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6de9cd9a | 1 | /* Conditional constant propagation pass for the GNU compiler. |
06a9b53f | 2 | Copyright (C) 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc. |
6de9cd9a DN |
3 | Adapted from original RTL SSA-CCP by Daniel Berlin <dberlin@dberlin.org> |
4 | Adapted to GIMPLE trees by Diego Novillo <dnovillo@redhat.com> | |
5 | ||
6 | This file is part of GCC. | |
7 | ||
8 | GCC is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU General Public License as published by the | |
10 | Free Software Foundation; either version 2, or (at your option) any | |
11 | later version. | |
12 | ||
13 | GCC is distributed in the hope that it will be useful, but WITHOUT | |
14 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
15 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
16 | for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with GCC; see the file COPYING. If not, write to the Free | |
20 | Software Foundation, 59 Temple Place - Suite 330, Boston, MA | |
21 | 02111-1307, USA. */ | |
22 | ||
23 | /* Conditional constant propagation. | |
24 | ||
25 | References: | |
26 | ||
27 | Constant propagation with conditional branches, | |
28 | Wegman and Zadeck, ACM TOPLAS 13(2):181-210. | |
29 | ||
30 | Building an Optimizing Compiler, | |
31 | Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9. | |
32 | ||
33 | Advanced Compiler Design and Implementation, | |
34 | Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6 */ | |
35 | ||
36 | #include "config.h" | |
37 | #include "system.h" | |
38 | #include "coretypes.h" | |
39 | #include "tm.h" | |
6de9cd9a | 40 | #include "tree.h" |
750628d8 | 41 | #include "flags.h" |
6de9cd9a DN |
42 | #include "rtl.h" |
43 | #include "tm_p.h" | |
750628d8 | 44 | #include "ggc.h" |
6de9cd9a | 45 | #include "basic-block.h" |
750628d8 DN |
46 | #include "output.h" |
47 | #include "errors.h" | |
48 | #include "expr.h" | |
49 | #include "function.h" | |
6de9cd9a | 50 | #include "diagnostic.h" |
750628d8 | 51 | #include "timevar.h" |
6de9cd9a | 52 | #include "tree-dump.h" |
750628d8 | 53 | #include "tree-flow.h" |
6de9cd9a | 54 | #include "tree-pass.h" |
750628d8 DN |
55 | #include "tree-ssa-propagate.h" |
56 | #include "langhooks.h" | |
6de9cd9a DN |
57 | |
58 | ||
59 | /* Possible lattice values. */ | |
60 | typedef enum | |
61 | { | |
62 | UNINITIALIZED = 0, | |
63 | UNDEFINED, | |
173b818d | 64 | UNKNOWN_VAL, |
6de9cd9a DN |
65 | CONSTANT, |
66 | VARYING | |
67 | } latticevalue; | |
68 | ||
6de9cd9a DN |
69 | /* Main structure for CCP. Contains the lattice value and, if it's a |
70 | constant, the constant value. */ | |
71 | typedef struct | |
72 | { | |
73 | latticevalue lattice_val; | |
74 | tree const_val; | |
75 | } value; | |
76 | ||
6de9cd9a DN |
77 | /* This is used to track the current value of each variable. */ |
78 | static value *value_vector; | |
79 | ||
750628d8 DN |
80 | |
81 | /* Dump lattice value VAL to file OUTF prefixed by PREFIX. */ | |
95eec0d6 DB |
82 | |
83 | static void | |
750628d8 | 84 | dump_lattice_value (FILE *outf, const char *prefix, value val) |
95eec0d6 | 85 | { |
750628d8 | 86 | switch (val.lattice_val) |
95eec0d6 | 87 | { |
750628d8 DN |
88 | case UNDEFINED: |
89 | fprintf (outf, "%sUNDEFINED", prefix); | |
90 | break; | |
91 | case VARYING: | |
92 | fprintf (outf, "%sVARYING", prefix); | |
93 | break; | |
94 | case UNKNOWN_VAL: | |
95 | fprintf (outf, "%sUNKNOWN_VAL", prefix); | |
96 | break; | |
97 | case CONSTANT: | |
98 | fprintf (outf, "%sCONSTANT ", prefix); | |
99 | print_generic_expr (outf, val.const_val, dump_flags); | |
100 | break; | |
101 | default: | |
1e128c5f | 102 | gcc_unreachable (); |
750628d8 | 103 | } |
95eec0d6 | 104 | } |
6de9cd9a | 105 | |
6de9cd9a | 106 | |
750628d8 | 107 | /* Return a default value for variable VAR using the following rules: |
6de9cd9a | 108 | |
750628d8 DN |
109 | 1- Function arguments are considered VARYING. |
110 | ||
111 | 2- Global and static variables that are declared constant are | |
112 | considered CONSTANT. | |
6de9cd9a | 113 | |
750628d8 | 114 | 3- Any other virtually defined variable is considered UNKNOWN_VAL. |
95eec0d6 | 115 | |
750628d8 DN |
116 | 4- Any other value is considered UNDEFINED. This is useful when |
117 | considering PHI nodes. PHI arguments that are undefined do not | |
118 | change the constant value of the PHI node, which allows for more | |
119 | constants to be propagated. */ | |
6de9cd9a | 120 | |
750628d8 DN |
121 | static value |
122 | get_default_value (tree var) | |
123 | { | |
124 | value val; | |
125 | tree sym; | |
6de9cd9a | 126 | |
750628d8 DN |
127 | if (TREE_CODE (var) == SSA_NAME) |
128 | sym = SSA_NAME_VAR (var); | |
129 | else | |
130 | { | |
1e128c5f | 131 | gcc_assert (DECL_P (var)); |
750628d8 DN |
132 | sym = var; |
133 | } | |
6de9cd9a | 134 | |
750628d8 DN |
135 | val.lattice_val = UNDEFINED; |
136 | val.const_val = NULL_TREE; | |
6de9cd9a | 137 | |
195da47b | 138 | if (TREE_CODE (var) == SSA_NAME |
3aecd08b JL |
139 | && SSA_NAME_VALUE (var) |
140 | && is_gimple_min_invariant (SSA_NAME_VALUE (var))) | |
195da47b JL |
141 | { |
142 | val.lattice_val = CONSTANT; | |
3aecd08b | 143 | val.const_val = SSA_NAME_VALUE (var); |
195da47b JL |
144 | } |
145 | else if (TREE_CODE (sym) == PARM_DECL || TREE_THIS_VOLATILE (sym)) | |
6de9cd9a | 146 | { |
750628d8 DN |
147 | /* Function arguments and volatile variables are considered VARYING. */ |
148 | val.lattice_val = VARYING; | |
6de9cd9a | 149 | } |
750628d8 DN |
150 | else if (TREE_STATIC (sym)) |
151 | { | |
152 | /* Globals and static variables are considered UNKNOWN_VAL, | |
153 | unless they are declared 'const'. */ | |
154 | if (TREE_READONLY (sym) | |
155 | && DECL_INITIAL (sym) | |
156 | && is_gimple_min_invariant (DECL_INITIAL (sym))) | |
157 | { | |
158 | val.lattice_val = CONSTANT; | |
159 | val.const_val = DECL_INITIAL (sym); | |
160 | } | |
161 | else | |
162 | { | |
163 | val.const_val = NULL_TREE; | |
164 | val.lattice_val = UNKNOWN_VAL; | |
165 | } | |
166 | } | |
167 | else if (!is_gimple_reg (sym)) | |
168 | { | |
169 | val.const_val = NULL_TREE; | |
170 | val.lattice_val = UNKNOWN_VAL; | |
171 | } | |
172 | else | |
173 | { | |
174 | enum tree_code code; | |
175 | tree stmt = SSA_NAME_DEF_STMT (var); | |
6de9cd9a | 176 | |
750628d8 DN |
177 | if (!IS_EMPTY_STMT (stmt)) |
178 | { | |
179 | code = TREE_CODE (stmt); | |
180 | if (code != MODIFY_EXPR && code != PHI_NODE) | |
181 | val.lattice_val = VARYING; | |
182 | } | |
183 | } | |
6de9cd9a | 184 | |
750628d8 DN |
185 | return val; |
186 | } | |
6de9cd9a | 187 | |
6de9cd9a DN |
188 | /* Get the constant value associated with variable VAR. */ |
189 | ||
190 | static value * | |
191 | get_value (tree var) | |
192 | { | |
193 | value *val; | |
194 | ||
1e128c5f | 195 | gcc_assert (TREE_CODE (var) == SSA_NAME); |
6de9cd9a DN |
196 | |
197 | val = &value_vector[SSA_NAME_VERSION (var)]; | |
198 | if (val->lattice_val == UNINITIALIZED) | |
199 | *val = get_default_value (var); | |
200 | ||
201 | return val; | |
202 | } | |
203 | ||
204 | ||
750628d8 DN |
205 | /* Set the lattice value for variable VAR to VAL. Return true if VAL |
206 | is different from VAR's previous value. */ | |
6de9cd9a | 207 | |
750628d8 DN |
208 | static bool |
209 | set_lattice_value (tree var, value val) | |
6de9cd9a | 210 | { |
750628d8 | 211 | value *old = get_value (var); |
6de9cd9a | 212 | |
750628d8 | 213 | if (val.lattice_val == UNDEFINED) |
6de9cd9a | 214 | { |
750628d8 | 215 | /* CONSTANT->UNDEFINED is never a valid state transition. */ |
1e128c5f | 216 | gcc_assert (old->lattice_val != CONSTANT); |
750628d8 DN |
217 | |
218 | /* UNKNOWN_VAL->UNDEFINED is never a valid state transition. */ | |
1e128c5f | 219 | gcc_assert (old->lattice_val != UNKNOWN_VAL); |
6de9cd9a | 220 | |
750628d8 DN |
221 | /* VARYING->UNDEFINED is generally not a valid state transition, |
222 | except for values which are initialized to VARYING. */ | |
1e128c5f GB |
223 | gcc_assert (old->lattice_val != VARYING |
224 | || get_default_value (var).lattice_val == VARYING); | |
6de9cd9a | 225 | } |
750628d8 | 226 | else if (val.lattice_val == CONSTANT) |
1e128c5f GB |
227 | /* VARYING -> CONSTANT is an invalid state transition, except |
228 | for objects which start off in a VARYING state. */ | |
e1537934 NS |
229 | gcc_assert (old->lattice_val != VARYING |
230 | || get_default_value (var).lattice_val == VARYING); | |
6de9cd9a | 231 | |
750628d8 DN |
232 | /* If the constant for VAR has changed, then this VAR is really varying. */ |
233 | if (old->lattice_val == CONSTANT | |
234 | && val.lattice_val == CONSTANT | |
235 | && !simple_cst_equal (old->const_val, val.const_val)) | |
6de9cd9a | 236 | { |
750628d8 DN |
237 | val.lattice_val = VARYING; |
238 | val.const_val = NULL_TREE; | |
6de9cd9a | 239 | } |
750628d8 DN |
240 | |
241 | if (old->lattice_val != val.lattice_val) | |
6de9cd9a | 242 | { |
750628d8 DN |
243 | if (dump_file && (dump_flags & TDF_DETAILS)) |
244 | { | |
245 | dump_lattice_value (dump_file, "Lattice value changed to ", val); | |
246 | fprintf (dump_file, ". Adding definition to SSA edges.\n"); | |
247 | } | |
248 | ||
249 | *old = val; | |
250 | return true; | |
6de9cd9a | 251 | } |
750628d8 DN |
252 | |
253 | return false; | |
6de9cd9a DN |
254 | } |
255 | ||
256 | ||
750628d8 | 257 | /* Set the lattice value for the variable VAR to VARYING. */ |
6de9cd9a DN |
258 | |
259 | static void | |
750628d8 | 260 | def_to_varying (tree var) |
6de9cd9a | 261 | { |
750628d8 DN |
262 | value val; |
263 | val.lattice_val = VARYING; | |
264 | val.const_val = NULL_TREE; | |
265 | set_lattice_value (var, val); | |
266 | } | |
6de9cd9a | 267 | |
6de9cd9a | 268 | |
750628d8 | 269 | /* Return the likely latticevalue for STMT. |
6de9cd9a | 270 | |
750628d8 | 271 | If STMT has no operands, then return CONSTANT. |
6de9cd9a | 272 | |
750628d8 | 273 | Else if any operands of STMT are undefined, then return UNDEFINED. |
6de9cd9a | 274 | |
750628d8 | 275 | Else if any operands of STMT are constants, then return CONSTANT. |
6de9cd9a | 276 | |
750628d8 | 277 | Else return VARYING. */ |
6de9cd9a | 278 | |
750628d8 DN |
279 | static latticevalue |
280 | likely_value (tree stmt) | |
281 | { | |
282 | vuse_optype vuses; | |
283 | int found_constant = 0; | |
284 | stmt_ann_t ann; | |
285 | tree use; | |
286 | ssa_op_iter iter; | |
6de9cd9a | 287 | |
750628d8 DN |
288 | /* If the statement makes aliased loads or has volatile operands, it |
