1 | /* Alias analysis for GNU C |
2 | Copyright (C) 1997-2023 Free Software Foundation, Inc. |
3 | Contributed by John Carr (jfc@mit.edu). |
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 |
9 | Software Foundation; either version 3, or (at your option) any later |
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 |
18 | along with GCC; see the file COPYING3. If not see |
19 | <http://www.gnu.org/licenses/>. */ |
20 | |
21 | #include "config.h" |
22 | #include "system.h" |
23 | #include "coretypes.h" |
24 | #include "backend.h" |
25 | #include "target.h" |
26 | #include "rtl.h" |
27 | #include "tree.h" |
28 | #include "gimple.h" |
29 | #include "df.h" |
30 | #include "memmodel.h" |
31 | #include "tm_p.h" |
32 | #include "gimple-ssa.h" |
33 | #include "emit-rtl.h" |
34 | #include "alias.h" |
35 | #include "fold-const.h" |
36 | #include "varasm.h" |
37 | #include "cselib.h" |
38 | #include "langhooks.h" |
39 | #include "cfganal.h" |
40 | #include "rtl-iter.h" |
41 | #include "cgraph.h" |
42 | #include "ipa-utils.h" |
43 | |
44 | /* The aliasing API provided here solves related but different problems: |
45 | |
46 | Say there exists (in c) |
47 | |
48 | struct X { |
49 | struct Y y1; |
50 | struct Z z2; |
51 | } x1, *px1, *px2; |
52 | |
53 | struct Y y2, *py; |
54 | struct Z z2, *pz; |
55 | |
56 | |
57 | py = &x1.y1; |
58 | px2 = &x1; |
59 | |
60 | Consider the four questions: |
61 | |
62 | Can a store to x1 interfere with px2->y1? |
63 | Can a store to x1 interfere with px2->z2? |
64 | Can a store to x1 change the value pointed to by with py? |
65 | Can a store to x1 change the value pointed to by with pz? |
66 | |
67 | The answer to these questions can be yes, yes, yes, and maybe. |
68 | |
69 | The first two questions can be answered with a simple examination |
70 | of the type system. If structure X contains a field of type Y then |
71 | a store through a pointer to an X can overwrite any field that is |
72 | contained (recursively) in an X (unless we know that px1 != px2). |
73 | |
74 | The last two questions can be solved in the same way as the first |
75 | two questions but this is too conservative. The observation is |
76 | that in some cases we can know which (if any) fields are addressed |
77 | and if those addresses are used in bad ways. This analysis may be |
78 | language specific. In C, arbitrary operations may be applied to |
79 | pointers. However, there is some indication that this may be too |
80 | conservative for some C++ types. |
81 | |
82 | The pass ipa-type-escape does this analysis for the types whose |
83 | instances do not escape across the compilation boundary. |
84 | |
85 | Historically in GCC, these two problems were combined and a single |
86 | data structure that was used to represent the solution to these |
87 | problems. We now have two similar but different data structures, |
88 | The data structure to solve the last two questions is similar to |
89 | the first, but does not contain the fields whose address are never |
90 | taken. For types that do escape the compilation unit, the data |
91 | structures will have identical information. |
92 | */ |
93 | |
94 | /* The alias sets assigned to MEMs assist the back-end in determining |
95 | which MEMs can alias which other MEMs. In general, two MEMs in |
96 | different alias sets cannot alias each other, with one important |
97 | exception. Consider something like: |
98 | |
99 | struct S { int i; double d; }; |
100 | |
101 | a store to an `S' can alias something of either type `int' or type |
102 | `double'. (However, a store to an `int' cannot alias a `double' |
103 | and vice versa.) We indicate this via a tree structure that looks |
104 | like: |
105 | struct S |
106 | / \ |
107 | / \ |
108 | |/_ _\| |
109 | int double |
110 | |
111 | (The arrows are directed and point downwards.) |
112 | In this situation we say the alias set for `struct S' is the |
113 | `superset' and that those for `int' and `double' are `subsets'. |
114 | |
115 | To see whether two alias sets can point to the same memory, we must |
116 | see if either alias set is a subset of the other. We need not trace |
117 | past immediate descendants, however, since we propagate all |
118 | grandchildren up one level. |
119 | |
120 | Alias set zero is implicitly a superset of all other alias sets. |
121 | However, this is no actual entry for alias set zero. It is an |
122 | error to attempt to explicitly construct a subset of zero. */ |
123 | |
124 | struct alias_set_hash : int_hash <int, INT_MIN, INT_MIN + 1> {}; |
125 | |
126 | struct GTY(()) alias_set_entry { |
127 | /* The alias set number, as stored in MEM_ALIAS_SET. */ |
128 | alias_set_type alias_set; |
129 | |
130 | /* Nonzero if would have a child of zero: this effectively makes this |
131 | alias set the same as alias set zero. */ |
132 | bool has_zero_child; |
133 | /* Nonzero if alias set corresponds to pointer type itself (i.e. not to |
134 | aggregate contaiing pointer. |
135 | This is used for a special case where we need an universal pointer type |
136 | compatible with all other pointer types. */ |
137 | bool is_pointer; |
138 | /* Nonzero if is_pointer or if one of childs have has_pointer set. */ |
139 | bool has_pointer; |
140 | |
141 | /* The children of the alias set. These are not just the immediate |
142 | children, but, in fact, all descendants. So, if we have: |
143 | |
144 | struct T { struct S s; float f; } |
145 | |
146 | continuing our example above, the children here will be all of |
147 | `int', `double', `float', and `struct S'. */ |
148 | hash_map<alias_set_hash, int> *children; |
149 | }; |
150 | |
151 | static int compare_base_symbol_refs (const_rtx, const_rtx, |
152 | HOST_WIDE_INT * = NULL); |
153 | |
154 | /* Query statistics for the different low-level disambiguators. |
155 | A high-level query may trigger multiple of them. */ |
156 | |
157 | static struct { |
158 | unsigned long long num_alias_zero; |
159 | unsigned long long num_same_alias_set; |
160 | unsigned long long num_same_objects; |
161 | unsigned long long num_volatile; |
162 | unsigned long long num_dag; |
163 | unsigned long long num_universal; |
164 | unsigned long long num_disambiguated; |
165 | } alias_stats; |
166 | |
167 | |
168 | /* Set up all info needed to perform alias analysis on memory references. */ |
169 | |
170 | /* Returns the size in bytes of the mode of X. */ |
171 | #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X))) |
172 | |
173 | /* Cap the number of passes we make over the insns propagating alias |
174 | information through set chains. |
175 | ??? 10 is a completely arbitrary choice. This should be based on the |
176 | maximum loop depth in the CFG, but we do not have this information |
177 | available (even if current_loops _is_ available). */ |
178 | #define MAX_ALIAS_LOOP_PASSES 10 |
179 | |
180 | /* reg_base_value[N] gives an address to which register N is related. |
181 | If all sets after the first add or subtract to the current value |
182 | or otherwise modify it so it does not point to a different top level |
183 | object, reg_base_value[N] is equal to the address part of the source |
184 | of the first set. |
185 | |
186 | A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS |
187 | expressions represent three types of base: |
188 | |
189 | 1. incoming arguments. There is just one ADDRESS to represent all |
190 | arguments, since we do not know at this level whether accesses |
191 | based on different arguments can alias. The ADDRESS has id 0. |
192 | |
193 | 2. stack_pointer_rtx, frame_pointer_rtx, hard_frame_pointer_rtx |
194 | (if distinct from frame_pointer_rtx) and arg_pointer_rtx. |
195 | Each of these rtxes has a separate ADDRESS associated with it, |
196 | each with a negative id. |
197 | |
198 | GCC is (and is required to be) precise in which register it |
199 | chooses to access a particular region of stack. We can therefore |
200 | assume that accesses based on one of these rtxes do not alias |
201 | accesses based on another of these rtxes. |
202 | |
203 | 3. bases that are derived from malloc()ed memory (REG_NOALIAS). |
204 | Each such piece of memory has a separate ADDRESS associated |
205 | with it, each with an id greater than 0. |
206 | |
207 | Accesses based on one ADDRESS do not alias accesses based on other |
208 | ADDRESSes. Accesses based on ADDRESSes in groups (2) and (3) do not |
209 | alias globals either; the ADDRESSes have Pmode to indicate this. |
210 | The ADDRESS in group (1) _may_ alias globals; it has VOIDmode to |
211 | indicate this. */ |
212 | |
213 | static GTY(()) vec<rtx, va_gc> *reg_base_value; |
214 | static rtx *new_reg_base_value; |
215 | |
216 | /* The single VOIDmode ADDRESS that represents all argument bases. |
217 | It has id 0. */ |
218 | static GTY(()) rtx arg_base_value; |
219 | |
220 | /* Used to allocate unique ids to each REG_NOALIAS ADDRESS. */ |
221 | static int unique_id; |
222 | |
223 | /* We preserve the copy of old array around to avoid amount of garbage |
224 | produced. About 8% of garbage produced were attributed to this |
225 | array. */ |
226 | static GTY((deletable)) vec<rtx, va_gc> *old_reg_base_value; |
227 | |
228 | /* Values of XINT (address, 0) of Pmode ADDRESS rtxes for special |
229 | registers. */ |
230 | #define UNIQUE_BASE_VALUE_SP -1 |
231 | #define UNIQUE_BASE_VALUE_ARGP -2 |
232 | #define UNIQUE_BASE_VALUE_FP -3 |
233 | #define UNIQUE_BASE_VALUE_HFP -4 |
234 | |
235 | #define static_reg_base_value \ |
236 | (this_target_rtl->x_static_reg_base_value) |
237 | |
238 | #define REG_BASE_VALUE(X) \ |
239 | (REGNO (X) < vec_safe_length (reg_base_value) \ |
240 | ? (*reg_base_value)[REGNO (X)] : 0) |
241 | |
242 | /* Vector indexed by N giving the initial (unchanging) value known for |
243 | pseudo-register N. This vector is initialized in init_alias_analysis, |
244 | and does not change until end_alias_analysis is called. */ |
245 | static GTY(()) vec<rtx, va_gc> *reg_known_value; |
246 | |
247 | /* Vector recording for each reg_known_value whether it is due to a |
248 | REG_EQUIV note. Future passes (viz., reload) may replace the |
249 | pseudo with the equivalent expression and so we account for the |
250 | dependences that would be introduced if that happens. |
251 | |
252 | The REG_EQUIV notes created in assign_parms may mention the arg |
253 | pointer, and there are explicit insns in the RTL that modify the |
254 | arg pointer. Thus we must ensure that such insns don't get |
255 | scheduled across each other because that would invalidate the |
256 | REG_EQUIV notes. One could argue that the REG_EQUIV notes are |
257 | wrong, but solving the problem in the scheduler will likely give |
258 | better code, so we do it here. */ |
259 | static sbitmap reg_known_equiv_p; |
260 | |
261 | /* True when scanning insns from the start of the rtl to the |
262 | NOTE_INSN_FUNCTION_BEG note. */ |
263 | static bool copying_arguments; |
264 | |
265 | |
266 | /* The splay-tree used to store the various alias set entries. */ |
267 | static GTY (()) vec<alias_set_entry *, va_gc> *alias_sets; |
268 | |
269 | /* Build a decomposed reference object for querying the alias-oracle |
270 | from the MEM rtx and store it in *REF. |
271 | Returns false if MEM is not suitable for the alias-oracle. */ |
272 | |
273 | static bool |
274 | ao_ref_from_mem (ao_ref *ref, const_rtx mem) |
275 | { |
276 | tree expr = MEM_EXPR (mem); |
277 | tree base; |
278 | |
279 | if (!expr) |
280 | return false; |
281 | |
282 | ao_ref_init (ref, expr); |
283 | |
284 | /* Get the base of the reference and see if we have to reject or |
285 | adjust it. */ |
286 | base = ao_ref_base (ref); |
287 | if (base == NULL_TREE) |
288 | return false; |
289 | |
290 | /* The tree oracle doesn't like bases that are neither decls |
291 | nor indirect references of SSA names. */ |
292 | if (!(DECL_P (base) |
293 | || (TREE_CODE (base) == MEM_REF |
294 | && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) |
295 | || (TREE_CODE (base) == TARGET_MEM_REF |
296 | && TREE_CODE (TMR_BASE (base)) == SSA_NAME))) |
297 | return false; |
298 | |
299 | ref->ref_alias_set = MEM_ALIAS_SET (mem); |
300 | |
301 | /* If MEM_OFFSET or MEM_SIZE are unknown what we got from MEM_EXPR |
302 | is conservative, so trust it. */ |
303 | if (!MEM_OFFSET_KNOWN_P (mem) |
304 | || !MEM_SIZE_KNOWN_P (mem)) |
305 | return true; |
306 | |
307 | /* If MEM_OFFSET/MEM_SIZE get us outside of ref->offset/ref->max_size |
308 | drop ref->ref. */ |
309 | if (maybe_lt (MEM_OFFSET (mem), b: 0) |
310 | || (ref->max_size_known_p () |
311 | && maybe_gt ((MEM_OFFSET (mem) + MEM_SIZE (mem)) * BITS_PER_UNIT, |
312 | ref->max_size))) |
313 | ref->ref = NULL_TREE; |
314 | |
315 | /* Refine size and offset we got from analyzing MEM_EXPR by using |
316 | MEM_SIZE and MEM_OFFSET. */ |
317 | |
318 | ref->offset += MEM_OFFSET (mem) * BITS_PER_UNIT; |
319 | ref->size = MEM_SIZE (mem) * BITS_PER_UNIT; |
320 | |
321 | /* The MEM may extend into adjacent fields, so adjust max_size if |
322 | necessary. */ |
323 | if (ref->max_size_known_p ()) |
324 | ref->max_size = upper_bound (a: ref->max_size, b: ref->size); |
325 | |
326 | /* If MEM_OFFSET and MEM_SIZE might get us outside of the base object of |
327 | the MEM_EXPR punt. This happens for STRICT_ALIGNMENT targets a lot. */ |
328 | if (MEM_EXPR (mem) != get_spill_slot_decl (false) |
329 | && (maybe_lt (a: ref->offset, b: 0) |
330 | || (DECL_P (ref->base) |
331 | && (DECL_SIZE (ref->base) == NULL_TREE |
332 | || !poly_int_tree_p (DECL_SIZE (ref->base)) |
333 | || maybe_lt (a: wi::to_poly_offset (DECL_SIZE (ref->base)), |
334 | b: ref->offset + ref->size))))) |
335 | return false; |
336 | |
337 | return true; |
338 | } |
339 | |
340 | /* Query the alias-oracle on whether the two memory rtx X and MEM may |
341 | alias. If TBAA_P is set also apply TBAA. Returns true if the |
342 | two rtxen may alias, false otherwise. */ |
343 | |
344 | static bool |
345 | rtx_refs_may_alias_p (const_rtx x, const_rtx mem, bool tbaa_p) |
346 | { |
347 | ao_ref ref1, ref2; |
348 | |
349 | if (!ao_ref_from_mem (ref: &ref1, mem: x) |
350 | || !ao_ref_from_mem (ref: &ref2, mem)) |
351 | return true; |
352 | |
353 | return refs_may_alias_p_1 (&ref1, &ref2, |
354 | tbaa_p |
355 | && MEM_ALIAS_SET (x) != 0 |
356 | && MEM_ALIAS_SET (mem) != 0); |
357 | } |
358 | |
359 | /* Return true if the ref EARLIER behaves the same as LATER with respect |
360 | to TBAA for every memory reference that might follow LATER. */ |
361 | |
362 | bool |
363 | refs_same_for_tbaa_p (tree earlier, tree later) |
364 | { |
365 | ao_ref earlier_ref, later_ref; |
366 | ao_ref_init (&earlier_ref, earlier); |
367 | ao_ref_init (&later_ref, later); |
368 | alias_set_type earlier_set = ao_ref_alias_set (&earlier_ref); |
369 | alias_set_type later_set = ao_ref_alias_set (&later_ref); |
370 | if (!(earlier_set == later_set |
371 | || alias_set_subset_of (later_set, earlier_set))) |
372 | return false; |
373 | alias_set_type later_base_set = ao_ref_base_alias_set (&later_ref); |
374 | alias_set_type earlier_base_set = ao_ref_base_alias_set (&earlier_ref); |
375 | return (earlier_base_set == later_base_set |
376 | || alias_set_subset_of (later_base_set, earlier_base_set)); |
377 | } |
378 | |
379 | /* Similar to refs_same_for_tbaa_p() but for use on MEM rtxs. */ |
380 | bool |
381 | mems_same_for_tbaa_p (rtx earlier, rtx later) |
382 | { |
383 | gcc_assert (MEM_P (earlier)); |
384 | gcc_assert (MEM_P (later)); |
385 | |
386 | return ((MEM_ALIAS_SET (earlier) == MEM_ALIAS_SET (later) |
387 | || alias_set_subset_of (MEM_ALIAS_SET (later), |
388 | MEM_ALIAS_SET (earlier))) |
389 | && (!MEM_EXPR (earlier) |
390 | || refs_same_for_tbaa_p (MEM_EXPR (earlier), MEM_EXPR (later)))); |
391 | } |
392 | |
393 | /* Returns a pointer to the alias set entry for ALIAS_SET, if there is |
394 | such an entry, or NULL otherwise. */ |
395 | |
396 | static inline alias_set_entry * |
397 | get_alias_set_entry (alias_set_type alias_set) |
398 | { |
399 | return (*alias_sets)[alias_set]; |
400 | } |
401 | |
402 | /* Returns true if the alias sets for MEM1 and MEM2 are such that |
403 | the two MEMs cannot alias each other. */ |
404 | |
405 | static inline bool |
406 | mems_in_disjoint_alias_sets_p (const_rtx mem1, const_rtx mem2) |
407 | { |
408 | return (flag_strict_aliasing |
409 | && ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1), |
410 | MEM_ALIAS_SET (mem2))); |
411 | } |
412 | |
413 | /* Return true if the first alias set is a subset of the second. */ |
414 | |
415 | bool |
416 | alias_set_subset_of (alias_set_type set1, alias_set_type set2) |
417 | { |
418 | alias_set_entry *ase2; |
419 | |
420 | /* Disable TBAA oracle with !flag_strict_aliasing. */ |
421 | if (!flag_strict_aliasing) |
422 | return true; |
423 | |
424 | /* Everything is a subset of the "aliases everything" set. */ |
