]>
Commit | Line | Data |
---|---|---|
9ae8ffe7 | 1 | /* Alias analysis for GNU C |
6e24b709 | 2 | Copyright (C) 1997, 1998, 1999, 2000, 2001 Free Software Foundation, Inc. |
9ae8ffe7 JL |
3 | Contributed by John Carr (jfc@mit.edu). |
4 | ||
5 | This file is part of GNU CC. | |
6 | ||
7 | GNU CC is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2, or (at your option) | |
10 | any later version. | |
11 | ||
12 | GNU CC is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GNU CC; see the file COPYING. If not, write to | |
19 | the Free Software Foundation, 59 Temple Place - Suite 330, | |
20 | Boston, MA 02111-1307, USA. */ | |
21 | ||
22 | #include "config.h" | |
670ee920 | 23 | #include "system.h" |
9ae8ffe7 | 24 | #include "rtl.h" |
7790df19 | 25 | #include "tree.h" |
6baf1cc8 | 26 | #include "tm_p.h" |
49ad7cfa | 27 | #include "function.h" |
9ae8ffe7 JL |
28 | #include "expr.h" |
29 | #include "regs.h" | |
30 | #include "hard-reg-set.h" | |
e004f2f7 | 31 | #include "basic-block.h" |
9ae8ffe7 | 32 | #include "flags.h" |
264fac34 | 33 | #include "output.h" |
2e107e9e | 34 | #include "toplev.h" |
eab5c70a | 35 | #include "cselib.h" |
3932261a | 36 | #include "splay-tree.h" |
ac606739 | 37 | #include "ggc.h" |
3932261a MM |
38 | |
39 | /* The alias sets assigned to MEMs assist the back-end in determining | |
40 | which MEMs can alias which other MEMs. In general, two MEMs in | |
ac3d9668 RK |
41 | different alias sets cannot alias each other, with one important |
42 | exception. Consider something like: | |
3932261a MM |
43 | |
44 | struct S {int i; double d; }; | |
45 | ||
46 | a store to an `S' can alias something of either type `int' or type | |
47 | `double'. (However, a store to an `int' cannot alias a `double' | |
48 | and vice versa.) We indicate this via a tree structure that looks | |
49 | like: | |
50 | struct S | |
51 | / \ | |
52 | / \ | |
53 | |/_ _\| | |
54 | int double | |
55 | ||
ac3d9668 RK |
56 | (The arrows are directed and point downwards.) |
57 | In this situation we say the alias set for `struct S' is the | |
58 | `superset' and that those for `int' and `double' are `subsets'. | |
59 | ||
3bdf5ad1 RK |
60 | To see whether two alias sets can point to the same memory, we must |
61 | see if either alias set is a subset of the other. We need not trace | |
62 | past immediate decendents, however, since we propagate all | |
63 | grandchildren up one level. | |
3932261a MM |
64 | |
65 | Alias set zero is implicitly a superset of all other alias sets. | |
66 | However, this is no actual entry for alias set zero. It is an | |
67 | error to attempt to explicitly construct a subset of zero. */ | |
68 | ||
d4b60170 RK |
69 | typedef struct alias_set_entry |
70 | { | |
3932261a | 71 | /* The alias set number, as stored in MEM_ALIAS_SET. */ |
3bdf5ad1 | 72 | HOST_WIDE_INT alias_set; |
3932261a MM |
73 | |
74 | /* The children of the alias set. These are not just the immediate | |
ac3d9668 | 75 | children, but, in fact, all decendents. So, if we have: |
3932261a MM |
76 | |
77 | struct T { struct S s; float f; } | |
78 | ||
79 | continuing our example above, the children here will be all of | |
80 | `int', `double', `float', and `struct S'. */ | |
81 | splay_tree children; | |
2bf105ab RK |
82 | |
83 | /* Nonzero if would have a child of zero: this effectively makes this | |
84 | alias set the same as alias set zero. */ | |
85 | int has_zero_child; | |
d4b60170 | 86 | } *alias_set_entry; |
9ae8ffe7 | 87 | |
3d994c6b KG |
88 | static int rtx_equal_for_memref_p PARAMS ((rtx, rtx)); |
89 | static rtx find_symbolic_term PARAMS ((rtx)); | |
a13d4ebf | 90 | rtx get_addr PARAMS ((rtx)); |
3d994c6b KG |
91 | static int memrefs_conflict_p PARAMS ((int, rtx, int, rtx, |
92 | HOST_WIDE_INT)); | |
93 | static void record_set PARAMS ((rtx, rtx, void *)); | |
94 | static rtx find_base_term PARAMS ((rtx)); | |
95 | static int base_alias_check PARAMS ((rtx, rtx, enum machine_mode, | |
96 | enum machine_mode)); | |
6e24b709 RK |
97 | static int handled_component_p PARAMS ((tree)); |
98 | static int can_address_p PARAMS ((tree)); | |
3d994c6b KG |
99 | static rtx find_base_value PARAMS ((rtx)); |
100 | static int mems_in_disjoint_alias_sets_p PARAMS ((rtx, rtx)); | |
101 | static int insert_subset_children PARAMS ((splay_tree_node, void*)); | |
3bdf5ad1 RK |
102 | static tree find_base_decl PARAMS ((tree)); |
103 | static alias_set_entry get_alias_set_entry PARAMS ((HOST_WIDE_INT)); | |
eab5c70a | 104 | static rtx fixed_scalar_and_varying_struct_p PARAMS ((rtx, rtx, rtx, rtx, |
e38fe8e0 | 105 | int (*) (rtx, int))); |
3d994c6b KG |
106 | static int aliases_everything_p PARAMS ((rtx)); |
107 | static int write_dependence_p PARAMS ((rtx, rtx, int)); | |
bf6d9fd7 | 108 | static int nonlocal_mentioned_p PARAMS ((rtx)); |
9ae8ffe7 | 109 | |
e004f2f7 JW |
110 | static int loop_p PARAMS ((void)); |
111 | ||
9ae8ffe7 JL |
112 | /* Set up all info needed to perform alias analysis on memory references. */ |
113 | ||
d4b60170 | 114 | /* Returns the size in bytes of the mode of X. */ |
9ae8ffe7 JL |
115 | #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X))) |
116 | ||
41472af8 | 117 | /* Returns nonzero if MEM1 and MEM2 do not alias because they are in |
264fac34 MM |
118 | different alias sets. We ignore alias sets in functions making use |
119 | of variable arguments because the va_arg macros on some systems are | |
120 | not legal ANSI C. */ | |
121 | #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \ | |
3932261a | 122 | mems_in_disjoint_alias_sets_p (MEM1, MEM2) |
41472af8 | 123 | |
ea64ef27 | 124 | /* Cap the number of passes we make over the insns propagating alias |
ac3d9668 | 125 | information through set chains. 10 is a completely arbitrary choice. */ |
ea64ef27 JL |
126 | #define MAX_ALIAS_LOOP_PASSES 10 |
127 | ||
9ae8ffe7 JL |
128 | /* reg_base_value[N] gives an address to which register N is related. |
129 | If all sets after the first add or subtract to the current value | |
130 | or otherwise modify it so it does not point to a different top level | |
131 | object, reg_base_value[N] is equal to the address part of the source | |
2a2c8203 JC |
132 | of the first set. |
133 | ||
134 | A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS | |
135 | expressions represent certain special values: function arguments and | |
b3b5ad95 JL |
136 | the stack, frame, and argument pointers. |
137 | ||
138 | The contents of an ADDRESS is not normally used, the mode of the | |
139 | ADDRESS determines whether the ADDRESS is a function argument or some | |
140 | other special value. Pointer equality, not rtx_equal_p, determines whether | |
141 | two ADDRESS expressions refer to the same base address. | |
142 | ||
143 | The only use of the contents of an ADDRESS is for determining if the | |
144 | current function performs nonlocal memory memory references for the | |
145 | purposes of marking the function as a constant function. */ | |
2a2c8203 | 146 | |
ac606739 GS |
147 | static rtx *reg_base_value; |
148 | static rtx *new_reg_base_value; | |
d4b60170 RK |
149 | static unsigned int reg_base_value_size; /* size of reg_base_value array */ |
150 | ||
9ae8ffe7 | 151 | #define REG_BASE_VALUE(X) \ |
fb6754f0 BS |
152 | (REGNO (X) < reg_base_value_size \ |
153 | ? reg_base_value[REGNO (X)] : 0) | |
9ae8ffe7 | 154 | |
de12be17 JC |
155 | /* Vector of known invariant relationships between registers. Set in |
156 | loop unrolling. Indexed by register number, if nonzero the value | |
157 | is an expression describing this register in terms of another. | |
158 | ||
159 | The length of this array is REG_BASE_VALUE_SIZE. | |
160 | ||
161 | Because this array contains only pseudo registers it has no effect | |
162 | after reload. */ | |
163 | static rtx *alias_invariant; | |
164 | ||
c13e8210 MM |
165 | /* Vector indexed by N giving the initial (unchanging) value known for |
166 | pseudo-register N. This array is initialized in | |
167 | init_alias_analysis, and does not change until end_alias_analysis | |
168 | is called. */ | |
9ae8ffe7 JL |
169 | rtx *reg_known_value; |
170 | ||
171 | /* Indicates number of valid entries in reg_known_value. */ | |
770ae6cc | 172 | static unsigned int reg_known_value_size; |
9ae8ffe7 JL |
173 | |
174 | /* Vector recording for each reg_known_value whether it is due to a | |
175 | REG_EQUIV note. Future passes (viz., reload) may replace the | |
176 | pseudo with the equivalent expression and so we account for the | |
ac3d9668 RK |
177 | dependences that would be introduced if that happens. |
178 | ||
179 | The REG_EQUIV notes created in assign_parms may mention the arg | |
180 | pointer, and there are explicit insns in the RTL that modify the | |
181 | arg pointer. Thus we must ensure that such insns don't get | |
182 | scheduled across each other because that would invalidate the | |
183 | REG_EQUIV notes. One could argue that the REG_EQUIV notes are | |
