store (i.e., the LHS of | |
227 | the assignment doing the store). */ | |
20140406 | 228 | static prop_value_t *const_val; |
4ee9c684 | 229 | |
88dbf20f | 230 | /* True if we are also propagating constants in stores and loads. */ |
231 | static bool do_store_ccp; | |
4ee9c684 | 232 | |
88dbf20f | 233 | /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */ |
01406fc0 | 234 | |
235 | static void | |
88dbf20f | 236 | dump_lattice_value (FILE *outf, const char *prefix, prop_value_t val) |
01406fc0 | 237 | { |
41511585 | 238 | switch (val.lattice_val) |
01406fc0 | 239 | { |
88dbf20f | 240 | case UNINITIALIZED: |
241 | fprintf (outf, "%sUNINITIALIZED", prefix); | |
242 | break; | |
41511585 | 243 | case UNDEFINED: |
244 | fprintf (outf, "%sUNDEFINED", prefix); | |
245 | break; | |
246 | case VARYING: | |
247 | fprintf (outf, "%sVARYING", prefix); | |
248 | break; | |
41511585 | 249 | case CONSTANT: |
250 | fprintf (outf, "%sCONSTANT ", prefix); | |
88dbf20f | 251 | print_generic_expr (outf, val.value, dump_flags); |
41511585 | 252 | break; |
253 | default: | |
8c0963c4 | 254 | gcc_unreachable (); |
41511585 | 255 | } |
01406fc0 | 256 | } |
4ee9c684 | 257 | |
4ee9c684 | 258 | |
88dbf20f | 259 | /* Print lattice value VAL to stderr. */ |
260 | ||
261 | void debug_lattice_value (prop_value_t val); | |
262 | ||
263 | void | |
264 | debug_lattice_value (prop_value_t val) | |
265 | { | |
266 | dump_lattice_value (stderr, "", val); | |
267 | fprintf (stderr, "\n"); | |
268 | } | |
4ee9c684 | 269 | |
4ee9c684 | 270 | |
d03bd588 | 271 | /* The regular is_gimple_min_invariant does a shallow test of the object. |
272 | It assumes that full gimplification has happened, or will happen on the | |
273 | object. For a value coming from DECL_INITIAL, this is not true, so we | |
191ec5a2 | 274 | have to be more strict ourselves. */ |
d03bd588 | 275 | |
276 | static bool | |
277 | ccp_decl_initial_min_invariant (tree t) | |
278 | { | |
279 | if (!is_gimple_min_invariant (t)) | |
280 | return false; | |
281 | if (TREE_CODE (t) == ADDR_EXPR) | |
282 | { | |
283 | /* Inline and unroll is_gimple_addressable. */ | |
284 | while (1) | |
285 | { | |
286 | t = TREE_OPERAND (t, 0); | |
287 | if (is_gimple_id (t)) | |
288 | return true; | |
289 | if (!handled_component_p (t)) | |
290 | return false; | |
291 | } | |
292 | } | |
293 | return true; | |
294 | } | |
295 | ||
aecfc21d | 296 | /* If SYM is a constant variable with known value, return the value. |
297 | NULL_TREE is returned otherwise. */ | |
298 | ||
299 | static tree | |
300 | get_symbol_constant_value (tree sym) | |
301 | { | |
302 | if (TREE_STATIC (sym) | |
303 | && TREE_READONLY (sym) | |
304 | && !MTAG_P (sym)) | |
305 | { | |
306 | tree val = DECL_INITIAL (sym); | |
307 | if (val | |
308 | && ccp_decl_initial_min_invariant (val)) | |
309 | return val; | |
310 | } | |
311 | ||
312 | return NULL_TREE; | |
313 | } | |
d03bd588 | 314 | |
88dbf20f | 315 | /* Compute a default value for variable VAR and store it in the |
316 | CONST_VAL array. The following rules are used to get default | |
317 | values: | |
01406fc0 | 318 | |
88dbf20f | 319 | 1- Global and static variables that are declared constant are |
320 | considered CONSTANT. | |
321 | ||
322 | 2- Any other value is considered UNDEFINED. This is useful when | |
41511585 | 323 | considering PHI nodes. PHI arguments that are undefined do not |
324 | change the constant value of the PHI node, which allows for more | |
88dbf20f | 325 | constants to be propagated. |
4ee9c684 | 326 | |
88dbf20f | 327 | 3- If SSA_NAME_VALUE is set and it is a constant, its value is |
328 | used. | |
4ee9c684 | 329 | |
88dbf20f | 330 | 4- Variables defined by statements other than assignments and PHI |
331 | nodes are considered VARYING. | |
4ee9c684 | 332 | |
bfa30570 | 333 | 5- Initial values of variables that are not GIMPLE registers are |
334 | considered VARYING. */ | |
4ee9c684 | 335 | |
88dbf20f | 336 | static prop_value_t |
337 | get_default_value (tree var) | |
338 | { | |
339 | tree sym = SSA_NAME_VAR (var); | |
340 | prop_value_t val = { UNINITIALIZED, NULL_TREE, NULL_TREE }; | |
aecfc21d | 341 | tree cst_val; |
bfa30570 | 342 | |
88dbf20f | 343 | if (!do_store_ccp && !is_gimple_reg (var)) |
4ee9c684 | 344 | { |
88dbf20f | 345 | /* Short circuit for regular CCP. We are not interested in any |
346 | non-register when DO_STORE_CCP is false. */ | |
41511585 | 347 | val.lattice_val = VARYING; |
4ee9c684 | 348 | } |
88dbf20f | 349 | else if (SSA_NAME_VALUE (var) |
350 | && is_gimple_min_invariant (SSA_NAME_VALUE (var))) | |
41511585 | 351 | { |
88dbf20f | 352 | val.lattice_val = CONSTANT; |
353 | val.value = SSA_NAME_VALUE (var); | |
41511585 | 354 | } |
aecfc21d | 355 | else if ((cst_val = get_symbol_constant_value (sym)) != NULL_TREE) |
41511585 | 356 | { |
88dbf20f | 357 | /* Globals and static variables declared 'const' take their |
358 | initial value. */ | |
359 | val.lattice_val = CONSTANT; | |
aecfc21d | 360 | val.value = cst_val; |
88dbf20f | 361 | val.mem_ref = sym; |
41511585 | 362 | } |
363 | else | |
364 | { | |
41511585 | 365 | tree stmt = SSA_NAME_DEF_STMT (var); |
4ee9c684 | 366 | |
88dbf20f | 367 | if (IS_EMPTY_STMT (stmt)) |
368 | { | |
369 | /* Variables defined by an empty statement are those used | |
370 | before being initialized. If VAR is a local variable, we | |
bfa30570 | 371 | can assume initially that it is UNDEFINED, otherwise we must |
372 | consider it VARYING. */ | |
88dbf20f | 373 | if (is_gimple_reg (sym) && TREE_CODE (sym) != PARM_DECL) |
374 | val.lattice_val = UNDEFINED; | |
88dbf20f | 375 | else |
41511585 | 376 | val.lattice_val = VARYING; |
377 | } | |
35cc02b5 | 378 | else if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT |
88dbf20f | 379 | || TREE_CODE (stmt) == PHI_NODE) |
380 | { | |
381 | /* Any other variable defined by an assignment or a PHI node | |
bfa30570 | 382 | is considered UNDEFINED. */ |
383 | val.lattice_val = UNDEFINED; | |
88dbf20f | 384 | } |
385 | else | |
386 | { | |
387 | /* Otherwise, VAR will never take on a constant value. */ | |
388 | val.lattice_val = VARYING; | |
389 | } | |
41511585 | 390 | } |
4ee9c684 | 391 | |
41511585 | 392 | return val; |
393 | } | |
4ee9c684 | 394 | |
4ee9c684 | 395 | |
bfa30570 | 396 | /* Get the constant value associated with variable VAR. */ |
4ee9c684 | 397 | |
bfa30570 | 398 | static inline prop_value_t * |
399 | get_value (tree var) | |
88dbf20f | 400 | { |
401 | prop_value_t *val = &const_val[SSA_NAME_VERSION (var)]; | |
bfa30570 | 402 | |
403 | if (val->lattice_val == UNINITIALIZED) | |
4ee9c684 | 404 | *val = get_default_value (var); |
405 | ||
406 | return val; | |
407 | } | |
408 | ||
bfa30570 | 409 | /* Sets the value associated with VAR to VARYING. */ |
410 | ||
411 | static inline void | |
412 | set_value_varying (tree var) | |
413 | { | |
414 | prop_value_t *val = &const_val[SSA_NAME_VERSION (var)]; | |
415 | ||
416 | val->lattice_val = VARYING; | |
417 | val->value = NULL_TREE; | |
418 | val->mem_ref = NULL_TREE; | |
419 | } | |
4ee9c684 | 420 | |
b31eb493 | 421 | /* For float types, modify the value of VAL to make ccp work correctly |
422 | for non-standard values (-0, NaN): | |
423 | ||
424 | If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0. | |
425 | If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED. | |
426 | This is to fix the following problem (see PR 29921): Suppose we have | |
427 | ||
428 | x = 0.0 * y | |
429 | ||
430 | and we set value of y to NaN. This causes value of x to be set to NaN. | |
431 | When we later determine that y is in fact VARYING, fold uses the fact | |
432 | that HONOR_NANS is false, and we try to change the value of x to 0, | |
433 | causing an ICE. With HONOR_NANS being false, the real appearance of | |
434 | NaN would cause undefined behavior, though, so claiming that y (and x) | |
435 | are UNDEFINED initially is correct. */ | |
436 | ||
437 | static void | |
438 | canonicalize_float_value (prop_value_t *val) | |
439 | { | |
440 | enum machine_mode mode; | |
441 | tree type; | |
442 | REAL_VALUE_TYPE d; | |
443 | ||
444 | if (val->lattice_val != CONSTANT | |
445 | || TREE_CODE (val->value) != REAL_CST) | |
446 | return; | |
447 | ||
448 | d = TREE_REAL_CST (val->value); | |
449 | type = TREE_TYPE (val->value); | |
450 | mode = TYPE_MODE (type); | |
451 | ||
452 | if (!HONOR_SIGNED_ZEROS (mode) | |
453 | && REAL_VALUE_MINUS_ZERO (d)) | |
454 | { | |
455 | val->value = build_real (type, dconst0); | |
456 | return; | |
457 | } | |
458 | ||
459 | if (!HONOR_NANS (mode) | |
460 | && REAL_VALUE_ISNAN (d)) | |
461 | { | |
462 | val->lattice_val = UNDEFINED; | |
463 | val->value = NULL; | |
464 | val->mem_ref = NULL; | |
465 | return; | |
466 | } | |
467 | } | |
468 | ||
88dbf20f | 469 | /* Set the value for variable VAR to NEW_VAL. Return true if the new |
470 | value is different from VAR's previous value. */ | |
4ee9c684 | 471 | |
41511585 | 472 | static bool |
88dbf20f | 473 | set_lattice_value (tree var, prop_value_t new_val) |
4ee9c684 | 474 | { |
bfa30570 | 475 | prop_value_t *old_val = get_value (var); |
88dbf20f | 476 | |
b31eb493 | 477 | canonicalize_float_value (&new_val); |
478 | ||
88dbf20f | 479 | /* Lattice transitions must always be monotonically increasing in |
bfa30570 | 480 | value. If *OLD_VAL and NEW_VAL are the same, return false to |
481 | inform the caller that this was a non-transition. */ | |
482 | ||
aecfc21d | 483 | gcc_assert (old_val->lattice_val < new_val.lattice_val |
88dbf20f | 484 | || (old_val->lattice_val == new_val.lattice_val |
aecfc21d | 485 | && ((!old_val->value && !new_val.value) |
486 | || operand_equal_p (old_val->value, new_val.value, 0)) | |
bfa30570 | 487 | && old_val->mem_ref == new_val.mem_ref)); |
88dbf20f | 488 | |
489 | if (old_val->lattice_val != new_val.lattice_val) | |
4ee9c684 | 490 | { |
41511585 | 491 | if (dump_file && (dump_flags & TDF_DETAILS)) |
492 | { | |
88dbf20f | 493 | dump_lattice_value (dump_file, "Lattice value changed to ", new_val); |
bfa30570 | 494 | fprintf (dump_file, ". Adding SSA edges to worklist.\n"); |
41511585 | 495 | } |
496 | ||
88dbf20f | 497 | *old_val = new_val; |
498 | ||
bfa30570 | 499 | gcc_assert (new_val.lattice_val != UNDEFINED); |
500 | return true; | |
4ee9c684 | 501 | } |
41511585 | 502 | |
503 | return false; | |
4ee9c684 | 504 | } |
505 | ||
506 | ||
88dbf20f | 507 | /* Return the likely CCP lattice value for STMT. |
4ee9c684 | 508 | |
41511585 | 509 | If STMT has no operands, then return CONSTANT. |
4ee9c684 | 510 | |
41511585 | 511 | Else if any operands of STMT are undefined, then return UNDEFINED. |
4ee9c684 | 512 | |
41511585 | 513 | Else if any operands of STMT are constants, then return CONSTANT. |
4ee9c684 | 514 | |
41511585 | 515 | Else return VARYING. */ |
4ee9c684 | 516 | |
88dbf20f | 517 | static ccp_lattice_t |
41511585 | 518 | likely_value (tree stmt) |
519 | { | |
bfa30570 | 520 | bool has_constant_operand; |
41511585 | 521 | stmt_ann_t ann; |
522 | tree use; | |
523 | ssa_op_iter iter; | |
4ee9c684 | 524 | |
41511585 | 525 | ann = stmt_ann (stmt); |
88dbf20f | 526 | |
527 | /* If the statement has volatile operands, it won't fold to a | |
528 | constant value. */ | |
529 | if (ann->has_volatile_ops) | |
530 | return VARYING; | |
531 | ||
532 | /* If we are not doing store-ccp, statements with loads | |
533 | and/or stores will never fold into a constant. */ | |
534 | if (!do_store_ccp | |
9d637cc5 | 535 | && !ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)) |
41511585 | 536 | return VARYING; |
4ee9c684 | 537 | |
88dbf20f | 538 | |
