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4ee9c684 | 1 | /* Conditional constant propagation pass for the GNU compiler. |
cfaf579d | 2 | Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 |
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 | |
8c4c00c1 | 11 | Free Software Foundation; either version 3, or (at your option) any |
4ee9c684 | 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 | |
8c4c00c1 | 20 | along with GCC; see the file COPYING3. If not see |
21 | <http://www.gnu.org/licenses/>. */ | |
4ee9c684 | 22 | |
88dbf20f | 23 | /* Conditional constant propagation (CCP) is based on the SSA |
24 | propagation engine (tree-ssa-propagate.c). Constant assignments of | |
25 | the form VAR = CST are propagated from the assignments into uses of | |
26 | VAR, which in turn may generate new constants. The simulation uses | |
27 | a four level lattice to keep track of constant values associated | |
28 | with SSA names. Given an SSA name V_i, it may take one of the | |
29 | following values: | |
30 | ||
bfa30570 | 31 | UNINITIALIZED -> the initial state of the value. This value |
32 | is replaced with a correct initial value | |
33 | the first time the value is used, so the | |
34 | rest of the pass does not need to care about | |
35 | it. Using this value simplifies initialization | |
36 | of the pass, and prevents us from needlessly | |
37 | scanning statements that are never reached. | |
88dbf20f | 38 | |
39 | UNDEFINED -> V_i is a local variable whose definition | |
40 | has not been processed yet. Therefore we | |
41 | don't yet know if its value is a constant | |
42 | or not. | |
43 | ||
44 | CONSTANT -> V_i has been found to hold a constant | |
45 | value C. | |
46 | ||
47 | VARYING -> V_i cannot take a constant value, or if it | |
48 | does, it is not possible to determine it | |
49 | at compile time. | |
50 | ||
51 | The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node: | |
52 | ||
53 | 1- In ccp_visit_stmt, we are interested in assignments whose RHS | |
54 | evaluates into a constant and conditional jumps whose predicate | |
55 | evaluates into a boolean true or false. When an assignment of | |
56 | the form V_i = CONST is found, V_i's lattice value is set to | |
57 | CONSTANT and CONST is associated with it. This causes the | |
58 | propagation engine to add all the SSA edges coming out the | |
59 | assignment into the worklists, so that statements that use V_i | |
60 | can be visited. | |
61 | ||
62 | If the statement is a conditional with a constant predicate, we | |
63 | mark the outgoing edges as executable or not executable | |
64 | depending on the predicate's value. This is then used when | |
65 | visiting PHI nodes to know when a PHI argument can be ignored. | |
66 | ||
67 | ||
68 | 2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the | |
69 | same constant C, then the LHS of the PHI is set to C. This | |
70 | evaluation is known as the "meet operation". Since one of the | |
71 | goals of this evaluation is to optimistically return constant | |
72 | values as often as possible, it uses two main short cuts: | |
73 | ||
74 | - If an argument is flowing in through a non-executable edge, it | |
75 | is ignored. This is useful in cases like this: | |
76 | ||
77 | if (PRED) | |
78 | a_9 = 3; | |
79 | else | |
80 | a_10 = 100; | |
81 | a_11 = PHI (a_9, a_10) | |
82 | ||
83 | If PRED is known to always evaluate to false, then we can | |
84 | assume that a_11 will always take its value from a_10, meaning | |
85 | that instead of consider it VARYING (a_9 and a_10 have | |
86 | different values), we can consider it CONSTANT 100. | |
87 | ||
88 | - If an argument has an UNDEFINED value, then it does not affect | |
89 | the outcome of the meet operation. If a variable V_i has an | |
90 | UNDEFINED value, it means that either its defining statement | |
91 | hasn't been visited yet or V_i has no defining statement, in | |
92 | which case the original symbol 'V' is being used | |
93 | uninitialized. Since 'V' is a local variable, the compiler | |
94 | may assume any initial value for it. | |
95 | ||
96 | ||
97 | After propagation, every variable V_i that ends up with a lattice | |
98 | value of CONSTANT will have the associated constant value in the | |
99 | array CONST_VAL[i].VALUE. That is fed into substitute_and_fold for | |
100 | final substitution and folding. | |
101 | ||
102 | ||
103 | Constant propagation in stores and loads (STORE-CCP) | |
104 | ---------------------------------------------------- | |
105 | ||
106 | While CCP has all the logic to propagate constants in GIMPLE | |
107 | registers, it is missing the ability to associate constants with | |
108 | stores and loads (i.e., pointer dereferences, structures and | |
109 | global/aliased variables). We don't keep loads and stores in | |
110 | SSA, but we do build a factored use-def web for them (in the | |
111 | virtual operands). | |
112 | ||
113 | For instance, consider the following code fragment: | |
114 | ||
115 | struct A a; | |
116 | const int B = 42; | |
117 | ||
118 | void foo (int i) | |
119 | { | |
120 | if (i > 10) | |
121 | a.a = 42; | |
122 | else | |
123 | { | |
124 | a.b = 21; | |
125 | a.a = a.b + 21; | |
126 | } | |
127 | ||
128 | if (a.a != B) | |
129 | never_executed (); | |
130 | } | |
131 | ||
132 | We should be able to deduce that the predicate 'a.a != B' is always | |
133 | false. To achieve this, we associate constant values to the SSA | |
4fb5e5ca | 134 | names in the VDEF operands for each store. Additionally, |
135 | since we also glob partial loads/stores with the base symbol, we | |
136 | also keep track of the memory reference where the constant value | |
137 | was stored (in the MEM_REF field of PROP_VALUE_T). For instance, | |
88dbf20f | 138 | |
4fb5e5ca | 139 | # a_5 = VDEF <a_4> |
88dbf20f | 140 | a.a = 2; |
141 | ||
142 | # VUSE <a_5> | |
143 | x_3 = a.b; | |
144 | ||
145 | In the example above, CCP will associate value '2' with 'a_5', but | |
146 | it would be wrong to replace the load from 'a.b' with '2', because | |
147 | '2' had been stored into a.a. | |
148 | ||
bfa30570 | 149 | Note that the initial value of virtual operands is VARYING, not |
150 | UNDEFINED. Consider, for instance global variables: | |
88dbf20f | 151 | |
152 | int A; | |
153 | ||
154 | foo (int i) | |
155 | { | |
156 | if (i_3 > 10) | |
157 | A_4 = 3; | |
158 | # A_5 = PHI (A_4, A_2); | |
159 | ||
160 | # VUSE <A_5> | |
161 | A.0_6 = A; | |
162 | ||
163 | return A.0_6; | |
164 | } | |
165 | ||
166 | The value of A_2 cannot be assumed to be UNDEFINED, as it may have | |
167 | been defined outside of foo. If we were to assume it UNDEFINED, we | |
bfa30570 | 168 | would erroneously optimize the above into 'return 3;'. |
88dbf20f | 169 | |
170 | Though STORE-CCP is not too expensive, it does have to do more work | |
171 | than regular CCP, so it is only enabled at -O2. Both regular CCP | |
172 | and STORE-CCP use the exact same algorithm. The only distinction | |
173 | is that when doing STORE-CCP, the boolean variable DO_STORE_CCP is | |
174 | set to true. This affects the evaluation of statements and PHI | |
175 | nodes. | |
4ee9c684 | 176 | |
177 | References: | |
178 | ||
179 | Constant propagation with conditional branches, | |
180 | Wegman and Zadeck, ACM TOPLAS 13(2):181-210. | |
181 | ||
182 | Building an Optimizing Compiler, | |
183 | Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9. | |
184 | ||
185 | Advanced Compiler Design and Implementation, | |
186 | Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */ | |
187 | ||
188 | #include "config.h" | |
189 | #include "system.h" | |
190 | #include "coretypes.h" | |
191 | #include "tm.h" | |
4ee9c684 | 192 | #include "tree.h" |
41511585 | 193 | #include "flags.h" |
4ee9c684 | 194 | #include "rtl.h" |
195 | #include "tm_p.h" | |
41511585 | 196 | #include "ggc.h" |
4ee9c684 | 197 | #include "basic-block.h" |
41511585 | 198 | #include "output.h" |
41511585 | 199 | #include "expr.h" |
200 | #include "function.h" | |
4ee9c684 | 201 | #include "diagnostic.h" |
41511585 | 202 | #include "timevar.h" |
4ee9c684 | 203 | #include "tree-dump.h" |
41511585 | 204 | #include "tree-flow.h" |
4ee9c684 | 205 | #include "tree-pass.h" |
41511585 | 206 | #include "tree-ssa-propagate.h" |
5a4b7e1e | 207 | #include "value-prof.h" |
41511585 | 208 | #include "langhooks.h" |
8782adcf | 209 | #include "target.h" |
add6ee5e | 210 | #include "toplev.h" |
43fb76c1 | 211 | #include "dbgcnt.h" |
4ee9c684 | 212 | |
213 | ||
214 | /* Possible lattice values. */ | |
215 | typedef enum | |
216 | { | |
bfa30570 | 217 | UNINITIALIZED, |
4ee9c684 | 218 | UNDEFINED, |
219 | CONSTANT, | |
220 | VARYING | |
88dbf20f | 221 | } ccp_lattice_t; |
4ee9c684 | 222 | |
88dbf20f | 223 | /* Array of propagated constant values. After propagation, |
224 | CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I). If | |
225 | the constant is held in an SSA name representing a memory store | |
4fb5e5ca | 226 | (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual |
227 | memory reference used to store (i.e., the LHS of the assignment | |
228 | doing the store). */ | |
20140406 | 229 | static prop_value_t *const_val; |
4ee9c684 | 230 | |
88dbf20f | 231 | /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX. */ |
01406fc0 | 232 | |
233 | static void | |
88dbf20f | 234 | dump_lattice_value (FILE *outf, const char *prefix, prop_value_t val) |
01406fc0 | 235 | { |
41511585 | 236 | switch (val.lattice_val) |
01406fc0 | 237 | { |
88dbf20f | 238 | case UNINITIALIZED: |
239 | fprintf (outf, "%sUNINITIALIZED", prefix); | |
240 | break; | |
41511585 | 241 | case UNDEFINED: |
242 | fprintf (outf, "%sUNDEFINED", prefix); | |
243 | break; | |
244 | case VARYING: | |
245 | fprintf (outf, "%sVARYING", prefix); | |
246 | break; | |
41511585 | 247 | case CONSTANT: |
248 | fprintf (outf, "%sCONSTANT ", prefix); | |
88dbf20f | 249 | print_generic_expr (outf, val.value, dump_flags); |
41511585 | 250 | break; |
251 | default: | |
8c0963c4 | 252 | gcc_unreachable (); |
41511585 | 253 | } |
01406fc0 | 254 | } |
4ee9c684 | 255 | |
4ee9c684 | 256 | |
88dbf20f | 257 | /* Print lattice value VAL to stderr. */ |
258 | ||
259 | void debug_lattice_value (prop_value_t val); | |
260 | ||
261 | void | |
262 | debug_lattice_value (prop_value_t val) | |
263 | { | |
264 | dump_lattice_value (stderr, "", val); | |
265 | fprintf (stderr, "\n"); | |
266 | } | |
4ee9c684 | 267 | |
4ee9c684 | 268 | |
75a70cf9 | 269 | |
aecfc21d | 270 | /* If SYM is a constant variable with known value, return the value. |
271 | NULL_TREE is returned otherwise. */ | |
272 | ||
e004838d | 273 | tree |
aecfc21d | 274 | get_symbol_constant_value (tree sym) |
275 | { | |
276 | if (TREE_STATIC (sym) | |
dd277d48 | 277 | && TREE_READONLY (sym)) |
aecfc21d | 278 | { |
279 | tree val = DECL_INITIAL (sym); | |
590d65aa | 280 | if (val) |
281 | { | |
282 | STRIP_USELESS_TYPE_CONVERSION (val); | |
283 | if (is_gimple_min_invariant (val)) | |
284 | return val; | |
285 | } | |
6e6e51e5 | 286 | /* Variables declared 'const' without an initializer |
f0b5f617 | 287 | have zero as the initializer if they may not be |
e004838d | 288 | overridden at link or run time. */ |
6e6e51e5 | 289 | if (!val |
807bf718 | 290 | && !DECL_EXTERNAL (sym) |
e004838d | 291 | && targetm.binds_local_p (sym) |
6e6e51e5 | 292 | && (INTEGRAL_TYPE_P (TREE_TYPE (sym)) |
293 | || SCALAR_FLOAT_TYPE_P (TREE_TYPE (sym)))) | |
807bf718 | 294 | return fold_convert (TREE_TYPE (sym), integer_zero_node); |
aecfc21d | 295 | } |
296 | ||
297 | return NULL_TREE; | |
298 | } | |
d03bd588 | 299 | |
88dbf20f | 300 | /* Compute a default value for variable VAR and store it in the |
301 | CONST_VAL array. The following rules are used to get default | |
302 | values: | |
01406fc0 | 303 | |
88dbf20f | 304 | 1- Global and static variables that are declared constant are |
305 | considered CONSTANT. | |
306 | ||
307 | 2- Any other value is considered UNDEFINED. This is useful when | |
41511585 | 308 | considering PHI nodes. PHI arguments that are undefined do not |
309 | change the constant value of the PHI node, which allows for more | |
88dbf20f | 310 | constants to be propagated. |
4ee9c684 | 311 | |
8883e700 | 312 | 3- Variables defined by statements other than assignments and PHI |
88dbf20f | 313 | nodes are considered VARYING. |
4ee9c684 | 314 | |
8883e700 | 315 | 4- Initial values of variables that are not GIMPLE registers are |
bfa30570 | 316 | considered VARYING. */ |
4ee9c684 | 317 | |
88dbf20f | 318 | static prop_value_t |
319 | get_default_value (tree var) | |
320 | { | |
321 | tree sym = SSA_NAME_VAR (var); | |
61207d43 | 322 | prop_value_t val = { UNINITIALIZED, NULL_TREE }; |
8edeb88b | 323 | gimple stmt; |
324 | ||
325 | stmt = SSA_NAME_DEF_STMT (var); | |
326 | ||
327 | if (gimple_nop_p (stmt)) | |
4ee9c684 | 328 | { |
8edeb88b | 329 | /* Variables defined by an empty statement are those used |
330 | before being initialized. If VAR is a local variable, we | |
331 | can assume initially that it is UNDEFINED, otherwise we must | |
332 | consider it VARYING. */ | |
333 | if (is_gimple_reg (sym) && TREE_CODE (sym) != PARM_DECL) | |
334 | val.lattice_val = UNDEFINED; | |
335 | else | |
336 | val.lattice_val = VARYING; | |
4ee9c684 | 337 | } |
8edeb88b | 338 | else if (is_gimple_assign (stmt) |
339 | /* Value-returning GIMPLE_CALL statements assign to | |
340 | a variable, and are treated similarly to GIMPLE_ASSIGN. */ | |
341 | || (is_gimple_call (stmt) | |
342 | && gimple_call_lhs (stmt) != NULL_TREE) | |
343 | || gimple_code (stmt) == GIMPLE_PHI) | |
41511585 | 344 | { |
8edeb88b | 345 | tree cst; |
346 | if (gimple_assign_single_p (stmt) | |
347 | && DECL_P (gimple_assign_rhs1 (stmt)) | |
348 | && (cst = get_symbol_constant_value (gimple_assign_rhs1 (stmt)))) | |
88dbf20f | 349 | { |
8edeb88b | 350 | val.lattice_val = CONSTANT; |
351 | val.value = cst; | |
88dbf20f | 352 | } |
353 | else | |
8edeb88b | 354 | /* Any other variable defined by an assignment or a PHI node |
355 | is considered UNDEFINED. */ | |
356 | val.lattice_val = UNDEFINED; | |
357 | } | |
358 | else | |
359 | { | |
360 | /* Otherwise, VAR will never take on a constant value. */ | |
361 | val.lattice_val = VARYING; | |
41511585 | 362 | } |
4ee9c684 | 363 | |
41511585 | 364 | return val; |
365 | } | |
4ee9c684 | 366 | |
4ee9c684 | 367 | |
bfa30570 | 368 | /* Get the constant value associated with variable VAR. */ |
4ee9c684 | 369 | |
bfa30570 | 370 | static inline prop_value_t * |
371 | get_value (tree var) | |
88dbf20f | 372 | { |
e004838d | 373 | prop_value_t *val; |
bfa30570 | 374 | |
e004838d | 375 | if (const_val == NULL) |
376 | return NULL; | |
377 | ||
378 | val = &const_val[SSA_NAME_VERSION (var)]; | |
bfa30570 | 379 | if (val->lattice_val == UNINITIALIZED) |
4ee9c684 | 380 | *val = get_default_value (var); |
381 | ||
382 | return val; | |
383 | } | |
384 | ||
bfa30570 | 385 | /* Sets the value associated with VAR to VARYING. */ |
386 | ||
387 | static inline void | |
388 | set_value_varying (tree var) | |
389 | { | |
390 | prop_value_t *val = &const_val[SSA_NAME_VERSION (var)]; | |
391 | ||
392 | val->lattice_val = VARYING; | |
393 | val->value = NULL_TREE; | |
bfa30570 | 394 | } |
4ee9c684 | 395 | |
b31eb493 | 396 | /* For float types, modify the value of VAL to make ccp work correctly |
397 | for non-standard values (-0, NaN): | |
398 | ||
399 | If HONOR_SIGNED_ZEROS is false, and VAL = -0, we canonicalize it to 0. | |
400 | If HONOR_NANS is false, and VAL is NaN, we canonicalize it to UNDEFINED. | |
401 | This is to fix the following problem (see PR 29921): Suppose we have | |
402 | ||
403 | x = 0.0 * y | |
404 | ||
405 | and we set value of y to NaN. This causes value of x to be set to NaN. | |
406 | When we later determine that y is in fact VARYING, fold uses the fact | |
407 | that HONOR_NANS is false, and we try to change the value of x to 0, | |
408 | causing an ICE. With HONOR_NANS being false, the real appearance of | |
409 | NaN would cause undefined behavior, though, so claiming that y (and x) | |
410 | are UNDEFINED initially is correct. */ | |
411 | ||
412 | static void | |
413 | canonicalize_float_value (prop_value_t *val) | |