184 | wrong, but solving the problem in the scheduler will likely give | |
185 | better code, so we do it here. */ | |
9ae8ffe7 JL |
186 | char *reg_known_equiv_p; |
187 | ||
2a2c8203 JC |
188 | /* True when scanning insns from the start of the rtl to the |
189 | NOTE_INSN_FUNCTION_BEG note. */ | |
9ae8ffe7 JL |
190 | static int copying_arguments; |
191 | ||
3932261a | 192 | /* The splay-tree used to store the various alias set entries. */ |
3932261a | 193 | static splay_tree alias_sets; |
ac3d9668 | 194 | \f |
3932261a MM |
195 | /* Returns a pointer to the alias set entry for ALIAS_SET, if there is |
196 | such an entry, or NULL otherwise. */ | |
197 | ||
198 | static alias_set_entry | |
199 | get_alias_set_entry (alias_set) | |
3bdf5ad1 | 200 | HOST_WIDE_INT alias_set; |
3932261a | 201 | { |
d4b60170 RK |
202 | splay_tree_node sn |
203 | = splay_tree_lookup (alias_sets, (splay_tree_key) alias_set); | |
3932261a | 204 | |
d4b60170 | 205 | return sn != 0 ? ((alias_set_entry) sn->value) : 0; |
3932261a MM |
206 | } |
207 | ||
ac3d9668 RK |
208 | /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that |
209 | the two MEMs cannot alias each other. */ | |
3932261a MM |
210 | |
211 | static int | |
212 | mems_in_disjoint_alias_sets_p (mem1, mem2) | |
213 | rtx mem1; | |
214 | rtx mem2; | |
215 | { | |
3932261a MM |
216 | #ifdef ENABLE_CHECKING |
217 | /* Perform a basic sanity check. Namely, that there are no alias sets | |
218 | if we're not using strict aliasing. This helps to catch bugs | |
219 | whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or | |
220 | where a MEM is allocated in some way other than by the use of | |
221 | gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to | |
222 | use alias sets to indicate that spilled registers cannot alias each | |
223 | other, we might need to remove this check. */ | |
d4b60170 RK |
224 | if (! flag_strict_aliasing |
225 | && (MEM_ALIAS_SET (mem1) != 0 || MEM_ALIAS_SET (mem2) != 0)) | |
3932261a MM |
226 | abort (); |
227 | #endif | |
228 | ||
1da68f56 RK |
229 | return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1), MEM_ALIAS_SET (mem2)); |
230 | } | |
3932261a | 231 | |
1da68f56 RK |
232 | /* Insert the NODE into the splay tree given by DATA. Used by |
233 | record_alias_subset via splay_tree_foreach. */ | |
234 | ||
235 | static int | |
236 | insert_subset_children (node, data) | |
237 | splay_tree_node node; | |
238 | void *data; | |
239 | { | |
240 | splay_tree_insert ((splay_tree) data, node->key, node->value); | |
241 | ||
242 | return 0; | |
243 | } | |
244 | ||
245 | /* Return 1 if the two specified alias sets may conflict. */ | |
246 | ||
247 | int | |
248 | alias_sets_conflict_p (set1, set2) | |
249 | HOST_WIDE_INT set1, set2; | |
250 | { | |
251 | alias_set_entry ase; | |
252 | ||
253 | /* If have no alias set information for one of the operands, we have | |
254 | to assume it can alias anything. */ | |
255 | if (set1 == 0 || set2 == 0 | |
256 | /* If the two alias sets are the same, they may alias. */ | |
257 | || set1 == set2) | |
258 | return 1; | |
3932261a | 259 | |
3bdf5ad1 | 260 | /* See if the first alias set is a subset of the second. */ |
1da68f56 | 261 | ase = get_alias_set_entry (set1); |
2bf105ab RK |
262 | if (ase != 0 |
263 | && (ase->has_zero_child | |
264 | || splay_tree_lookup (ase->children, | |
1da68f56 RK |
265 | (splay_tree_key) set2))) |
266 | return 1; | |
3932261a MM |
267 | |
268 | /* Now do the same, but with the alias sets reversed. */ | |
1da68f56 | 269 | ase = get_alias_set_entry (set2); |
2bf105ab RK |
270 | if (ase != 0 |
271 | && (ase->has_zero_child | |
272 | || splay_tree_lookup (ase->children, | |
1da68f56 RK |
273 | (splay_tree_key) set1))) |
274 | return 1; | |
3932261a | 275 | |
1da68f56 | 276 | /* The two alias sets are distinct and neither one is the |
3932261a | 277 | child of the other. Therefore, they cannot alias. */ |
1da68f56 | 278 | return 0; |
3932261a | 279 | } |
1da68f56 | 280 | \f |
ba4828e0 RK |
281 | /* Set the alias set of MEM to SET. */ |
282 | ||
283 | void | |
284 | set_mem_alias_set (mem, set) | |
285 | rtx mem; | |
286 | HOST_WIDE_INT set; | |
287 | { | |
288 | /* We would like to do this test but can't yet since when converting a | |
289 | REG to a MEM, the alias set field is undefined. */ | |
290 | #if 0 | |
291 | /* If the new and old alias sets don't conflict, something is wrong. */ | |
292 | if (!alias_sets_conflict_p (set, MEM_ALIAS_SET (mem))) | |
293 | abort (); | |
294 | #endif | |
295 | ||
296 | MEM_ALIAS_SET (mem) = set; | |
297 | } | |
298 | \f | |
1da68f56 RK |
299 | /* Return 1 if TYPE is a RECORD_TYPE, UNION_TYPE, or QUAL_UNION_TYPE and has |
300 | has any readonly fields. If any of the fields have types that | |
301 | contain readonly fields, return true as well. */ | |
3932261a | 302 | |
1da68f56 RK |
303 | int |
304 | readonly_fields_p (type) | |
305 | tree type; | |
3932261a | 306 | { |
1da68f56 RK |
307 | tree field; |
308 | ||
309 | if (TREE_CODE (type) != RECORD_TYPE && TREE_CODE (type) != UNION_TYPE | |
310 | && TREE_CODE (type) != QUAL_UNION_TYPE) | |
311 | return 0; | |
312 | ||
313 | for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field)) | |
314 | if (TREE_CODE (field) == FIELD_DECL | |
315 | && (TREE_READONLY (field) | |
316 | || readonly_fields_p (TREE_TYPE (field)))) | |
317 | return 1; | |
3932261a MM |
318 | |
319 | return 0; | |
320 | } | |
3bdf5ad1 | 321 | \f |
1da68f56 RK |
322 | /* Return 1 if any MEM object of type T1 will always conflict (using the |
323 | dependency routines in this file) with any MEM object of type T2. | |
324 | This is used when allocating temporary storage. If T1 and/or T2 are | |
325 | NULL_TREE, it means we know nothing about the storage. */ | |
326 | ||
327 | int | |
328 | objects_must_conflict_p (t1, t2) | |
329 | tree t1, t2; | |
330 | { | |
e8ea2809 RK |
331 | /* If neither has a type specified, we don't know if they'll conflict |
332 | because we may be using them to store objects of various types, for | |
333 | example the argument and local variables areas of inlined functions. */ | |
981a4c34 | 334 | if (t1 == 0 && t2 == 0) |
e8ea2809 RK |
335 | return 0; |
336 | ||
66cce54d RH |
337 | /* If one or the other has readonly fields or is readonly, |
338 | then they may not conflict. */ | |
339 | if ((t1 != 0 && readonly_fields_p (t1)) | |
340 | || (t2 != 0 && readonly_fields_p (t2)) | |
341 | || (t1 != 0 && TYPE_READONLY (t1)) | |
342 | || (t2 != 0 && TYPE_READONLY (t2))) | |
343 | return 0; | |
344 | ||
1da68f56 RK |
345 | /* If they are the same type, they must conflict. */ |
346 | if (t1 == t2 | |
347 | /* Likewise if both are volatile. */ | |
348 | || (t1 != 0 && TYPE_VOLATILE (t1) && t2 != 0 && TYPE_VOLATILE (t2))) | |
349 | return 1; | |
350 | ||
66cce54d RH |
351 | /* If one is aggregate and the other is scalar then they may not |
352 | conflict. */ | |
353 | if ((t1 != 0 && AGGREGATE_TYPE_P (t1)) | |
354 | != (t2 != 0 && AGGREGATE_TYPE_P (t2))) | |
1da68f56 RK |
355 | return 0; |
356 | ||
357 | /* Otherwise they conflict only if the alias sets conflict. */ | |
358 | return alias_sets_conflict_p (t1 ? get_alias_set (t1) : 0, | |
359 | t2 ? get_alias_set (t2) : 0); | |
360 | } | |
361 | \f | |
3bdf5ad1 RK |
362 | /* T is an expression with pointer type. Find the DECL on which this |
363 | expression is based. (For example, in `a[i]' this would be `a'.) | |
364 | If there is no such DECL, or a unique decl cannot be determined, | |
365 | NULL_TREE is retured. */ | |
366 | ||
367 | static tree | |
368 | find_base_decl (t) | |
369 | tree t; | |
370 | { | |
371 | tree d0, d1, d2; | |
372 | ||
373 | if (t == 0 || t == error_mark_node || ! POINTER_TYPE_P (TREE_TYPE (t))) | |
374 | return 0; | |
375 | ||
376 | /* If this is a declaration, return it. */ | |
377 | if (TREE_CODE_CLASS (TREE_CODE (t)) == 'd') | |
378 | return t; | |
379 | ||
380 | /* Handle general expressions. It would be nice to deal with | |
381 | COMPONENT_REFs here. If we could tell that `a' and `b' were the | |
382 | same, then `a->f' and `b->f' are also the same. */ | |
383 | switch (TREE_CODE_CLASS (TREE_CODE (t))) | |
384 | { | |
385 | case '1': | |
386 | return find_base_decl (TREE_OPERAND (t, 0)); | |
387 | ||
388 | case '2': | |
389 | /* Return 0 if found in neither or both are the same. */ | |
390 | d0 = find_base_decl (TREE_OPERAND (t, 0)); | |
391 | d1 = find_base_decl (TREE_OPERAND (t, 1)); | |
392 | if (d0 == d1) | |
393 | return d0; | |
394 | else if (d0 == 0) | |
395 | return d1; | |
396 | else if (d1 == 0) | |
397 | return d0; | |
398 | else | |
399 | return 0; | |
400 | ||
401 | case '3': | |
402 | d0 = find_base_decl (TREE_OPERAND (t, 0)); | |
403 | d1 = find_base_decl (TREE_OPERAND (t, 1)); | |
404 | d0 = find_base_decl (TREE_OPERAND (t, 0)); | |
405 | d2 = find_base_decl (TREE_OPERAND (t, 2)); | |
406 | ||
407 | /* Set any nonzero values from the last, then from the first. */ | |
408 | if (d1 == 0) d1 = d2; | |
409 | if (d0 == 0) d0 = d1; | |