539 | /* A CALL_EXPR is assumed to be varying. NOTE: This may be overly | |
540 | conservative, in the presence of const and pure calls. */ | |
41511585 | 541 | if (get_call_expr_in (stmt) != NULL_TREE) |
542 | return VARYING; | |
4ee9c684 | 543 | |
88dbf20f | 544 | /* Anything other than assignments and conditional jumps are not |
545 | interesting for CCP. */ | |
35cc02b5 | 546 | if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT |
bfa30570 | 547 | && !(TREE_CODE (stmt) == RETURN_EXPR && get_rhs (stmt) != NULL_TREE) |
88dbf20f | 548 | && TREE_CODE (stmt) != COND_EXPR |
549 | && TREE_CODE (stmt) != SWITCH_EXPR) | |
550 | return VARYING; | |
551 | ||
b765fa12 | 552 | if (is_gimple_min_invariant (get_rhs (stmt))) |
553 | return CONSTANT; | |
554 | ||
bfa30570 | 555 | has_constant_operand = false; |
556 | FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE | SSA_OP_VUSE) | |
41511585 | 557 | { |
bfa30570 | 558 | prop_value_t *val = get_value (use); |
41511585 | 559 | |
bfa30570 | 560 | if (val->lattice_val == UNDEFINED) |
561 | return UNDEFINED; | |
88dbf20f | 562 | |
41511585 | 563 | if (val->lattice_val == CONSTANT) |
bfa30570 | 564 | has_constant_operand = true; |
4ee9c684 | 565 | } |
41511585 | 566 | |
bfa30570 | 567 | if (has_constant_operand |
568 | /* We do not consider virtual operands here -- load from read-only | |
569 | memory may have only VARYING virtual operands, but still be | |
570 | constant. */ | |
571 | || ZERO_SSA_OPERANDS (stmt, SSA_OP_USE)) | |
88dbf20f | 572 | return CONSTANT; |
573 | ||
bfa30570 | 574 | return VARYING; |
4ee9c684 | 575 | } |
576 | ||
bfa30570 | 577 | /* Returns true if STMT cannot be constant. */ |
578 | ||
579 | static bool | |
580 | surely_varying_stmt_p (tree stmt) | |
581 | { | |
582 | /* If the statement has operands that we cannot handle, it cannot be | |
583 | constant. */ | |
584 | if (stmt_ann (stmt)->has_volatile_ops) | |
585 | return true; | |
586 | ||
587 | if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)) | |
588 | { | |
589 | if (!do_store_ccp) | |
590 | return true; | |
591 | ||
592 | /* We can only handle simple loads and stores. */ | |
593 | if (!stmt_makes_single_load (stmt) | |
594 | && !stmt_makes_single_store (stmt)) | |
595 | return true; | |
596 | } | |
597 | ||
598 | /* If it contains a call, it is varying. */ | |
599 | if (get_call_expr_in (stmt) != NULL_TREE) | |
600 | return true; | |
601 | ||
602 | /* Anything other than assignments and conditional jumps are not | |
603 | interesting for CCP. */ | |
35cc02b5 | 604 | if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT |
bfa30570 | 605 | && !(TREE_CODE (stmt) == RETURN_EXPR && get_rhs (stmt) != NULL_TREE) |
606 | && TREE_CODE (stmt) != COND_EXPR | |
607 | && TREE_CODE (stmt) != SWITCH_EXPR) | |
608 | return true; | |
609 | ||
610 | return false; | |
611 | } | |
4ee9c684 | 612 | |
41511585 | 613 | /* Initialize local data structures for CCP. */ |
4ee9c684 | 614 | |
615 | static void | |
41511585 | 616 | ccp_initialize (void) |
4ee9c684 | 617 | { |
41511585 | 618 | basic_block bb; |
4ee9c684 | 619 | |
43959b95 | 620 | const_val = XCNEWVEC (prop_value_t, num_ssa_names); |
4ee9c684 | 621 | |
41511585 | 622 | /* Initialize simulation flags for PHI nodes and statements. */ |
623 | FOR_EACH_BB (bb) | |
4ee9c684 | 624 | { |
41511585 | 625 | block_stmt_iterator i; |
4ee9c684 | 626 | |
41511585 | 627 | for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) |
628 | { | |
41511585 | 629 | tree stmt = bsi_stmt (i); |
bfa30570 | 630 | bool is_varying = surely_varying_stmt_p (stmt); |
4ee9c684 | 631 | |
bfa30570 | 632 | if (is_varying) |
41511585 | 633 | { |
88dbf20f | 634 | tree def; |
635 | ssa_op_iter iter; | |
636 | ||
637 | /* If the statement will not produce a constant, mark | |
638 | all its outputs VARYING. */ | |
639 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) | |
bfa30570 | 640 | { |
641 | if (is_varying) | |
642 | set_value_varying (def); | |
643 | } | |
41511585 | 644 | } |
645 | ||
41511585 | 646 | DONT_SIMULATE_AGAIN (stmt) = is_varying; |
647 | } | |
4ee9c684 | 648 | } |
649 | ||
bfa30570 | 650 | /* Now process PHI nodes. We never set DONT_SIMULATE_AGAIN on phi node, |
651 | since we do not know which edges are executable yet, except for | |
652 | phi nodes for virtual operands when we do not do store ccp. */ | |
41511585 | 653 | FOR_EACH_BB (bb) |
4ee9c684 | 654 | { |
88dbf20f | 655 | tree phi; |
41511585 | 656 | |
657 | for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) | |
658 | { | |
bfa30570 | 659 | if (!do_store_ccp && !is_gimple_reg (PHI_RESULT (phi))) |
660 | DONT_SIMULATE_AGAIN (phi) = true; | |
661 | else | |
662 | DONT_SIMULATE_AGAIN (phi) = false; | |
41511585 | 663 | } |
4ee9c684 | 664 | } |
41511585 | 665 | } |
4ee9c684 | 666 | |
4ee9c684 | 667 | |
88dbf20f | 668 | /* Do final substitution of propagated values, cleanup the flowgraph and |
669 | free allocated storage. */ | |
4ee9c684 | 670 | |
88dbf20f | 671 | static void |
672 | ccp_finalize (void) | |
4ee9c684 | 673 | { |
88dbf20f | 674 | /* Perform substitutions based on the known constant values. */ |
eea12c72 | 675 | substitute_and_fold (const_val, false); |
4ee9c684 | 676 | |
88dbf20f | 677 | free (const_val); |
4ee9c684 | 678 | } |
679 | ||
680 | ||
88dbf20f | 681 | /* Compute the meet operator between *VAL1 and *VAL2. Store the result |
682 | in VAL1. | |
683 | ||
684 | any M UNDEFINED = any | |
88dbf20f | 685 | any M VARYING = VARYING |
686 | Ci M Cj = Ci if (i == j) | |
687 | Ci M Cj = VARYING if (i != j) | |
bfa30570 | 688 | */ |
4ee9c684 | 689 | |
690 | static void | |
88dbf20f | 691 | ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2) |
4ee9c684 | 692 | { |
88dbf20f | 693 | if (val1->lattice_val == UNDEFINED) |
4ee9c684 | 694 | { |
88dbf20f | 695 | /* UNDEFINED M any = any */ |
696 | *val1 = *val2; | |
41511585 | 697 | } |
88dbf20f | 698 | else if (val2->lattice_val == UNDEFINED) |
92481a4d | 699 | { |
88dbf20f | 700 | /* any M UNDEFINED = any |
701 | Nothing to do. VAL1 already contains the value we want. */ | |
702 | ; | |
92481a4d | 703 | } |
88dbf20f | 704 | else if (val1->lattice_val == VARYING |
705 | || val2->lattice_val == VARYING) | |
41511585 | 706 | { |
88dbf20f | 707 | /* any M VARYING = VARYING. */ |
708 | val1->lattice_val = VARYING; | |
709 | val1->value = NULL_TREE; | |
710 | val1->mem_ref = NULL_TREE; | |
41511585 | 711 | } |
88dbf20f | 712 | else if (val1->lattice_val == CONSTANT |
713 | && val2->lattice_val == CONSTANT | |
714 | && simple_cst_equal (val1->value, val2->value) == 1 | |
715 | && (!do_store_ccp | |
b765fa12 | 716 | || (val1->mem_ref && val2->mem_ref |
717 | && operand_equal_p (val1->mem_ref, val2->mem_ref, 0)))) | |
41511585 | 718 | { |
88dbf20f | 719 | /* Ci M Cj = Ci if (i == j) |
720 | Ci M Cj = VARYING if (i != j) | |
721 | ||
722 | If these two values come from memory stores, make sure that | |
723 | they come from the same memory reference. */ | |
724 | val1->lattice_val = CONSTANT; | |
725 | val1->value = val1->value; | |
726 | val1->mem_ref = val1->mem_ref; | |
41511585 | 727 | } |
728 | else | |
729 | { | |
88dbf20f | 730 | /* Any other combination is VARYING. */ |
731 | val1->lattice_val = VARYING; | |
732 | val1->value = NULL_TREE; | |
733 | val1->mem_ref = NULL_TREE; | |
41511585 | 734 | } |
4ee9c684 | 735 | } |
736 | ||
737 | ||
41511585 | 738 | /* Loop through the PHI_NODE's parameters for BLOCK and compare their |
739 | lattice values to determine PHI_NODE's lattice value. The value of a | |
88dbf20f | 740 | PHI node is determined calling ccp_lattice_meet with all the arguments |
41511585 | 741 | of the PHI node that are incoming via executable edges. */ |
4ee9c684 | 742 | |
41511585 | 743 | static enum ssa_prop_result |
744 | ccp_visit_phi_node (tree phi) | |
4ee9c684 | 745 | { |
41511585 | 746 | int i; |
88dbf20f | 747 | prop_value_t *old_val, new_val; |
4ee9c684 | 748 | |
41511585 | 749 | if (dump_file && (dump_flags & TDF_DETAILS)) |
4ee9c684 | 750 | { |
41511585 | 751 | fprintf (dump_file, "\nVisiting PHI node: "); |
752 | print_generic_expr (dump_file, phi, dump_flags); | |
4ee9c684 | 753 | } |
4ee9c684 | 754 | |
bfa30570 | 755 | old_val = get_value (PHI_RESULT (phi)); |
41511585 | 756 | switch (old_val->lattice_val) |
757 | { | |
758 | case VARYING: | |
88dbf20f | 759 | return SSA_PROP_VARYING; |
4ee9c684 | 760 | |
41511585 | 761 | case CONSTANT: |
762 | new_val = *old_val; | |
763 | break; | |
4ee9c684 | 764 | |
41511585 | 765 | case UNDEFINED: |
41511585 | 766 | new_val.lattice_val = UNDEFINED; |
88dbf20f | 767 | new_val.value = NULL_TREE; |
768 | new_val.mem_ref = NULL_TREE; | |
41511585 | 769 | break; |
4ee9c684 | 770 | |
41511585 | 771 | default: |
8c0963c4 | 772 | gcc_unreachable (); |
41511585 | 773 | } |
4ee9c684 | 774 | |
41511585 | 775 | for (i = 0; i < PHI_NUM_ARGS (phi); i++) |
776 | { | |
88dbf20f | 777 | /* Compute the meet operator over all the PHI arguments flowing |
778 | through executable edges. */ | |
41511585 | 779 | edge e = PHI_ARG_EDGE (phi, i); |
4ee9c684 | 780 | |
41511585 | 781 | if (dump_file && (dump_flags & TDF_DETAILS)) |
782 | { | |
783 | fprintf (dump_file, | |
784 | "\n Argument #%d (%d -> %d %sexecutable)\n", | |
785 | i, e->src->index, e->dest->index, | |
786 | (e->flags & EDGE_EXECUTABLE) ? "" : "not "); | |
787 | } | |
788 | ||
789 | /* If the incoming edge is executable, Compute the meet operator for | |
790 | the existing value of the PHI node and the current PHI argument. */ | |
791 | if (e->flags & EDGE_EXECUTABLE) | |
792 | { | |
88dbf20f | 793 | tree arg = PHI_ARG_DEF (phi, i); |
794 | prop_value_t arg_val; | |
4ee9c684 | 795 | |
88dbf20f | 796 | if (is_gimple_min_invariant (arg)) |
41511585 | 797 | { |
88dbf20f | 798 | arg_val.lattice_val = CONSTANT; |
799 | arg_val.value = arg; | |
800 | arg_val.mem_ref = NULL_TREE; | |
41511585 | 801 | } |
802 | else | |
bfa30570 | 803 | arg_val = *(get_value (arg)); |
4ee9c684 | 804 | |
88dbf20f | 805 | ccp_lattice_meet (&new_val, &arg_val); |
4ee9c684 | 806 | |
41511585 | 807 | if (dump_file && (dump_flags & TDF_DETAILS)) |
808 | { | |
809 | fprintf (dump_file, "\t"); | |
88dbf20f | 810 | print_generic_expr (dump_file, arg, dump_flags); |
811 | dump_lattice_value (dump_file, "\tValue: ", arg_val); | |
41511585 | 812 | fprintf (dump_file, "\n"); |
813 | } | |
4ee9c684 | 814 | |
41511585 | 815 | if (new_val.lattice_val == VARYING) |
816 | break; | |
817 | } | |
818 | } | |
4ee9c684 | 819 | |
820 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
41511585 | 821 | { |
822 | dump_lattice_value (dump_file, "\n PHI node value: ", new_val); | |
823 | fprintf (dump_file, "\n\n"); | |
824 | } | |
825 | ||
bfa30570 | 826 | /* Make the transition to the new value. */ |
41511585 | 827 | if (set_lattice_value (PHI_RESULT (phi), new_val)) |
828 | { | |
829 | if (new_val.lattice_val == VARYING) | |
830 | return SSA_PROP_VARYING; | |
831 | else | |
832 | return SSA_PROP_INTERESTING; | |
833 | } | |
834 | else | |
835 | return SSA_PROP_NOT_INTERESTING; | |
4ee9c684 | 836 | } |
837 | ||
838 | ||
41511585 | 839 | /* CCP specific front-end to the non-destructive constant folding |
840 | routines. | |
4ee9c684 | 841 | |
842 | Attempt to simplify the RHS of STMT knowing that one or more | |
843 | operands are constants. | |
844 | ||
845 | If simplification is possible, return the simplified RHS, | |
846 | otherwise return the original RHS. */ | |
847 | ||
848 | static tree | |
849 | ccp_fold (tree stmt) | |
850 | { | |
851 | tree rhs = get_rhs (stmt); | |
852 | enum tree_code code = TREE_CODE (rhs); | |