414 | { | |
415 | enum machine_mode mode; | |
416 | tree type; | |
417 | REAL_VALUE_TYPE d; | |
418 | ||
419 | if (val->lattice_val != CONSTANT | |
420 | || TREE_CODE (val->value) != REAL_CST) | |
421 | return; | |
422 | ||
423 | d = TREE_REAL_CST (val->value); | |
424 | type = TREE_TYPE (val->value); | |
425 | mode = TYPE_MODE (type); | |
426 | ||
427 | if (!HONOR_SIGNED_ZEROS (mode) | |
428 | && REAL_VALUE_MINUS_ZERO (d)) | |
429 | { | |
430 | val->value = build_real (type, dconst0); | |
431 | return; | |
432 | } | |
433 | ||
434 | if (!HONOR_NANS (mode) | |
435 | && REAL_VALUE_ISNAN (d)) | |
436 | { | |
437 | val->lattice_val = UNDEFINED; | |
438 | val->value = NULL; | |
b31eb493 | 439 | return; |
440 | } | |
441 | } | |
442 | ||
88dbf20f | 443 | /* Set the value for variable VAR to NEW_VAL. Return true if the new |
444 | value is different from VAR's previous value. */ | |
4ee9c684 | 445 | |
41511585 | 446 | static bool |
88dbf20f | 447 | set_lattice_value (tree var, prop_value_t new_val) |
4ee9c684 | 448 | { |
bfa30570 | 449 | prop_value_t *old_val = get_value (var); |
88dbf20f | 450 | |
b31eb493 | 451 | canonicalize_float_value (&new_val); |
452 | ||
88dbf20f | 453 | /* Lattice transitions must always be monotonically increasing in |
bfa30570 | 454 | value. If *OLD_VAL and NEW_VAL are the same, return false to |
455 | inform the caller that this was a non-transition. */ | |
456 | ||
aecfc21d | 457 | gcc_assert (old_val->lattice_val < new_val.lattice_val |
88dbf20f | 458 | || (old_val->lattice_val == new_val.lattice_val |
aecfc21d | 459 | && ((!old_val->value && !new_val.value) |
61207d43 | 460 | || operand_equal_p (old_val->value, new_val.value, 0)))); |
88dbf20f | 461 | |
462 | if (old_val->lattice_val != new_val.lattice_val) | |
4ee9c684 | 463 | { |
41511585 | 464 | if (dump_file && (dump_flags & TDF_DETAILS)) |
465 | { | |
88dbf20f | 466 | dump_lattice_value (dump_file, "Lattice value changed to ", new_val); |
bfa30570 | 467 | fprintf (dump_file, ". Adding SSA edges to worklist.\n"); |
41511585 | 468 | } |
469 | ||
88dbf20f | 470 | *old_val = new_val; |
471 | ||
bfa30570 | 472 | gcc_assert (new_val.lattice_val != UNDEFINED); |
473 | return true; | |
4ee9c684 | 474 | } |
41511585 | 475 | |
476 | return false; | |
4ee9c684 | 477 | } |
478 | ||
479 | ||
88dbf20f | 480 | /* Return the likely CCP lattice value for STMT. |
4ee9c684 | 481 | |
41511585 | 482 | If STMT has no operands, then return CONSTANT. |
4ee9c684 | 483 | |
d61b9af3 | 484 | Else if undefinedness of operands of STMT cause its value to be |
485 | undefined, then return UNDEFINED. | |
4ee9c684 | 486 | |
41511585 | 487 | Else if any operands of STMT are constants, then return CONSTANT. |
4ee9c684 | 488 | |
41511585 | 489 | Else return VARYING. */ |
4ee9c684 | 490 | |
88dbf20f | 491 | static ccp_lattice_t |
75a70cf9 | 492 | likely_value (gimple stmt) |
41511585 | 493 | { |
d61b9af3 | 494 | bool has_constant_operand, has_undefined_operand, all_undefined_operands; |
41511585 | 495 | tree use; |
496 | ssa_op_iter iter; | |
8edeb88b | 497 | unsigned i; |
4ee9c684 | 498 | |
590c3166 | 499 | enum gimple_code code = gimple_code (stmt); |
75a70cf9 | 500 | |
501 | /* This function appears to be called only for assignments, calls, | |
502 | conditionals, and switches, due to the logic in visit_stmt. */ | |
503 | gcc_assert (code == GIMPLE_ASSIGN | |
504 | || code == GIMPLE_CALL | |
505 | || code == GIMPLE_COND | |
506 | || code == GIMPLE_SWITCH); | |
88dbf20f | 507 | |
508 | /* If the statement has volatile operands, it won't fold to a | |
509 | constant value. */ | |
75a70cf9 | 510 | if (gimple_has_volatile_ops (stmt)) |
88dbf20f | 511 | return VARYING; |
512 | ||
75a70cf9 | 513 | /* Arrive here for more complex cases. */ |
bfa30570 | 514 | has_constant_operand = false; |
d61b9af3 | 515 | has_undefined_operand = false; |
516 | all_undefined_operands = true; | |
8edeb88b | 517 | FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE) |
41511585 | 518 | { |
bfa30570 | 519 | prop_value_t *val = get_value (use); |
41511585 | 520 | |
bfa30570 | 521 | if (val->lattice_val == UNDEFINED) |
d61b9af3 | 522 | has_undefined_operand = true; |
523 | else | |
524 | all_undefined_operands = false; | |
88dbf20f | 525 | |
41511585 | 526 | if (val->lattice_val == CONSTANT) |
bfa30570 | 527 | has_constant_operand = true; |
4ee9c684 | 528 | } |
41511585 | 529 | |
dd277d48 | 530 | /* There may be constants in regular rhs operands. For calls we |
531 | have to ignore lhs, fndecl and static chain, otherwise only | |
532 | the lhs. */ | |
533 | for (i = (is_gimple_call (stmt) ? 2 : 0) + gimple_has_lhs (stmt); | |
8edeb88b | 534 | i < gimple_num_ops (stmt); ++i) |
535 | { | |
536 | tree op = gimple_op (stmt, i); | |
537 | if (!op || TREE_CODE (op) == SSA_NAME) | |
538 | continue; | |
539 | if (is_gimple_min_invariant (op)) | |
540 | has_constant_operand = true; | |
541 | } | |
542 | ||
d61b9af3 | 543 | /* If the operation combines operands like COMPLEX_EXPR make sure to |
544 | not mark the result UNDEFINED if only one part of the result is | |
545 | undefined. */ | |
75a70cf9 | 546 | if (has_undefined_operand && all_undefined_operands) |
d61b9af3 | 547 | return UNDEFINED; |
75a70cf9 | 548 | else if (code == GIMPLE_ASSIGN && has_undefined_operand) |
d61b9af3 | 549 | { |
75a70cf9 | 550 | switch (gimple_assign_rhs_code (stmt)) |
d61b9af3 | 551 | { |
552 | /* Unary operators are handled with all_undefined_operands. */ | |
553 | case PLUS_EXPR: | |
554 | case MINUS_EXPR: | |
d61b9af3 | 555 | case POINTER_PLUS_EXPR: |
d61b9af3 | 556 | /* Not MIN_EXPR, MAX_EXPR. One VARYING operand may be selected. |
557 | Not bitwise operators, one VARYING operand may specify the | |
558 | result completely. Not logical operators for the same reason. | |
05a936a0 | 559 | Not COMPLEX_EXPR as one VARYING operand makes the result partly |
560 | not UNDEFINED. Not *DIV_EXPR, comparisons and shifts because | |
561 | the undefined operand may be promoted. */ | |
d61b9af3 | 562 | return UNDEFINED; |
563 | ||
564 | default: | |
565 | ; | |
566 | } | |
567 | } | |
568 | /* If there was an UNDEFINED operand but the result may be not UNDEFINED | |
569 | fall back to VARYING even if there were CONSTANT operands. */ | |
570 | if (has_undefined_operand) | |
571 | return VARYING; | |
572 | ||
8edeb88b | 573 | /* We do not consider virtual operands here -- load from read-only |
574 | memory may have only VARYING virtual operands, but still be | |
575 | constant. */ | |
bfa30570 | 576 | if (has_constant_operand |
8edeb88b | 577 | || gimple_references_memory_p (stmt)) |
88dbf20f | 578 | return CONSTANT; |
579 | ||
bfa30570 | 580 | return VARYING; |
4ee9c684 | 581 | } |
582 | ||
bfa30570 | 583 | /* Returns true if STMT cannot be constant. */ |
584 | ||
585 | static bool | |
75a70cf9 | 586 | surely_varying_stmt_p (gimple stmt) |
bfa30570 | 587 | { |
588 | /* If the statement has operands that we cannot handle, it cannot be | |
589 | constant. */ | |
75a70cf9 | 590 | if (gimple_has_volatile_ops (stmt)) |
bfa30570 | 591 | return true; |
592 | ||
f257af64 | 593 | /* If it is a call and does not return a value or is not a |
594 | builtin and not an indirect call, it is varying. */ | |
75a70cf9 | 595 | if (is_gimple_call (stmt)) |
f257af64 | 596 | { |
597 | tree fndecl; | |
598 | if (!gimple_call_lhs (stmt) | |
599 | || ((fndecl = gimple_call_fndecl (stmt)) != NULL_TREE | |
5768aeb3 | 600 | && !DECL_BUILT_IN (fndecl))) |
f257af64 | 601 | return true; |
602 | } | |
bfa30570 | 603 | |
8edeb88b | 604 | /* Any other store operation is not interesting. */ |
dd277d48 | 605 | else if (gimple_vdef (stmt)) |
8edeb88b | 606 | return true; |
607 | ||
bfa30570 | 608 | /* Anything other than assignments and conditional jumps are not |
609 | interesting for CCP. */ | |
75a70cf9 | 610 | if (gimple_code (stmt) != GIMPLE_ASSIGN |
f257af64 | 611 | && gimple_code (stmt) != GIMPLE_COND |
612 | && gimple_code (stmt) != GIMPLE_SWITCH | |
613 | && gimple_code (stmt) != GIMPLE_CALL) | |
bfa30570 | 614 | return true; |
615 | ||
616 | return false; | |
617 | } | |
4ee9c684 | 618 | |
41511585 | 619 | /* Initialize local data structures for CCP. */ |
4ee9c684 | 620 | |
621 | static void | |
41511585 | 622 | ccp_initialize (void) |
4ee9c684 | 623 | { |
41511585 | 624 | basic_block bb; |
4ee9c684 | 625 | |
43959b95 | 626 | const_val = XCNEWVEC (prop_value_t, num_ssa_names); |
4ee9c684 | 627 | |
41511585 | 628 | /* Initialize simulation flags for PHI nodes and statements. */ |
629 | FOR_EACH_BB (bb) | |
4ee9c684 | 630 | { |
75a70cf9 | 631 | gimple_stmt_iterator i; |
4ee9c684 | 632 | |
75a70cf9 | 633 | for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i)) |
41511585 | 634 | { |
75a70cf9 | 635 | gimple stmt = gsi_stmt (i); |
bfa30570 | 636 | bool is_varying = surely_varying_stmt_p (stmt); |
4ee9c684 | 637 | |
bfa30570 | 638 | if (is_varying) |
41511585 | 639 | { |
88dbf20f | 640 | tree def; |
641 | ssa_op_iter iter; | |
642 | ||
643 | /* If the statement will not produce a constant, mark | |
644 | all its outputs VARYING. */ | |
645 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) | |
8edeb88b | 646 | set_value_varying (def); |
41511585 | 647 | } |
75a70cf9 | 648 | prop_set_simulate_again (stmt, !is_varying); |
41511585 | 649 | } |
4ee9c684 | 650 | } |
651 | ||
75a70cf9 | 652 | /* Now process PHI nodes. We never clear the simulate_again flag on |
653 | phi nodes, since we do not know which edges are executable yet, | |
654 | except for phi nodes for virtual operands when we do not do store ccp. */ | |
41511585 | 655 | FOR_EACH_BB (bb) |
4ee9c684 | 656 | { |
75a70cf9 | 657 | gimple_stmt_iterator i; |
41511585 | 658 | |
75a70cf9 | 659 | for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i)) |
660 | { | |
661 | gimple phi = gsi_stmt (i); | |
662 | ||
61207d43 | 663 | if (!is_gimple_reg (gimple_phi_result (phi))) |
75a70cf9 | 664 | prop_set_simulate_again (phi, false); |
bfa30570 | 665 | else |
75a70cf9 | 666 | prop_set_simulate_again (phi, true); |
41511585 | 667 | } |
4ee9c684 | 668 | } |
41511585 | 669 | } |
4ee9c684 | 670 | |
43fb76c1 | 671 | /* Debug count support. Reset the values of ssa names |
672 | VARYING when the total number ssa names analyzed is | |
673 | beyond the debug count specified. */ | |
674 | ||
675 | static void | |
676 | do_dbg_cnt (void) | |
677 | { | |
678 | unsigned i; | |
679 | for (i = 0; i < num_ssa_names; i++) | |
680 | { | |
681 | if (!dbg_cnt (ccp)) | |
682 | { | |
683 | const_val[i].lattice_val = VARYING; | |
684 | const_val[i].value = NULL_TREE; | |
685 | } | |
686 | } | |
687 | } | |
688 | ||
4ee9c684 | 689 | |
88dbf20f | 690 | /* Do final substitution of propagated values, cleanup the flowgraph and |
33a34f1e | 691 | free allocated storage. |
4ee9c684 | 692 | |
33a34f1e | 693 | Return TRUE when something was optimized. */ |
694 | ||
695 | static bool | |
88dbf20f | 696 | ccp_finalize (void) |
4ee9c684 | 697 | { |
43fb76c1 | 698 | bool something_changed; |
699 | ||
700 | do_dbg_cnt (); | |
88dbf20f | 701 | /* Perform substitutions based on the known constant values. */ |
43fb76c1 | 702 | something_changed = substitute_and_fold (const_val, false); |
4ee9c684 | 703 | |
88dbf20f | 704 | free (const_val); |
e004838d | 705 | const_val = NULL; |
33a34f1e | 706 | return something_changed;; |
4ee9c684 | 707 | } |
708 | ||
709 | ||
88dbf20f | 710 | /* Compute the meet operator between *VAL1 and *VAL2. Store the result |
711 | in VAL1. | |
712 | ||
713 | any M UNDEFINED = any | |
88dbf20f | 714 | any M VARYING = VARYING |
715 | Ci M Cj = Ci if (i == j) | |
716 | Ci M Cj = VARYING if (i != j) | |
bfa30570 | 717 | */ |
4ee9c684 | 718 | |
719 | static void | |
88dbf20f | 720 | ccp_lattice_meet (prop_value_t *val1, prop_value_t *val2) |
4ee9c684 | 721 | { |
88dbf20f | 722 | if (val1->lattice_val == UNDEFINED) |
4ee9c684 | 723 | { |
88dbf20f | 724 | /* UNDEFINED M any = any */ |
725 | *val1 = *val2; | |
41511585 | 726 | } |
88dbf20f | 727 | else if (val2->lattice_val == UNDEFINED) |
92481a4d | 728 | { |
88dbf20f | 729 | /* any M UNDEFINED = any |
730 | Nothing to do. VAL1 already contains the value we want. */ | |
731 | ; | |
92481a4d | 732 | } |
88dbf20f | 733 | else if (val1->lattice_val == VARYING |
734 | || val2->lattice_val == VARYING) | |
41511585 | 735 | { |
88dbf20f | 736 | /* any M VARYING = VARYING. */ |
737 | val1->lattice_val = VARYING; | |
738 | val1->value = NULL_TREE; | |
41511585 | 739 | } |
88dbf20f | 740 | else if (val1->lattice_val == CONSTANT |
741 | && val2->lattice_val == CONSTANT | |
61207d43 | 742 | && simple_cst_equal (val1->value, val2->value) == 1) |
41511585 | 743 | { |
88dbf20f | 744 | /* Ci M Cj = Ci if (i == j) |
745 | Ci M Cj = VARYING if (i != j) | |
746 | ||
747 | If these two values come from memory stores, make sure that | |
748 | they come from the same memory reference. */ | |
749 | val1->lattice_val = CONSTANT; | |
750 | val1->value = val1->value; | |
41511585 | 751 | } |
752 | else | |
753 | { | |
88dbf20f | 754 | /* Any other combination is VARYING. */ |
755 | val1->lattice_val = VARYING; | |
756 | val1->value = NULL_TREE; | |
41511585 | 757 | } |
4ee9c684 | 758 | } |
759 | ||
760 | ||
41511585 | 761 | /* Loop through the PHI_NODE's parameters for BLOCK and compare their |
762 | lattice values to determine PHI_NODE's lattice value. The value of a | |
88dbf20f | 763 | PHI node is determined calling ccp_lattice_meet with all the arguments |
41511585 | 764 | of the PHI node that are incoming via executable edges. */ |
4ee9c684 | 765 | |
41511585 | 766 | static enum ssa_prop_result |
75a70cf9 | 767 | ccp_visit_phi_node (gimple phi) |
4ee9c684 | 768 | { |
75a70cf9 | 769 | unsigned i; |
88dbf20f | 770 | prop_value_t *old_val, new_val; |
4ee9c684 | 771 | |
41511585 | 772 | if (dump_file && (dump_flags & TDF_DETAILS)) |
4ee9c684 | 773 | { |
41511585 | 774 | fprintf (dump_file, "\nVisiting PHI node: "); |
75a70cf9 | 775 | print_gimple_stmt (dump_file, phi, 0, dump_flags); |
4ee9c684 | 776 | } |
4ee9c684 | 777 | |
75a70cf9 | 778 | old_val = get_value (gimple_phi_result (phi)); |
41511585 | 779 | switch (old_val->lattice_val) |
780 | { | |
781 | case VARYING: | |
88dbf20f | 782 | return SSA_PROP_VARYING; |
4ee9c684 | 783 | |
41511585 | 784 | case CONSTANT: |
785 | new_val = *old_val; | |
786 | break; | |
4ee9c684 | 787 | |
41511585 | 788 | case UNDEFINED: |
41511585 | 789 | new_val.lattice_val = UNDEFINED; |
88dbf20f | 790 | new_val.value = NULL_TREE; |
41511585 | 791 | break; |
4ee9c684 | 792 | |
41511585 | 793 | default: |
8c0963c4 | 794 | gcc_unreachable (); |
41511585 | 795 | } |
4ee9c684 | 796 | |
75a70cf9 | 797 | for (i = 0; i < gimple_phi_num_args (phi); i++) |
41511585 | 798 | { |
88dbf20f | 799 | /* Compute the meet operator over all the PHI arguments flowing |
800 | through executable edges. */ | |
75a70cf9 | 801 | edge e = gimple_phi_arg_edge (phi, i); |
4ee9c684 | 802 | |
41511585 | 803 | if (dump_file && (dump_flags & TDF_DETAILS)) |
804 | { | |
805 | fprintf (dump_file, | |
806 | "\n Argument #%d (%d -> %d %sexecutable)\n", | |
807 | i, e->src->index, e->dest->index, | |
808 | (e->flags & EDGE_EXECUTABLE) ? "" : "not "); | |
809 | } | |
810 | ||
811 | /* If the incoming edge is executable, Compute the meet operator for | |
812 | the existing value of the PHI node and the current PHI argument. */ | |
813 | if (e->flags & EDGE_EXECUTABLE) | |
814 | { | |
75a70cf9 | 815 | tree arg = gimple_phi_arg (phi, i)->def; |
88dbf20f | 816 | prop_value_t arg_val; |
4ee9c684 | 817 | |
88dbf20f | 818 | if (is_gimple_min_invariant (arg)) |
41511585 | 819 | { |
88dbf20f | 820 | arg_val.lattice_val = CONSTANT; |
821 | arg_val.value = arg; | |
41511585 | 822 | } |
823 | else | |
bfa30570 | 824 | arg_val = *(get_value (arg)); |
4ee9c684 | 825 | |
88dbf20f | 826 | ccp_lattice_meet (&new_val, &arg_val); |
4ee9c684 | 827 | |
41511585 | 828 | if (dump_file && (dump_flags & TDF_DETAILS)) |
829 | { | |
830 | fprintf (dump_file, "\t"); | |
88dbf20f | 831 | print_generic_expr (dump_file, arg, dump_flags); |
832 | dump_lattice_value (dump_file, "\tValue: ", arg_val); | |
41511585 | 833 | fprintf (dump_file, "\n"); |
834 | } | |
4ee9c684 | 835 | |
41511585 | 836 | if (new_val.lattice_val == VARYING) |
837 | break; | |
838 | } | |