410 | if (d1 == 0) d1 = d0; | |
411 | if (d2 == 0) d2 = d1; | |
412 | ||
413 | /* At this point all are nonzero or all are zero. If all three are the | |
414 | same, return it. Otherwise, return zero. */ | |
415 | return (d0 == d1 && d1 == d2) ? d0 : 0; | |
416 | ||
417 | default: | |
418 | return 0; | |
419 | } | |
420 | } | |
421 | ||
6e24b709 RK |
422 | /* Return 1 if T is an expression that get_inner_reference handles. */ |
423 | ||
424 | static int | |
425 | handled_component_p (t) | |
426 | tree t; | |
427 | { | |
428 | switch (TREE_CODE (t)) | |
429 | { | |
430 | case BIT_FIELD_REF: | |
431 | case COMPONENT_REF: | |
432 | case ARRAY_REF: | |
b4e3fabb | 433 | case ARRAY_RANGE_REF: |
6e24b709 RK |
434 | case NON_LVALUE_EXPR: |
435 | return 1; | |
436 | ||
437 | case NOP_EXPR: | |
438 | case CONVERT_EXPR: | |
439 | return (TYPE_MODE (TREE_TYPE (t)) | |
440 | == TYPE_MODE (TREE_TYPE (TREE_OPERAND (t, 0)))); | |
441 | ||
442 | default: | |
443 | return 0; | |
444 | } | |
445 | } | |
446 | ||
447 | /* Return 1 if all the nested component references handled by | |
448 | get_inner_reference in T are such that we can address the object in T. */ | |
449 | ||
450 | static int | |
451 | can_address_p (t) | |
452 | tree t; | |
453 | { | |
454 | /* If we're at the end, it is vacuously addressable. */ | |
455 | if (! handled_component_p (t)) | |
456 | return 1; | |
457 | ||
458 | /* Bitfields are never addressable. */ | |
459 | else if (TREE_CODE (t) == BIT_FIELD_REF) | |
460 | return 0; | |
461 | ||
462 | else if (TREE_CODE (t) == COMPONENT_REF | |
463 | && ! DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1)) | |
464 | && can_address_p (TREE_OPERAND (t, 0))) | |
465 | return 1; | |
466 | ||
b4e3fabb | 467 | else if ((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF) |
6e24b709 RK |
468 | && ! TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t, 0))) |
469 | && can_address_p (TREE_OPERAND (t, 0))) | |
470 | return 1; | |
471 | ||
472 | return 0; | |
473 | } | |
474 | ||
3bdf5ad1 RK |
475 | /* Return the alias set for T, which may be either a type or an |
476 | expression. Call language-specific routine for help, if needed. */ | |
477 | ||
478 | HOST_WIDE_INT | |
479 | get_alias_set (t) | |
480 | tree t; | |
481 | { | |
f824e5c3 | 482 | tree orig_t; |
3bdf5ad1 | 483 | HOST_WIDE_INT set; |
3bdf5ad1 RK |
484 | |
485 | /* If we're not doing any alias analysis, just assume everything | |
486 | aliases everything else. Also return 0 if this or its type is | |
487 | an error. */ | |
488 | if (! flag_strict_aliasing || t == error_mark_node | |
489 | || (! TYPE_P (t) | |
490 | && (TREE_TYPE (t) == 0 || TREE_TYPE (t) == error_mark_node))) | |
491 | return 0; | |
492 | ||
493 | /* We can be passed either an expression or a type. This and the | |
494 | language-specific routine may make mutually-recursive calls to | |
495 | each other to figure out what to do. At each juncture, we see if | |
496 | this is a tree that the language may need to handle specially. | |
f824e5c3 RK |
497 | First handle things that aren't types and start by removing nops |
498 | since we care only about the actual object. */ | |
499 | if (! TYPE_P (t)) | |
3bdf5ad1 | 500 | { |
f824e5c3 RK |
501 | while (TREE_CODE (t) == NOP_EXPR || TREE_CODE (t) == CONVERT_EXPR |
502 | || TREE_CODE (t) == NON_LVALUE_EXPR) | |
503 | t = TREE_OPERAND (t, 0); | |
504 | ||
505 | /* Now give the language a chance to do something but record what we | |
506 | gave it this time. */ | |
507 | orig_t = t; | |
2e761e49 | 508 | if ((set = lang_get_alias_set (t)) != -1) |
f824e5c3 RK |
509 | return set; |
510 | ||
80661759 RK |
511 | /* Now loop the same way as get_inner_reference and get the alias |
512 | set to use. Pick up the outermost object that we could have | |
513 | a pointer to. */ | |
6e24b709 RK |
514 | while (handled_component_p (t) && ! can_address_p (t)) |
515 | t = TREE_OPERAND (t, 0); | |
516 | ||
f824e5c3 RK |
517 | if (TREE_CODE (t) == INDIRECT_REF) |
518 | { | |
519 | /* Check for accesses through restrict-qualified pointers. */ | |
520 | tree decl = find_base_decl (TREE_OPERAND (t, 0)); | |
521 | ||
522 | if (decl && DECL_POINTER_ALIAS_SET_KNOWN_P (decl)) | |
523 | /* We use the alias set indicated in the declaration. */ | |
524 | return DECL_POINTER_ALIAS_SET (decl); | |
525 | ||
526 | /* If we have an INDIRECT_REF via a void pointer, we don't | |
527 | know anything about what that might alias. */ | |
528 | if (TREE_CODE (TREE_TYPE (t)) == VOID_TYPE) | |
529 | return 0; | |
530 | } | |
531 | ||
532 | /* Give the language another chance to do something special. */ | |
2e761e49 RH |
533 | if (orig_t != t |
534 | && (set = lang_get_alias_set (t)) != -1) | |
f824e5c3 RK |
535 | return set; |
536 | ||
537 | /* Now all we care about is the type. */ | |
538 | t = TREE_TYPE (t); | |
3bdf5ad1 RK |
539 | } |
540 | ||
3bdf5ad1 RK |
541 | /* Variant qualifiers don't affect the alias set, so get the main |
542 | variant. If this is a type with a known alias set, return it. */ | |
543 | t = TYPE_MAIN_VARIANT (t); | |
544 | if (TYPE_P (t) && TYPE_ALIAS_SET_KNOWN_P (t)) | |
545 | return TYPE_ALIAS_SET (t); | |
546 | ||
547 | /* See if the language has special handling for this type. */ | |
2e761e49 | 548 | if ((set = lang_get_alias_set (t)) != -1) |
2bf105ab RK |
549 | { |
550 | /* If the alias set is now known, we are done. */ | |
551 | if (TYPE_ALIAS_SET_KNOWN_P (t)) | |
552 | return TYPE_ALIAS_SET (t); | |
553 | } | |
554 | ||
3bdf5ad1 RK |
555 | /* There are no objects of FUNCTION_TYPE, so there's no point in |
556 | using up an alias set for them. (There are, of course, pointers | |
557 | and references to functions, but that's different.) */ | |
558 | else if (TREE_CODE (t) == FUNCTION_TYPE) | |
559 | set = 0; | |
560 | else | |
561 | /* Otherwise make a new alias set for this type. */ | |
562 | set = new_alias_set (); | |
563 | ||
564 | TYPE_ALIAS_SET (t) = set; | |
2bf105ab RK |
565 | |
566 | /* If this is an aggregate type, we must record any component aliasing | |
567 | information. */ | |
1d79fd2c | 568 | if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE) |
2bf105ab RK |
569 | record_component_aliases (t); |
570 | ||
3bdf5ad1 RK |
571 | return set; |
572 | } | |
573 | ||
574 | /* Return a brand-new alias set. */ | |
575 | ||
576 | HOST_WIDE_INT | |
577 | new_alias_set () | |
578 | { | |
579 | static HOST_WIDE_INT last_alias_set; | |
580 | ||
581 | if (flag_strict_aliasing) | |
582 | return ++last_alias_set; | |
583 | else | |
584 | return 0; | |
585 | } | |
3932261a MM |
586 | |
587 | /* Indicate that things in SUBSET can alias things in SUPERSET, but | |
588 | not vice versa. For example, in C, a store to an `int' can alias a | |
589 | structure containing an `int', but not vice versa. Here, the | |
590 | structure would be the SUPERSET and `int' the SUBSET. This | |
a0c33338 | 591 | function should be called only once per SUPERSET/SUBSET pair. |
3932261a MM |
592 | |
593 | It is illegal for SUPERSET to be zero; everything is implicitly a | |
594 | subset of alias set zero. */ | |
595 | ||
596 | void | |
597 | record_alias_subset (superset, subset) | |
3bdf5ad1 RK |
598 | HOST_WIDE_INT superset; |
599 | HOST_WIDE_INT subset; | |
3932261a MM |
600 | { |
601 | alias_set_entry superset_entry; | |
602 | alias_set_entry subset_entry; | |
603 | ||
604 | if (superset == 0) | |
605 | abort (); | |
606 | ||
607 | superset_entry = get_alias_set_entry (superset); | |
d4b60170 | 608 | if (superset_entry == 0) |
3932261a MM |
609 | { |
610 | /* Create an entry for the SUPERSET, so that we have a place to | |
611 | attach the SUBSET. */ | |
d4b60170 RK |
612 | superset_entry |
613 | = (alias_set_entry) xmalloc (sizeof (struct alias_set_entry)); | |
3932261a MM |
614 | superset_entry->alias_set = superset; |
615 | superset_entry->children | |
30f72379 | 616 | = splay_tree_new (splay_tree_compare_ints, 0, 0); |
570eb5c8 | 617 | superset_entry->has_zero_child = 0; |
d4b60170 | 618 | splay_tree_insert (alias_sets, (splay_tree_key) superset, |
3932261a | 619 | (splay_tree_value) superset_entry); |
3932261a MM |
620 | } |
621 | ||
2bf105ab RK |
622 | if (subset == 0) |
623 | superset_entry->has_zero_child = 1; | |
624 | else | |
625 | { | |
626 | subset_entry = get_alias_set_entry (subset); | |
627 | /* If there is an entry for the subset, enter all of its children | |
628 | (if they are not already present) as children of the SUPERSET. */ | |
629 | if (subset_entry) | |
630 | { | |
631 | if (subset_entry->has_zero_child) | |
632 | superset_entry->has_zero_child = 1; | |
d4b60170 | 633 | |
2bf105ab RK |
634 | splay_tree_foreach (subset_entry->children, insert_subset_children, |
635 | superset_entry->children); | |
636 | } | |
3932261a | 637 | |
2bf105ab RK |
638 | /* Enter the SUBSET itself as a child of the SUPERSET. */ |
639 | splay_tree_insert (superset_entry->children, | |
640 | (splay_tree_key) subset, 0); | |
641 | } | |
3932261a MM |
642 | } |