289 | won't fold to a constant value. */ | |
290 | ann = stmt_ann (stmt); | |
291 | if (ann->makes_aliased_loads || ann->has_volatile_ops) | |
292 | return VARYING; | |
6de9cd9a | 293 | |
750628d8 DN |
294 | /* A CALL_EXPR is assumed to be varying. This may be overly conservative, |
295 | in the presence of const and pure calls. */ | |
296 | if (get_call_expr_in (stmt) != NULL_TREE) | |
297 | return VARYING; | |
6de9cd9a | 298 | |
750628d8 | 299 | get_stmt_operands (stmt); |
6de9cd9a | 300 | |
750628d8 DN |
301 | FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE) |
302 | { | |
303 | value *val = get_value (use); | |
304 | ||
305 | if (val->lattice_val == UNDEFINED) | |
306 | return UNDEFINED; | |
307 | ||
308 | if (val->lattice_val == CONSTANT) | |
309 | found_constant = 1; | |
310 | } | |
311 | ||
312 | vuses = VUSE_OPS (ann); | |
313 | ||
314 | if (NUM_VUSES (vuses)) | |
315 | { | |
316 | tree vuse = VUSE_OP (vuses, 0); | |
317 | value *val = get_value (vuse); | |
318 | ||
319 | if (val->lattice_val == UNKNOWN_VAL) | |
320 | return UNKNOWN_VAL; | |
321 | ||
1e128c5f GB |
322 | /* There should be no VUSE operands that are UNDEFINED. */ |
323 | gcc_assert (val->lattice_val != UNDEFINED); | |
750628d8 DN |
324 | |
325 | if (val->lattice_val == CONSTANT) | |
326 | found_constant = 1; | |
6de9cd9a | 327 | } |
750628d8 DN |
328 | |
329 | return ((found_constant || (!USE_OPS (ann) && !vuses)) ? CONSTANT : VARYING); | |
6de9cd9a DN |
330 | } |
331 | ||
332 | ||
750628d8 DN |
333 | /* Function indicating whether we ought to include information for VAR |
334 | when calculating immediate uses. */ | |
335 | ||
336 | static bool | |
337 | need_imm_uses_for (tree var) | |
338 | { | |
339 | return get_value (var)->lattice_val != VARYING; | |
340 | } | |
341 | ||
342 | ||
343 | /* Initialize local data structures for CCP. */ | |
6de9cd9a DN |
344 | |
345 | static void | |
750628d8 | 346 | ccp_initialize (void) |
6de9cd9a | 347 | { |
750628d8 DN |
348 | basic_block bb; |
349 | sbitmap is_may_def; | |
6de9cd9a | 350 | |
750628d8 DN |
351 | value_vector = (value *) xmalloc (num_ssa_names * sizeof (value)); |
352 | memset (value_vector, 0, num_ssa_names * sizeof (value)); | |
6de9cd9a | 353 | |
750628d8 DN |
354 | /* Set of SSA_NAMEs that are defined by a V_MAY_DEF. */ |
355 | is_may_def = sbitmap_alloc (num_ssa_names); | |
356 | sbitmap_zero (is_may_def); | |
6de9cd9a | 357 | |
750628d8 DN |
358 | /* Initialize simulation flags for PHI nodes and statements. */ |
359 | FOR_EACH_BB (bb) | |
6de9cd9a | 360 | { |
750628d8 | 361 | block_stmt_iterator i; |
6de9cd9a | 362 | |
750628d8 DN |
363 | /* Mark all V_MAY_DEF operands VARYING. */ |
364 | for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) | |
365 | { | |
366 | bool is_varying = false; | |
367 | tree stmt = bsi_stmt (i); | |
368 | ssa_op_iter iter; | |
369 | tree def; | |
6de9cd9a | 370 | |
750628d8 | 371 | get_stmt_operands (stmt); |
173b818d | 372 | |
750628d8 DN |
373 | /* Get the default value for each DEF and V_MUST_DEF. */ |
374 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, | |
375 | (SSA_OP_DEF | SSA_OP_VMUSTDEF)) | |
376 | { | |
377 | if (get_value (def)->lattice_val == VARYING) | |
378 | is_varying = true; | |
379 | } | |
6de9cd9a | 380 | |
750628d8 DN |
381 | /* Mark all V_MAY_DEF operands VARYING. */ |
382 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_VMAYDEF) | |
383 | { | |
384 | get_value (def)->lattice_val = VARYING; | |
385 | SET_BIT (is_may_def, SSA_NAME_VERSION (def)); | |
386 | } | |
387 | ||
388 | /* Statements other than MODIFY_EXPR, COND_EXPR and | |
389 | SWITCH_EXPR are not interesting for constant propagation. | |
390 | Mark them VARYING. */ | |
391 | if (TREE_CODE (stmt) != MODIFY_EXPR | |
392 | && TREE_CODE (stmt) != COND_EXPR | |
393 | && TREE_CODE (stmt) != SWITCH_EXPR) | |
394 | is_varying = true; | |
395 | ||
396 | DONT_SIMULATE_AGAIN (stmt) = is_varying; | |
397 | } | |
6de9cd9a DN |
398 | } |
399 | ||
750628d8 DN |
400 | /* Now process PHI nodes. */ |
401 | FOR_EACH_BB (bb) | |
6de9cd9a | 402 | { |
750628d8 DN |
403 | tree phi, var; |
404 | int x; | |
405 | ||
406 | for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) | |
407 | { | |
408 | value *val = get_value (PHI_RESULT (phi)); | |
409 | ||
410 | for (x = 0; x < PHI_NUM_ARGS (phi); x++) | |
411 | { | |
412 | var = PHI_ARG_DEF (phi, x); | |
413 | ||
414 | /* If one argument has a V_MAY_DEF, the result is | |
415 | VARYING. */ | |
416 | if (TREE_CODE (var) == SSA_NAME) | |
417 | { | |
418 | if (TEST_BIT (is_may_def, SSA_NAME_VERSION (var))) | |
419 | { | |
420 | val->lattice_val = VARYING; | |
421 | SET_BIT (is_may_def, SSA_NAME_VERSION (PHI_RESULT (phi))); | |
422 | break; | |
423 | } | |
424 | } | |
425 | } | |
426 | ||
427 | DONT_SIMULATE_AGAIN (phi) = (val->lattice_val == VARYING); | |
428 | } | |
6de9cd9a | 429 | } |
6de9cd9a | 430 | |
750628d8 | 431 | sbitmap_free (is_may_def); |
6de9cd9a | 432 | |
750628d8 DN |
433 | /* Compute immediate uses for variables we care about. */ |
434 | compute_immediate_uses (TDFA_USE_OPS | TDFA_USE_VOPS, need_imm_uses_for); | |
435 | } | |
6de9cd9a | 436 | |
6de9cd9a | 437 | |
750628d8 DN |
438 | /* Replace USE references in statement STMT with their immediate reaching |
439 | definition. Return true if at least one reference was replaced. If | |
440 | REPLACED_ADDRESSES_P is given, it will be set to true if an address | |
441 | constant was replaced. */ | |
6de9cd9a | 442 | |
750628d8 DN |
443 | static bool |
444 | replace_uses_in (tree stmt, bool *replaced_addresses_p) | |
445 | { | |
446 | bool replaced = false; | |
447 | use_operand_p use; | |
448 | ssa_op_iter iter; | |
6de9cd9a | 449 | |
750628d8 DN |
450 | if (replaced_addresses_p) |
451 | *replaced_addresses_p = false; | |
6de9cd9a | 452 | |
750628d8 | 453 | get_stmt_operands (stmt); |
6de9cd9a | 454 | |
750628d8 | 455 | FOR_EACH_SSA_USE_OPERAND (use, stmt, iter, SSA_OP_USE) |
173b818d | 456 | { |
aa24864c RH |
457 | tree tuse = USE_FROM_PTR (use); |
458 | value *val = get_value (tuse); | |
750628d8 | 459 | |
aa24864c RH |
460 | if (val->lattice_val != CONSTANT) |
461 | continue; | |
462 | ||
463 | if (TREE_CODE (stmt) == ASM_EXPR | |
464 | && !may_propagate_copy_into_asm (tuse)) | |
465 | continue; | |
466 | ||
467 | SET_USE (use, val->const_val); | |
468 | ||
469 | replaced = true; | |
470 | if (POINTER_TYPE_P (TREE_TYPE (tuse)) && replaced_addresses_p) | |
471 | *replaced_addresses_p = true; | |
173b818d | 472 | } |
750628d8 DN |
473 | |
474 | return replaced; | |
6de9cd9a DN |
475 | } |
476 | ||
477 | ||
750628d8 DN |
478 | /* Replace the VUSE references in statement STMT with its immediate reaching |
479 | definition. Return true if the reference was replaced. If | |
480 | REPLACED_ADDRESSES_P is given, it will be set to true if an address | |
481 | constant was replaced. */ | |
6de9cd9a | 482 | |
750628d8 DN |
483 | static bool |
484 | replace_vuse_in (tree stmt, bool *replaced_addresses_p) | |
6de9cd9a | 485 | { |
750628d8 DN |
486 | bool replaced = false; |
487 | vuse_optype vuses; | |
488 | use_operand_p vuse; | |
489 | value *val; | |
6de9cd9a | 490 | |
750628d8 DN |
491 | if (replaced_addresses_p) |
492 | *replaced_addresses_p = false; | |
6de9cd9a | 493 | |
750628d8 | 494 | get_stmt_operands (stmt); |
6de9cd9a | 495 | |
750628d8 | 496 | vuses = STMT_VUSE_OPS (stmt); |
173b818d | 497 | |
750628d8 DN |
498 | if (NUM_VUSES (vuses) != 1) |
499 | return false; | |
500 | ||
501 | vuse = VUSE_OP_PTR (vuses, 0); | |
502 | val = get_value (USE_FROM_PTR (vuse)); | |
503 | ||
504 | if (val->lattice_val == CONSTANT | |
505 | && TREE_CODE (stmt) == MODIFY_EXPR | |
506 | && DECL_P (TREE_OPERAND (stmt, 1)) | |
507 | && TREE_OPERAND (stmt, 1) == SSA_NAME_VAR (USE_FROM_PTR (vuse))) | |
6de9cd9a | 508 | { |
750628d8 DN |
509 | TREE_OPERAND (stmt, 1) = val->const_val; |
510 | replaced = true; | |
511 | if (POINTER_TYPE_P (TREE_TYPE (USE_FROM_PTR (vuse))) | |
512 | && replaced_addresses_p) | |
513 | *replaced_addresses_p = true; | |
6de9cd9a DN |
514 | } |
515 | ||
750628d8 | 516 | return replaced; |
6de9cd9a DN |
517 | } |
518 | ||
519 | ||
750628d8 DN |
520 | /* Perform final substitution and folding. After this pass the program |
521 | should still be in SSA form. */ | |
6de9cd9a DN |
522 | |
523 | static void | |
750628d8 | 524 | substitute_and_fold (void) |
6de9cd9a | 525 | { |
750628d8 | 526 | basic_block bb; |
195da47b | 527 | unsigned int i; |
6de9cd9a DN |
528 | |
529 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
750628d8 DN |
530 | fprintf (dump_file, |
531 | "\nSubstituing constants and folding statements\n\n"); | |
532 | ||
533 | /* Substitute constants in every statement of every basic block. */ | |
534 | FOR_EACH_BB (bb) | |
6de9cd9a | 535 | { |
750628d8 DN |
536 | block_stmt_iterator i; |
537 | tree phi; | |
6de9cd9a | 538 | |
750628d8 DN |
539 | /* Propagate our known constants into PHI nodes. */ |
540 | for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) | |
541 | { | |
542 | int i; | |
6de9cd9a | 543 | |
750628d8 DN |
544 | for (i = 0; i < PHI_NUM_ARGS (phi); i++) |
545 | { | |
546 | value *new_val; | |
547 | use_operand_p orig_p = PHI_ARG_DEF_PTR (phi, i); | |
548 | tree orig = USE_FROM_PTR (orig_p); | |
6de9cd9a | 549 | |
750628d8 DN |
550 | if (! SSA_VAR_P (orig)) |
551 | break; | |
6de9cd9a | 552 | |
750628d8 DN |
553 | new_val = get_value (orig); |
554 | if (new_val->lattice_val == CONSTANT | |
555 | && may_propagate_copy (orig, new_val->const_val)) | |
556 | SET_USE (orig_p, new_val->const_val); | |
557 | } | |
6de9cd9a | 558 | } |
6de9cd9a | 559 | |
750628d8 DN |
560 | for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) |
561 | { | |
562 | bool replaced_address; | |
563 | tree stmt = bsi_stmt (i); | |
6de9cd9a | 564 | |
750628d8 DN |
565 | /* Skip statements that have been folded already. */ |
566 | if (stmt_modified_p (stmt) || !is_exec_stmt (stmt)) | |
567 | continue; | |
6de9cd9a | 568 | |
750628d8 DN |
569 | /* Replace the statement with its folded version and mark it |
570 | folded. */ | |
571 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
572 | { | |
573 | fprintf (dump_file, "Line %d: replaced ", get_lineno (stmt)); | |
574 | print_generic_stmt (dump_file, stmt, TDF_SLIM); | |
575 | } | |
6de9cd9a | 576 | |
750628d8 DN |
577 | if (replace_uses_in (stmt, &replaced_address) |
578 | || replace_vuse_in (stmt, &replaced_address)) | |
579 | { | |