839 | } | |
4ee9c684 | 840 | |
841 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
41511585 | 842 | { |
843 | dump_lattice_value (dump_file, "\n PHI node value: ", new_val); | |
844 | fprintf (dump_file, "\n\n"); | |
845 | } | |
846 | ||
bfa30570 | 847 | /* Make the transition to the new value. */ |
75a70cf9 | 848 | if (set_lattice_value (gimple_phi_result (phi), new_val)) |
41511585 | 849 | { |
850 | if (new_val.lattice_val == VARYING) | |
851 | return SSA_PROP_VARYING; | |
852 | else | |
853 | return SSA_PROP_INTERESTING; | |
854 | } | |
855 | else | |
856 | return SSA_PROP_NOT_INTERESTING; | |
4ee9c684 | 857 | } |
858 | ||
fb8ed03f | 859 | /* Return true if we may propagate the address expression ADDR into the |
860 | dereference DEREF and cancel them. */ | |
861 | ||
862 | bool | |
863 | may_propagate_address_into_dereference (tree addr, tree deref) | |
864 | { | |
865 | gcc_assert (INDIRECT_REF_P (deref) | |
866 | && TREE_CODE (addr) == ADDR_EXPR); | |
867 | ||
0d051ece | 868 | /* Don't propagate if ADDR's operand has incomplete type. */ |
869 | if (!COMPLETE_TYPE_P (TREE_TYPE (TREE_OPERAND (addr, 0)))) | |
870 | return false; | |
871 | ||
fb8ed03f | 872 | /* If the address is invariant then we do not need to preserve restrict |
873 | qualifications. But we do need to preserve volatile qualifiers until | |
874 | we can annotate the folded dereference itself properly. */ | |
875 | if (is_gimple_min_invariant (addr) | |
876 | && (!TREE_THIS_VOLATILE (deref) | |
877 | || TYPE_VOLATILE (TREE_TYPE (addr)))) | |
878 | return useless_type_conversion_p (TREE_TYPE (deref), | |
879 | TREE_TYPE (TREE_OPERAND (addr, 0))); | |
880 | ||
881 | /* Else both the address substitution and the folding must result in | |
882 | a valid useless type conversion sequence. */ | |
883 | return (useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (deref, 0)), | |
884 | TREE_TYPE (addr)) | |
885 | && useless_type_conversion_p (TREE_TYPE (deref), | |
886 | TREE_TYPE (TREE_OPERAND (addr, 0)))); | |
887 | } | |
4ee9c684 | 888 | |
41511585 | 889 | /* CCP specific front-end to the non-destructive constant folding |
890 | routines. | |
4ee9c684 | 891 | |
892 | Attempt to simplify the RHS of STMT knowing that one or more | |
893 | operands are constants. | |
894 | ||
895 | If simplification is possible, return the simplified RHS, | |
75a70cf9 | 896 | otherwise return the original RHS or NULL_TREE. */ |
4ee9c684 | 897 | |
898 | static tree | |
75a70cf9 | 899 | ccp_fold (gimple stmt) |
4ee9c684 | 900 | { |
75a70cf9 | 901 | switch (gimple_code (stmt)) |
88dbf20f | 902 | { |
75a70cf9 | 903 | case GIMPLE_ASSIGN: |
904 | { | |
905 | enum tree_code subcode = gimple_assign_rhs_code (stmt); | |
906 | ||
907 | switch (get_gimple_rhs_class (subcode)) | |
908 | { | |
909 | case GIMPLE_SINGLE_RHS: | |
910 | { | |
911 | tree rhs = gimple_assign_rhs1 (stmt); | |
912 | enum tree_code_class kind = TREE_CODE_CLASS (subcode); | |
913 | ||
914 | if (TREE_CODE (rhs) == SSA_NAME) | |
915 | { | |
916 | /* If the RHS is an SSA_NAME, return its known constant value, | |
917 | if any. */ | |
918 | return get_value (rhs)->value; | |
919 | } | |
920 | /* Handle propagating invariant addresses into address operations. | |
921 | The folding we do here matches that in tree-ssa-forwprop.c. */ | |
922 | else if (TREE_CODE (rhs) == ADDR_EXPR) | |
923 | { | |
924 | tree *base; | |
925 | base = &TREE_OPERAND (rhs, 0); | |
926 | while (handled_component_p (*base)) | |
927 | base = &TREE_OPERAND (*base, 0); | |
928 | if (TREE_CODE (*base) == INDIRECT_REF | |
929 | && TREE_CODE (TREE_OPERAND (*base, 0)) == SSA_NAME) | |
930 | { | |
931 | prop_value_t *val = get_value (TREE_OPERAND (*base, 0)); | |
932 | if (val->lattice_val == CONSTANT | |
933 | && TREE_CODE (val->value) == ADDR_EXPR | |
fb8ed03f | 934 | && may_propagate_address_into_dereference |
935 | (val->value, *base)) | |
75a70cf9 | 936 | { |
937 | /* We need to return a new tree, not modify the IL | |
938 | or share parts of it. So play some tricks to | |
939 | avoid manually building it. */ | |
940 | tree ret, save = *base; | |
941 | *base = TREE_OPERAND (val->value, 0); | |
942 | ret = unshare_expr (rhs); | |
943 | recompute_tree_invariant_for_addr_expr (ret); | |
944 | *base = save; | |
945 | return ret; | |
946 | } | |
947 | } | |
948 | } | |
4ee9c684 | 949 | |
75a70cf9 | 950 | if (kind == tcc_reference) |
3e4be816 | 951 | { |
952 | if (TREE_CODE (rhs) == VIEW_CONVERT_EXPR | |
953 | && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME) | |
954 | { | |
955 | prop_value_t *val = get_value (TREE_OPERAND (rhs, 0)); | |
956 | if (val->lattice_val == CONSTANT) | |
957 | return fold_unary (VIEW_CONVERT_EXPR, | |
958 | TREE_TYPE (rhs), val->value); | |
959 | } | |
8edeb88b | 960 | else if (TREE_CODE (rhs) == INDIRECT_REF |
961 | && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME) | |
962 | { | |
963 | prop_value_t *val = get_value (TREE_OPERAND (rhs, 0)); | |
964 | if (val->lattice_val == CONSTANT | |
965 | && TREE_CODE (val->value) == ADDR_EXPR | |
966 | && useless_type_conversion_p (TREE_TYPE (rhs), | |
967 | TREE_TYPE (TREE_TYPE (val->value)))) | |
968 | rhs = TREE_OPERAND (val->value, 0); | |
969 | } | |
3e4be816 | 970 | return fold_const_aggregate_ref (rhs); |
971 | } | |
75a70cf9 | 972 | else if (kind == tcc_declaration) |
973 | return get_symbol_constant_value (rhs); | |
974 | return rhs; | |
975 | } | |
976 | ||
977 | case GIMPLE_UNARY_RHS: | |
978 | { | |
979 | /* Handle unary operators that can appear in GIMPLE form. | |
980 | Note that we know the single operand must be a constant, | |
981 | so this should almost always return a simplified RHS. */ | |
982 | tree lhs = gimple_assign_lhs (stmt); | |
983 | tree op0 = gimple_assign_rhs1 (stmt); | |
984 | ||
985 | /* Simplify the operand down to a constant. */ | |
986 | if (TREE_CODE (op0) == SSA_NAME) | |
987 | { | |
988 | prop_value_t *val = get_value (op0); | |
989 | if (val->lattice_val == CONSTANT) | |
990 | op0 = get_value (op0)->value; | |
991 | } | |
992 | ||
993 | /* Conversions are useless for CCP purposes if they are | |
994 | value-preserving. Thus the restrictions that | |
995 | useless_type_conversion_p places for pointer type conversions | |
996 | do not apply here. Substitution later will only substitute to | |
997 | allowed places. */ | |
d9659041 | 998 | if (CONVERT_EXPR_CODE_P (subcode) |
5768aeb3 | 999 | && POINTER_TYPE_P (TREE_TYPE (lhs)) |
1000 | && POINTER_TYPE_P (TREE_TYPE (op0)) | |
1001 | /* Do not allow differences in volatile qualification | |
1002 | as this might get us confused as to whether a | |
1003 | propagation destination statement is volatile | |
1004 | or not. See PR36988. */ | |
1005 | && (TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (lhs))) | |
1006 | == TYPE_VOLATILE (TREE_TYPE (TREE_TYPE (op0))))) | |
1007 | { | |
1008 | tree tem; | |
1009 | /* Still try to generate a constant of correct type. */ | |
1010 | if (!useless_type_conversion_p (TREE_TYPE (lhs), | |
1011 | TREE_TYPE (op0)) | |
1012 | && ((tem = maybe_fold_offset_to_address | |
1013 | (op0, integer_zero_node, TREE_TYPE (lhs))) | |
1014 | != NULL_TREE)) | |
1015 | return tem; | |
1016 | return op0; | |
1017 | } | |
75a70cf9 | 1018 | |
cd30b839 | 1019 | return fold_unary_ignore_overflow (subcode, |
1020 | gimple_expr_type (stmt), op0); | |
f1fb2997 | 1021 | } |
75a70cf9 | 1022 | |
1023 | case GIMPLE_BINARY_RHS: | |
1024 | { | |
1025 | /* Handle binary operators that can appear in GIMPLE form. */ | |
1026 | tree op0 = gimple_assign_rhs1 (stmt); | |
1027 | tree op1 = gimple_assign_rhs2 (stmt); | |
1028 | ||
1029 | /* Simplify the operands down to constants when appropriate. */ | |
1030 | if (TREE_CODE (op0) == SSA_NAME) | |
1031 | { | |
1032 | prop_value_t *val = get_value (op0); | |
1033 | if (val->lattice_val == CONSTANT) | |
1034 | op0 = val->value; | |
1035 | } | |
1036 | ||
1037 | if (TREE_CODE (op1) == SSA_NAME) | |
1038 | { | |
1039 | prop_value_t *val = get_value (op1); | |
1040 | if (val->lattice_val == CONSTANT) | |
1041 | op1 = val->value; | |
1042 | } | |
1043 | ||
5768aeb3 | 1044 | /* Fold &foo + CST into an invariant reference if possible. */ |
1045 | if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR | |
1046 | && TREE_CODE (op0) == ADDR_EXPR | |
1047 | && TREE_CODE (op1) == INTEGER_CST) | |
1048 | { | |
1049 | tree lhs = gimple_assign_lhs (stmt); | |
1050 | tree tem = maybe_fold_offset_to_address (op0, op1, | |
1051 | TREE_TYPE (lhs)); | |
1052 | if (tem != NULL_TREE) | |
1053 | return tem; | |
1054 | } | |
1055 | ||
75a70cf9 | 1056 | return fold_binary (subcode, gimple_expr_type (stmt), op0, op1); |
1057 | } | |
1058 | ||
1059 | default: | |
1060 | gcc_unreachable (); | |
1061 | } | |
1062 | } | |
1063 | break; | |
4ee9c684 | 1064 | |
75a70cf9 | 1065 | case GIMPLE_CALL: |
f257af64 | 1066 | { |
1067 | tree fn = gimple_call_fn (stmt); | |
1068 | prop_value_t *val; | |
1069 | ||
1070 | if (TREE_CODE (fn) == SSA_NAME) | |
1071 | { | |
1072 | val = get_value (fn); | |
1073 | if (val->lattice_val == CONSTANT) | |
1074 | fn = val->value; | |
1075 | } | |
1076 | if (TREE_CODE (fn) == ADDR_EXPR | |
8ef4f124 | 1077 | && TREE_CODE (TREE_OPERAND (fn, 0)) == FUNCTION_DECL |
f257af64 | 1078 | && DECL_BUILT_IN (TREE_OPERAND (fn, 0))) |
1079 | { | |
1080 | tree *args = XALLOCAVEC (tree, gimple_call_num_args (stmt)); | |
1081 | tree call, retval; | |
1082 | unsigned i; | |
1083 | for (i = 0; i < gimple_call_num_args (stmt); ++i) | |
1084 | { | |
1085 | args[i] = gimple_call_arg (stmt, i); | |
1086 | if (TREE_CODE (args[i]) == SSA_NAME) | |
1087 | { | |
1088 | val = get_value (args[i]); | |
1089 | if (val->lattice_val == CONSTANT) | |
1090 | args[i] = val->value; | |
1091 | } | |
1092 | } | |
1093 | call = build_call_array (gimple_call_return_type (stmt), | |
1094 | fn, gimple_call_num_args (stmt), args); | |
1095 | retval = fold_call_expr (call, false); | |
1096 | if (retval) | |
1097 | /* fold_call_expr wraps the result inside a NOP_EXPR. */ | |
1098 | STRIP_NOPS (retval); | |
1099 | return retval; | |
1100 | } | |
1101 | return NULL_TREE; | |
1102 | } | |
4ee9c684 | 1103 | |
75a70cf9 | 1104 | case GIMPLE_COND: |
1105 | { | |
1106 | /* Handle comparison operators that can appear in GIMPLE form. */ | |
1107 | tree op0 = gimple_cond_lhs (stmt); | |
1108 | tree op1 = gimple_cond_rhs (stmt); | |
1109 | enum tree_code code = gimple_cond_code (stmt); | |
1110 | ||
1111 | /* Simplify the operands down to constants when appropriate. */ | |
1112 | if (TREE_CODE (op0) == SSA_NAME) | |
1113 | { | |
1114 | prop_value_t *val = get_value (op0); | |
1115 | if (val->lattice_val == CONSTANT) | |
1116 | op0 = val->value; | |
1117 | } | |
1118 | ||
1119 | if (TREE_CODE (op1) == SSA_NAME) | |
1120 | { | |
1121 | prop_value_t *val = get_value (op1); | |
1122 | if (val->lattice_val == CONSTANT) | |
1123 | op1 = val->value; | |
1124 | } | |
1125 | ||
1126 | return fold_binary (code, boolean_type_node, op0, op1); | |
1127 | } | |
4ee9c684 | 1128 | |
75a70cf9 | 1129 | case GIMPLE_SWITCH: |
1130 | { | |
1131 | tree rhs = gimple_switch_index (stmt); | |
04236c3a | 1132 | |
75a70cf9 | 1133 | if (TREE_CODE (rhs) == SSA_NAME) |
1134 | { | |
1135 | /* If the RHS is an SSA_NAME, return its known constant value, | |
1136 | if any. */ | |
1137 | return get_value (rhs)->value; | |
1138 | } | |
04236c3a | 1139 | |
75a70cf9 | 1140 | return rhs; |
1141 | } | |
912f109f | 1142 | |
75a70cf9 | 1143 | default: |
1144 | gcc_unreachable (); | |
4ee9c684 | 1145 | } |
4ee9c684 | 1146 | } |
1147 | ||
1148 | ||
8782adcf | 1149 | /* Return the tree representing the element referenced by T if T is an |
1150 | ARRAY_REF or COMPONENT_REF into constant aggregates. Return | |
1151 | NULL_TREE otherwise. */ | |
1152 | ||
e004838d | 1153 | tree |
8782adcf | 1154 | fold_const_aggregate_ref (tree t) |
1155 | { | |
1156 | prop_value_t *value; | |
c75b4594 | 1157 | tree base, ctor, idx, field; |
1158 | unsigned HOST_WIDE_INT cnt; | |
1159 | tree cfield, cval; | |
8782adcf | 1160 | |
8edeb88b | 1161 | if (TREE_CODE_CLASS (TREE_CODE (t)) == tcc_declaration) |
1162 | return get_symbol_constant_value (t); | |
1163 | ||
8782adcf | 1164 | switch (TREE_CODE (t)) |
1165 | { | |
1166 | case ARRAY_REF: | |
1167 | /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its | |
1168 | DECL_INITIAL. If BASE is a nested reference into another | |
1169 | ARRAY_REF or COMPONENT_REF, make a recursive call to resolve | |
1170 | the inner reference. */ | |
1171 | base = TREE_OPERAND (t, 0); | |
1172 | switch (TREE_CODE (base)) | |
1173 | { | |
1174 | case VAR_DECL: | |
1175 | if (!TREE_READONLY (base) | |
1176 | || TREE_CODE (TREE_TYPE (base)) != ARRAY_TYPE | |
1177 | || !targetm.binds_local_p (base)) | |
1178 | return NULL_TREE; | |
1179 | ||
1180 | ctor = DECL_INITIAL (base); | |
1181 | break; | |
1182 | ||
1183 | case ARRAY_REF: | |
1184 | case COMPONENT_REF: | |
1185 | ctor = fold_const_aggregate_ref (base); | |
1186 | break; | |
1187 | ||
04236c3a | 1188 | case STRING_CST: |
1189 | case CONSTRUCTOR: | |
1190 | ctor = base; | |
1191 | break; | |
1192 | ||
8782adcf | 1193 | default: |
1194 | return NULL_TREE; | |
1195 | } | |
1196 | ||
1197 | if (ctor == NULL_TREE | |
4f61cce6 | 1198 | || (TREE_CODE (ctor) != CONSTRUCTOR |
1199 | && TREE_CODE (ctor) != STRING_CST) | |
8782adcf | 1200 | || !TREE_STATIC (ctor)) |
1201 | return NULL_TREE; | |
1202 | ||
1203 | /* Get the index. If we have an SSA_NAME, try to resolve it | |
1204 | with the current lattice value for the SSA_NAME. */ | |
1205 | idx = TREE_OPERAND (t, 1); | |
1206 | switch (TREE_CODE (idx)) | |
1207 | { | |
1208 | case SSA_NAME: | |
bfa30570 | 1209 | if ((value = get_value (idx)) |
8782adcf | 1210 | && value->lattice_val == CONSTANT |
1211 | && TREE_CODE (value->value) == INTEGER_CST) | |
1212 | idx = value->value; | |
1213 | else | |
1214 | return NULL_TREE; | |
1215 | break; | |
1216 | ||
1217 | case INTEGER_CST: | |
1218 | break; | |
1219 | ||
1220 | default: | |
1221 | return NULL_TREE; | |
1222 | } | |
1223 | ||
4f61cce6 | 1224 | /* Fold read from constant string. */ |
1225 | if (TREE_CODE (ctor) == STRING_CST) | |
1226 | { | |
1227 | if ((TYPE_MODE (TREE_TYPE (t)) | |
1228 | == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) | |
1229 | && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) | |
1230 | == MODE_INT) | |
1231 | && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1 | |
1232 | && compare_tree_int (idx, TREE_STRING_LENGTH (ctor)) < 0) | |
7b050b7b | 1233 | return build_int_cst_type (TREE_TYPE (t), |
1234 | (TREE_STRING_POINTER (ctor) | |
1235 | [TREE_INT_CST_LOW (idx)])); | |
4f61cce6 | 1236 | return NULL_TREE; |
1237 | } | |
1238 | ||
8782adcf | 1239 | /* Whoo-hoo! I'll fold ya baby. Yeah! */ |
c75b4594 | 1240 | FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval) |
1241 | if (tree_int_cst_equal (cfield, idx)) | |
590d65aa | 1242 | { |
1243 | STRIP_USELESS_TYPE_CONVERSION (cval); | |
1244 | return cval; | |
1245 | } | |
8782adcf | 1246 | break; |
1247 | ||
1248 | case COMPONENT_REF: | |
1249 | /* Get a CONSTRUCTOR. If BASE is a VAR_DECL, get its | |
1250 | DECL_INITIAL. If BASE is a nested reference into another | |
1251 | ARRAY_REF or COMPONENT_REF, make a recursive call to resolve | |
1252 | the inner reference. */ | |
1253 | base = TREE_OPERAND (t, 0); | |
1254 | switch (TREE_CODE (base)) | |
1255 | { | |
1256 | case VAR_DECL: | |
1257 | if (!TREE_READONLY (base) | |
1258 | || TREE_CODE (TREE_TYPE (base)) != RECORD_TYPE | |
1259 | || !targetm.binds_local_p (base)) | |
1260 | return NULL_TREE; | |
1261 | ||
1262 | ctor = DECL_INITIAL (base); | |
1263 | break; | |
1264 | ||
1265 | case ARRAY_REF: | |
1266 | case COMPONENT_REF: | |
1267 | ctor = fold_const_aggregate_ref (base); | |
1268 | break; | |
1269 | ||
1270 | default: | |
1271 | return NULL_TREE; | |
1272 | } | |
1273 | ||
1274 | if (ctor == NULL_TREE | |
1275 | || TREE_CODE (ctor) != CONSTRUCTOR | |
1276 | || !TREE_STATIC (ctor)) | |
1277 | return NULL_TREE; | |
1278 | ||
1279 | field = TREE_OPERAND (t, 1); | |
1280 | ||
c75b4594 | 1281 | FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval) |
1282 | if (cfield == field | |
8782adcf | 1283 | /* FIXME: Handle bit-fields. */ |