643 | ||
a0c33338 RK |
644 | /* Record that component types of TYPE, if any, are part of that type for |
645 | aliasing purposes. For record types, we only record component types | |
646 | for fields that are marked addressable. For array types, we always | |
647 | record the component types, so the front end should not call this | |
648 | function if the individual component aren't addressable. */ | |
649 | ||
650 | void | |
651 | record_component_aliases (type) | |
652 | tree type; | |
653 | { | |
3bdf5ad1 | 654 | HOST_WIDE_INT superset = get_alias_set (type); |
a0c33338 RK |
655 | tree field; |
656 | ||
657 | if (superset == 0) | |
658 | return; | |
659 | ||
660 | switch (TREE_CODE (type)) | |
661 | { | |
662 | case ARRAY_TYPE: | |
2bf105ab RK |
663 | if (! TYPE_NONALIASED_COMPONENT (type)) |
664 | record_alias_subset (superset, get_alias_set (TREE_TYPE (type))); | |
a0c33338 RK |
665 | break; |
666 | ||
667 | case RECORD_TYPE: | |
668 | case UNION_TYPE: | |
669 | case QUAL_UNION_TYPE: | |
670 | for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field)) | |
b16a49a1 | 671 | if (TREE_CODE (field) == FIELD_DECL && ! DECL_NONADDRESSABLE_P (field)) |
2bf105ab | 672 | record_alias_subset (superset, get_alias_set (TREE_TYPE (field))); |
a0c33338 RK |
673 | break; |
674 | ||
1d79fd2c JW |
675 | case COMPLEX_TYPE: |
676 | record_alias_subset (superset, get_alias_set (TREE_TYPE (type))); | |
677 | break; | |
678 | ||
a0c33338 RK |
679 | default: |
680 | break; | |
681 | } | |
682 | } | |
683 | ||
3bdf5ad1 RK |
684 | /* Allocate an alias set for use in storing and reading from the varargs |
685 | spill area. */ | |
686 | ||
687 | HOST_WIDE_INT | |
688 | get_varargs_alias_set () | |
689 | { | |
690 | static HOST_WIDE_INT set = -1; | |
691 | ||
692 | if (set == -1) | |
693 | set = new_alias_set (); | |
694 | ||
695 | return set; | |
696 | } | |
697 | ||
698 | /* Likewise, but used for the fixed portions of the frame, e.g., register | |
699 | save areas. */ | |
700 | ||
701 | HOST_WIDE_INT | |
702 | get_frame_alias_set () | |
703 | { | |
704 | static HOST_WIDE_INT set = -1; | |
705 | ||
706 | if (set == -1) | |
707 | set = new_alias_set (); | |
708 | ||
709 | return set; | |
710 | } | |
711 | ||
2a2c8203 JC |
712 | /* Inside SRC, the source of a SET, find a base address. */ |
713 | ||
9ae8ffe7 JL |
714 | static rtx |
715 | find_base_value (src) | |
716 | register rtx src; | |
717 | { | |
713f41f9 | 718 | unsigned int regno; |
9ae8ffe7 JL |
719 | switch (GET_CODE (src)) |
720 | { | |
721 | case SYMBOL_REF: | |
722 | case LABEL_REF: | |
723 | return src; | |
724 | ||
725 | case REG: | |
fb6754f0 | 726 | regno = REGNO (src); |
d4b60170 | 727 | /* At the start of a function, argument registers have known base |
2a2c8203 JC |
728 | values which may be lost later. Returning an ADDRESS |
729 | expression here allows optimization based on argument values | |
730 | even when the argument registers are used for other purposes. */ | |
713f41f9 BS |
731 | if (regno < FIRST_PSEUDO_REGISTER && copying_arguments) |
732 | return new_reg_base_value[regno]; | |
73774bc7 | 733 | |
eaf407a5 JL |
734 | /* If a pseudo has a known base value, return it. Do not do this |
735 | for hard regs since it can result in a circular dependency | |
736 | chain for registers which have values at function entry. | |
737 | ||
738 | The test above is not sufficient because the scheduler may move | |
739 | a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */ | |
713f41f9 BS |
740 | if (regno >= FIRST_PSEUDO_REGISTER |
741 | && regno < reg_base_value_size | |
742 | && reg_base_value[regno]) | |
743 | return reg_base_value[regno]; | |
73774bc7 | 744 | |
9ae8ffe7 JL |
745 | return src; |
746 | ||
747 | case MEM: | |
748 | /* Check for an argument passed in memory. Only record in the | |
749 | copying-arguments block; it is too hard to track changes | |
750 | otherwise. */ | |
751 | if (copying_arguments | |
752 | && (XEXP (src, 0) == arg_pointer_rtx | |
753 | || (GET_CODE (XEXP (src, 0)) == PLUS | |
754 | && XEXP (XEXP (src, 0), 0) == arg_pointer_rtx))) | |
38a448ca | 755 | return gen_rtx_ADDRESS (VOIDmode, src); |
9ae8ffe7 JL |
756 | return 0; |
757 | ||
758 | case CONST: | |
759 | src = XEXP (src, 0); | |
760 | if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS) | |
761 | break; | |
d4b60170 RK |
762 | |
763 | /* ... fall through ... */ | |
2a2c8203 | 764 | |
9ae8ffe7 JL |
765 | case PLUS: |
766 | case MINUS: | |
2a2c8203 | 767 | { |
ec907dd8 JL |
768 | rtx temp, src_0 = XEXP (src, 0), src_1 = XEXP (src, 1); |
769 | ||
770 | /* If either operand is a REG, then see if we already have | |
771 | a known value for it. */ | |
772 | if (GET_CODE (src_0) == REG) | |
773 | { | |
774 | temp = find_base_value (src_0); | |
d4b60170 | 775 | if (temp != 0) |
ec907dd8 JL |
776 | src_0 = temp; |
777 | } | |
778 | ||
779 | if (GET_CODE (src_1) == REG) | |
780 | { | |
781 | temp = find_base_value (src_1); | |
d4b60170 | 782 | if (temp!= 0) |
ec907dd8 JL |
783 | src_1 = temp; |
784 | } | |
2a2c8203 | 785 | |
d4b60170 | 786 | /* Guess which operand is the base address: |
ec907dd8 JL |
787 | If either operand is a symbol, then it is the base. If |
788 | either operand is a CONST_INT, then the other is the base. */ | |
d4b60170 | 789 | if (GET_CODE (src_1) == CONST_INT || CONSTANT_P (src_0)) |
2a2c8203 | 790 | return find_base_value (src_0); |
d4b60170 | 791 | else if (GET_CODE (src_0) == CONST_INT || CONSTANT_P (src_1)) |
ec907dd8 JL |
792 | return find_base_value (src_1); |
793 | ||
d4b60170 | 794 | /* This might not be necessary anymore: |
ec907dd8 JL |
795 | If either operand is a REG that is a known pointer, then it |
796 | is the base. */ | |
3502dc9c | 797 | else if (GET_CODE (src_0) == REG && REG_POINTER (src_0)) |
2a2c8203 | 798 | return find_base_value (src_0); |
3502dc9c | 799 | else if (GET_CODE (src_1) == REG && REG_POINTER (src_1)) |
2a2c8203 JC |
800 | return find_base_value (src_1); |
801 | ||
9ae8ffe7 | 802 | return 0; |
2a2c8203 JC |
803 | } |
804 | ||
805 | case LO_SUM: | |
806 | /* The standard form is (lo_sum reg sym) so look only at the | |
807 | second operand. */ | |
808 | return find_base_value (XEXP (src, 1)); | |
9ae8ffe7 JL |
809 | |
810 | case AND: | |
811 | /* If the second operand is constant set the base | |
812 | address to the first operand. */ | |
2a2c8203 JC |
813 | if (GET_CODE (XEXP (src, 1)) == CONST_INT && INTVAL (XEXP (src, 1)) != 0) |
814 | return find_base_value (XEXP (src, 0)); | |
9ae8ffe7 JL |
815 | return 0; |
816 | ||
61f0131c R |
817 | case TRUNCATE: |
818 | if (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (Pmode)) | |
819 | break; | |
820 | /* Fall through. */ | |
de12be17 JC |
821 | case ZERO_EXTEND: |
822 | case SIGN_EXTEND: /* used for NT/Alpha pointers */ | |
9ae8ffe7 | 823 | case HIGH: |
2a2c8203 | 824 | return find_base_value (XEXP (src, 0)); |
1d300e19 KG |
825 | |
826 | default: | |
827 | break; | |
9ae8ffe7 JL |
828 | } |
829 | ||
830 | return 0; | |
831 | } | |
832 | ||
833 | /* Called from init_alias_analysis indirectly through note_stores. */ | |
834 | ||
d4b60170 | 835 | /* While scanning insns to find base values, reg_seen[N] is nonzero if |
9ae8ffe7 JL |
836 | register N has been set in this function. */ |
837 | static char *reg_seen; | |
838 | ||
13309a5f JC |
839 | /* Addresses which are known not to alias anything else are identified |
840 | by a unique integer. */ | |
ec907dd8 JL |
841 | static int unique_id; |
842 | ||
2a2c8203 | 843 | static void |
84832317 | 844 | record_set (dest, set, data) |
9ae8ffe7 | 845 | rtx dest, set; |
84832317 | 846 | void *data ATTRIBUTE_UNUSED; |
9ae8ffe7 | 847 | { |
ac606739 | 848 | register unsigned regno; |
9ae8ffe7 JL |
849 | rtx src; |
850 | ||
851 | if (GET_CODE (dest) != REG) | |
852 | return; | |
853 | ||
fb6754f0 | 854 | regno = REGNO (dest); |
9ae8ffe7 | 855 | |
ac606739 GS |
856 | if (regno >= reg_base_value_size) |
857 | abort (); | |
858 | ||
9ae8ffe7 JL |
859 | if (set) |
860 | { | |
861 | /* A CLOBBER wipes out any old value but does not prevent a previously | |
862 | unset register from acquiring a base address (i.e. reg_seen is not | |
863 | set). */ | |
864 | if (GET_CODE (set) == CLOBBER) | |
865 | { | |
ec907dd8 | 866 | new_reg_base_value[regno] = 0; |
9ae8ffe7 JL |
867 | return; |
868 | } | |
869 | src = SET_SRC (set); | |
870 | } | |
871 | else | |
872 | { | |
9ae8ffe7 JL |
873 | if (reg_seen[regno]) |
874 | { | |
ec907dd8 | 875 | new_reg_base_value[regno] = 0; |
9ae8ffe7 JL |
876 | return; |
877 | } | |
878 | reg_seen[regno] = 1; | |
38a448ca RH |
879 | new_reg_base_value[regno] = gen_rtx_ADDRESS (Pmode, |
880 | GEN_INT (unique_id++)); | |
9ae8ffe7 JL |
881 | return; |
882 | } | |
883 | ||
884 | /* This is not the first set. If the new value is not related to the | |
885 | old value, forget the base value. Note that the following code is | |
886 | not detected: | |
887 | extern int x, y; int *p = &x; p += (&y-&x); | |