580 | bool changed = fold_stmt (bsi_stmt_ptr (i)); | |
581 | stmt = bsi_stmt(i); | |
582 | /* If we folded a builtin function, we'll likely | |
583 | need to rename VDEFs. */ | |
584 | if (replaced_address || changed) | |
585 | { | |
586 | mark_new_vars_to_rename (stmt, vars_to_rename); | |
587 | if (maybe_clean_eh_stmt (stmt)) | |
588 | tree_purge_dead_eh_edges (bb); | |
589 | } | |
590 | else | |
591 | modify_stmt (stmt); | |
592 | } | |
593 | ||
594 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
595 | { | |
596 | fprintf (dump_file, " with "); | |
597 | print_generic_stmt (dump_file, stmt, TDF_SLIM); | |
598 | fprintf (dump_file, "\n"); | |
599 | } | |
600 | } | |
601 | } | |
195da47b JL |
602 | |
603 | /* And transfer what we learned from VALUE_VECTOR into the | |
604 | SSA_NAMEs themselves. This probably isn't terribly important | |
605 | since we probably constant propagated the values to their | |
606 | use sites above. */ | |
607 | for (i = 0; i < num_ssa_names; i++) | |
608 | { | |
609 | tree name = ssa_name (i); | |
610 | value *value; | |
611 | ||
612 | if (!name) | |
613 | continue; | |
614 | ||
615 | value = get_value (name); | |
616 | if (value->lattice_val == CONSTANT | |
617 | && is_gimple_reg (name) | |
618 | && is_gimple_min_invariant (value->const_val)) | |
3aecd08b | 619 | SSA_NAME_VALUE (name) = value->const_val; |
195da47b | 620 | } |
6de9cd9a DN |
621 | } |
622 | ||
623 | ||
750628d8 | 624 | /* Free allocated storage. */ |
6de9cd9a DN |
625 | |
626 | static void | |
750628d8 | 627 | ccp_finalize (void) |
6de9cd9a | 628 | { |
750628d8 DN |
629 | /* Perform substitutions based on the known constant values. */ |
630 | substitute_and_fold (); | |
6de9cd9a | 631 | |
750628d8 DN |
632 | /* Now cleanup any unreachable code. */ |
633 | cleanup_tree_cfg (); | |
173b818d | 634 | |
750628d8 DN |
635 | free (value_vector); |
636 | } | |
6de9cd9a | 637 | |
173b818d | 638 | |
750628d8 DN |
639 | |
640 | /* Compute the meet operator between VAL1 and VAL2: | |
641 | ||
642 | any M UNDEFINED = any | |
643 | any M VARYING = VARYING | |
644 | any M UNKNOWN_VAL = UNKNOWN_VAL | |
645 | Ci M Cj = Ci if (i == j) | |
646 | Ci M Cj = VARYING if (i != j) */ | |
647 | static value | |
648 | ccp_lattice_meet (value val1, value val2) | |
649 | { | |
650 | value result; | |
651 | ||
652 | /* any M UNDEFINED = any. */ | |
653 | if (val1.lattice_val == UNDEFINED) | |
654 | return val2; | |
655 | else if (val2.lattice_val == UNDEFINED) | |
656 | return val1; | |
657 | ||
658 | /* any M VARYING = VARYING. */ | |
659 | if (val1.lattice_val == VARYING || val2.lattice_val == VARYING) | |
6de9cd9a | 660 | { |
750628d8 DN |
661 | result.lattice_val = VARYING; |
662 | result.const_val = NULL_TREE; | |
663 | return result; | |
6de9cd9a DN |
664 | } |
665 | ||
750628d8 DN |
666 | /* any M UNKNOWN_VAL = UNKNOWN_VAL. */ |
667 | if (val1.lattice_val == UNKNOWN_VAL | |
668 | || val2.lattice_val == UNKNOWN_VAL) | |
669 | { | |
670 | result.lattice_val = UNKNOWN_VAL; | |
671 | result.const_val = NULL_TREE; | |
672 | return result; | |
673 | } | |
6de9cd9a | 674 | |
750628d8 DN |
675 | /* Ci M Cj = Ci if (i == j) |
676 | Ci M Cj = VARYING if (i != j) */ | |
677 | if (simple_cst_equal (val1.const_val, val2.const_val) == 1) | |
678 | { | |
679 | result.lattice_val = CONSTANT; | |
680 | result.const_val = val1.const_val; | |
681 | } | |
682 | else | |
683 | { | |
684 | result.lattice_val = VARYING; | |
685 | result.const_val = NULL_TREE; | |
686 | } | |
4fa204da | 687 | |
750628d8 | 688 | return result; |
6de9cd9a DN |
689 | } |
690 | ||
691 | ||
750628d8 DN |
692 | /* Loop through the PHI_NODE's parameters for BLOCK and compare their |
693 | lattice values to determine PHI_NODE's lattice value. The value of a | |
694 | PHI node is determined calling ccp_lattice_meet() with all the arguments | |
695 | of the PHI node that are incoming via executable edges. */ | |
6de9cd9a | 696 | |
750628d8 DN |
697 | static enum ssa_prop_result |
698 | ccp_visit_phi_node (tree phi) | |
6de9cd9a | 699 | { |
750628d8 DN |
700 | value new_val, *old_val; |
701 | int i; | |
6de9cd9a | 702 | |
750628d8 | 703 | if (dump_file && (dump_flags & TDF_DETAILS)) |
6de9cd9a | 704 | { |
750628d8 DN |
705 | fprintf (dump_file, "\nVisiting PHI node: "); |
706 | print_generic_expr (dump_file, phi, dump_flags); | |
6de9cd9a | 707 | } |
6de9cd9a | 708 | |
750628d8 DN |
709 | old_val = get_value (PHI_RESULT (phi)); |
710 | switch (old_val->lattice_val) | |
711 | { | |
712 | case VARYING: | |
713 | return SSA_PROP_NOT_INTERESTING; | |
6de9cd9a | 714 | |
750628d8 DN |
715 | case CONSTANT: |
716 | new_val = *old_val; | |
717 | break; | |
6de9cd9a | 718 | |
750628d8 DN |
719 | case UNKNOWN_VAL: |
720 | /* To avoid the default value of UNKNOWN_VAL overriding | |
721 | that of its possible constant arguments, temporarily | |
722 | set the PHI node's default lattice value to be | |
723 | UNDEFINED. If the PHI node's old value was UNKNOWN_VAL and | |
724 | the new value is UNDEFINED, then we prevent the invalid | |
725 | transition by not calling set_lattice_value. */ | |
726 | new_val.lattice_val = UNDEFINED; | |
727 | new_val.const_val = NULL_TREE; | |
728 | break; | |
6de9cd9a | 729 | |
750628d8 DN |
730 | case UNDEFINED: |
731 | case UNINITIALIZED: | |
732 | new_val.lattice_val = UNDEFINED; | |
733 | new_val.const_val = NULL_TREE; | |
734 | break; | |
6de9cd9a | 735 | |
750628d8 | 736 | default: |
1e128c5f | 737 | gcc_unreachable (); |
750628d8 | 738 | } |
6de9cd9a | 739 | |
750628d8 DN |
740 | for (i = 0; i < PHI_NUM_ARGS (phi); i++) |
741 | { | |
742 | /* Compute the meet operator over all the PHI arguments. */ | |
743 | edge e = PHI_ARG_EDGE (phi, i); | |
6de9cd9a | 744 | |
750628d8 DN |
745 | if (dump_file && (dump_flags & TDF_DETAILS)) |
746 | { | |
747 | fprintf (dump_file, | |
748 | "\n Argument #%d (%d -> %d %sexecutable)\n", | |
749 | i, e->src->index, e->dest->index, | |
750 | (e->flags & EDGE_EXECUTABLE) ? "" : "not "); | |
751 | } | |
752 | ||
753 | /* If the incoming edge is executable, Compute the meet operator for | |
754 | the existing value of the PHI node and the current PHI argument. */ | |
755 | if (e->flags & EDGE_EXECUTABLE) | |
756 | { | |
757 | tree rdef = PHI_ARG_DEF (phi, i); | |
758 | value *rdef_val, val; | |
6de9cd9a | 759 | |
750628d8 DN |
760 | if (is_gimple_min_invariant (rdef)) |
761 | { | |
762 | val.lattice_val = CONSTANT; | |
763 | val.const_val = rdef; | |
764 | rdef_val = &val; | |
765 | } | |
766 | else | |
767 | rdef_val = get_value (rdef); | |
6de9cd9a | 768 | |
750628d8 | 769 | new_val = ccp_lattice_meet (new_val, *rdef_val); |
6de9cd9a | 770 | |
750628d8 DN |
771 | if (dump_file && (dump_flags & TDF_DETAILS)) |
772 | { | |
773 | fprintf (dump_file, "\t"); | |
774 | print_generic_expr (dump_file, rdef, dump_flags); | |
775 | dump_lattice_value (dump_file, "\tValue: ", *rdef_val); | |
776 | fprintf (dump_file, "\n"); | |
777 | } | |
6de9cd9a | 778 | |
750628d8 DN |
779 | if (new_val.lattice_val == VARYING) |
780 | break; | |
781 | } | |
782 | } | |
6de9cd9a DN |
783 | |
784 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
750628d8 DN |
785 | { |
786 | dump_lattice_value (dump_file, "\n PHI node value: ", new_val); | |
787 | fprintf (dump_file, "\n\n"); | |
788 | } | |
789 | ||
8c27b7d4 | 790 | /* Check for an invalid change from UNKNOWN_VAL to UNDEFINED. */ |
750628d8 DN |
791 | if (old_val->lattice_val == UNKNOWN_VAL |
792 | && new_val.lattice_val == UNDEFINED) | |
793 | return SSA_PROP_NOT_INTERESTING; | |
794 | ||
795 | /* Otherwise, make the transition to the new value. */ | |
796 | if (set_lattice_value (PHI_RESULT (phi), new_val)) | |
797 | { | |
798 | if (new_val.lattice_val == VARYING) | |
799 | return SSA_PROP_VARYING; | |
800 | else | |
801 | return SSA_PROP_INTERESTING; | |
802 | } | |
803 | else | |
804 | return SSA_PROP_NOT_INTERESTING; | |
6de9cd9a DN |
805 | } |
806 | ||
807 | ||
750628d8 DN |
808 | /* CCP specific front-end to the non-destructive constant folding |
809 | routines. | |
6de9cd9a DN |
810 | |
811 | Attempt to simplify the RHS of STMT knowing that one or more | |
812 | operands are constants. | |
813 | ||
814 | If simplification is possible, return the simplified RHS, | |
815 | otherwise return the original RHS. */ | |
816 | ||
817 | static tree | |
818 | ccp_fold (tree stmt) | |
819 | { | |
820 | tree rhs = get_rhs (stmt); | |
821 | enum tree_code code = TREE_CODE (rhs); | |
6615c446 | 822 | enum tree_code_class kind = TREE_CODE_CLASS (code); |
6de9cd9a | 823 | tree retval = NULL_TREE; |
173b818d BB |
824 | vuse_optype vuses; |
825 | ||
826 | vuses = STMT_VUSE_OPS (stmt); | |
6de9cd9a DN |
827 | |
828 | /* If the RHS is just a variable, then that variable must now have | |
829 | a constant value that we can return directly. */ | |
830 | if (TREE_CODE (rhs) == SSA_NAME) | |
831 | return get_value (rhs)->const_val; | |
173b818d BB |
832 | else if (DECL_P (rhs) |
833 | && NUM_VUSES (vuses) == 1 | |
834 | && rhs == SSA_NAME_VAR (VUSE_OP (vuses, 0))) | |
835 | return get_value (VUSE_OP (vuses, 0))->const_val; | |
6de9cd9a DN |
836 | |
837 | /* Unary operators. Note that we know the single operand must | |
838 | be a constant. So this should almost always return a | |
839 | simplified RHS. */ | |
6615c446 | 840 | if (kind == tcc_unary) |
6de9cd9a DN |
841 | { |
842 | /* Handle unary operators which can appear in GIMPLE form. */ | |
843 | tree op0 = TREE_OPERAND (rhs, 0); | |
844 | ||
845 | /* Simplify the operand down to a constant. */ | |
846 | if (TREE_CODE (op0) == SSA_NAME) | |
847 | { | |
848 | value *val = get_value (op0); | |
849 | if (val->lattice_val == CONSTANT) | |
850 | op0 = get_value (op0)->const_val; | |
851 | } | |
852 | ||
853 | retval = nondestructive_fold_unary_to_constant (code, | |
854 | TREE_TYPE (rhs), | |
855 | op0); | |
856 | ||
857 | /* If we folded, but did not create an invariant, then we can not | |
858 | use this expression. */ | |
859 | if (retval && ! is_gimple_min_invariant (retval)) | |
860 | return NULL; | |
861 | ||
862 | /* If we could not fold the expression, but the arguments are all | |
863 | constants and gimple values, then build and return the new | |
864 | expression. | |
865 | ||
866 | In some cases the new expression is still something we can | |
867 | use as a replacement for an argument. This happens with | |
868 | NOP conversions of types for example. | |
869 | ||
870 | In other cases the new expression can not be used as a | |