425 | if (set2 == 0) |
426 | return true; |
427 | |
428 | /* Check if set1 is a subset of set2. */ |
429 | ase2 = get_alias_set_entry (alias_set: set2); |
430 | if (ase2 != 0 |
431 | && (ase2->has_zero_child |
432 | || (ase2->children && ase2->children->get (k: set1)))) |
433 | return true; |
434 | |
435 | /* As a special case we consider alias set of "void *" to be both subset |
436 | and superset of every alias set of a pointer. This extra symmetry does |
437 | not matter for alias_sets_conflict_p but it makes aliasing_component_refs_p |
438 | to return true on the following testcase: |
439 | |
440 | void *ptr; |
441 | char **ptr2=(char **)&ptr; |
442 | *ptr2 = ... |
443 | |
444 | Additionally if a set contains universal pointer, we consider every pointer |
445 | to be a subset of it, but we do not represent this explicitely - doing so |
446 | would require us to update transitive closure each time we introduce new |
447 | pointer type. This makes aliasing_component_refs_p to return true |
448 | on the following testcase: |
449 | |
450 | struct a {void *ptr;} |
451 | char **ptr = (char **)&a.ptr; |
452 | ptr = ... |
453 | |
454 | This makes void * truly universal pointer type. See pointer handling in |
455 | get_alias_set for more details. */ |
456 | if (ase2 && ase2->has_pointer) |
457 | { |
458 | alias_set_entry *ase1 = get_alias_set_entry (alias_set: set1); |
459 | |
460 | if (ase1 && ase1->is_pointer) |
461 | { |
462 | alias_set_type voidptr_set = TYPE_ALIAS_SET (ptr_type_node); |
463 | /* If one is ptr_type_node and other is pointer, then we consider |
464 | them subset of each other. */ |
465 | if (set1 == voidptr_set || set2 == voidptr_set) |
466 | return true; |
467 | /* If SET2 contains universal pointer's alias set, then we consdier |
468 | every (non-universal) pointer. */ |
469 | if (ase2->children && set1 != voidptr_set |
470 | && ase2->children->get (k: voidptr_set)) |
471 | return true; |
472 | } |
473 | } |
474 | return false; |
475 | } |
476 | |
477 | /* Return true if the two specified alias sets may conflict. */ |
478 | |
479 | bool |
480 | alias_sets_conflict_p (alias_set_type set1, alias_set_type set2) |
481 | { |
482 | alias_set_entry *ase1; |
483 | alias_set_entry *ase2; |
484 | |
485 | /* The easy case. */ |
486 | if (alias_sets_must_conflict_p (set1, set2)) |
487 | return true; |
488 | |
489 | /* See if the first alias set is a subset of the second. */ |
490 | ase1 = get_alias_set_entry (alias_set: set1); |
491 | if (ase1 != 0 |
492 | && ase1->children && ase1->children->get (k: set2)) |
493 | { |
494 | ++alias_stats.num_dag; |
495 | return true; |
496 | } |
497 | |
498 | /* Now do the same, but with the alias sets reversed. */ |
499 | ase2 = get_alias_set_entry (alias_set: set2); |
500 | if (ase2 != 0 |
501 | && ase2->children && ase2->children->get (k: set1)) |
502 | { |
503 | ++alias_stats.num_dag; |
504 | return true; |
505 | } |
506 | |
507 | /* We want void * to be compatible with any other pointer without |
508 | really dropping it to alias set 0. Doing so would make it |
509 | compatible with all non-pointer types too. |
510 | |
511 | This is not strictly necessary by the C/C++ language |
512 | standards, but avoids common type punning mistakes. In |
513 | addition to that, we need the existence of such universal |
514 | pointer to implement Fortran's C_PTR type (which is defined as |
515 | type compatible with all C pointers). */ |
516 | if (ase1 && ase2 && ase1->has_pointer && ase2->has_pointer) |
517 | { |
518 | alias_set_type voidptr_set = TYPE_ALIAS_SET (ptr_type_node); |
519 | |
520 | /* If one of the sets corresponds to universal pointer, |
521 | we consider it to conflict with anything that is |
522 | or contains pointer. */ |
523 | if (set1 == voidptr_set || set2 == voidptr_set) |
524 | { |
525 | ++alias_stats.num_universal; |
526 | return true; |
527 | } |
528 | /* If one of sets is (non-universal) pointer and the other |
529 | contains universal pointer, we also get conflict. */ |
530 | if (ase1->is_pointer && set2 != voidptr_set |
531 | && ase2->children && ase2->children->get (k: voidptr_set)) |
532 | { |
533 | ++alias_stats.num_universal; |
534 | return true; |
535 | } |
536 | if (ase2->is_pointer && set1 != voidptr_set |
537 | && ase1->children && ase1->children->get (k: voidptr_set)) |
538 | { |
539 | ++alias_stats.num_universal; |
540 | return true; |
541 | } |
542 | } |
543 | |
544 | ++alias_stats.num_disambiguated; |
545 | |
546 | /* The two alias sets are distinct and neither one is the |
547 | child of the other. Therefore, they cannot conflict. */ |
548 | return false; |
549 | } |
550 | |
551 | /* Return true if the two specified alias sets will always conflict. */ |
552 | |
553 | bool |
554 | alias_sets_must_conflict_p (alias_set_type set1, alias_set_type set2) |
555 | { |
556 | /* Disable TBAA oracle with !flag_strict_aliasing. */ |
557 | if (!flag_strict_aliasing) |
558 | return true; |
559 | if (set1 == 0 || set2 == 0) |
560 | { |
561 | ++alias_stats.num_alias_zero; |
562 | return true; |
563 | } |
564 | if (set1 == set2) |
565 | { |
566 | ++alias_stats.num_same_alias_set; |
567 | return true; |
568 | } |
569 | |
570 | return false; |
571 | } |
572 | |
573 | /* Return true if any MEM object of type T1 will always conflict (using the |
574 | dependency routines in this file) with any MEM object of type T2. |
575 | This is used when allocating temporary storage. If T1 and/or T2 are |
576 | NULL_TREE, it means we know nothing about the storage. */ |
577 | |
578 | bool |
579 | objects_must_conflict_p (tree t1, tree t2) |
580 | { |
581 | alias_set_type set1, set2; |
582 | |
583 | /* If neither has a type specified, we don't know if they'll conflict |
584 | because we may be using them to store objects of various types, for |
585 | example the argument and local variables areas of inlined functions. */ |
586 | if (t1 == 0 && t2 == 0) |
587 | return false; |
588 | |
589 | /* If they are the same type, they must conflict. */ |
590 | if (t1 == t2) |
591 | { |
592 | ++alias_stats.num_same_objects; |
593 | return true; |
594 | } |
595 | /* Likewise if both are volatile. */ |
596 | if (t1 != 0 && TYPE_VOLATILE (t1) && t2 != 0 && TYPE_VOLATILE (t2)) |
597 | { |
598 | ++alias_stats.num_volatile; |
599 | return true; |
600 | } |
601 | |
602 | set1 = t1 ? get_alias_set (t1) : 0; |
603 | set2 = t2 ? get_alias_set (t2) : 0; |
604 | |
605 | /* We can't use alias_sets_conflict_p because we must make sure |
606 | that every subtype of t1 will conflict with every subtype of |
607 | t2 for which a pair of subobjects of these respective subtypes |
608 | overlaps on the stack. */ |
609 | return alias_sets_must_conflict_p (set1, set2); |
610 | } |
611 | |
612 | /* Return true if T is an end of the access path which can be used |
613 | by type based alias oracle. */ |
614 | |
615 | bool |
616 | ends_tbaa_access_path_p (const_tree t) |
617 | { |
618 | switch (TREE_CODE (t)) |
619 | { |
620 | case COMPONENT_REF: |
621 | if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1))) |
622 | return true; |
623 | /* Permit type-punning when accessing a union, provided the access |
624 | is directly through the union. For example, this code does not |
625 | permit taking the address of a union member and then storing |
626 | through it. Even the type-punning allowed here is a GCC |
627 | extension, albeit a common and useful one; the C standard says |
628 | that such accesses have implementation-defined behavior. */ |
629 | else if (TREE_CODE (TREE_TYPE (TREE_OPERAND (t, 0))) == UNION_TYPE) |
630 | return true; |
631 | break; |
632 | |
633 | case ARRAY_REF: |
634 | case ARRAY_RANGE_REF: |
635 | if (TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t, 0)))) |
636 | return true; |
637 | break; |
638 | |
639 | case REALPART_EXPR: |
640 | case IMAGPART_EXPR: |
641 | break; |
642 | |
643 | case BIT_FIELD_REF: |
644 | case VIEW_CONVERT_EXPR: |
645 | /* Bitfields and casts are never addressable. */ |
646 | return true; |
647 | break; |
648 | |
649 | default: |
650 | gcc_unreachable (); |
651 | } |
652 | return false; |
653 | } |
654 | |
655 | /* Return the outermost parent of component present in the chain of |
656 | component references handled by get_inner_reference in T with the |
657 | following property: |
658 | - the component is non-addressable |
659 | or NULL_TREE if no such parent exists. In the former cases, the alias |
660 | set of this parent is the alias set that must be used for T itself. */ |
661 | |
662 | tree |
663 | component_uses_parent_alias_set_from (const_tree t) |
664 | { |
665 | const_tree found = NULL_TREE; |
666 | |
667 | while (handled_component_p (t)) |
668 | { |
669 | if (ends_tbaa_access_path_p (t)) |
670 | found = t; |
671 | |
672 | t = TREE_OPERAND (t, 0); |
673 | } |
674 | |
675 | if (found) |
676 | return TREE_OPERAND (found, 0); |
677 | |
678 | return NULL_TREE; |
679 | } |
680 | |
681 | |
682 | /* Return whether the pointer-type T effective for aliasing may |
683 | access everything and thus the reference has to be assigned |
684 | alias-set zero. */ |
685 | |
686 | static bool |
687 | ref_all_alias_ptr_type_p (const_tree t) |
688 | { |
689 | return (VOID_TYPE_P (TREE_TYPE (t)) |
690 | || TYPE_REF_CAN_ALIAS_ALL (t)); |
691 | } |
692 | |
693 | /* Return the alias set for the memory pointed to by T, which may be |
694 | either a type or an expression. Return -1 if there is nothing |
695 | special about dereferencing T. */ |
696 | |
697 | static alias_set_type |
698 | get_deref_alias_set_1 (tree t) |
699 | { |
700 | /* All we care about is the type. */ |
701 | if (! TYPE_P (t)) |
702 | t = TREE_TYPE (t); |
703 | |
704 | /* If we have an INDIRECT_REF via a void pointer, we don't |
705 | know anything about what that might alias. Likewise if the |
706 | pointer is marked that way. */ |
707 | if (ref_all_alias_ptr_type_p (t)) |
708 | return 0; |
709 | |
710 | return -1; |
711 | } |
712 | |
713 | /* Return the alias set for the memory pointed to by T, which may be |
714 | either a type or an expression. */ |
715 | |
716 | alias_set_type |
717 | get_deref_alias_set (tree t) |
718 | { |
719 | /* If we're not doing any alias analysis, just assume everything |
720 | aliases everything else. */ |
721 | if (!flag_strict_aliasing) |
722 | return 0; |
723 | |
724 | alias_set_type set = get_deref_alias_set_1 (t); |
725 | |
726 | /* Fall back to the alias-set of the pointed-to type. */ |
727 | if (set == -1) |
728 | { |
729 | if (! TYPE_P (t)) |
730 | t = TREE_TYPE (t); |
731 | set = get_alias_set (TREE_TYPE (t)); |
732 | } |
733 | |
734 | return set; |
735 | } |
736 | |
737 | /* Return the pointer-type relevant for TBAA purposes from the |
738 | memory reference tree *T or NULL_TREE in which case *T is |
739 | adjusted to point to the outermost component reference that |
740 | can be used for assigning an alias set. */ |
741 | |
742 | tree |
743 | reference_alias_ptr_type_1 (tree *t) |
744 | { |
745 | tree inner; |
746 | |
747 | /* Get the base object of the reference. */ |
748 | inner = *t; |
749 | while (handled_component_p (t: inner)) |
750 | { |
751 | /* If there is a VIEW_CONVERT_EXPR in the chain we cannot use |
752 | the type of any component references that wrap it to |
753 | determine the alias-set. */ |
754 | if (TREE_CODE (inner) == VIEW_CONVERT_EXPR) |
755 | *t = TREE_OPERAND (inner, 0); |
756 | inner = TREE_OPERAND (inner, 0); |
757 | } |
758 | |
759 | /* Handle pointer dereferences here, they can override the |
760 | alias-set. */ |
761 | if (INDIRECT_REF_P (inner) |
762 | && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner, 0)))) |
763 | return TREE_TYPE (TREE_OPERAND (inner, 0)); |
764 | else if (TREE_CODE (inner) == TARGET_MEM_REF) |
765 | return TREE_TYPE (TMR_OFFSET (inner)); |
766 | else if (TREE_CODE (inner) == MEM_REF |
767 | && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner, 1)))) |
768 | return TREE_TYPE (TREE_OPERAND (inner, 1)); |
769 | |
770 | /* If the innermost reference is a MEM_REF that has a |
771 | conversion embedded treat it like a VIEW_CONVERT_EXPR above, |
772 | using the memory access type for determining the alias-set. */ |
773 | if (TREE_CODE (inner) == MEM_REF |
774 | && (TYPE_MAIN_VARIANT (TREE_TYPE (inner)) |
775 | != TYPE_MAIN_VARIANT |
776 | (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner, 1)))))) |
777 | { |
778 | tree alias_ptrtype = TREE_TYPE (TREE_OPERAND (inner, 1)); |
779 | /* Unless we have the (aggregate) effective type of the access |
780 | somewhere on the access path. If we have for example |
781 | (&a->elts[i])->l.len exposed by abstraction we'd see |
782 | MEM <A> [(B *)a].elts[i].l.len and we can use the alias set |
783 | of 'len' when typeof (MEM <A> [(B *)a].elts[i]) == B for |
784 | example. See PR111715. */ |
785 | tree inner = *t; |
786 | while (handled_component_p (t: inner) |
787 | && (TYPE_MAIN_VARIANT (TREE_TYPE (inner)) |
788 | != TYPE_MAIN_VARIANT (TREE_TYPE (alias_ptrtype)))) |
789 | inner = TREE_OPERAND (inner, 0); |
790 | if (TREE_CODE (inner) == MEM_REF) |
791 | return alias_ptrtype; |
792 | } |
793 | |
794 | /* Otherwise, pick up the outermost object that we could have |
795 | a pointer to. */ |
796 | tree tem = component_uses_parent_alias_set_from (t: *t); |
797 | if (tem) |
798 | *t = tem; |
799 | |
800 | return NULL_TREE; |
801 | } |
802 | |
803 | /* Return the pointer-type relevant for TBAA purposes from the |
804 | gimple memory reference tree T. This is the type to be used for |
805 | the offset operand of MEM_REF or TARGET_MEM_REF replacements of T |
806 | and guarantees that get_alias_set will return the same alias |
807 | set for T and the replacement. */ |
808 | |
809 | tree |
810 | reference_alias_ptr_type (tree t) |
811 | { |
812 | /* If the frontend assigns this alias-set zero, preserve that. */ |
813 | if (lang_hooks.get_alias_set (t) == 0) |
814 | return ptr_type_node; |
815 | |
816 | tree ptype = reference_alias_ptr_type_1 (t: &t); |
817 | /* If there is a given pointer type for aliasing purposes, return it. */ |
818 | if (ptype != NULL_TREE) |
819 | return ptype; |
820 | |
821 | /* Otherwise build one from the outermost component reference we |
822 | may use. */ |
823 | if (TREE_CODE (t) == MEM_REF |
824 | || TREE_CODE (t) == TARGET_MEM_REF) |
825 | return TREE_TYPE (TREE_OPERAND (t, 1)); |
826 | else |
827 | return build_pointer_type (TYPE_MAIN_VARIANT (TREE_TYPE (t))); |
828 | } |
829 | |
830 | /* Return whether the pointer-types T1 and T2 used to determine |
831 | two alias sets of two references will yield the same answer |
832 | from get_deref_alias_set. */ |
833 | |
834 | bool |
835 | alias_ptr_types_compatible_p (tree t1, tree t2) |
836 | { |
837 | if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2)) |
838 | return true; |
839 | |
840 | if (ref_all_alias_ptr_type_p (t: t1) |
841 | || ref_all_alias_ptr_type_p (t: t2)) |
842 | return false; |
843 | |
844 | /* This function originally abstracts from simply comparing |
845 | get_deref_alias_set so that we are sure this still computes |
846 | the same result after LTO type merging is applied. |
847 | When in LTO type merging is done we can actually do this compare. |
848 | */ |
849 | if (in_lto_p) |
850 | return get_deref_alias_set (t: t1) == get_deref_alias_set (t: t2); |
851 | else |
852 | return (TYPE_MAIN_VARIANT (TREE_TYPE (t1)) |
853 | == TYPE_MAIN_VARIANT (TREE_TYPE (t2))); |
854 | } |
855 | |
856 | /* Create emptry alias set entry. */ |
857 | |
858 | alias_set_entry * |
859 | init_alias_set_entry (alias_set_type set) |
860 | { |
861 | alias_set_entry *ase = ggc_alloc<alias_set_entry> (); |
862 | ase->alias_set = set; |
863 | ase->children = NULL; |
864 | ase->has_zero_child = false; |
865 | ase->is_pointer = false; |
866 | ase->has_pointer = false; |
867 | gcc_checking_assert (!get_alias_set_entry (set)); |
868 | (*alias_sets)[set] = ase; |
869 | return ase; |
870 | } |
871 | |
872 | /* Return the alias set for T, which may be either a type or an |
873 | expression. Call language-specific routine for help, if needed. */ |
874 | |
875 | alias_set_type |
876 | get_alias_set (tree t) |
877 | { |
878 | alias_set_type set; |
879 | |
880 | /* We cannot give up with -fno-strict-aliasing because we need to build |
881 | proper type representations for possible functions which are built with |
882 | -fstrict-aliasing. */ |
883 | |
884 | /* return 0 if this or its type is an error. */ |
885 | if (t == error_mark_node |
886 | || (! TYPE_P (t) |
887 | && (TREE_TYPE (t) == 0 || TREE_TYPE (t) == error_mark_node))) |
888 | return 0; |
889 | |
890 | /* We can be passed either an expression or a type. This and the |
891 | language-specific routine may make mutually-recursive calls to each other |
892 | to figure out what to do. At each juncture, we see if this is a tree |
893 | that the language may need to handle specially. First handle things that |
