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f7d118a9 | 1 | /* Callgraph based analysis of static variables. |
26dbec0a | 2 | Copyright (C) 2004, 2005, 2007, 2008, 2009 Free Software Foundation, Inc. |
f7d118a9 | 3 | Contributed by Kenneth Zadeck <zadeck@naturalbridge.com> |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
8c4c00c1 | 9 | Software Foundation; either version 3, or (at your option) any later |
f7d118a9 | 10 | version. |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
8c4c00c1 | 18 | along with GCC; see the file COPYING3. If not see |
19 | <http://www.gnu.org/licenses/>. */ | |
f7d118a9 | 20 | |
f0b5f617 | 21 | /* This file marks functions as being either const (TREE_READONLY) or |
22 | pure (DECL_PURE_P). It can also set a variant of these that | |
23 | are allowed to loop indefinitely (DECL_LOOPING_CONST_PURE_P). | |
f7d118a9 | 24 | |
25 | This must be run after inlining decisions have been made since | |
26 | otherwise, the local sets will not contain information that is | |
27 | consistent with post inlined state. The global sets are not prone | |
28 | to this problem since they are by definition transitive. */ | |
29 | ||
30 | /* The code in this module is called by the ipa pass manager. It | |
31 | should be one of the later passes since it's information is used by | |
32 | the rest of the compilation. */ | |
33 | ||
34 | #include "config.h" | |
35 | #include "system.h" | |
36 | #include "coretypes.h" | |
37 | #include "tm.h" | |
38 | #include "tree.h" | |
39 | #include "tree-flow.h" | |
40 | #include "tree-inline.h" | |
41 | #include "tree-pass.h" | |
42 | #include "langhooks.h" | |
43 | #include "pointer-set.h" | |
44 | #include "ggc.h" | |
45 | #include "ipa-utils.h" | |
75a70cf9 | 46 | #include "gimple.h" |
f7d118a9 | 47 | #include "cgraph.h" |
48 | #include "output.h" | |
49 | #include "flags.h" | |
50 | #include "timevar.h" | |
51 | #include "diagnostic.h" | |
52 | #include "langhooks.h" | |
959fce68 | 53 | #include "target.h" |
c9263b6a | 54 | #include "cfgloop.h" |
55 | #include "tree-scalar-evolution.h" | |
f7d118a9 | 56 | |
57 | static struct pointer_set_t *visited_nodes; | |
58 | ||
59 | /* Lattice values for const and pure functions. Everything starts out | |
60 | being const, then may drop to pure and then neither depending on | |
61 | what is found. */ | |
62 | enum pure_const_state_e | |
63 | { | |
64 | IPA_CONST, | |
65 | IPA_PURE, | |
66 | IPA_NEITHER | |
67 | }; | |
68 | ||
cb886925 | 69 | /* Holder for the const_state. There is one of these per function |
70 | decl. */ | |
f7d118a9 | 71 | struct funct_state_d |
72 | { | |
cb886925 | 73 | /* See above. */ |
f7d118a9 | 74 | enum pure_const_state_e pure_const_state; |
b5cebd44 | 75 | /* What user set here; we can be always sure about this. */ |
df9b545b | 76 | enum pure_const_state_e state_previously_known; |
77 | bool looping_previously_known; | |
cb886925 | 78 | |
79 | /* True if the function could possibly infinite loop. There are a | |
80 | lot of ways that this could be determined. We are pretty | |
81 | conservative here. While it is possible to cse pure and const | |
82 | calls, it is not legal to have dce get rid of the call if there | |
83 | is a possibility that the call could infinite loop since this is | |
84 | a behavioral change. */ | |
9c2a0c05 | 85 | bool looping; |
cb886925 | 86 | |
b5cebd44 | 87 | bool can_throw; |
f7d118a9 | 88 | }; |
89 | ||
90 | typedef struct funct_state_d * funct_state; | |
91 | ||
cb886925 | 92 | /* The storage of the funct_state is abstracted because there is the |
93 | possibility that it may be desirable to move this to the cgraph | |
94 | local info. */ | |
95 | ||
96 | /* Array, indexed by cgraph node uid, of function states. */ | |
97 | ||
86844d6c | 98 | DEF_VEC_P (funct_state); |
99 | DEF_VEC_ALLOC_P (funct_state, heap); | |
100 | static VEC (funct_state, heap) *funct_state_vec; | |
cb886925 | 101 | |
50828ed8 | 102 | /* Holders of ipa cgraph hooks: */ |
103 | static struct cgraph_node_hook_list *function_insertion_hook_holder; | |
86844d6c | 104 | static struct cgraph_2node_hook_list *node_duplication_hook_holder; |
105 | static struct cgraph_node_hook_list *node_removal_hook_holder; | |
cb886925 | 106 | |
107 | /* Init the function state. */ | |
108 | ||
109 | static void | |
110 | finish_state (void) | |
111 | { | |
112 | free (funct_state_vec); | |
113 | } | |
114 | ||
115 | ||
f7d118a9 | 116 | /* Return the function state from NODE. */ |
117 | ||
118 | static inline funct_state | |
119 | get_function_state (struct cgraph_node *node) | |
120 | { | |
86844d6c | 121 | if (!funct_state_vec |
122 | || VEC_length (funct_state, funct_state_vec) <= (unsigned int)node->uid) | |
123 | return NULL; | |
124 | return VEC_index (funct_state, funct_state_vec, node->uid); | |
cb886925 | 125 | } |
126 | ||
127 | /* Set the function state S for NODE. */ | |
128 | ||
129 | static inline void | |
130 | set_function_state (struct cgraph_node *node, funct_state s) | |