871 | replacement for an argument (as it would create non-gimple | |
872 | code). But the new expression can still be used to derive | |
873 | other constants. */ | |
874 | if (! retval && is_gimple_min_invariant (op0)) | |
875 | return build1 (code, TREE_TYPE (rhs), op0); | |
876 | } | |
877 | ||
878 | /* Binary and comparison operators. We know one or both of the | |
879 | operands are constants. */ | |
6615c446 JO |
880 | else if (kind == tcc_binary |
881 | || kind == tcc_comparison | |
6de9cd9a DN |
882 | || code == TRUTH_AND_EXPR |
883 | || code == TRUTH_OR_EXPR | |
884 | || code == TRUTH_XOR_EXPR) | |
885 | { | |
886 | /* Handle binary and comparison operators that can appear in | |
887 | GIMPLE form. */ | |
888 | tree op0 = TREE_OPERAND (rhs, 0); | |
889 | tree op1 = TREE_OPERAND (rhs, 1); | |
890 | ||
891 | /* Simplify the operands down to constants when appropriate. */ | |
892 | if (TREE_CODE (op0) == SSA_NAME) | |
893 | { | |
894 | value *val = get_value (op0); | |
895 | if (val->lattice_val == CONSTANT) | |
896 | op0 = val->const_val; | |
897 | } | |
898 | ||
899 | if (TREE_CODE (op1) == SSA_NAME) | |
900 | { | |
901 | value *val = get_value (op1); | |
902 | if (val->lattice_val == CONSTANT) | |
903 | op1 = val->const_val; | |
904 | } | |
905 | ||
906 | retval = nondestructive_fold_binary_to_constant (code, | |
907 | TREE_TYPE (rhs), | |
908 | op0, op1); | |
909 | ||
910 | /* If we folded, but did not create an invariant, then we can not | |
911 | use this expression. */ | |
912 | if (retval && ! is_gimple_min_invariant (retval)) | |
913 | return NULL; | |
914 | ||
915 | /* If we could not fold the expression, but the arguments are all | |
916 | constants and gimple values, then build and return the new | |
917 | expression. | |
918 | ||
919 | In some cases the new expression is still something we can | |
920 | use as a replacement for an argument. This happens with | |
921 | NOP conversions of types for example. | |
922 | ||
923 | In other cases the new expression can not be used as a | |
924 | replacement for an argument (as it would create non-gimple | |
925 | code). But the new expression can still be used to derive | |
926 | other constants. */ | |
927 | if (! retval | |
928 | && is_gimple_min_invariant (op0) | |
929 | && is_gimple_min_invariant (op1)) | |
930 | return build (code, TREE_TYPE (rhs), op0, op1); | |
931 | } | |
932 | ||
933 | /* We may be able to fold away calls to builtin functions if their | |
9cf737f8 | 934 | arguments are constants. */ |
6de9cd9a DN |
935 | else if (code == CALL_EXPR |
936 | && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR | |
937 | && (TREE_CODE (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)) | |
938 | == FUNCTION_DECL) | |
939 | && DECL_BUILT_IN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))) | |
940 | { | |
941 | use_optype uses = STMT_USE_OPS (stmt); | |
942 | if (NUM_USES (uses) != 0) | |
943 | { | |
944 | tree *orig; | |
945 | size_t i; | |
946 | ||
947 | /* Preserve the original values of every operand. */ | |
948 | orig = xmalloc (sizeof (tree) * NUM_USES (uses)); | |
949 | for (i = 0; i < NUM_USES (uses); i++) | |
950 | orig[i] = USE_OP (uses, i); | |
951 | ||
952 | /* Substitute operands with their values and try to fold. */ | |
953 | replace_uses_in (stmt, NULL); | |
a32e70c3 | 954 | retval = fold_builtin (rhs, false); |
6de9cd9a DN |
955 | |
956 | /* Restore operands to their original form. */ | |
957 | for (i = 0; i < NUM_USES (uses); i++) | |
d00ad49b | 958 | SET_USE_OP (uses, i, orig[i]); |
6de9cd9a DN |
959 | free (orig); |
960 | } | |
961 | } | |
962 | else | |
963 | return rhs; | |
964 | ||
965 | /* If we got a simplified form, see if we need to convert its type. */ | |
966 | if (retval) | |
a32e70c3 | 967 | return fold_convert (TREE_TYPE (rhs), retval); |
6de9cd9a DN |
968 | |
969 | /* No simplification was possible. */ | |
970 | return rhs; | |
971 | } | |
972 | ||
973 | ||
974 | /* Evaluate statement STMT. */ | |
975 | ||
976 | static value | |
977 | evaluate_stmt (tree stmt) | |
978 | { | |
979 | value val; | |
980 | tree simplified; | |
981 | latticevalue likelyvalue = likely_value (stmt); | |
982 | ||
983 | /* If the statement is likely to have a CONSTANT result, then try | |
984 | to fold the statement to determine the constant value. */ | |
985 | if (likelyvalue == CONSTANT) | |
986 | simplified = ccp_fold (stmt); | |
987 | /* If the statement is likely to have a VARYING result, then do not | |
988 | bother folding the statement. */ | |
989 | else if (likelyvalue == VARYING) | |
990 | simplified = get_rhs (stmt); | |
991 | /* Otherwise the statement is likely to have an UNDEFINED value and | |
992 | there will be nothing to do. */ | |
993 | else | |
994 | simplified = NULL_TREE; | |
995 | ||
996 | if (simplified && is_gimple_min_invariant (simplified)) | |
997 | { | |
998 | /* The statement produced a constant value. */ | |
999 | val.lattice_val = CONSTANT; | |
1000 | val.const_val = simplified; | |
1001 | } | |
1002 | else | |
1003 | { | |
1004 | /* The statement produced a nonconstant value. If the statement | |
173b818d BB |
1005 | had undefined or virtual operands, then the result of the |
1006 | statement should be undefined or virtual respectively. | |
1007 | Else the result of the statement is VARYING. */ | |
750628d8 DN |
1008 | val.lattice_val = (likelyvalue == UNDEFINED ? UNDEFINED : VARYING); |
1009 | val.lattice_val = (likelyvalue == UNKNOWN_VAL | |
1010 | ? UNKNOWN_VAL : val.lattice_val); | |
1011 | val.const_val = NULL_TREE; | |
6de9cd9a | 1012 | } |
750628d8 DN |
1013 | |
1014 | return val; | |
6de9cd9a DN |
1015 | } |
1016 | ||
1017 | ||
750628d8 DN |
1018 | /* Visit the assignment statement STMT. Set the value of its LHS to the |
1019 | value computed by the RHS and store LHS in *OUTPUT_P. */ | |
6de9cd9a | 1020 | |
750628d8 DN |
1021 | static enum ssa_prop_result |
1022 | visit_assignment (tree stmt, tree *output_p) | |
6de9cd9a | 1023 | { |
750628d8 DN |
1024 | value val; |
1025 | tree lhs, rhs; | |
1026 | vuse_optype vuses; | |
1027 | v_must_def_optype v_must_defs; | |
6de9cd9a | 1028 | |
750628d8 DN |
1029 | lhs = TREE_OPERAND (stmt, 0); |
1030 | rhs = TREE_OPERAND (stmt, 1); | |
1031 | vuses = STMT_VUSE_OPS (stmt); | |
1032 | v_must_defs = STMT_V_MUST_DEF_OPS (stmt); | |
6de9cd9a | 1033 | |
1e128c5f GB |
1034 | gcc_assert (NUM_V_MAY_DEFS (STMT_V_MAY_DEF_OPS (stmt)) == 0); |
1035 | gcc_assert (NUM_V_MUST_DEFS (v_must_defs) == 1 | |
1036 | || TREE_CODE (lhs) == SSA_NAME); | |
6de9cd9a | 1037 | |
750628d8 DN |
1038 | /* We require the SSA version number of the lhs for the value_vector. |
1039 | Make sure we have it. */ | |
1040 | if (TREE_CODE (lhs) != SSA_NAME) | |
1041 | { | |
1042 | /* If we make it here, then stmt only has one definition: | |
1043 | a V_MUST_DEF. */ | |
1044 | lhs = V_MUST_DEF_OP (v_must_defs, 0); | |
1045 | } | |
6de9cd9a | 1046 | |
750628d8 DN |
1047 | if (TREE_CODE (rhs) == SSA_NAME) |
1048 | { | |
1049 | /* For a simple copy operation, we copy the lattice values. */ | |
1050 | value *nval = get_value (rhs); | |
1051 | val = *nval; | |
1052 | } | |
1053 | else if (DECL_P (rhs) | |
1054 | && NUM_VUSES (vuses) == 1 | |
1055 | && rhs == SSA_NAME_VAR (VUSE_OP (vuses, 0))) | |
1056 | { | |
1057 | /* Same as above, but the rhs is not a gimple register and yet | |
1058 | has a known VUSE. */ | |
1059 | value *nval = get_value (VUSE_OP (vuses, 0)); | |
1060 | val = *nval; | |
1061 | } | |
1062 | else | |
1063 | { | |
1064 | /* Evaluate the statement. */ | |
1065 | val = evaluate_stmt (stmt); | |
1066 | } | |
6de9cd9a | 1067 | |
750628d8 DN |
1068 | /* FIXME: Hack. If this was a definition of a bitfield, we need to widen |
1069 | the constant value into the type of the destination variable. This | |
1070 | should not be necessary if GCC represented bitfields properly. */ | |
1071 | { | |
1072 | tree lhs = TREE_OPERAND (stmt, 0); | |
1073 | if (val.lattice_val == CONSTANT | |
1074 | && TREE_CODE (lhs) == COMPONENT_REF | |
1075 | && DECL_BIT_FIELD (TREE_OPERAND (lhs, 1))) | |
6de9cd9a | 1076 | { |
750628d8 DN |
1077 | tree w = widen_bitfield (val.const_val, TREE_OPERAND (lhs, 1), lhs); |
1078 | ||
1079 | if (w && is_gimple_min_invariant (w)) | |
1080 | val.const_val = w; | |
1081 | else | |
6de9cd9a | 1082 | { |
750628d8 DN |
1083 | val.lattice_val = VARYING; |
1084 | val.const_val = NULL; | |
6de9cd9a | 1085 | } |
6de9cd9a | 1086 | } |
750628d8 | 1087 | } |
6de9cd9a | 1088 | |
750628d8 | 1089 | /* If LHS is not a gimple register, then it cannot take on an |
8c27b7d4 | 1090 | UNDEFINED value. */ |
750628d8 DN |
1091 | if (!is_gimple_reg (SSA_NAME_VAR (lhs)) |
1092 | && val.lattice_val == UNDEFINED) | |
1093 | val.lattice_val = UNKNOWN_VAL; | |
6de9cd9a | 1094 | |
750628d8 DN |
1095 | /* Set the lattice value of the statement's output. */ |
1096 | if (set_lattice_value (lhs, val)) | |
6de9cd9a | 1097 | { |
750628d8 DN |
1098 | *output_p = lhs; |
1099 | if (val.lattice_val == VARYING) | |
1100 | return SSA_PROP_VARYING; | |
1101 | else | |
1102 | return SSA_PROP_INTERESTING; | |
6de9cd9a | 1103 | } |
750628d8 DN |
1104 | else |
1105 | return SSA_PROP_NOT_INTERESTING; | |
6de9cd9a DN |
1106 | } |
1107 | ||
6de9cd9a | 1108 | |
750628d8 DN |
1109 | /* Visit the conditional statement STMT. Return SSA_PROP_INTERESTING |
1110 | if it can determine which edge will be taken. Otherwise, return | |
1111 | SSA_PROP_VARYING. */ | |
1112 | ||
1113 | static enum ssa_prop_result | |
1114 | visit_cond_stmt (tree stmt, edge *taken_edge_p) | |
6de9cd9a DN |
1115 | { |
1116 | value val; | |
750628d8 DN |
1117 | basic_block block; |
1118 | ||
1119 | block = bb_for_stmt (stmt); | |
1120 | val = evaluate_stmt (stmt); | |
1121 | ||
1122 | /* Find which edge out of the conditional block will be taken and add it | |
1123 | to the worklist. If no single edge can be determined statically, | |
1124 | return SSA_PROP_VARYING to feed all the outgoing edges to the | |
1125 | propagation engine. */ | |
1126 | *taken_edge_p = find_taken_edge (block, val.const_val); | |
1127 | if (*taken_edge_p) | |
1128 | return SSA_PROP_INTERESTING; | |
1129 | else | |
1130 | return SSA_PROP_VARYING; | |
6de9cd9a DN |
1131 | } |
1132 | ||
6de9cd9a | 1133 | |
750628d8 DN |
1134 | /* Evaluate statement STMT. If the statement produces an output value and |
1135 | its evaluation changes the lattice value of its output, return | |
1136 | SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the | |