ce45a448 | 853 | enum tree_code_class kind = TREE_CODE_CLASS (code); |
4ee9c684 | 854 | tree retval = NULL_TREE; |
855 | ||
4ee9c684 | 856 | if (TREE_CODE (rhs) == SSA_NAME) |
88dbf20f | 857 | { |
858 | /* If the RHS is an SSA_NAME, return its known constant value, | |
859 | if any. */ | |
bfa30570 | 860 | return get_value (rhs)->value; |
88dbf20f | 861 | } |
862 | else if (do_store_ccp && stmt_makes_single_load (stmt)) | |
863 | { | |
864 | /* If the RHS is a memory load, see if the VUSEs associated with | |
865 | it are a valid constant for that memory load. */ | |
866 | prop_value_t *val = get_value_loaded_by (stmt, const_val); | |
5d66655a | 867 | if (val && val->mem_ref) |
868 | { | |
869 | if (operand_equal_p (val->mem_ref, rhs, 0)) | |
870 | return val->value; | |
871 | ||
872 | /* If RHS is extracting REALPART_EXPR or IMAGPART_EXPR of a | |
873 | complex type with a known constant value, return it. */ | |
874 | if ((TREE_CODE (rhs) == REALPART_EXPR | |
875 | || TREE_CODE (rhs) == IMAGPART_EXPR) | |
876 | && operand_equal_p (val->mem_ref, TREE_OPERAND (rhs, 0), 0)) | |
877 | return fold_build1 (TREE_CODE (rhs), TREE_TYPE (rhs), val->value); | |
878 | } | |
879 | return NULL_TREE; | |
88dbf20f | 880 | } |
4ee9c684 | 881 | |
882 | /* Unary operators. Note that we know the single operand must | |
883 | be a constant. So this should almost always return a | |
884 | simplified RHS. */ | |
ce45a448 | 885 | if (kind == tcc_unary) |
4ee9c684 | 886 | { |
887 | /* Handle unary operators which can appear in GIMPLE form. */ | |
888 | tree op0 = TREE_OPERAND (rhs, 0); | |
889 | ||
890 | /* Simplify the operand down to a constant. */ | |
891 | if (TREE_CODE (op0) == SSA_NAME) | |
892 | { | |
bfa30570 | 893 | prop_value_t *val = get_value (op0); |
4ee9c684 | 894 | if (val->lattice_val == CONSTANT) |
bfa30570 | 895 | op0 = get_value (op0)->value; |
4ee9c684 | 896 | } |
897 | ||
ad78532f | 898 | if ((code == NOP_EXPR || code == CONVERT_EXPR) |
899 | && tree_ssa_useless_type_conversion_1 (TREE_TYPE (rhs), | |
900 | TREE_TYPE (op0))) | |
901 | return op0; | |
1675c594 | 902 | return fold_unary (code, TREE_TYPE (rhs), op0); |
4ee9c684 | 903 | } |
904 | ||
905 | /* Binary and comparison operators. We know one or both of the | |
906 | operands are constants. */ | |
ce45a448 | 907 | else if (kind == tcc_binary |
908 | || kind == tcc_comparison | |
4ee9c684 | 909 | || code == TRUTH_AND_EXPR |
910 | || code == TRUTH_OR_EXPR | |
911 | || code == TRUTH_XOR_EXPR) | |
912 | { | |
913 | /* Handle binary and comparison operators that can appear in | |
914 | GIMPLE form. */ | |
915 | tree op0 = TREE_OPERAND (rhs, 0); | |
916 | tree op1 = TREE_OPERAND (rhs, 1); | |
917 | ||
918 | /* Simplify the operands down to constants when appropriate. */ | |
919 | if (TREE_CODE (op0) == SSA_NAME) | |
920 | { | |
bfa30570 | 921 | prop_value_t *val = get_value (op0); |
4ee9c684 | 922 | if (val->lattice_val == CONSTANT) |
88dbf20f | 923 | op0 = val->value; |
4ee9c684 | 924 | } |
925 | ||
926 | if (TREE_CODE (op1) == SSA_NAME) | |
927 | { | |
bfa30570 | 928 | prop_value_t *val = get_value (op1); |
4ee9c684 | 929 | if (val->lattice_val == CONSTANT) |
88dbf20f | 930 | op1 = val->value; |
4ee9c684 | 931 | } |
932 | ||
1675c594 | 933 | return fold_binary (code, TREE_TYPE (rhs), op0, op1); |
4ee9c684 | 934 | } |
935 | ||
936 | /* We may be able to fold away calls to builtin functions if their | |
0bed3869 | 937 | arguments are constants. */ |
4ee9c684 | 938 | else if (code == CALL_EXPR |
939 | && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR | |
940 | && (TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)) | |
941 | == FUNCTION_DECL) | |
942 | && DECL_BUILT_IN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))) | |
943 | { | |
b66731e8 | 944 | if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_USE)) |
4ee9c684 | 945 | { |
b66731e8 | 946 | tree *orig, var; |
4a4d48d5 | 947 | tree fndecl, arglist; |
b66731e8 | 948 | size_t i = 0; |
949 | ssa_op_iter iter; | |
950 | use_operand_p var_p; | |
4ee9c684 | 951 | |
952 | /* Preserve the original values of every operand. */ | |
680a19b9 | 953 | orig = XNEWVEC (tree, NUM_SSA_OPERANDS (stmt, SSA_OP_USE)); |
b66731e8 | 954 | FOR_EACH_SSA_TREE_OPERAND (var, stmt, iter, SSA_OP_USE) |
955 | orig[i++] = var; | |
4ee9c684 | 956 | |
957 | /* Substitute operands with their values and try to fold. */ | |
88dbf20f | 958 | replace_uses_in (stmt, NULL, const_val); |
4a4d48d5 | 959 | fndecl = get_callee_fndecl (rhs); |
960 | arglist = TREE_OPERAND (rhs, 1); | |
961 | retval = fold_builtin (fndecl, arglist, false); | |
4ee9c684 | 962 | |
963 | /* Restore operands to their original form. */ | |
b66731e8 | 964 | i = 0; |
965 | FOR_EACH_SSA_USE_OPERAND (var_p, stmt, iter, SSA_OP_USE) | |
966 | SET_USE (var_p, orig[i++]); | |
4ee9c684 | 967 | free (orig); |
968 | } | |
969 | } | |
970 | else | |
971 | return rhs; | |
972 | ||
973 | /* If we got a simplified form, see if we need to convert its type. */ | |
974 | if (retval) | |
f0613857 | 975 | return fold_convert (TREE_TYPE (rhs), retval); |
4ee9c684 | 976 | |
977 | /* No simplification was possible. */ | |
978 | return rhs; | |
979 | } | |
980 | ||
981 | ||
8782adcf | 982 | /* Return the tree representing the element referenced by T if T is an |
983 | ARRAY_REF or COMPONENT_REF into constant aggregates. Return | |
984 | NULL_TREE otherwise. */ | |
985 | ||
986 | static tree | |
987 | fold_const_aggregate_ref (tree t) | |
988 | { | |
989 | prop_value_t *value; | |
c75b4594 | 990 | tree base, ctor, idx, field; |
991 | unsigned HOST_WIDE_INT cnt; | |
992 | tree cfield, cval; | |
8782adcf | 993 | |
994 | switch (TREE_CODE (t)) | |
995 | { | |
996 | case ARRAY_REF: | |
997 | /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its | |
998 | DECL_INITIAL. If BASE is a nested reference into another | |
999 | ARRAY_REF or COMPONENT_REF, make a recursive call to resolve | |
1000 | the inner reference. */ | |
1001 | base = TREE_OPERAND (t, 0); | |
1002 | switch (TREE_CODE (base)) | |
1003 | { | |
1004 | case VAR_DECL: | |
1005 | if (!TREE_READONLY (base) | |
1006 | || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE | |
1007 | || !targetm.binds_local_p (base)) | |
1008 | return NULL_TREE; | |
1009 | ||
1010 | ctor = DECL_INITIAL (base); | |
1011 | break; | |
1012 | ||
1013 | case ARRAY_REF: | |
1014 | case COMPONENT_REF: | |
1015 | ctor = fold_const_aggregate_ref (base); | |
1016 | break; | |
1017 | ||
1018 | default: | |
1019 | return NULL_TREE; | |
1020 | } | |
1021 | ||
1022 | if (ctor == NULL_TREE | |
4f61cce6 | 1023 | || (TREE_CODE (ctor) != CONSTRUCTOR |
1024 | && TREE_CODE (ctor) != STRING_CST) | |
8782adcf | 1025 | || !TREE_STATIC (ctor)) |
1026 | return NULL_TREE; | |
1027 | ||
1028 | /* Get the index. If we have an SSA_NAME, try to resolve it | |
1029 | with the current lattice value for the SSA_NAME. */ | |
1030 | idx = TREE_OPERAND (t, 1); | |
1031 | switch (TREE_CODE (idx)) | |
1032 | { | |
1033 | case SSA_NAME: | |
bfa30570 | 1034 | if ((value = get_value (idx)) |
8782adcf | 1035 | && value->lattice_val == CONSTANT |
1036 | && TREE_CODE (value->value) == INTEGER_CST) | |
1037 | idx = value->value; | |
1038 | else | |
1039 | return NULL_TREE; | |
1040 | break; | |
1041 | ||
1042 | case INTEGER_CST: | |
1043 | break; | |
1044 | ||
1045 | default: | |
1046 | return NULL_TREE; | |
1047 | } | |
1048 | ||
4f61cce6 | 1049 | /* Fold read from constant string. */ |
1050 | if (TREE_CODE (ctor) == STRING_CST) | |
1051 | { | |
1052 | if ((TYPE_MODE (TREE_TYPE (t)) | |
1053 | == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) | |
1054 | && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) | |
1055 | == MODE_INT) | |
1056 | && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1 | |
1057 | && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0) | |
1058 | return build_int_cst (TREE_TYPE (t), (TREE_STRING_POINTER (ctor) | |
1059 | [TREE_INT_CST_LOW (idx)])); | |
1060 | return NULL_TREE; | |
1061 | } | |
1062 | ||
8782adcf | 1063 | /* Whoo-hoo! I'll fold ya baby. Yeah! */ |
c75b4594 | 1064 | FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval) |
1065 | if (tree_int_cst_equal (cfield, idx)) | |
1066 | return cval; | |
8782adcf | 1067 | break; |
1068 | ||
1069 | case COMPONENT_REF: | |
1070 | /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its | |
1071 | DECL_INITIAL. If BASE is a nested reference into another | |
1072 | ARRAY_REF or COMPONENT_REF, make a recursive call to resolve | |
1073 | the inner reference. */ | |
1074 | base = TREE_OPERAND (t, 0); | |
1075 | switch (TREE_CODE (base)) | |
1076 | { | |
1077 | case VAR_DECL: | |
1078 | if (!TREE_READONLY (base) | |
1079 | || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE | |
1080 | || !targetm.binds_local_p (base)) | |
1081 | return NULL_TREE; | |
1082 | ||
1083 | ctor = DECL_INITIAL (base); | |
1084 | break; | |
1085 | ||
1086 | case ARRAY_REF: | |
1087 | case COMPONENT_REF: | |
1088 | ctor = fold_const_aggregate_ref (base); | |
1089 | break; | |
1090 | ||
1091 | default: | |
1092 | return NULL_TREE; | |
1093 | } | |
1094 | ||
1095 | if (ctor == NULL_TREE | |
1096 | || TREE_CODE (ctor) != CONSTRUCTOR | |
1097 | || !TREE_STATIC (ctor)) | |
1098 | return NULL_TREE; | |
1099 | ||
1100 | field = TREE_OPERAND (t, 1); | |
1101 | ||
c75b4594 | 1102 | FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval) |
1103 | if (cfield == field | |
8782adcf | 1104 | /* FIXME: Handle bit-fields. */ |
c75b4594 | 1105 | && ! DECL_BIT_FIELD (cfield)) |
1106 | return cval; | |
8782adcf | 1107 | break; |
1108 | ||
908cb59d | 1109 | case REALPART_EXPR: |
1110 | case IMAGPART_EXPR: | |
1111 | { | |
1112 | tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0)); | |
1113 | if (c && TREE_CODE (c) == COMPLEX_CST) | |
1114 | return fold_build1 (TREE_CODE (t), TREE_TYPE (t), c); | |
1115 | break; | |
1116 | } | |
1117 | ||
8782adcf | 1118 | default: |
1119 | break; | |
1120 | } | |
1121 | ||
1122 | return NULL_TREE; | |
1123 | } | |
1124 | ||
4ee9c684 | 1125 | /* Evaluate statement STMT. */ |
1126 | ||
88dbf20f | 1127 | static prop_value_t |
4ee9c684 | 1128 | evaluate_stmt (tree stmt) |
1129 | { | |
88dbf20f | 1130 | prop_value_t val; |
4f61cce6 | 1131 | tree simplified = NULL_TREE; |
88dbf20f | 1132 | ccp_lattice_t likelyvalue = likely_value (stmt); |
1133 | ||
1134 | val.mem_ref = NULL_TREE; | |
4ee9c684 | 1135 | |
1136 | /* If the statement is likely to have a CONSTANT result, then try | |
1137 | to fold the statement to determine the constant value. */ | |
1138 | if (likelyvalue == CONSTANT) | |
1139 | simplified = ccp_fold (stmt); | |
1140 | /* If the statement is likely to have a VARYING result, then do not | |
1141 | bother folding the statement. */ | |
4f61cce6 | 1142 | if (likelyvalue == VARYING) |
4ee9c684 | 1143 | simplified = get_rhs (stmt); |
8782adcf | 1144 | /* If the statement is an ARRAY_REF or COMPONENT_REF into constant |
1145 | aggregates, extract the referenced constant. Otherwise the | |
1146 | statement is likely to have an UNDEFINED value, and there will be | |
1147 | nothing to do. Note that fold_const_aggregate_ref returns | |
1148 | NULL_TREE if the first case does not match. */ | |
4f61cce6 | 1149 | else if (!simplified) |
8782adcf | 1150 | simplified = fold_const_aggregate_ref (get_rhs (stmt)); |
4ee9c684 | 1151 | |
1152 | if (simplified && is_gimple_min_invariant (simplified)) | |
1153 | { | |
1154 | /* The statement produced a constant value. */ | |
1155 | val.lattice_val = CONSTANT; | |
88dbf20f | 1156 | val.value = simplified; |