131 | { | |
86844d6c | 132 | if (!funct_state_vec |
133 | || VEC_length (funct_state, funct_state_vec) <= (unsigned int)node->uid) | |
134 | VEC_safe_grow_cleared (funct_state, heap, funct_state_vec, node->uid + 1); | |
135 | VEC_replace (funct_state, funct_state_vec, node->uid, s); | |
f7d118a9 | 136 | } |
137 | ||
f0b5f617 | 138 | /* Check to see if the use (or definition when CHECKING_WRITE is true) |
f7d118a9 | 139 | variable T is legal in a function that is either pure or const. */ |
140 | ||
141 | static inline void | |
142 | check_decl (funct_state local, | |
143 | tree t, bool checking_write) | |
144 | { | |
f7d118a9 | 145 | /* Do not want to do anything with volatile except mark any |
146 | function that uses one to be not const or pure. */ | |
147 | if (TREE_THIS_VOLATILE (t)) | |
148 | { | |
149 | local->pure_const_state = IPA_NEITHER; | |
b5cebd44 | 150 | if (dump_file) |
151 | fprintf (dump_file, " Volatile operand is not const/pure"); | |
f7d118a9 | 152 | return; |
153 | } | |
154 | ||
155 | /* Do not care about a local automatic that is not static. */ | |
156 | if (!TREE_STATIC (t) && !DECL_EXTERNAL (t)) | |
157 | return; | |
158 | ||
b5cebd44 | 159 | /* If the variable has the "used" attribute, treat it as if it had a |
160 | been touched by the devil. */ | |
161 | if (lookup_attribute ("used", DECL_ATTRIBUTES (t))) | |
162 | { | |
163 | local->pure_const_state = IPA_NEITHER; | |
164 | if (dump_file) | |
165 | fprintf (dump_file, " Used static/global variable is not const/pure\n"); | |
166 | return; | |
167 | } | |
168 | ||
f7d118a9 | 169 | /* Since we have dealt with the locals and params cases above, if we |
170 | are CHECKING_WRITE, this cannot be a pure or constant | |
171 | function. */ | |
172 | if (checking_write) | |
bc17fd99 | 173 | { |
174 | local->pure_const_state = IPA_NEITHER; | |
b5cebd44 | 175 | if (dump_file) |
176 | fprintf (dump_file, " static/global memory write is not const/pure\n"); | |
bc17fd99 | 177 | return; |
178 | } | |
f7d118a9 | 179 | |
180 | if (DECL_EXTERNAL (t) || TREE_PUBLIC (t)) | |
181 | { | |
b5cebd44 | 182 | /* Readonly reads are safe. */ |
183 | if (TREE_READONLY (t) && !TYPE_NEEDS_CONSTRUCTING (TREE_TYPE (t))) | |
184 | return; /* Read of a constant, do not change the function state. */ | |
f7d118a9 | 185 | else |
186 | { | |
b5cebd44 | 187 | if (dump_file) |
188 | fprintf (dump_file, " global memory read is not const\n"); | |
f7d118a9 | 189 | /* Just a regular read. */ |
190 | if (local->pure_const_state == IPA_CONST) | |
191 | local->pure_const_state = IPA_PURE; | |
192 | } | |
193 | } | |
b5cebd44 | 194 | else |
195 | { | |
196 | /* Compilation level statics can be read if they are readonly | |
197 | variables. */ | |
198 | if (TREE_READONLY (t)) | |
199 | return; | |
200 | ||
201 | if (dump_file) | |
202 | fprintf (dump_file, " static memory read is not const\n"); | |
203 | /* Just a regular read. */ | |
204 | if (local->pure_const_state == IPA_CONST) | |
205 | local->pure_const_state = IPA_PURE; | |
206 | } | |
f7d118a9 | 207 | } |
208 | ||
f7d118a9 | 209 | |
b5cebd44 | 210 | /* Check to see if the use (or definition when CHECKING_WRITE is true) |
211 | variable T is legal in a function that is either pure or const. */ | |
f7d118a9 | 212 | |
b5cebd44 | 213 | static inline void |
5ed0b345 | 214 | check_op (funct_state local, tree t, bool checking_write) |
f7d118a9 | 215 | { |
3ae61172 | 216 | t = get_base_address (t); |
217 | if (t && TREE_THIS_VOLATILE (t)) | |
f7d118a9 | 218 | { |
5ed0b345 | 219 | local->pure_const_state = IPA_NEITHER; |
220 | if (dump_file) | |
221 | fprintf (dump_file, " Volatile indirect ref is not const/pure\n"); | |
222 | return; | |
223 | } | |
3ae61172 | 224 | else if (t |
225 | && INDIRECT_REF_P (t) | |
226 | && TREE_CODE (TREE_OPERAND (t, 0)) == SSA_NAME | |
227 | && !ptr_deref_may_alias_global_p (TREE_OPERAND (t, 0))) | |
228 | { | |
229 | if (dump_file) | |
230 | fprintf (dump_file, " Indirect ref to local memory is OK\n"); | |
231 | return; | |
232 | } | |
5ed0b345 | 233 | else if (checking_write) |
234 | { | |
235 | local->pure_const_state = IPA_NEITHER; | |
236 | if (dump_file) | |
237 | fprintf (dump_file, " Indirect ref write is not const/pure\n"); | |
238 | return; | |
239 | } | |
240 | else | |
241 | { | |
242 | if (dump_file) | |
243 | fprintf (dump_file, " Indirect ref read is not const\n"); | |
244 | if (local->pure_const_state == IPA_CONST) | |
245 | local->pure_const_state = IPA_PURE; | |
f7d118a9 | 246 | } |
247 | } | |
248 | ||
f7d118a9 | 249 | /* Check the parameters of a function call to CALL_EXPR to see if |
250 | there are any references in the parameters that are not allowed for | |
251 | pure or const functions. Also check to see if this is either an | |
252 | indirect call, a call outside the compilation unit, or has special | |
253 | attributes that may also effect the purity. The CALL_EXPR node for | |
254 | the entire call expression. */ | |
255 | ||