1137 | output value. | |
1138 | ||
1139 | If STMT is a conditional branch and we can determine its truth | |
1140 | value, set *TAKEN_EDGE_P accordingly. If STMT produces a varying | |
1141 | value, return SSA_PROP_VARYING. */ | |
6de9cd9a | 1142 | |
750628d8 DN |
1143 | static enum ssa_prop_result |
1144 | ccp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p) | |
1145 | { | |
1146 | stmt_ann_t ann; | |
1147 | v_may_def_optype v_may_defs; | |
1148 | v_must_def_optype v_must_defs; | |
1149 | tree def; | |
1150 | ssa_op_iter iter; | |
6de9cd9a | 1151 | |
750628d8 | 1152 | if (dump_file && (dump_flags & TDF_DETAILS)) |
6de9cd9a | 1153 | { |
750628d8 DN |
1154 | fprintf (dump_file, "\nVisiting statement: "); |
1155 | print_generic_stmt (dump_file, stmt, TDF_SLIM); | |
1156 | fprintf (dump_file, "\n"); | |
6de9cd9a | 1157 | } |
6de9cd9a | 1158 | |
750628d8 DN |
1159 | ann = stmt_ann (stmt); |
1160 | ||
1161 | v_must_defs = V_MUST_DEF_OPS (ann); | |
1162 | v_may_defs = V_MAY_DEF_OPS (ann); | |
1163 | if (TREE_CODE (stmt) == MODIFY_EXPR | |
1164 | && NUM_V_MAY_DEFS (v_may_defs) == 0 | |
1165 | && (NUM_V_MUST_DEFS (v_must_defs) == 1 | |
1166 | || TREE_CODE (TREE_OPERAND (stmt, 0)) == SSA_NAME)) | |
6de9cd9a | 1167 | { |
750628d8 DN |
1168 | /* If the statement is an assignment that produces a single |
1169 | output value, evaluate its RHS to see if the lattice value of | |
1170 | its output has changed. */ | |
1171 | return visit_assignment (stmt, output_p); | |
6de9cd9a | 1172 | } |
750628d8 | 1173 | else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR) |
6de9cd9a | 1174 | { |
750628d8 DN |
1175 | /* If STMT is a conditional branch, see if we can determine |
1176 | which branch will be taken. */ | |
1177 | return visit_cond_stmt (stmt, taken_edge_p); | |
6de9cd9a | 1178 | } |
6de9cd9a | 1179 | |
750628d8 DN |
1180 | /* Any other kind of statement is not interesting for constant |
1181 | propagation and, therefore, not worth simulating. */ | |
750628d8 DN |
1182 | if (dump_file && (dump_flags & TDF_DETAILS)) |
1183 | fprintf (dump_file, "No interesting values produced. Marked VARYING.\n"); | |
6de9cd9a | 1184 | |
750628d8 DN |
1185 | /* Definitions made by statements other than assignments to |
1186 | SSA_NAMEs represent unknown modifications to their outputs. | |
1187 | Mark them VARYING. */ | |
1188 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) | |
1189 | def_to_varying (def); | |
6de9cd9a | 1190 | |
750628d8 DN |
1191 | /* Mark all V_MAY_DEF operands VARYING. */ |
1192 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_VMAYDEF) | |
1193 | def_to_varying (def); | |
6de9cd9a | 1194 | |
750628d8 DN |
1195 | return SSA_PROP_VARYING; |
1196 | } | |
6de9cd9a | 1197 | |
6de9cd9a | 1198 | |
750628d8 | 1199 | /* Main entry point for SSA Conditional Constant Propagation. |
6de9cd9a | 1200 | |
750628d8 DN |
1201 | [ DESCRIBE MAIN ALGORITHM HERE ] */ |
1202 | ||
1203 | static void | |
1204 | execute_ssa_ccp (void) | |
1205 | { | |
1206 | ccp_initialize (); | |
1207 | ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node); | |
1208 | ccp_finalize (); | |
6de9cd9a DN |
1209 | } |
1210 | ||
173b818d BB |
1211 | |
1212 | static bool | |
750628d8 | 1213 | gate_ccp (void) |
173b818d | 1214 | { |
750628d8 | 1215 | return flag_tree_ccp != 0; |
173b818d BB |
1216 | } |
1217 | ||
6de9cd9a | 1218 | |
750628d8 DN |
1219 | struct tree_opt_pass pass_ccp = |
1220 | { | |
1221 | "ccp", /* name */ | |
1222 | gate_ccp, /* gate */ | |
1223 | execute_ssa_ccp, /* execute */ | |
1224 | NULL, /* sub */ | |
1225 | NULL, /* next */ | |
1226 | 0, /* static_pass_number */ | |
1227 | TV_TREE_CCP, /* tv_id */ | |
1228 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ | |
1229 | 0, /* properties_provided */ | |
1230 | 0, /* properties_destroyed */ | |
1231 | 0, /* todo_flags_start */ | |
1232 | TODO_dump_func | TODO_rename_vars | |
1233 | | TODO_ggc_collect | TODO_verify_ssa | |
9f8628ba PB |
1234 | | TODO_verify_stmts, /* todo_flags_finish */ |
1235 | 0 /* letter */ | |
750628d8 | 1236 | }; |
6de9cd9a | 1237 | |
6de9cd9a | 1238 | |
750628d8 DN |
1239 | /* Given a constant value VAL for bitfield FIELD, and a destination |
1240 | variable VAR, return VAL appropriately widened to fit into VAR. If | |
1241 | FIELD is wider than HOST_WIDE_INT, NULL is returned. */ | |
6de9cd9a | 1242 | |
750628d8 DN |
1243 | tree |
1244 | widen_bitfield (tree val, tree field, tree var) | |
6de9cd9a | 1245 | { |
750628d8 DN |
1246 | unsigned HOST_WIDE_INT var_size, field_size; |
1247 | tree wide_val; | |
1248 | unsigned HOST_WIDE_INT mask; | |
1249 | unsigned int i; | |
6de9cd9a | 1250 | |
750628d8 DN |
1251 | /* We can only do this if the size of the type and field and VAL are |
1252 | all constants representable in HOST_WIDE_INT. */ | |
1253 | if (!host_integerp (TYPE_SIZE (TREE_TYPE (var)), 1) | |
1254 | || !host_integerp (DECL_SIZE (field), 1) | |
1255 | || !host_integerp (val, 0)) | |
1256 | return NULL_TREE; | |
6de9cd9a | 1257 | |
750628d8 DN |
1258 | var_size = tree_low_cst (TYPE_SIZE (TREE_TYPE (var)), 1); |
1259 | field_size = tree_low_cst (DECL_SIZE (field), 1); | |
6de9cd9a | 1260 | |
750628d8 DN |
1261 | /* Give up if either the bitfield or the variable are too wide. */ |
1262 | if (field_size > HOST_BITS_PER_WIDE_INT || var_size > HOST_BITS_PER_WIDE_INT) | |
1263 | return NULL_TREE; | |
6de9cd9a | 1264 | |
1e128c5f | 1265 | gcc_assert (var_size >= field_size); |
6de9cd9a | 1266 | |
750628d8 DN |
1267 | /* If the sign bit of the value is not set or the field's type is unsigned, |
1268 | just mask off the high order bits of the value. */ | |
1269 | if (DECL_UNSIGNED (field) | |
1270 | || !(tree_low_cst (val, 0) & (((HOST_WIDE_INT)1) << (field_size - 1)))) | |
1271 | { | |
1272 | /* Zero extension. Build a mask with the lower 'field_size' bits | |
1273 | set and a BIT_AND_EXPR node to clear the high order bits of | |
1274 | the value. */ | |
1275 | for (i = 0, mask = 0; i < field_size; i++) | |
1276 | mask |= ((HOST_WIDE_INT) 1) << i; | |
6de9cd9a | 1277 | |
750628d8 DN |
1278 | wide_val = build (BIT_AND_EXPR, TREE_TYPE (var), val, |
1279 | fold_convert (TREE_TYPE (var), | |
1280 | build_int_cst (NULL_TREE, mask))); | |
6de9cd9a | 1281 | } |
750628d8 | 1282 | else |
173b818d | 1283 | { |
750628d8 DN |
1284 | /* Sign extension. Create a mask with the upper 'field_size' |
1285 | bits set and a BIT_IOR_EXPR to set the high order bits of the | |
1286 | value. */ | |
1287 | for (i = 0, mask = 0; i < (var_size - field_size); i++) | |
1288 | mask |= ((HOST_WIDE_INT) 1) << (var_size - i - 1); | |
1289 | ||
1290 | wide_val = build (BIT_IOR_EXPR, TREE_TYPE (var), val, | |
1291 | fold_convert (TREE_TYPE (var), | |
1292 | build_int_cst (NULL_TREE, mask))); | |
173b818d | 1293 | } |
6de9cd9a | 1294 | |
750628d8 | 1295 | return fold (wide_val); |
6de9cd9a DN |
1296 | } |
1297 | ||
750628d8 | 1298 | |
6de9cd9a DN |
1299 | /* A subroutine of fold_stmt_r. Attempts to fold *(A+O) to A[X]. |
1300 | BASE is an array type. OFFSET is a byte displacement. ORIG_TYPE | |
9cf737f8 | 1301 | is the desired result type. */ |
6de9cd9a DN |
1302 | |
1303 | static tree | |
1304 | maybe_fold_offset_to_array_ref (tree base, tree offset, tree orig_type) | |
1305 | { | |
44de5aeb RK |
1306 | tree min_idx, idx, elt_offset = integer_zero_node; |
1307 | tree array_type, elt_type, elt_size; | |
1308 | ||
1309 | /* If BASE is an ARRAY_REF, we can pick up another offset (this time | |
1310 | measured in units of the size of elements type) from that ARRAY_REF). | |
1311 | We can't do anything if either is variable. | |
1312 | ||
1313 | The case we handle here is *(&A[N]+O). */ | |
1314 | if (TREE_CODE (base) == ARRAY_REF) | |
1315 | { | |
1316 | tree low_bound = array_ref_low_bound (base); | |
1317 | ||
1318 | elt_offset = TREE_OPERAND (base, 1); | |
1319 | if (TREE_CODE (low_bound) != INTEGER_CST | |
1320 | || TREE_CODE (elt_offset) != INTEGER_CST) | |
1321 | return NULL_TREE; | |
1322 | ||
1323 | elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0); | |
1324 | base = TREE_OPERAND (base, 0); | |
1325 | } | |
6de9cd9a DN |
1326 | |
1327 | /* Ignore stupid user tricks of indexing non-array variables. */ | |
1328 | array_type = TREE_TYPE (base); | |
1329 | if (TREE_CODE (array_type) != ARRAY_TYPE) | |
1330 | return NULL_TREE; | |
1331 | elt_type = TREE_TYPE (array_type); | |
1332 | if (!lang_hooks.types_compatible_p (orig_type, elt_type)) | |
1333 | return NULL_TREE; | |
1334 | ||
44de5aeb RK |
1335 | /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the |
1336 | element type (so we can use the alignment if it's not constant). | |
1337 | Otherwise, compute the offset as an index by using a division. If the | |
1338 | division isn't exact, then don't do anything. */ | |
6de9cd9a | 1339 | elt_size = TYPE_SIZE_UNIT (elt_type); |
44de5aeb RK |
1340 | if (integer_zerop (offset)) |
1341 | { | |
1342 | if (TREE_CODE (elt_size) != INTEGER_CST) | |
1343 | elt_size = size_int (TYPE_ALIGN (elt_type)); | |
6de9cd9a | 1344 | |
44de5aeb RK |
1345 | idx = integer_zero_node; |
1346 | } | |
1347 | else | |
1348 | { | |
1349 | unsigned HOST_WIDE_INT lquo, lrem; | |
1350 | HOST_WIDE_INT hquo, hrem; | |
1351 | ||
1352 | if (TREE_CODE (elt_size) != INTEGER_CST | |
1353 | || div_and_round_double (TRUNC_DIV_EXPR, 1, | |
1354 | TREE_INT_CST_LOW (offset), | |
1355 | TREE_INT_CST_HIGH (offset), | |
1356 | TREE_INT_CST_LOW (elt_size), | |
1357 | TREE_INT_CST_HIGH (elt_size), | |
1358 | &lquo, &hquo, &lrem, &hrem) | |
1359 | || lrem || hrem) | |
1360 | return NULL_TREE; | |
6de9cd9a | 1361 | |
7d60be94 | 1362 | idx = build_int_cst_wide (NULL_TREE, lquo, hquo); |
44de5aeb RK |
1363 | } |
1364 | ||
1365 | /* Assume the low bound is zero. If there is a domain type, get the | |
1366 | low bound, if any, convert the index into that type, and add the | |
1367 | low bound. */ | |
1368 | min_idx = integer_zero_node; | |
1369 | if (TYPE_DOMAIN (array_type)) | |
6de9cd9a | 1370 | { |
44de5aeb RK |
1371 | if (TYPE_MIN_VALUE (TYPE_DOMAIN (array_type))) |
1372 | min_idx = TYPE_MIN_VALUE (TYPE_DOMAIN (array_type)); | |
1373 | else | |
1374 | min_idx = fold_convert (TYPE_DOMAIN (array_type), min_idx); | |
1375 | ||
1376 | if (TREE_CODE (min_idx) != INTEGER_CST) | |
1377 | return NULL_TREE; | |
1378 | ||
1379 | idx = fold_convert (TYPE_DOMAIN (array_type), idx); | |
1380 | elt_offset = fold_convert (TYPE_DOMAIN (array_type), elt_offset); | |
6de9cd9a DN |