888 | ANSI C does not allow computing the difference of addresses | |
889 | of distinct top level objects. */ | |
ec907dd8 | 890 | if (new_reg_base_value[regno]) |
9ae8ffe7 JL |
891 | switch (GET_CODE (src)) |
892 | { | |
2a2c8203 | 893 | case LO_SUM: |
9ae8ffe7 JL |
894 | case MINUS: |
895 | if (XEXP (src, 0) != dest && XEXP (src, 1) != dest) | |
ec907dd8 | 896 | new_reg_base_value[regno] = 0; |
9ae8ffe7 | 897 | break; |
61f0131c R |
898 | case PLUS: |
899 | /* If the value we add in the PLUS is also a valid base value, | |
900 | this might be the actual base value, and the original value | |
901 | an index. */ | |
902 | { | |
903 | rtx other = NULL_RTX; | |
904 | ||
905 | if (XEXP (src, 0) == dest) | |
906 | other = XEXP (src, 1); | |
907 | else if (XEXP (src, 1) == dest) | |
908 | other = XEXP (src, 0); | |
909 | ||
910 | if (! other || find_base_value (other)) | |
911 | new_reg_base_value[regno] = 0; | |
912 | break; | |
913 | } | |
9ae8ffe7 JL |
914 | case AND: |
915 | if (XEXP (src, 0) != dest || GET_CODE (XEXP (src, 1)) != CONST_INT) | |
ec907dd8 | 916 | new_reg_base_value[regno] = 0; |
9ae8ffe7 | 917 | break; |
9ae8ffe7 | 918 | default: |
ec907dd8 | 919 | new_reg_base_value[regno] = 0; |
9ae8ffe7 JL |
920 | break; |
921 | } | |
922 | /* If this is the first set of a register, record the value. */ | |
923 | else if ((regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno]) | |
ec907dd8 JL |
924 | && ! reg_seen[regno] && new_reg_base_value[regno] == 0) |
925 | new_reg_base_value[regno] = find_base_value (src); | |
9ae8ffe7 JL |
926 | |
927 | reg_seen[regno] = 1; | |
928 | } | |
929 | ||
ac3d9668 RK |
930 | /* Called from loop optimization when a new pseudo-register is |
931 | created. It indicates that REGNO is being set to VAL. f INVARIANT | |
932 | is true then this value also describes an invariant relationship | |
933 | which can be used to deduce that two registers with unknown values | |
934 | are different. */ | |
d4b60170 | 935 | |
9ae8ffe7 | 936 | void |
de12be17 | 937 | record_base_value (regno, val, invariant) |
ac3d9668 | 938 | unsigned int regno; |
9ae8ffe7 | 939 | rtx val; |
de12be17 | 940 | int invariant; |
9ae8ffe7 | 941 | { |
ac3d9668 | 942 | if (regno >= reg_base_value_size) |
9ae8ffe7 | 943 | return; |
de12be17 | 944 | |
de12be17 JC |
945 | if (invariant && alias_invariant) |
946 | alias_invariant[regno] = val; | |
947 | ||
9ae8ffe7 JL |
948 | if (GET_CODE (val) == REG) |
949 | { | |
fb6754f0 BS |
950 | if (REGNO (val) < reg_base_value_size) |
951 | reg_base_value[regno] = reg_base_value[REGNO (val)]; | |
d4b60170 | 952 | |
9ae8ffe7 JL |
953 | return; |
954 | } | |
d4b60170 | 955 | |
9ae8ffe7 JL |
956 | reg_base_value[regno] = find_base_value (val); |
957 | } | |
958 | ||
db048faf MM |
959 | /* Returns a canonical version of X, from the point of view alias |
960 | analysis. (For example, if X is a MEM whose address is a register, | |
961 | and the register has a known value (say a SYMBOL_REF), then a MEM | |
962 | whose address is the SYMBOL_REF is returned.) */ | |
963 | ||
964 | rtx | |
9ae8ffe7 JL |
965 | canon_rtx (x) |
966 | rtx x; | |
967 | { | |
968 | /* Recursively look for equivalences. */ | |
fb6754f0 BS |
969 | if (GET_CODE (x) == REG && REGNO (x) >= FIRST_PSEUDO_REGISTER |
970 | && REGNO (x) < reg_known_value_size) | |
971 | return reg_known_value[REGNO (x)] == x | |
972 | ? x : canon_rtx (reg_known_value[REGNO (x)]); | |
9ae8ffe7 JL |
973 | else if (GET_CODE (x) == PLUS) |
974 | { | |
975 | rtx x0 = canon_rtx (XEXP (x, 0)); | |
976 | rtx x1 = canon_rtx (XEXP (x, 1)); | |
977 | ||
978 | if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1)) | |
979 | { | |
9ae8ffe7 | 980 | if (GET_CODE (x0) == CONST_INT) |
ed8908e7 | 981 | return plus_constant (x1, INTVAL (x0)); |
9ae8ffe7 | 982 | else if (GET_CODE (x1) == CONST_INT) |
ed8908e7 | 983 | return plus_constant (x0, INTVAL (x1)); |
38a448ca | 984 | return gen_rtx_PLUS (GET_MODE (x), x0, x1); |
9ae8ffe7 JL |
985 | } |
986 | } | |
d4b60170 | 987 | |
9ae8ffe7 JL |
988 | /* This gives us much better alias analysis when called from |
989 | the loop optimizer. Note we want to leave the original | |
990 | MEM alone, but need to return the canonicalized MEM with | |
991 | all the flags with their original values. */ | |
992 | else if (GET_CODE (x) == MEM) | |
f1ec5147 | 993 | x = replace_equiv_address_nv (x, canon_rtx (XEXP (x, 0))); |
d4b60170 | 994 | |
9ae8ffe7 JL |
995 | return x; |
996 | } | |
997 | ||
998 | /* Return 1 if X and Y are identical-looking rtx's. | |
999 | ||
1000 | We use the data in reg_known_value above to see if two registers with | |
1001 | different numbers are, in fact, equivalent. */ | |
1002 | ||
1003 | static int | |
1004 | rtx_equal_for_memref_p (x, y) | |
1005 | rtx x, y; | |
1006 | { | |
1007 | register int i; | |
1008 | register int j; | |
1009 | register enum rtx_code code; | |
6f7d635c | 1010 | register const char *fmt; |
9ae8ffe7 JL |
1011 | |
1012 | if (x == 0 && y == 0) | |
1013 | return 1; | |
1014 | if (x == 0 || y == 0) | |
1015 | return 0; | |
d4b60170 | 1016 | |
9ae8ffe7 JL |
1017 | x = canon_rtx (x); |
1018 | y = canon_rtx (y); | |
1019 | ||
1020 | if (x == y) | |
1021 | return 1; | |
1022 | ||
1023 | code = GET_CODE (x); | |
1024 | /* Rtx's of different codes cannot be equal. */ | |
1025 | if (code != GET_CODE (y)) | |
1026 | return 0; | |
1027 | ||
1028 | /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. | |
1029 | (REG:SI x) and (REG:HI x) are NOT equivalent. */ | |
1030 | ||
1031 | if (GET_MODE (x) != GET_MODE (y)) | |
1032 | return 0; | |
1033 | ||
db048faf MM |
1034 | /* Some RTL can be compared without a recursive examination. */ |
1035 | switch (code) | |
1036 | { | |
1037 | case REG: | |
1038 | return REGNO (x) == REGNO (y); | |
1039 | ||
1040 | case LABEL_REF: | |
1041 | return XEXP (x, 0) == XEXP (y, 0); | |
1042 | ||
1043 | case SYMBOL_REF: | |
1044 | return XSTR (x, 0) == XSTR (y, 0); | |
1045 | ||
1046 | case CONST_INT: | |
1047 | case CONST_DOUBLE: | |
1048 | /* There's no need to compare the contents of CONST_DOUBLEs or | |
1049 | CONST_INTs because pointer equality is a good enough | |
1050 | comparison for these nodes. */ | |
1051 | return 0; | |
1052 | ||
1053 | case ADDRESSOF: | |
831ecbd4 RK |
1054 | return (XINT (x, 1) == XINT (y, 1) |
1055 | && rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0))); | |
db048faf MM |
1056 | |
1057 | default: | |
1058 | break; | |
1059 | } | |
9ae8ffe7 JL |
1060 | |
1061 | /* For commutative operations, the RTX match if the operand match in any | |
1062 | order. Also handle the simple binary and unary cases without a loop. */ | |
1063 | if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c') | |
1064 | return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)) | |
1065 | && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1))) | |
1066 | || (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1)) | |
1067 | && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0)))); | |
1068 | else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2') | |
1069 | return (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)) | |
1070 | && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1))); | |
1071 | else if (GET_RTX_CLASS (code) == '1') | |
1072 | return rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)); | |
1073 | ||
1074 | /* Compare the elements. If any pair of corresponding elements | |
de12be17 JC |
1075 | fail to match, return 0 for the whole things. |
1076 | ||
1077 | Limit cases to types which actually appear in addresses. */ | |
9ae8ffe7 JL |
1078 | |
1079 | fmt = GET_RTX_FORMAT (code); | |
1080 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1081 | { | |
1082 | switch (fmt[i]) | |
1083 | { | |
9ae8ffe7 JL |
1084 | case 'i': |
1085 | if (XINT (x, i) != XINT (y, i)) | |
1086 | return 0; | |
1087 | break; | |
1088 | ||
9ae8ffe7 JL |
1089 | case 'E': |
1090 | /* Two vectors must have the same length. */ | |
1091 | if (XVECLEN (x, i) != XVECLEN (y, i)) | |
1092 | return 0; | |
1093 | ||
1094 | /* And the corresponding elements must match. */ | |
1095 | for (j = 0; j < XVECLEN (x, i); j++) | |
d4b60170 RK |
1096 | if (rtx_equal_for_memref_p (XVECEXP (x, i, j), |
1097 | XVECEXP (y, i, j)) == 0) | |
9ae8ffe7 JL |
1098 | return 0; |
1099 | break; | |
1100 | ||
1101 | case 'e': | |
1102 | if (rtx_equal_for_memref_p (XEXP (x, i), XEXP (y, i)) == 0) | |
1103 | return 0; | |
1104 | break; | |
1105 | ||
3237ac18 AH |
1106 | /* This can happen for asm operands. */ |
1107 | case 's': | |
1108 | if (strcmp (XSTR (x, i), XSTR (y, i))) | |
1109 | return 0; | |
1110 | break; | |
1111 | ||
aee21ba9 JL |
1112 | /* This can happen for an asm which clobbers memory. */ |
1113 | case '0': | |
1114 | break; | |
1115 | ||
9ae8ffe7 JL |
1116 | /* It is believed that rtx's at this level will never |
1117 | contain anything but integers and other rtx's, | |
1118 | except for within LABEL_REFs and SYMBOL_REFs. */ | |
1119 | default: | |