c75b4594 | 1284 | && ! DECL_BIT_FIELD (cfield)) |
590d65aa | 1285 | { |
1286 | STRIP_USELESS_TYPE_CONVERSION (cval); | |
1287 | return cval; | |
1288 | } | |
8782adcf | 1289 | break; |
1290 | ||
908cb59d | 1291 | case REALPART_EXPR: |
1292 | case IMAGPART_EXPR: | |
1293 | { | |
1294 | tree c = fold_const_aggregate_ref (TREE_OPERAND (t, 0)); | |
1295 | if (c && TREE_CODE (c) == COMPLEX_CST) | |
1296 | return fold_build1 (TREE_CODE (t), TREE_TYPE (t), c); | |
1297 | break; | |
1298 | } | |
04236c3a | 1299 | |
1300 | case INDIRECT_REF: | |
1301 | { | |
1302 | tree base = TREE_OPERAND (t, 0); | |
1303 | if (TREE_CODE (base) == SSA_NAME | |
1304 | && (value = get_value (base)) | |
1305 | && value->lattice_val == CONSTANT | |
1306 | && TREE_CODE (value->value) == ADDR_EXPR) | |
1307 | return fold_const_aggregate_ref (TREE_OPERAND (value->value, 0)); | |
1308 | break; | |
1309 | } | |
1310 | ||
8782adcf | 1311 | default: |
1312 | break; | |
1313 | } | |
1314 | ||
1315 | return NULL_TREE; | |
1316 | } | |
75a70cf9 | 1317 | |
1318 | /* Evaluate statement STMT. | |
1319 | Valid only for assignments, calls, conditionals, and switches. */ | |
4ee9c684 | 1320 | |
88dbf20f | 1321 | static prop_value_t |
75a70cf9 | 1322 | evaluate_stmt (gimple stmt) |
4ee9c684 | 1323 | { |
88dbf20f | 1324 | prop_value_t val; |
4f61cce6 | 1325 | tree simplified = NULL_TREE; |
88dbf20f | 1326 | ccp_lattice_t likelyvalue = likely_value (stmt); |
add6ee5e | 1327 | bool is_constant; |
88dbf20f | 1328 | |
add6ee5e | 1329 | fold_defer_overflow_warnings (); |
1330 | ||
4ee9c684 | 1331 | /* If the statement is likely to have a CONSTANT result, then try |
1332 | to fold the statement to determine the constant value. */ | |
75a70cf9 | 1333 | /* FIXME. This is the only place that we call ccp_fold. |
1334 | Since likely_value never returns CONSTANT for calls, we will | |
1335 | not attempt to fold them, including builtins that may profit. */ | |
4ee9c684 | 1336 | if (likelyvalue == CONSTANT) |
1337 | simplified = ccp_fold (stmt); | |
1338 | /* If the statement is likely to have a VARYING result, then do not | |
1339 | bother folding the statement. */ | |
04236c3a | 1340 | else if (likelyvalue == VARYING) |
75a70cf9 | 1341 | { |
590c3166 | 1342 | enum gimple_code code = gimple_code (stmt); |
75a70cf9 | 1343 | if (code == GIMPLE_ASSIGN) |
1344 | { | |
1345 | enum tree_code subcode = gimple_assign_rhs_code (stmt); | |
1346 | ||
1347 | /* Other cases cannot satisfy is_gimple_min_invariant | |
1348 | without folding. */ | |
1349 | if (get_gimple_rhs_class (subcode) == GIMPLE_SINGLE_RHS) | |
1350 | simplified = gimple_assign_rhs1 (stmt); | |
1351 | } | |
1352 | else if (code == GIMPLE_SWITCH) | |
1353 | simplified = gimple_switch_index (stmt); | |
1354 | else | |
1355 | /* These cannot satisfy is_gimple_min_invariant without folding. */ | |
1356 | gcc_assert (code == GIMPLE_CALL || code == GIMPLE_COND); | |
1357 | } | |
4ee9c684 | 1358 | |
add6ee5e | 1359 | is_constant = simplified && is_gimple_min_invariant (simplified); |
1360 | ||
1361 | fold_undefer_overflow_warnings (is_constant, stmt, 0); | |
1362 | ||
912f109f | 1363 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1364 | { | |
1365 | fprintf (dump_file, "which is likely "); | |
1366 | switch (likelyvalue) | |
1367 | { | |
1368 | case CONSTANT: | |
1369 | fprintf (dump_file, "CONSTANT"); | |
1370 | break; | |
1371 | case UNDEFINED: | |
1372 | fprintf (dump_file, "UNDEFINED"); | |
1373 | break; | |
1374 | case VARYING: | |
1375 | fprintf (dump_file, "VARYING"); | |
1376 | break; | |
1377 | default:; | |
1378 | } | |
1379 | fprintf (dump_file, "\n"); | |
1380 | } | |
1381 | ||
add6ee5e | 1382 | if (is_constant) |
4ee9c684 | 1383 | { |
1384 | /* The statement produced a constant value. */ | |
1385 | val.lattice_val = CONSTANT; | |
88dbf20f | 1386 | val.value = simplified; |
4ee9c684 | 1387 | } |
1388 | else | |
1389 | { | |
1390 | /* The statement produced a nonconstant value. If the statement | |
88dbf20f | 1391 | had UNDEFINED operands, then the result of the statement |
1392 | should be UNDEFINED. Otherwise, the statement is VARYING. */ | |
bfa30570 | 1393 | if (likelyvalue == UNDEFINED) |
b765fa12 | 1394 | val.lattice_val = likelyvalue; |
1395 | else | |
1396 | val.lattice_val = VARYING; | |
1397 | ||
88dbf20f | 1398 | val.value = NULL_TREE; |
4ee9c684 | 1399 | } |
41511585 | 1400 | |
1401 | return val; | |
4ee9c684 | 1402 | } |
1403 | ||
41511585 | 1404 | /* Visit the assignment statement STMT. Set the value of its LHS to the |
88dbf20f | 1405 | value computed by the RHS and store LHS in *OUTPUT_P. If STMT |
1406 | creates virtual definitions, set the value of each new name to that | |
75a70cf9 | 1407 | of the RHS (if we can derive a constant out of the RHS). |
1408 | Value-returning call statements also perform an assignment, and | |
1409 | are handled here. */ | |
4ee9c684 | 1410 | |
41511585 | 1411 | static enum ssa_prop_result |
75a70cf9 | 1412 | visit_assignment (gimple stmt, tree *output_p) |
4ee9c684 | 1413 | { |
88dbf20f | 1414 | prop_value_t val; |
88dbf20f | 1415 | enum ssa_prop_result retval; |
4ee9c684 | 1416 | |
75a70cf9 | 1417 | tree lhs = gimple_get_lhs (stmt); |
4ee9c684 | 1418 | |
75a70cf9 | 1419 | gcc_assert (gimple_code (stmt) != GIMPLE_CALL |
1420 | || gimple_call_lhs (stmt) != NULL_TREE); | |
1421 | ||
1422 | if (gimple_assign_copy_p (stmt)) | |
41511585 | 1423 | { |
75a70cf9 | 1424 | tree rhs = gimple_assign_rhs1 (stmt); |
88dbf20f | 1425 | |
75a70cf9 | 1426 | if (TREE_CODE (rhs) == SSA_NAME) |
1427 | { | |
1428 | /* For a simple copy operation, we copy the lattice values. */ | |
1429 | prop_value_t *nval = get_value (rhs); | |
1430 | val = *nval; | |
1431 | } | |
88dbf20f | 1432 | else |
75a70cf9 | 1433 | val = evaluate_stmt (stmt); |
41511585 | 1434 | } |
1435 | else | |
75a70cf9 | 1436 | /* Evaluate the statement, which could be |
1437 | either a GIMPLE_ASSIGN or a GIMPLE_CALL. */ | |
04236c3a | 1438 | val = evaluate_stmt (stmt); |
4ee9c684 | 1439 | |
88dbf20f | 1440 | retval = SSA_PROP_NOT_INTERESTING; |
4ee9c684 | 1441 | |
41511585 | 1442 | /* Set the lattice value of the statement's output. */ |
88dbf20f | 1443 | if (TREE_CODE (lhs) == SSA_NAME) |
4ee9c684 | 1444 | { |
88dbf20f | 1445 | /* If STMT is an assignment to an SSA_NAME, we only have one |
1446 | value to set. */ | |
1447 | if (set_lattice_value (lhs, val)) | |
1448 | { | |
1449 | *output_p = lhs; | |
1450 | if (val.lattice_val == VARYING) | |
1451 | retval = SSA_PROP_VARYING; | |
1452 | else | |
1453 | retval = SSA_PROP_INTERESTING; | |
1454 | } | |
4ee9c684 | 1455 | } |
88dbf20f | 1456 | |
1457 | return retval; | |
4ee9c684 | 1458 | } |
1459 | ||
4ee9c684 | 1460 | |
41511585 | 1461 | /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING |
1462 | if it can determine which edge will be taken. Otherwise, return | |
1463 | SSA_PROP_VARYING. */ | |
1464 | ||
1465 | static enum ssa_prop_result | |
75a70cf9 | 1466 | visit_cond_stmt (gimple stmt, edge *taken_edge_p) |
4ee9c684 | 1467 | { |
88dbf20f | 1468 | prop_value_t val; |
41511585 | 1469 | basic_block block; |
1470 | ||
75a70cf9 | 1471 | block = gimple_bb (stmt); |
41511585 | 1472 | val = evaluate_stmt (stmt); |
1473 | ||
1474 | /* Find which edge out of the conditional block will be taken and add it | |
1475 | to the worklist. If no single edge can be determined statically, | |
1476 | return SSA_PROP_VARYING to feed all the outgoing edges to the | |
1477 | propagation engine. */ | |
88dbf20f | 1478 | *taken_edge_p = val.value ? find_taken_edge (block, val.value) : 0; |
41511585 | 1479 | if (*taken_edge_p) |
1480 | return SSA_PROP_INTERESTING; | |
1481 | else | |
1482 | return SSA_PROP_VARYING; | |
4ee9c684 | 1483 | } |
1484 | ||
4ee9c684 | 1485 | |
41511585 | 1486 | /* Evaluate statement STMT. If the statement produces an output value and |
1487 | its evaluation changes the lattice value of its output, return | |
1488 | SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the | |
1489 | output value. | |
1490 | ||
1491 | If STMT is a conditional branch and we can determine its truth | |
1492 | value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying | |
1493 | value, return SSA_PROP_VARYING. */ | |
4ee9c684 | 1494 | |
41511585 | 1495 | static enum ssa_prop_result |
75a70cf9 | 1496 | ccp_visit_stmt (gimple stmt, edge *taken_edge_p, tree *output_p) |
41511585 | 1497 | { |
41511585 | 1498 | tree def; |
1499 | ssa_op_iter iter; | |
4ee9c684 | 1500 | |
41511585 | 1501 | if (dump_file && (dump_flags & TDF_DETAILS)) |
4ee9c684 | 1502 | { |
88dbf20f | 1503 | fprintf (dump_file, "\nVisiting statement:\n"); |
75a70cf9 | 1504 | print_gimple_stmt (dump_file, stmt, 0, dump_flags); |
4ee9c684 | 1505 | } |
4ee9c684 | 1506 | |
75a70cf9 | 1507 | switch (gimple_code (stmt)) |
4ee9c684 | 1508 | { |
75a70cf9 | 1509 | case GIMPLE_ASSIGN: |
1510 | /* If the statement is an assignment that produces a single | |
1511 | output value, evaluate its RHS to see if the lattice value of | |
1512 | its output has changed. */ | |
1513 | return visit_assignment (stmt, output_p); | |
1514 | ||
1515 | case GIMPLE_CALL: | |
1516 | /* A value-returning call also performs an assignment. */ | |
1517 | if (gimple_call_lhs (stmt) != NULL_TREE) | |
1518 | return visit_assignment (stmt, output_p); | |
1519 | break; | |
1520 | ||
1521 | case GIMPLE_COND: | |
1522 | case GIMPLE_SWITCH: | |
1523 | /* If STMT is a conditional branch, see if we can determine | |
1524 | which branch will be taken. */ | |
1525 | /* FIXME. It appears that we should be able to optimize | |
1526 | computed GOTOs here as well. */ | |
1527 | return visit_cond_stmt (stmt, taken_edge_p); | |
1528 | ||
1529 | default: | |
1530 | break; | |
4ee9c684 | 1531 | } |
4ee9c684 | 1532 | |
41511585 | 1533 | /* Any other kind of statement is not interesting for constant |
1534 | propagation and, therefore, not worth simulating. */ | |
41511585 | 1535 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1536 | fprintf (dump_file, "No interesting values produced. Marked VARYING.\n"); | |
4ee9c684 | 1537 | |
41511585 | 1538 | /* Definitions made by statements other than assignments to |
1539 | SSA_NAMEs represent unknown modifications to their outputs. | |
1540 | Mark them VARYING. */ | |
88dbf20f | 1541 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) |
1542 | { | |
61207d43 | 1543 | prop_value_t v = { VARYING, NULL_TREE }; |
88dbf20f | 1544 | set_lattice_value (def, v); |
1545 | } | |
4ee9c684 | 1546 | |
41511585 | 1547 | return SSA_PROP_VARYING; |
1548 | } | |
4ee9c684 | 1549 | |
4ee9c684 | 1550 | |
88dbf20f | 1551 | /* Main entry point for SSA Conditional Constant Propagation. */ |
41511585 | 1552 | |
33a34f1e | 1553 | static unsigned int |
61207d43 | 1554 | do_ssa_ccp (void) |
41511585 | 1555 | { |
1556 | ccp_initialize (); | |
1557 | ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node); | |
33a34f1e | 1558 | if (ccp_finalize ()) |
eb9161e7 | 1559 | return (TODO_cleanup_cfg | TODO_update_ssa | TODO_remove_unused_locals); |
33a34f1e | 1560 | else |
1561 | return 0; | |
4ee9c684 | 1562 | } |
1563 | ||
5664499b | 1564 | |
1565 | static bool | |
41511585 | 1566 | gate_ccp (void) |
5664499b | 1567 | { |
41511585 | 1568 | return flag_tree_ccp != 0; |
5664499b | 1569 | } |
1570 | ||
4ee9c684 | 1571 | |
20099e35 | 1572 | struct gimple_opt_pass pass_ccp = |
41511585 | 1573 | { |
20099e35 | 1574 | { |
1575 | GIMPLE_PASS, | |
41511585 | 1576 | "ccp", /* name */ |
1577 | gate_ccp, /* gate */ | |
88dbf20f | 1578 | do_ssa_ccp, /* execute */ |
41511585 | 1579 | NULL, /* sub */ |
1580 | NULL, /* next */ | |
1581 | 0, /* static_pass_number */ | |
1582 | TV_TREE_CCP, /* tv_id */ | |
49290934 | 1583 | PROP_cfg | PROP_ssa, /* properties_required */ |
41511585 | 1584 | 0, /* properties_provided */ |
b6246c40 | 1585 | 0, /* properties_destroyed */ |
41511585 | 1586 | 0, /* todo_flags_start */ |
33a34f1e | 1587 | TODO_dump_func | TODO_verify_ssa |
20099e35 | 1588 | | TODO_verify_stmts | TODO_ggc_collect/* todo_flags_finish */ |
1589 | } | |
41511585 | 1590 | }; |
4ee9c684 | 1591 | |
4ee9c684 | 1592 | |
4ee9c684 | 1593 | /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X]. |
1594 | BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE | |
0bed3869 | 1595 | is the desired result type. */ |
4ee9c684 | 1596 | |
1597 | static tree | |
b7488229 | 1598 | maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type, |
1599 | bool allow_negative_idx) | |
4ee9c684 | 1600 | { |
e71da05f | 1601 | tree min_idx, idx, idx_type, elt_offset = integer_zero_node; |
6374121b | 1602 | tree array_type, elt_type, elt_size; |
b513c084 | 1603 | tree domain_type; |
6374121b | 1604 | |
1605 | /* If BASE is an ARRAY_REF, we can pick up another offset (this time | |
1606 | measured in units of the size of elements type) from that ARRAY_REF). | |
1607 | We can't do anything if either is variable. | |
1608 | ||
1609 | The case we handle here is *(&A[N]+O). */ | |
1610 | if (TREE_CODE (base) == ARRAY_REF) | |
1611 | { | |
1612 | tree low_bound = array_ref_low_bound (base); | |
1613 | ||
1614 | elt_offset = TREE_OPERAND (base, 1); | |
1615 | if (TREE_CODE (low_bound) != INTEGER_CST | |
1616 | || TREE_CODE (elt_offset) != INTEGER_CST) | |
1617 | return NULL_TREE; | |
1618 | ||
1619 | elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0); | |
1620 | base = TREE_OPERAND (base, 0); | |
1621 | } | |
4ee9c684 | 1622 | |
1623 | /* Ignore stupid user tricks of indexing non-array variables. */ | |
1624 | array_type = TREE_TYPE (base); | |
1625 | if (TREE_CODE (array_type) != ARRAY_TYPE) | |
1626 | return NULL_TREE; | |
1627 | elt_type = TREE_TYPE (array_type); | |
c8ca3ee7 | 1628 | if (!useless_type_conversion_p (orig_type, elt_type)) |
4ee9c684 | 1629 | return NULL_TREE; |
e71da05f | 1630 | |
1631 | /* Use signed size type for intermediate computation on the index. */ | |
1632 | idx_type = signed_type_for (size_type_node); | |
1633 | ||
6374121b | 1634 | /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the |
1635 | element type (so we can use the alignment if it's not constant). | |
1636 | Otherwise, compute the offset as an index by using a division. If the | |
1637 | division isn't exact, then don't do anything. */ | |
4ee9c684 | 1638 | elt_size = TYPE_SIZE_UNIT (elt_type); |
3b45913d | 1639 | if (!elt_size) |
1640 | return NULL; | |
6374121b | 1641 | if (integer_zerop (offset)) |
1642 | { | |
1643 | if (TREE_CODE (elt_size) != INTEGER_CST) | |
1644 | elt_size = size_int (TYPE_ALIGN (elt_type)); | |
4ee9c684 | 1645 | |
e71da05f | 1646 | idx = build_int_cst (idx_type, 0); |
6374121b | 1647 | } |
1648 | else | |
1649 | { | |
1650 | unsigned HOST_WIDE_INT lquo, lrem; | |
1651 | HOST_WIDE_INT hquo, hrem; | |
e71da05f | 1652 | double_int soffset; |
6374121b | 1653 | |
e71da05f | 1654 | /* The final array offset should be signed, so we need |
1655 | to sign-extend the (possibly pointer) offset here | |
1656 | and use signed division. */ | |
1657 | soffset = double_int_sext (tree_to_double_int (offset), | |
1658 | TYPE_PRECISION (TREE_TYPE (offset))); | |
6374121b | 1659 | if (TREE_CODE (elt_size) != INTEGER_CST |
e71da05f | 1660 | || div_and_round_double (TRUNC_DIV_EXPR, 0, |
1661 | soffset.low, soffset.high, | |
6374121b | 1662 | TREE_INT_CST_LOW (elt_size), |
1663 | TREE_INT_CST_HIGH (elt_size), | |
1664 | &lquo, &hquo, &lrem, &hrem) | |
1665 | || lrem || hrem) | |
1666 | return NULL_TREE; | |
4ee9c684 | 1667 | |
e71da05f | 1668 | idx = build_int_cst_wide (idx_type, lquo, hquo); |
6374121b | 1669 | } |
1670 | ||
1671 | /* Assume the low bound is zero. If there is a domain type, get the | |
1672 | low bound, if any, convert the index into that type, and add the | |
1673 | low bound. */ | |
e71da05f | 1674 | min_idx = build_int_cst (idx_type, 0); |
b513c084 | 1675 | domain_type = TYPE_DOMAIN (array_type); |
1676 | if (domain_type) | |
4ee9c684 | 1677 | { |
b513c084 | 1678 | idx_type = domain_type; |
e71da05f | 1679 | if (TYPE_MIN_VALUE (idx_type)) |
1680 | min_idx = TYPE_MIN_VALUE (idx_type); | |
6374121b | 1681 | else |
e71da05f | 1682 | min_idx = fold_convert (idx_type, min_idx); |
6374121b | 1683 | |
1684 | if (TREE_CODE (min_idx) != INTEGER_CST) | |
1685 | return NULL_TREE; | |
1686 | ||