256 | static void | |
b5cebd44 | 257 | check_call (funct_state local, gimple call, bool ipa) |
f7d118a9 | 258 | { |
75a70cf9 | 259 | int flags = gimple_call_flags (call); |
b5cebd44 | 260 | tree callee_t = gimple_call_fndecl (call); |
f7d118a9 | 261 | struct cgraph_node* callee; |
262 | enum availability avail = AVAIL_NOT_AVAILABLE; | |
b5cebd44 | 263 | bool possibly_throws = stmt_could_throw_p (call); |
264 | bool possibly_throws_externally = (possibly_throws | |
265 | && stmt_can_throw_external (call)); | |
f7d118a9 | 266 | |
b5cebd44 | 267 | if (possibly_throws) |
268 | { | |
269 | unsigned int i; | |
270 | for (i = 0; i < gimple_num_ops (call); i++) | |
271 | if (gimple_op (call, i) | |
272 | && tree_could_throw_p (gimple_op (call, i))) | |
273 | { | |
274 | if (possibly_throws && flag_non_call_exceptions) | |
275 | { | |
276 | if (dump_file) | |
277 | fprintf (dump_file, " operand can throw; looping\n"); | |
278 | local->looping = true; | |
279 | } | |
280 | if (possibly_throws_externally) | |
281 | { | |
282 | if (dump_file) | |
283 | fprintf (dump_file, " operand can throw externally\n"); | |
284 | local->can_throw = true; | |
285 | } | |
286 | } | |
287 | } | |
f7d118a9 | 288 | |
289 | /* The const and pure flags are set by a variety of places in the | |
290 | compiler (including here). If someone has already set the flags | |
291 | for the callee, (such as for some of the builtins) we will use | |
292 | them, otherwise we will compute our own information. | |
293 | ||
294 | Const and pure functions have less clobber effects than other | |
295 | functions so we process these first. Otherwise if it is a call | |
296 | outside the compilation unit or an indirect call we punt. This | |
297 | leaves local calls which will be processed by following the call | |
298 | graph. */ | |
299 | if (callee_t) | |
300 | { | |
301 | callee = cgraph_node(callee_t); | |
302 | avail = cgraph_function_body_availability (callee); | |
303 | ||
304 | /* When bad things happen to bad functions, they cannot be const | |
305 | or pure. */ | |
306 | if (setjmp_call_p (callee_t)) | |
9c2a0c05 | 307 | { |
b5cebd44 | 308 | if (dump_file) |
309 | fprintf (dump_file, " setjmp is not const/pure\n"); | |
310 | local->looping = true; | |
9c2a0c05 | 311 | local->pure_const_state = IPA_NEITHER; |
9c2a0c05 | 312 | } |
f7d118a9 | 313 | |
314 | if (DECL_BUILT_IN_CLASS (callee_t) == BUILT_IN_NORMAL) | |
315 | switch (DECL_FUNCTION_CODE (callee_t)) | |
316 | { | |
317 | case BUILT_IN_LONGJMP: | |
318 | case BUILT_IN_NONLOCAL_GOTO: | |
b5cebd44 | 319 | if (dump_file) |
320 | fprintf (dump_file, " longjmp and nonlocal goto is not const/pure\n"); | |
f7d118a9 | 321 | local->pure_const_state = IPA_NEITHER; |
b5cebd44 | 322 | local->looping = true; |
f7d118a9 | 323 | break; |
324 | default: | |
325 | break; | |
326 | } | |
327 | } | |
328 | ||
b5cebd44 | 329 | /* When not in IPA mode, we can still handle self recursion. */ |
330 | if (!ipa && callee_t == current_function_decl) | |
331 | local->looping = true; | |
f7d118a9 | 332 | /* The callee is either unknown (indirect call) or there is just no |
333 | scannable code for it (external call) . We look to see if there | |
334 | are any bits available for the callee (such as by declaration or | |
335 | because it is builtin) and process solely on the basis of those | |
336 | bits. */ | |
b5cebd44 | 337 | else if (avail <= AVAIL_OVERWRITABLE || !ipa) |
f7d118a9 | 338 | { |
b5cebd44 | 339 | if (possibly_throws && flag_non_call_exceptions) |
340 | { | |
341 | if (dump_file) | |
342 | fprintf (dump_file, " can throw; looping\n"); | |
343 | local->looping = true; | |
344 | } | |
345 | if (possibly_throws_externally) | |
346 | { | |
347 | if (dump_file) | |
348 | { | |
e38def9c | 349 | fprintf (dump_file, " can throw externally to lp %i\n", |
350 | lookup_stmt_eh_lp (call)); | |
b5cebd44 | 351 | if (callee_t) |
352 | fprintf (dump_file, " callee:%s\n", | |
353 | IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (callee_t))); | |
354 | } | |
355 | local->can_throw = true; | |
356 | } | |
357 | if (flags & ECF_CONST) | |
f7d118a9 | 358 | { |
b5cebd44 | 359 | if (callee_t && DECL_LOOPING_CONST_OR_PURE_P (callee_t)) |
360 | local->looping = true; | |
361 | } | |
362 | else if (flags & ECF_PURE) | |
363 | { | |
364 | if (callee_t && DECL_LOOPING_CONST_OR_PURE_P (callee_t)) | |
365 | local->looping = true; | |
366 | if (dump_file) | |
367 | fprintf (dump_file, " pure function call in not const\n"); | |
f7d118a9 | 368 | if (local->pure_const_state == IPA_CONST) |
369 | local->pure_const_state = IPA_PURE; | |
370 | } | |
371 | else | |
f7d118a9 | 372 | { |
b5cebd44 | 373 | if (dump_file) |
374 | fprintf (dump_file, " uknown function call is not const/pure\n"); | |
375 | local->pure_const_state = IPA_NEITHER; | |
376 | local->looping = true; | |
f7d118a9 | 377 | } |
378 | } | |
b5cebd44 | 379 | /* Direct functions calls are handled by IPA propagation. */ |
f7d118a9 | 380 | } |
381 | ||