4ee9c684 | 1157 | } |
1158 | else | |
1159 | { | |
1160 | /* The statement produced a nonconstant value. If the statement | |
88dbf20f | 1161 | had UNDEFINED operands, then the result of the statement |
1162 | should be UNDEFINED. Otherwise, the statement is VARYING. */ | |
bfa30570 | 1163 | if (likelyvalue == UNDEFINED) |
b765fa12 | 1164 | val.lattice_val = likelyvalue; |
1165 | else | |
1166 | val.lattice_val = VARYING; | |
1167 | ||
88dbf20f | 1168 | val.value = NULL_TREE; |
4ee9c684 | 1169 | } |
41511585 | 1170 | |
1171 | return val; | |
4ee9c684 | 1172 | } |
1173 | ||
1174 | ||
41511585 | 1175 | /* Visit the assignment statement STMT. Set the value of its LHS to the |
88dbf20f | 1176 | value computed by the RHS and store LHS in *OUTPUT_P. If STMT |
1177 | creates virtual definitions, set the value of each new name to that | |
1178 | of the RHS (if we can derive a constant out of the RHS). */ | |
4ee9c684 | 1179 | |
41511585 | 1180 | static enum ssa_prop_result |
1181 | visit_assignment (tree stmt, tree *output_p) | |
4ee9c684 | 1182 | { |
88dbf20f | 1183 | prop_value_t val; |
41511585 | 1184 | tree lhs, rhs; |
88dbf20f | 1185 | enum ssa_prop_result retval; |
4ee9c684 | 1186 | |
35cc02b5 | 1187 | lhs = GIMPLE_STMT_OPERAND (stmt, 0); |
1188 | rhs = GIMPLE_STMT_OPERAND (stmt, 1); | |
4ee9c684 | 1189 | |
41511585 | 1190 | if (TREE_CODE (rhs) == SSA_NAME) |
1191 | { | |
1192 | /* For a simple copy operation, we copy the lattice values. */ | |
bfa30570 | 1193 | prop_value_t *nval = get_value (rhs); |
41511585 | 1194 | val = *nval; |
1195 | } | |
88dbf20f | 1196 | else if (do_store_ccp && stmt_makes_single_load (stmt)) |
41511585 | 1197 | { |
88dbf20f | 1198 | /* Same as above, but the RHS is not a gimple register and yet |
bfa30570 | 1199 | has a known VUSE. If STMT is loading from the same memory |
88dbf20f | 1200 | location that created the SSA_NAMEs for the virtual operands, |
1201 | we can propagate the value on the RHS. */ | |
1202 | prop_value_t *nval = get_value_loaded_by (stmt, const_val); | |
1203 | ||
bfa30570 | 1204 | if (nval |
1205 | && nval->mem_ref | |
b765fa12 | 1206 | && operand_equal_p (nval->mem_ref, rhs, 0)) |
88dbf20f | 1207 | val = *nval; |
1208 | else | |
1209 | val = evaluate_stmt (stmt); | |
41511585 | 1210 | } |
1211 | else | |
a065a588 | 1212 | /* Evaluate the statement. */ |
41511585 | 1213 | val = evaluate_stmt (stmt); |
4ee9c684 | 1214 | |
a065a588 | 1215 | /* If the original LHS was a VIEW_CONVERT_EXPR, modify the constant |
eb716043 | 1216 | value to be a VIEW_CONVERT_EXPR of the old constant value. |
a065a588 | 1217 | |
1218 | ??? Also, if this was a definition of a bitfield, we need to widen | |
41511585 | 1219 | the constant value into the type of the destination variable. This |
1220 | should not be necessary if GCC represented bitfields properly. */ | |
1221 | { | |
35cc02b5 | 1222 | tree orig_lhs = GIMPLE_STMT_OPERAND (stmt, 0); |
a065a588 | 1223 | |
1224 | if (TREE_CODE (orig_lhs) == VIEW_CONVERT_EXPR | |
1225 | && val.lattice_val == CONSTANT) | |
1226 | { | |
5f9acd88 | 1227 | tree w = fold_unary (VIEW_CONVERT_EXPR, |
1228 | TREE_TYPE (TREE_OPERAND (orig_lhs, 0)), | |
1229 | val.value); | |
eb716043 | 1230 | |
662f5fa5 | 1231 | orig_lhs = TREE_OPERAND (orig_lhs, 0); |
eb716043 | 1232 | if (w && is_gimple_min_invariant (w)) |
88dbf20f | 1233 | val.value = w; |
eb716043 | 1234 | else |
1235 | { | |
1236 | val.lattice_val = VARYING; | |
88dbf20f | 1237 | val.value = NULL; |
eb716043 | 1238 | } |
a065a588 | 1239 | } |
1240 | ||
41511585 | 1241 | if (val.lattice_val == CONSTANT |
a065a588 | 1242 | && TREE_CODE (orig_lhs) == COMPONENT_REF |
1243 | && DECL_BIT_FIELD (TREE_OPERAND (orig_lhs, 1))) | |
4ee9c684 | 1244 | { |
88dbf20f | 1245 | tree w = widen_bitfield (val.value, TREE_OPERAND (orig_lhs, 1), |
a065a588 | 1246 | orig_lhs); |
41511585 | 1247 | |
1248 | if (w && is_gimple_min_invariant (w)) | |
88dbf20f | 1249 | val.value = w; |
41511585 | 1250 | else |
4ee9c684 | 1251 | { |
41511585 | 1252 | val.lattice_val = VARYING; |
88dbf20f | 1253 | val.value = NULL_TREE; |
1254 | val.mem_ref = NULL_TREE; | |
4ee9c684 | 1255 | } |
4ee9c684 | 1256 | } |
41511585 | 1257 | } |
4ee9c684 | 1258 | |
88dbf20f | 1259 | retval = SSA_PROP_NOT_INTERESTING; |
4ee9c684 | 1260 | |
41511585 | 1261 | /* Set the lattice value of the statement's output. */ |
88dbf20f | 1262 | if (TREE_CODE (lhs) == SSA_NAME) |
4ee9c684 | 1263 | { |
88dbf20f | 1264 | /* If STMT is an assignment to an SSA_NAME, we only have one |
1265 | value to set. */ | |
1266 | if (set_lattice_value (lhs, val)) | |
1267 | { | |
1268 | *output_p = lhs; | |
1269 | if (val.lattice_val == VARYING) | |
1270 | retval = SSA_PROP_VARYING; | |
1271 | else | |
1272 | retval = SSA_PROP_INTERESTING; | |
1273 | } | |
4ee9c684 | 1274 | } |
88dbf20f | 1275 | else if (do_store_ccp && stmt_makes_single_store (stmt)) |
1276 | { | |
1277 | /* Otherwise, set the names in V_MAY_DEF/V_MUST_DEF operands | |
1278 | to the new constant value and mark the LHS as the memory | |
1279 | reference associated with VAL. */ | |
1280 | ssa_op_iter i; | |
1281 | tree vdef; | |
1282 | bool changed; | |
1283 | ||
88dbf20f | 1284 | /* Mark VAL as stored in the LHS of this assignment. */ |
bfa30570 | 1285 | if (val.lattice_val == CONSTANT) |
1286 | val.mem_ref = lhs; | |
88dbf20f | 1287 | |
1288 | /* Set the value of every VDEF to VAL. */ | |
1289 | changed = false; | |
1290 | FOR_EACH_SSA_TREE_OPERAND (vdef, stmt, i, SSA_OP_VIRTUAL_DEFS) | |
aecfc21d | 1291 | { |
1292 | /* See PR 29801. We may have VDEFs for read-only variables | |
1293 | (see the handling of unmodifiable variables in | |
1294 | add_virtual_operand); do not attempt to change their value. */ | |
1295 | if (get_symbol_constant_value (SSA_NAME_VAR (vdef)) != NULL_TREE) | |
1296 | continue; | |
1297 | ||
1298 | changed |= set_lattice_value (vdef, val); | |
1299 | } | |
88dbf20f | 1300 | |
1301 | /* Note that for propagation purposes, we are only interested in | |
1302 | visiting statements that load the exact same memory reference | |
1303 | stored here. Those statements will have the exact same list | |
1304 | of virtual uses, so it is enough to set the output of this | |
1305 | statement to be its first virtual definition. */ | |
1306 | *output_p = first_vdef (stmt); | |
1307 | if (changed) | |
1308 | { | |
1309 | if (val.lattice_val == VARYING) | |
1310 | retval = SSA_PROP_VARYING; | |
1311 | else | |
1312 | retval = SSA_PROP_INTERESTING; | |
1313 | } | |
1314 | } | |
1315 | ||
1316 | return retval; | |
4ee9c684 | 1317 | } |
1318 | ||
4ee9c684 | 1319 | |
41511585 | 1320 | /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING |
1321 | if it can determine which edge will be taken. Otherwise, return | |
1322 | SSA_PROP_VARYING. */ | |
1323 | ||
1324 | static enum ssa_prop_result | |
1325 | visit_cond_stmt (tree stmt, edge *taken_edge_p) | |
4ee9c684 | 1326 | { |
88dbf20f | 1327 | prop_value_t val; |
41511585 | 1328 | basic_block block; |
1329 | ||
1330 | block = bb_for_stmt (stmt); | |
1331 | val = evaluate_stmt (stmt); | |
1332 | ||
1333 | /* Find which edge out of the conditional block will be taken and add it | |
1334 | to the worklist. If no single edge can be determined statically, | |
1335 | return SSA_PROP_VARYING to feed all the outgoing edges to the | |
1336 | propagation engine. */ | |
88dbf20f | 1337 | *taken_edge_p = val.value ? find_taken_edge (block, val.value) : 0; |
41511585 | 1338 | if (*taken_edge_p) |
1339 | return SSA_PROP_INTERESTING; | |
1340 | else | |
1341 | return SSA_PROP_VARYING; | |
4ee9c684 | 1342 | } |
1343 | ||
4ee9c684 | 1344 | |
41511585 | 1345 | /* Evaluate statement STMT. If the statement produces an output value and |
1346 | its evaluation changes the lattice value of its output, return | |
1347 | SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the | |
1348 | output value. | |
1349 | ||
1350 | If STMT is a conditional branch and we can determine its truth | |
1351 | value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying | |
1352 | value, return SSA_PROP_VARYING. */ | |
4ee9c684 | 1353 | |
41511585 | 1354 | static enum ssa_prop_result |
1355 | ccp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p) | |
1356 | { | |
41511585 | 1357 | tree def; |
1358 | ssa_op_iter iter; | |
4ee9c684 | 1359 | |
41511585 | 1360 | if (dump_file && (dump_flags & TDF_DETAILS)) |
4ee9c684 | 1361 | { |
88dbf20f | 1362 | fprintf (dump_file, "\nVisiting statement:\n"); |
1363 | print_generic_stmt (dump_file, stmt, dump_flags); | |
41511585 | 1364 | fprintf (dump_file, "\n"); |
4ee9c684 | 1365 | } |
4ee9c684 | 1366 | |
35cc02b5 | 1367 | if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT) |
4ee9c684 | 1368 | { |
41511585 | 1369 | /* If the statement is an assignment that produces a single |
1370 | output value, evaluate its RHS to see if the lattice value of | |
1371 | its output has changed. */ | |
1372 | return visit_assignment (stmt, output_p); | |
4ee9c684 | 1373 | } |
41511585 | 1374 | else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR) |
4ee9c684 | 1375 | { |
41511585 | 1376 | /* If STMT is a conditional branch, see if we can determine |
1377 | which branch will be taken. */ | |
1378 | return visit_cond_stmt (stmt, taken_edge_p); | |
4ee9c684 | 1379 | } |
4ee9c684 | 1380 | |
41511585 | 1381 | /* Any other kind of statement is not interesting for constant |
1382 | propagation and, therefore, not worth simulating. */ | |
41511585 | 1383 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1384 | fprintf (dump_file, "No interesting values produced. Marked VARYING.\n"); | |
4ee9c684 | 1385 | |
41511585 | 1386 | /* Definitions made by statements other than assignments to |
1387 | SSA_NAMEs represent unknown modifications to their outputs. | |
1388 | Mark them VARYING. */ | |
88dbf20f | 1389 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) |
1390 | { | |
1391 | prop_value_t v = { VARYING, NULL_TREE, NULL_TREE }; | |
1392 | set_lattice_value (def, v); | |
1393 | } | |
4ee9c684 | 1394 | |
41511585 | 1395 | return SSA_PROP_VARYING; |
1396 | } | |
4ee9c684 | 1397 | |
4ee9c684 | 1398 | |
88dbf20f | 1399 | /* Main entry point for SSA Conditional Constant Propagation. */ |
41511585 | 1400 | |
1401 | static void | |
88dbf20f | 1402 | execute_ssa_ccp (bool store_ccp) |
41511585 | 1403 | { |
88dbf20f | 1404 | do_store_ccp = store_ccp; |
41511585 | 1405 | ccp_initialize (); |
1406 | ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node); | |
1407 | ccp_finalize (); | |
4ee9c684 | 1408 | } |
1409 | ||
5664499b | 1410 | |
2a1990e9 | 1411 | static unsigned int |
88dbf20f | 1412 | do_ssa_ccp (void) |
1413 | { | |
1414 | execute_ssa_ccp (false); | |
2a1990e9 | 1415 | return 0; |
88dbf20f | 1416 | } |
1417 | ||
1418 | ||
5664499b | 1419 | static bool |
41511585 | 1420 | gate_ccp (void) |
5664499b | 1421 | { |
41511585 | 1422 | return flag_tree_ccp != 0; |
5664499b | 1423 | } |
1424 | ||
4ee9c684 | 1425 | |
41511585 | 1426 | struct tree_opt_pass pass_ccp = |
1427 | { | |
1428 | "ccp", /* name */ | |
1429 | gate_ccp, /* gate */ | |
88dbf20f | 1430 | do_ssa_ccp, /* execute */ |
41511585 | 1431 | NULL, /* sub */ |
1432 | NULL, /* next */ | |
1433 | 0, /* static_pass_number */ | |
1434 | TV_TREE_CCP, /* tv_id */ | |
1435 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ | |
1436 | 0, /* properties_provided */ | |
b6246c40 | 1437 | 0, /* properties_destroyed */ |
41511585 | 1438 | 0, /* todo_flags_start */ |
88dbf20f | 1439 | TODO_cleanup_cfg | TODO_dump_func | TODO_update_ssa |
41511585 | 1440 | | TODO_ggc_collect | TODO_verify_ssa |