894 | aren't types. */ |
895 | if (! TYPE_P (t)) |
896 | { |
897 | /* Give the language a chance to do something with this tree |
898 | before we look at it. */ |
899 | STRIP_NOPS (t); |
900 | set = lang_hooks.get_alias_set (t); |
901 | if (set != -1) |
902 | return set; |
903 | |
904 | /* Get the alias pointer-type to use or the outermost object |
905 | that we could have a pointer to. */ |
906 | tree ptype = reference_alias_ptr_type_1 (t: &t); |
907 | if (ptype != NULL) |
908 | return get_deref_alias_set (t: ptype); |
909 | |
910 | /* If we've already determined the alias set for a decl, just return |
911 | it. This is necessary for C++ anonymous unions, whose component |
912 | variables don't look like union members (boo!). */ |
913 | if (VAR_P (t) |
914 | && DECL_RTL_SET_P (t) && MEM_P (DECL_RTL (t))) |
915 | return MEM_ALIAS_SET (DECL_RTL (t)); |
916 | |
917 | /* Now all we care about is the type. */ |
918 | t = TREE_TYPE (t); |
919 | } |
920 | |
921 | /* Variant qualifiers don't affect the alias set, so get the main |
922 | variant. */ |
923 | t = TYPE_MAIN_VARIANT (t); |
924 | |
925 | if (AGGREGATE_TYPE_P (t) |
926 | && TYPE_TYPELESS_STORAGE (t)) |
927 | return 0; |
928 | |
929 | /* Always use the canonical type as well. If this is a type that |
930 | requires structural comparisons to identify compatible types |
931 | use alias set zero. */ |
932 | if (TYPE_STRUCTURAL_EQUALITY_P (t)) |
933 | { |
934 | /* Allow the language to specify another alias set for this |
935 | type. */ |
936 | set = lang_hooks.get_alias_set (t); |
937 | if (set != -1) |
938 | return set; |
939 | /* Handle structure type equality for pointer types, arrays and vectors. |
940 | This is easy to do, because the code below ignores canonical types on |
941 | these anyway. This is important for LTO, where TYPE_CANONICAL for |
942 | pointers cannot be meaningfully computed by the frontend. */ |
943 | if (canonical_type_used_p (t)) |
944 | { |
945 | /* In LTO we set canonical types for all types where it makes |
946 | sense to do so. Double check we did not miss some type. */ |
947 | gcc_checking_assert (!in_lto_p || !type_with_alias_set_p (t)); |
948 | return 0; |
949 | } |
950 | } |
951 | else |
952 | { |
953 | t = TYPE_CANONICAL (t); |
954 | gcc_checking_assert (!TYPE_STRUCTURAL_EQUALITY_P (t)); |
955 | } |
956 | |
957 | /* If this is a type with a known alias set, return it. */ |
958 | gcc_checking_assert (t == TYPE_MAIN_VARIANT (t)); |
959 | if (TYPE_ALIAS_SET_KNOWN_P (t)) |
960 | return TYPE_ALIAS_SET (t); |
961 | |
962 | /* We don't want to set TYPE_ALIAS_SET for incomplete types. */ |
963 | if (!COMPLETE_TYPE_P (t)) |
964 | { |
965 | /* For arrays with unknown size the conservative answer is the |
966 | alias set of the element type. */ |
967 | if (TREE_CODE (t) == ARRAY_TYPE) |
968 | return get_alias_set (TREE_TYPE (t)); |
969 | |
970 | /* But return zero as a conservative answer for incomplete types. */ |
971 | return 0; |
972 | } |
973 | |
974 | /* See if the language has special handling for this type. */ |
975 | set = lang_hooks.get_alias_set (t); |
976 | if (set != -1) |
977 | return set; |
978 | |
979 | /* There are no objects of FUNCTION_TYPE, so there's no point in |
980 | using up an alias set for them. (There are, of course, pointers |
981 | and references to functions, but that's different.) */ |
982 | else if (TREE_CODE (t) == FUNCTION_TYPE || TREE_CODE (t) == METHOD_TYPE) |
983 | set = 0; |
984 | |
985 | /* Unless the language specifies otherwise, let vector types alias |
986 | their components. This avoids some nasty type punning issues in |
987 | normal usage. And indeed lets vectors be treated more like an |
988 | array slice. */ |
989 | else if (TREE_CODE (t) == VECTOR_TYPE) |
990 | set = get_alias_set (TREE_TYPE (t)); |
991 | |
992 | /* Unless the language specifies otherwise, treat array types the |
993 | same as their components. This avoids the asymmetry we get |
994 | through recording the components. Consider accessing a |
995 | character(kind=1) through a reference to a character(kind=1)[1:1]. |
996 | Or consider if we want to assign integer(kind=4)[0:D.1387] and |
997 | integer(kind=4)[4] the same alias set or not. |
998 | Just be pragmatic here and make sure the array and its element |
999 | type get the same alias set assigned. */ |
1000 | else if (TREE_CODE (t) == ARRAY_TYPE |
1001 | && (!TYPE_NONALIASED_COMPONENT (t) |
1002 | || TYPE_STRUCTURAL_EQUALITY_P (t))) |
1003 | set = get_alias_set (TREE_TYPE (t)); |
1004 | |
1005 | /* From the former common C and C++ langhook implementation: |
1006 | |
1007 | Unfortunately, there is no canonical form of a pointer type. |
1008 | In particular, if we have `typedef int I', then `int *', and |
1009 | `I *' are different types. So, we have to pick a canonical |
1010 | representative. We do this below. |
1011 | |
1012 | Technically, this approach is actually more conservative that |
1013 | it needs to be. In particular, `const int *' and `int *' |
1014 | should be in different alias sets, according to the C and C++ |
1015 | standard, since their types are not the same, and so, |
1016 | technically, an `int **' and `const int **' cannot point at |
1017 | the same thing. |
1018 | |
1019 | But, the standard is wrong. In particular, this code is |
1020 | legal C++: |
1021 | |
1022 | int *ip; |
1023 | int **ipp = &ip; |
1024 | const int* const* cipp = ipp; |
1025 | And, it doesn't make sense for that to be legal unless you |
1026 | can dereference IPP and CIPP. So, we ignore cv-qualifiers on |
1027 | the pointed-to types. This issue has been reported to the |
1028 | C++ committee. |
1029 | |
1030 | For this reason go to canonical type of the unqalified pointer type. |
1031 | Until GCC 6 this code set all pointers sets to have alias set of |
1032 | ptr_type_node but that is a bad idea, because it prevents disabiguations |
1033 | in between pointers. For Firefox this accounts about 20% of all |
1034 | disambiguations in the program. */ |
1035 | else if (POINTER_TYPE_P (t) && t != ptr_type_node) |
1036 | { |
1037 | tree p; |
1038 | auto_vec <bool, 8> reference; |
1039 | |
1040 | /* Unnest all pointers and references. |
1041 | We also want to make pointer to array/vector equivalent to pointer to |
1042 | its element (see the reasoning above). Skip all those types, too. */ |
1043 | for (p = t; POINTER_TYPE_P (p) |
1044 | || (TREE_CODE (p) == ARRAY_TYPE |
1045 | && (!TYPE_NONALIASED_COMPONENT (p) |
1046 | || !COMPLETE_TYPE_P (p) |
1047 | || TYPE_STRUCTURAL_EQUALITY_P (p))) |
1048 | || TREE_CODE (p) == VECTOR_TYPE; |
1049 | p = TREE_TYPE (p)) |
1050 | { |
1051 | /* Ada supports recursive pointers. Instead of doing recursion |
1052 | check, just give up once the preallocated space of 8 elements |
1053 | is up. In this case just punt to void * alias set. */ |
1054 | if (reference.length () == 8) |
1055 | { |
1056 | p = ptr_type_node; |
1057 | break; |
1058 | } |
1059 | if (TREE_CODE (p) == REFERENCE_TYPE) |
1060 | /* In LTO we want languages that use references to be compatible |
1061 | with languages that use pointers. */ |
1062 | reference.safe_push (obj: true && !in_lto_p); |
1063 | if (TREE_CODE (p) == POINTER_TYPE) |
1064 | reference.safe_push (obj: false); |
1065 | } |
1066 | p = TYPE_MAIN_VARIANT (p); |
1067 | |
1068 | /* In LTO for C++ programs we can turn incomplete types to complete |
1069 | using ODR name lookup. */ |
1070 | if (in_lto_p && TYPE_STRUCTURAL_EQUALITY_P (p) && odr_type_p (t: p)) |
1071 | { |
1072 | p = prevailing_odr_type (type: p); |
1073 | gcc_checking_assert (TYPE_MAIN_VARIANT (p) == p); |
1074 | } |
1075 | |
1076 | /* Make void * compatible with char * and also void **. |
1077 | Programs are commonly violating TBAA by this. |
1078 | |
1079 | We also make void * to conflict with every pointer |
1080 | (see record_component_aliases) and thus it is safe it to use it for |
1081 | pointers to types with TYPE_STRUCTURAL_EQUALITY_P. */ |
1082 | if (TREE_CODE (p) == VOID_TYPE || TYPE_STRUCTURAL_EQUALITY_P (p)) |
1083 | set = get_alias_set (ptr_type_node); |
1084 | else |
1085 | { |
1086 | /* Rebuild pointer type starting from canonical types using |
1087 | unqualified pointers and references only. This way all such |
1088 | pointers will have the same alias set and will conflict with |
1089 | each other. |
1090 | |
1091 | Most of time we already have pointers or references of a given type. |
1092 | If not we build new one just to be sure that if someone later |
1093 | (probably only middle-end can, as we should assign all alias |
1094 | classes only after finishing translation unit) builds the pointer |
1095 | type, the canonical type will match. */ |
1096 | p = TYPE_CANONICAL (p); |
1097 | while (!reference.is_empty ()) |
1098 | { |
1099 | if (reference.pop ()) |
1100 | p = build_reference_type (p); |
1101 | else |
1102 | p = build_pointer_type (p); |
1103 | gcc_checking_assert (p == TYPE_MAIN_VARIANT (p)); |
1104 | /* build_pointer_type should always return the canonical type. |
1105 | For LTO TYPE_CANOINCAL may be NULL, because we do not compute |
1106 | them. Be sure that frontends do not glob canonical types of |
1107 | pointers in unexpected way and that p == TYPE_CANONICAL (p) |
1108 | in all other cases. */ |
1109 | gcc_checking_assert (!TYPE_CANONICAL (p) |
1110 | || p == TYPE_CANONICAL (p)); |
1111 | } |
1112 | |
1113 | /* Assign the alias set to both p and t. |
1114 | We cannot call get_alias_set (p) here as that would trigger |
1115 | infinite recursion when p == t. In other cases it would just |
1116 | trigger unnecesary legwork of rebuilding the pointer again. */ |
1117 | gcc_checking_assert (p == TYPE_MAIN_VARIANT (p)); |
1118 | if (TYPE_ALIAS_SET_KNOWN_P (p)) |
1119 | set = TYPE_ALIAS_SET (p); |
1120 | else |
1121 | { |
1122 | set = new_alias_set (); |
1123 | TYPE_ALIAS_SET (p) = set; |
1124 | } |
1125 | } |
1126 | } |
1127 | /* Alias set of ptr_type_node is special and serve as universal pointer which |
1128 | is TBAA compatible with every other pointer type. Be sure we have the |
1129 | alias set built even for LTO which otherwise keeps all TYPE_CANONICAL |
1130 | of pointer types NULL. */ |
1131 | else if (t == ptr_type_node) |
1132 | set = new_alias_set (); |
1133 | |
1134 | /* Otherwise make a new alias set for this type. */ |
1135 | else |
1136 | { |
1137 | /* Each canonical type gets its own alias set, so canonical types |
1138 | shouldn't form a tree. It doesn't really matter for types |
1139 | we handle specially above, so only check it where it possibly |
1140 | would result in a bogus alias set. */ |
1141 | gcc_checking_assert (TYPE_CANONICAL (t) == t); |
1142 | |
1143 | set = new_alias_set (); |
1144 | } |
1145 | |
1146 | TYPE_ALIAS_SET (t) = set; |
1147 | |
1148 | /* If this is an aggregate type or a complex type, we must record any |
1149 | component aliasing information. */ |
1150 | if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE) |
1151 | record_component_aliases (t); |
1152 | |
1153 | /* We treat pointer types specially in alias_set_subset_of. */ |
1154 | if (POINTER_TYPE_P (t) && set) |
1155 | { |
1156 | alias_set_entry *ase = get_alias_set_entry (alias_set: set); |
1157 | if (!ase) |
1158 | ase = init_alias_set_entry (set); |
1159 | ase->is_pointer = true; |
1160 | ase->has_pointer = true; |
1161 | } |
1162 | |
1163 | return set; |
1164 | } |
1165 | |
1166 | /* Return a brand-new alias set. */ |
1167 | |
1168 | alias_set_type |
1169 | new_alias_set (void) |
1170 | { |
1171 | if (alias_sets == 0) |
1172 | vec_safe_push (v&: alias_sets, obj: (alias_set_entry *) NULL); |
1173 | vec_safe_push (v&: alias_sets, obj: (alias_set_entry *) NULL); |
1174 | return alias_sets->length () - 1; |
1175 | } |
1176 | |
1177 | /* Indicate that things in SUBSET can alias things in SUPERSET, but that |
1178 | not everything that aliases SUPERSET also aliases SUBSET. For example, |
1179 | in C, a store to an `int' can alias a load of a structure containing an |
1180 | `int', and vice versa. But it can't alias a load of a 'double' member |
1181 | of the same structure. Here, the structure would be the SUPERSET and |
1182 | `int' the SUBSET. This relationship is also described in the comment at |
1183 | the beginning of this file. |
1184 | |
1185 | This function should be called only once per SUPERSET/SUBSET pair. |
1186 | |
1187 | It is illegal for SUPERSET to be zero; everything is implicitly a |
1188 | subset of alias set zero. */ |
1189 | |
1190 | void |
1191 | record_alias_subset (alias_set_type superset, alias_set_type subset) |
1192 | { |
1193 | alias_set_entry *superset_entry; |
1194 | alias_set_entry *subset_entry; |
1195 | |
1196 | /* It is possible in complex type situations for both sets to be the same, |
1197 | in which case we can ignore this operation. */ |
1198 | if (superset == subset) |
1199 | return; |
1200 | |
1201 | gcc_assert (superset); |
1202 | |
1203 | superset_entry = get_alias_set_entry (alias_set: superset); |
1204 | if (superset_entry == 0) |
1205 | { |
1206 | /* Create an entry for the SUPERSET, so that we have a place to |
1207 | attach the SUBSET. */ |
1208 | superset_entry = init_alias_set_entry (set: superset); |
1209 | } |
1210 | |
1211 | if (subset == 0) |
1212 | superset_entry->has_zero_child = 1; |
1213 | else |
1214 | { |
1215 | if (!superset_entry->children) |
1216 | superset_entry->children |
1217 | = hash_map<alias_set_hash, int>::create_ggc (size: 64); |
1218 | |
1219 | /* Enter the SUBSET itself as a child of the SUPERSET. If it was |
1220 | already there we're done. */ |
1221 | if (superset_entry->children->put (k: subset, v: 0)) |
1222 | return; |
1223 | |
1224 | subset_entry = get_alias_set_entry (alias_set: subset); |
1225 | /* If there is an entry for the subset, enter all of its children |
1226 | (if they are not already present) as children of the SUPERSET. */ |
1227 | if (subset_entry) |
1228 | { |
1229 | if (subset_entry->has_zero_child) |
1230 | superset_entry->has_zero_child = true; |
1231 | if (subset_entry->has_pointer) |
1232 | superset_entry->has_pointer = true; |
1233 | |
1234 | if (subset_entry->children) |
1235 | { |
1236 | hash_map<alias_set_hash, int>::iterator iter |
1237 | = subset_entry->children->begin (); |
1238 | for (; iter != subset_entry->children->end (); ++iter) |
1239 | superset_entry->children->put (k: (*iter).first, v: (*iter).second); |
1240 | } |
1241 | } |
1242 | } |
1243 | } |
1244 | |
1245 | /* Record that component types of TYPE, if any, are part of SUPERSET for |
1246 | aliasing purposes. For record types, we only record component types |
1247 | for fields that are not marked non-addressable. For array types, we |
1248 | only record the component type if it is not marked non-aliased. */ |
1249 | |
1250 | void |
1251 | record_component_aliases (tree type, alias_set_type superset) |
1252 | { |
1253 | tree field; |
1254 | |
1255 | if (superset == 0) |
1256 | return; |
1257 | |
1258 | switch (TREE_CODE (type)) |
1259 | { |
1260 | case RECORD_TYPE: |
1261 | case UNION_TYPE: |
1262 | case QUAL_UNION_TYPE: |
1263 | { |
1264 | /* LTO non-ODR type merging does not make any difference between |
1265 | component pointer types. We may have |
1266 | |
1267 | struct foo {int *a;}; |
1268 | |
1269 | as TYPE_CANONICAL of |
1270 | |
1271 | struct bar {float *a;}; |
1272 | |
1273 | Because accesses to int * and float * do not alias, we would get |
1274 | false negative when accessing the same memory location by |
1275 | float ** and bar *. We thus record the canonical type as: |
1276 | |
1277 | struct {void *a;}; |
1278 | |
1279 | void * is special cased and works as a universal pointer type. |
1280 | Accesses to it conflicts with accesses to any other pointer |
1281 | type. */ |
1282 | bool void_pointers = in_lto_p |
1283 | && (!odr_type_p (t: type) |
1284 | || !odr_based_tbaa_p (type)); |
1285 | for (field = TYPE_FIELDS (type); field != 0; field = DECL_CHAIN (field)) |
1286 | if (TREE_CODE (field) == FIELD_DECL && !DECL_NONADDRESSABLE_P (field)) |
1287 | { |
1288 | tree t = TREE_TYPE (field); |
1289 | if (void_pointers) |
1290 | { |
1291 | /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their |
1292 | element type and that type has to be normalized to void *, |
1293 | too, in the case it is a pointer. */ |
1294 | while (!canonical_type_used_p (t) && !POINTER_TYPE_P (t)) |
1295 | { |
1296 | gcc_checking_assert (TYPE_STRUCTURAL_EQUALITY_P (t)); |
1297 | t = TREE_TYPE (t); |
1298 | } |
1299 | if (POINTER_TYPE_P (t)) |
1300 | t = ptr_type_node; |
1301 | else if (flag_checking) |
1302 | gcc_checking_assert (get_alias_set (t) |
1303 | == get_alias_set (TREE_TYPE (field))); |
1304 | } |
1305 | |
1306 | alias_set_type set = get_alias_set (t); |
1307 | record_alias_subset (superset, subset: set); |
1308 | /* If the field has alias-set zero make sure to still record |
1309 | any componets of it. This makes sure that for |
1310 | struct A { |