5ed0b345 | 382 | /* Wrapper around check_decl for loads. */ |
383 | ||
384 | static bool | |
385 | check_load (gimple stmt ATTRIBUTE_UNUSED, tree op, void *data) | |
386 | { | |
387 | if (DECL_P (op)) | |
388 | check_decl ((funct_state)data, op, false); | |
389 | else | |
390 | check_op ((funct_state)data, op, false); | |
391 | return false; | |
392 | } | |
393 | ||
394 | /* Wrapper around check_decl for stores. */ | |
395 | ||
396 | static bool | |
397 | check_store (gimple stmt ATTRIBUTE_UNUSED, tree op, void *data) | |
398 | { | |
399 | if (DECL_P (op)) | |
400 | check_decl ((funct_state)data, op, true); | |
401 | else | |
402 | check_op ((funct_state)data, op, true); | |
403 | return false; | |
404 | } | |
405 | ||
dd277d48 | 406 | /* Look into pointer pointed to by GSIP and figure out what interesting side |
407 | effects it has. */ | |
b5cebd44 | 408 | static void |
409 | check_stmt (gimple_stmt_iterator *gsip, funct_state local, bool ipa) | |
f7d118a9 | 410 | { |
b5cebd44 | 411 | gimple stmt = gsi_stmt (*gsip); |
412 | unsigned int i = 0; | |
f7d118a9 | 413 | |
9845d120 | 414 | if (is_gimple_debug (stmt)) |
415 | return; | |
416 | ||
b5cebd44 | 417 | if (dump_file) |
f7d118a9 | 418 | { |
b5cebd44 | 419 | fprintf (dump_file, " scanning: "); |
420 | print_gimple_stmt (dump_file, stmt, 0, 0); | |
421 | } | |
dd277d48 | 422 | |
5ed0b345 | 423 | /* Look for loads and stores. */ |
424 | walk_stmt_load_store_ops (stmt, local, check_load, check_store); | |
b5cebd44 | 425 | |
426 | if (gimple_code (stmt) != GIMPLE_CALL | |
427 | && stmt_could_throw_p (stmt)) | |
428 | { | |
429 | if (flag_non_call_exceptions) | |
430 | { | |
431 | if (dump_file) | |
432 | fprintf (dump_file, " can throw; looping"); | |
433 | local->looping = true; | |
434 | } | |
435 | if (stmt_can_throw_external (stmt)) | |
436 | { | |
437 | if (dump_file) | |
438 | fprintf (dump_file, " can throw externally"); | |
439 | local->can_throw = true; | |
440 | } | |
75a70cf9 | 441 | } |
75a70cf9 | 442 | switch (gimple_code (stmt)) |
443 | { | |
b5cebd44 | 444 | case GIMPLE_CALL: |
b5cebd44 | 445 | check_call (local, stmt, ipa); |
f7d118a9 | 446 | break; |
75a70cf9 | 447 | case GIMPLE_LABEL: |
448 | if (DECL_NONLOCAL (gimple_label_label (stmt))) | |
f7d118a9 | 449 | /* Target of long jump. */ |
9c2a0c05 | 450 | { |
b5cebd44 | 451 | if (dump_file) |
452 | fprintf (dump_file, " nonlocal label is not const/pure"); | |
9c2a0c05 | 453 | local->pure_const_state = IPA_NEITHER; |
9c2a0c05 | 454 | } |
f7d118a9 | 455 | break; |
75a70cf9 | 456 | case GIMPLE_ASM: |
b5cebd44 | 457 | for (i = 0; i < gimple_asm_nclobbers (stmt); i++) |
458 | { | |
459 | tree op = gimple_asm_clobber_op (stmt, i); | |
460 | if (simple_cst_equal(TREE_VALUE (op), memory_identifier_string) == 1) | |
461 | { | |
462 | if (dump_file) | |
463 | fprintf (dump_file, " memory asm clobber is not const/pure"); | |
464 | /* Abandon all hope, ye who enter here. */ | |
465 | local->pure_const_state = IPA_NEITHER; | |
466 | } | |
467 | } | |
468 | if (gimple_asm_volatile_p (stmt)) | |
469 | { | |
470 | if (dump_file) | |
471 | fprintf (dump_file, " volatile is not const/pure"); | |
472 | /* Abandon all hope, ye who enter here. */ | |
473 | local->pure_const_state = IPA_NEITHER; | |
474 | local->looping = true; | |
475 | } | |
476 | return; | |
f7d118a9 | 477 | default: |
478 | break; | |
479 | } | |
f7d118a9 | 480 | } |
481 | ||
cb886925 | 482 | |
f7d118a9 | 483 | /* This is the main routine for finding the reference patterns for |
484 | global variables within a function FN. */ | |
485 | ||
b5cebd44 | 486 | static funct_state |
487 | analyze_function (struct cgraph_node *fn, bool ipa) | |
f7d118a9 | 488 | { |
f7d118a9 | 489 | tree decl = fn->decl; |
b5cebd44 | 490 | tree old_decl = current_function_decl; |
491 | funct_state l; | |
492 | basic_block this_block; | |
f7d118a9 | 493 | |
b5cebd44 | 494 | if (cgraph_function_body_availability (fn) <= AVAIL_OVERWRITABLE) |
f7d118a9 | 495 | { |
b5cebd44 | 496 | if (dump_file) |
497 | fprintf (dump_file, "Function is not available or overwrittable; not analyzing.\n"); | |
498 | return NULL; | |
f7d118a9 | 499 | } |
500 | ||
b5cebd44 | 501 | l = XCNEW (struct funct_state_d); |
502 | l->pure_const_state = IPA_CONST; | |
df9b545b | 503 | l->state_previously_known = IPA_NEITHER; |
504 | l->looping_previously_known = true; | |
b5cebd44 | 505 | l->looping = false; |
506 | l->can_throw = false; | |
f7d118a9 | 507 | |
508 | if (dump_file) | |
509 | { | |
b5cebd44 | 510 | fprintf (dump_file, "\n\n local analysis of %s\n ", |
511 | cgraph_node_name (fn)); | |
f7d118a9 | 512 | } |
513 | ||
b5cebd44 | 514 | push_cfun (DECL_STRUCT_FUNCTION (decl)); |
515 | current_function_decl = decl; | |
516 | ||
517 | FOR_EACH_BB (this_block) | |
f7d118a9 | 518 | { |
b5cebd44 | 519 | gimple_stmt_iterator gsi; |
520 | struct walk_stmt_info wi; | |
f7d118a9 | 521 | |
b5cebd44 | 522 | memset (&wi, 0, sizeof(wi)); |
523 | for (gsi = gsi_start_bb (this_block); | |