eff665b7 | 1441 | | TODO_verify_stmts | TODO_update_smt_usage, /* todo_flags_finish */ |
0f9005dd | 1442 | 0 /* letter */ |
41511585 | 1443 | }; |
4ee9c684 | 1444 | |
4ee9c684 | 1445 | |
2a1990e9 | 1446 | static unsigned int |
88dbf20f | 1447 | do_ssa_store_ccp (void) |
1448 | { | |
1449 | /* If STORE-CCP is not enabled, we just run regular CCP. */ | |
1450 | execute_ssa_ccp (flag_tree_store_ccp != 0); | |
2a1990e9 | 1451 | return 0; |
88dbf20f | 1452 | } |
1453 | ||
1454 | static bool | |
1455 | gate_store_ccp (void) | |
1456 | { | |
1457 | /* STORE-CCP is enabled only with -ftree-store-ccp, but when | |
1458 | -fno-tree-store-ccp is specified, we should run regular CCP. | |
1459 | That's why the pass is enabled with either flag. */ | |
1460 | return flag_tree_store_ccp != 0 || flag_tree_ccp != 0; | |
1461 | } | |
1462 | ||
1463 | ||
1464 | struct tree_opt_pass pass_store_ccp = | |
1465 | { | |
1466 | "store_ccp", /* name */ | |
1467 | gate_store_ccp, /* gate */ | |
1468 | do_ssa_store_ccp, /* execute */ | |
1469 | NULL, /* sub */ | |
1470 | NULL, /* next */ | |
1471 | 0, /* static_pass_number */ | |
1472 | TV_TREE_STORE_CCP, /* tv_id */ | |
1473 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ | |
1474 | 0, /* properties_provided */ | |
b6246c40 | 1475 | 0, /* properties_destroyed */ |
88dbf20f | 1476 | 0, /* todo_flags_start */ |
1477 | TODO_dump_func | TODO_update_ssa | |
1478 | | TODO_ggc_collect | TODO_verify_ssa | |
1479 | | TODO_cleanup_cfg | |
eff665b7 | 1480 | | TODO_verify_stmts | TODO_update_smt_usage, /* todo_flags_finish */ |
88dbf20f | 1481 | 0 /* letter */ |
1482 | }; | |
1483 | ||
41511585 | 1484 | /* Given a constant value VAL for bitfield FIELD, and a destination |
1485 | variable VAR, return VAL appropriately widened to fit into VAR. If | |
1486 | FIELD is wider than HOST_WIDE_INT, NULL is returned. */ | |
4ee9c684 | 1487 | |
41511585 | 1488 | tree |
1489 | widen_bitfield (tree val, tree field, tree var) | |
4ee9c684 | 1490 | { |
41511585 | 1491 | unsigned HOST_WIDE_INT var_size, field_size; |
1492 | tree wide_val; | |
1493 | unsigned HOST_WIDE_INT mask; | |
1494 | unsigned int i; | |
4ee9c684 | 1495 | |
41511585 | 1496 | /* We can only do this if the size of the type and field and VAL are |
1497 | all constants representable in HOST_WIDE_INT. */ | |
1498 | if (!host_integerp (TYPE_SIZE (TREE_TYPE (var)), 1) | |
1499 | || !host_integerp (DECL_SIZE (field), 1) | |
1500 | || !host_integerp (val, 0)) | |
1501 | return NULL_TREE; | |
4ee9c684 | 1502 | |
41511585 | 1503 | var_size = tree_low_cst (TYPE_SIZE (TREE_TYPE (var)), 1); |
1504 | field_size = tree_low_cst (DECL_SIZE (field), 1); | |
4ee9c684 | 1505 | |
41511585 | 1506 | /* Give up if either the bitfield or the variable are too wide. */ |
1507 | if (field_size > HOST_BITS_PER_WIDE_INT || var_size > HOST_BITS_PER_WIDE_INT) | |
1508 | return NULL_TREE; | |
4ee9c684 | 1509 | |
8c0963c4 | 1510 | gcc_assert (var_size >= field_size); |
4ee9c684 | 1511 | |
41511585 | 1512 | /* If the sign bit of the value is not set or the field's type is unsigned, |
1513 | just mask off the high order bits of the value. */ | |
1514 | if (DECL_UNSIGNED (field) | |
1515 | || !(tree_low_cst (val, 0) & (((HOST_WIDE_INT)1) << (field_size - 1)))) | |
1516 | { | |
1517 | /* Zero extension. Build a mask with the lower 'field_size' bits | |
1518 | set and a BIT_AND_EXPR node to clear the high order bits of | |
1519 | the value. */ | |
1520 | for (i = 0, mask = 0; i < field_size; i++) | |
1521 | mask |= ((HOST_WIDE_INT) 1) << i; | |
4ee9c684 | 1522 | |
e7be49a3 | 1523 | wide_val = fold_build2 (BIT_AND_EXPR, TREE_TYPE (var), val, |
1524 | build_int_cst (TREE_TYPE (var), mask)); | |
4ee9c684 | 1525 | } |
41511585 | 1526 | else |
5664499b | 1527 | { |
41511585 | 1528 | /* Sign extension. Create a mask with the upper 'field_size' |
1529 | bits set and a BIT_IOR_EXPR to set the high order bits of the | |
1530 | value. */ | |
1531 | for (i = 0, mask = 0; i < (var_size - field_size); i++) | |
1532 | mask |= ((HOST_WIDE_INT) 1) << (var_size - i - 1); | |
1533 | ||
e7be49a3 | 1534 | wide_val = fold_build2 (BIT_IOR_EXPR, TREE_TYPE (var), val, |
1535 | build_int_cst (TREE_TYPE (var), mask)); | |
5664499b | 1536 | } |
4ee9c684 | 1537 | |
e7be49a3 | 1538 | return wide_val; |
4ee9c684 | 1539 | } |
1540 | ||
41511585 | 1541 | |
4ee9c684 | 1542 | /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X]. |
1543 | BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE | |
0bed3869 | 1544 | is the desired result type. */ |
4ee9c684 | 1545 | |
1546 | static tree | |
1547 | maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type) | |
1548 | { | |
6374121b | 1549 | tree min_idx, idx, elt_offset = integer_zero_node; |
1550 | tree array_type, elt_type, elt_size; | |
1551 | ||
1552 | /* If BASE is an ARRAY_REF, we can pick up another offset (this time | |
1553 | measured in units of the size of elements type) from that ARRAY_REF). | |
1554 | We can't do anything if either is variable. | |
1555 | ||
1556 | The case we handle here is *(&A[N]+O). */ | |
1557 | if (TREE_CODE (base) == ARRAY_REF) | |
1558 | { | |
1559 | tree low_bound = array_ref_low_bound (base); | |
1560 | ||
1561 | elt_offset = TREE_OPERAND (base, 1); | |
1562 | if (TREE_CODE (low_bound) != INTEGER_CST | |
1563 | || TREE_CODE (elt_offset) != INTEGER_CST) | |
1564 | return NULL_TREE; | |
1565 | ||
1566 | elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0); | |
1567 | base = TREE_OPERAND (base, 0); | |
1568 | } | |
4ee9c684 | 1569 | |
1570 | /* Ignore stupid user tricks of indexing non-array variables. */ | |
1571 | array_type = TREE_TYPE (base); | |
1572 | if (TREE_CODE (array_type) != ARRAY_TYPE) | |
1573 | return NULL_TREE; | |
1574 | elt_type = TREE_TYPE (array_type); | |
1575 | if (!lang_hooks.types_compatible_p (orig_type, elt_type)) | |
1576 | return NULL_TREE; | |
1577 | ||
6374121b | 1578 | /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the |
1579 | element type (so we can use the alignment if it's not constant). | |
1580 | Otherwise, compute the offset as an index by using a division. If the | |
1581 | division isn't exact, then don't do anything. */ | |
4ee9c684 | 1582 | elt_size = TYPE_SIZE_UNIT (elt_type); |
6374121b | 1583 | if (integer_zerop (offset)) |
1584 | { | |
1585 | if (TREE_CODE (elt_size) != INTEGER_CST) | |
1586 | elt_size = size_int (TYPE_ALIGN (elt_type)); | |
4ee9c684 | 1587 | |
6374121b | 1588 | idx = integer_zero_node; |
1589 | } | |
1590 | else | |
1591 | { | |
1592 | unsigned HOST_WIDE_INT lquo, lrem; | |
1593 | HOST_WIDE_INT hquo, hrem; | |
1594 | ||
1595 | if (TREE_CODE (elt_size) != INTEGER_CST | |
1596 | || div_and_round_double (TRUNC_DIV_EXPR, 1, | |
1597 | TREE_INT_CST_LOW (offset), | |
1598 | TREE_INT_CST_HIGH (offset), | |
1599 | TREE_INT_CST_LOW (elt_size), | |
1600 | TREE_INT_CST_HIGH (elt_size), | |
1601 | &lquo, &hquo, &lrem, &hrem) | |
1602 | || lrem || hrem) | |
1603 | return NULL_TREE; | |
4ee9c684 | 1604 | |
7016c612 | 1605 | idx = build_int_cst_wide (NULL_TREE, lquo, hquo); |
6374121b | 1606 | } |
1607 | ||
1608 | /* Assume the low bound is zero. If there is a domain type, get the | |
1609 | low bound, if any, convert the index into that type, and add the | |
1610 | low bound. */ | |
1611 | min_idx = integer_zero_node; | |
1612 | if (TYPE_DOMAIN (array_type)) | |
4ee9c684 | 1613 | { |
6374121b | 1614 | if (TYPE_MIN_VALUE (TYPE_DOMAIN (array_type))) |
1615 | min_idx = TYPE_MIN_VALUE (TYPE_DOMAIN (array_type)); | |
1616 | else | |
1617 | min_idx = fold_convert (TYPE_DOMAIN (array_type), min_idx); | |
1618 | ||
1619 | if (TREE_CODE (min_idx) != INTEGER_CST) | |
1620 | return NULL_TREE; | |
1621 | ||
1622 | idx = fold_convert (TYPE_DOMAIN (array_type), idx); | |
1623 | elt_offset = fold_convert (TYPE_DOMAIN (array_type), elt_offset); | |
4ee9c684 | 1624 | } |
1625 | ||
6374121b | 1626 | if (!integer_zerop (min_idx)) |
1627 | idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0); | |
1628 | if (!integer_zerop (elt_offset)) | |
1629 | idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0); | |
1630 | ||
40b19772 | 1631 | return build4 (ARRAY_REF, orig_type, base, idx, min_idx, |
1632 | size_int (tree_low_cst (elt_size, 1) | |
1633 | / (TYPE_ALIGN_UNIT (elt_type)))); | |
4ee9c684 | 1634 | } |
1635 | ||
41511585 | 1636 | |
4ee9c684 | 1637 | /* A subroutine of fold_stmt_r. Attempts to fold *(S+O) to S.X. |
1638 | BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE | |
1639 | is the desired result type. */ | |
1640 | /* ??? This doesn't handle class inheritance. */ | |
1641 | ||
1642 | static tree | |
1643 | maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset, | |
1644 | tree orig_type, bool base_is_ptr) | |
1645 | { | |
6d5d8428 | 1646 | tree f, t, field_type, tail_array_field, field_offset; |
4ee9c684 | 1647 | |
1648 | if (TREE_CODE (record_type) != RECORD_TYPE | |
1649 | && TREE_CODE (record_type) != UNION_TYPE | |
1650 | && TREE_CODE (record_type) != QUAL_UNION_TYPE) | |
1651 | return NULL_TREE; | |
1652 | ||
1653 | /* Short-circuit silly cases. */ | |
1654 | if (lang_hooks.types_compatible_p (record_type, orig_type)) | |
1655 | return NULL_TREE; | |
1656 | ||
1657 | tail_array_field = NULL_TREE; | |
1658 | for (f = TYPE_FIELDS (record_type); f ; f = TREE_CHAIN (f)) | |
1659 | { | |
1660 | int cmp; | |
1661 | ||
1662 | if (TREE_CODE (f) != FIELD_DECL) | |
1663 | continue; | |
1664 | if (DECL_BIT_FIELD (f)) | |
1665 | continue; | |
6d5d8428 | 1666 | |
1667 | field_offset = byte_position (f); | |
1668 | if (TREE_CODE (field_offset) != INTEGER_CST) | |
4ee9c684 | 1669 | continue; |
1670 | ||
1671 | /* ??? Java creates "interesting" fields for representing base classes. | |
1672 | They have no name, and have no context. With no context, we get into | |
1673 | trouble with nonoverlapping_component_refs_p. Skip them. */ | |
1674 | if (!DECL_FIELD_CONTEXT (f)) | |
1675 | continue; | |
1676 | ||
1677 | /* The previous array field isn't at the end. */ | |
1678 | tail_array_field = NULL_TREE; | |
1679 | ||
1680 | /* Check to see if this offset overlaps with the field. */ | |
6d5d8428 | 1681 | cmp = tree_int_cst_compare (field_offset, offset); |
4ee9c684 | 1682 | if (cmp > 0) |
1683 | continue; | |
1684 | ||
1685 | field_type = TREE_TYPE (f); | |
4ee9c684 | 1686 | |
1687 | /* Here we exactly match the offset being checked. If the types match, | |
1688 | then we can return that field. */ | |
115073ff | 1689 | if (cmp == 0 |
1690 | && lang_hooks.types_compatible_p (orig_type, field_type)) | |
4ee9c684 | 1691 | { |
1692 | if (base_is_ptr) | |
1693 | base = build1 (INDIRECT_REF, record_type, base); | |
40b19772 | 1694 | t = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE); |
4ee9c684 | 1695 | return t; |
1696 | } | |
115073ff | 1697 | |
1698 | /* Don't care about offsets into the middle of scalars. */ | |
1699 | if (!AGGREGATE_TYPE_P (field_type)) | |
1700 | continue; | |
4ee9c684 | 1701 | |
115073ff | 1702 | /* Check for array at the end of the struct. This is often |
1703 | used as for flexible array members. We should be able to | |
1704 | turn this into an array access anyway. */ | |
1705 | if (TREE_CODE (field_type) == ARRAY_TYPE) | |
1706 | tail_array_field = f; | |
1707 | ||
1708 | /* Check the end of the field against the offset. */ | |
1709 | if (!DECL_SIZE_UNIT (f) | |
1710 | || TREE_CODE (DECL_SIZE_UNIT (f)) != INTEGER_CST) | |
1711 | continue; | |
1712 | t = int_const_binop (MINUS_EXPR, offset, field_offset, 1); | |
1713 | if (!tree_int_cst_lt (t, DECL_SIZE_UNIT (f))) | |
1714 | continue; | |