1311 | struct B { |
1312 | int i; |
1313 | char c[4]; |
1314 | } b; |
1315 | }; |
1316 | in C++ even though 'B' has alias-set zero because |
1317 | TYPE_TYPELESS_STORAGE is set, 'A' has the alias-set of |
1318 | 'int' as subset. */ |
1319 | if (set == 0) |
1320 | record_component_aliases (type: t, superset); |
1321 | } |
1322 | } |
1323 | break; |
1324 | |
1325 | case COMPLEX_TYPE: |
1326 | record_alias_subset (superset, subset: get_alias_set (TREE_TYPE (type))); |
1327 | break; |
1328 | |
1329 | /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their |
1330 | element type. */ |
1331 | |
1332 | default: |
1333 | break; |
1334 | } |
1335 | } |
1336 | |
1337 | /* Record that component types of TYPE, if any, are part of that type for |
1338 | aliasing purposes. For record types, we only record component types |
1339 | for fields that are not marked non-addressable. For array types, we |
1340 | only record the component type if it is not marked non-aliased. */ |
1341 | |
1342 | void |
1343 | record_component_aliases (tree type) |
1344 | { |
1345 | alias_set_type superset = get_alias_set (t: type); |
1346 | record_component_aliases (type, superset); |
1347 | } |
1348 | |
1349 | |
1350 | /* Allocate an alias set for use in storing and reading from the varargs |
1351 | spill area. */ |
1352 | |
1353 | static GTY(()) alias_set_type varargs_set = -1; |
1354 | |
1355 | alias_set_type |
1356 | get_varargs_alias_set (void) |
1357 | { |
1358 | #if 1 |
1359 | /* We now lower VA_ARG_EXPR, and there's currently no way to attach the |
1360 | varargs alias set to an INDIRECT_REF (FIXME!), so we can't |
1361 | consistently use the varargs alias set for loads from the varargs |
1362 | area. So don't use it anywhere. */ |
1363 | return 0; |
1364 | #else |
1365 | if (varargs_set == -1) |
1366 | varargs_set = new_alias_set (); |
1367 | |
1368 | return varargs_set; |
1369 | #endif |
1370 | } |
1371 | |
1372 | /* Likewise, but used for the fixed portions of the frame, e.g., register |
1373 | save areas. */ |
1374 | |
1375 | static GTY(()) alias_set_type frame_set = -1; |
1376 | |
1377 | alias_set_type |
1378 | get_frame_alias_set (void) |
1379 | { |
1380 | if (frame_set == -1) |
1381 | frame_set = new_alias_set (); |
1382 | |
1383 | return frame_set; |
1384 | } |
1385 | |
1386 | /* Create a new, unique base with id ID. */ |
1387 | |
1388 | static rtx |
1389 | unique_base_value (HOST_WIDE_INT id) |
1390 | { |
1391 | return gen_rtx_ADDRESS (Pmode, id); |
1392 | } |
1393 | |
1394 | /* Return true if accesses based on any other base value cannot alias |
1395 | those based on X. */ |
1396 | |
1397 | static bool |
1398 | unique_base_value_p (rtx x) |
1399 | { |
1400 | return GET_CODE (x) == ADDRESS && GET_MODE (x) == Pmode; |
1401 | } |
1402 | |
1403 | /* Return true if X is known to be a base value. */ |
1404 | |
1405 | static bool |
1406 | known_base_value_p (rtx x) |
1407 | { |
1408 | switch (GET_CODE (x)) |
1409 | { |
1410 | case LABEL_REF: |
1411 | case SYMBOL_REF: |
1412 | return true; |
1413 | |
1414 | case ADDRESS: |
1415 | /* Arguments may or may not be bases; we don't know for sure. */ |
1416 | return GET_MODE (x) != VOIDmode; |
1417 | |
1418 | default: |
1419 | return false; |
1420 | } |
1421 | } |
1422 | |
1423 | /* Inside SRC, the source of a SET, find a base address. */ |
1424 | |
1425 | static rtx |
1426 | find_base_value (rtx src) |
1427 | { |
1428 | unsigned int regno; |
1429 | scalar_int_mode int_mode; |
1430 | |
1431 | #if defined (FIND_BASE_TERM) |
1432 | /* Try machine-dependent ways to find the base term. */ |
1433 | src = FIND_BASE_TERM (src); |
1434 | #endif |
1435 | |
1436 | switch (GET_CODE (src)) |
1437 | { |
1438 | case SYMBOL_REF: |
1439 | case LABEL_REF: |
1440 | return src; |
1441 | |
1442 | case REG: |
1443 | regno = REGNO (src); |
1444 | /* At the start of a function, argument registers have known base |
1445 | values which may be lost later. Returning an ADDRESS |
1446 | expression here allows optimization based on argument values |
1447 | even when the argument registers are used for other purposes. */ |
1448 | if (regno < FIRST_PSEUDO_REGISTER && copying_arguments) |
1449 | return new_reg_base_value[regno]; |
1450 | |
1451 | /* If a pseudo has a known base value, return it. Do not do this |
1452 | for non-fixed hard regs since it can result in a circular |
1453 | dependency chain for registers which have values at function entry. |
1454 | |
1455 | The test above is not sufficient because the scheduler may move |
1456 | a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */ |
1457 | if ((regno >= FIRST_PSEUDO_REGISTER || fixed_regs[regno]) |
1458 | && regno < vec_safe_length (v: reg_base_value)) |
1459 | { |
1460 | /* If we're inside init_alias_analysis, use new_reg_base_value |
1461 | to reduce the number of relaxation iterations. */ |
1462 | if (new_reg_base_value && new_reg_base_value[regno] |
1463 | && DF_REG_DEF_COUNT (regno) == 1) |
1464 | return new_reg_base_value[regno]; |
1465 | |
1466 | if ((*reg_base_value)[regno]) |
1467 | return (*reg_base_value)[regno]; |
1468 | } |
1469 | |
1470 | return 0; |
1471 | |
1472 | case MEM: |
1473 | /* Check for an argument passed in memory. Only record in the |
1474 | copying-arguments block; it is too hard to track changes |
1475 | otherwise. */ |
1476 | if (copying_arguments |
1477 | && (XEXP (src, 0) == arg_pointer_rtx |
1478 | || (GET_CODE (XEXP (src, 0)) == PLUS |
1479 | && XEXP (XEXP (src, 0), 0) == arg_pointer_rtx))) |
1480 | return arg_base_value; |
1481 | return 0; |
1482 | |
1483 | case CONST: |
1484 | src = XEXP (src, 0); |
1485 | if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS) |
1486 | break; |
1487 | |
1488 | /* fall through */ |
1489 | |
1490 | case PLUS: |
1491 | case MINUS: |
1492 | { |
1493 | rtx temp, src_0 = XEXP (src, 0), src_1 = XEXP (src, 1); |
1494 | |
1495 | /* If either operand is a REG that is a known pointer, then it |
1496 | is the base. */ |
1497 | if (REG_P (src_0) && REG_POINTER (src_0)) |
1498 | return find_base_value (src: src_0); |
1499 | if (REG_P (src_1) && REG_POINTER (src_1)) |
1500 | return find_base_value (src: src_1); |
1501 | |
1502 | /* If either operand is a REG, then see if we already have |
1503 | a known value for it. */ |
1504 | if (REG_P (src_0)) |
1505 | { |
1506 | temp = find_base_value (src: src_0); |
1507 | if (temp != 0) |
1508 | src_0 = temp; |
1509 | } |
1510 | |
1511 | if (REG_P (src_1)) |
1512 | { |
1513 | temp = find_base_value (src: src_1); |
1514 | if (temp!= 0) |
1515 | src_1 = temp; |
1516 | } |
1517 | |
1518 | /* If either base is named object or a special address |
1519 | (like an argument or stack reference), then use it for the |
1520 | base term. */ |
1521 | if (src_0 != 0 && known_base_value_p (x: src_0)) |
1522 | return src_0; |
1523 | |
1524 | if (src_1 != 0 && known_base_value_p (x: src_1)) |
1525 | return src_1; |
1526 | |
1527 | /* Guess which operand is the base address: |
1528 | If either operand is a symbol, then it is the base. If |
1529 | either operand is a CONST_INT, then the other is the base. */ |
1530 | if (CONST_INT_P (src_1) || CONSTANT_P (src_0)) |
1531 | return find_base_value (src: src_0); |
1532 | else if (CONST_INT_P (src_0) || CONSTANT_P (src_1)) |
1533 | return find_base_value (src: src_1); |
1534 | |
1535 | return 0; |
1536 | } |
1537 | |
1538 | case LO_SUM: |
1539 | /* The standard form is (lo_sum reg sym) so look only at the |
1540 | second operand. */ |
1541 | return find_base_value (XEXP (src, 1)); |
1542 | |
1543 | case AND: |
1544 | /* Look through aligning ANDs. And AND with zero or one with |
1545 | the LSB set isn't one (see for example PR92462). */ |
1546 | if (CONST_INT_P (XEXP (src, 1)) |
1547 | && INTVAL (XEXP (src, 1)) != 0 |
1548 | && (INTVAL (XEXP (src, 1)) & 1) == 0) |
1549 | return find_base_value (XEXP (src, 0)); |
1550 | return 0; |
1551 | |
1552 | case TRUNCATE: |
1553 | /* As we do not know which address space the pointer is referring to, we can |
1554 | handle this only if the target does not support different pointer or |
1555 | address modes depending on the address space. */ |
1556 | if (!target_default_pointer_address_modes_p ()) |
1557 | break; |
1558 | if (!is_a <scalar_int_mode> (GET_MODE (src), result: &int_mode) |
1559 | || GET_MODE_PRECISION (mode: int_mode) < GET_MODE_PRECISION (Pmode)) |
1560 | break; |
1561 | /* Fall through. */ |
1562 | case HIGH: |
1563 | case PRE_INC: |
1564 | case PRE_DEC: |
1565 | case POST_INC: |
1566 | case POST_DEC: |
1567 | case PRE_MODIFY: |
1568 | case POST_MODIFY: |
1569 | return find_base_value (XEXP (src, 0)); |
1570 | |
1571 | case ZERO_EXTEND: |
1572 | case SIGN_EXTEND: /* used for NT/Alpha pointers */ |
1573 | /* As we do not know which address space the pointer is referring to, we can |
1574 | handle this only if the target does not support different pointer or |
1575 | address modes depending on the address space. */ |
1576 | if (!target_default_pointer_address_modes_p ()) |
1577 | break; |
1578 | |
1579 | { |
1580 | rtx temp = find_base_value (XEXP (src, 0)); |
1581 | |
1582 | if (temp != 0 && CONSTANT_P (temp)) |
1583 | temp = convert_memory_address (Pmode, temp); |
1584 | |
1585 | return temp; |
1586 | } |
1587 | |
1588 | default: |
1589 | break; |
1590 | } |
1591 | |
1592 | return 0; |
1593 | } |
1594 | |
1595 | /* Called from init_alias_analysis indirectly through note_stores, |
1596 | or directly if DEST is a register with a REG_NOALIAS note attached. |
1597 | SET is null in the latter case. */ |
1598 | |
1599 | /* While scanning insns to find base values, reg_seen[N] is nonzero if |
1600 | register N has been set in this function. */ |
1601 | static sbitmap reg_seen; |
1602 | |
1603 | static void |
1604 | record_set (rtx dest, const_rtx set, void *data ATTRIBUTE_UNUSED) |
1605 | { |
1606 | unsigned regno; |
1607 | rtx src; |
1608 | int n; |
1609 | |
1610 | if (!REG_P (dest)) |
1611 | return; |
1612 | |
1613 | regno = REGNO (dest); |
1614 | |
1615 | gcc_checking_assert (regno < reg_base_value->length ()); |
1616 | |
1617 | n = REG_NREGS (dest); |
1618 | if (n != 1) |
1619 | { |
1620 | while (--n >= 0) |
1621 | { |
1622 | bitmap_set_bit (map: reg_seen, bitno: regno + n); |
1623 | new_reg_base_value[regno + n] = 0; |
1624 | } |
1625 | return; |
1626 | } |
1627 | |
1628 | if (set) |
1629 | { |
1630 | /* A CLOBBER wipes out any old value but does not prevent a previously |
1631 | unset register from acquiring a base address (i.e. reg_seen is not |
1632 | set). */ |
1633 | if (GET_CODE (set) == CLOBBER) |
1634 | { |
1635 | new_reg_base_value[regno] = 0; |
1636 | return; |
1637 | } |
1638 | |
1639 | src = SET_SRC (set); |
1640 | } |
1641 | else |
1642 | { |
1643 | /* There's a REG_NOALIAS note against DEST. */ |
1644 | if (bitmap_bit_p (map: reg_seen, bitno: regno)) |
1645 | { |
1646 | new_reg_base_value[regno] = 0; |
1647 | return; |
1648 | } |
1649 | bitmap_set_bit (map: reg_seen, bitno: regno); |
1650 | new_reg_base_value[regno] = unique_base_value (id: unique_id++); |
1651 | return; |
1652 | } |
1653 | |
1654 | /* If this is not the first set of REGNO, see whether the new value |
1655 | is related to the old one. There are two cases of interest: |
1656 | |
1657 | (1) The register might be assigned an entirely new value |
1658 | that has the same base term as the original set. |
1659 | |
1660 | (2) The set might be a simple self-modification that |
1661 | cannot change REGNO's base value. |
1662 | |
1663 | If neither case holds, reject the original base value as invalid. |
1664 | Note that the following situation is not detected: |
1665 | |
1666 | extern int x, y; int *p = &x; p += (&y-&x); |
1667 | |
1668 | ANSI C does not allow computing the difference of addresses |
1669 | of distinct top level objects. */ |
1670 | if (new_reg_base_value[regno] != 0 |
1671 | && find_base_value (src) != new_reg_base_value[regno]) |
1672 | switch (GET_CODE (src)) |
1673 | { |
1674 | case LO_SUM: |
1675 | case MINUS: |
1676 | if (XEXP (src, 0) != dest && XEXP (src, 1) != dest) |
1677 | new_reg_base_value[regno] = 0; |
1678 | break; |
1679 | case PLUS: |
1680 | /* If the value we add in the PLUS is also a valid base value, |
1681 | this might be the actual base value, and the original value |
1682 | an index. */ |
1683 | { |
1684 | rtx other = NULL_RTX; |
1685 | |
1686 | if (XEXP (src, 0) == dest) |
1687 | other = XEXP (src, 1); |
1688 | else if (XEXP (src, 1) == dest) |
1689 | other = XEXP (src, 0); |
1690 | |
1691 | if (! other || find_base_value (src: other)) |
1692 | new_reg_base_value[regno] = 0; |
1693 | break; |
1694 | } |
1695 | case AND: |
1696 | if (XEXP (src, 0) != dest || !CONST_INT_P (XEXP (src, 1))) |
1697 | new_reg_base_value[regno] = 0; |
1698 | break; |
1699 | default: |
1700 | new_reg_base_value[regno] = 0; |
1701 | break; |
1702 | } |
1703 | /* If this is the first set of a register, record the value. */ |
1704 | else if ((regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno]) |
1705 | && ! bitmap_bit_p (map: reg_seen, bitno: regno) && new_reg_base_value[regno] == 0) |
1706 | new_reg_base_value[regno] = find_base_value (src); |
1707 | |
1708 | bitmap_set_bit (map: reg_seen, bitno: regno); |
1709 | } |
1710 | |
1711 | /* Return REG_BASE_VALUE for REGNO. Selective scheduler uses this to avoid |
1712 | using hard registers with non-null REG_BASE_VALUE for renaming. */ |
1713 | rtx |
1714 | get_reg_base_value (unsigned int regno) |
1715 | { |
1716 | return (*reg_base_value)[regno]; |
1717 | } |
1718 | |
1719 | /* If a value is known for REGNO, return it. */ |
1720 | |
1721 | rtx |
1722 | get_reg_known_value (unsigned int regno) |
1723 | { |
1724 | if (regno >= FIRST_PSEUDO_REGISTER) |
1725 | { |
1726 | regno -= FIRST_PSEUDO_REGISTER; |
1727 | if (regno < vec_safe_length (v: reg_known_value)) |
1728 | return (*reg_known_value)[regno]; |
1729 | } |
1730 | return NULL; |
1731 | } |
1732 | |
1733 | /* Set it. */ |
1734 | |
1735 | static void |
1736 | set_reg_known_value (unsigned int regno, rtx val) |
1737 | { |
1738 | if (regno >= FIRST_PSEUDO_REGISTER) |
1739 | { |
1740 | regno -= FIRST_PSEUDO_REGISTER; |
1741 | if (regno < vec_safe_length (v: reg_known_value)) |
1742 | (*reg_known_value)[regno] = val; |
1743 | } |
1744 | } |
1745 | |
1746 | /* Similarly for reg_known_equiv_p. */ |
1747 | |
1748 | bool |
1749 | get_reg_known_equiv_p (unsigned int regno) |
1750 | { |
1751 | if (regno >= FIRST_PSEUDO_REGISTER) |
1752 | { |
1753 | regno -= FIRST_PSEUDO_REGISTER; |
1754 | if (regno < vec_safe_length (v: reg_known_value)) |
1755 | return bitmap_bit_p (map: reg_known_equiv_p, bitno: regno); |
1756 | } |
1757 | return false; |
1758 | } |
1759 | |
1760 | static void |
1761 | set_reg_known_equiv_p (unsigned int regno, bool val) |
1762 | { |
1763 | if (regno >= FIRST_PSEUDO_REGISTER) |
1764 | { |
1765 | regno -= FIRST_PSEUDO_REGISTER; |
1766 | if (regno < vec_safe_length (v: reg_known_value)) |
1767 | { |
1768 | if (val) |
1769 | bitmap_set_bit (map: reg_known_equiv_p, bitno: regno); |
1770 | else |
1771 | bitmap_clear_bit (map: reg_known_equiv_p, bitno: regno); |
1772 | } |
1773 | } |
1774 | } |
1775 | |
1776 | |
1777 | /* Returns a canonical version of X, from the point of view alias |
1778 | analysis. (For example, if X is a MEM whose address is a register, |
1779 | and the register has a known value (say a SYMBOL_REF), then a MEM |
1780 | whose address is the SYMBOL_REF is returned.) */ |
1781 | |
1782 | rtx |
1783 | canon_rtx (rtx x) |
1784 | { |
1785 | /* Recursively look for equivalences. */ |
1786 | if (REG_P (x) && REGNO (x) >= FIRST_PSEUDO_REGISTER) |
1787 | { |
1788 | rtx t = get_reg_known_value (REGNO (x)); |
1789 | if (t == x) |
1790 | return x; |
1791 | if (t) |
1792 | return canon_rtx (x: t); |
1793 | } |
1794 | |
1795 | if (GET_CODE (x) == PLUS) |
1796 | { |
1797 | rtx x0 = canon_rtx (XEXP (x, 0)); |
1798 | rtx x1 = canon_rtx (XEXP (x, 1)); |
1799 | |
1800 | if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1)) |
1801 | return simplify_gen_binary (code: PLUS, GET_MODE (x), op0: x0, op1: x1); |
1802 | } |
1803 | |
1804 | /* This gives us much better alias analysis when called from |
1805 | the loop optimizer. Note we want to leave the original |
1806 | MEM alone, but need to return the canonicalized MEM with |
1807 | all the flags with their original values. */ |
1808 | else if (MEM_P (x)) |
1809 | x = replace_equiv_address_nv (x, canon_rtx (XEXP (x, 0))); |
1810 | |
1811 | return x; |
1812 | } |
1813 | |
1814 | /* Return true if X and Y are identical-looking rtx's. |
1815 | Expect that X and Y has been already canonicalized. |
1816 | |
1817 | We use the data in reg_known_value above to see if two registers with |
1818 | different numbers are, in fact, equivalent. */ |
1819 | |
1820 | static bool |
1821 | rtx_equal_for_memref_p (const_rtx x, const_rtx y) |
1822 | { |
1823 | int i; |
1824 | int j; |