1120 | abort (); | |
1121 | } | |
1122 | } | |
1123 | return 1; | |
1124 | } | |
1125 | ||
1126 | /* Given an rtx X, find a SYMBOL_REF or LABEL_REF within | |
1127 | X and return it, or return 0 if none found. */ | |
1128 | ||
1129 | static rtx | |
1130 | find_symbolic_term (x) | |
1131 | rtx x; | |
1132 | { | |
1133 | register int i; | |
1134 | register enum rtx_code code; | |
6f7d635c | 1135 | register const char *fmt; |
9ae8ffe7 JL |
1136 | |
1137 | code = GET_CODE (x); | |
1138 | if (code == SYMBOL_REF || code == LABEL_REF) | |
1139 | return x; | |
1140 | if (GET_RTX_CLASS (code) == 'o') | |
1141 | return 0; | |
1142 | ||
1143 | fmt = GET_RTX_FORMAT (code); | |
1144 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
1145 | { | |
1146 | rtx t; | |
1147 | ||
1148 | if (fmt[i] == 'e') | |
1149 | { | |
1150 | t = find_symbolic_term (XEXP (x, i)); | |
1151 | if (t != 0) | |
1152 | return t; | |
1153 | } | |
1154 | else if (fmt[i] == 'E') | |
1155 | break; | |
1156 | } | |
1157 | return 0; | |
1158 | } | |
1159 | ||
1160 | static rtx | |
1161 | find_base_term (x) | |
1162 | register rtx x; | |
1163 | { | |
eab5c70a BS |
1164 | cselib_val *val; |
1165 | struct elt_loc_list *l; | |
1166 | ||
b949ea8b JW |
1167 | #if defined (FIND_BASE_TERM) |
1168 | /* Try machine-dependent ways to find the base term. */ | |
1169 | x = FIND_BASE_TERM (x); | |
1170 | #endif | |
1171 | ||
9ae8ffe7 JL |
1172 | switch (GET_CODE (x)) |
1173 | { | |
1174 | case REG: | |
1175 | return REG_BASE_VALUE (x); | |
1176 | ||
de12be17 JC |
1177 | case ZERO_EXTEND: |
1178 | case SIGN_EXTEND: /* Used for Alpha/NT pointers */ | |
9ae8ffe7 | 1179 | case HIGH: |
6d849a2a JL |
1180 | case PRE_INC: |
1181 | case PRE_DEC: | |
1182 | case POST_INC: | |
1183 | case POST_DEC: | |
1184 | return find_base_term (XEXP (x, 0)); | |
1185 | ||
eab5c70a BS |
1186 | case VALUE: |
1187 | val = CSELIB_VAL_PTR (x); | |
1188 | for (l = val->locs; l; l = l->next) | |
1189 | if ((x = find_base_term (l->loc)) != 0) | |
1190 | return x; | |
1191 | return 0; | |
1192 | ||
9ae8ffe7 JL |
1193 | case CONST: |
1194 | x = XEXP (x, 0); | |
1195 | if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS) | |
1196 | return 0; | |
1197 | /* fall through */ | |
1198 | case LO_SUM: | |
1199 | case PLUS: | |
1200 | case MINUS: | |
1201 | { | |
3c567fae JL |
1202 | rtx tmp1 = XEXP (x, 0); |
1203 | rtx tmp2 = XEXP (x, 1); | |
1204 | ||
1205 | /* This is a litle bit tricky since we have to determine which of | |
1206 | the two operands represents the real base address. Otherwise this | |
1207 | routine may return the index register instead of the base register. | |
1208 | ||
1209 | That may cause us to believe no aliasing was possible, when in | |
1210 | fact aliasing is possible. | |
1211 | ||
1212 | We use a few simple tests to guess the base register. Additional | |
1213 | tests can certainly be added. For example, if one of the operands | |
1214 | is a shift or multiply, then it must be the index register and the | |
1215 | other operand is the base register. */ | |
1216 | ||
b949ea8b JW |
1217 | if (tmp1 == pic_offset_table_rtx && CONSTANT_P (tmp2)) |
1218 | return find_base_term (tmp2); | |
1219 | ||
3c567fae JL |
1220 | /* If either operand is known to be a pointer, then use it |
1221 | to determine the base term. */ | |
3502dc9c | 1222 | if (REG_P (tmp1) && REG_POINTER (tmp1)) |
3c567fae JL |
1223 | return find_base_term (tmp1); |
1224 | ||
3502dc9c | 1225 | if (REG_P (tmp2) && REG_POINTER (tmp2)) |
3c567fae JL |
1226 | return find_base_term (tmp2); |
1227 | ||
1228 | /* Neither operand was known to be a pointer. Go ahead and find the | |
1229 | base term for both operands. */ | |
1230 | tmp1 = find_base_term (tmp1); | |
1231 | tmp2 = find_base_term (tmp2); | |
1232 | ||
1233 | /* If either base term is named object or a special address | |
1234 | (like an argument or stack reference), then use it for the | |
1235 | base term. */ | |
d4b60170 | 1236 | if (tmp1 != 0 |
3c567fae JL |
1237 | && (GET_CODE (tmp1) == SYMBOL_REF |
1238 | || GET_CODE (tmp1) == LABEL_REF | |
1239 | || (GET_CODE (tmp1) == ADDRESS | |
1240 | && GET_MODE (tmp1) != VOIDmode))) | |
1241 | return tmp1; | |
1242 | ||
d4b60170 | 1243 | if (tmp2 != 0 |
3c567fae JL |
1244 | && (GET_CODE (tmp2) == SYMBOL_REF |
1245 | || GET_CODE (tmp2) == LABEL_REF | |
1246 | || (GET_CODE (tmp2) == ADDRESS | |
1247 | && GET_MODE (tmp2) != VOIDmode))) | |
1248 | return tmp2; | |
1249 | ||
1250 | /* We could not determine which of the two operands was the | |
1251 | base register and which was the index. So we can determine | |
1252 | nothing from the base alias check. */ | |
1253 | return 0; | |
9ae8ffe7 JL |
1254 | } |
1255 | ||
1256 | case AND: | |
1257 | if (GET_CODE (XEXP (x, 0)) == REG && GET_CODE (XEXP (x, 1)) == CONST_INT) | |
1258 | return REG_BASE_VALUE (XEXP (x, 0)); | |
1259 | return 0; | |
1260 | ||
1261 | case SYMBOL_REF: | |
1262 | case LABEL_REF: | |
1263 | return x; | |
1264 | ||
d982e46e | 1265 | case ADDRESSOF: |
bb07060a | 1266 | return REG_BASE_VALUE (frame_pointer_rtx); |
d982e46e | 1267 | |
9ae8ffe7 JL |
1268 | default: |
1269 | return 0; | |
1270 | } | |
1271 | } | |
1272 | ||
1273 | /* Return 0 if the addresses X and Y are known to point to different | |
1274 | objects, 1 if they might be pointers to the same object. */ | |
1275 | ||
1276 | static int | |
56ee9281 | 1277 | base_alias_check (x, y, x_mode, y_mode) |
9ae8ffe7 | 1278 | rtx x, y; |
56ee9281 | 1279 | enum machine_mode x_mode, y_mode; |
9ae8ffe7 JL |
1280 | { |
1281 | rtx x_base = find_base_term (x); | |
1282 | rtx y_base = find_base_term (y); | |
1283 | ||
1c72c7f6 JC |
1284 | /* If the address itself has no known base see if a known equivalent |
1285 | value has one. If either address still has no known base, nothing | |
1286 | is known about aliasing. */ | |
1287 | if (x_base == 0) | |
1288 | { | |
1289 | rtx x_c; | |
d4b60170 | 1290 | |
1c72c7f6 JC |
1291 | if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x) |
1292 | return 1; | |
d4b60170 | 1293 | |
1c72c7f6 JC |
1294 | x_base = find_base_term (x_c); |
1295 | if (x_base == 0) | |
1296 | return 1; | |
1297 | } | |
9ae8ffe7 | 1298 | |
1c72c7f6 JC |
1299 | if (y_base == 0) |
1300 | { | |
1301 | rtx y_c; | |
1302 | if (! flag_expensive_optimizations || (y_c = canon_rtx (y)) == y) | |
1303 | return 1; | |
d4b60170 | 1304 | |
1c72c7f6 JC |
1305 | y_base = find_base_term (y_c); |
1306 | if (y_base == 0) | |
1307 | return 1; | |
1308 | } | |
1309 | ||
1310 | /* If the base addresses are equal nothing is known about aliasing. */ | |
1311 | if (rtx_equal_p (x_base, y_base)) | |
9ae8ffe7 JL |
1312 | return 1; |
1313 | ||
56ee9281 RH |
1314 | /* The base addresses of the read and write are different expressions. |
1315 | If they are both symbols and they are not accessed via AND, there is | |
1316 | no conflict. We can bring knowledge of object alignment into play | |
1317 | here. For example, on alpha, "char a, b;" can alias one another, | |
1318 | though "char a; long b;" cannot. */ | |
9ae8ffe7 | 1319 | if (GET_CODE (x_base) != ADDRESS && GET_CODE (y_base) != ADDRESS) |
c02f035f | 1320 | { |
56ee9281 RH |
1321 | if (GET_CODE (x) == AND && GET_CODE (y) == AND) |
1322 | return 1; | |
1323 | if (GET_CODE (x) == AND | |
1324 | && (GET_CODE (XEXP (x, 1)) != CONST_INT | |
8fa2140d | 1325 | || (int) GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1)))) |
56ee9281 RH |
1326 | return 1; |
1327 | if (GET_CODE (y) == AND | |
1328 | && (GET_CODE (XEXP (y, 1)) != CONST_INT | |
8fa2140d | 1329 | || (int) GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1)))) |
56ee9281 | 1330 | return 1; |
b2972551 JL |
1331 | /* Differing symbols never alias. */ |
1332 | return 0; | |
c02f035f | 1333 | } |
9ae8ffe7 JL |
1334 | |
1335 | /* If one address is a stack reference there can be no alias: | |
1336 | stack references using different base registers do not alias, | |
1337 | a stack reference can not alias a parameter, and a stack reference | |
1338 | can not alias a global. */ | |
1339 | if ((GET_CODE (x_base) == ADDRESS && GET_MODE (x_base) == Pmode) | |
1340 | || (GET_CODE (y_base) == ADDRESS && GET_MODE (y_base) == Pmode)) | |
1341 | return 0; | |
1342 | ||
1343 | if (! flag_argument_noalias) | |
1344 | return 1; | |
1345 | ||
1346 | if (flag_argument_noalias > 1) | |
1347 | return 0; | |
1348 | ||
1349 | /* Weak noalias assertion (arguments are distinct, but may match globals). */ | |
1350 | return ! (GET_MODE (x_base) == VOIDmode && GET_MODE (y_base) == VOIDmode); | |
1351 | } | |
1352 | ||
eab5c70a BS |
1353 | /* Convert the address X into something we can use. This is done by returning |
1354 | it unchanged unless it is a value; in the latter case we call cselib to get | |
1355 | a more useful rtx. */ | |
3bdf5ad1 | 1356 | |
a13d4ebf | 1357 | rtx |
eab5c70a BS |
1358 | get_addr (x) |
1359 | rtx x; | |
1360 | { | |
1361 | cselib_val *v; | |
1362 | struct elt_loc_list *l; | |
1363 | ||