1381 | } |
1382 | ||
44de5aeb RK |
1383 | if (!integer_zerop (min_idx)) |
1384 | idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0); | |
1385 | if (!integer_zerop (elt_offset)) | |
1386 | idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0); | |
1387 | ||
1388 | return build (ARRAY_REF, orig_type, base, idx, min_idx, | |
1389 | size_int (tree_low_cst (elt_size, 1) | |
a4e9ffe5 | 1390 | / (TYPE_ALIGN_UNIT (elt_type)))); |
6de9cd9a DN |
1391 | } |
1392 | ||
750628d8 | 1393 | |
6de9cd9a DN |
1394 | /* A subroutine of fold_stmt_r. Attempts to fold *(S+O) to S.X. |
1395 | BASE is a record type. OFFSET is a byte displacement. ORIG_TYPE | |
1396 | is the desired result type. */ | |
1397 | /* ??? This doesn't handle class inheritance. */ | |
1398 | ||
1399 | static tree | |
1400 | maybe_fold_offset_to_component_ref (tree record_type, tree base, tree offset, | |
1401 | tree orig_type, bool base_is_ptr) | |
1402 | { | |
f34fa464 | 1403 | tree f, t, field_type, tail_array_field, field_offset; |
6de9cd9a DN |
1404 | |
1405 | if (TREE_CODE (record_type) != RECORD_TYPE | |
1406 | && TREE_CODE (record_type) != UNION_TYPE | |
1407 | && TREE_CODE (record_type) != QUAL_UNION_TYPE) | |
1408 | return NULL_TREE; | |
1409 | ||
1410 | /* Short-circuit silly cases. */ | |
1411 | if (lang_hooks.types_compatible_p (record_type, orig_type)) | |
1412 | return NULL_TREE; | |
1413 | ||
1414 | tail_array_field = NULL_TREE; | |
1415 | for (f = TYPE_FIELDS (record_type); f ; f = TREE_CHAIN (f)) | |
1416 | { | |
1417 | int cmp; | |
1418 | ||
1419 | if (TREE_CODE (f) != FIELD_DECL) | |
1420 | continue; | |
1421 | if (DECL_BIT_FIELD (f)) | |
1422 | continue; | |
f34fa464 ZD |
1423 | |
1424 | field_offset = byte_position (f); | |
1425 | if (TREE_CODE (field_offset) != INTEGER_CST) | |
6de9cd9a DN |
1426 | continue; |
1427 | ||
1428 | /* ??? Java creates "interesting" fields for representing base classes. | |
1429 | They have no name, and have no context. With no context, we get into | |
1430 | trouble with nonoverlapping_component_refs_p. Skip them. */ | |
1431 | if (!DECL_FIELD_CONTEXT (f)) | |
1432 | continue; | |
1433 | ||
1434 | /* The previous array field isn't at the end. */ | |
1435 | tail_array_field = NULL_TREE; | |
1436 | ||
1437 | /* Check to see if this offset overlaps with the field. */ | |
f34fa464 | 1438 | cmp = tree_int_cst_compare (field_offset, offset); |
6de9cd9a DN |
1439 | if (cmp > 0) |
1440 | continue; | |
1441 | ||
1442 | field_type = TREE_TYPE (f); | |
1443 | if (cmp < 0) | |
1444 | { | |
1445 | /* Don't care about offsets into the middle of scalars. */ | |
1446 | if (!AGGREGATE_TYPE_P (field_type)) | |
1447 | continue; | |
1448 | ||
1449 | /* Check for array at the end of the struct. This is often | |
1450 | used as for flexible array members. We should be able to | |
1451 | turn this into an array access anyway. */ | |
1452 | if (TREE_CODE (field_type) == ARRAY_TYPE) | |
1453 | tail_array_field = f; | |
1454 | ||
1455 | /* Check the end of the field against the offset. */ | |
1456 | if (!DECL_SIZE_UNIT (f) | |
1457 | || TREE_CODE (DECL_SIZE_UNIT (f)) != INTEGER_CST) | |
1458 | continue; | |
1459 | t = int_const_binop (MINUS_EXPR, offset, DECL_FIELD_OFFSET (f), 1); | |
1460 | if (!tree_int_cst_lt (t, DECL_SIZE_UNIT (f))) | |
1461 | continue; | |
1462 | ||
1463 | /* If we matched, then set offset to the displacement into | |
1464 | this field. */ | |
1465 | offset = t; | |
1466 | } | |
1467 | ||
1468 | /* Here we exactly match the offset being checked. If the types match, | |
1469 | then we can return that field. */ | |
1470 | else if (lang_hooks.types_compatible_p (orig_type, field_type)) | |
1471 | { | |
1472 | if (base_is_ptr) | |
1473 | base = build1 (INDIRECT_REF, record_type, base); | |
44de5aeb | 1474 | t = build (COMPONENT_REF, field_type, base, f, NULL_TREE); |
6de9cd9a DN |
1475 | return t; |
1476 | } | |
1477 | ||
1478 | /* Don't care about type-punning of scalars. */ | |
1479 | else if (!AGGREGATE_TYPE_P (field_type)) | |
1480 | return NULL_TREE; | |
1481 | ||
1482 | goto found; | |
1483 | } | |
1484 | ||
1485 | if (!tail_array_field) | |
1486 | return NULL_TREE; | |
1487 | ||
1488 | f = tail_array_field; | |
1489 | field_type = TREE_TYPE (f); | |
1490 | ||
1491 | found: | |
1492 | /* If we get here, we've got an aggregate field, and a possibly | |
1ea7e6ad | 1493 | nonzero offset into them. Recurse and hope for a valid match. */ |
6de9cd9a DN |
1494 | if (base_is_ptr) |
1495 | base = build1 (INDIRECT_REF, record_type, base); | |
44de5aeb | 1496 | base = build (COMPONENT_REF, field_type, base, f, NULL_TREE); |
6de9cd9a DN |
1497 | |
1498 | t = maybe_fold_offset_to_array_ref (base, offset, orig_type); | |
1499 | if (t) | |
1500 | return t; | |
1501 | return maybe_fold_offset_to_component_ref (field_type, base, offset, | |
1502 | orig_type, false); | |
1503 | } | |
1504 | ||
750628d8 | 1505 | |
6de9cd9a DN |
1506 | /* A subroutine of fold_stmt_r. Attempt to simplify *(BASE+OFFSET). |
1507 | Return the simplified expression, or NULL if nothing could be done. */ | |
1508 | ||
1509 | static tree | |
1510 | maybe_fold_stmt_indirect (tree expr, tree base, tree offset) | |
1511 | { | |
1512 | tree t; | |
1513 | ||
1514 | /* We may well have constructed a double-nested PLUS_EXPR via multiple | |
1515 | substitutions. Fold that down to one. Remove NON_LVALUE_EXPRs that | |
1516 | are sometimes added. */ | |
1517 | base = fold (base); | |
1518 | STRIP_NOPS (base); | |
1519 | TREE_OPERAND (expr, 0) = base; | |
1520 | ||
1521 | /* One possibility is that the address reduces to a string constant. */ | |
1522 | t = fold_read_from_constant_string (expr); | |
1523 | if (t) | |
1524 | return t; | |
1525 | ||
1526 | /* Add in any offset from a PLUS_EXPR. */ | |
1527 | if (TREE_CODE (base) == PLUS_EXPR) | |
1528 | { | |
1529 | tree offset2; | |
1530 | ||
1531 | offset2 = TREE_OPERAND (base, 1); | |
1532 | if (TREE_CODE (offset2) != INTEGER_CST) | |
1533 | return NULL_TREE; | |
1534 | base = TREE_OPERAND (base, 0); | |
1535 | ||
1536 | offset = int_const_binop (PLUS_EXPR, offset, offset2, 1); | |
1537 | } | |
1538 | ||
1539 | if (TREE_CODE (base) == ADDR_EXPR) | |
1540 | { | |
1541 | /* Strip the ADDR_EXPR. */ | |
1542 | base = TREE_OPERAND (base, 0); | |
1543 | ||
0534fa56 RH |
1544 | /* Fold away CONST_DECL to its value, if the type is scalar. */ |
1545 | if (TREE_CODE (base) == CONST_DECL | |
1546 | && is_gimple_min_invariant (DECL_INITIAL (base))) | |
1547 | return DECL_INITIAL (base); | |
1548 | ||
6de9cd9a DN |
1549 | /* Try folding *(&B+O) to B[X]. */ |
1550 | t = maybe_fold_offset_to_array_ref (base, offset, TREE_TYPE (expr)); | |
1551 | if (t) | |
1552 | return t; | |
1553 | ||
1554 | /* Try folding *(&B+O) to B.X. */ | |
1555 | t = maybe_fold_offset_to_component_ref (TREE_TYPE (base), base, offset, | |
1556 | TREE_TYPE (expr), false); | |
1557 | if (t) | |
1558 | return t; | |
1559 | ||
44de5aeb RK |
1560 | /* Fold *&B to B. We can only do this if EXPR is the same type |
1561 | as BASE. We can't do this if EXPR is the element type of an array | |
1562 | and BASE is the array. */ | |
1563 | if (integer_zerop (offset) | |
1564 | && lang_hooks.types_compatible_p (TREE_TYPE (base), | |
1565 | TREE_TYPE (expr))) | |
6de9cd9a DN |
1566 | return base; |
1567 | } | |
1568 | else | |
1569 | { | |
1570 | /* We can get here for out-of-range string constant accesses, | |
1571 | such as "_"[3]. Bail out of the entire substitution search | |
1572 | and arrange for the entire statement to be replaced by a | |
1573 | call to __builtin_trap. In all likelyhood this will all be | |
1574 | constant-folded away, but in the meantime we can't leave with | |
1575 | something that get_expr_operands can't understand. */ | |
1576 | ||
1577 | t = base; | |
1578 | STRIP_NOPS (t); | |
1579 | if (TREE_CODE (t) == ADDR_EXPR | |
1580 | && TREE_CODE (TREE_OPERAND (t, 0)) == STRING_CST) | |
1581 | { | |
1582 | /* FIXME: Except that this causes problems elsewhere with dead | |
1583 | code not being deleted, and we abort in the rtl expanders | |
1584 | because we failed to remove some ssa_name. In the meantime, | |
1585 | just return zero. */ | |
1586 | /* FIXME2: This condition should be signaled by | |
1587 | fold_read_from_constant_string directly, rather than | |
1588 | re-checking for it here. */ | |
1589 | return integer_zero_node; | |
1590 | } | |
1591 | ||
1592 | /* Try folding *(B+O) to B->X. Still an improvement. */ | |
1593 | if (POINTER_TYPE_P (TREE_TYPE (base))) | |
1594 | { | |
1595 | t = maybe_fold_offset_to_component_ref (TREE_TYPE (TREE_TYPE (base)), | |
1596 | base, offset, | |
1597 | TREE_TYPE (expr), true); | |
1598 | if (t) | |
1599 | return t; | |
1600 | } | |
1601 | } | |
1602 | ||
1603 | /* Otherwise we had an offset that we could not simplify. */ | |
1604 | return NULL_TREE; | |
1605 | } | |
1606 | ||
750628d8 | 1607 | |
6de9cd9a DN |
1608 | /* A subroutine of fold_stmt_r. EXPR is a PLUS_EXPR. |
1609 | ||
1610 | A quaint feature extant in our address arithmetic is that there | |
1611 | can be hidden type changes here. The type of the result need | |
1612 | not be the same as the type of the input pointer. | |
1613 | ||
1614 | What we're after here is an expression of the form | |
1615 | (T *)(&array + const) | |
1616 | where the cast doesn't actually exist, but is implicit in the | |
1617 | type of the PLUS_EXPR. We'd like to turn this into | |
1618 | &array[x] | |
1619 | which may be able to propagate further. */ | |
1620 | ||
1621 | static tree | |
1622 | maybe_fold_stmt_addition (tree expr) | |
1623 | { | |
1624 | tree op0 = TREE_OPERAND (expr, 0); | |
1625 | tree op1 = TREE_OPERAND (expr, 1); | |
1626 | tree ptr_type = TREE_TYPE (expr); | |
1627 | tree ptd_type; | |
1628 | tree t; | |
1629 | bool subtract = (TREE_CODE (expr) == MINUS_EXPR); | |
1630 | ||
1631 | /* We're only interested in pointer arithmetic. */ | |
1632 | if (!POINTER_TYPE_P (ptr_type)) | |
1633 | return NULL_TREE; | |
1634 | /* Canonicalize the integral operand to op1. */ | |
1635 | if (INTEGRAL_TYPE_P (TREE_TYPE (op0))) | |
1636 | { | |
1637 | if (subtract) | |
1638 | return NULL_TREE; | |
1639 | t = op0, op0 = op1, op1 = t; | |
1640 | } | |
1641 | /* It had better be a constant. */ | |
1642 | if (TREE_CODE (op1) != INTEGER_CST) | |
1643 | return NULL_TREE; | |
1644 | /* The first operand should be an ADDR_EXPR. */ | |
1645 | if (TREE_CODE (op0) != ADDR_EXPR) | |
1646 | return NULL_TREE; | |