1825 | enum rtx_code code; |
1826 | const char *fmt; |
1827 | |
1828 | if (x == 0 && y == 0) |
1829 | return true; |
1830 | if (x == 0 || y == 0) |
1831 | return false; |
1832 | |
1833 | if (x == y) |
1834 | return true; |
1835 | |
1836 | code = GET_CODE (x); |
1837 | /* Rtx's of different codes cannot be equal. */ |
1838 | if (code != GET_CODE (y)) |
1839 | return false; |
1840 | |
1841 | /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. |
1842 | (REG:SI x) and (REG:HI x) are NOT equivalent. */ |
1843 | |
1844 | if (GET_MODE (x) != GET_MODE (y)) |
1845 | return false; |
1846 | |
1847 | /* Some RTL can be compared without a recursive examination. */ |
1848 | switch (code) |
1849 | { |
1850 | case REG: |
1851 | return REGNO (x) == REGNO (y); |
1852 | |
1853 | case LABEL_REF: |
1854 | return label_ref_label (ref: x) == label_ref_label (ref: y); |
1855 | |
1856 | case SYMBOL_REF: |
1857 | { |
1858 | HOST_WIDE_INT distance = 0; |
1859 | return (compare_base_symbol_refs (x, y, &distance) == 1 |
1860 | && distance == 0); |
1861 | } |
1862 | |
1863 | case ENTRY_VALUE: |
1864 | /* This is magic, don't go through canonicalization et al. */ |
1865 | return rtx_equal_p (ENTRY_VALUE_EXP (x), ENTRY_VALUE_EXP (y)); |
1866 | |
1867 | case VALUE: |
1868 | CASE_CONST_UNIQUE: |
1869 | /* Pointer equality guarantees equality for these nodes. */ |
1870 | return false; |
1871 | |
1872 | default: |
1873 | break; |
1874 | } |
1875 | |
1876 | /* canon_rtx knows how to handle plus. No need to canonicalize. */ |
1877 | if (code == PLUS) |
1878 | return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)) |
1879 | && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1))) |
1880 | || (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1)) |
1881 | && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0)))); |
1882 | /* For commutative operations, the RTX match if the operand match in any |
1883 | order. Also handle the simple binary and unary cases without a loop. */ |
1884 | if (COMMUTATIVE_P (x)) |
1885 | { |
1886 | rtx xop0 = canon_rtx (XEXP (x, 0)); |
1887 | rtx yop0 = canon_rtx (XEXP (y, 0)); |
1888 | rtx yop1 = canon_rtx (XEXP (y, 1)); |
1889 | |
1890 | return ((rtx_equal_for_memref_p (x: xop0, y: yop0) |
1891 | && rtx_equal_for_memref_p (x: canon_rtx (XEXP (x, 1)), y: yop1)) |
1892 | || (rtx_equal_for_memref_p (x: xop0, y: yop1) |
1893 | && rtx_equal_for_memref_p (x: canon_rtx (XEXP (x, 1)), y: yop0))); |
1894 | } |
1895 | else if (NON_COMMUTATIVE_P (x)) |
1896 | { |
1897 | return (rtx_equal_for_memref_p (x: canon_rtx (XEXP (x, 0)), |
1898 | y: canon_rtx (XEXP (y, 0))) |
1899 | && rtx_equal_for_memref_p (x: canon_rtx (XEXP (x, 1)), |
1900 | y: canon_rtx (XEXP (y, 1)))); |
1901 | } |
1902 | else if (UNARY_P (x)) |
1903 | return rtx_equal_for_memref_p (x: canon_rtx (XEXP (x, 0)), |
1904 | y: canon_rtx (XEXP (y, 0))); |
1905 | |
1906 | /* Compare the elements. If any pair of corresponding elements |
1907 | fail to match, return false for the whole things. |
1908 | |
1909 | Limit cases to types which actually appear in addresses. */ |
1910 | |
1911 | fmt = GET_RTX_FORMAT (code); |
1912 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) |
1913 | { |
1914 | switch (fmt[i]) |
1915 | { |
1916 | case 'i': |
1917 | if (XINT (x, i) != XINT (y, i)) |
1918 | return false; |
1919 | break; |
1920 | |
1921 | case 'p': |
1922 | if (maybe_ne (SUBREG_BYTE (x), SUBREG_BYTE (y))) |
1923 | return false; |
1924 | break; |
1925 | |
1926 | case 'E': |
1927 | /* Two vectors must have the same length. */ |
1928 | if (XVECLEN (x, i) != XVECLEN (y, i)) |
1929 | return false; |
1930 | |
1931 | /* And the corresponding elements must match. */ |
1932 | for (j = 0; j < XVECLEN (x, i); j++) |
1933 | if (rtx_equal_for_memref_p (x: canon_rtx (XVECEXP (x, i, j)), |
1934 | y: canon_rtx (XVECEXP (y, i, j))) == 0) |
1935 | return false; |
1936 | break; |
1937 | |
1938 | case 'e': |
1939 | if (rtx_equal_for_memref_p (x: canon_rtx (XEXP (x, i)), |
1940 | y: canon_rtx (XEXP (y, i))) == 0) |
1941 | return false; |
1942 | break; |
1943 | |
1944 | /* This can happen for asm operands. */ |
1945 | case 's': |
1946 | if (strcmp (XSTR (x, i), XSTR (y, i))) |
1947 | return false; |
1948 | break; |
1949 | |
1950 | /* This can happen for an asm which clobbers memory. */ |
1951 | case '0': |
1952 | break; |
1953 | |
1954 | /* It is believed that rtx's at this level will never |
1955 | contain anything but integers and other rtx's, |
1956 | except for within LABEL_REFs and SYMBOL_REFs. */ |
1957 | default: |
1958 | gcc_unreachable (); |
1959 | } |
1960 | } |
1961 | return true; |
1962 | } |
1963 | |
1964 | static rtx |
1965 | find_base_term (rtx x, vec<std::pair<cselib_val *, |
1966 | struct elt_loc_list *> > &visited_vals) |
1967 | { |
1968 | cselib_val *val; |
1969 | struct elt_loc_list *l, *f; |
1970 | rtx ret; |
1971 | scalar_int_mode int_mode; |
1972 | |
1973 | #if defined (FIND_BASE_TERM) |
1974 | /* Try machine-dependent ways to find the base term. */ |
1975 | x = FIND_BASE_TERM (x); |
1976 | #endif |
1977 | |
1978 | switch (GET_CODE (x)) |
1979 | { |
1980 | case REG: |
1981 | return REG_BASE_VALUE (x); |
1982 | |
1983 | case TRUNCATE: |
1984 | /* As we do not know which address space the pointer is referring to, we can |
1985 | handle this only if the target does not support different pointer or |
1986 | address modes depending on the address space. */ |
1987 | if (!target_default_pointer_address_modes_p ()) |
1988 | return 0; |
1989 | if (!is_a <scalar_int_mode> (GET_MODE (x), result: &int_mode) |
1990 | || GET_MODE_PRECISION (mode: int_mode) < GET_MODE_PRECISION (Pmode)) |
1991 | return 0; |
1992 | /* Fall through. */ |
1993 | case HIGH: |
1994 | case PRE_INC: |
1995 | case PRE_DEC: |
1996 | case POST_INC: |
1997 | case POST_DEC: |
1998 | case PRE_MODIFY: |
1999 | case POST_MODIFY: |
2000 | return find_base_term (XEXP (x, 0), visited_vals); |
2001 | |
2002 | case ZERO_EXTEND: |
2003 | case SIGN_EXTEND: /* Used for Alpha/NT pointers */ |
2004 | /* As we do not know which address space the pointer is referring to, we can |
2005 | handle this only if the target does not support different pointer or |
2006 | address modes depending on the address space. */ |
2007 | if (!target_default_pointer_address_modes_p ()) |
2008 | return 0; |
2009 | |
2010 | { |
2011 | rtx temp = find_base_term (XEXP (x, 0), visited_vals); |
2012 | |
2013 | if (temp != 0 && CONSTANT_P (temp)) |
2014 | temp = convert_memory_address (Pmode, temp); |
2015 | |
2016 | return temp; |
2017 | } |
2018 | |
2019 | case VALUE: |
2020 | val = CSELIB_VAL_PTR (x); |
2021 | ret = NULL_RTX; |
2022 | |
2023 | if (!val) |
2024 | return ret; |
2025 | |
2026 | if (cselib_sp_based_value_p (val)) |
2027 | return static_reg_base_value[STACK_POINTER_REGNUM]; |
2028 | |
2029 | if (visited_vals.length () > (unsigned) param_max_find_base_term_values) |
2030 | return ret; |
2031 | |
2032 | f = val->locs; |
2033 | /* Reset val->locs to avoid infinite recursion. */ |
2034 | if (f) |
2035 | visited_vals.safe_push (obj: std::make_pair (x&: val, y&: f)); |
2036 | val->locs = NULL; |
2037 | |
2038 | for (l = f; l; l = l->next) |
2039 | if (GET_CODE (l->loc) == VALUE |
2040 | && CSELIB_VAL_PTR (l->loc)->locs |
2041 | && !CSELIB_VAL_PTR (l->loc)->locs->next |
2042 | && CSELIB_VAL_PTR (l->loc)->locs->loc == x) |
2043 | continue; |
2044 | else if ((ret = find_base_term (x: l->loc, visited_vals)) != 0) |
2045 | break; |
2046 | |
2047 | return ret; |
2048 | |
2049 | case LO_SUM: |
2050 | /* The standard form is (lo_sum reg sym) so look only at the |
2051 | second operand. */ |
2052 | return find_base_term (XEXP (x, 1), visited_vals); |
2053 | |
2054 | case CONST: |
2055 | x = XEXP (x, 0); |
2056 | if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS) |
2057 | return 0; |
2058 | /* Fall through. */ |
2059 | case PLUS: |
2060 | case MINUS: |
2061 | { |
2062 | rtx tmp1 = XEXP (x, 0); |
2063 | rtx tmp2 = XEXP (x, 1); |
2064 | |
2065 | /* This is a little bit tricky since we have to determine which of |
2066 | the two operands represents the real base address. Otherwise this |
2067 | routine may return the index register instead of the base register. |
2068 | |
2069 | That may cause us to believe no aliasing was possible, when in |
2070 | fact aliasing is possible. |
2071 | |
2072 | We use a few simple tests to guess the base register. Additional |
2073 | tests can certainly be added. For example, if one of the operands |
2074 | is a shift or multiply, then it must be the index register and the |
2075 | other operand is the base register. */ |
2076 | |
2077 | if (tmp1 == pic_offset_table_rtx && CONSTANT_P (tmp2)) |
2078 | return find_base_term (x: tmp2, visited_vals); |
2079 | |
2080 | /* If either operand is known to be a pointer, then prefer it |
2081 | to determine the base term. */ |
2082 | if (REG_P (tmp1) && REG_POINTER (tmp1)) |
2083 | ; |
2084 | else if (REG_P (tmp2) && REG_POINTER (tmp2)) |
2085 | std::swap (a&: tmp1, b&: tmp2); |
2086 | /* If second argument is constant which has base term, prefer it |
2087 | over variable tmp1. See PR64025. */ |
2088 | else if (CONSTANT_P (tmp2) && !CONST_INT_P (tmp2)) |
2089 | std::swap (a&: tmp1, b&: tmp2); |
2090 | |
2091 | /* Go ahead and find the base term for both operands. If either base |
2092 | term is from a pointer or is a named object or a special address |
2093 | (like an argument or stack reference), then use it for the |
2094 | base term. */ |
2095 | rtx base = find_base_term (x: tmp1, visited_vals); |
2096 | if (base != NULL_RTX |
2097 | && ((REG_P (tmp1) && REG_POINTER (tmp1)) |
2098 | || known_base_value_p (x: base))) |
2099 | return base; |
2100 | base = find_base_term (x: tmp2, visited_vals); |
2101 | if (base != NULL_RTX |
2102 | && ((REG_P (tmp2) && REG_POINTER (tmp2)) |
2103 | || known_base_value_p (x: base))) |
2104 | return base; |
2105 | |
2106 | /* We could not determine which of the two operands was the |
2107 | base register and which was the index. So we can determine |
2108 | nothing from the base alias check. */ |
2109 | return 0; |
2110 | } |
2111 | |
2112 | case AND: |
2113 | /* Look through aligning ANDs. And AND with zero or one with |
2114 | the LSB set isn't one (see for example PR92462). */ |
2115 | if (CONST_INT_P (XEXP (x, 1)) |
2116 | && INTVAL (XEXP (x, 1)) != 0 |
2117 | && (INTVAL (XEXP (x, 1)) & 1) == 0) |
2118 | return find_base_term (XEXP (x, 0), visited_vals); |
2119 | return 0; |
2120 | |
2121 | case SYMBOL_REF: |
2122 | case LABEL_REF: |
2123 | return x; |
2124 | |
2125 | default: |
2126 | return 0; |
2127 | } |
2128 | } |
2129 | |
2130 | /* Wrapper around the worker above which removes locs from visited VALUEs |
2131 | to avoid visiting them multiple times. We unwind that changes here. */ |
2132 | |
2133 | static rtx |
2134 | find_base_term (rtx x) |
2135 | { |
2136 | auto_vec<std::pair<cselib_val *, struct elt_loc_list *>, 32> visited_vals; |
2137 | rtx res = find_base_term (x, visited_vals); |
2138 | for (unsigned i = 0; i < visited_vals.length (); ++i) |
2139 | visited_vals[i].first->locs = visited_vals[i].second; |
2140 | return res; |
2141 | } |
2142 | |
2143 | /* Return true if accesses to address X may alias accesses based |
2144 | on the stack pointer. */ |
2145 | |
2146 | bool |
2147 | may_be_sp_based_p (rtx x) |
2148 | { |
2149 | rtx base = find_base_term (x); |
2150 | return !base || base == static_reg_base_value[STACK_POINTER_REGNUM]; |
2151 | } |
2152 | |
2153 | /* BASE1 and BASE2 are decls. Return 1 if they refer to same object, 0 |
2154 | if they refer to different objects and -1 if we cannot decide. */ |
2155 | |
2156 | int |
2157 | compare_base_decls (tree base1, tree base2) |
2158 | { |
2159 | int ret; |
2160 | gcc_checking_assert (DECL_P (base1) && DECL_P (base2)); |
2161 | if (base1 == base2) |
2162 | return 1; |
2163 | |
2164 | /* If we have two register decls with register specification we |
2165 | cannot decide unless their assembler names are the same. */ |
2166 | if (VAR_P (base1) |
2167 | && VAR_P (base2) |
2168 | && DECL_HARD_REGISTER (base1) |
2169 | && DECL_HARD_REGISTER (base2) |
2170 | && DECL_ASSEMBLER_NAME_SET_P (base1) |
2171 | && DECL_ASSEMBLER_NAME_SET_P (base2)) |
2172 | { |
2173 | if (DECL_ASSEMBLER_NAME_RAW (base1) == DECL_ASSEMBLER_NAME_RAW (base2)) |
2174 | return 1; |
2175 | return -1; |
2176 | } |
2177 | |
2178 | /* Declarations of non-automatic variables may have aliases. All other |
2179 | decls are unique. */ |
2180 | if (!decl_in_symtab_p (decl: base1) |
2181 | || !decl_in_symtab_p (decl: base2)) |
2182 | return 0; |
2183 | |
2184 | /* Don't cause symbols to be inserted by the act of checking. */ |
2185 | symtab_node *node1 = symtab_node::get (decl: base1); |
2186 | if (!node1) |
2187 | return 0; |
2188 | symtab_node *node2 = symtab_node::get (decl: base2); |
2189 | if (!node2) |
2190 | return 0; |
2191 | |
2192 | ret = node1->equal_address_to (s2: node2, memory_accessed: true); |
2193 | return ret; |
2194 | } |
2195 | |
2196 | /* Compare SYMBOL_REFs X_BASE and Y_BASE. |
2197 | |
2198 | - Return 1 if Y_BASE - X_BASE is constant, adding that constant |
2199 | to *DISTANCE if DISTANCE is nonnull. |
2200 | |
2201 | - Return 0 if no accesses based on X_BASE can alias Y_BASE. |
2202 | |
2203 | - Return -1 if one of the two results applies, but we can't tell |
2204 | which at compile time. Update DISTANCE in the same way as |
2205 | for a return value of 1, for the case in which that holds. */ |
2206 | |
2207 | static int |
2208 | compare_base_symbol_refs (const_rtx x_base, const_rtx y_base, |
2209 | HOST_WIDE_INT *distance) |
2210 | { |
2211 | tree x_decl = SYMBOL_REF_DECL (x_base); |
2212 | tree y_decl = SYMBOL_REF_DECL (y_base); |
2213 | bool binds_def = true; |
2214 | bool swap = false; |
2215 | |
2216 | if (XSTR (x_base, 0) == XSTR (y_base, 0)) |
2217 | return 1; |
2218 | if (x_decl && y_decl) |
2219 | return compare_base_decls (base1: x_decl, base2: y_decl); |
2220 | if (x_decl || y_decl) |
2221 | { |
2222 | if (!x_decl) |
2223 | { |
2224 | swap = true; |
2225 | std::swap (a&: x_decl, b&: y_decl); |
2226 | std::swap (a&: x_base, b&: y_base); |
2227 | } |
2228 | /* We handle specially only section anchors. Other symbols are |
2229 | either equal (via aliasing) or refer to different objects. */ |
2230 | if (!SYMBOL_REF_HAS_BLOCK_INFO_P (y_base)) |
2231 | return -1; |
2232 | /* Anchors contains static VAR_DECLs and CONST_DECLs. We are safe |
2233 | to ignore CONST_DECLs because they are readonly. */ |
2234 | if (!VAR_P (x_decl) |
2235 | || (!TREE_STATIC (x_decl) && !TREE_PUBLIC (x_decl))) |
2236 | return 0; |
2237 | |
2238 | symtab_node *x_node = symtab_node::get_create (node: x_decl) |
2239 | ->ultimate_alias_target (); |
2240 | /* External variable cannot be in section anchor. */ |
2241 | if (!x_node->definition) |
2242 | return 0; |
2243 | x_base = XEXP (DECL_RTL (x_node->decl), 0); |
2244 | /* If not in anchor, we can disambiguate. */ |
2245 | if (!SYMBOL_REF_HAS_BLOCK_INFO_P (x_base)) |
2246 | return 0; |
2247 | |
2248 | /* We have an alias of anchored variable. If it can be interposed; |
2249 | we must assume it may or may not alias its anchor. */ |
2250 | binds_def = decl_binds_to_current_def_p (x_decl); |
2251 | } |
2252 | /* If we have variable in section anchor, we can compare by offset. */ |
2253 | if (SYMBOL_REF_HAS_BLOCK_INFO_P (x_base) |
2254 | && SYMBOL_REF_HAS_BLOCK_INFO_P (y_base)) |
2255 | { |
2256 | if (SYMBOL_REF_BLOCK (x_base) != SYMBOL_REF_BLOCK (y_base)) |
2257 | return 0; |
2258 | if (distance) |
2259 | *distance += (swap ? -1 : 1) * (SYMBOL_REF_BLOCK_OFFSET (y_base) |
2260 | - SYMBOL_REF_BLOCK_OFFSET (x_base)); |
2261 | return binds_def ? 1 : -1; |
2262 | } |
2263 | /* Either the symbols are equal (via aliasing) or they refer to |
2264 | different objects. */ |
2265 | return -1; |
2266 | } |
2267 | |
2268 | /* Return false if the addresses X and Y are known to point to different |
2269 | objects, true if they might be pointers to the same object. */ |
2270 | |
2271 | static bool |
2272 | base_alias_check (rtx x, rtx x_base, rtx y, rtx y_base, |
2273 | machine_mode x_mode, machine_mode y_mode) |
2274 | { |
2275 | /* If the address itself has no known base see if a known equivalent |
2276 | value has one. If either address still has no known base, nothing |
2277 | is known about aliasing. */ |
2278 | if (x_base == 0) |
2279 | { |
2280 | rtx x_c; |
2281 | |
2282 | if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x) |
2283 | return true; |
2284 | |
2285 | x_base = find_base_term (x: x_c); |
2286 | if (x_base == 0) |
2287 | return true; |
2288 | } |
2289 | |
2290 | if (y_base == 0) |
2291 | { |
2292 | rtx y_c; |
2293 | if (! flag_expensive_optimizations || (y_c = canon_rtx (x: y)) == y) |
2294 | return true; |
2295 | |
2296 | y_base = find_base_term (x: y_c); |
2297 | if (y_base == 0) |
2298 | return true; |
2299 | } |
2300 | |