1364 | if (GET_CODE (x) != VALUE) | |
1365 | return x; | |
1366 | v = CSELIB_VAL_PTR (x); | |
1367 | for (l = v->locs; l; l = l->next) | |
1368 | if (CONSTANT_P (l->loc)) | |
1369 | return l->loc; | |
1370 | for (l = v->locs; l; l = l->next) | |
1371 | if (GET_CODE (l->loc) != REG && GET_CODE (l->loc) != MEM) | |
1372 | return l->loc; | |
1373 | if (v->locs) | |
1374 | return v->locs->loc; | |
1375 | return x; | |
1376 | } | |
1377 | ||
39cec1ac MH |
1378 | /* Return the address of the (N_REFS + 1)th memory reference to ADDR |
1379 | where SIZE is the size in bytes of the memory reference. If ADDR | |
1380 | is not modified by the memory reference then ADDR is returned. */ | |
1381 | ||
1382 | rtx | |
1383 | addr_side_effect_eval (addr, size, n_refs) | |
1384 | rtx addr; | |
1385 | int size; | |
1386 | int n_refs; | |
1387 | { | |
1388 | int offset = 0; | |
1389 | ||
1390 | switch (GET_CODE (addr)) | |
1391 | { | |
1392 | case PRE_INC: | |
1393 | offset = (n_refs + 1) * size; | |
1394 | break; | |
1395 | case PRE_DEC: | |
1396 | offset = -(n_refs + 1) * size; | |
1397 | break; | |
1398 | case POST_INC: | |
1399 | offset = n_refs * size; | |
1400 | break; | |
1401 | case POST_DEC: | |
1402 | offset = -n_refs * size; | |
1403 | break; | |
1404 | ||
1405 | default: | |
1406 | return addr; | |
1407 | } | |
1408 | ||
1409 | if (offset) | |
1410 | addr = gen_rtx_PLUS (GET_MODE (addr), XEXP (addr, 0), GEN_INT (offset)); | |
1411 | else | |
1412 | addr = XEXP (addr, 0); | |
1413 | ||
1414 | return addr; | |
1415 | } | |
1416 | ||
9ae8ffe7 JL |
1417 | /* Return nonzero if X and Y (memory addresses) could reference the |
1418 | same location in memory. C is an offset accumulator. When | |
1419 | C is nonzero, we are testing aliases between X and Y + C. | |
1420 | XSIZE is the size in bytes of the X reference, | |
1421 | similarly YSIZE is the size in bytes for Y. | |
1422 | ||
1423 | If XSIZE or YSIZE is zero, we do not know the amount of memory being | |
1424 | referenced (the reference was BLKmode), so make the most pessimistic | |
1425 | assumptions. | |
1426 | ||
c02f035f RH |
1427 | If XSIZE or YSIZE is negative, we may access memory outside the object |
1428 | being referenced as a side effect. This can happen when using AND to | |
1429 | align memory references, as is done on the Alpha. | |
1430 | ||
9ae8ffe7 | 1431 | Nice to notice that varying addresses cannot conflict with fp if no |
0211b6ab | 1432 | local variables had their addresses taken, but that's too hard now. */ |
9ae8ffe7 | 1433 | |
9ae8ffe7 JL |
1434 | static int |
1435 | memrefs_conflict_p (xsize, x, ysize, y, c) | |
1436 | register rtx x, y; | |
1437 | int xsize, ysize; | |
1438 | HOST_WIDE_INT c; | |
1439 | { | |
eab5c70a BS |
1440 | if (GET_CODE (x) == VALUE) |
1441 | x = get_addr (x); | |
1442 | if (GET_CODE (y) == VALUE) | |
1443 | y = get_addr (y); | |
9ae8ffe7 JL |
1444 | if (GET_CODE (x) == HIGH) |
1445 | x = XEXP (x, 0); | |
1446 | else if (GET_CODE (x) == LO_SUM) | |
1447 | x = XEXP (x, 1); | |
1448 | else | |
39cec1ac | 1449 | x = canon_rtx (addr_side_effect_eval (x, xsize, 0)); |
9ae8ffe7 JL |
1450 | if (GET_CODE (y) == HIGH) |
1451 | y = XEXP (y, 0); | |
1452 | else if (GET_CODE (y) == LO_SUM) | |
1453 | y = XEXP (y, 1); | |
1454 | else | |
39cec1ac | 1455 | y = canon_rtx (addr_side_effect_eval (y, ysize, 0)); |
9ae8ffe7 JL |
1456 | |
1457 | if (rtx_equal_for_memref_p (x, y)) | |
1458 | { | |
c02f035f | 1459 | if (xsize <= 0 || ysize <= 0) |
9ae8ffe7 JL |
1460 | return 1; |
1461 | if (c >= 0 && xsize > c) | |
1462 | return 1; | |
1463 | if (c < 0 && ysize+c > 0) | |
1464 | return 1; | |
1465 | return 0; | |
1466 | } | |
1467 | ||
6e73e666 JC |
1468 | /* This code used to check for conflicts involving stack references and |
1469 | globals but the base address alias code now handles these cases. */ | |
9ae8ffe7 JL |
1470 | |
1471 | if (GET_CODE (x) == PLUS) | |
1472 | { | |
1473 | /* The fact that X is canonicalized means that this | |
1474 | PLUS rtx is canonicalized. */ | |
1475 | rtx x0 = XEXP (x, 0); | |
1476 | rtx x1 = XEXP (x, 1); | |
1477 | ||
1478 | if (GET_CODE (y) == PLUS) | |
1479 | { | |
1480 | /* The fact that Y is canonicalized means that this | |
1481 | PLUS rtx is canonicalized. */ | |
1482 | rtx y0 = XEXP (y, 0); | |
1483 | rtx y1 = XEXP (y, 1); | |
1484 | ||
1485 | if (rtx_equal_for_memref_p (x1, y1)) | |
1486 | return memrefs_conflict_p (xsize, x0, ysize, y0, c); | |
1487 | if (rtx_equal_for_memref_p (x0, y0)) | |
1488 | return memrefs_conflict_p (xsize, x1, ysize, y1, c); | |
1489 | if (GET_CODE (x1) == CONST_INT) | |
63be02db JM |
1490 | { |
1491 | if (GET_CODE (y1) == CONST_INT) | |
1492 | return memrefs_conflict_p (xsize, x0, ysize, y0, | |
1493 | c - INTVAL (x1) + INTVAL (y1)); | |
1494 | else | |
1495 | return memrefs_conflict_p (xsize, x0, ysize, y, | |
1496 | c - INTVAL (x1)); | |
1497 | } | |
9ae8ffe7 JL |
1498 | else if (GET_CODE (y1) == CONST_INT) |
1499 | return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1)); | |
1500 | ||
6e73e666 | 1501 | return 1; |
9ae8ffe7 JL |
1502 | } |
1503 | else if (GET_CODE (x1) == CONST_INT) | |
1504 | return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1)); | |
1505 | } | |
1506 | else if (GET_CODE (y) == PLUS) | |
1507 | { | |
1508 | /* The fact that Y is canonicalized means that this | |
1509 | PLUS rtx is canonicalized. */ | |
1510 | rtx y0 = XEXP (y, 0); | |
1511 | rtx y1 = XEXP (y, 1); | |
1512 | ||
1513 | if (GET_CODE (y1) == CONST_INT) | |
1514 | return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1)); | |
1515 | else | |
1516 | return 1; | |
1517 | } | |
1518 | ||
1519 | if (GET_CODE (x) == GET_CODE (y)) | |
1520 | switch (GET_CODE (x)) | |
1521 | { | |
1522 | case MULT: | |
1523 | { | |
1524 | /* Handle cases where we expect the second operands to be the | |
1525 | same, and check only whether the first operand would conflict | |
1526 | or not. */ | |
1527 | rtx x0, y0; | |
1528 | rtx x1 = canon_rtx (XEXP (x, 1)); | |
1529 | rtx y1 = canon_rtx (XEXP (y, 1)); | |
1530 | if (! rtx_equal_for_memref_p (x1, y1)) | |
1531 | return 1; | |
1532 | x0 = canon_rtx (XEXP (x, 0)); | |
1533 | y0 = canon_rtx (XEXP (y, 0)); | |
1534 | if (rtx_equal_for_memref_p (x0, y0)) | |
1535 | return (xsize == 0 || ysize == 0 | |
1536 | || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0)); | |
1537 | ||
1538 | /* Can't properly adjust our sizes. */ | |
1539 | if (GET_CODE (x1) != CONST_INT) | |
1540 | return 1; | |
1541 | xsize /= INTVAL (x1); | |
1542 | ysize /= INTVAL (x1); | |
1543 | c /= INTVAL (x1); | |
1544 | return memrefs_conflict_p (xsize, x0, ysize, y0, c); | |
1545 | } | |
1d300e19 | 1546 | |
de12be17 JC |
1547 | case REG: |
1548 | /* Are these registers known not to be equal? */ | |
1549 | if (alias_invariant) | |
1550 | { | |
e51712db | 1551 | unsigned int r_x = REGNO (x), r_y = REGNO (y); |
de12be17 JC |
1552 | rtx i_x, i_y; /* invariant relationships of X and Y */ |
1553 | ||
1554 | i_x = r_x >= reg_base_value_size ? 0 : alias_invariant[r_x]; | |
1555 | i_y = r_y >= reg_base_value_size ? 0 : alias_invariant[r_y]; | |
1556 | ||
1557 | if (i_x == 0 && i_y == 0) | |
1558 | break; | |
1559 | ||
1560 | if (! memrefs_conflict_p (xsize, i_x ? i_x : x, | |
1561 | ysize, i_y ? i_y : y, c)) | |
1562 | return 0; | |
1563 | } | |
1564 | break; | |
1565 | ||
1d300e19 KG |
1566 | default: |
1567 | break; | |
9ae8ffe7 JL |
1568 | } |
1569 | ||
1570 | /* Treat an access through an AND (e.g. a subword access on an Alpha) | |
56ee9281 RH |
1571 | as an access with indeterminate size. Assume that references |
1572 | besides AND are aligned, so if the size of the other reference is | |
1573 | at least as large as the alignment, assume no other overlap. */ | |
9ae8ffe7 | 1574 | if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT) |
56ee9281 | 1575 | { |
02e3377d | 1576 | if (GET_CODE (y) == AND || ysize < -INTVAL (XEXP (x, 1))) |
56ee9281 RH |
1577 | xsize = -1; |
1578 | return memrefs_conflict_p (xsize, XEXP (x, 0), ysize, y, c); | |
1579 | } | |
9ae8ffe7 | 1580 | if (GET_CODE (y) == AND && GET_CODE (XEXP (y, 1)) == CONST_INT) |
c02f035f | 1581 | { |
56ee9281 | 1582 | /* ??? If we are indexing far enough into the array/structure, we |
c02f035f RH |
1583 | may yet be able to determine that we can not overlap. But we |
1584 | also need to that we are far enough from the end not to overlap | |
56ee9281 | 1585 | a following reference, so we do nothing with that for now. */ |
02e3377d | 1586 | if (GET_CODE (x) == AND || xsize < -INTVAL (XEXP (y, 1))) |
56ee9281 RH |
1587 | ysize = -1; |
1588 | return memrefs_conflict_p (xsize, x, ysize, XEXP (y, 0), c); | |
c02f035f | 1589 | } |
9ae8ffe7 | 1590 | |
b24ea077 JW |
1591 | if (GET_CODE (x) == ADDRESSOF) |
1592 | { | |
1593 | if (y == frame_pointer_rtx | |
1594 | || GET_CODE (y) == ADDRESSOF) | |
1595 | return xsize <= 0 || ysize <= 0; | |
1596 | } | |
1597 | if (GET_CODE (y) == ADDRESSOF) | |
1598 | { | |