e71da05f | 1687 | elt_offset = fold_convert (idx_type, elt_offset); |
4ee9c684 | 1688 | } |
1689 | ||
6374121b | 1690 | if (!integer_zerop (min_idx)) |
1691 | idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0); | |
1692 | if (!integer_zerop (elt_offset)) | |
1693 | idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0); | |
1694 | ||
e71da05f | 1695 | /* Make sure to possibly truncate late after offsetting. */ |
1696 | idx = fold_convert (idx_type, idx); | |
1697 | ||
b513c084 | 1698 | /* We don't want to construct access past array bounds. For example |
b7488229 | 1699 | char *(c[4]); |
1700 | c[3][2]; | |
1701 | should not be simplified into (*c)[14] or tree-vrp will | |
1702 | give false warnings. The same is true for | |
1703 | struct A { long x; char d[0]; } *a; | |
1704 | (char *)a - 4; | |
1705 | which should be not folded to &a->d[-8]. */ | |
1706 | if (domain_type | |
1707 | && TYPE_MAX_VALUE (domain_type) | |
b513c084 | 1708 | && TREE_CODE (TYPE_MAX_VALUE (domain_type)) == INTEGER_CST) |
1709 | { | |
1710 | tree up_bound = TYPE_MAX_VALUE (domain_type); | |
1711 | ||
1712 | if (tree_int_cst_lt (up_bound, idx) | |
1713 | /* Accesses after the end of arrays of size 0 (gcc | |
1714 | extension) and 1 are likely intentional ("struct | |
1715 | hack"). */ | |
1716 | && compare_tree_int (up_bound, 1) > 0) | |
1717 | return NULL_TREE; | |
1718 | } | |
b7488229 | 1719 | if (domain_type |
1720 | && TYPE_MIN_VALUE (domain_type)) | |
1721 | { | |
1722 | if (!allow_negative_idx | |
1723 | && TREE_CODE (TYPE_MIN_VALUE (domain_type)) == INTEGER_CST | |
1724 | && tree_int_cst_lt (idx, TYPE_MIN_VALUE (domain_type))) | |
1725 | return NULL_TREE; | |
1726 | } | |
1727 | else if (!allow_negative_idx | |
1728 | && compare_tree_int (idx, 0) < 0) | |
1729 | return NULL_TREE; | |
b513c084 | 1730 | |
d3828421 | 1731 | return build4 (ARRAY_REF, elt_type, base, idx, NULL_TREE, NULL_TREE); |
4ee9c684 | 1732 | } |
1733 | ||
41511585 | 1734 | |
3b45913d | 1735 | /* Attempt to fold *(S+O) to S.X. |
4ee9c684 | 1736 | BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE |
1737 | is the desired result type. */ | |
4ee9c684 | 1738 | |
3b45913d | 1739 | static tree |
4ee9c684 | 1740 | maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset, |
1741 | tree orig_type, bool base_is_ptr) | |
1742 | { | |
6d5d8428 | 1743 | tree f, t, field_type, tail_array_field, field_offset; |
d9745cea | 1744 | tree ret; |
1745 | tree new_base; | |
4ee9c684 | 1746 | |
1747 | if (TREE_CODE (record_type) != RECORD_TYPE | |
1748 | && TREE_CODE (record_type) != UNION_TYPE | |
1749 | && TREE_CODE (record_type) != QUAL_UNION_TYPE) | |
1750 | return NULL_TREE; | |
1751 | ||
1752 | /* Short-circuit silly cases. */ | |
c8ca3ee7 | 1753 | if (useless_type_conversion_p (record_type, orig_type)) |
4ee9c684 | 1754 | return NULL_TREE; |
1755 | ||
1756 | tail_array_field = NULL_TREE; | |
1757 | for (f = TYPE_FIELDS (record_type); f ; f = TREE_CHAIN (f)) | |
1758 | { | |
1759 | int cmp; | |
1760 | ||
1761 | if (TREE_CODE (f) != FIELD_DECL) | |
1762 | continue; | |
1763 | if (DECL_BIT_FIELD (f)) | |
1764 | continue; | |
6d5d8428 | 1765 | |
3b45913d | 1766 | if (!DECL_FIELD_OFFSET (f)) |
1767 | continue; | |
6d5d8428 | 1768 | field_offset = byte_position (f); |
1769 | if (TREE_CODE (field_offset) != INTEGER_CST) | |
4ee9c684 | 1770 | continue; |
1771 | ||
1772 | /* ??? Java creates "interesting" fields for representing base classes. | |
1773 | They have no name, and have no context. With no context, we get into | |
1774 | trouble with nonoverlapping_component_refs_p. Skip them. */ | |
1775 | if (!DECL_FIELD_CONTEXT (f)) | |
1776 | continue; | |
1777 | ||
1778 | /* The previous array field isn't at the end. */ | |
1779 | tail_array_field = NULL_TREE; | |
1780 | ||
1781 | /* Check to see if this offset overlaps with the field. */ | |
6d5d8428 | 1782 | cmp = tree_int_cst_compare (field_offset, offset); |
4ee9c684 | 1783 | if (cmp > 0) |
1784 | continue; | |
1785 | ||
1786 | field_type = TREE_TYPE (f); | |
4ee9c684 | 1787 | |
1788 | /* Here we exactly match the offset being checked. If the types match, | |
1789 | then we can return that field. */ | |
115073ff | 1790 | if (cmp == 0 |
c8ca3ee7 | 1791 | && useless_type_conversion_p (orig_type, field_type)) |
4ee9c684 | 1792 | { |
1793 | if (base_is_ptr) | |
1794 | base = build1 (INDIRECT_REF, record_type, base); | |
40b19772 | 1795 | t = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE); |
4ee9c684 | 1796 | return t; |
1797 | } | |
115073ff | 1798 | |
1799 | /* Don't care about offsets into the middle of scalars. */ | |
1800 | if (!AGGREGATE_TYPE_P (field_type)) | |
1801 | continue; | |
4ee9c684 | 1802 | |
115073ff | 1803 | /* Check for array at the end of the struct. This is often |
1804 | used as for flexible array members. We should be able to | |
1805 | turn this into an array access anyway. */ | |
1806 | if (TREE_CODE (field_type) == ARRAY_TYPE) | |
1807 | tail_array_field = f; | |
1808 | ||
1809 | /* Check the end of the field against the offset. */ | |
1810 | if (!DECL_SIZE_UNIT (f) | |
1811 | || TREE_CODE (DECL_SIZE_UNIT (f)) != INTEGER_CST) | |
1812 | continue; | |
1813 | t = int_const_binop (MINUS_EXPR, offset, field_offset, 1); | |
1814 | if (!tree_int_cst_lt (t, DECL_SIZE_UNIT (f))) | |
1815 | continue; | |
4ee9c684 | 1816 | |
115073ff | 1817 | /* If we matched, then set offset to the displacement into |
1818 | this field. */ | |
d9745cea | 1819 | if (base_is_ptr) |
1820 | new_base = build1 (INDIRECT_REF, record_type, base); | |
1821 | else | |
1822 | new_base = base; | |
1823 | new_base = build3 (COMPONENT_REF, field_type, new_base, f, NULL_TREE); | |
1824 | ||
1825 | /* Recurse to possibly find the match. */ | |
b7488229 | 1826 | ret = maybe_fold_offset_to_array_ref (new_base, t, orig_type, |
1827 | f == TYPE_FIELDS (record_type)); | |
d9745cea | 1828 | if (ret) |
1829 | return ret; | |
1830 | ret = maybe_fold_offset_to_component_ref (field_type, new_base, t, | |
1831 | orig_type, false); | |
1832 | if (ret) | |
1833 | return ret; | |
4ee9c684 | 1834 | } |
1835 | ||
1836 | if (!tail_array_field) | |
1837 | return NULL_TREE; | |
1838 | ||
1839 | f = tail_array_field; | |
1840 | field_type = TREE_TYPE (f); | |
115073ff | 1841 | offset = int_const_binop (MINUS_EXPR, offset, byte_position (f), 1); |
4ee9c684 | 1842 | |
4ee9c684 | 1843 | /* If we get here, we've got an aggregate field, and a possibly |
365db11e | 1844 | nonzero offset into them. Recurse and hope for a valid match. */ |
4ee9c684 | 1845 | if (base_is_ptr) |
1846 | base = build1 (INDIRECT_REF, record_type, base); | |
40b19772 | 1847 | base = build3 (COMPONENT_REF, field_type, base, f, NULL_TREE); |
4ee9c684 | 1848 | |
b7488229 | 1849 | t = maybe_fold_offset_to_array_ref (base, offset, orig_type, |
1850 | f == TYPE_FIELDS (record_type)); | |
4ee9c684 | 1851 | if (t) |
1852 | return t; | |
1853 | return maybe_fold_offset_to_component_ref (field_type, base, offset, | |
1854 | orig_type, false); | |
1855 | } | |
1856 | ||
3b45913d | 1857 | /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE->field_of_orig_type |
1858 | or BASE[index] or by combination of those. | |
1859 | ||
1860 | Before attempting the conversion strip off existing ADDR_EXPRs and | |
1861 | handled component refs. */ | |
1862 | ||
1863 | tree | |
1864 | maybe_fold_offset_to_reference (tree base, tree offset, tree orig_type) | |
1865 | { | |
1866 | tree ret; | |
1867 | tree type; | |
1868 | bool base_is_ptr = true; | |
1869 | ||
1870 | STRIP_NOPS (base); | |
1871 | if (TREE_CODE (base) == ADDR_EXPR) | |
1872 | { | |
1873 | base_is_ptr = false; | |
1874 | ||
1875 | base = TREE_OPERAND (base, 0); | |
1876 | ||
1877 | /* Handle case where existing COMPONENT_REF pick e.g. wrong field of union, | |
1878 | so it needs to be removed and new COMPONENT_REF constructed. | |
1879 | The wrong COMPONENT_REF are often constructed by folding the | |
1880 | (type *)&object within the expression (type *)&object+offset */ | |
5768aeb3 | 1881 | if (handled_component_p (base)) |
3b45913d | 1882 | { |
1883 | HOST_WIDE_INT sub_offset, size, maxsize; | |
1884 | tree newbase; | |
1885 | newbase = get_ref_base_and_extent (base, &sub_offset, | |
1886 | &size, &maxsize); | |
1887 | gcc_assert (newbase); | |
5768aeb3 | 1888 | if (size == maxsize |
844461a0 | 1889 | && size != -1 |
5768aeb3 | 1890 | && !(sub_offset & (BITS_PER_UNIT - 1))) |
3b45913d | 1891 | { |
1892 | base = newbase; | |
1893 | if (sub_offset) | |
1894 | offset = int_const_binop (PLUS_EXPR, offset, | |
1895 | build_int_cst (TREE_TYPE (offset), | |
1896 | sub_offset / BITS_PER_UNIT), 1); | |
1897 | } | |
1898 | } | |
c8ca3ee7 | 1899 | if (useless_type_conversion_p (orig_type, TREE_TYPE (base)) |
3b45913d | 1900 | && integer_zerop (offset)) |
1901 | return base; | |
1902 | type = TREE_TYPE (base); | |
1903 | } | |
1904 | else | |
1905 | { | |
1906 | base_is_ptr = true; | |
1907 | if (!POINTER_TYPE_P (TREE_TYPE (base))) | |
1908 | return NULL_TREE; | |
1909 | type = TREE_TYPE (TREE_TYPE (base)); | |
1910 | } | |
1911 | ret = maybe_fold_offset_to_component_ref (type, base, offset, | |
1912 | orig_type, base_is_ptr); | |
1913 | if (!ret) | |
1914 | { | |
1915 | if (base_is_ptr) | |
1916 | base = build1 (INDIRECT_REF, type, base); | |
b7488229 | 1917 | ret = maybe_fold_offset_to_array_ref (base, offset, orig_type, true); |
3b45913d | 1918 | } |
1919 | return ret; | |
1920 | } | |
41511585 | 1921 | |
5768aeb3 | 1922 | /* Attempt to express (ORIG_TYPE)&BASE+OFFSET as &BASE->field_of_orig_type |
1923 | or &BASE[index] or by combination of those. | |
1924 | ||
1925 | Before attempting the conversion strip off existing component refs. */ | |
1926 | ||
1927 | tree | |
1928 | maybe_fold_offset_to_address (tree addr, tree offset, tree orig_type) | |
1929 | { | |
1930 | tree t; | |
1931 | ||
1932 | gcc_assert (POINTER_TYPE_P (TREE_TYPE (addr)) | |
1933 | && POINTER_TYPE_P (orig_type)); | |
1934 | ||
1935 | t = maybe_fold_offset_to_reference (addr, offset, TREE_TYPE (orig_type)); | |
1936 | if (t != NULL_TREE) | |
1937 | { | |
1938 | tree orig = addr; | |
1939 | tree ptr_type; | |
1940 | ||
1941 | /* For __builtin_object_size to function correctly we need to | |
1942 | make sure not to fold address arithmetic so that we change | |
1943 | reference from one array to another. This would happen for | |
1944 | example for | |
1945 | ||
1946 | struct X { char s1[10]; char s2[10] } s; | |
1947 | char *foo (void) { return &s.s2[-4]; } | |
1948 | ||
1949 | where we need to avoid generating &s.s1[6]. As the C and | |
1950 | C++ frontends create different initial trees | |
1951 | (char *) &s.s1 + -4 vs. &s.s1[-4] we have to do some | |
1952 | sophisticated comparisons here. Note that checking for the | |
1953 | condition after the fact is easier than trying to avoid doing | |
1954 | the folding. */ | |
1955 | STRIP_NOPS (orig); | |
1956 | if (TREE_CODE (orig) == ADDR_EXPR) | |
1957 | orig = TREE_OPERAND (orig, 0); | |
1958 | if ((TREE_CODE (orig) == ARRAY_REF | |
1959 | || (TREE_CODE (orig) == COMPONENT_REF | |
1960 | && TREE_CODE (TREE_TYPE (TREE_OPERAND (orig, 1))) == ARRAY_TYPE)) | |
1961 | && (TREE_CODE (t) == ARRAY_REF | |
bc79a76b | 1962 | || TREE_CODE (t) == COMPONENT_REF) |
5768aeb3 | 1963 | && !operand_equal_p (TREE_CODE (orig) == ARRAY_REF |
1964 | ? TREE_OPERAND (orig, 0) : orig, | |
1965 | TREE_CODE (t) == ARRAY_REF | |
1966 | ? TREE_OPERAND (t, 0) : t, 0)) | |
1967 | return NULL_TREE; | |
1968 | ||
1969 | ptr_type = build_pointer_type (TREE_TYPE (t)); | |
1970 | if (!useless_type_conversion_p (orig_type, ptr_type)) | |
1971 | return NULL_TREE; | |
1972 | return build_fold_addr_expr_with_type (t, ptr_type); | |
1973 | } | |
1974 | ||
1975 | return NULL_TREE; | |
1976 | } | |
1977 | ||
4ee9c684 | 1978 | /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET). |
1979 | Return the simplified expression, or NULL if nothing could be done. */ | |
1980 | ||
1981 | static tree | |
1982 | maybe_fold_stmt_indirect (tree expr, tree base, tree offset) | |
1983 | { | |
1984 | tree t; | |
5acf8305 | 1985 | bool volatile_p = TREE_THIS_VOLATILE (expr); |
4ee9c684 | 1986 | |
1987 | /* We may well have constructed a double-nested PLUS_EXPR via multiple | |
1988 | substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that | |
1989 | are sometimes added. */ | |
1990 | base = fold (base); | |
40bcfc86 | 1991 | STRIP_TYPE_NOPS (base); |
4ee9c684 | 1992 | TREE_OPERAND (expr, 0) = base; |
1993 | ||
1994 | /* One possibility is that the address reduces to a string constant. */ | |
1995 | t = fold_read_from_constant_string (expr); | |
1996 | if (t) | |
1997 | return t; | |
1998 | ||
0de36bdb | 1999 | /* Add in any offset from a POINTER_PLUS_EXPR. */ |
2000 | if (TREE_CODE (base) == POINTER_PLUS_EXPR) | |
4ee9c684 | 2001 | { |
2002 | tree offset2; | |
2003 | ||
2004 | offset2 = TREE_OPERAND (base, 1); | |
2005 | if (TREE_CODE (offset2) != INTEGER_CST) | |
2006 | return NULL_TREE; | |
2007 | base = TREE_OPERAND (base, 0); | |
2008 | ||
0de36bdb | 2009 | offset = fold_convert (sizetype, |
2010 | int_const_binop (PLUS_EXPR, offset, offset2, 1)); | |
4ee9c684 | 2011 | } |
2012 | ||
2013 | if (TREE_CODE (base) == ADDR_EXPR) | |
2014 | { | |
3b45913d | 2015 | tree base_addr = base; |
2016 | ||
4ee9c684 | 2017 | /* Strip the ADDR_EXPR. */ |
2018 | base = TREE_OPERAND (base, 0); | |
2019 | ||
e67e5e1f | 2020 | /* Fold away CONST_DECL to its value, if the type is scalar. */ |
2021 | if (TREE_CODE (base) == CONST_DECL | |
0a685b29 | 2022 | && is_gimple_min_invariant (DECL_INITIAL (base))) |
e67e5e1f | 2023 | return DECL_INITIAL (base); |
2024 | ||
4ee9c684 | 2025 | /* Try folding *(&B+O) to B.X. */ |
3b45913d | 2026 | t = maybe_fold_offset_to_reference (base_addr, offset, |
2027 | TREE_TYPE (expr)); | |
4ee9c684 | 2028 | if (t) |
5acf8305 | 2029 | { |
bcc7452f | 2030 | /* Preserve volatileness of the original expression. |
2031 | We can end up with a plain decl here which is shared | |
2032 | and we shouldn't mess with its flags. */ | |
2033 | if (!SSA_VAR_P (t)) | |
2034 | TREE_THIS_VOLATILE (t) = volatile_p; | |
5acf8305 | 2035 | return t; |
2036 | } | |
4ee9c684 | 2037 | } |
2038 | else | |
2039 | { | |
2040 | /* We can get here for out-of-range string constant accesses, | |
2041 | such as "_"[3]. Bail out of the entire substitution search | |
2042 | and arrange for the entire statement to be replaced by a | |
06b27565 | 2043 | call to __builtin_trap. In all likelihood this will all be |
4ee9c684 | 2044 | constant-folded away, but in the meantime we can't leave with |
2045 | something that get_expr_operands can't understand. */ | |
2046 | ||
2047 | t = base; | |
2048 | STRIP_NOPS (t); | |
2049 | if (TREE_CODE (t) == ADDR_EXPR | |
2050 | && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST) | |
2051 | { | |
2052 | /* FIXME: Except that this causes problems elsewhere with dead | |
1fa3a8f6 | 2053 | code not being deleted, and we die in the rtl expanders |
4ee9c684 | 2054 | because we failed to remove some ssa_name. In the meantime, |
2055 | just return zero. */ | |
2056 | /* FIXME2: This condition should be signaled by | |
2057 | fold_read_from_constant_string directly, rather than | |
2058 | re-checking for it here. */ | |
2059 | return integer_zero_node; | |
2060 | } | |
2061 | ||
2062 | /* Try folding *(B+O) to B->X. Still an improvement. */ | |
2063 | if (POINTER_TYPE_P (TREE_TYPE (base))) | |
2064 | { | |
3b45913d | 2065 | t = maybe_fold_offset_to_reference (base, offset, |
2066 | TREE_TYPE (expr)); | |
4ee9c684 | 2067 | if (t) |
2068 | return t; | |
2069 | } | |
2070 | } | |
2071 | ||
2072 | /* Otherwise we had an offset that we could not simplify. */ | |
2073 | return NULL_TREE; | |
2074 | } | |
2075 | ||
41511585 | 2076 | |
75a70cf9 | 2077 | /* A quaint feature extant in our address arithmetic is that there |
4ee9c684 | 2078 | can be hidden type changes here. The type of the result need |
2079 | not be the same as the type of the input pointer. | |
2080 | ||
2081 | What we're after here is an expression of the form | |
2082 | (T *)(&array + const) | |
75a70cf9 | 2083 | where array is OP0, const is OP1, RES_TYPE is T and |
2084 | the cast doesn't actually exist, but is implicit in the | |