524 | !gsi_end_p (gsi); | |
525 | gsi_next (&gsi)) | |
f7d118a9 | 526 | { |
b5cebd44 | 527 | check_stmt (&gsi, l, ipa); |
528 | if (l->pure_const_state == IPA_NEITHER && l->looping && l->can_throw) | |
529 | goto end; | |
f7d118a9 | 530 | } |
531 | } | |
dcccac3e | 532 | |
533 | end: | |
b5cebd44 | 534 | if (l->pure_const_state != IPA_NEITHER) |
535 | { | |
536 | /* Const functions cannot have back edges (an | |
537 | indication of possible infinite loop side | |
538 | effect. */ | |
539 | if (mark_dfs_back_edges ()) | |
c9263b6a | 540 | { |
b1887855 | 541 | /* Preheaders are needed for SCEV to work. |
542 | Simple lateches and recorded exits improve chances that loop will | |
543 | proved to be finite in testcases such as in loop-15.c and loop-24.c */ | |
544 | loop_optimizer_init (LOOPS_NORMAL | |
545 | | LOOPS_HAVE_RECORDED_EXITS); | |
c9263b6a | 546 | if (dump_file && (dump_flags & TDF_DETAILS)) |
547 | flow_loops_dump (dump_file, NULL, 0); | |
548 | if (mark_irreducible_loops ()) | |
549 | { | |
550 | if (dump_file) | |
551 | fprintf (dump_file, " has irreducible loops\n"); | |
552 | l->looping = true; | |
553 | } | |
554 | else | |
555 | { | |
556 | loop_iterator li; | |
557 | struct loop *loop; | |
558 | scev_initialize (); | |
559 | FOR_EACH_LOOP (li, loop, 0) | |
560 | if (!finite_loop_p (loop)) | |
561 | { | |
562 | if (dump_file) | |
563 | fprintf (dump_file, " can not prove finiteness of loop %i\n", loop->num); | |
564 | l->looping =true; | |
565 | break; | |
566 | } | |
567 | scev_finalize (); | |
568 | } | |
569 | loop_optimizer_finalize (); | |
570 | } | |
b5cebd44 | 571 | } |
572 | ||
573 | if (TREE_READONLY (decl)) | |
574 | { | |
575 | l->pure_const_state = IPA_CONST; | |
df9b545b | 576 | l->state_previously_known = IPA_CONST; |
b5cebd44 | 577 | if (!DECL_LOOPING_CONST_OR_PURE_P (decl)) |
df9b545b | 578 | l->looping = false, l->looping_previously_known = false; |
b5cebd44 | 579 | } |
580 | if (DECL_PURE_P (decl)) | |
581 | { | |
582 | if (l->pure_const_state != IPA_CONST) | |
583 | l->pure_const_state = IPA_PURE; | |
df9b545b | 584 | l->state_previously_known = IPA_PURE; |
b5cebd44 | 585 | if (!DECL_LOOPING_CONST_OR_PURE_P (decl)) |
df9b545b | 586 | l->looping = false, l->looping_previously_known = false; |
b5cebd44 | 587 | } |
588 | if (TREE_NOTHROW (decl)) | |
589 | l->can_throw = false; | |
590 | ||
591 | pop_cfun (); | |
592 | current_function_decl = old_decl; | |
dcccac3e | 593 | if (dump_file) |
594 | { | |
b5cebd44 | 595 | if (l->looping) |
596 | fprintf (dump_file, "Function is locally looping.\n"); | |
597 | if (l->can_throw) | |
598 | fprintf (dump_file, "Function is locally throwing.\n"); | |
599 | if (l->pure_const_state == IPA_CONST) | |
600 | fprintf (dump_file, "Function is locally const.\n"); | |
601 | if (l->pure_const_state == IPA_PURE) | |
602 | fprintf (dump_file, "Function is locally pure.\n"); | |
dcccac3e | 603 | } |
b5cebd44 | 604 | return l; |
f7d118a9 | 605 | } |
606 | ||
50828ed8 | 607 | /* Called when new function is inserted to callgraph late. */ |
608 | static void | |
609 | add_new_function (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED) | |
610 | { | |
86844d6c | 611 | if (cgraph_function_body_availability (node) <= AVAIL_OVERWRITABLE) |
612 | return; | |
50828ed8 | 613 | /* There are some shared nodes, in particular the initializers on |
614 | static declarations. We do not need to scan them more than once | |
615 | since all we would be interested in are the addressof | |
616 | operations. */ | |
617 | visited_nodes = pointer_set_create (); | |
b5cebd44 | 618 | set_function_state (node, analyze_function (node, true)); |
50828ed8 | 619 | pointer_set_destroy (visited_nodes); |
620 | visited_nodes = NULL; | |
621 | } | |
622 | ||
86844d6c | 623 | /* Called when new clone is inserted to callgraph late. */ |
624 | ||
625 | static void | |
626 | duplicate_node_data (struct cgraph_node *src, struct cgraph_node *dst, | |
627 | void *data ATTRIBUTE_UNUSED) | |
628 | { | |
629 | if (get_function_state (src)) | |
630 | { | |
631 | funct_state l = XNEW (struct funct_state_d); | |
632 | gcc_assert (!get_function_state (dst)); | |
633 | memcpy (l, get_function_state (src), sizeof (*l)); | |
634 | set_function_state (dst, l); | |
635 | } | |
636 | } | |
637 | ||
638 | /* Called when new clone is inserted to callgraph late. */ | |
639 | ||
640 | static void | |
641 | remove_node_data (struct cgraph_node *node, void *data ATTRIBUTE_UNUSED) | |
642 | { | |
643 | if (get_function_state (node)) | |
644 | { | |
645 | free (get_function_state (node)); | |
646 | set_function_state (node, NULL); | |
647 | } | |
648 | } | |
649 | ||
f7d118a9 | 650 | \f |
cb886925 | 651 | /* Analyze each function in the cgraph to see if it is locally PURE or |
652 | CONST. */ | |
f7d118a9 | 653 | |
cb886925 | 654 | static void |
655 | generate_summary (void) | |
f7d118a9 | 656 | { |
657 | struct cgraph_node *node; | |
f7d118a9 | 658 | |
86844d6c | 659 | node_removal_hook_holder = |