1647 | op0 = TREE_OPERAND (op0, 0); | |
1648 | ||
1649 | /* If the first operand is an ARRAY_REF, expand it so that we can fold | |
1650 | the offset into it. */ | |
1651 | while (TREE_CODE (op0) == ARRAY_REF) | |
1652 | { | |
1653 | tree array_obj = TREE_OPERAND (op0, 0); | |
1654 | tree array_idx = TREE_OPERAND (op0, 1); | |
1655 | tree elt_type = TREE_TYPE (op0); | |
1656 | tree elt_size = TYPE_SIZE_UNIT (elt_type); | |
1657 | tree min_idx; | |
1658 | ||
1659 | if (TREE_CODE (array_idx) != INTEGER_CST) | |
1660 | break; | |
1661 | if (TREE_CODE (elt_size) != INTEGER_CST) | |
1662 | break; | |
1663 | ||
1664 | /* Un-bias the index by the min index of the array type. */ | |
1665 | min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj)); | |
1666 | if (min_idx) | |
1667 | { | |
1668 | min_idx = TYPE_MIN_VALUE (min_idx); | |
1669 | if (min_idx) | |
1670 | { | |
44de5aeb RK |
1671 | if (TREE_CODE (min_idx) != INTEGER_CST) |
1672 | break; | |
1673 | ||
6de9cd9a DN |
1674 | array_idx = convert (TREE_TYPE (min_idx), array_idx); |
1675 | if (!integer_zerop (min_idx)) | |
1676 | array_idx = int_const_binop (MINUS_EXPR, array_idx, | |
1677 | min_idx, 0); | |
1678 | } | |
1679 | } | |
1680 | ||
1681 | /* Convert the index to a byte offset. */ | |
1682 | array_idx = convert (sizetype, array_idx); | |
1683 | array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0); | |
1684 | ||
1685 | /* Update the operands for the next round, or for folding. */ | |
1686 | /* If we're manipulating unsigned types, then folding into negative | |
1687 | values can produce incorrect results. Particularly if the type | |
1688 | is smaller than the width of the pointer. */ | |
1689 | if (subtract | |
1690 | && TYPE_UNSIGNED (TREE_TYPE (op1)) | |
1691 | && tree_int_cst_lt (array_idx, op1)) | |
1692 | return NULL; | |
1693 | op1 = int_const_binop (subtract ? MINUS_EXPR : PLUS_EXPR, | |
1694 | array_idx, op1, 0); | |
1695 | subtract = false; | |
1696 | op0 = array_obj; | |
1697 | } | |
1698 | ||
1699 | /* If we weren't able to fold the subtraction into another array reference, | |
1700 | canonicalize the integer for passing to the array and component ref | |
1701 | simplification functions. */ | |
1702 | if (subtract) | |
1703 | { | |
1704 | if (TYPE_UNSIGNED (TREE_TYPE (op1))) | |
1705 | return NULL; | |
1706 | op1 = fold (build1 (NEGATE_EXPR, TREE_TYPE (op1), op1)); | |
1707 | /* ??? In theory fold should always produce another integer. */ | |
1708 | if (TREE_CODE (op1) != INTEGER_CST) | |
1709 | return NULL; | |
1710 | } | |
1711 | ||
1712 | ptd_type = TREE_TYPE (ptr_type); | |
1713 | ||
1714 | /* At which point we can try some of the same things as for indirects. */ | |
1715 | t = maybe_fold_offset_to_array_ref (op0, op1, ptd_type); | |
1716 | if (!t) | |
1717 | t = maybe_fold_offset_to_component_ref (TREE_TYPE (op0), op0, op1, | |
1718 | ptd_type, false); | |
1719 | if (t) | |
1720 | t = build1 (ADDR_EXPR, ptr_type, t); | |
1721 | ||
1722 | return t; | |
1723 | } | |
1724 | ||
750628d8 | 1725 | |
6de9cd9a DN |
1726 | /* Subroutine of fold_stmt called via walk_tree. We perform several |
1727 | simplifications of EXPR_P, mostly having to do with pointer arithmetic. */ | |
1728 | ||
1729 | static tree | |
1730 | fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data) | |
1731 | { | |
1732 | bool *changed_p = data; | |
1733 | tree expr = *expr_p, t; | |
1734 | ||
1735 | /* ??? It'd be nice if walk_tree had a pre-order option. */ | |
1736 | switch (TREE_CODE (expr)) | |
1737 | { | |
1738 | case INDIRECT_REF: | |
1739 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
1740 | if (t) | |
1741 | return t; | |
1742 | *walk_subtrees = 0; | |
1743 | ||
1744 | t = maybe_fold_stmt_indirect (expr, TREE_OPERAND (expr, 0), | |
1745 | integer_zero_node); | |
1746 | break; | |
1747 | ||
1748 | /* ??? Could handle ARRAY_REF here, as a variant of INDIRECT_REF. | |
1749 | We'd only want to bother decomposing an existing ARRAY_REF if | |
1750 | the base array is found to have another offset contained within. | |
1751 | Otherwise we'd be wasting time. */ | |
1752 | ||
1753 | case ADDR_EXPR: | |
1754 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
1755 | if (t) | |
1756 | return t; | |
1757 | *walk_subtrees = 0; | |
1758 | ||
1759 | /* Set TREE_INVARIANT properly so that the value is properly | |
1760 | considered constant, and so gets propagated as expected. */ | |
1761 | if (*changed_p) | |
1762 | recompute_tree_invarant_for_addr_expr (expr); | |
1763 | return NULL_TREE; | |
1764 | ||
1765 | case PLUS_EXPR: | |
1766 | case MINUS_EXPR: | |
1767 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
1768 | if (t) | |
1769 | return t; | |
1770 | t = walk_tree (&TREE_OPERAND (expr, 1), fold_stmt_r, data, NULL); | |
1771 | if (t) | |
1772 | return t; | |
1773 | *walk_subtrees = 0; | |
1774 | ||
1775 | t = maybe_fold_stmt_addition (expr); | |
1776 | break; | |
1777 | ||
1778 | case COMPONENT_REF: | |
1779 | t = walk_tree (&TREE_OPERAND (expr, 0), fold_stmt_r, data, NULL); | |
1780 | if (t) | |
1781 | return t; | |
1782 | *walk_subtrees = 0; | |
1783 | ||
fa27426e RH |
1784 | /* Make sure the FIELD_DECL is actually a field in the type on the lhs. |
1785 | We've already checked that the records are compatible, so we should | |
1786 | come up with a set of compatible fields. */ | |
1787 | { | |
1788 | tree expr_record = TREE_TYPE (TREE_OPERAND (expr, 0)); | |
1789 | tree expr_field = TREE_OPERAND (expr, 1); | |
1790 | ||
1791 | if (DECL_FIELD_CONTEXT (expr_field) != TYPE_MAIN_VARIANT (expr_record)) | |
1792 | { | |
1793 | expr_field = find_compatible_field (expr_record, expr_field); | |
1794 | TREE_OPERAND (expr, 1) = expr_field; | |
1795 | } | |
1796 | } | |
6de9cd9a DN |
1797 | break; |
1798 | ||
1799 | default: | |
1800 | return NULL_TREE; | |
1801 | } | |
1802 | ||
1803 | if (t) | |
1804 | { | |
1805 | *expr_p = t; | |
1806 | *changed_p = true; | |
1807 | } | |
1808 | ||
1809 | return NULL_TREE; | |
1810 | } | |
1811 | ||
6de9cd9a | 1812 | |
750628d8 DN |
1813 | /* Return the string length of ARG in LENGTH. If ARG is an SSA name variable, |
1814 | follow its use-def chains. If LENGTH is not NULL and its value is not | |
1815 | equal to the length we determine, or if we are unable to determine the | |
1816 | length, return false. VISITED is a bitmap of visited variables. */ | |
6de9cd9a | 1817 | |
06a9b53f | 1818 | static bool |
750628d8 | 1819 | get_strlen (tree arg, tree *length, bitmap visited) |
6de9cd9a | 1820 | { |
750628d8 DN |
1821 | tree var, def_stmt, val; |
1822 | ||
1823 | if (TREE_CODE (arg) != SSA_NAME) | |
06a9b53f | 1824 | { |
750628d8 DN |
1825 | val = c_strlen (arg, 1); |
1826 | if (!val) | |
06a9b53f | 1827 | return false; |
cd709752 | 1828 | |
750628d8 DN |
1829 | if (*length && simple_cst_equal (val, *length) != 1) |
1830 | return false; | |
6de9cd9a | 1831 | |
750628d8 DN |
1832 | *length = val; |
1833 | return true; | |
6de9cd9a | 1834 | } |
06a9b53f | 1835 | |
750628d8 DN |
1836 | /* If we were already here, break the infinite cycle. */ |
1837 | if (bitmap_bit_p (visited, SSA_NAME_VERSION (arg))) | |
1838 | return true; | |
1839 | bitmap_set_bit (visited, SSA_NAME_VERSION (arg)); | |
1840 | ||
1841 | var = arg; | |
1842 | def_stmt = SSA_NAME_DEF_STMT (var); | |
6de9cd9a | 1843 | |
750628d8 DN |
1844 | switch (TREE_CODE (def_stmt)) |
1845 | { | |
1846 | case MODIFY_EXPR: | |
1847 | { | |
1848 | tree len, rhs; | |
1849 | ||
1850 | /* The RHS of the statement defining VAR must either have a | |
1851 | constant length or come from another SSA_NAME with a constant | |
1852 | length. */ | |
1853 | rhs = TREE_OPERAND (def_stmt, 1); | |
1854 | STRIP_NOPS (rhs); | |
1855 | if (TREE_CODE (rhs) == SSA_NAME) | |
1856 | return get_strlen (rhs, length, visited); | |
6de9cd9a | 1857 | |
750628d8 DN |
1858 | /* See if the RHS is a constant length. */ |
1859 | len = c_strlen (rhs, 1); | |
1860 | if (len) | |
1861 | { | |
1862 | if (*length && simple_cst_equal (len, *length) != 1) | |
1863 | return false; | |
6de9cd9a | 1864 | |
750628d8 DN |
1865 | *length = len; |
1866 | return true; | |
1867 | } | |
6de9cd9a | 1868 | |
750628d8 DN |
1869 | break; |
1870 | } | |
6de9cd9a | 1871 | |
750628d8 DN |
1872 | case PHI_NODE: |
1873 | { | |
1874 | /* All the arguments of the PHI node must have the same constant | |
1875 | length. */ | |
1876 | int i; | |
6de9cd9a | 1877 | |
750628d8 DN |
1878 | for (i = 0; i < PHI_NUM_ARGS (def_stmt); i++) |
1879 | { | |
1880 | tree arg = PHI_ARG_DEF (def_stmt, i); | |
6de9cd9a | 1881 | |
750628d8 DN |
1882 | /* If this PHI has itself as an argument, we cannot |
1883 | determine the string length of this argument. However, | |
1884 | if we can find a constant string length for the other | |
1885 | PHI args then we can still be sure that this is a | |
1886 | constant string length. So be optimistic and just | |
1887 | continue with the next argument. */ | |
1888 | if (arg == PHI_RESULT (def_stmt)) | |
1889 | continue; | |
6de9cd9a | 1890 | |
750628d8 DN |
1891 | if (!get_strlen (arg, length, visited)) |
1892 | return false; | |
1893 | } | |
6de9cd9a | 1894 | |
750628d8 | 1895 | return true; |
173b818d | 1896 | } |
6de9cd9a | 1897 | |
750628d8 DN |
1898 | default: |
1899 | break; | |
6de9cd9a DN |
1900 | } |
1901 | ||
750628d8 DN |
1902 | |
1903 | return false; | |
6de9cd9a DN |
1904 | } |
1905 | ||
1906 | ||
1907 | /* Fold builtin call FN in statement STMT. If it cannot be folded into a | |
1908 | constant, return NULL_TREE. Otherwise, return its constant value. */ | |
1909 | ||
1910 | static tree | |
1911 | ccp_fold_builtin (tree stmt, tree fn) | |
1912 | { | |
1913 | tree result, strlen_val[2]; | |
a32e70c3 | 1914 | tree callee, arglist, a; |
6de9cd9a | 1915 | int strlen_arg, i; |
a32e70c3 RS |
1916 | bitmap visited; |
1917 | bool ignore; | |
6de9cd9a | 1918 | |
a32e70c3 | 1919 | ignore = TREE_CODE (stmt) != MODIFY_EXPR; |
6de9cd9a DN |
1920 | |
1921 | /* First try the generic builtin folder. If that succeeds, return the | |
1922 | result directly. */ | |
a32e70c3 | 1923 | result = fold_builtin (fn, ignore); |
6de9cd9a | 1924 | if (result) |
a32e70c3 RS |
1925 | { |
1926 | if (ignore) | |
1927 | STRIP_NOPS (result); | |
6de9cd9a | 1928 | return result; |
a32e70c3 RS |
1929 | } |
1930 | ||
1931 | /* Ignore MD builtins. */ | |
1932 | callee = get_callee_fndecl (fn); | |
1933 | if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD) | |
1934 | return NULL_TREE; | |
6de9cd9a DN |
1935 | |