4ee9c684 | 1715 | |
115073ff | 1716 | /* If we matched, then set offset to the displacement into |
1717 | this field. */ | |
1718 | offset = t; | |
4ee9c684 | 1719 | goto found; |
1720 | } | |
1721 | ||
1722 | if (!tail_array_field) | |
1723 | return NULL_TREE; | |
1724 | ||
1725 | f = tail_array_field; | |
1726 | field_type = TREE_TYPE (f); | |
115073ff | 1727 | offset = int_const_binop (MINUS_EXPR, offset, byte_position (f), 1); |
4ee9c684 | 1728 | |
1729 | found: | |
1730 | /* If we get here, we've got an aggregate field, and a possibly | |
365db11e | 1731 | nonzero offset into them. Recurse and hope for a valid match. */ |
4ee9c684 | 1732 | if (base_is_ptr) |
1733 | base = build1 (INDIRECT_REF, record_type, base); | |
40b19772 | 1734 | base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE); |
4ee9c684 | 1735 | |
1736 | t = maybe_fold_offset_to_array_ref (base, offset, orig_type); | |
1737 | if (t) | |
1738 | return t; | |
1739 | return maybe_fold_offset_to_component_ref (field_type, base, offset, | |
1740 | orig_type, false); | |
1741 | } | |
1742 | ||
41511585 | 1743 | |
4ee9c684 | 1744 | /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET). |
1745 | Return the simplified expression, or NULL if nothing could be done. */ | |
1746 | ||
1747 | static tree | |
1748 | maybe_fold_stmt_indirect (tree expr, tree base, tree offset) | |
1749 | { | |
1750 | tree t; | |
1751 | ||
1752 | /* We may well have constructed a double-nested PLUS_EXPR via multiple | |
1753 | substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that | |
1754 | are sometimes added. */ | |
1755 | base = fold (base); | |
40bcfc86 | 1756 | STRIP_TYPE_NOPS (base); |
4ee9c684 | 1757 | TREE_OPERAND (expr, 0) = base; |
1758 | ||
1759 | /* One possibility is that the address reduces to a string constant. */ | |
1760 | t = fold_read_from_constant_string (expr); | |
1761 | if (t) | |
1762 | return t; | |
1763 | ||
1764 | /* Add in any offset from a PLUS_EXPR. */ | |
1765 | if (TREE_CODE (base) == PLUS_EXPR) | |
1766 | { | |
1767 | tree offset2; | |
1768 | ||
1769 | offset2 = TREE_OPERAND (base, 1); | |
1770 | if (TREE_CODE (offset2) != INTEGER_CST) | |
1771 | return NULL_TREE; | |
1772 | base = TREE_OPERAND (base, 0); | |
1773 | ||
1774 | offset = int_const_binop (PLUS_EXPR, offset, offset2, 1); | |
1775 | } | |
1776 | ||
1777 | if (TREE_CODE (base) == ADDR_EXPR) | |
1778 | { | |
1779 | /* Strip the ADDR_EXPR. */ | |
1780 | base = TREE_OPERAND (base, 0); | |
1781 | ||
e67e5e1f | 1782 | /* Fold away CONST_DECL to its value, if the type is scalar. */ |
1783 | if (TREE_CODE (base) == CONST_DECL | |
d03bd588 | 1784 | && ccp_decl_initial_min_invariant (DECL_INITIAL (base))) |
e67e5e1f | 1785 | return DECL_INITIAL (base); |
1786 | ||
4ee9c684 | 1787 | /* Try folding *(&B+O) to B[X]. */ |
1788 | t = maybe_fold_offset_to_array_ref (base, offset, TREE_TYPE (expr)); | |
1789 | if (t) | |
1790 | return t; | |
1791 | ||
1792 | /* Try folding *(&B+O) to B.X. */ | |
1793 | t = maybe_fold_offset_to_component_ref (TREE_TYPE (base), base, offset, | |
1794 | TREE_TYPE (expr), false); | |
1795 | if (t) | |
1796 | return t; | |
1797 | ||
6374121b | 1798 | /* Fold *&B to B. We can only do this if EXPR is the same type |
1799 | as BASE. We can't do this if EXPR is the element type of an array | |
1800 | and BASE is the array. */ | |
1801 | if (integer_zerop (offset) | |
1802 | && lang_hooks.types_compatible_p (TREE_TYPE (base), | |
1803 | TREE_TYPE (expr))) | |
4ee9c684 | 1804 | return base; |
1805 | } | |
1806 | else | |
1807 | { | |
1808 | /* We can get here for out-of-range string constant accesses, | |
1809 | such as "_"[3]. Bail out of the entire substitution search | |
1810 | and arrange for the entire statement to be replaced by a | |
06b27565 | 1811 | call to __builtin_trap. In all likelihood this will all be |
4ee9c684 | 1812 | constant-folded away, but in the meantime we can't leave with |
1813 | something that get_expr_operands can't understand. */ | |
1814 | ||
1815 | t = base; | |
1816 | STRIP_NOPS (t); | |
1817 | if (TREE_CODE (t) == ADDR_EXPR | |
1818 | && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST) | |
1819 | { | |
1820 | /* FIXME: Except that this causes problems elsewhere with dead | |
1fa3a8f6 | 1821 | code not being deleted, and we die in the rtl expanders |
4ee9c684 | 1822 | because we failed to remove some ssa_name. In the meantime, |
1823 | just return zero. */ | |
1824 | /* FIXME2: This condition should be signaled by | |
1825 | fold_read_from_constant_string directly, rather than | |
1826 | re-checking for it here. */ | |
1827 | return integer_zero_node; | |
1828 | } | |
1829 | ||
1830 | /* Try folding *(B+O) to B->X. Still an improvement. */ | |
1831 | if (POINTER_TYPE_P (TREE_TYPE (base))) | |
1832 | { | |
1833 | t = maybe_fold_offset_to_component_ref (TREE_TYPE (TREE_TYPE (base)), | |
1834 | base, offset, | |
1835 | TREE_TYPE (expr), true); | |
1836 | if (t) | |
1837 | return t; | |
1838 | } | |
1839 | } | |
1840 | ||
1841 | /* Otherwise we had an offset that we could not simplify. */ | |
1842 | return NULL_TREE; | |
1843 | } | |
1844 | ||
41511585 | 1845 | |
4ee9c684 | 1846 | /* A subroutine of fold_stmt_r. EXPR is a PLUS_EXPR. |
1847 | ||
1848 | A quaint feature extant in our address arithmetic is that there | |
1849 | can be hidden type changes here. The type of the result need | |
1850 | not be the same as the type of the input pointer. | |
1851 | ||
1852 | What we're after here is an expression of the form | |
1853 | (T *)(&array + const) | |
1854 | where the cast doesn't actually exist, but is implicit in the | |
1855 | type of the PLUS_EXPR. We'd like to turn this into | |
1856 | &array[x] | |
1857 | which may be able to propagate further. */ | |
1858 | ||
1859 | static tree | |
1860 | maybe_fold_stmt_addition (tree expr) | |
1861 | { | |
1862 | tree op0 = TREE_OPERAND (expr, 0); | |
1863 | tree op1 = TREE_OPERAND (expr, 1); | |
1864 | tree ptr_type = TREE_TYPE (expr); | |
1865 | tree ptd_type; | |
1866 | tree t; | |
1867 | bool subtract = (TREE_CODE (expr) == MINUS_EXPR); | |
1868 | ||
1869 | /* We're only interested in pointer arithmetic. */ | |
1870 | if (!POINTER_TYPE_P (ptr_type)) | |
1871 | return NULL_TREE; | |
1872 | /* Canonicalize the integral operand to op1. */ | |
1873 | if (INTEGRAL_TYPE_P (TREE_TYPE (op0))) | |
1874 | { | |
1875 | if (subtract) | |
1876 | return NULL_TREE; | |
1877 | t = op0, op0 = op1, op1 = t; | |
1878 | } | |
1879 | /* It had better be a constant. */ | |
1880 | if (TREE_CODE (op1) != INTEGER_CST) | |
1881 | return NULL_TREE; | |
1882 | /* The first operand should be an ADDR_EXPR. */ | |
1883 | if (TREE_CODE (op0) != ADDR_EXPR) | |
1884 | return NULL_TREE; | |
1885 | op0 = TREE_OPERAND (op0, 0); | |
1886 | ||
1887 | /* If the first operand is an ARRAY_REF, expand it so that we can fold | |
1888 | the offset into it. */ | |
1889 | while (TREE_CODE (op0) == ARRAY_REF) | |
1890 | { | |
1891 | tree array_obj = TREE_OPERAND (op0, 0); | |
1892 | tree array_idx = TREE_OPERAND (op0, 1); | |
1893 | tree elt_type = TREE_TYPE (op0); | |
1894 | tree elt_size = TYPE_SIZE_UNIT (elt_type); | |
1895 | tree min_idx; | |
1896 | ||
1897 | if (TREE_CODE (array_idx) != INTEGER_CST) | |
1898 | break; | |
1899 | if (TREE_CODE (elt_size) != INTEGER_CST) | |
1900 | break; | |
1901 | ||
1902 | /* Un-bias the index by the min index of the array type. */ | |
1903 | min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj)); | |
1904 | if (min_idx) | |
1905 | { | |
1906 | min_idx = TYPE_MIN_VALUE (min_idx); | |
1907 | if (min_idx) | |
1908 | { | |
6374121b | 1909 | if (TREE_CODE (min_idx) != INTEGER_CST) |
1910 | break; | |
1911 | ||
535664e3 | 1912 | array_idx = fold_convert (TREE_TYPE (min_idx), array_idx); |
4ee9c684 | 1913 | if (!integer_zerop (min_idx)) |
1914 | array_idx = int_const_binop (MINUS_EXPR, array_idx, | |
1915 | min_idx, 0); | |
1916 | } | |
1917 | } | |
1918 | ||
1919 | /* Convert the index to a byte offset. */ | |
535664e3 | 1920 | array_idx = fold_convert (sizetype, array_idx); |
4ee9c684 | 1921 | array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0); |
1922 | ||
1923 | /* Update the operands for the next round, or for folding. */ | |
1924 | /* If we're manipulating unsigned types, then folding into negative | |
1925 | values can produce incorrect results. Particularly if the type | |
1926 | is smaller than the width of the pointer. */ | |
1927 | if (subtract | |
1928 | && TYPE_UNSIGNED (TREE_TYPE (op1)) | |
1929 | && tree_int_cst_lt (array_idx, op1)) | |
1930 | return NULL; | |
1931 | op1 = int_const_binop (subtract ? MINUS_EXPR : PLUS_EXPR, | |
1932 | array_idx, op1, 0); | |
1933 | subtract = false; | |
1934 | op0 = array_obj; | |
1935 | } | |
1936 | ||
1937 | /* If we weren't able to fold the subtraction into another array reference, | |
1938 | canonicalize the integer for passing to the array and component ref | |
1939 | simplification functions. */ | |
1940 | if (subtract) | |
1941 | { | |
1942 | if (TYPE_UNSIGNED (TREE_TYPE (op1))) | |
1943 | return NULL; | |
5f9acd88 | 1944 | op1 = fold_unary (NEGATE_EXPR, TREE_TYPE (op1), op1); |
4ee9c684 | 1945 | /* ??? In theory fold should always produce another integer. */ |
5f9acd88 | 1946 | if (op1 == NULL || TREE_CODE (op1) != INTEGER_CST) |
4ee9c684 | 1947 | return NULL; |
1948 | } | |
1949 | ||
1950 | ptd_type = TREE_TYPE (ptr_type); | |
1951 | ||
1952 | /* At which point we can try some of the same things as for indirects. */ | |
1953 | t = maybe_fold_offset_to_array_ref (op0, op1, ptd_type); | |
1954 | if (!t) | |
1955 | t = maybe_fold_offset_to_component_ref (TREE_TYPE (op0), op0, op1, | |
1956 | ptd_type, false); | |
1957 | if (t) | |
1958 | t = build1 (ADDR_EXPR, ptr_type, t); | |
1959 | ||
1960 | return t; | |
1961 | } | |
1962 | ||
0d759d9c | 1963 | /* For passing state through walk_tree into fold_stmt_r and its |
1964 | children. */ | |
1965 | ||
1966 | struct fold_stmt_r_data | |
1967 | { | |
1968 | bool *changed_p; | |
1969 | bool *inside_addr_expr_p; | |
1970 | }; | |
1971 | ||
4ee9c684 | 1972 | /* Subroutine of fold_stmt called via walk_tree. We perform several |
1973 | simplifications of EXPR_P, mostly having to do with pointer arithmetic. */ | |
1974 | ||
1975 | static tree | |
1976 | fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data) | |
1977 | { | |
680a19b9 | 1978 | struct fold_stmt_r_data *fold_stmt_r_data = (struct fold_stmt_r_data *) data; |
0d759d9c | 1979 | bool *inside_addr_expr_p = fold_stmt_r_data->inside_addr_expr_p; |
1980 | bool *changed_p = fold_stmt_r_data->changed_p; | |
4ee9c684 | 1981 | tree expr = *expr_p, t; |
1982 | ||
1983 | /* ??? It'd be nice if walk_tree had a pre-order option. */ | |
1984 | switch (TREE_CODE (expr)) | |
1985 | { | |
1986 | case INDIRECT_REF: | |
1987 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
1988 | if (t) | |
1989 | return t; | |
1990 | *walk_subtrees = 0; | |
1991 | ||
1992 | t = maybe_fold_stmt_indirect (expr, TREE_OPERAND (expr, 0), | |
1993 | integer_zero_node); | |
1994 | break; | |
1995 | ||
0d759d9c | 1996 | /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF. |
4ee9c684 | 1997 | We'd only want to bother decomposing an existing ARRAY_REF if |
1998 | the base array is found to have another offset contained within. | |
1999 | Otherwise we'd be wasting time. */ | |
0d759d9c | 2000 | case ARRAY_REF: |
2001 | /* If we are not processing expressions found within an | |
2002 | ADDR_EXPR, then we can fold constant array references. */ | |
2003 | if (!*inside_addr_expr_p) | |
2004 | t = fold_read_from_constant_string (expr); | |