2301 | /* If the base addresses are equal nothing is known about aliasing. */ |
2302 | if (rtx_equal_p (x_base, y_base)) |
2303 | return true; |
2304 | |
2305 | /* The base addresses are different expressions. If they are not accessed |
2306 | via AND, there is no conflict. We can bring knowledge of object |
2307 | alignment into play here. For example, on alpha, "char a, b;" can |
2308 | alias one another, though "char a; long b;" cannot. AND addresses may |
2309 | implicitly alias surrounding objects; i.e. unaligned access in DImode |
2310 | via AND address can alias all surrounding object types except those |
2311 | with aligment 8 or higher. */ |
2312 | if (GET_CODE (x) == AND && GET_CODE (y) == AND) |
2313 | return true; |
2314 | if (GET_CODE (x) == AND |
2315 | && (!CONST_INT_P (XEXP (x, 1)) |
2316 | || (int) GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1)))) |
2317 | return true; |
2318 | if (GET_CODE (y) == AND |
2319 | && (!CONST_INT_P (XEXP (y, 1)) |
2320 | || (int) GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1)))) |
2321 | return true; |
2322 | |
2323 | /* Differing symbols not accessed via AND never alias. */ |
2324 | if (GET_CODE (x_base) == SYMBOL_REF && GET_CODE (y_base) == SYMBOL_REF) |
2325 | return compare_base_symbol_refs (x_base, y_base) != 0; |
2326 | |
2327 | if (GET_CODE (x_base) != ADDRESS && GET_CODE (y_base) != ADDRESS) |
2328 | return false; |
2329 | |
2330 | if (unique_base_value_p (x: x_base) || unique_base_value_p (x: y_base)) |
2331 | return false; |
2332 | |
2333 | return true; |
2334 | } |
2335 | |
2336 | /* Return TRUE if EXPR refers to a VALUE whose uid is greater than |
2337 | (or equal to) that of V. */ |
2338 | |
2339 | static bool |
2340 | refs_newer_value_p (const_rtx expr, rtx v) |
2341 | { |
2342 | int minuid = CSELIB_VAL_PTR (v)->uid; |
2343 | subrtx_iterator::array_type array; |
2344 | FOR_EACH_SUBRTX (iter, array, expr, NONCONST) |
2345 | if (GET_CODE (*iter) == VALUE && CSELIB_VAL_PTR (*iter)->uid >= minuid) |
2346 | return true; |
2347 | return false; |
2348 | } |
2349 | |
2350 | /* Convert the address X into something we can use. This is done by returning |
2351 | it unchanged unless it is a VALUE or VALUE +/- constant; for VALUE |
2352 | we call cselib to get a more useful rtx. */ |
2353 | |
2354 | rtx |
2355 | get_addr (rtx x) |
2356 | { |
2357 | cselib_val *v; |
2358 | struct elt_loc_list *l; |
2359 | |
2360 | if (GET_CODE (x) != VALUE) |
2361 | { |
2362 | if ((GET_CODE (x) == PLUS || GET_CODE (x) == MINUS) |
2363 | && GET_CODE (XEXP (x, 0)) == VALUE |
2364 | && CONST_SCALAR_INT_P (XEXP (x, 1))) |
2365 | { |
2366 | rtx op0 = get_addr (XEXP (x, 0)); |
2367 | if (op0 != XEXP (x, 0)) |
2368 | { |
2369 | poly_int64 c; |
2370 | if (GET_CODE (x) == PLUS |
2371 | && poly_int_rtx_p (XEXP (x, 1), res: &c)) |
2372 | return plus_constant (GET_MODE (x), op0, c); |
2373 | return simplify_gen_binary (GET_CODE (x), GET_MODE (x), |
2374 | op0, XEXP (x, 1)); |
2375 | } |
2376 | } |
2377 | return x; |
2378 | } |
2379 | v = CSELIB_VAL_PTR (x); |
2380 | if (v) |
2381 | { |
2382 | bool have_equivs = cselib_have_permanent_equivalences (); |
2383 | if (have_equivs) |
2384 | v = canonical_cselib_val (val: v); |
2385 | for (l = v->locs; l; l = l->next) |
2386 | if (CONSTANT_P (l->loc)) |
2387 | return l->loc; |
2388 | for (l = v->locs; l; l = l->next) |
2389 | if (!REG_P (l->loc) && !MEM_P (l->loc) |
2390 | /* Avoid infinite recursion when potentially dealing with |
2391 | var-tracking artificial equivalences, by skipping the |
2392 | equivalences themselves, and not choosing expressions |
2393 | that refer to newer VALUEs. */ |
2394 | && (!have_equivs |
2395 | || (GET_CODE (l->loc) != VALUE |
2396 | && !refs_newer_value_p (expr: l->loc, v: x)))) |
2397 | return l->loc; |
2398 | if (have_equivs) |
2399 | { |
2400 | for (l = v->locs; l; l = l->next) |
2401 | if (REG_P (l->loc) |
2402 | || (GET_CODE (l->loc) != VALUE |
2403 | && !refs_newer_value_p (expr: l->loc, v: x))) |
2404 | return l->loc; |
2405 | /* Return the canonical value. */ |
2406 | return v->val_rtx; |
2407 | } |
2408 | if (v->locs) |
2409 | return v->locs->loc; |
2410 | } |
2411 | return x; |
2412 | } |
2413 | |
2414 | /* Return the address of the (N_REFS + 1)th memory reference to ADDR |
2415 | where SIZE is the size in bytes of the memory reference. If ADDR |
2416 | is not modified by the memory reference then ADDR is returned. */ |
2417 | |
2418 | static rtx |
2419 | addr_side_effect_eval (rtx addr, poly_int64 size, int n_refs) |
2420 | { |
2421 | poly_int64 offset = 0; |
2422 | |
2423 | switch (GET_CODE (addr)) |
2424 | { |
2425 | case PRE_INC: |
2426 | offset = (n_refs + 1) * size; |
2427 | break; |
2428 | case PRE_DEC: |
2429 | offset = -(n_refs + 1) * size; |
2430 | break; |
2431 | case POST_INC: |
2432 | offset = n_refs * size; |
2433 | break; |
2434 | case POST_DEC: |
2435 | offset = -n_refs * size; |
2436 | break; |
2437 | |
2438 | default: |
2439 | return addr; |
2440 | } |
2441 | |
2442 | addr = plus_constant (GET_MODE (addr), XEXP (addr, 0), offset); |
2443 | addr = canon_rtx (x: addr); |
2444 | |
2445 | return addr; |
2446 | } |
2447 | |
2448 | /* Return TRUE if an object X sized at XSIZE bytes and another object |
2449 | Y sized at YSIZE bytes, starting C bytes after X, may overlap. If |
2450 | any of the sizes is zero, assume an overlap, otherwise use the |
2451 | absolute value of the sizes as the actual sizes. */ |
2452 | |
2453 | static inline bool |
2454 | offset_overlap_p (poly_int64 c, poly_int64 xsize, poly_int64 ysize) |
2455 | { |
2456 | if (known_eq (xsize, 0) || known_eq (ysize, 0)) |
2457 | return true; |
2458 | |
2459 | if (maybe_ge (c, 0)) |
2460 | return maybe_gt (maybe_lt (xsize, 0) ? -xsize : xsize, c); |
2461 | else |
2462 | return maybe_gt (maybe_lt (ysize, 0) ? -ysize : ysize, -c); |
2463 | } |
2464 | |
2465 | /* Return one if X and Y (memory addresses) reference the |
2466 | same location in memory or if the references overlap. |
2467 | Return zero if they do not overlap, else return |
2468 | minus one in which case they still might reference the same location. |
2469 | |
2470 | C is an offset accumulator. When |
2471 | C is nonzero, we are testing aliases between X and Y + C. |
2472 | XSIZE is the size in bytes of the X reference, |
2473 | similarly YSIZE is the size in bytes for Y. |
2474 | Expect that canon_rtx has been already called for X and Y. |
2475 | |
2476 | If XSIZE or YSIZE is zero, we do not know the amount of memory being |
2477 | referenced (the reference was BLKmode), so make the most pessimistic |
2478 | assumptions. |
2479 | |
2480 | If XSIZE or YSIZE is negative, we may access memory outside the object |
2481 | being referenced as a side effect. This can happen when using AND to |
2482 | align memory references, as is done on the Alpha. |
2483 | |
2484 | Nice to notice that varying addresses cannot conflict with fp if no |
2485 | local variables had their addresses taken, but that's too hard now. |
2486 | |
2487 | ??? Contrary to the tree alias oracle this does not return |
2488 | one for X + non-constant and Y + non-constant when X and Y are equal. |
2489 | If that is fixed the TBAA hack for union type-punning can be removed. */ |
2490 | |
2491 | static int |
2492 | memrefs_conflict_p (poly_int64 xsize, rtx x, poly_int64 ysize, rtx y, |
2493 | poly_int64 c) |
2494 | { |
2495 | if (GET_CODE (x) == VALUE) |
2496 | { |
2497 | if (REG_P (y)) |
2498 | { |
2499 | struct elt_loc_list *l = NULL; |
2500 | if (CSELIB_VAL_PTR (x)) |
2501 | for (l = canonical_cselib_val (CSELIB_VAL_PTR (x))->locs; |
2502 | l; l = l->next) |
2503 | if (REG_P (l->loc) && rtx_equal_for_memref_p (x: l->loc, y)) |
2504 | break; |
2505 | if (l) |
2506 | x = y; |
2507 | else |
2508 | x = get_addr (x); |
2509 | } |
2510 | /* Don't call get_addr if y is the same VALUE. */ |
2511 | else if (x != y) |
2512 | x = get_addr (x); |
2513 | } |
2514 | if (GET_CODE (y) == VALUE) |
2515 | { |
2516 | if (REG_P (x)) |
2517 | { |
2518 | struct elt_loc_list *l = NULL; |
2519 | if (CSELIB_VAL_PTR (y)) |
2520 | for (l = canonical_cselib_val (CSELIB_VAL_PTR (y))->locs; |
2521 | l; l = l->next) |
2522 | if (REG_P (l->loc) && rtx_equal_for_memref_p (x: l->loc, y: x)) |
2523 | break; |
2524 | if (l) |
2525 | y = x; |
2526 | else |
2527 | y = get_addr (x: y); |
2528 | } |
2529 | /* Don't call get_addr if x is the same VALUE. */ |
2530 | else if (y != x) |
2531 | y = get_addr (x: y); |
2532 | } |
2533 | if (GET_CODE (x) == HIGH) |
2534 | x = XEXP (x, 0); |
2535 | else if (GET_CODE (x) == LO_SUM) |
2536 | x = XEXP (x, 1); |
2537 | else |
2538 | x = addr_side_effect_eval (addr: x, size: maybe_lt (a: xsize, b: 0) ? -xsize : xsize, n_refs: 0); |
2539 | if (GET_CODE (y) == HIGH) |
2540 | y = XEXP (y, 0); |
2541 | else if (GET_CODE (y) == LO_SUM) |
2542 | y = XEXP (y, 1); |
2543 | else |
2544 | y = addr_side_effect_eval (addr: y, size: maybe_lt (a: ysize, b: 0) ? -ysize : ysize, n_refs: 0); |
2545 | |
2546 | if (GET_CODE (x) == SYMBOL_REF && GET_CODE (y) == SYMBOL_REF) |
2547 | { |
2548 | HOST_WIDE_INT distance = 0; |
2549 | int cmp = compare_base_symbol_refs (x_base: x, y_base: y, distance: &distance); |
2550 | |
2551 | /* If both decls are the same, decide by offsets. */ |
2552 | if (cmp == 1) |
2553 | return offset_overlap_p (c: c + distance, xsize, ysize); |
2554 | /* Assume a potential overlap for symbolic addresses that went |
2555 | through alignment adjustments (i.e., that have negative |
2556 | sizes), because we can't know how far they are from each |
2557 | other. */ |
2558 | if (maybe_lt (a: xsize, b: 0) || maybe_lt (a: ysize, b: 0)) |
2559 | return -1; |
2560 | /* If decls are different or we know by offsets that there is no overlap, |
2561 | we win. */ |
2562 | if (!cmp || !offset_overlap_p (c: c + distance, xsize, ysize)) |
2563 | return 0; |
2564 | /* Decls may or may not be different and offsets overlap....*/ |
2565 | return -1; |
2566 | } |
2567 | else if (rtx_equal_for_memref_p (x, y)) |
2568 | { |
2569 | return offset_overlap_p (c, xsize, ysize); |
2570 | } |
2571 | |
2572 | /* This code used to check for conflicts involving stack references and |
2573 | globals but the base address alias code now handles these cases. */ |
2574 | |
2575 | if (GET_CODE (x) == PLUS) |
2576 | { |
2577 | /* The fact that X is canonicalized means that this |
2578 | PLUS rtx is canonicalized. */ |
2579 | rtx x0 = XEXP (x, 0); |
2580 | rtx x1 = XEXP (x, 1); |
2581 | |
2582 | /* However, VALUEs might end up in different positions even in |
2583 | canonical PLUSes. Comparing their addresses is enough. */ |
2584 | if (x0 == y) |
2585 | return memrefs_conflict_p (xsize, x: x1, ysize, const0_rtx, c); |
2586 | else if (x1 == y) |
2587 | return memrefs_conflict_p (xsize, x: x0, ysize, const0_rtx, c); |
2588 | |
2589 | poly_int64 cx1, cy1; |
2590 | if (GET_CODE (y) == PLUS) |
2591 | { |
2592 | /* The fact that Y is canonicalized means that this |
2593 | PLUS rtx is canonicalized. */ |
2594 | rtx y0 = XEXP (y, 0); |
2595 | rtx y1 = XEXP (y, 1); |
2596 | |
2597 | if (x0 == y1) |
2598 | return memrefs_conflict_p (xsize, x: x1, ysize, y: y0, c); |
2599 | if (x1 == y0) |
2600 | return memrefs_conflict_p (xsize, x: x0, ysize, y: y1, c); |
2601 | |
2602 | if (rtx_equal_for_memref_p (x: x1, y: y1)) |
2603 | return memrefs_conflict_p (xsize, x: x0, ysize, y: y0, c); |
2604 | if (rtx_equal_for_memref_p (x: x0, y: y0)) |
2605 | return memrefs_conflict_p (xsize, x: x1, ysize, y: y1, c); |
2606 | if (poly_int_rtx_p (x: x1, res: &cx1)) |
2607 | { |
2608 | if (poly_int_rtx_p (x: y1, res: &cy1)) |
2609 | return memrefs_conflict_p (xsize, x: x0, ysize, y: y0, |
2610 | c: c - cx1 + cy1); |
2611 | else |
2612 | return memrefs_conflict_p (xsize, x: x0, ysize, y, c: c - cx1); |
2613 | } |
2614 | else if (poly_int_rtx_p (x: y1, res: &cy1)) |
2615 | return memrefs_conflict_p (xsize, x, ysize, y: y0, c: c + cy1); |
2616 | |
2617 | return -1; |
2618 | } |
2619 | else if (poly_int_rtx_p (x: x1, res: &cx1)) |
2620 | return memrefs_conflict_p (xsize, x: x0, ysize, y, c: c - cx1); |
2621 | } |
2622 | else if (GET_CODE (y) == PLUS) |
2623 | { |
2624 | /* The fact that Y is canonicalized means that this |
2625 | PLUS rtx is canonicalized. */ |
2626 | rtx y0 = XEXP (y, 0); |
2627 | rtx y1 = XEXP (y, 1); |
2628 | |
2629 | if (x == y0) |
2630 | return memrefs_conflict_p (xsize, const0_rtx, ysize, y: y1, c); |
2631 | if (x == y1) |
2632 | return memrefs_conflict_p (xsize, const0_rtx, ysize, y: y0, c); |
2633 | |
2634 | poly_int64 cy1; |
2635 | if (poly_int_rtx_p (x: y1, res: &cy1)) |
2636 | return memrefs_conflict_p (xsize, x, ysize, y: y0, c: c + cy1); |
2637 | else |
2638 | return -1; |
2639 | } |
2640 | |
2641 | if (GET_CODE (x) == GET_CODE (y)) |
2642 | switch (GET_CODE (x)) |
2643 | { |
2644 | case MULT: |
2645 | { |
2646 | /* Handle cases where we expect the second operands to be the |
2647 | same, and check only whether the first operand would conflict |
2648 | or not. */ |
2649 | rtx x0, y0; |
2650 | rtx x1 = canon_rtx (XEXP (x, 1)); |
2651 | rtx y1 = canon_rtx (XEXP (y, 1)); |
2652 | if (! rtx_equal_for_memref_p (x: x1, y: y1)) |
2653 | return -1; |
2654 | x0 = canon_rtx (XEXP (x, 0)); |
2655 | y0 = canon_rtx (XEXP (y, 0)); |
2656 | if (rtx_equal_for_memref_p (x: x0, y: y0)) |
2657 | return offset_overlap_p (c, xsize, ysize); |
2658 | |
2659 | /* Can't properly adjust our sizes. */ |
2660 | poly_int64 c1; |
2661 | if (!poly_int_rtx_p (x: x1, res: &c1) |
2662 | || !can_div_trunc_p (a: xsize, b: c1, quotient: &xsize) |
2663 | || !can_div_trunc_p (a: ysize, b: c1, quotient: &ysize) |
2664 | || !can_div_trunc_p (a: c, b: c1, quotient: &c)) |
2665 | return -1; |
2666 | return memrefs_conflict_p (xsize, x: x0, ysize, y: y0, c); |
2667 | } |
2668 | |
2669 | default: |
2670 | break; |
2671 | } |
2672 | |
2673 | /* Deal with alignment ANDs by adjusting offset and size so as to |
2674 | cover the maximum range, without taking any previously known |
2675 | alignment into account. Make a size negative after such an |
2676 | adjustments, so that, if we end up with e.g. two SYMBOL_REFs, we |
2677 | assume a potential overlap, because they may end up in contiguous |
2678 | memory locations and the stricter-alignment access may span over |
2679 | part of both. */ |
2680 | if (GET_CODE (x) == AND && CONST_INT_P (XEXP (x, 1))) |
2681 | { |
2682 | HOST_WIDE_INT sc = INTVAL (XEXP (x, 1)); |
2683 | unsigned HOST_WIDE_INT uc = sc; |
2684 | if (sc < 0 && pow2_or_zerop (x: -uc)) |
2685 | { |
2686 | if (maybe_gt (xsize, 0)) |
2687 | xsize = -xsize; |
2688 | if (maybe_ne (a: xsize, b: 0)) |
2689 | xsize += sc + 1; |
2690 | c -= sc + 1; |
2691 | return memrefs_conflict_p (xsize, x: canon_rtx (XEXP (x, 0)), |
2692 | ysize, y, c); |
2693 | } |
2694 | } |
2695 | if (GET_CODE (y) == AND && CONST_INT_P (XEXP (y, 1))) |
2696 | { |
2697 | HOST_WIDE_INT sc = INTVAL (XEXP (y, 1)); |
2698 | unsigned HOST_WIDE_INT uc = sc; |
2699 | if (sc < 0 && pow2_or_zerop (x: -uc)) |
2700 | { |
2701 | if (maybe_gt (ysize, 0)) |
2702 | ysize = -ysize; |
2703 | if (maybe_ne (a: ysize, b: 0)) |
2704 | ysize += sc + 1; |
2705 | c += sc + 1; |
2706 | return memrefs_conflict_p (xsize, x, |
2707 | ysize, y: canon_rtx (XEXP (y, 0)), c); |
2708 | } |
2709 | } |
2710 | |
2711 | if (CONSTANT_P (x)) |
2712 | { |
2713 | poly_int64 cx, cy; |
2714 | if (poly_int_rtx_p (x, res: &cx) && poly_int_rtx_p (x: y, res: &cy)) |
2715 | { |
2716 | c += cy - cx; |
2717 | return offset_overlap_p (c, xsize, ysize); |
2718 | } |
2719 | |
2720 | if (GET_CODE (x) == CONST) |
2721 | { |
2722 | if (GET_CODE (y) == CONST) |
2723 | return memrefs_conflict_p (xsize, x: canon_rtx (XEXP (x, 0)), |
2724 | ysize, y: canon_rtx (XEXP (y, 0)), c); |
2725 | else |
2726 | return memrefs_conflict_p (xsize, x: canon_rtx (XEXP (x, 0)), |
2727 | ysize, y, c); |
2728 | } |
2729 | if (GET_CODE (y) == CONST) |
2730 | return memrefs_conflict_p (xsize, x, ysize, |
2731 | y: canon_rtx (XEXP (y, 0)), c); |
2732 | |
2733 | /* Assume a potential overlap for symbolic addresses that went |
2734 | through alignment adjustments (i.e., that have negative |
2735 | sizes), because we can't know how far they are from each |
2736 | other. */ |
2737 | if (CONSTANT_P (y)) |
2738 | return (maybe_lt (a: xsize, b: 0) |
2739 | || maybe_lt (a: ysize, b: 0) |
2740 | || offset_overlap_p (c, xsize, ysize)); |
2741 | |
2742 | return -1; |
2743 | } |
2744 | |
2745 | return -1; |
2746 | } |
2747 | |
2748 | /* Functions to compute memory dependencies. |
2749 | |
2750 | Since we process the insns in execution order, we can build tables |
2751 | to keep track of what registers are fixed (and not aliased), what registers |
2752 | are varying in known ways, and what registers are varying in unknown |
2753 | ways. |
2754 | |
2755 | If both memory references are volatile, then there must always be a |