660 | cgraph_add_node_removal_hook (&remove_node_data, NULL); | |
661 | node_duplication_hook_holder = | |
662 | cgraph_add_node_duplication_hook (&duplicate_node_data, NULL); | |
50828ed8 | 663 | function_insertion_hook_holder = |
664 | cgraph_add_function_insertion_hook (&add_new_function, NULL); | |
f7d118a9 | 665 | /* There are some shared nodes, in particular the initializers on |
666 | static declarations. We do not need to scan them more than once | |
667 | since all we would be interested in are the addressof | |
668 | operations. */ | |
669 | visited_nodes = pointer_set_create (); | |
670 | ||
671 | /* Process all of the functions. | |
672 | ||
86844d6c | 673 | We do NOT process any AVAIL_OVERWRITABLE functions, we cannot |
f7d118a9 | 674 | guarantee that what we learn about the one we see will be true |
f0b5f617 | 675 | for the one that overrides it. |
f7d118a9 | 676 | */ |
677 | for (node = cgraph_nodes; node; node = node->next) | |
86844d6c | 678 | if (cgraph_function_body_availability (node) > AVAIL_OVERWRITABLE) |
b5cebd44 | 679 | set_function_state (node, analyze_function (node, true)); |
f7d118a9 | 680 | |
681 | pointer_set_destroy (visited_nodes); | |
682 | visited_nodes = NULL; | |
cb886925 | 683 | } |
684 | ||
17b28e52 | 685 | static bool |
686 | ignore_edge (struct cgraph_edge *e) | |
687 | { | |
688 | return (!e->can_throw_external); | |
689 | } | |
690 | ||
cb886925 | 691 | /* Produce the global information by preforming a transitive closure |
692 | on the local information that was produced by generate_summary. | |
693 | Note that there is no function_transform pass since this only | |
694 | updates the function_decl. */ | |
695 | ||
696 | static unsigned int | |
697 | propagate (void) | |
698 | { | |
699 | struct cgraph_node *node; | |
700 | struct cgraph_node *w; | |
701 | struct cgraph_node **order = | |
702 | XCNEWVEC (struct cgraph_node *, cgraph_n_nodes); | |
703 | int order_pos; | |
704 | int i; | |
705 | struct ipa_dfs_info * w_info; | |
706 | ||
50828ed8 | 707 | cgraph_remove_function_insertion_hook (function_insertion_hook_holder); |
86844d6c | 708 | cgraph_remove_node_duplication_hook (node_duplication_hook_holder); |
709 | cgraph_remove_node_removal_hook (node_removal_hook_holder); | |
17b28e52 | 710 | order_pos = ipa_utils_reduced_inorder (order, true, false, NULL); |
f7d118a9 | 711 | if (dump_file) |
712 | { | |
713 | dump_cgraph (dump_file); | |
714 | ipa_utils_print_order(dump_file, "reduced", order, order_pos); | |
715 | } | |
716 | ||
717 | /* Propagate the local information thru the call graph to produce | |
718 | the global information. All the nodes within a cycle will have | |
719 | the same info so we collapse cycles first. Then we can do the | |
720 | propagation in one pass from the leaves to the roots. */ | |
721 | for (i = 0; i < order_pos; i++ ) | |
722 | { | |
723 | enum pure_const_state_e pure_const_state = IPA_CONST; | |
9c2a0c05 | 724 | bool looping = false; |
54157bf1 | 725 | int count = 0; |
f7d118a9 | 726 | node = order[i]; |
727 | ||
728 | /* Find the worst state for any node in the cycle. */ | |
729 | w = node; | |
730 | while (w) | |
731 | { | |
b5cebd44 | 732 | struct cgraph_edge *e; |
f7d118a9 | 733 | funct_state w_l = get_function_state (w); |
734 | if (pure_const_state < w_l->pure_const_state) | |
735 | pure_const_state = w_l->pure_const_state; | |
736 | ||
9c2a0c05 | 737 | if (w_l->looping) |
738 | looping = true; | |
739 | ||
17b28e52 | 740 | if (pure_const_state == IPA_NEITHER) |
f7d118a9 | 741 | break; |
742 | ||
b5cebd44 | 743 | count++; |
744 | ||
745 | if (count > 1) | |
746 | looping = true; | |
747 | ||
748 | for (e = w->callees; e; e = e->next_callee) | |
f7d118a9 | 749 | { |
b5cebd44 | 750 | struct cgraph_node *y = e->callee; |
54157bf1 | 751 | |
b5cebd44 | 752 | if (cgraph_function_body_availability (y) > AVAIL_OVERWRITABLE) |
f7d118a9 | 753 | { |
b5cebd44 | 754 | funct_state y_l = get_function_state (y); |
755 | if (pure_const_state < y_l->pure_const_state) | |
756 | pure_const_state = y_l->pure_const_state; | |
17b28e52 | 757 | if (pure_const_state == IPA_NEITHER) |
b5cebd44 | 758 | break; |
759 | if (y_l->looping) | |
760 | looping = true; | |
f7d118a9 | 761 | } |
762 | } | |
cda6870f | 763 | w_info = (struct ipa_dfs_info *) w->aux; |
f7d118a9 | 764 | w = w_info->next_cycle; |
765 | } | |
766 | ||
767 | /* Copy back the region's pure_const_state which is shared by | |
768 | all nodes in the region. */ | |
769 | w = node; | |
770 | while (w) | |
771 | { | |
772 | funct_state w_l = get_function_state (w); | |
b5cebd44 | 773 | enum pure_const_state_e this_state = pure_const_state; |
774 | bool this_looping = looping; | |
f7d118a9 | 775 | |
df9b545b | 776 | if (w_l->state_previously_known != IPA_NEITHER |
777 | && this_state > w_l->state_previously_known) | |
778 | this_state = w_l->state_previously_known; | |
779 | if (!w_l->looping_previously_known) | |
780 | this_looping = false; | |
cb886925 | 781 | |