0de36bdb | 2085 | type of the POINTER_PLUS_EXPR. We'd like to turn this into |
4ee9c684 | 2086 | &array[x] |
2087 | which may be able to propagate further. */ | |
2088 | ||
75a70cf9 | 2089 | tree |
2090 | maybe_fold_stmt_addition (tree res_type, tree op0, tree op1) | |
4ee9c684 | 2091 | { |
4ee9c684 | 2092 | tree ptd_type; |
2093 | tree t; | |
4ee9c684 | 2094 | |
4ee9c684 | 2095 | /* It had better be a constant. */ |
2096 | if (TREE_CODE (op1) != INTEGER_CST) | |
2097 | return NULL_TREE; | |
2098 | /* The first operand should be an ADDR_EXPR. */ | |
2099 | if (TREE_CODE (op0) != ADDR_EXPR) | |
2100 | return NULL_TREE; | |
2101 | op0 = TREE_OPERAND (op0, 0); | |
2102 | ||
2103 | /* If the first operand is an ARRAY_REF, expand it so that we can fold | |
2104 | the offset into it. */ | |
2105 | while (TREE_CODE (op0) == ARRAY_REF) | |
2106 | { | |
2107 | tree array_obj = TREE_OPERAND (op0, 0); | |
2108 | tree array_idx = TREE_OPERAND (op0, 1); | |
2109 | tree elt_type = TREE_TYPE (op0); | |
2110 | tree elt_size = TYPE_SIZE_UNIT (elt_type); | |
2111 | tree min_idx; | |
2112 | ||
2113 | if (TREE_CODE (array_idx) != INTEGER_CST) | |
2114 | break; | |
2115 | if (TREE_CODE (elt_size) != INTEGER_CST) | |
2116 | break; | |
2117 | ||
2118 | /* Un-bias the index by the min index of the array type. */ | |
2119 | min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj)); | |
2120 | if (min_idx) | |
2121 | { | |
2122 | min_idx = TYPE_MIN_VALUE (min_idx); | |
2123 | if (min_idx) | |
2124 | { | |
6374121b | 2125 | if (TREE_CODE (min_idx) != INTEGER_CST) |
2126 | break; | |
2127 | ||
535664e3 | 2128 | array_idx = fold_convert (TREE_TYPE (min_idx), array_idx); |
4ee9c684 | 2129 | if (!integer_zerop (min_idx)) |
2130 | array_idx = int_const_binop (MINUS_EXPR, array_idx, | |
2131 | min_idx, 0); | |
2132 | } | |
2133 | } | |
2134 | ||
2135 | /* Convert the index to a byte offset. */ | |
535664e3 | 2136 | array_idx = fold_convert (sizetype, array_idx); |
4ee9c684 | 2137 | array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0); |
2138 | ||
2139 | /* Update the operands for the next round, or for folding. */ | |
0de36bdb | 2140 | op1 = int_const_binop (PLUS_EXPR, |
4ee9c684 | 2141 | array_idx, op1, 0); |
4ee9c684 | 2142 | op0 = array_obj; |
2143 | } | |
2144 | ||
75a70cf9 | 2145 | ptd_type = TREE_TYPE (res_type); |
0b4a6afc | 2146 | /* If we want a pointer to void, reconstruct the reference from the |
2147 | array element type. A pointer to that can be trivially converted | |
2148 | to void *. This happens as we fold (void *)(ptr p+ off). */ | |
2149 | if (VOID_TYPE_P (ptd_type) | |
2150 | && TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE) | |
2151 | ptd_type = TREE_TYPE (TREE_TYPE (op0)); | |
4ee9c684 | 2152 | |
2153 | /* At which point we can try some of the same things as for indirects. */ | |
b7488229 | 2154 | t = maybe_fold_offset_to_array_ref (op0, op1, ptd_type, true); |
4ee9c684 | 2155 | if (!t) |
2156 | t = maybe_fold_offset_to_component_ref (TREE_TYPE (op0), op0, op1, | |
2157 | ptd_type, false); | |
2158 | if (t) | |
75a70cf9 | 2159 | t = build1 (ADDR_EXPR, res_type, t); |
4ee9c684 | 2160 | |
2161 | return t; | |
2162 | } | |
2163 | ||
0d759d9c | 2164 | /* For passing state through walk_tree into fold_stmt_r and its |
2165 | children. */ | |
2166 | ||
2167 | struct fold_stmt_r_data | |
2168 | { | |
75a70cf9 | 2169 | gimple stmt; |
add6ee5e | 2170 | bool *changed_p; |
2171 | bool *inside_addr_expr_p; | |
0d759d9c | 2172 | }; |
2173 | ||
4ee9c684 | 2174 | /* Subroutine of fold_stmt called via walk_tree. We perform several |
2175 | simplifications of EXPR_P, mostly having to do with pointer arithmetic. */ | |
2176 | ||
2177 | static tree | |
2178 | fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data) | |
2179 | { | |
75a70cf9 | 2180 | struct walk_stmt_info *wi = (struct walk_stmt_info *) data; |
2181 | struct fold_stmt_r_data *fold_stmt_r_data; | |
2182 | bool *inside_addr_expr_p; | |
2183 | bool *changed_p; | |
4ee9c684 | 2184 | tree expr = *expr_p, t; |
30fde358 | 2185 | bool volatile_p = TREE_THIS_VOLATILE (expr); |
4ee9c684 | 2186 | |
75a70cf9 | 2187 | fold_stmt_r_data = (struct fold_stmt_r_data *) wi->info; |
2188 | inside_addr_expr_p = fold_stmt_r_data->inside_addr_expr_p; | |
2189 | changed_p = fold_stmt_r_data->changed_p; | |
2190 | ||
4ee9c684 | 2191 | /* ??? It'd be nice if walk_tree had a pre-order option. */ |
2192 | switch (TREE_CODE (expr)) | |
2193 | { | |
2194 | case INDIRECT_REF: | |
2195 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
2196 | if (t) | |
2197 | return t; | |
2198 | *walk_subtrees = 0; | |
2199 | ||
2200 | t = maybe_fold_stmt_indirect (expr, TREE_OPERAND (expr, 0), | |
2201 | integer_zero_node); | |
4d444068 | 2202 | /* Avoid folding *"abc" = 5 into 'a' = 5. */ |
2203 | if (wi->is_lhs && t && TREE_CODE (t) == INTEGER_CST) | |
2204 | t = NULL_TREE; | |
8ac2d49b | 2205 | if (!t |
2206 | && TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR) | |
2207 | /* If we had a good reason for propagating the address here, | |
2208 | make sure we end up with valid gimple. See PR34989. */ | |
2209 | t = TREE_OPERAND (TREE_OPERAND (expr, 0), 0); | |
4ee9c684 | 2210 | break; |
2211 | ||
3b45913d | 2212 | case NOP_EXPR: |
2213 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
2214 | if (t) | |
2215 | return t; | |
2216 | *walk_subtrees = 0; | |
2217 | ||
2218 | if (POINTER_TYPE_P (TREE_TYPE (expr)) | |
50828ed8 | 2219 | && POINTER_TYPE_P (TREE_TYPE (TREE_TYPE (expr))) |
3b45913d | 2220 | && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0))) |
5768aeb3 | 2221 | && (t = maybe_fold_offset_to_address (TREE_OPERAND (expr, 0), |
2222 | integer_zero_node, | |
2223 | TREE_TYPE (TREE_TYPE (expr))))) | |
2224 | return t; | |
3b45913d | 2225 | break; |
2226 | ||
0d759d9c | 2227 | /* ??? Could handle more ARRAY_REFs here, as a variant of INDIRECT_REF. |
4ee9c684 | 2228 | We'd only want to bother decomposing an existing ARRAY_REF if |
2229 | the base array is found to have another offset contained within. | |
2230 | Otherwise we'd be wasting time. */ | |
0d759d9c | 2231 | case ARRAY_REF: |
2232 | /* If we are not processing expressions found within an | |
4d444068 | 2233 | ADDR_EXPR, then we can fold constant array references. |
2234 | Don't fold on LHS either, to avoid folding "abc"[0] = 5 | |
2235 | into 'a' = 5. */ | |
2236 | if (!*inside_addr_expr_p && !wi->is_lhs) | |
0d759d9c | 2237 | t = fold_read_from_constant_string (expr); |
2238 | else | |
2239 | t = NULL; | |
2240 | break; | |
4ee9c684 | 2241 | |
2242 | case ADDR_EXPR: | |
0d759d9c | 2243 | *inside_addr_expr_p = true; |
4ee9c684 | 2244 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); |
0d759d9c | 2245 | *inside_addr_expr_p = false; |
4ee9c684 | 2246 | if (t) |
2247 | return t; | |
2248 | *walk_subtrees = 0; | |
2249 | ||
c7d4e749 | 2250 | /* Make sure the value is properly considered constant, and so gets |
2251 | propagated as expected. */ | |
4ee9c684 | 2252 | if (*changed_p) |
750ad201 | 2253 | recompute_tree_invariant_for_addr_expr (expr); |
4ee9c684 | 2254 | return NULL_TREE; |
2255 | ||
4ee9c684 | 2256 | case COMPONENT_REF: |
2257 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
2258 | if (t) | |
2259 | return t; | |
2260 | *walk_subtrees = 0; | |
2261 | ||
504d3463 | 2262 | /* Make sure the FIELD_DECL is actually a field in the type on the lhs. |
2263 | We've already checked that the records are compatible, so we should | |
2264 | come up with a set of compatible fields. */ | |
2265 | { | |
2266 | tree expr_record = TREE_TYPE (TREE_OPERAND (expr, 0)); | |
2267 | tree expr_field = TREE_OPERAND (expr, 1); | |
2268 | ||
2269 | if (DECL_FIELD_CONTEXT (expr_field) != TYPE_MAIN_VARIANT (expr_record)) | |
2270 | { | |
2271 | expr_field = find_compatible_field (expr_record, expr_field); | |
2272 | TREE_OPERAND (expr, 1) = expr_field; | |
2273 | } | |
2274 | } | |
4ee9c684 | 2275 | break; |
2276 | ||
aed164c3 | 2277 | case TARGET_MEM_REF: |
2278 | t = maybe_fold_tmr (expr); | |
2279 | break; | |
2280 | ||
75a70cf9 | 2281 | case POINTER_PLUS_EXPR: |
2282 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
2283 | if (t) | |
2284 | return t; | |
2285 | t = walk_tree (&TREE_OPERAND (expr, 1), fold_stmt_r, data, NULL); | |
2286 | if (t) | |
2287 | return t; | |
2288 | *walk_subtrees = 0; | |
2289 | ||
2290 | t = maybe_fold_stmt_addition (TREE_TYPE (expr), | |
2291 | TREE_OPERAND (expr, 0), | |
2292 | TREE_OPERAND (expr, 1)); | |
2293 | break; | |
2294 | ||
bb8a9715 | 2295 | case COND_EXPR: |
2296 | if (COMPARISON_CLASS_P (TREE_OPERAND (expr, 0))) | |
2297 | { | |
2298 | tree op0 = TREE_OPERAND (expr, 0); | |
add6ee5e | 2299 | tree tem; |
2300 | bool set; | |
2301 | ||
2302 | fold_defer_overflow_warnings (); | |
2303 | tem = fold_binary (TREE_CODE (op0), TREE_TYPE (op0), | |
2304 | TREE_OPERAND (op0, 0), | |
2305 | TREE_OPERAND (op0, 1)); | |
75a70cf9 | 2306 | /* This is actually a conditional expression, not a GIMPLE |
2307 | conditional statement, however, the valid_gimple_rhs_p | |
2308 | test still applies. */ | |
2309 | set = tem && is_gimple_condexpr (tem) && valid_gimple_rhs_p (tem); | |
add6ee5e | 2310 | fold_undefer_overflow_warnings (set, fold_stmt_r_data->stmt, 0); |
2311 | if (set) | |
f2532264 | 2312 | { |
75a70cf9 | 2313 | COND_EXPR_COND (expr) = tem; |
2314 | t = expr; | |
f2532264 | 2315 | break; |
2316 | } | |
bb8a9715 | 2317 | } |
f2532264 | 2318 | return NULL_TREE; |
bb8a9715 | 2319 | |
4ee9c684 | 2320 | default: |
2321 | return NULL_TREE; | |
2322 | } | |
2323 | ||
2324 | if (t) | |
2325 | { | |
bcc7452f | 2326 | /* Preserve volatileness of the original expression. |
2327 | We can end up with a plain decl here which is shared | |
2328 | and we shouldn't mess with its flags. */ | |
2329 | if (!SSA_VAR_P (t)) | |
2330 | TREE_THIS_VOLATILE (t) = volatile_p; | |
4ee9c684 | 2331 | *expr_p = t; |
2332 | *changed_p = true; | |
2333 | } | |
2334 | ||
2335 | return NULL_TREE; | |
2336 | } | |
2337 | ||
0a39fd54 | 2338 | /* Return the string length, maximum string length or maximum value of |
2339 | ARG in LENGTH. | |
2340 | If ARG is an SSA name variable, follow its use-def chains. If LENGTH | |
2341 | is not NULL and, for TYPE == 0, its value is not equal to the length | |
2342 | we determine or if we are unable to determine the length or value, | |
2343 | return false. VISITED is a bitmap of visited variables. | |
2344 | TYPE is 0 if string length should be returned, 1 for maximum string | |
2345 | length and 2 for maximum value ARG can have. */ | |
4ee9c684 | 2346 | |
72648a0e | 2347 | static bool |
0a39fd54 | 2348 | get_maxval_strlen (tree arg, tree *length, bitmap visited, int type) |
4ee9c684 | 2349 | { |
75a70cf9 | 2350 | tree var, val; |
2351 | gimple def_stmt; | |
41511585 | 2352 | |
2353 | if (TREE_CODE (arg) != SSA_NAME) | |
72648a0e | 2354 | { |
ec0fa513 | 2355 | if (TREE_CODE (arg) == COND_EXPR) |
2356 | return get_maxval_strlen (COND_EXPR_THEN (arg), length, visited, type) | |
2357 | && get_maxval_strlen (COND_EXPR_ELSE (arg), length, visited, type); | |
0b4a6afc | 2358 | /* We can end up with &(*iftmp_1)[0] here as well, so handle it. */ |
2359 | else if (TREE_CODE (arg) == ADDR_EXPR | |
2360 | && TREE_CODE (TREE_OPERAND (arg, 0)) == ARRAY_REF | |
2361 | && integer_zerop (TREE_OPERAND (TREE_OPERAND (arg, 0), 1))) | |
2362 | { | |
2363 | tree aop0 = TREE_OPERAND (TREE_OPERAND (arg, 0), 0); | |
2364 | if (TREE_CODE (aop0) == INDIRECT_REF | |
2365 | && TREE_CODE (TREE_OPERAND (aop0, 0)) == SSA_NAME) | |
2366 | return get_maxval_strlen (TREE_OPERAND (aop0, 0), | |
2367 | length, visited, type); | |
2368 | } | |
ec0fa513 | 2369 | |
0a39fd54 | 2370 | if (type == 2) |
2371 | { | |
2372 | val = arg; | |
2373 | if (TREE_CODE (val) != INTEGER_CST | |
2374 | || tree_int_cst_sgn (val) < 0) | |
2375 | return false; | |
2376 | } | |
2377 | else | |
2378 | val = c_strlen (arg, 1); | |
41511585 | 2379 | if (!val) |
72648a0e | 2380 | return false; |
e37235f0 | 2381 | |
0a39fd54 | 2382 | if (*length) |
2383 | { | |
2384 | if (type > 0) | |
2385 | { | |
2386 | if (TREE_CODE (*length) != INTEGER_CST | |
2387 | || TREE_CODE (val) != INTEGER_CST) | |
2388 | return false; | |
2389 | ||
2390 | if (tree_int_cst_lt (*length, val)) | |
2391 | *length = val; | |
2392 | return true; | |
2393 | } | |
2394 | else if (simple_cst_equal (val, *length) != 1) | |
2395 | return false; | |
2396 | } | |
4ee9c684 | 2397 | |
41511585 | 2398 | *length = val; |
2399 | return true; | |
4ee9c684 | 2400 | } |
72648a0e | 2401 | |
41511585 | 2402 | /* If we were already here, break the infinite cycle. */ |
2403 | if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg))) | |
2404 | return true; | |
2405 | bitmap_set_bit (visited, SSA_NAME_VERSION (arg)); | |
2406 | ||
2407 | var = arg; | |
2408 | def_stmt = SSA_NAME_DEF_STMT (var); | |
4ee9c684 | 2409 | |
75a70cf9 | 2410 | switch (gimple_code (def_stmt)) |
2411 | { | |
2412 | case GIMPLE_ASSIGN: | |
2413 | /* The RHS of the statement defining VAR must either have a | |
2414 | constant length or come from another SSA_NAME with a constant | |
2415 | length. */ | |
2416 | if (gimple_assign_single_p (def_stmt) | |
2417 | || gimple_assign_unary_nop_p (def_stmt)) | |
2418 | { | |
2419 | tree rhs = gimple_assign_rhs1 (def_stmt); | |
2420 | return get_maxval_strlen (rhs, length, visited, type); | |
2421 | } | |
2422 | return false; | |
2423 | ||
2424 | case GIMPLE_PHI: | |
41511585 | 2425 | { |
2426 | /* All the arguments of the PHI node must have the same constant | |
2427 | length. */ | |
75a70cf9 | 2428 | unsigned i; |
2429 | ||
2430 | for (i = 0; i < gimple_phi_num_args (def_stmt); i++) | |
2431 | { | |
2432 | tree arg = gimple_phi_arg (def_stmt, i)->def; | |
2433 | ||
2434 | /* If this PHI has itself as an argument, we cannot | |
2435 | determine the string length of this argument. However, | |
2436 | if we can find a constant string length for the other | |
2437 | PHI args then we can still be sure that this is a | |
2438 | constant string length. So be optimistic and just | |
2439 | continue with the next argument. */ | |
2440 | if (arg == gimple_phi_result (def_stmt)) | |
2441 | continue; | |
2442 | ||
2443 | if (!get_maxval_strlen (arg, length, visited, type)) | |
2444 | return false; | |
2445 | } | |
2446 | } | |
2447 | return true; | |
4ee9c684 | 2448 | |
41511585 | 2449 | default: |
75a70cf9 | 2450 | return false; |
4ee9c684 | 2451 | } |
4ee9c684 | 2452 | } |
2453 | ||
2454 | ||
75a70cf9 | 2455 | /* Fold builtin call in statement STMT. Returns a simplified tree. |
2456 | We may return a non-constant expression, including another call | |
2457 | to a different function and with different arguments, e.g., | |
2458 | substituting memcpy for strcpy when the string length is known. | |
2459 | Note that some builtins expand into inline code that may not | |
2460 | be valid in GIMPLE. Callers must take care. */ | |
4ee9c684 | 2461 | |
2462 | static tree | |
75a70cf9 | 2463 | ccp_fold_builtin (gimple stmt) |
4ee9c684 | 2464 | { |
0a39fd54 | 2465 | tree result, val[3]; |
c2f47e15 | 2466 | tree callee, a; |
be9f921e | 2467 | int arg_idx, type; |
f0613857 | 2468 | bitmap visited; |
2469 | bool ignore; | |
c2f47e15 | 2470 | int nargs; |
4ee9c684 | 2471 | |
75a70cf9 | 2472 | gcc_assert (is_gimple_call (stmt)); |
2473 | ||
2474 | ignore = (gimple_call_lhs (stmt) == NULL); | |
4ee9c684 | 2475 | |
2476 | /* First try the generic builtin folder. If that succeeds, return the | |
2477 | result directly. */ | |
75a70cf9 | 2478 | result = fold_call_stmt (stmt, ignore); |
4ee9c684 | 2479 | if (result) |
0a39fd54 | 2480 | { |
2481 | if (ignore) | |
2482 | STRIP_NOPS (result); | |
2483 | return result; | |
2484 | } | |
f0613857 | 2485 | |
2486 | /* Ignore MD builtins. */ | |
75a70cf9 | 2487 | callee = gimple_call_fndecl (stmt); |
f0613857 | 2488 | if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD) |
2489 | return NULL_TREE; | |
4ee9c684 | 2490 | |
2491 | /* If the builtin could not be folded, and it has no argument list, | |
2492 | we're done. */ | |
75a70cf9 | 2493 | nargs = gimple_call_num_args (stmt); |
c2f47e15 | 2494 | if (nargs == 0) |
4ee9c684 | 2495 | return NULL_TREE; |
2496 | ||