2756 | dependence between the two references, since their order cannot be |
2757 | changed. A volatile and non-volatile reference can be interchanged |
2758 | though. |
2759 | |
2760 | We also must allow AND addresses, because they may generate accesses |
2761 | outside the object being referenced. This is used to generate aligned |
2762 | addresses from unaligned addresses, for instance, the alpha |
2763 | storeqi_unaligned pattern. */ |
2764 | |
2765 | /* Read dependence: X is read after read in MEM takes place. There can |
2766 | only be a dependence here if both reads are volatile, or if either is |
2767 | an explicit barrier. */ |
2768 | |
2769 | bool |
2770 | read_dependence (const_rtx mem, const_rtx x) |
2771 | { |
2772 | if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) |
2773 | return true; |
2774 | if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER |
2775 | || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) |
2776 | return true; |
2777 | return false; |
2778 | } |
2779 | |
2780 | /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */ |
2781 | |
2782 | static tree |
2783 | decl_for_component_ref (tree x) |
2784 | { |
2785 | do |
2786 | { |
2787 | x = TREE_OPERAND (x, 0); |
2788 | } |
2789 | while (x && TREE_CODE (x) == COMPONENT_REF); |
2790 | |
2791 | return x && DECL_P (x) ? x : NULL_TREE; |
2792 | } |
2793 | |
2794 | /* Walk up the COMPONENT_REF list in X and adjust *OFFSET to compensate |
2795 | for the offset of the field reference. *KNOWN_P says whether the |
2796 | offset is known. */ |
2797 | |
2798 | static void |
2799 | adjust_offset_for_component_ref (tree x, bool *known_p, |
2800 | poly_int64 *offset) |
2801 | { |
2802 | if (!*known_p) |
2803 | return; |
2804 | do |
2805 | { |
2806 | tree xoffset = component_ref_field_offset (x); |
2807 | tree field = TREE_OPERAND (x, 1); |
2808 | if (!poly_int_tree_p (t: xoffset)) |
2809 | { |
2810 | *known_p = false; |
2811 | return; |
2812 | } |
2813 | |
2814 | poly_offset_int woffset |
2815 | = (wi::to_poly_offset (t: xoffset) |
2816 | + (wi::to_offset (DECL_FIELD_BIT_OFFSET (field)) |
2817 | >> LOG2_BITS_PER_UNIT) |
2818 | + *offset); |
2819 | if (!woffset.to_shwi (r: offset)) |
2820 | { |
2821 | *known_p = false; |
2822 | return; |
2823 | } |
2824 | |
2825 | x = TREE_OPERAND (x, 0); |
2826 | } |
2827 | while (x && TREE_CODE (x) == COMPONENT_REF); |
2828 | } |
2829 | |
2830 | /* Return true if we can determine the exprs corresponding to memrefs |
2831 | X and Y and they do not overlap. |
2832 | If LOOP_VARIANT is set, skip offset-based disambiguation */ |
2833 | |
2834 | bool |
2835 | nonoverlapping_memrefs_p (const_rtx x, const_rtx y, bool loop_invariant) |
2836 | { |
2837 | tree exprx = MEM_EXPR (x), expry = MEM_EXPR (y); |
2838 | rtx rtlx, rtly; |
2839 | rtx basex, basey; |
2840 | bool moffsetx_known_p, moffsety_known_p; |
2841 | poly_int64 moffsetx = 0, moffsety = 0; |
2842 | poly_int64 offsetx = 0, offsety = 0, sizex, sizey; |
2843 | |
2844 | /* Unless both have exprs, we can't tell anything. */ |
2845 | if (exprx == 0 || expry == 0) |
2846 | return false; |
2847 | |
2848 | /* For spill-slot accesses make sure we have valid offsets. */ |
2849 | if ((exprx == get_spill_slot_decl (false) |
2850 | && ! MEM_OFFSET_KNOWN_P (x)) |
2851 | || (expry == get_spill_slot_decl (false) |
2852 | && ! MEM_OFFSET_KNOWN_P (y))) |
2853 | return false; |
2854 | |
2855 | /* If the field reference test failed, look at the DECLs involved. */ |
2856 | moffsetx_known_p = MEM_OFFSET_KNOWN_P (x); |
2857 | if (moffsetx_known_p) |
2858 | moffsetx = MEM_OFFSET (x); |
2859 | if (TREE_CODE (exprx) == COMPONENT_REF) |
2860 | { |
2861 | tree t = decl_for_component_ref (x: exprx); |
2862 | if (! t) |
2863 | return false; |
2864 | adjust_offset_for_component_ref (x: exprx, known_p: &moffsetx_known_p, offset: &moffsetx); |
2865 | exprx = t; |
2866 | } |
2867 | |
2868 | moffsety_known_p = MEM_OFFSET_KNOWN_P (y); |
2869 | if (moffsety_known_p) |
2870 | moffsety = MEM_OFFSET (y); |
2871 | if (TREE_CODE (expry) == COMPONENT_REF) |
2872 | { |
2873 | tree t = decl_for_component_ref (x: expry); |
2874 | if (! t) |
2875 | return false; |
2876 | adjust_offset_for_component_ref (x: expry, known_p: &moffsety_known_p, offset: &moffsety); |
2877 | expry = t; |
2878 | } |
2879 | |
2880 | if (! DECL_P (exprx) || ! DECL_P (expry)) |
2881 | return false; |
2882 | |
2883 | /* If we refer to different gimple registers, or one gimple register |
2884 | and one non-gimple-register, we know they can't overlap. First, |
2885 | gimple registers don't have their addresses taken. Now, there |
2886 | could be more than one stack slot for (different versions of) the |
2887 | same gimple register, but we can presumably tell they don't |
2888 | overlap based on offsets from stack base addresses elsewhere. |
2889 | It's important that we don't proceed to DECL_RTL, because gimple |
2890 | registers may not pass DECL_RTL_SET_P, and make_decl_rtl won't be |
2891 | able to do anything about them since no SSA information will have |
2892 | remained to guide it. */ |
2893 | if (is_gimple_reg (exprx) || is_gimple_reg (expry)) |
2894 | return exprx != expry |
2895 | || (moffsetx_known_p && moffsety_known_p |
2896 | && MEM_SIZE_KNOWN_P (x) && MEM_SIZE_KNOWN_P (y) |
2897 | && !offset_overlap_p (c: moffsety - moffsetx, |
2898 | MEM_SIZE (x), MEM_SIZE (y))); |
2899 | |
2900 | /* With invalid code we can end up storing into the constant pool. |
2901 | Bail out to avoid ICEing when creating RTL for this. |
2902 | See gfortran.dg/lto/20091028-2_0.f90. */ |
2903 | if (TREE_CODE (exprx) == CONST_DECL |
2904 | || TREE_CODE (expry) == CONST_DECL) |
2905 | return true; |
2906 | |
2907 | /* If one decl is known to be a function or label in a function and |
2908 | the other is some kind of data, they can't overlap. */ |
2909 | if ((TREE_CODE (exprx) == FUNCTION_DECL |
2910 | || TREE_CODE (exprx) == LABEL_DECL) |
2911 | != (TREE_CODE (expry) == FUNCTION_DECL |
2912 | || TREE_CODE (expry) == LABEL_DECL)) |
2913 | return true; |
2914 | |
2915 | /* If either of the decls doesn't have DECL_RTL set (e.g. marked as |
2916 | living in multiple places), we can't tell anything. Exception |
2917 | are FUNCTION_DECLs for which we can create DECL_RTL on demand. */ |
2918 | if ((!DECL_RTL_SET_P (exprx) && TREE_CODE (exprx) != FUNCTION_DECL) |
2919 | || (!DECL_RTL_SET_P (expry) && TREE_CODE (expry) != FUNCTION_DECL)) |
2920 | return false; |
2921 | |
2922 | rtlx = DECL_RTL (exprx); |
2923 | rtly = DECL_RTL (expry); |
2924 | |
2925 | /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they |
2926 | can't overlap unless they are the same because we never reuse that part |
2927 | of the stack frame used for locals for spilled pseudos. */ |
2928 | if ((!MEM_P (rtlx) || !MEM_P (rtly)) |
2929 | && ! rtx_equal_p (rtlx, rtly)) |
2930 | return true; |
2931 | |
2932 | /* If we have MEMs referring to different address spaces (which can |
2933 | potentially overlap), we cannot easily tell from the addresses |
2934 | whether the references overlap. */ |
2935 | if (MEM_P (rtlx) && MEM_P (rtly) |
2936 | && MEM_ADDR_SPACE (rtlx) != MEM_ADDR_SPACE (rtly)) |
2937 | return false; |
2938 | |
2939 | /* Get the base and offsets of both decls. If either is a register, we |
2940 | know both are and are the same, so use that as the base. The only |
2941 | we can avoid overlap is if we can deduce that they are nonoverlapping |
2942 | pieces of that decl, which is very rare. */ |
2943 | basex = MEM_P (rtlx) ? XEXP (rtlx, 0) : rtlx; |
2944 | basex = strip_offset_and_add (x: basex, offset: &offsetx); |
2945 | |
2946 | basey = MEM_P (rtly) ? XEXP (rtly, 0) : rtly; |
2947 | basey = strip_offset_and_add (x: basey, offset: &offsety); |
2948 | |
2949 | /* If the bases are different, we know they do not overlap if both |
2950 | are constants or if one is a constant and the other a pointer into the |
2951 | stack frame. Otherwise a different base means we can't tell if they |
2952 | overlap or not. */ |
2953 | if (compare_base_decls (base1: exprx, base2: expry) == 0) |
2954 | return ((CONSTANT_P (basex) && CONSTANT_P (basey)) |
2955 | || (CONSTANT_P (basex) && REG_P (basey) |
2956 | && REGNO_PTR_FRAME_P (REGNO (basey))) |
2957 | || (CONSTANT_P (basey) && REG_P (basex) |
2958 | && REGNO_PTR_FRAME_P (REGNO (basex)))); |
2959 | |
2960 | /* Offset based disambiguation not appropriate for loop invariant */ |
2961 | if (loop_invariant) |
2962 | return false; |
2963 | |
2964 | /* Offset based disambiguation is OK even if we do not know that the |
2965 | declarations are necessarily different |
2966 | (i.e. compare_base_decls (exprx, expry) == -1) */ |
2967 | |
2968 | sizex = (!MEM_P (rtlx) ? poly_int64 (GET_MODE_SIZE (GET_MODE (rtlx))) |
2969 | : MEM_SIZE_KNOWN_P (rtlx) ? MEM_SIZE (rtlx) |
2970 | : -1); |
2971 | sizey = (!MEM_P (rtly) ? poly_int64 (GET_MODE_SIZE (GET_MODE (rtly))) |
2972 | : MEM_SIZE_KNOWN_P (rtly) ? MEM_SIZE (rtly) |
2973 | : -1); |
2974 | |
2975 | /* If we have an offset for either memref, it can update the values computed |
2976 | above. */ |
2977 | if (moffsetx_known_p) |
2978 | offsetx += moffsetx, sizex -= moffsetx; |
2979 | if (moffsety_known_p) |
2980 | offsety += moffsety, sizey -= moffsety; |
2981 | |
2982 | /* If a memref has both a size and an offset, we can use the smaller size. |
2983 | We can't do this if the offset isn't known because we must view this |
2984 | memref as being anywhere inside the DECL's MEM. */ |
2985 | if (MEM_SIZE_KNOWN_P (x) && moffsetx_known_p) |
2986 | sizex = MEM_SIZE (x); |
2987 | if (MEM_SIZE_KNOWN_P (y) && moffsety_known_p) |
2988 | sizey = MEM_SIZE (y); |
2989 | |
2990 | return !ranges_maybe_overlap_p (pos1: offsetx, size1: sizex, pos2: offsety, size2: sizey); |
2991 | } |
2992 | |
2993 | /* Helper for true_dependence and canon_true_dependence. |
2994 | Checks for true dependence: X is read after store in MEM takes place. |
2995 | |
2996 | If MEM_CANONICALIZED is FALSE, then X_ADDR and MEM_ADDR should be |
2997 | NULL_RTX, and the canonical addresses of MEM and X are both computed |
2998 | here. If MEM_CANONICALIZED, then MEM must be already canonicalized. |
2999 | |
3000 | If X_ADDR is non-NULL, it is used in preference of XEXP (x, 0). |
3001 | |
3002 | Returns true if there is a true dependence, false otherwise. */ |
3003 | |
3004 | static bool |
3005 | true_dependence_1 (const_rtx mem, machine_mode mem_mode, rtx mem_addr, |
3006 | const_rtx x, rtx x_addr, bool mem_canonicalized) |
3007 | { |
3008 | rtx true_mem_addr; |
3009 | rtx base; |
3010 | int ret; |
3011 | |
3012 | gcc_checking_assert (mem_canonicalized ? (mem_addr != NULL_RTX) |
3013 | : (mem_addr == NULL_RTX && x_addr == NULL_RTX)); |
3014 | |
3015 | if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) |
3016 | return true; |
3017 | |
3018 | /* (mem:BLK (scratch)) is a special mechanism to conflict with everything. |
3019 | This is used in epilogue deallocation functions, and in cselib. */ |
3020 | if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH) |
3021 | return true; |
3022 | if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH) |
3023 | return true; |
3024 | if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER |
3025 | || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) |
3026 | return true; |
3027 | |
3028 | if (! x_addr) |
3029 | x_addr = XEXP (x, 0); |
3030 | x_addr = get_addr (x: x_addr); |
3031 | |
3032 | if (! mem_addr) |
3033 | { |
3034 | mem_addr = XEXP (mem, 0); |
3035 | if (mem_mode == VOIDmode) |
3036 | mem_mode = GET_MODE (mem); |
3037 | } |
3038 | true_mem_addr = get_addr (x: mem_addr); |
3039 | |
3040 | /* Read-only memory is by definition never modified, and therefore can't |
3041 | conflict with anything. However, don't assume anything when AND |
3042 | addresses are involved and leave to the code below to determine |
3043 | dependence. We don't expect to find read-only set on MEM, but |
3044 | stupid user tricks can produce them, so don't die. */ |
3045 | if (MEM_READONLY_P (x) |
3046 | && GET_CODE (x_addr) != AND |
3047 | && GET_CODE (true_mem_addr) != AND) |
3048 | return false; |
3049 | |
3050 | /* If we have MEMs referring to different address spaces (which can |
3051 | potentially overlap), we cannot easily tell from the addresses |
3052 | whether the references overlap. */ |
3053 | if (MEM_ADDR_SPACE (mem) != MEM_ADDR_SPACE (x)) |
3054 | return true; |
3055 | |
3056 | base = find_base_term (x: x_addr); |
3057 | if (base && (GET_CODE (base) == LABEL_REF |
3058 | || (GET_CODE (base) == SYMBOL_REF |
3059 | && CONSTANT_POOL_ADDRESS_P (base)))) |
3060 | return false; |
3061 | |
3062 | rtx mem_base = find_base_term (x: true_mem_addr); |
3063 | if (! base_alias_check (x: x_addr, x_base: base, y: true_mem_addr, y_base: mem_base, |
3064 | GET_MODE (x), y_mode: mem_mode)) |
3065 | return false; |
3066 | |
3067 | x_addr = canon_rtx (x: x_addr); |
3068 | if (!mem_canonicalized) |
3069 | mem_addr = canon_rtx (x: true_mem_addr); |
3070 | |
3071 | if ((ret = memrefs_conflict_p (xsize: GET_MODE_SIZE (mode: mem_mode), x: mem_addr, |
3072 | SIZE_FOR_MODE (x), y: x_addr, c: 0)) != -1) |
3073 | return !!ret; |
3074 | |
3075 | if (mems_in_disjoint_alias_sets_p (mem1: x, mem2: mem)) |
3076 | return false; |
3077 | |
3078 | if (nonoverlapping_memrefs_p (x: mem, y: x, loop_invariant: false)) |
3079 | return false; |
3080 | |
3081 | return rtx_refs_may_alias_p (x, mem, tbaa_p: true); |
3082 | } |
3083 | |
3084 | /* True dependence: X is read after store in MEM takes place. */ |
3085 | |
3086 | bool |
3087 | true_dependence (const_rtx mem, machine_mode mem_mode, const_rtx x) |
3088 | { |
3089 | return true_dependence_1 (mem, mem_mode, NULL_RTX, |
3090 | x, NULL_RTX, /*mem_canonicalized=*/false); |
3091 | } |
3092 | |
3093 | /* Canonical true dependence: X is read after store in MEM takes place. |
3094 | Variant of true_dependence which assumes MEM has already been |
3095 | canonicalized (hence we no longer do that here). |
3096 | The mem_addr argument has been added, since true_dependence_1 computed |
3097 | this value prior to canonicalizing. */ |
3098 | |
3099 | bool |
3100 | canon_true_dependence (const_rtx mem, machine_mode mem_mode, rtx mem_addr, |
3101 | const_rtx x, rtx x_addr) |
3102 | { |
3103 | return true_dependence_1 (mem, mem_mode, mem_addr, |
3104 | x, x_addr, /*mem_canonicalized=*/true); |
3105 | } |
3106 | |
3107 | /* Returns true if a write to X might alias a previous read from |
3108 | (or, if WRITEP is true, a write to) MEM. |
3109 | If X_CANONCALIZED is true, then X_ADDR is the canonicalized address of X, |
3110 | and X_MODE the mode for that access. |
3111 | If MEM_CANONICALIZED is true, MEM is canonicalized. */ |
3112 | |
3113 | static bool |
3114 | write_dependence_p (const_rtx mem, |
3115 | const_rtx x, machine_mode x_mode, rtx x_addr, |
3116 | bool mem_canonicalized, bool x_canonicalized, bool writep) |
3117 | { |
3118 | rtx mem_addr; |
3119 | rtx true_mem_addr, true_x_addr; |
3120 | rtx base; |
3121 | int ret; |
3122 | |
3123 | gcc_checking_assert (x_canonicalized |
3124 | ? (x_addr != NULL_RTX |
3125 | && (x_mode != VOIDmode || GET_MODE (x) == VOIDmode)) |
3126 | : (x_addr == NULL_RTX && x_mode == VOIDmode)); |
3127 | |
3128 | if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) |
3129 | return true; |
3130 | |
3131 | /* (mem:BLK (scratch)) is a special mechanism to conflict with everything. |
3132 | This is used in epilogue deallocation functions. */ |
3133 | if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH) |
3134 | return true; |
3135 | if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH) |
3136 | return true; |
3137 | if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER |
3138 | || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) |
3139 | return true; |
3140 | |
3141 | if (!x_addr) |
3142 | x_addr = XEXP (x, 0); |
3143 | true_x_addr = get_addr (x: x_addr); |
3144 | |
3145 | mem_addr = XEXP (mem, 0); |
3146 | true_mem_addr = get_addr (x: mem_addr); |
3147 | |
3148 | /* A read from read-only memory can't conflict with read-write memory. |
3149 | Don't assume anything when AND addresses are involved and leave to |
3150 | the code below to determine dependence. */ |
3151 | if (!writep |
3152 | && MEM_READONLY_P (mem) |
3153 | && GET_CODE (true_x_addr) != AND |
3154 | && GET_CODE (true_mem_addr) != AND) |
3155 | return false; |
3156 | |
3157 | /* If we have MEMs referring to different address spaces (which can |
3158 | potentially overlap), we cannot easily tell from the addresses |
3159 | whether the references overlap. */ |
3160 | if (MEM_ADDR_SPACE (mem) != MEM_ADDR_SPACE (x)) |
3161 | return true; |
3162 | |
3163 | base = find_base_term (x: true_mem_addr); |
3164 | if (! writep |
3165 | && base |
3166 | && (GET_CODE (base) == LABEL_REF |
3167 | || (GET_CODE (base) == SYMBOL_REF |
3168 | && CONSTANT_POOL_ADDRESS_P (base)))) |
3169 | return false; |