2005 | else | |
2006 | t = NULL; | |
2007 | break; | |
4ee9c684 | 2008 | |
2009 | case ADDR_EXPR: | |
0d759d9c | 2010 | *inside_addr_expr_p = true; |
4ee9c684 | 2011 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); |
0d759d9c | 2012 | *inside_addr_expr_p = false; |
4ee9c684 | 2013 | if (t) |
2014 | return t; | |
2015 | *walk_subtrees = 0; | |
2016 | ||
2017 | /* Set TREE_INVARIANT properly so that the value is properly | |
2018 | considered constant, and so gets propagated as expected. */ | |
2019 | if (*changed_p) | |
750ad201 | 2020 | recompute_tree_invariant_for_addr_expr (expr); |
4ee9c684 | 2021 | return NULL_TREE; |
2022 | ||
2023 | case PLUS_EXPR: | |
2024 | case MINUS_EXPR: | |
2025 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
2026 | if (t) | |
2027 | return t; | |
2028 | t = walk_tree (&TREE_OPERAND (expr, 1), fold_stmt_r, data, NULL); | |
2029 | if (t) | |
2030 | return t; | |
2031 | *walk_subtrees = 0; | |
2032 | ||
2033 | t = maybe_fold_stmt_addition (expr); | |
2034 | break; | |
2035 | ||
2036 | case COMPONENT_REF: | |
2037 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
2038 | if (t) | |
2039 | return t; | |
2040 | *walk_subtrees = 0; | |
2041 | ||
504d3463 | 2042 | /* Make sure the FIELD_DECL is actually a field in the type on the lhs. |
2043 | We've already checked that the records are compatible, so we should | |
2044 | come up with a set of compatible fields. */ | |
2045 | { | |
2046 | tree expr_record = TREE_TYPE (TREE_OPERAND (expr, 0)); | |
2047 | tree expr_field = TREE_OPERAND (expr, 1); | |
2048 | ||
2049 | if (DECL_FIELD_CONTEXT (expr_field) != TYPE_MAIN_VARIANT (expr_record)) | |
2050 | { | |
2051 | expr_field = find_compatible_field (expr_record, expr_field); | |
2052 | TREE_OPERAND (expr, 1) = expr_field; | |
2053 | } | |
2054 | } | |
4ee9c684 | 2055 | break; |
2056 | ||
aed164c3 | 2057 | case TARGET_MEM_REF: |
2058 | t = maybe_fold_tmr (expr); | |
2059 | break; | |
2060 | ||
bb8a9715 | 2061 | case COND_EXPR: |
2062 | if (COMPARISON_CLASS_P (TREE_OPERAND (expr, 0))) | |
2063 | { | |
2064 | tree op0 = TREE_OPERAND (expr, 0); | |
2065 | tree tem = fold_binary (TREE_CODE (op0), TREE_TYPE (op0), | |
f2532264 | 2066 | TREE_OPERAND (op0, 0), |
2067 | TREE_OPERAND (op0, 1)); | |
2068 | if (tem && set_rhs (expr_p, tem)) | |
2069 | { | |
2070 | t = *expr_p; | |
2071 | break; | |
2072 | } | |
bb8a9715 | 2073 | } |
f2532264 | 2074 | return NULL_TREE; |
bb8a9715 | 2075 | |
4ee9c684 | 2076 | default: |
2077 | return NULL_TREE; | |
2078 | } | |
2079 | ||
2080 | if (t) | |
2081 | { | |
2082 | *expr_p = t; | |
2083 | *changed_p = true; | |
2084 | } | |
2085 | ||
2086 | return NULL_TREE; | |
2087 | } | |
2088 | ||
4ee9c684 | 2089 | |
0a39fd54 | 2090 | /* Return the string length, maximum string length or maximum value of |
2091 | ARG in LENGTH. | |
2092 | If ARG is an SSA name variable, follow its use-def chains. If LENGTH | |
2093 | is not NULL and, for TYPE == 0, its value is not equal to the length | |
2094 | we determine or if we are unable to determine the length or value, | |
2095 | return false. VISITED is a bitmap of visited variables. | |
2096 | TYPE is 0 if string length should be returned, 1 for maximum string | |
2097 | length and 2 for maximum value ARG can have. */ | |
4ee9c684 | 2098 | |
72648a0e | 2099 | static bool |
0a39fd54 | 2100 | get_maxval_strlen (tree arg, tree *length, bitmap visited, int type) |
4ee9c684 | 2101 | { |
41511585 | 2102 | tree var, def_stmt, val; |
2103 | ||
2104 | if (TREE_CODE (arg) != SSA_NAME) | |
72648a0e | 2105 | { |
0a39fd54 | 2106 | if (type == 2) |
2107 | { | |
2108 | val = arg; | |
2109 | if (TREE_CODE (val) != INTEGER_CST | |
2110 | || tree_int_cst_sgn (val) < 0) | |
2111 | return false; | |
2112 | } | |
2113 | else | |
2114 | val = c_strlen (arg, 1); | |
41511585 | 2115 | if (!val) |
72648a0e | 2116 | return false; |
e37235f0 | 2117 | |
0a39fd54 | 2118 | if (*length) |
2119 | { | |
2120 | if (type > 0) | |
2121 | { | |
2122 | if (TREE_CODE (*length) != INTEGER_CST | |
2123 | || TREE_CODE (val) != INTEGER_CST) | |
2124 | return false; | |
2125 | ||
2126 | if (tree_int_cst_lt (*length, val)) | |
2127 | *length = val; | |
2128 | return true; | |
2129 | } | |
2130 | else if (simple_cst_equal (val, *length) != 1) | |
2131 | return false; | |
2132 | } | |
4ee9c684 | 2133 | |
41511585 | 2134 | *length = val; |
2135 | return true; | |
4ee9c684 | 2136 | } |
72648a0e | 2137 | |
41511585 | 2138 | /* If we were already here, break the infinite cycle. */ |
2139 | if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg))) | |
2140 | return true; | |
2141 | bitmap_set_bit (visited, SSA_NAME_VERSION (arg)); | |
2142 | ||
2143 | var = arg; | |
2144 | def_stmt = SSA_NAME_DEF_STMT (var); | |
4ee9c684 | 2145 | |
41511585 | 2146 | switch (TREE_CODE (def_stmt)) |
2147 | { | |
35cc02b5 | 2148 | case GIMPLE_MODIFY_STMT: |
41511585 | 2149 | { |
0a39fd54 | 2150 | tree rhs; |
2151 | ||
41511585 | 2152 | /* The RHS of the statement defining VAR must either have a |
2153 | constant length or come from another SSA_NAME with a constant | |
2154 | length. */ | |
35cc02b5 | 2155 | rhs = GIMPLE_STMT_OPERAND (def_stmt, 1); |
41511585 | 2156 | STRIP_NOPS (rhs); |
0a39fd54 | 2157 | return get_maxval_strlen (rhs, length, visited, type); |
41511585 | 2158 | } |
4ee9c684 | 2159 | |
41511585 | 2160 | case PHI_NODE: |
2161 | { | |
2162 | /* All the arguments of the PHI node must have the same constant | |
2163 | length. */ | |
2164 | int i; | |
4ee9c684 | 2165 | |
41511585 | 2166 | for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++) |
2167 | { | |
2168 | tree arg = PHI_ARG_DEF (def_stmt, i); | |
4ee9c684 | 2169 | |
41511585 | 2170 | /* If this PHI has itself as an argument, we cannot |
2171 | determine the string length of this argument. However, | |
2172 | if we can find a constant string length for the other | |
2173 | PHI args then we can still be sure that this is a | |
2174 | constant string length. So be optimistic and just | |
2175 | continue with the next argument. */ | |
2176 | if (arg == PHI_RESULT (def_stmt)) | |
2177 | continue; | |
4ee9c684 | 2178 | |
0a39fd54 | 2179 | if (!get_maxval_strlen (arg, length, visited, type)) |
41511585 | 2180 | return false; |
2181 | } | |
4ee9c684 | 2182 | |
41511585 | 2183 | return true; |
5664499b | 2184 | } |
4ee9c684 | 2185 | |
41511585 | 2186 | default: |
2187 | break; | |
4ee9c684 | 2188 | } |
2189 | ||
41511585 | 2190 | |
2191 | return false; | |
4ee9c684 | 2192 | } |
2193 | ||
2194 | ||
2195 | /* Fold builtin call FN in statement STMT. If it cannot be folded into a | |
2196 | constant, return NULL_TREE. Otherwise, return its constant value. */ | |
2197 | ||
2198 | static tree | |
2199 | ccp_fold_builtin (tree stmt, tree fn) | |
2200 | { | |
0a39fd54 | 2201 | tree result, val[3]; |
f0613857 | 2202 | tree callee, arglist, a; |
0a39fd54 | 2203 | int arg_mask, i, type; |
f0613857 | 2204 | bitmap visited; |
2205 | bool ignore; | |
4ee9c684 | 2206 | |
35cc02b5 | 2207 | ignore = TREE_CODE (stmt) != GIMPLE_MODIFY_STMT; |
4ee9c684 | 2208 | |
2209 | /* First try the generic builtin folder. If that succeeds, return the | |
2210 | result directly. */ | |
4a4d48d5 | 2211 | callee = get_callee_fndecl (fn); |
2212 | arglist = TREE_OPERAND (fn, 1); | |
2213 | result = fold_builtin (callee, arglist, ignore); | |
4ee9c684 | 2214 | if (result) |
0a39fd54 | 2215 | { |
2216 | if (ignore) | |
2217 | STRIP_NOPS (result); | |
2218 | return result; | |
2219 | } | |
f0613857 | 2220 | |
2221 | /* Ignore MD builtins. */ | |
f0613857 | 2222 | if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD) |
2223 | return NULL_TREE; | |
4ee9c684 | 2224 | |
2225 | /* If the builtin could not be folded, and it has no argument list, | |
2226 | we're done. */ | |
2227 | if (!arglist) | |
2228 | return NULL_TREE; | |
2229 | ||
2230 | /* Limit the work only for builtins we know how to simplify. */ | |
2231 | switch (DECL_FUNCTION_CODE (callee)) | |
2232 | { | |
2233 | case BUILT_IN_STRLEN: | |
2234 | case BUILT_IN_FPUTS: | |
2235 | case BUILT_IN_FPUTS_UNLOCKED: | |
0a39fd54 | 2236 | arg_mask = 1; |
2237 | type = 0; | |
4ee9c684 | 2238 | break; |
2239 | case BUILT_IN_STRCPY: | |
2240 | case BUILT_IN_STRNCPY: | |
0a39fd54 | 2241 | arg_mask = 2; |
2242 | type = 0; | |
2243 | break; | |
2244 | case BUILT_IN_MEMCPY_CHK: | |
2245 | case BUILT_IN_MEMPCPY_CHK: | |
2246 | case BUILT_IN_MEMMOVE_CHK: | |
2247 | case BUILT_IN_MEMSET_CHK: | |
2248 | case BUILT_IN_STRNCPY_CHK: | |
2249 | arg_mask = 4; | |
2250 | type = 2; | |
2251 | break; | |
2252 | case BUILT_IN_STRCPY_CHK: | |
2253 | case BUILT_IN_STPCPY_CHK: | |
2254 | arg_mask = 2; | |
2255 | type = 1; | |
2256 | break; | |
2257 | case BUILT_IN_SNPRINTF_CHK: | |
2258 | case BUILT_IN_VSNPRINTF_CHK: | |
2259 | arg_mask = 2; | |
2260 | type = 2; | |
4ee9c684 | 2261 | break; |
2262 | default: | |
2263 | return NULL_TREE; | |
2264 | } | |
2265 | ||
2266 | /* Try to use the dataflow information gathered by the CCP process. */ | |
27335ffd | 2267 | visited = BITMAP_ALLOC (NULL); |
4ee9c684 | 2268 | |
0a39fd54 | 2269 | memset (val, 0, sizeof (val)); |
4ee9c684 | 2270 | for (i = 0, a = arglist; |
0a39fd54 | 2271 | arg_mask; |
2272 | i++, arg_mask >>= 1, a = TREE_CHAIN (a)) | |
2273 | if (arg_mask & 1) | |
4ee9c684 | 2274 | { |
2275 | bitmap_clear (visited); | |
0a39fd54 | 2276 | if (!get_maxval_strlen (TREE_VALUE (a), &val[i], visited, type)) |
2277 | val[i] = NULL_TREE; | |
4ee9c684 | 2278 | } |
2279 | ||
27335ffd | 2280 | BITMAP_FREE (visited); |
4ee9c684 | 2281 | |
f0613857 | 2282 | result = NULL_TREE; |
4ee9c684 | 2283 | switch (DECL_FUNCTION_CODE (callee)) |
2284 | { | |
2285 | case BUILT_IN_STRLEN: | |
0a39fd54 | 2286 | if (val[0]) |
4ee9c684 | 2287 | { |
0a39fd54 | 2288 | tree new = fold_convert (TREE_TYPE (fn), val[0]); |
4ee9c684 | 2289 | |
2290 | /* If the result is not a valid gimple value, or not a cast | |
2291 | of a valid gimple value, then we can not use the result. */ | |
2292 | if (is_gimple_val (new) | |
2293 | || (is_gimple_cast (new) | |
2294 | && is_gimple_val (TREE_OPERAND (new, 0)))) | |
2295 | return new; | |
4ee9c684 | 2296 | } |
f0613857 | 2297 | break; |
2298 | ||
4ee9c684 | 2299 | case BUILT_IN_STRCPY: |
0a39fd54 | 2300 | if (val[1] && is_gimple_val (val[1])) |
2301 | result = fold_builtin_strcpy (callee, arglist, val[1]); | |
f0613857 | 2302 | break; |
2303 | ||
4ee9c684 | 2304 | case BUILT_IN_STRNCPY: |
0a39fd54 | 2305 | if (val[1] && is_gimple_val (val[1])) |
2306 | result = fold_builtin_strncpy (callee, arglist, val[1]); | |
f0613857 | 2307 | break; |
2308 | ||
4ee9c684 | 2309 | case BUILT_IN_FPUTS: |
f0613857 | 2310 | result = fold_builtin_fputs (arglist, |
35cc02b5 | 2311 | TREE_CODE (stmt) != GIMPLE_MODIFY_STMT, 0, |
0a39fd54 | 2312 | val[0]); |
f0613857 | 2313 | break; |
2314 | ||
4ee9c684 | 2315 | case BUILT_IN_FPUTS_UNLOCKED: |
f0613857 | 2316 | result = fold_builtin_fputs (arglist, |
35cc02b5 | 2317 | TREE_CODE (stmt) != GIMPLE_MODIFY_STMT, 1, |
0a39fd54 | 2318 | val[0]); |
2319 | break; | |
2320 | ||
2321 | case BUILT_IN_MEMCPY_CHK: | |
2322 | case BUILT_IN_MEMPCPY_CHK: | |
2323 | case BUILT_IN_MEMMOVE_CHK: | |
2324 | case BUILT_IN_MEMSET_CHK: | |
2325 | if (val[2] && is_gimple_val (val[2])) | |
2326 | result = fold_builtin_memory_chk (callee, arglist, val[2], ignore, | |
2327 | DECL_FUNCTION_CODE (callee)); | |
2328 | break; | |
2329 | ||
2330 | case BUILT_IN_STRCPY_CHK: | |
2331 | case BUILT_IN_STPCPY_CHK: | |
2332 | if (val[1] && is_gimple_val (val[1])) | |
2333 | result = fold_builtin_stxcpy_chk (callee, arglist, val[1], ignore, | |