1936 | /* If the builtin could not be folded, and it has no argument list, | |
1937 | we're done. */ | |
a32e70c3 | 1938 | arglist = TREE_OPERAND (fn, 1); |
6de9cd9a DN |
1939 | if (!arglist) |
1940 | return NULL_TREE; | |
1941 | ||
1942 | /* Limit the work only for builtins we know how to simplify. */ | |
1943 | switch (DECL_FUNCTION_CODE (callee)) | |
1944 | { | |
1945 | case BUILT_IN_STRLEN: | |
1946 | case BUILT_IN_FPUTS: | |
1947 | case BUILT_IN_FPUTS_UNLOCKED: | |
1948 | strlen_arg = 1; | |
1949 | break; | |
1950 | case BUILT_IN_STRCPY: | |
1951 | case BUILT_IN_STRNCPY: | |
1952 | strlen_arg = 2; | |
1953 | break; | |
1954 | default: | |
1955 | return NULL_TREE; | |
1956 | } | |
1957 | ||
1958 | /* Try to use the dataflow information gathered by the CCP process. */ | |
1959 | visited = BITMAP_XMALLOC (); | |
1960 | ||
1961 | memset (strlen_val, 0, sizeof (strlen_val)); | |
1962 | for (i = 0, a = arglist; | |
1963 | strlen_arg; | |
1964 | i++, strlen_arg >>= 1, a = TREE_CHAIN (a)) | |
1965 | if (strlen_arg & 1) | |
1966 | { | |
1967 | bitmap_clear (visited); | |
1968 | if (!get_strlen (TREE_VALUE (a), &strlen_val[i], visited)) | |
1969 | strlen_val[i] = NULL_TREE; | |
1970 | } | |
1971 | ||
1972 | BITMAP_XFREE (visited); | |
1973 | ||
a32e70c3 | 1974 | result = NULL_TREE; |
6de9cd9a DN |
1975 | switch (DECL_FUNCTION_CODE (callee)) |
1976 | { | |
1977 | case BUILT_IN_STRLEN: | |
a32e70c3 | 1978 | if (strlen_val[0]) |
6de9cd9a | 1979 | { |
a32e70c3 | 1980 | tree new = fold_convert (TREE_TYPE (fn), strlen_val[0]); |
6de9cd9a DN |
1981 | |
1982 | /* If the result is not a valid gimple value, or not a cast | |
1983 | of a valid gimple value, then we can not use the result. */ | |
1984 | if (is_gimple_val (new) | |
1985 | || (is_gimple_cast (new) | |
1986 | && is_gimple_val (TREE_OPERAND (new, 0)))) | |
1987 | return new; | |
6de9cd9a | 1988 | } |
a32e70c3 RS |
1989 | break; |
1990 | ||
6de9cd9a | 1991 | case BUILT_IN_STRCPY: |
a32e70c3 RS |
1992 | if (strlen_val[1] && is_gimple_val (strlen_val[1])) |
1993 | result = fold_builtin_strcpy (fn, strlen_val[1]); | |
1994 | break; | |
1995 | ||
6de9cd9a | 1996 | case BUILT_IN_STRNCPY: |
a32e70c3 RS |
1997 | if (strlen_val[1] && is_gimple_val (strlen_val[1])) |
1998 | result = fold_builtin_strncpy (fn, strlen_val[1]); | |
1999 | break; | |
2000 | ||
6de9cd9a | 2001 | case BUILT_IN_FPUTS: |
a32e70c3 RS |
2002 | result = fold_builtin_fputs (arglist, |
2003 | TREE_CODE (stmt) != MODIFY_EXPR, 0, | |
2004 | strlen_val[0]); | |
2005 | break; | |
2006 | ||
6de9cd9a | 2007 | case BUILT_IN_FPUTS_UNLOCKED: |
a32e70c3 RS |
2008 | result = fold_builtin_fputs (arglist, |
2009 | TREE_CODE (stmt) != MODIFY_EXPR, 1, | |
2010 | strlen_val[0]); | |
2011 | break; | |
6de9cd9a DN |
2012 | |
2013 | default: | |
1e128c5f | 2014 | gcc_unreachable (); |
6de9cd9a DN |
2015 | } |
2016 | ||
a32e70c3 | 2017 | if (result && ignore) |
9675412f | 2018 | result = fold_ignored_result (result); |
a32e70c3 | 2019 | return result; |
6de9cd9a DN |
2020 | } |
2021 | ||
2022 | ||
750628d8 DN |
2023 | /* Fold the statement pointed by STMT_P. In some cases, this function may |
2024 | replace the whole statement with a new one. Returns true iff folding | |
2025 | makes any changes. */ | |
6de9cd9a | 2026 | |
750628d8 DN |
2027 | bool |
2028 | fold_stmt (tree *stmt_p) | |
6de9cd9a | 2029 | { |
750628d8 DN |
2030 | tree rhs, result, stmt; |
2031 | bool changed = false; | |
6de9cd9a | 2032 | |
750628d8 | 2033 | stmt = *stmt_p; |
6de9cd9a | 2034 | |
750628d8 DN |
2035 | /* If we replaced constants and the statement makes pointer dereferences, |
2036 | then we may need to fold instances of *&VAR into VAR, etc. */ | |
2037 | if (walk_tree (stmt_p, fold_stmt_r, &changed, NULL)) | |
2038 | { | |
2039 | *stmt_p | |
2040 | = build_function_call_expr (implicit_built_in_decls[BUILT_IN_TRAP], | |
2041 | NULL); | |
6de9cd9a DN |
2042 | return true; |
2043 | } | |
2044 | ||
750628d8 DN |
2045 | rhs = get_rhs (stmt); |
2046 | if (!rhs) | |
2047 | return changed; | |
2048 | result = NULL_TREE; | |
6de9cd9a | 2049 | |
750628d8 | 2050 | if (TREE_CODE (rhs) == CALL_EXPR) |
6de9cd9a | 2051 | { |
750628d8 | 2052 | tree callee; |
6de9cd9a | 2053 | |
750628d8 DN |
2054 | /* Check for builtins that CCP can handle using information not |
2055 | available in the generic fold routines. */ | |
2056 | callee = get_callee_fndecl (rhs); | |
2057 | if (callee && DECL_BUILT_IN (callee)) | |
2058 | result = ccp_fold_builtin (stmt, rhs); | |
2059 | else | |
6de9cd9a | 2060 | { |
750628d8 DN |
2061 | /* Check for resolvable OBJ_TYPE_REF. The only sorts we can resolve |
2062 | here are when we've propagated the address of a decl into the | |
2063 | object slot. */ | |
2064 | /* ??? Should perhaps do this in fold proper. However, doing it | |
2065 | there requires that we create a new CALL_EXPR, and that requires | |
2066 | copying EH region info to the new node. Easier to just do it | |
2067 | here where we can just smash the call operand. */ | |
2068 | callee = TREE_OPERAND (rhs, 0); | |
2069 | if (TREE_CODE (callee) == OBJ_TYPE_REF | |
2070 | && lang_hooks.fold_obj_type_ref | |
2071 | && TREE_CODE (OBJ_TYPE_REF_OBJECT (callee)) == ADDR_EXPR | |
6615c446 JO |
2072 | && DECL_P (TREE_OPERAND |
2073 | (OBJ_TYPE_REF_OBJECT (callee), 0))) | |
6de9cd9a | 2074 | { |
750628d8 | 2075 | tree t; |
6de9cd9a | 2076 | |
750628d8 DN |
2077 | /* ??? Caution: Broken ADDR_EXPR semantics means that |
2078 | looking at the type of the operand of the addr_expr | |
2079 | can yield an array type. See silly exception in | |
2080 | check_pointer_types_r. */ | |
6de9cd9a | 2081 | |
750628d8 DN |
2082 | t = TREE_TYPE (TREE_TYPE (OBJ_TYPE_REF_OBJECT (callee))); |
2083 | t = lang_hooks.fold_obj_type_ref (callee, t); | |
2084 | if (t) | |
2085 | { | |
2086 | TREE_OPERAND (rhs, 0) = t; | |
2087 | changed = true; | |
2088 | } | |
6de9cd9a | 2089 | } |
6de9cd9a | 2090 | } |
6de9cd9a DN |
2091 | } |
2092 | ||
750628d8 DN |
2093 | /* If we couldn't fold the RHS, hand over to the generic fold routines. */ |
2094 | if (result == NULL_TREE) | |
2095 | result = fold (rhs); | |
6de9cd9a | 2096 | |
750628d8 DN |
2097 | /* Strip away useless type conversions. Both the NON_LVALUE_EXPR that |
2098 | may have been added by fold, and "useless" type conversions that might | |
2099 | now be apparent due to propagation. */ | |
2100 | STRIP_USELESS_TYPE_CONVERSION (result); | |
2101 | ||
2102 | if (result != rhs) | |
2103 | changed |= set_rhs (stmt_p, result); | |
2104 | ||
2105 | return changed; | |
6de9cd9a DN |
2106 | } |
2107 | ||
2108 | \f | |
b28b1600 JJ |
2109 | /* Convert EXPR into a GIMPLE value suitable for substitution on the |
2110 | RHS of an assignment. Insert the necessary statements before | |
2111 | iterator *SI_P. */ | |
2112 | ||
2113 | static tree | |
2114 | convert_to_gimple_builtin (block_stmt_iterator *si_p, tree expr) | |
2115 | { | |
2116 | tree_stmt_iterator ti; | |
2117 | tree stmt = bsi_stmt (*si_p); | |
2118 | tree tmp, stmts = NULL; | |
2119 | ||
2120 | push_gimplify_context (); | |
2121 | tmp = get_initialized_tmp_var (expr, &stmts, NULL); | |
2122 | pop_gimplify_context (NULL); | |
2123 | ||
2124 | /* The replacement can expose previously unreferenced variables. */ | |
2125 | for (ti = tsi_start (stmts); !tsi_end_p (ti); tsi_next (&ti)) | |
2126 | { | |
2127 | find_new_referenced_vars (tsi_stmt_ptr (ti)); | |
2128 | mark_new_vars_to_rename (tsi_stmt (ti), vars_to_rename); | |
2129 | } | |
2130 | ||
2131 | if (EXPR_HAS_LOCATION (stmt)) | |
2132 | annotate_all_with_locus (&stmts, EXPR_LOCATION (stmt)); | |
2133 | ||
2134 | bsi_insert_before (si_p, stmts, BSI_SAME_STMT); | |
2135 | ||
2136 | return tmp; | |
2137 | } | |
2138 | ||
2139 | ||
6de9cd9a DN |
2140 | /* A simple pass that attempts to fold all builtin functions. This pass |
2141 | is run after we've propagated as many constants as we can. */ | |
2142 | ||
2143 | static void | |
2144 | execute_fold_all_builtins (void) | |
2145 | { | |
2146 | basic_block bb; | |
2147 | FOR_EACH_BB (bb) | |
2148 | { | |
2149 | block_stmt_iterator i; | |
2150 | for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i)) | |
2151 | { | |
2152 | tree *stmtp = bsi_stmt_ptr (i); | |
2153 | tree call = get_rhs (*stmtp); | |
2154 | tree callee, result; | |
2155 | ||
2156 | if (!call || TREE_CODE (call) != CALL_EXPR) | |
2157 | continue; | |
2158 | callee = get_callee_fndecl (call); | |
2159 | if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL) | |
2160 | continue; | |
2161 | ||
2162 | result = ccp_fold_builtin (*stmtp, call); | |
2163 | if (!result) | |
2164 | switch (DECL_FUNCTION_CODE (callee)) | |
2165 | { | |
2166 | case BUILT_IN_CONSTANT_P: | |
2167 | /* Resolve __builtin_constant_p. If it hasn't been | |
2168 | folded to integer_one_node by now, it's fairly | |
2169 | certain that the value simply isn't constant. */ | |
2170 | result = integer_zero_node; | |
2171 | break; | |
2172 | ||
2173 | default: | |
2174 | continue; | |
2175 | } | |
2176 | ||
2177 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2178 | { | |
2179 | fprintf (dump_file, "Simplified\n "); | |
2180 | print_generic_stmt (dump_file, *stmtp, dump_flags); | |
2181 | } | |
2182 | ||
b28b1600 JJ |
2183 | if (!set_rhs (stmtp, result)) |
2184 | { | |
2185 | result = convert_to_gimple_builtin (&i, result); | |
2186 | if (result && !set_rhs (stmtp, result)) | |
2187 | abort (); | |
2188 | } | |
2189 | modify_stmt (*stmtp); | |
6de9cd9a DN |
2190 | |
2191 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2192 | { | |
2193 | fprintf (dump_file, "to\n "); | |
2194 | print_generic_stmt (dump_file, *stmtp, dump_flags); | |
2195 | fprintf (dump_file, "\n"); | |
2196 | } | |
2197 | } | |
2198 | } | |
2199 | } | |
2200 | ||
750628d8 | 2201 | |
6de9cd9a DN |
2202 | struct tree_opt_pass pass_fold_builtins = |
2203 | { | |
2204 | "fab", /* name */ | |
2205 | NULL, /* gate */ | |
2206 | execute_fold_all_builtins, /* execute */ | |
2207 | NULL, /* sub */ | |
2208 | NULL, /* next */ | |
2209 | 0, /* static_pass_number */ | |
2210 | 0, /* tv_id */ | |
c1b763fa | 2211 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ |
6de9cd9a DN |
2212 | 0, /* properties_provided */ |
2213 | 0, /* properties_destroyed */ | |
2214 | 0, /* todo_flags_start */ | |
b28b1600 JJ |
2215 | TODO_dump_func |
2216 | | TODO_verify_ssa | |
2217 | | TODO_rename_vars, /* todo_flags_finish */ | |
9f8628ba | 2218 | 0 /* letter */ |
6de9cd9a | 2219 | }; |