3170 | |
3171 | rtx x_base = find_base_term (x: true_x_addr); |
3172 | if (! base_alias_check (x: true_x_addr, x_base, y: true_mem_addr, y_base: base, |
3173 | GET_MODE (x), GET_MODE (mem))) |
3174 | return false; |
3175 | |
3176 | if (!x_canonicalized) |
3177 | { |
3178 | x_addr = canon_rtx (x: true_x_addr); |
3179 | x_mode = GET_MODE (x); |
3180 | } |
3181 | if (!mem_canonicalized) |
3182 | mem_addr = canon_rtx (x: true_mem_addr); |
3183 | |
3184 | if ((ret = memrefs_conflict_p (SIZE_FOR_MODE (mem), x: mem_addr, |
3185 | ysize: GET_MODE_SIZE (mode: x_mode), y: x_addr, c: 0)) != -1) |
3186 | return !!ret; |
3187 | |
3188 | if (nonoverlapping_memrefs_p (x, y: mem, loop_invariant: false)) |
3189 | return false; |
3190 | |
3191 | return rtx_refs_may_alias_p (x, mem, tbaa_p: false); |
3192 | } |
3193 | |
3194 | /* Anti dependence: X is written after read in MEM takes place. */ |
3195 | |
3196 | bool |
3197 | anti_dependence (const_rtx mem, const_rtx x) |
3198 | { |
3199 | return write_dependence_p (mem, x, VOIDmode, NULL_RTX, |
3200 | /*mem_canonicalized=*/false, |
3201 | /*x_canonicalized*/false, /*writep=*/false); |
3202 | } |
3203 | |
3204 | /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X. |
3205 | Also, consider X in X_MODE (which might be from an enclosing |
3206 | STRICT_LOW_PART / ZERO_EXTRACT). |
3207 | If MEM_CANONICALIZED is true, MEM is canonicalized. */ |
3208 | |
3209 | bool |
3210 | canon_anti_dependence (const_rtx mem, bool mem_canonicalized, |
3211 | const_rtx x, machine_mode x_mode, rtx x_addr) |
3212 | { |
3213 | return write_dependence_p (mem, x, x_mode, x_addr, |
3214 | mem_canonicalized, /*x_canonicalized=*/true, |
3215 | /*writep=*/false); |
3216 | } |
3217 | |
3218 | /* Output dependence: X is written after store in MEM takes place. */ |
3219 | |
3220 | bool |
3221 | output_dependence (const_rtx mem, const_rtx x) |
3222 | { |
3223 | return write_dependence_p (mem, x, VOIDmode, NULL_RTX, |
3224 | /*mem_canonicalized=*/false, |
3225 | /*x_canonicalized*/false, /*writep=*/true); |
3226 | } |
3227 | |
3228 | /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X. |
3229 | Also, consider X in X_MODE (which might be from an enclosing |
3230 | STRICT_LOW_PART / ZERO_EXTRACT). |
3231 | If MEM_CANONICALIZED is true, MEM is canonicalized. */ |
3232 | |
3233 | bool |
3234 | canon_output_dependence (const_rtx mem, bool mem_canonicalized, |
3235 | const_rtx x, machine_mode x_mode, rtx x_addr) |
3236 | { |
3237 | return write_dependence_p (mem, x, x_mode, x_addr, |
3238 | mem_canonicalized, /*x_canonicalized=*/true, |
3239 | /*writep=*/true); |
3240 | } |
3241 | |
3242 | |
3243 | |
3244 | /* Check whether X may be aliased with MEM. Don't do offset-based |
3245 | memory disambiguation & TBAA. */ |
3246 | bool |
3247 | may_alias_p (const_rtx mem, const_rtx x) |
3248 | { |
3249 | rtx x_addr, mem_addr; |
3250 | |
3251 | if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) |
3252 | return true; |
3253 | |
3254 | /* (mem:BLK (scratch)) is a special mechanism to conflict with everything. |
3255 | This is used in epilogue deallocation functions. */ |
3256 | if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH) |
3257 | return true; |
3258 | if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH) |
3259 | return true; |
3260 | if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER |
3261 | || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) |
3262 | return true; |
3263 | |
3264 | x_addr = XEXP (x, 0); |
3265 | x_addr = get_addr (x: x_addr); |
3266 | |
3267 | mem_addr = XEXP (mem, 0); |
3268 | mem_addr = get_addr (x: mem_addr); |
3269 | |
3270 | /* Read-only memory is by definition never modified, and therefore can't |
3271 | conflict with anything. However, don't assume anything when AND |
3272 | addresses are involved and leave to the code below to determine |
3273 | dependence. We don't expect to find read-only set on MEM, but |
3274 | stupid user tricks can produce them, so don't die. */ |
3275 | if (MEM_READONLY_P (x) |
3276 | && GET_CODE (x_addr) != AND |
3277 | && GET_CODE (mem_addr) != AND) |
3278 | return false; |
3279 | |
3280 | /* If we have MEMs referring to different address spaces (which can |
3281 | potentially overlap), we cannot easily tell from the addresses |
3282 | whether the references overlap. */ |
3283 | if (MEM_ADDR_SPACE (mem) != MEM_ADDR_SPACE (x)) |
3284 | return true; |
3285 | |
3286 | rtx x_base = find_base_term (x: x_addr); |
3287 | rtx mem_base = find_base_term (x: mem_addr); |
3288 | if (! base_alias_check (x: x_addr, x_base, y: mem_addr, y_base: mem_base, |
3289 | GET_MODE (x), GET_MODE (mem_addr))) |
3290 | return false; |
3291 | |
3292 | if (nonoverlapping_memrefs_p (x: mem, y: x, loop_invariant: true)) |
3293 | return false; |
3294 | |
3295 | /* TBAA not valid for loop_invarint */ |
3296 | return rtx_refs_may_alias_p (x, mem, tbaa_p: false); |
3297 | } |
3298 | |
3299 | void |
3300 | init_alias_target (void) |
3301 | { |
3302 | int i; |
3303 | |
3304 | if (!arg_base_value) |
3305 | arg_base_value = gen_rtx_ADDRESS (VOIDmode, 0); |
3306 | |
3307 | memset (static_reg_base_value, c: 0, n: sizeof static_reg_base_value); |
3308 | |
3309 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) |
3310 | /* Check whether this register can hold an incoming pointer |
3311 | argument. FUNCTION_ARG_REGNO_P tests outgoing register |
3312 | numbers, so translate if necessary due to register windows. */ |
3313 | if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i)) |
3314 | && targetm.hard_regno_mode_ok (i, Pmode)) |
3315 | static_reg_base_value[i] = arg_base_value; |
3316 | |
3317 | /* RTL code is required to be consistent about whether it uses the |
3318 | stack pointer, the frame pointer or the argument pointer to |
3319 | access a given area of the frame. We can therefore use the |
3320 | base address to distinguish between the different areas. */ |
3321 | static_reg_base_value[STACK_POINTER_REGNUM] |
3322 | = unique_base_value (UNIQUE_BASE_VALUE_SP); |
3323 | static_reg_base_value[ARG_POINTER_REGNUM] |
3324 | = unique_base_value (UNIQUE_BASE_VALUE_ARGP); |
3325 | static_reg_base_value[FRAME_POINTER_REGNUM] |
3326 | = unique_base_value (UNIQUE_BASE_VALUE_FP); |
3327 | |
3328 | /* The above rules extend post-reload, with eliminations applying |
3329 | consistently to each of the three pointers. Cope with cases in |
3330 | which the frame pointer is eliminated to the hard frame pointer |
3331 | rather than the stack pointer. */ |
3332 | if (!HARD_FRAME_POINTER_IS_FRAME_POINTER) |
3333 | static_reg_base_value[HARD_FRAME_POINTER_REGNUM] |
3334 | = unique_base_value (UNIQUE_BASE_VALUE_HFP); |
3335 | } |
3336 | |
3337 | /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed |
3338 | to be memory reference. */ |
3339 | static bool memory_modified; |
3340 | static void |
3341 | memory_modified_1 (rtx x, const_rtx pat ATTRIBUTE_UNUSED, void *data) |
3342 | { |
3343 | if (MEM_P (x)) |
3344 | { |
3345 | if (anti_dependence (mem: x, x: (const_rtx)data) || output_dependence (mem: x, x: (const_rtx)data)) |
3346 | memory_modified = true; |
3347 | } |
3348 | } |
3349 | |
3350 | |
3351 | /* Return true when INSN possibly modify memory contents of MEM |
3352 | (i.e. address can be modified). */ |
3353 | bool |
3354 | memory_modified_in_insn_p (const_rtx mem, const_rtx insn) |
3355 | { |
3356 | if (!INSN_P (insn)) |
3357 | return false; |
3358 | /* Conservatively assume all non-readonly MEMs might be modified in |
3359 | calls. */ |
3360 | if (CALL_P (insn)) |
3361 | return true; |
3362 | memory_modified = false; |
3363 | note_stores (as_a<const rtx_insn *> (p: insn), memory_modified_1, |
3364 | CONST_CAST_RTX(mem)); |
3365 | return memory_modified; |
3366 | } |
3367 | |
3368 | /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE |
3369 | array. */ |
3370 | |
3371 | void |
3372 | init_alias_analysis (void) |
3373 | { |
3374 | const bool frame_pointer_eliminated |
3375 | = reload_completed |
3376 | && !frame_pointer_needed |
3377 | && targetm.can_eliminate (FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM); |
3378 | unsigned int maxreg = max_reg_num (); |
3379 | bool changed; |
3380 | int pass, i; |
3381 | unsigned int ui; |
3382 | rtx_insn *insn; |
3383 | rtx val; |
3384 | int rpo_cnt; |
3385 | int *rpo; |
3386 | |
3387 | timevar_push (tv: TV_ALIAS_ANALYSIS); |
3388 | |
3389 | vec_safe_grow_cleared (v&: reg_known_value, len: maxreg - FIRST_PSEUDO_REGISTER, |
3390 | exact: true); |
3391 | reg_known_equiv_p = sbitmap_alloc (maxreg - FIRST_PSEUDO_REGISTER); |
3392 | bitmap_clear (reg_known_equiv_p); |
3393 | |
3394 | /* If we have memory allocated from the previous run, use it. */ |
3395 | if (old_reg_base_value) |
3396 | reg_base_value = old_reg_base_value; |
3397 | |
3398 | if (reg_base_value) |
3399 | reg_base_value->truncate (size: 0); |
3400 | |
3401 | vec_safe_grow_cleared (v&: reg_base_value, len: maxreg, exact: true); |
3402 | |
3403 | new_reg_base_value = XNEWVEC (rtx, maxreg); |
3404 | reg_seen = sbitmap_alloc (maxreg); |
3405 | |
3406 | /* The basic idea is that each pass through this loop will use the |
3407 | "constant" information from the previous pass to propagate alias |
3408 | information through another level of assignments. |
3409 | |
3410 | The propagation is done on the CFG in reverse post-order, to propagate |
3411 | things forward as far as possible in each iteration. |
3412 | |
3413 | This could get expensive if the assignment chains are long. Maybe |
3414 | we should throttle the number of iterations, possibly based on |
3415 | the optimization level or flag_expensive_optimizations. |
3416 | |
3417 | We could propagate more information in the first pass by making use |
3418 | of DF_REG_DEF_COUNT to determine immediately that the alias information |
3419 | for a pseudo is "constant". |
3420 | |
3421 | A program with an uninitialized variable can cause an infinite loop |
3422 | here. Instead of doing a full dataflow analysis to detect such problems |
3423 | we just cap the number of iterations for the loop. |
3424 | |
3425 | The state of the arrays for the set chain in question does not matter |
3426 | since the program has undefined behavior. */ |
3427 | |
3428 | rpo = XNEWVEC (int, n_basic_blocks_for_fn (cfun)); |
3429 | rpo_cnt = pre_and_rev_post_order_compute (NULL, rpo, false); |
3430 | |
3431 | pass = 0; |
3432 | do |
3433 | { |
3434 | /* Assume nothing will change this iteration of the loop. */ |
3435 | changed = false; |
3436 | |
3437 | /* We want to assign the same IDs each iteration of this loop, so |
3438 | start counting from one each iteration of the loop. */ |
3439 | unique_id = 1; |
3440 | |
3441 | /* We're at the start of the function each iteration through the |
3442 | loop, so we're copying arguments. */ |
3443 | copying_arguments = true; |
3444 | |
3445 | /* Wipe the potential alias information clean for this pass. */ |
3446 | memset (s: new_reg_base_value, c: 0, n: maxreg * sizeof (rtx)); |
3447 | |
3448 | /* Wipe the reg_seen array clean. */ |
3449 | bitmap_clear (reg_seen); |
3450 | |
3451 | /* Initialize the alias information for this pass. */ |
3452 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) |
3453 | if (static_reg_base_value[i] |
3454 | /* Don't treat the hard frame pointer as special if we |
3455 | eliminated the frame pointer to the stack pointer. */ |
3456 | && !(i == HARD_FRAME_POINTER_REGNUM && frame_pointer_eliminated)) |
3457 | { |
3458 | new_reg_base_value[i] = static_reg_base_value[i]; |
3459 | bitmap_set_bit (map: reg_seen, bitno: i); |
3460 | } |
3461 | |
3462 | /* Walk the insns adding values to the new_reg_base_value array. */ |
3463 | for (i = 0; i < rpo_cnt; i++) |
3464 | { |
3465 | basic_block bb = BASIC_BLOCK_FOR_FN (cfun, rpo[i]); |
3466 | FOR_BB_INSNS (bb, insn) |
3467 | { |
3468 | if (NONDEBUG_INSN_P (insn)) |
3469 | { |
3470 | rtx note, set; |
3471 | |
3472 | /* Treat the hard frame pointer as special unless we |
3473 | eliminated the frame pointer to the stack pointer. */ |
3474 | if (!frame_pointer_eliminated |
3475 | && modified_in_p (hard_frame_pointer_rtx, insn)) |
3476 | continue; |
3477 | |
3478 | /* If this insn has a noalias note, process it, Otherwise, |
3479 | scan for sets. A simple set will have no side effects |
3480 | which could change the base value of any other register. */ |
3481 | if (GET_CODE (PATTERN (insn)) == SET |
3482 | && REG_NOTES (insn) != 0 |
3483 | && find_reg_note (insn, REG_NOALIAS, NULL_RTX)) |
3484 | record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL); |
3485 | else |
3486 | note_stores (insn, record_set, NULL); |
3487 | |
3488 | set = single_set (insn); |
3489 | |
3490 | if (set != 0 |
3491 | && REG_P (SET_DEST (set)) |
3492 | && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER) |
3493 | { |
3494 | unsigned int regno = REGNO (SET_DEST (set)); |
3495 | rtx src = SET_SRC (set); |
3496 | rtx t; |
3497 | |
3498 | note = find_reg_equal_equiv_note (insn); |
3499 | if (note && REG_NOTE_KIND (note) == REG_EQUAL |
3500 | && DF_REG_DEF_COUNT (regno) != 1) |
3501 | note = NULL_RTX; |
3502 | |
3503 | poly_int64 offset; |
3504 | if (note != NULL_RTX |
3505 | && GET_CODE (XEXP (note, 0)) != EXPR_LIST |
3506 | && ! rtx_varies_p (XEXP (note, 0), 1) |
3507 | && ! reg_overlap_mentioned_p (SET_DEST (set), |
3508 | XEXP (note, 0))) |
3509 | { |
3510 | set_reg_known_value (regno, XEXP (note, 0)); |
3511 | set_reg_known_equiv_p (regno, |
3512 | REG_NOTE_KIND (note) == REG_EQUIV); |
3513 | } |
3514 | else if (DF_REG_DEF_COUNT (regno) == 1 |
3515 | && GET_CODE (src) == PLUS |
3516 | && REG_P (XEXP (src, 0)) |
3517 | && (t = get_reg_known_value (REGNO (XEXP (src, 0)))) |
3518 | && poly_int_rtx_p (XEXP (src, 1), res: &offset)) |
3519 | { |
3520 | t = plus_constant (GET_MODE (src), t, offset); |
3521 | set_reg_known_value (regno, val: t); |
3522 | set_reg_known_equiv_p (regno, val: false); |
3523 | } |
3524 | else if (DF_REG_DEF_COUNT (regno) == 1 |
3525 | && ! rtx_varies_p (src, 1)) |
3526 | { |
3527 | set_reg_known_value (regno, val: src); |
3528 | set_reg_known_equiv_p (regno, val: false); |
3529 | } |
3530 | } |
3531 | } |
3532 | else if (NOTE_P (insn) |
3533 | && NOTE_KIND (insn) == NOTE_INSN_FUNCTION_BEG) |
3534 | copying_arguments = false; |
3535 | } |
3536 | } |
3537 | |
3538 | /* Now propagate values from new_reg_base_value to reg_base_value. */ |
3539 | gcc_assert (maxreg == (unsigned int) max_reg_num ()); |
3540 | |
3541 | for (ui = 0; ui < maxreg; ui++) |
3542 | { |
3543 | if (new_reg_base_value[ui] |
3544 | && new_reg_base_value[ui] != (*reg_base_value)[ui] |
3545 | && ! rtx_equal_p (new_reg_base_value[ui], (*reg_base_value)[ui])) |
3546 | { |
3547 | (*reg_base_value)[ui] = new_reg_base_value[ui]; |
3548 | changed = true; |
3549 | } |
3550 | } |
3551 | } |
3552 | while (changed && ++pass < MAX_ALIAS_LOOP_PASSES); |
3553 | XDELETEVEC (rpo); |
3554 | |
3555 | /* Fill in the remaining entries. */ |
3556 | FOR_EACH_VEC_ELT (*reg_known_value, i, val) |
3557 | { |
3558 | int regno = i + FIRST_PSEUDO_REGISTER; |
3559 | if (! val) |
3560 | set_reg_known_value (regno, val: regno_reg_rtx[regno]); |
3561 | } |
3562 | |
3563 | /* Clean up. */ |
3564 | free (ptr: new_reg_base_value); |
3565 | new_reg_base_value = 0; |
3566 | sbitmap_free (map: reg_seen); |
3567 | reg_seen = 0; |
3568 | timevar_pop (tv: TV_ALIAS_ANALYSIS); |
3569 | } |
3570 | |
3571 | /* Equate REG_BASE_VALUE (reg1) to REG_BASE_VALUE (reg2). |
3572 | Special API for var-tracking pass purposes. */ |
3573 | |
3574 | void |
3575 | vt_equate_reg_base_value (const_rtx reg1, const_rtx reg2) |
3576 | { |
3577 | (*reg_base_value)[REGNO (reg1)] = REG_BASE_VALUE (reg2); |
3578 | } |
3579 | |
3580 | void |
3581 | end_alias_analysis (void) |
3582 | { |
3583 | old_reg_base_value = reg_base_value; |
3584 | vec_free (v&: reg_known_value); |
3585 | sbitmap_free (map: reg_known_equiv_p); |
3586 | } |
3587 | |
3588 | void |
3589 | dump_alias_stats_in_alias_c (FILE *s) |
3590 | { |
3591 | fprintf (stream: s, format: " TBAA oracle: %llu disambiguations %llu queries\n" |
3592 | " %llu are in alias set 0\n" |
3593 | " %llu queries asked about the same object\n" |
3594 | " %llu queries asked about the same alias set\n" |
3595 | " %llu access volatile\n" |
3596 | " %llu are dependent in the DAG\n" |
3597 | " %llu are aritificially in conflict with void *\n" , |
3598 | alias_stats.num_disambiguated, |
3599 | alias_stats.num_alias_zero + alias_stats.num_same_alias_set |
3600 | + alias_stats.num_same_objects + alias_stats.num_volatile |
3601 | + alias_stats.num_dag + alias_stats.num_disambiguated |
3602 | + alias_stats.num_universal, |
3603 | alias_stats.num_alias_zero, alias_stats.num_same_alias_set, |
3604 | alias_stats.num_same_objects, alias_stats.num_volatile, |
3605 | alias_stats.num_dag, alias_stats.num_universal); |
3606 | } |
3607 | #include "gt-alias.h" |
3608 | |