2497 | /* Limit the work only for builtins we know how to simplify. */ | |
2498 | switch (DECL_FUNCTION_CODE (callee)) | |
2499 | { | |
2500 | case BUILT_IN_STRLEN: | |
2501 | case BUILT_IN_FPUTS: | |
2502 | case BUILT_IN_FPUTS_UNLOCKED: | |
be9f921e | 2503 | arg_idx = 0; |
0a39fd54 | 2504 | type = 0; |
4ee9c684 | 2505 | break; |
2506 | case BUILT_IN_STRCPY: | |
2507 | case BUILT_IN_STRNCPY: | |
be9f921e | 2508 | arg_idx = 1; |
0a39fd54 | 2509 | type = 0; |
2510 | break; | |
2511 | case BUILT_IN_MEMCPY_CHK: | |
2512 | case BUILT_IN_MEMPCPY_CHK: | |
2513 | case BUILT_IN_MEMMOVE_CHK: | |
2514 | case BUILT_IN_MEMSET_CHK: | |
2515 | case BUILT_IN_STRNCPY_CHK: | |
be9f921e | 2516 | arg_idx = 2; |
0a39fd54 | 2517 | type = 2; |
2518 | break; | |
2519 | case BUILT_IN_STRCPY_CHK: | |
2520 | case BUILT_IN_STPCPY_CHK: | |
be9f921e | 2521 | arg_idx = 1; |
0a39fd54 | 2522 | type = 1; |
2523 | break; | |
2524 | case BUILT_IN_SNPRINTF_CHK: | |
2525 | case BUILT_IN_VSNPRINTF_CHK: | |
be9f921e | 2526 | arg_idx = 1; |
0a39fd54 | 2527 | type = 2; |
4ee9c684 | 2528 | break; |
2529 | default: | |
2530 | return NULL_TREE; | |
2531 | } | |
2532 | ||
54807c88 | 2533 | if (arg_idx >= nargs) |
2534 | return NULL_TREE; | |
2535 | ||
4ee9c684 | 2536 | /* Try to use the dataflow information gathered by the CCP process. */ |
27335ffd | 2537 | visited = BITMAP_ALLOC (NULL); |
be9f921e | 2538 | bitmap_clear (visited); |
4ee9c684 | 2539 | |
0a39fd54 | 2540 | memset (val, 0, sizeof (val)); |
be9f921e | 2541 | a = gimple_call_arg (stmt, arg_idx); |
2542 | if (!get_maxval_strlen (a, &val[arg_idx], visited, type)) | |
2543 | val[arg_idx] = NULL_TREE; | |
4ee9c684 | 2544 | |
27335ffd | 2545 | BITMAP_FREE (visited); |
4ee9c684 | 2546 | |
f0613857 | 2547 | result = NULL_TREE; |
4ee9c684 | 2548 | switch (DECL_FUNCTION_CODE (callee)) |
2549 | { | |
2550 | case BUILT_IN_STRLEN: | |
54807c88 | 2551 | if (val[0] && nargs == 1) |
4ee9c684 | 2552 | { |
75a70cf9 | 2553 | tree new_val = |
2554 | fold_convert (TREE_TYPE (gimple_call_lhs (stmt)), val[0]); | |
4ee9c684 | 2555 | |
2556 | /* If the result is not a valid gimple value, or not a cast | |
2557 | of a valid gimple value, then we can not use the result. */ | |
f0d6e81c | 2558 | if (is_gimple_val (new_val) |
2559 | || (is_gimple_cast (new_val) | |
2560 | && is_gimple_val (TREE_OPERAND (new_val, 0)))) | |
2561 | return new_val; | |
4ee9c684 | 2562 | } |
f0613857 | 2563 | break; |
2564 | ||
4ee9c684 | 2565 | case BUILT_IN_STRCPY: |
c2f47e15 | 2566 | if (val[1] && is_gimple_val (val[1]) && nargs == 2) |
2567 | result = fold_builtin_strcpy (callee, | |
75a70cf9 | 2568 | gimple_call_arg (stmt, 0), |
2569 | gimple_call_arg (stmt, 1), | |
c2f47e15 | 2570 | val[1]); |
f0613857 | 2571 | break; |
2572 | ||
4ee9c684 | 2573 | case BUILT_IN_STRNCPY: |
c2f47e15 | 2574 | if (val[1] && is_gimple_val (val[1]) && nargs == 3) |
2575 | result = fold_builtin_strncpy (callee, | |
75a70cf9 | 2576 | gimple_call_arg (stmt, 0), |
2577 | gimple_call_arg (stmt, 1), | |
2578 | gimple_call_arg (stmt, 2), | |
c2f47e15 | 2579 | val[1]); |
f0613857 | 2580 | break; |
2581 | ||
4ee9c684 | 2582 | case BUILT_IN_FPUTS: |
54807c88 | 2583 | if (nargs == 2) |
2584 | result = fold_builtin_fputs (gimple_call_arg (stmt, 0), | |
2585 | gimple_call_arg (stmt, 1), | |
2586 | ignore, false, val[0]); | |
f0613857 | 2587 | break; |
2588 | ||
4ee9c684 | 2589 | case BUILT_IN_FPUTS_UNLOCKED: |
54807c88 | 2590 | if (nargs == 2) |
2591 | result = fold_builtin_fputs (gimple_call_arg (stmt, 0), | |
2592 | gimple_call_arg (stmt, 1), | |
2593 | ignore, true, val[0]); | |
0a39fd54 | 2594 | break; |
2595 | ||
2596 | case BUILT_IN_MEMCPY_CHK: | |
2597 | case BUILT_IN_MEMPCPY_CHK: | |
2598 | case BUILT_IN_MEMMOVE_CHK: | |
2599 | case BUILT_IN_MEMSET_CHK: | |
54807c88 | 2600 | if (val[2] && is_gimple_val (val[2]) && nargs == 4) |
c2f47e15 | 2601 | result = fold_builtin_memory_chk (callee, |
75a70cf9 | 2602 | gimple_call_arg (stmt, 0), |
2603 | gimple_call_arg (stmt, 1), | |
2604 | gimple_call_arg (stmt, 2), | |
2605 | gimple_call_arg (stmt, 3), | |
c2f47e15 | 2606 | val[2], ignore, |
0a39fd54 | 2607 | DECL_FUNCTION_CODE (callee)); |
2608 | break; | |
2609 | ||
2610 | case BUILT_IN_STRCPY_CHK: | |
2611 | case BUILT_IN_STPCPY_CHK: | |
54807c88 | 2612 | if (val[1] && is_gimple_val (val[1]) && nargs == 3) |
c2f47e15 | 2613 | result = fold_builtin_stxcpy_chk (callee, |
75a70cf9 | 2614 | gimple_call_arg (stmt, 0), |
2615 | gimple_call_arg (stmt, 1), | |
2616 | gimple_call_arg (stmt, 2), | |
c2f47e15 | 2617 | val[1], ignore, |
0a39fd54 | 2618 | DECL_FUNCTION_CODE (callee)); |
2619 | break; | |
2620 | ||
2621 | case BUILT_IN_STRNCPY_CHK: | |
54807c88 | 2622 | if (val[2] && is_gimple_val (val[2]) && nargs == 4) |
75a70cf9 | 2623 | result = fold_builtin_strncpy_chk (gimple_call_arg (stmt, 0), |
2624 | gimple_call_arg (stmt, 1), | |
2625 | gimple_call_arg (stmt, 2), | |
2626 | gimple_call_arg (stmt, 3), | |
c2f47e15 | 2627 | val[2]); |
0a39fd54 | 2628 | break; |
2629 | ||
2630 | case BUILT_IN_SNPRINTF_CHK: | |
2631 | case BUILT_IN_VSNPRINTF_CHK: | |
2632 | if (val[1] && is_gimple_val (val[1])) | |
75a70cf9 | 2633 | result = gimple_fold_builtin_snprintf_chk (stmt, val[1], |
2634 | DECL_FUNCTION_CODE (callee)); | |
f0613857 | 2635 | break; |
4ee9c684 | 2636 | |
2637 | default: | |
8c0963c4 | 2638 | gcc_unreachable (); |
4ee9c684 | 2639 | } |
2640 | ||
f0613857 | 2641 | if (result && ignore) |
db97ad41 | 2642 | result = fold_ignored_result (result); |
f0613857 | 2643 | return result; |
4ee9c684 | 2644 | } |
2645 | ||
75a70cf9 | 2646 | /* Attempt to fold an assignment statement pointed-to by SI. Returns a |
2647 | replacement rhs for the statement or NULL_TREE if no simplification | |
2648 | could be made. It is assumed that the operands have been previously | |
2649 | folded. */ | |
2650 | ||
2651 | static tree | |
2652 | fold_gimple_assign (gimple_stmt_iterator *si) | |
2653 | { | |
2654 | gimple stmt = gsi_stmt (*si); | |
2655 | enum tree_code subcode = gimple_assign_rhs_code (stmt); | |
2656 | ||
2657 | tree result = NULL; | |
2658 | ||
2659 | switch (get_gimple_rhs_class (subcode)) | |
2660 | { | |
2661 | case GIMPLE_SINGLE_RHS: | |
2662 | { | |
2663 | tree rhs = gimple_assign_rhs1 (stmt); | |
2664 | ||
2665 | /* Try to fold a conditional expression. */ | |
2666 | if (TREE_CODE (rhs) == COND_EXPR) | |
2667 | { | |
2668 | tree temp = fold (COND_EXPR_COND (rhs)); | |
2669 | if (temp != COND_EXPR_COND (rhs)) | |
2670 | result = fold_build3 (COND_EXPR, TREE_TYPE (rhs), temp, | |
2671 | COND_EXPR_THEN (rhs), COND_EXPR_ELSE (rhs)); | |
2672 | } | |
2673 | ||
2674 | /* If we couldn't fold the RHS, hand over to the generic | |
2675 | fold routines. */ | |
2676 | if (result == NULL_TREE) | |
2677 | result = fold (rhs); | |
2678 | ||
2679 | /* Strip away useless type conversions. Both the NON_LVALUE_EXPR | |
2680 | that may have been added by fold, and "useless" type | |
2681 | conversions that might now be apparent due to propagation. */ | |
2682 | STRIP_USELESS_TYPE_CONVERSION (result); | |
2683 | ||
2684 | if (result != rhs && valid_gimple_rhs_p (result)) | |
2685 | return result; | |
2686 | else | |
2687 | /* It is possible that fold_stmt_r simplified the RHS. | |
2688 | Make sure that the subcode of this statement still | |
2689 | reflects the principal operator of the rhs operand. */ | |
2690 | return rhs; | |
2691 | } | |
2692 | break; | |
2693 | ||
2694 | case GIMPLE_UNARY_RHS: | |
f1fb2997 | 2695 | { |
2696 | tree rhs = gimple_assign_rhs1 (stmt); | |
75a70cf9 | 2697 | |
f1fb2997 | 2698 | result = fold_unary (subcode, gimple_expr_type (stmt), rhs); |
2699 | if (result) | |
2700 | { | |
2701 | /* If the operation was a conversion do _not_ mark a | |
2702 | resulting constant with TREE_OVERFLOW if the original | |
2703 | constant was not. These conversions have implementation | |
2704 | defined behavior and retaining the TREE_OVERFLOW flag | |
2705 | here would confuse later passes such as VRP. */ | |
2706 | if (CONVERT_EXPR_CODE_P (subcode) | |
2707 | && TREE_CODE (result) == INTEGER_CST | |
2708 | && TREE_CODE (rhs) == INTEGER_CST) | |
2709 | TREE_OVERFLOW (result) = TREE_OVERFLOW (rhs); | |
2710 | ||
2711 | STRIP_USELESS_TYPE_CONVERSION (result); | |
2712 | if (valid_gimple_rhs_p (result)) | |
2713 | return result; | |
2714 | } | |
2715 | else if (CONVERT_EXPR_CODE_P (subcode) | |
2716 | && POINTER_TYPE_P (gimple_expr_type (stmt)) | |
2717 | && POINTER_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt)))) | |
2718 | { | |
2719 | tree type = gimple_expr_type (stmt); | |
2720 | tree t = maybe_fold_offset_to_address (gimple_assign_rhs1 (stmt), | |
2721 | integer_zero_node, type); | |
2722 | if (t) | |
2723 | return t; | |
2724 | } | |
2725 | } | |
75a70cf9 | 2726 | break; |
2727 | ||
2728 | case GIMPLE_BINARY_RHS: | |
2729 | /* Try to fold pointer addition. */ | |
2730 | if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR) | |
93f3673b | 2731 | { |
2732 | tree type = TREE_TYPE (gimple_assign_rhs1 (stmt)); | |
2733 | if (TREE_CODE (TREE_TYPE (type)) == ARRAY_TYPE) | |
2734 | { | |
2735 | type = build_pointer_type (TREE_TYPE (TREE_TYPE (type))); | |
2736 | if (!useless_type_conversion_p | |
2737 | (TREE_TYPE (gimple_assign_lhs (stmt)), type)) | |
2738 | type = TREE_TYPE (gimple_assign_rhs1 (stmt)); | |
2739 | } | |
2740 | result = maybe_fold_stmt_addition (type, | |
2741 | gimple_assign_rhs1 (stmt), | |
2742 | gimple_assign_rhs2 (stmt)); | |
2743 | } | |
75a70cf9 | 2744 | |
2745 | if (!result) | |
2746 | result = fold_binary (subcode, | |
2747 | TREE_TYPE (gimple_assign_lhs (stmt)), | |
2748 | gimple_assign_rhs1 (stmt), | |
2749 | gimple_assign_rhs2 (stmt)); | |
2750 | ||
2751 | if (result) | |
2752 | { | |
2753 | STRIP_USELESS_TYPE_CONVERSION (result); | |
2754 | if (valid_gimple_rhs_p (result)) | |
2755 | return result; | |
ec3753d0 | 2756 | |
2757 | /* Fold might have produced non-GIMPLE, so if we trust it blindly | |
2758 | we lose canonicalization opportunities. Do not go again | |
2759 | through fold here though, or the same non-GIMPLE will be | |
2760 | produced. */ | |
2761 | if (commutative_tree_code (subcode) | |
2762 | && tree_swap_operands_p (gimple_assign_rhs1 (stmt), | |
2763 | gimple_assign_rhs2 (stmt), false)) | |
2764 | return build2 (subcode, TREE_TYPE (gimple_assign_lhs (stmt)), | |
2765 | gimple_assign_rhs2 (stmt), | |
2766 | gimple_assign_rhs1 (stmt)); | |
75a70cf9 | 2767 | } |
2768 | break; | |
2769 | ||
2770 | case GIMPLE_INVALID_RHS: | |
2771 | gcc_unreachable (); | |
2772 | } | |
2773 | ||
2774 | return NULL_TREE; | |
2775 | } | |
2776 | ||
2777 | /* Attempt to fold a conditional statement. Return true if any changes were | |
2778 | made. We only attempt to fold the condition expression, and do not perform | |
2779 | any transformation that would require alteration of the cfg. It is | |
2780 | assumed that the operands have been previously folded. */ | |
2781 | ||
2782 | static bool | |
2783 | fold_gimple_cond (gimple stmt) | |
2784 | { | |
2785 | tree result = fold_binary (gimple_cond_code (stmt), | |
2786 | boolean_type_node, | |
2787 | gimple_cond_lhs (stmt), | |
2788 | gimple_cond_rhs (stmt)); | |
2789 | ||
2790 | if (result) | |
2791 | { | |
2792 | STRIP_USELESS_TYPE_CONVERSION (result); | |
2793 | if (is_gimple_condexpr (result) && valid_gimple_rhs_p (result)) | |
2794 | { | |
2795 | gimple_cond_set_condition_from_tree (stmt, result); | |
2796 | return true; | |
2797 | } | |
2798 | } | |
2799 | ||
2800 | return false; | |
2801 | } | |
2802 | ||
2803 | ||
2804 | /* Attempt to fold a call statement referenced by the statement iterator GSI. | |
2805 | The statement may be replaced by another statement, e.g., if the call | |
2806 | simplifies to a constant value. Return true if any changes were made. | |
2807 | It is assumed that the operands have been previously folded. */ | |
2808 | ||
2809 | static bool | |
2810 | fold_gimple_call (gimple_stmt_iterator *gsi) | |
2811 | { | |
2812 | gimple stmt = gsi_stmt (*gsi); | |
2813 | ||
2814 | tree callee = gimple_call_fndecl (stmt); | |
2815 | ||
2816 | /* Check for builtins that CCP can handle using information not | |
2817 | available in the generic fold routines. */ | |
2818 | if (callee && DECL_BUILT_IN (callee)) | |
2819 | { | |
2820 | tree result = ccp_fold_builtin (stmt); | |
2821 | ||
2822 | if (result) | |
2823 | return update_call_from_tree (gsi, result); | |
2824 | } | |
2825 | else | |
2826 | { | |
2827 | /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve | |
2828 | here are when we've propagated the address of a decl into the | |
2829 | object slot. */ | |
2830 | /* ??? Should perhaps do this in fold proper. However, doing it | |
2831 | there requires that we create a new CALL_EXPR, and that requires | |
2832 | copying EH region info to the new node. Easier to just do it | |
2833 | here where we can just smash the call operand. */ | |
2834 | /* ??? Is there a good reason not to do this in fold_stmt_inplace? */ | |
2835 | callee = gimple_call_fn (stmt); | |
2836 | if (TREE_CODE (callee) == OBJ_TYPE_REF | |
2837 | && lang_hooks.fold_obj_type_ref | |
2838 | && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR | |
2839 | && DECL_P (TREE_OPERAND | |
2840 | (OBJ_TYPE_REF_OBJECT (callee), 0))) | |
2841 | { | |
2842 | tree t; | |
2843 | ||
2844 | /* ??? Caution: Broken ADDR_EXPR semantics means that | |
2845 | looking at the type of the operand of the addr_expr | |
2846 | can yield an array type. See silly exception in | |
2847 | check_pointer_types_r. */ | |
2848 | t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee))); | |
2849 | t = lang_hooks.fold_obj_type_ref (callee, t); | |
2850 | if (t) | |
2851 | { | |
2852 | gimple_call_set_fn (stmt, t); | |
2853 | return true; | |
2854 | } | |
2855 | } | |
2856 | } | |
2857 | ||
2858 | return false; | |
2859 | } | |
4ee9c684 | 2860 | |
75a70cf9 | 2861 | /* Fold the statement pointed to by GSI. In some cases, this function may |
41511585 | 2862 | replace the whole statement with a new one. Returns true iff folding |
2863 | makes any changes. */ | |
4ee9c684 | 2864 | |
41511585 | 2865 | bool |
75a70cf9 | 2866 | fold_stmt (gimple_stmt_iterator *gsi) |
4ee9c684 | 2867 | { |
75a70cf9 | 2868 | tree res; |
0d759d9c | 2869 | struct fold_stmt_r_data fold_stmt_r_data; |
75a70cf9 | 2870 | struct walk_stmt_info wi; |
2871 | ||
41511585 | 2872 | bool changed = false; |
0d759d9c | 2873 | bool inside_addr_expr = false; |
2874 | ||
75a70cf9 | 2875 | gimple stmt = gsi_stmt (*gsi); |
add6ee5e | 2876 | |
2877 | fold_stmt_r_data.stmt = stmt; | |
0d759d9c | 2878 | fold_stmt_r_data.changed_p = &changed; |
2879 | fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr; | |
4ee9c684 | 2880 | |
75a70cf9 | 2881 | memset (&wi, 0, sizeof (wi)); |
2882 | wi.info = &fold_stmt_r_data; | |
4ee9c684 | 2883 | |
75a70cf9 | 2884 | /* Fold the individual operands. |
2885 | For example, fold instances of *&VAR into VAR, etc. */ | |
2886 | res = walk_gimple_op (stmt, fold_stmt_r, &wi); | |
2887 | gcc_assert (!res); | |
4ee9c684 | 2888 | |
75a70cf9 | 2889 | /* Fold the main computation performed by the statement. */ |
2890 | switch (gimple_code (stmt)) | |
4ee9c684 | 2891 | { |
75a70cf9 | 2892 | case GIMPLE_ASSIGN: |
2893 | { | |
2894 | tree new_rhs = fold_gimple_assign (gsi); | |
2895 | if (new_rhs != NULL_TREE) | |
2896 | { | |
2897 | gimple_assign_set_rhs_from_tree (gsi, new_rhs); | |
2898 | changed = true; | |
2899 | } | |
2900 | stmt = gsi_stmt (*gsi); | |
2901 | break; | |
2902 | } | |
2903 | case GIMPLE_COND: | |
2904 | changed |= fold_gimple_cond (stmt); | |
2905 | break; | |
2906 | case GIMPLE_CALL: | |
2907 | /* The entire statement may be replaced in this case. */ | |
2908 | changed |= fold_gimple_call (gsi); | |
2909 | break; | |
e77b8618 | 2910 | |
75a70cf9 | 2911 | default: |
2912 | return changed; | |
2913 | break; | |
ec0fa513 | 2914 | } |
4ee9c684 | 2915 | |
41511585 | 2916 | return changed; |
4ee9c684 | 2917 | } |
2918 | ||
8171a1dd | 2919 | /* Perform the minimal folding on statement STMT. Only operations like |
2920 | *&x created by constant propagation are handled. The statement cannot | |
75a70cf9 | 2921 | be replaced with a new one. Return true if the statement was |
2922 | changed, false otherwise. */ | |