b5cebd44 | 782 | /* All nodes within a cycle share the same info. */ |
783 | w_l->pure_const_state = this_state; | |
784 | w_l->looping = this_looping; | |
785 | ||
786 | switch (this_state) | |
787 | { | |
788 | case IPA_CONST: | |
789 | if (!TREE_READONLY (w->decl) && dump_file) | |
790 | fprintf (dump_file, "Function found to be %sconst: %s\n", | |
791 | this_looping ? "looping " : "", | |
792 | cgraph_node_name (w)); | |
793 | TREE_READONLY (w->decl) = 1; | |
794 | DECL_LOOPING_CONST_OR_PURE_P (w->decl) = this_looping; | |
795 | break; | |
796 | ||
797 | case IPA_PURE: | |
798 | if (!DECL_PURE_P (w->decl) && dump_file) | |
799 | fprintf (dump_file, "Function found to be %spure: %s\n", | |
800 | this_looping ? "looping " : "", | |
801 | cgraph_node_name (w)); | |
802 | DECL_PURE_P (w->decl) = 1; | |
803 | DECL_LOOPING_CONST_OR_PURE_P (w->decl) = this_looping; | |
804 | break; | |
805 | ||
806 | default: | |
807 | break; | |
808 | } | |
17b28e52 | 809 | w_info = (struct ipa_dfs_info *) w->aux; |
810 | w = w_info->next_cycle; | |
811 | } | |
812 | } | |
813 | ||
814 | /* Cleanup. */ | |
815 | for (node = cgraph_nodes; node; node = node->next) | |
816 | { | |
817 | /* Get rid of the aux information. */ | |
818 | if (node->aux) | |
819 | { | |
820 | w_info = (struct ipa_dfs_info *) node->aux; | |
821 | free (node->aux); | |
822 | node->aux = NULL; | |
823 | } | |
824 | } | |
825 | order_pos = ipa_utils_reduced_inorder (order, true, false, ignore_edge); | |
826 | if (dump_file) | |
827 | { | |
828 | dump_cgraph (dump_file); | |
829 | ipa_utils_print_order(dump_file, "reduced for nothrow", order, order_pos); | |
830 | } | |
831 | /* Propagate the local information thru the call graph to produce | |
832 | the global information. All the nodes within a cycle will have | |
833 | the same info so we collapse cycles first. Then we can do the | |
834 | propagation in one pass from the leaves to the roots. */ | |
835 | for (i = 0; i < order_pos; i++ ) | |
836 | { | |
837 | bool can_throw = false; | |
838 | node = order[i]; | |
839 | ||
840 | /* Find the worst state for any node in the cycle. */ | |
841 | w = node; | |
842 | while (w) | |
843 | { | |
844 | struct cgraph_edge *e; | |
845 | funct_state w_l = get_function_state (w); | |
846 | ||
847 | if (w_l->can_throw) | |
848 | can_throw = true; | |
849 | ||
850 | if (can_throw) | |
851 | break; | |
852 | ||
853 | for (e = w->callees; e; e = e->next_callee) | |
854 | { | |
855 | struct cgraph_node *y = e->callee; | |
856 | ||
857 | if (cgraph_function_body_availability (y) > AVAIL_OVERWRITABLE) | |
858 | { | |
859 | funct_state y_l = get_function_state (y); | |
860 | ||
861 | if (can_throw) | |
862 | break; | |
863 | if (y_l->can_throw && !TREE_NOTHROW (w->decl) | |
864 | && e->can_throw_external) | |
865 | can_throw = true; | |
866 | } | |
867 | } | |
868 | w_info = (struct ipa_dfs_info *) w->aux; | |
869 | w = w_info->next_cycle; | |
870 | } | |
871 | ||
872 | /* Copy back the region's pure_const_state which is shared by | |
873 | all nodes in the region. */ | |
874 | w = node; | |
875 | while (w) | |
876 | { | |
ecfab407 | 877 | funct_state w_l = get_function_state (w); |
b5cebd44 | 878 | if (!can_throw && !TREE_NOTHROW (w->decl)) |
879 | { | |
17b28e52 | 880 | struct cgraph_edge *e; |
881 | TREE_NOTHROW (w->decl) = true; | |
882 | for (e = w->callers; e; e = e->next_caller) | |
883 | e->can_throw_external = false; | |
b5cebd44 | 884 | if (dump_file) |
885 | fprintf (dump_file, "Function found to be nothrow: %s\n", | |
886 | cgraph_node_name (w)); | |
f7d118a9 | 887 | } |
ecfab407 | 888 | else if (can_throw && !TREE_NOTHROW (w->decl)) |
889 | w_l->can_throw = true; | |
cda6870f | 890 | w_info = (struct ipa_dfs_info *) w->aux; |
f7d118a9 | 891 | w = w_info->next_cycle; |
892 | } | |
893 | } | |
894 | ||
895 | /* Cleanup. */ | |
896 | for (node = cgraph_nodes; node; node = node->next) | |
cb886925 | 897 | { |
898 | /* Get rid of the aux information. */ | |
899 | if (node->aux) | |
900 | { | |
901 | w_info = (struct ipa_dfs_info *) node->aux; | |
902 | free (node->aux); | |
903 | node->aux = NULL; | |
904 | } | |
86844d6c | 905 | if (cgraph_function_body_availability (node) > AVAIL_OVERWRITABLE) |
cb886925 | 906 | free (get_function_state (node)); |
907 | } | |
908 | ||
f7d118a9 | 909 | free (order); |
86844d6c | 910 | VEC_free (funct_state, heap, funct_state_vec); |
cb886925 | 911 | finish_state (); |
2a1990e9 | 912 | return 0; |
f7d118a9 | 913 | } |
914 | ||
915 | static bool | |
916 | gate_pure_const (void) | |
917 | { | |
86844d6c | 918 | return (flag_ipa_pure_const |
f7d118a9 | 919 | /* Don't bother doing anything if the program has errors. */ |
920 | && !(errorcount || sorrycount)); | |
921 | } | |
922 | ||
26dbec0a | 923 | struct ipa_opt_pass_d pass_ipa_pure_const = |
f7d118a9 | 924 | { |
20099e35 | 925 | { |
cb886925 | 926 | IPA_PASS, |
d3d7bd46 | 927 | "pure-const", /* name */ |
f7d118a9 | 928 | gate_pure_const, /* gate */ |