2334 | DECL_FUNCTION_CODE (callee)); | |
2335 | break; | |
2336 | ||
2337 | case BUILT_IN_STRNCPY_CHK: | |
2338 | if (val[2] && is_gimple_val (val[2])) | |
2339 | result = fold_builtin_strncpy_chk (arglist, val[2]); | |
2340 | break; | |
2341 | ||
2342 | case BUILT_IN_SNPRINTF_CHK: | |
2343 | case BUILT_IN_VSNPRINTF_CHK: | |
2344 | if (val[1] && is_gimple_val (val[1])) | |
2345 | result = fold_builtin_snprintf_chk (arglist, val[1], | |
2346 | DECL_FUNCTION_CODE (callee)); | |
f0613857 | 2347 | break; |
4ee9c684 | 2348 | |
2349 | default: | |
8c0963c4 | 2350 | gcc_unreachable (); |
4ee9c684 | 2351 | } |
2352 | ||
f0613857 | 2353 | if (result && ignore) |
db97ad41 | 2354 | result = fold_ignored_result (result); |
f0613857 | 2355 | return result; |
4ee9c684 | 2356 | } |
2357 | ||
2358 | ||
5206b159 | 2359 | /* Fold the statement pointed to by STMT_P. In some cases, this function may |
41511585 | 2360 | replace the whole statement with a new one. Returns true iff folding |
2361 | makes any changes. */ | |
4ee9c684 | 2362 | |
41511585 | 2363 | bool |
2364 | fold_stmt (tree *stmt_p) | |
4ee9c684 | 2365 | { |
41511585 | 2366 | tree rhs, result, stmt; |
0d759d9c | 2367 | struct fold_stmt_r_data fold_stmt_r_data; |
41511585 | 2368 | bool changed = false; |
0d759d9c | 2369 | bool inside_addr_expr = false; |
2370 | ||
2371 | fold_stmt_r_data.changed_p = &changed; | |
2372 | fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr; | |
4ee9c684 | 2373 | |
41511585 | 2374 | stmt = *stmt_p; |
4ee9c684 | 2375 | |
41511585 | 2376 | /* If we replaced constants and the statement makes pointer dereferences, |
2377 | then we may need to fold instances of *&VAR into VAR, etc. */ | |
0d759d9c | 2378 | if (walk_tree (stmt_p, fold_stmt_r, &fold_stmt_r_data, NULL)) |
41511585 | 2379 | { |
2380 | *stmt_p | |
2381 | = build_function_call_expr (implicit_built_in_decls[BUILT_IN_TRAP], | |
2382 | NULL); | |
4ee9c684 | 2383 | return true; |
2384 | } | |
2385 | ||
41511585 | 2386 | rhs = get_rhs (stmt); |
2387 | if (!rhs) | |
2388 | return changed; | |
2389 | result = NULL_TREE; | |
4ee9c684 | 2390 | |
41511585 | 2391 | if (TREE_CODE (rhs) == CALL_EXPR) |
4ee9c684 | 2392 | { |
41511585 | 2393 | tree callee; |
4ee9c684 | 2394 | |
41511585 | 2395 | /* Check for builtins that CCP can handle using information not |
2396 | available in the generic fold routines. */ | |
2397 | callee = get_callee_fndecl (rhs); | |
2398 | if (callee && DECL_BUILT_IN (callee)) | |
2399 | result = ccp_fold_builtin (stmt, rhs); | |
e77b8618 | 2400 | else |
2401 | { | |
2402 | /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve | |
2403 | here are when we've propagated the address of a decl into the | |
2404 | object slot. */ | |
2405 | /* ??? Should perhaps do this in fold proper. However, doing it | |
2406 | there requires that we create a new CALL_EXPR, and that requires | |
2407 | copying EH region info to the new node. Easier to just do it | |
2408 | here where we can just smash the call operand. Also | |
2409 | CALL_EXPR_RETURN_SLOT_OPT needs to be handled correctly and | |
2410 | copied, fold_ternary does not have not information. */ | |
2411 | callee = TREE_OPERAND (rhs, 0); | |
2412 | if (TREE_CODE (callee) == OBJ_TYPE_REF | |
2413 | && lang_hooks.fold_obj_type_ref | |
2414 | && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR | |
2415 | && DECL_P (TREE_OPERAND | |
2416 | (OBJ_TYPE_REF_OBJECT (callee), 0))) | |
2417 | { | |
2418 | tree t; | |
2419 | ||
2420 | /* ??? Caution: Broken ADDR_EXPR semantics means that | |
2421 | looking at the type of the operand of the addr_expr | |
2422 | can yield an array type. See silly exception in | |
2423 | check_pointer_types_r. */ | |
2424 | ||
2425 | t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee))); | |
2426 | t = lang_hooks.fold_obj_type_ref (callee, t); | |
2427 | if (t) | |
2428 | { | |
2429 | TREE_OPERAND (rhs, 0) = t; | |
2430 | changed = true; | |
2431 | } | |
2432 | } | |
2433 | } | |
4ee9c684 | 2434 | } |
2435 | ||
41511585 | 2436 | /* If we couldn't fold the RHS, hand over to the generic fold routines. */ |
2437 | if (result == NULL_TREE) | |
2438 | result = fold (rhs); | |
4ee9c684 | 2439 | |
41511585 | 2440 | /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that |
2441 | may have been added by fold, and "useless" type conversions that might | |
2442 | now be apparent due to propagation. */ | |
2443 | STRIP_USELESS_TYPE_CONVERSION (result); | |
2444 | ||
2445 | if (result != rhs) | |
2446 | changed |= set_rhs (stmt_p, result); | |
2447 | ||
2448 | return changed; | |
4ee9c684 | 2449 | } |
2450 | ||
8171a1dd | 2451 | /* Perform the minimal folding on statement STMT. Only operations like |
2452 | *&x created by constant propagation are handled. The statement cannot | |
2453 | be replaced with a new one. */ | |
2454 | ||
2455 | bool | |
2456 | fold_stmt_inplace (tree stmt) | |
2457 | { | |
2458 | tree old_stmt = stmt, rhs, new_rhs; | |
0d759d9c | 2459 | struct fold_stmt_r_data fold_stmt_r_data; |
8171a1dd | 2460 | bool changed = false; |
0d759d9c | 2461 | bool inside_addr_expr = false; |
2462 | ||
2463 | fold_stmt_r_data.changed_p = &changed; | |
2464 | fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr; | |
8171a1dd | 2465 | |
0d759d9c | 2466 | walk_tree (&stmt, fold_stmt_r, &fold_stmt_r_data, NULL); |
8171a1dd | 2467 | gcc_assert (stmt == old_stmt); |
2468 | ||
2469 | rhs = get_rhs (stmt); | |
2470 | if (!rhs || rhs == stmt) | |
2471 | return changed; | |
2472 | ||
2473 | new_rhs = fold (rhs); | |
ff09445d | 2474 | STRIP_USELESS_TYPE_CONVERSION (new_rhs); |
8171a1dd | 2475 | if (new_rhs == rhs) |
2476 | return changed; | |
2477 | ||
2478 | changed |= set_rhs (&stmt, new_rhs); | |
2479 | gcc_assert (stmt == old_stmt); | |
2480 | ||
2481 | return changed; | |
2482 | } | |
4ee9c684 | 2483 | \f |
909e5ecb | 2484 | /* Convert EXPR into a GIMPLE value suitable for substitution on the |
2485 | RHS of an assignment. Insert the necessary statements before | |
a280136a | 2486 | iterator *SI_P. |
2487 | When IGNORE is set, don't worry about the return value. */ | |
909e5ecb | 2488 | |
2489 | static tree | |
a280136a | 2490 | convert_to_gimple_builtin (block_stmt_iterator *si_p, tree expr, bool ignore) |
909e5ecb | 2491 | { |
2492 | tree_stmt_iterator ti; | |
2493 | tree stmt = bsi_stmt (*si_p); | |
2494 | tree tmp, stmts = NULL; | |
2495 | ||
2496 | push_gimplify_context (); | |
a280136a | 2497 | if (ignore) |
2498 | { | |
2499 | tmp = build_empty_stmt (); | |
2500 | gimplify_and_add (expr, &stmts); | |
2501 | } | |
2502 | else | |
2503 | tmp = get_initialized_tmp_var (expr, &stmts, NULL); | |
909e5ecb | 2504 | pop_gimplify_context (NULL); |
2505 | ||
b66731e8 | 2506 | if (EXPR_HAS_LOCATION (stmt)) |
2507 | annotate_all_with_locus (&stmts, EXPR_LOCATION (stmt)); | |
2508 | ||
909e5ecb | 2509 | /* The replacement can expose previously unreferenced variables. */ |
2510 | for (ti = tsi_start (stmts); !tsi_end_p (ti); tsi_next (&ti)) | |
2511 | { | |
b66731e8 | 2512 | tree new_stmt = tsi_stmt (ti); |
909e5ecb | 2513 | find_new_referenced_vars (tsi_stmt_ptr (ti)); |
b66731e8 | 2514 | bsi_insert_before (si_p, new_stmt, BSI_NEW_STMT); |
2515 | mark_new_vars_to_rename (bsi_stmt (*si_p)); | |
2516 | bsi_next (si_p); | |
909e5ecb | 2517 | } |
2518 | ||
909e5ecb | 2519 | return tmp; |
2520 | } | |
2521 | ||
2522 | ||
4ee9c684 | 2523 | /* A simple pass that attempts to fold all builtin functions. This pass |
2524 | is run after we've propagated as many constants as we can. */ | |
2525 | ||
2a1990e9 | 2526 | static unsigned int |
4ee9c684 | 2527 | execute_fold_all_builtins (void) |
2528 | { | |
b36237eb | 2529 | bool cfg_changed = false; |
4ee9c684 | 2530 | basic_block bb; |
2531 | FOR_EACH_BB (bb) | |
2532 | { | |
2533 | block_stmt_iterator i; | |
0a39fd54 | 2534 | for (i = bsi_start (bb); !bsi_end_p (i); ) |
4ee9c684 | 2535 | { |
2536 | tree *stmtp = bsi_stmt_ptr (i); | |
4c27dd45 | 2537 | tree old_stmt = *stmtp; |
4ee9c684 | 2538 | tree call = get_rhs (*stmtp); |
2539 | tree callee, result; | |
0a39fd54 | 2540 | enum built_in_function fcode; |
4ee9c684 | 2541 | |
2542 | if (!call || TREE_CODE (call) != CALL_EXPR) | |
0a39fd54 | 2543 | { |
2544 | bsi_next (&i); | |
2545 | continue; | |
2546 | } | |
4ee9c684 | 2547 | callee = get_callee_fndecl (call); |
2548 | if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL) | |
0a39fd54 | 2549 | { |
2550 | bsi_next (&i); | |
2551 | continue; | |
2552 | } | |
2553 | fcode = DECL_FUNCTION_CODE (callee); | |
4ee9c684 | 2554 | |
2555 | result = ccp_fold_builtin (*stmtp, call); | |
2556 | if (!result) | |
2557 | switch (DECL_FUNCTION_CODE (callee)) | |
2558 | { | |
2559 | case BUILT_IN_CONSTANT_P: | |
2560 | /* Resolve __builtin_constant_p. If it hasn't been | |
2561 | folded to integer_one_node by now, it's fairly | |
2562 | certain that the value simply isn't constant. */ | |
2563 | result = integer_zero_node; | |
2564 | break; | |
2565 | ||
2566 | default: | |
0a39fd54 | 2567 | bsi_next (&i); |
4ee9c684 | 2568 | continue; |
2569 | } | |
2570 | ||
2571 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2572 | { | |
2573 | fprintf (dump_file, "Simplified\n "); | |
2574 | print_generic_stmt (dump_file, *stmtp, dump_flags); | |
2575 | } | |
2576 | ||
909e5ecb | 2577 | if (!set_rhs (stmtp, result)) |
2578 | { | |
a280136a | 2579 | result = convert_to_gimple_builtin (&i, result, |
2580 | TREE_CODE (old_stmt) | |
35cc02b5 | 2581 | != GIMPLE_MODIFY_STMT); |
876760f6 | 2582 | if (result) |
2583 | { | |
2584 | bool ok = set_rhs (stmtp, result); | |
2585 | ||
2586 | gcc_assert (ok); | |
2587 | } | |
909e5ecb | 2588 | } |
ca92b9d2 | 2589 | mark_new_vars_to_rename (*stmtp); |
4c27dd45 | 2590 | if (maybe_clean_or_replace_eh_stmt (old_stmt, *stmtp) |
b36237eb | 2591 | && tree_purge_dead_eh_edges (bb)) |
2592 | cfg_changed = true; | |
4ee9c684 | 2593 | |
2594 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2595 | { | |
2596 | fprintf (dump_file, "to\n "); | |
2597 | print_generic_stmt (dump_file, *stmtp, dump_flags); | |
2598 | fprintf (dump_file, "\n"); | |
2599 | } | |
0a39fd54 | 2600 | |
2601 | /* Retry the same statement if it changed into another | |
2602 | builtin, there might be new opportunities now. */ | |
2603 | call = get_rhs (*stmtp); | |
2604 | if (!call || TREE_CODE (call) != CALL_EXPR) | |
2605 | { | |
2606 | bsi_next (&i); | |
2607 | continue; | |
2608 | } | |
2609 | callee = get_callee_fndecl (call); | |
2610 | if (!callee | |
2611 | || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL | |
2612 | || DECL_FUNCTION_CODE (callee) == fcode) | |
2613 | bsi_next (&i); | |
4ee9c684 | 2614 | } |
2615 | } | |
b36237eb | 2616 | |
2617 | /* Delete unreachable blocks. */ | |
2618 | if (cfg_changed) | |
2619 | cleanup_tree_cfg (); | |
2a1990e9 | 2620 | return 0; |
4ee9c684 | 2621 | } |
2622 | ||
41511585 | 2623 | |
4ee9c684 | 2624 | struct tree_opt_pass pass_fold_builtins = |
2625 | { | |
2626 | "fab", /* name */ | |
2627 | NULL, /* gate */ | |
2628 | execute_fold_all_builtins, /* execute */ | |
2629 | NULL, /* sub */ | |
2630 | NULL, /* next */ | |
2631 | 0, /* static_pass_number */ | |
2632 | 0, /* tv_id */ | |
f45a1ca1 | 2633 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ |
4ee9c684 | 2634 | 0, /* properties_provided */ |
2635 | 0, /* properties_destroyed */ | |
2636 | 0, /* todo_flags_start */ | |
909e5ecb | 2637 | TODO_dump_func |
2638 | | TODO_verify_ssa | |
88dbf20f | 2639 | | TODO_update_ssa, /* todo_flags_finish */ |
0f9005dd | 2640 | 0 /* letter */ |
4ee9c684 | 2641 | }; |