8171a1dd | 2923 | |
2924 | bool | |
75a70cf9 | 2925 | fold_stmt_inplace (gimple stmt) |
8171a1dd | 2926 | { |
75a70cf9 | 2927 | tree res; |
0d759d9c | 2928 | struct fold_stmt_r_data fold_stmt_r_data; |
75a70cf9 | 2929 | struct walk_stmt_info wi; |
2930 | gimple_stmt_iterator si; | |
2931 | ||
8171a1dd | 2932 | bool changed = false; |
0d759d9c | 2933 | bool inside_addr_expr = false; |
2934 | ||
add6ee5e | 2935 | fold_stmt_r_data.stmt = stmt; |
0d759d9c | 2936 | fold_stmt_r_data.changed_p = &changed; |
2937 | fold_stmt_r_data.inside_addr_expr_p = &inside_addr_expr; | |
8171a1dd | 2938 | |
75a70cf9 | 2939 | memset (&wi, 0, sizeof (wi)); |
2940 | wi.info = &fold_stmt_r_data; | |
2941 | ||
2942 | /* Fold the individual operands. | |
2943 | For example, fold instances of *&VAR into VAR, etc. | |
8171a1dd | 2944 | |
75a70cf9 | 2945 | It appears that, at one time, maybe_fold_stmt_indirect |
2946 | would cause the walk to return non-null in order to | |
2947 | signal that the entire statement should be replaced with | |
2948 | a call to _builtin_trap. This functionality is currently | |
2949 | disabled, as noted in a FIXME, and cannot be supported here. */ | |
2950 | res = walk_gimple_op (stmt, fold_stmt_r, &wi); | |
2951 | gcc_assert (!res); | |
8171a1dd | 2952 | |
75a70cf9 | 2953 | /* Fold the main computation performed by the statement. */ |
2954 | switch (gimple_code (stmt)) | |
2955 | { | |
2956 | case GIMPLE_ASSIGN: | |
2957 | { | |
2958 | unsigned old_num_ops; | |
2959 | tree new_rhs; | |
2960 | old_num_ops = gimple_num_ops (stmt); | |
2961 | si = gsi_for_stmt (stmt); | |
2962 | new_rhs = fold_gimple_assign (&si); | |
2963 | if (new_rhs != NULL_TREE | |
2964 | && get_gimple_rhs_num_ops (TREE_CODE (new_rhs)) < old_num_ops) | |
2965 | { | |
2966 | gimple_assign_set_rhs_from_tree (&si, new_rhs); | |
2967 | changed = true; | |
2968 | } | |
2969 | gcc_assert (gsi_stmt (si) == stmt); | |
2970 | break; | |
2971 | } | |
2972 | case GIMPLE_COND: | |
2973 | changed |= fold_gimple_cond (stmt); | |
2974 | break; | |
8171a1dd | 2975 | |
75a70cf9 | 2976 | default: |
2977 | break; | |
2978 | } | |
8171a1dd | 2979 | |
2980 | return changed; | |
2981 | } | |
75a70cf9 | 2982 | |
bdd0e199 | 2983 | /* Try to optimize out __builtin_stack_restore. Optimize it out |
2984 | if there is another __builtin_stack_restore in the same basic | |
2985 | block and no calls or ASM_EXPRs are in between, or if this block's | |
2986 | only outgoing edge is to EXIT_BLOCK and there are no calls or | |
2987 | ASM_EXPRs after this __builtin_stack_restore. */ | |
2988 | ||
2989 | static tree | |
75a70cf9 | 2990 | optimize_stack_restore (gimple_stmt_iterator i) |
bdd0e199 | 2991 | { |
75a70cf9 | 2992 | tree callee, rhs; |
2993 | gimple stmt, stack_save; | |
2994 | gimple_stmt_iterator stack_save_gsi; | |
2995 | ||
2996 | basic_block bb = gsi_bb (i); | |
2997 | gimple call = gsi_stmt (i); | |
bdd0e199 | 2998 | |
75a70cf9 | 2999 | if (gimple_code (call) != GIMPLE_CALL |
3000 | || gimple_call_num_args (call) != 1 | |
3001 | || TREE_CODE (gimple_call_arg (call, 0)) != SSA_NAME | |
3002 | || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call, 0)))) | |
bdd0e199 | 3003 | return NULL_TREE; |
3004 | ||
75a70cf9 | 3005 | for (gsi_next (&i); !gsi_end_p (i); gsi_next (&i)) |
bdd0e199 | 3006 | { |
75a70cf9 | 3007 | stmt = gsi_stmt (i); |
3008 | if (gimple_code (stmt) == GIMPLE_ASM) | |
bdd0e199 | 3009 | return NULL_TREE; |
75a70cf9 | 3010 | if (gimple_code (stmt) != GIMPLE_CALL) |
bdd0e199 | 3011 | continue; |
3012 | ||
75a70cf9 | 3013 | callee = gimple_call_fndecl (stmt); |
bdd0e199 | 3014 | if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL) |
3015 | return NULL_TREE; | |
3016 | ||
3017 | if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE) | |
3018 | break; | |
3019 | } | |
3020 | ||
75a70cf9 | 3021 | if (gsi_end_p (i) |
bdd0e199 | 3022 | && (! single_succ_p (bb) |
3023 | || single_succ_edge (bb)->dest != EXIT_BLOCK_PTR)) | |
3024 | return NULL_TREE; | |
3025 | ||
75a70cf9 | 3026 | stack_save = SSA_NAME_DEF_STMT (gimple_call_arg (call, 0)); |
3027 | if (gimple_code (stack_save) != GIMPLE_CALL | |
3028 | || gimple_call_lhs (stack_save) != gimple_call_arg (call, 0) | |
3029 | || stmt_could_throw_p (stack_save) | |
3030 | || !has_single_use (gimple_call_arg (call, 0))) | |
bdd0e199 | 3031 | return NULL_TREE; |
3032 | ||
75a70cf9 | 3033 | callee = gimple_call_fndecl (stack_save); |
bdd0e199 | 3034 | if (!callee |
3035 | || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL | |
3036 | || DECL_FUNCTION_CODE (callee) != BUILT_IN_STACK_SAVE | |
75a70cf9 | 3037 | || gimple_call_num_args (stack_save) != 0) |
bdd0e199 | 3038 | return NULL_TREE; |
3039 | ||
75a70cf9 | 3040 | stack_save_gsi = gsi_for_stmt (stack_save); |
3041 | push_stmt_changes (gsi_stmt_ptr (&stack_save_gsi)); | |
3042 | rhs = build_int_cst (TREE_TYPE (gimple_call_arg (call, 0)), 0); | |
3043 | if (!update_call_from_tree (&stack_save_gsi, rhs)) | |
bdd0e199 | 3044 | { |
75a70cf9 | 3045 | discard_stmt_changes (gsi_stmt_ptr (&stack_save_gsi)); |
bdd0e199 | 3046 | return NULL_TREE; |
3047 | } | |
75a70cf9 | 3048 | pop_stmt_changes (gsi_stmt_ptr (&stack_save_gsi)); |
bdd0e199 | 3049 | |
75a70cf9 | 3050 | /* No effect, so the statement will be deleted. */ |
bdd0e199 | 3051 | return integer_zero_node; |
3052 | } | |
75a70cf9 | 3053 | |
8a58ed0a | 3054 | /* If va_list type is a simple pointer and nothing special is needed, |
3055 | optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0), | |
3056 | __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple | |
3057 | pointer assignment. */ | |
3058 | ||
3059 | static tree | |
75a70cf9 | 3060 | optimize_stdarg_builtin (gimple call) |
8a58ed0a | 3061 | { |
5f57a8b1 | 3062 | tree callee, lhs, rhs, cfun_va_list; |
8a58ed0a | 3063 | bool va_list_simple_ptr; |
3064 | ||
75a70cf9 | 3065 | if (gimple_code (call) != GIMPLE_CALL) |
8a58ed0a | 3066 | return NULL_TREE; |
3067 | ||
75a70cf9 | 3068 | callee = gimple_call_fndecl (call); |
5f57a8b1 | 3069 | |
3070 | cfun_va_list = targetm.fn_abi_va_list (callee); | |
3071 | va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list) | |
3072 | && (TREE_TYPE (cfun_va_list) == void_type_node | |
3073 | || TREE_TYPE (cfun_va_list) == char_type_node); | |
3074 | ||
8a58ed0a | 3075 | switch (DECL_FUNCTION_CODE (callee)) |
3076 | { | |
3077 | case BUILT_IN_VA_START: | |
3078 | if (!va_list_simple_ptr | |
3079 | || targetm.expand_builtin_va_start != NULL | |
75a70cf9 | 3080 | || built_in_decls[BUILT_IN_NEXT_ARG] == NULL) |
8a58ed0a | 3081 | return NULL_TREE; |
3082 | ||
75a70cf9 | 3083 | if (gimple_call_num_args (call) != 2) |
8a58ed0a | 3084 | return NULL_TREE; |
3085 | ||
75a70cf9 | 3086 | lhs = gimple_call_arg (call, 0); |
8a58ed0a | 3087 | if (!POINTER_TYPE_P (TREE_TYPE (lhs)) |
3088 | || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs))) | |
5f57a8b1 | 3089 | != TYPE_MAIN_VARIANT (cfun_va_list)) |
8a58ed0a | 3090 | return NULL_TREE; |
75a70cf9 | 3091 | |
8a58ed0a | 3092 | lhs = build_fold_indirect_ref (lhs); |
3093 | rhs = build_call_expr (built_in_decls[BUILT_IN_NEXT_ARG], | |
75a70cf9 | 3094 | 1, integer_zero_node); |
8a58ed0a | 3095 | rhs = fold_convert (TREE_TYPE (lhs), rhs); |
3096 | return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs); | |
3097 | ||
3098 | case BUILT_IN_VA_COPY: | |
3099 | if (!va_list_simple_ptr) | |
3100 | return NULL_TREE; | |
3101 | ||
75a70cf9 | 3102 | if (gimple_call_num_args (call) != 2) |
8a58ed0a | 3103 | return NULL_TREE; |
3104 | ||
75a70cf9 | 3105 | lhs = gimple_call_arg (call, 0); |
8a58ed0a | 3106 | if (!POINTER_TYPE_P (TREE_TYPE (lhs)) |
3107 | || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs))) | |
5f57a8b1 | 3108 | != TYPE_MAIN_VARIANT (cfun_va_list)) |
8a58ed0a | 3109 | return NULL_TREE; |
3110 | ||
3111 | lhs = build_fold_indirect_ref (lhs); | |
75a70cf9 | 3112 | rhs = gimple_call_arg (call, 1); |
8a58ed0a | 3113 | if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs)) |
5f57a8b1 | 3114 | != TYPE_MAIN_VARIANT (cfun_va_list)) |
8a58ed0a | 3115 | return NULL_TREE; |
3116 | ||
3117 | rhs = fold_convert (TREE_TYPE (lhs), rhs); | |
3118 | return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs); | |
3119 | ||
3120 | case BUILT_IN_VA_END: | |
75a70cf9 | 3121 | /* No effect, so the statement will be deleted. */ |
8a58ed0a | 3122 | return integer_zero_node; |
3123 | ||
3124 | default: | |
3125 | gcc_unreachable (); | |
3126 | } | |
3127 | } | |
75a70cf9 | 3128 | |
909e5ecb | 3129 | /* Convert EXPR into a GIMPLE value suitable for substitution on the |
3130 | RHS of an assignment. Insert the necessary statements before | |
75a70cf9 | 3131 | iterator *SI_P. The statement at *SI_P, which must be a GIMPLE_CALL |
3132 | is replaced. If the call is expected to produces a result, then it | |
3133 | is replaced by an assignment of the new RHS to the result variable. | |
3134 | If the result is to be ignored, then the call is replaced by a | |
3135 | GIMPLE_NOP. */ | |
909e5ecb | 3136 | |
75a70cf9 | 3137 | static void |
3138 | gimplify_and_update_call_from_tree (gimple_stmt_iterator *si_p, tree expr) | |
909e5ecb | 3139 | { |
75a70cf9 | 3140 | tree lhs; |
3141 | tree tmp = NULL_TREE; /* Silence warning. */ | |
3142 | gimple stmt, new_stmt; | |
3143 | gimple_stmt_iterator i; | |
3144 | gimple_seq stmts = gimple_seq_alloc(); | |
dac18d1a | 3145 | struct gimplify_ctx gctx; |
909e5ecb | 3146 | |
75a70cf9 | 3147 | stmt = gsi_stmt (*si_p); |
3148 | ||
3149 | gcc_assert (is_gimple_call (stmt)); | |
3150 | ||
3151 | lhs = gimple_call_lhs (stmt); | |
3152 | ||
dac18d1a | 3153 | push_gimplify_context (&gctx); |
75a70cf9 | 3154 | |
3155 | if (lhs == NULL_TREE) | |
3156 | gimplify_and_add (expr, &stmts); | |
3157 | else | |
a280136a | 3158 | tmp = get_initialized_tmp_var (expr, &stmts, NULL); |
75a70cf9 | 3159 | |
909e5ecb | 3160 | pop_gimplify_context (NULL); |
3161 | ||
75a70cf9 | 3162 | if (gimple_has_location (stmt)) |
3163 | annotate_all_with_location (stmts, gimple_location (stmt)); | |
b66731e8 | 3164 | |
909e5ecb | 3165 | /* The replacement can expose previously unreferenced variables. */ |
75a70cf9 | 3166 | for (i = gsi_start (stmts); !gsi_end_p (i); gsi_next (&i)) |
3167 | { | |
3168 | new_stmt = gsi_stmt (i); | |
3169 | find_new_referenced_vars (new_stmt); | |
3170 | gsi_insert_before (si_p, new_stmt, GSI_NEW_STMT); | |
3171 | mark_symbols_for_renaming (new_stmt); | |
3172 | gsi_next (si_p); | |
3173 | } | |
3174 | ||
3175 | if (lhs == NULL_TREE) | |
dd277d48 | 3176 | { |
3177 | new_stmt = gimple_build_nop (); | |
3178 | unlink_stmt_vdef (stmt); | |
3179 | release_defs (stmt); | |
3180 | } | |
75a70cf9 | 3181 | else |
909e5ecb | 3182 | { |
75a70cf9 | 3183 | new_stmt = gimple_build_assign (lhs, tmp); |
dd277d48 | 3184 | gimple_set_vuse (new_stmt, gimple_vuse (stmt)); |
3185 | gimple_set_vdef (new_stmt, gimple_vdef (stmt)); | |
75a70cf9 | 3186 | move_ssa_defining_stmt_for_defs (new_stmt, stmt); |
909e5ecb | 3187 | } |
3188 | ||
75a70cf9 | 3189 | gimple_set_location (new_stmt, gimple_location (stmt)); |
3190 | gsi_replace (si_p, new_stmt, false); | |
909e5ecb | 3191 | } |
3192 | ||
4ee9c684 | 3193 | /* A simple pass that attempts to fold all builtin functions. This pass |
3194 | is run after we've propagated as many constants as we can. */ | |
3195 | ||
2a1990e9 | 3196 | static unsigned int |
4ee9c684 | 3197 | execute_fold_all_builtins (void) |
3198 | { | |
b36237eb | 3199 | bool cfg_changed = false; |
4ee9c684 | 3200 | basic_block bb; |
b1b7c0c4 | 3201 | unsigned int todoflags = 0; |
3202 | ||
4ee9c684 | 3203 | FOR_EACH_BB (bb) |
3204 | { | |
75a70cf9 | 3205 | gimple_stmt_iterator i; |
3206 | for (i = gsi_start_bb (bb); !gsi_end_p (i); ) | |
4ee9c684 | 3207 | { |
75a70cf9 | 3208 | gimple stmt, old_stmt; |
4ee9c684 | 3209 | tree callee, result; |
0a39fd54 | 3210 | enum built_in_function fcode; |
4ee9c684 | 3211 | |
75a70cf9 | 3212 | stmt = gsi_stmt (i); |
3213 | ||
3214 | if (gimple_code (stmt) != GIMPLE_CALL) | |
0a39fd54 | 3215 | { |
75a70cf9 | 3216 | gsi_next (&i); |
0a39fd54 | 3217 | continue; |
3218 | } | |
75a70cf9 | 3219 | callee = gimple_call_fndecl (stmt); |
4ee9c684 | 3220 | if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL) |
0a39fd54 | 3221 | { |
75a70cf9 | 3222 | gsi_next (&i); |
0a39fd54 | 3223 | continue; |
3224 | } | |
3225 | fcode = DECL_FUNCTION_CODE (callee); | |
4ee9c684 | 3226 | |
75a70cf9 | 3227 | result = ccp_fold_builtin (stmt); |
5a4b7e1e | 3228 | |
3229 | if (result) | |
75a70cf9 | 3230 | gimple_remove_stmt_histograms (cfun, stmt); |
5a4b7e1e | 3231 | |
4ee9c684 | 3232 | if (!result) |
3233 | switch (DECL_FUNCTION_CODE (callee)) | |
3234 | { | |
3235 | case BUILT_IN_CONSTANT_P: | |
3236 | /* Resolve __builtin_constant_p. If it hasn't been | |
3237 | folded to integer_one_node by now, it's fairly | |
3238 | certain that the value simply isn't constant. */ | |
75a70cf9 | 3239 | result = integer_zero_node; |
4ee9c684 | 3240 | break; |
3241 | ||
bdd0e199 | 3242 | case BUILT_IN_STACK_RESTORE: |
75a70cf9 | 3243 | result = optimize_stack_restore (i); |
8a58ed0a | 3244 | if (result) |
3245 | break; | |
75a70cf9 | 3246 | gsi_next (&i); |
8a58ed0a | 3247 | continue; |
3248 | ||
3249 | case BUILT_IN_VA_START: | |
3250 | case BUILT_IN_VA_END: | |
3251 | case BUILT_IN_VA_COPY: | |
3252 | /* These shouldn't be folded before pass_stdarg. */ | |
75a70cf9 | 3253 | result = optimize_stdarg_builtin (stmt); |
bdd0e199 | 3254 | if (result) |
3255 | break; | |
3256 | /* FALLTHRU */ | |
3257 | ||
4ee9c684 | 3258 | default: |
75a70cf9 | 3259 | gsi_next (&i); |
4ee9c684 | 3260 | continue; |
3261 | } | |
3262 | ||
3263 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3264 | { | |
3265 | fprintf (dump_file, "Simplified\n "); | |
75a70cf9 | 3266 | print_gimple_stmt (dump_file, stmt, 0, dump_flags); |
4ee9c684 | 3267 | } |
3268 | ||
75a70cf9 | 3269 | old_stmt = stmt; |
3270 | push_stmt_changes (gsi_stmt_ptr (&i)); | |
de6ed584 | 3271 | |
75a70cf9 | 3272 | if (!update_call_from_tree (&i, result)) |
dd277d48 | 3273 | gimplify_and_update_call_from_tree (&i, result); |
de6ed584 | 3274 | |
75a70cf9 | 3275 | stmt = gsi_stmt (i); |
3276 | pop_stmt_changes (gsi_stmt_ptr (&i)); | |
de6ed584 | 3277 | |
75a70cf9 | 3278 | if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt) |
3279 | && gimple_purge_dead_eh_edges (bb)) | |
b36237eb | 3280 | cfg_changed = true; |
4ee9c684 | 3281 | |
3282 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
3283 | { | |
3284 | fprintf (dump_file, "to\n "); | |
75a70cf9 | 3285 | print_gimple_stmt (dump_file, stmt, 0, dump_flags); |
4ee9c684 | 3286 | fprintf (dump_file, "\n"); |
3287 | } | |
0a39fd54 | 3288 | |
3289 | /* Retry the same statement if it changed into another | |
3290 | builtin, there might be new opportunities now. */ | |
75a70cf9 | 3291 | if (gimple_code (stmt) != GIMPLE_CALL) |
0a39fd54 | 3292 | { |
75a70cf9 | 3293 | gsi_next (&i); |
0a39fd54 | 3294 | continue; |
3295 | } | |
75a70cf9 | 3296 | callee = gimple_call_fndecl (stmt); |
0a39fd54 | 3297 | if (!callee |
75a70cf9 | 3298 | || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL |
0a39fd54 | 3299 | || DECL_FUNCTION_CODE (callee) == fcode) |
75a70cf9 | 3300 | gsi_next (&i); |
4ee9c684 | 3301 | } |
3302 | } | |
b1b7c0c4 | 3303 | |
b36237eb | 3304 | /* Delete unreachable blocks. */ |
b1b7c0c4 | 3305 | if (cfg_changed) |
3306 | todoflags |= TODO_cleanup_cfg; | |
3307 | ||
3308 | return todoflags; | |
4ee9c684 | 3309 | } |
3310 | ||
41511585 | 3311 | |
20099e35 | 3312 | struct gimple_opt_pass pass_fold_builtins = |
4ee9c684 | 3313 | { |
20099e35 | 3314 | { |
3315 | GIMPLE_PASS, | |
4ee9c684 | 3316 | "fab", /* name */ |
3317 | NULL, /* gate */ | |
3318 | execute_fold_all_builtins, /* execute */ | |
3319 | NULL, /* sub */ | |
3320 | NULL, /* next */ | |
3321 | 0, /* static_pass_number */ | |
3322 | 0, /* tv_id */ | |
49290934 | 3323 | PROP_cfg | PROP_ssa, /* properties_required */ |
4ee9c684 | 3324 | 0, /* properties_provided */ |
3325 | 0, /* properties_destroyed */ | |
3326 | 0, /* todo_flags_start */ | |
909e5ecb | 3327 | TODO_dump_func |
3328 | | TODO_verify_ssa | |
20099e35 | 3329 | | TODO_update_ssa /* todo_flags_finish */ |
3330 | } | |
4ee9c684 | 3331 | }; |