cb886925 | 929 | propagate, /* execute */ |
f7d118a9 | 930 | NULL, /* sub */ |
931 | NULL, /* next */ | |
932 | 0, /* static_pass_number */ | |
933 | TV_IPA_PURE_CONST, /* tv_id */ | |
934 | 0, /* properties_required */ | |
935 | 0, /* properties_provided */ | |
936 | 0, /* properties_destroyed */ | |
937 | 0, /* todo_flags_start */ | |
20099e35 | 938 | 0 /* todo_flags_finish */ |
cb886925 | 939 | }, |
940 | generate_summary, /* generate_summary */ | |
941 | NULL, /* write_summary */ | |
942 | NULL, /* read_summary */ | |
943 | NULL, /* function_read_summary */ | |
944 | 0, /* TODOs */ | |
945 | NULL, /* function_transform */ | |
946 | NULL /* variable_transform */ | |
f7d118a9 | 947 | }; |
b5cebd44 | 948 | |
949 | /* Simple local pass for pure const discovery reusing the analysis from | |
950 | ipa_pure_const. This pass is effective when executed together with | |
951 | other optimization passes in early optimization pass queue. */ | |
952 | ||
953 | static unsigned int | |
954 | local_pure_const (void) | |
955 | { | |
956 | bool changed = false; | |
957 | funct_state l; | |
958 | ||
959 | /* Because we do not schedule pass_fixup_cfg over whole program after early optimizations | |
960 | we must not promote functions that are called by already processed functions. */ | |
961 | ||
962 | if (function_called_by_processed_nodes_p ()) | |
963 | { | |
964 | if (dump_file) | |
965 | fprintf (dump_file, "Function called in recursive cycle; ignoring\n"); | |
966 | return 0; | |
967 | } | |
968 | ||
969 | l = analyze_function (cgraph_node (current_function_decl), false); | |
970 | if (!l) | |
971 | { | |
972 | if (dump_file) | |
973 | fprintf (dump_file, "Function has wrong visibility; ignoring\n"); | |
974 | return 0; | |
975 | } | |
976 | ||
977 | switch (l->pure_const_state) | |
978 | { | |
979 | case IPA_CONST: | |
980 | if (!TREE_READONLY (current_function_decl)) | |
981 | { | |
982 | TREE_READONLY (current_function_decl) = 1; | |
983 | DECL_LOOPING_CONST_OR_PURE_P (current_function_decl) = l->looping; | |
984 | changed = true; | |
985 | if (dump_file) | |
986 | fprintf (dump_file, "Function found to be %sconst: %s\n", | |
987 | l->looping ? "looping " : "", | |
988 | lang_hooks.decl_printable_name (current_function_decl, | |
989 | 2)); | |
990 | } | |
991 | else if (DECL_LOOPING_CONST_OR_PURE_P (current_function_decl) | |
992 | && !l->looping) | |
993 | { | |
994 | DECL_LOOPING_CONST_OR_PURE_P (current_function_decl) = false; | |
995 | changed = true; | |
996 | if (dump_file) | |
997 | fprintf (dump_file, "Function found to be non-looping: %s\n", | |
998 | lang_hooks.decl_printable_name (current_function_decl, | |
999 | 2)); | |
1000 | } | |
1001 | break; | |
1002 | ||
1003 | case IPA_PURE: | |
1004 | if (!TREE_READONLY (current_function_decl)) | |
1005 | { | |
1006 | DECL_PURE_P (current_function_decl) = 1; | |
1007 | DECL_LOOPING_CONST_OR_PURE_P (current_function_decl) = l->looping; | |
1008 | changed = true; | |
1009 | if (dump_file) | |
1010 | fprintf (dump_file, "Function found to be %spure: %s\n", | |
1011 | l->looping ? "looping " : "", | |
1012 | lang_hooks.decl_printable_name (current_function_decl, | |
1013 | 2)); | |
1014 | } | |
1015 | else if (DECL_LOOPING_CONST_OR_PURE_P (current_function_decl) | |
1016 | && !l->looping) | |
1017 | { | |
1018 | DECL_LOOPING_CONST_OR_PURE_P (current_function_decl) = false; | |
1019 | changed = true; | |
1020 | if (dump_file) | |
1021 | fprintf (dump_file, "Function found to be non-looping: %s\n", | |
1022 | lang_hooks.decl_printable_name (current_function_decl, | |
1023 | 2)); | |
1024 | } | |
1025 | break; | |
1026 | ||
1027 | default: | |
1028 | break; | |
1029 | } | |
1030 | if (!l->can_throw && !TREE_NOTHROW (current_function_decl)) | |
1031 | { | |
17b28e52 | 1032 | struct cgraph_edge *e; |
1033 | ||
1034 | TREE_NOTHROW (current_function_decl) = true; | |
1035 | for (e = cgraph_node (current_function_decl)->callers; | |
1036 | e; e = e->next_caller) | |
1037 | e->can_throw_external = false; | |
b5cebd44 | 1038 | changed = true; |
1039 | if (dump_file) | |
1040 | fprintf (dump_file, "Function found to be nothrow: %s\n", | |
1041 | lang_hooks.decl_printable_name (current_function_decl, | |
1042 | 2)); | |
1043 | } | |
1044 | if (l) | |
1045 | free (l); | |
1046 | if (changed) | |
1047 | return execute_fixup_cfg (); | |
1048 | else | |
1049 | return 0; | |
1050 | } | |
1051 | ||
1052 | struct gimple_opt_pass pass_local_pure_const = | |
1053 | { | |
1054 | { | |
1055 | GIMPLE_PASS, | |
1056 | "local-pure-const", /* name */ | |
1057 | gate_pure_const, /* gate */ | |
1058 | local_pure_const, /* execute */ | |
1059 | NULL, /* sub */ | |
1060 | NULL, /* next */ | |
1061 | 0, /* static_pass_number */ | |
1062 | TV_IPA_PURE_CONST, /* tv_id */ | |
1063 | 0, /* properties_required */ | |
1064 | 0, /* properties_provided */ | |
1065 | 0, /* properties_destroyed */ | |
1066 | 0, /* todo_flags_start */ | |
1067 | 0 /* todo_flags_finish */ | |
1068 | } | |
1069 | }; |