1599 | if (x == frame_pointer_rtx) | |
1600 | return xsize <= 0 || ysize <= 0; | |
1601 | } | |
d982e46e | 1602 | |
9ae8ffe7 JL |
1603 | if (CONSTANT_P (x)) |
1604 | { | |
1605 | if (GET_CODE (x) == CONST_INT && GET_CODE (y) == CONST_INT) | |
1606 | { | |
1607 | c += (INTVAL (y) - INTVAL (x)); | |
c02f035f | 1608 | return (xsize <= 0 || ysize <= 0 |
9ae8ffe7 JL |
1609 | || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0)); |
1610 | } | |
1611 | ||
1612 | if (GET_CODE (x) == CONST) | |
1613 | { | |
1614 | if (GET_CODE (y) == CONST) | |
1615 | return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), | |
1616 | ysize, canon_rtx (XEXP (y, 0)), c); | |
1617 | else | |
1618 | return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), | |
1619 | ysize, y, c); | |
1620 | } | |
1621 | if (GET_CODE (y) == CONST) | |
1622 | return memrefs_conflict_p (xsize, x, ysize, | |
1623 | canon_rtx (XEXP (y, 0)), c); | |
1624 | ||
1625 | if (CONSTANT_P (y)) | |
b949ea8b | 1626 | return (xsize <= 0 || ysize <= 0 |
c02f035f | 1627 | || (rtx_equal_for_memref_p (x, y) |
b949ea8b | 1628 | && ((c >= 0 && xsize > c) || (c < 0 && ysize+c > 0)))); |
9ae8ffe7 JL |
1629 | |
1630 | return 1; | |
1631 | } | |
1632 | return 1; | |
1633 | } | |
1634 | ||
1635 | /* Functions to compute memory dependencies. | |
1636 | ||
1637 | Since we process the insns in execution order, we can build tables | |
1638 | to keep track of what registers are fixed (and not aliased), what registers | |
1639 | are varying in known ways, and what registers are varying in unknown | |
1640 | ways. | |
1641 | ||
1642 | If both memory references are volatile, then there must always be a | |
1643 | dependence between the two references, since their order can not be | |
1644 | changed. A volatile and non-volatile reference can be interchanged | |
1645 | though. | |
1646 | ||
dc1618bc RK |
1647 | A MEM_IN_STRUCT reference at a non-AND varying address can never |
1648 | conflict with a non-MEM_IN_STRUCT reference at a fixed address. We | |
1649 | also must allow AND addresses, because they may generate accesses | |
1650 | outside the object being referenced. This is used to generate | |
1651 | aligned addresses from unaligned addresses, for instance, the alpha | |
1652 | storeqi_unaligned pattern. */ | |
9ae8ffe7 JL |
1653 | |
1654 | /* Read dependence: X is read after read in MEM takes place. There can | |
1655 | only be a dependence here if both reads are volatile. */ | |
1656 | ||
1657 | int | |
1658 | read_dependence (mem, x) | |
1659 | rtx mem; | |
1660 | rtx x; | |
1661 | { | |
1662 | return MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem); | |
1663 | } | |
1664 | ||
c6df88cb MM |
1665 | /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and |
1666 | MEM2 is a reference to a structure at a varying address, or returns | |
1667 | MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL | |
1668 | value is returned MEM1 and MEM2 can never alias. VARIES_P is used | |
1669 | to decide whether or not an address may vary; it should return | |
eab5c70a BS |
1670 | nonzero whenever variation is possible. |
1671 | MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */ | |
1672 | ||
2c72b78f | 1673 | static rtx |
eab5c70a BS |
1674 | fixed_scalar_and_varying_struct_p (mem1, mem2, mem1_addr, mem2_addr, varies_p) |
1675 | rtx mem1, mem2; | |
1676 | rtx mem1_addr, mem2_addr; | |
e38fe8e0 | 1677 | int (*varies_p) PARAMS ((rtx, int)); |
eab5c70a | 1678 | { |
3e0abe15 GK |
1679 | if (! flag_strict_aliasing) |
1680 | return NULL_RTX; | |
1681 | ||
c6df88cb | 1682 | if (MEM_SCALAR_P (mem1) && MEM_IN_STRUCT_P (mem2) |
e38fe8e0 | 1683 | && !varies_p (mem1_addr, 1) && varies_p (mem2_addr, 1)) |
c6df88cb MM |
1684 | /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a |
1685 | varying address. */ | |
1686 | return mem1; | |
1687 | ||
1688 | if (MEM_IN_STRUCT_P (mem1) && MEM_SCALAR_P (mem2) | |
e38fe8e0 | 1689 | && varies_p (mem1_addr, 1) && !varies_p (mem2_addr, 1)) |
c6df88cb MM |
1690 | /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a |
1691 | varying address. */ | |
1692 | return mem2; | |
1693 | ||
1694 | return NULL_RTX; | |
1695 | } | |
1696 | ||
1697 | /* Returns nonzero if something about the mode or address format MEM1 | |
1698 | indicates that it might well alias *anything*. */ | |
1699 | ||
2c72b78f | 1700 | static int |
c6df88cb MM |
1701 | aliases_everything_p (mem) |
1702 | rtx mem; | |
1703 | { | |
c6df88cb MM |
1704 | if (GET_CODE (XEXP (mem, 0)) == AND) |
1705 | /* If the address is an AND, its very hard to know at what it is | |
1706 | actually pointing. */ | |
1707 | return 1; | |
1708 | ||
1709 | return 0; | |
1710 | } | |
1711 | ||
9ae8ffe7 JL |
1712 | /* True dependence: X is read after store in MEM takes place. */ |
1713 | ||
1714 | int | |
1715 | true_dependence (mem, mem_mode, x, varies) | |
1716 | rtx mem; | |
1717 | enum machine_mode mem_mode; | |
1718 | rtx x; | |
e38fe8e0 | 1719 | int (*varies) PARAMS ((rtx, int)); |
9ae8ffe7 | 1720 | { |
6e73e666 | 1721 | register rtx x_addr, mem_addr; |
49982682 | 1722 | rtx base; |
9ae8ffe7 JL |
1723 | |
1724 | if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) | |
1725 | return 1; | |
1726 | ||
41472af8 MM |
1727 | if (DIFFERENT_ALIAS_SETS_P (x, mem)) |
1728 | return 0; | |
1729 | ||
b949ea8b JW |
1730 | /* Unchanging memory can't conflict with non-unchanging memory. |
1731 | A non-unchanging read can conflict with a non-unchanging write. | |
1732 | An unchanging read can conflict with an unchanging write since | |
1733 | there may be a single store to this address to initialize it. | |
ec569656 RK |
1734 | Note that an unchanging store can conflict with a non-unchanging read |
1735 | since we have to make conservative assumptions when we have a | |
1736 | record with readonly fields and we are copying the whole thing. | |
b949ea8b JW |
1737 | Just fall through to the code below to resolve potential conflicts. |
1738 | This won't handle all cases optimally, but the possible performance | |
1739 | loss should be negligible. */ | |
ec569656 | 1740 | if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem)) |
9ae8ffe7 JL |
1741 | return 0; |
1742 | ||
56ee9281 RH |
1743 | if (mem_mode == VOIDmode) |
1744 | mem_mode = GET_MODE (mem); | |
1745 | ||
eab5c70a BS |
1746 | x_addr = get_addr (XEXP (x, 0)); |
1747 | mem_addr = get_addr (XEXP (mem, 0)); | |
1748 | ||
55efb413 JW |
1749 | base = find_base_term (x_addr); |
1750 | if (base && (GET_CODE (base) == LABEL_REF | |
1751 | || (GET_CODE (base) == SYMBOL_REF | |
1752 | && CONSTANT_POOL_ADDRESS_P (base)))) | |
1753 | return 0; | |
1754 | ||
eab5c70a | 1755 | if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode)) |
1c72c7f6 JC |
1756 | return 0; |
1757 | ||
eab5c70a BS |
1758 | x_addr = canon_rtx (x_addr); |
1759 | mem_addr = canon_rtx (mem_addr); | |
6e73e666 | 1760 | |
0211b6ab JW |
1761 | if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr, |
1762 | SIZE_FOR_MODE (x), x_addr, 0)) | |
1763 | return 0; | |
1764 | ||
c6df88cb | 1765 | if (aliases_everything_p (x)) |
0211b6ab JW |
1766 | return 1; |
1767 | ||
c6df88cb MM |
1768 | /* We cannot use aliases_everyting_p to test MEM, since we must look |
1769 | at MEM_MODE, rather than GET_MODE (MEM). */ | |
1770 | if (mem_mode == QImode || GET_CODE (mem_addr) == AND) | |
a13d4ebf AM |
1771 | return 1; |
1772 | ||
1773 | /* In true_dependence we also allow BLKmode to alias anything. Why | |
1774 | don't we do this in anti_dependence and output_dependence? */ | |
1775 | if (mem_mode == BLKmode || GET_MODE (x) == BLKmode) | |
1776 | return 1; | |
1777 | ||
1778 | return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr, | |
1779 | varies); | |
1780 | } | |
1781 | ||
1782 | /* Canonical true dependence: X is read after store in MEM takes place. | |
1783 | Variant of true_dependece which assumes MEM has already been | |
1784 | canonicalized (hence we no longer do that here). | |
1785 | The mem_addr argument has been added, since true_dependence computed | |
1786 | this value prior to canonicalizing. */ | |
1787 | ||
1788 | int | |
1789 | canon_true_dependence (mem, mem_mode, mem_addr, x, varies) | |
1790 | rtx mem, mem_addr, x; | |
1791 | enum machine_mode mem_mode; | |
1792 | int (*varies) PARAMS ((rtx, int)); | |
1793 | { | |
1794 | register rtx x_addr; | |
1795 | ||
1796 | if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) | |
1797 | return 1; | |
1798 | ||
1799 | if (DIFFERENT_ALIAS_SETS_P (x, mem)) | |
1800 | return 0; | |
1801 | ||
1802 | /* If X is an unchanging read, then it can't possibly conflict with any | |
1803 | non-unchanging store. It may conflict with an unchanging write though, | |
1804 | because there may be a single store to this address to initialize it. | |
1805 | Just fall through to the code below to resolve the case where we have | |
1806 | both an unchanging read and an unchanging write. This won't handle all | |
1807 | cases optimally, but the possible performance loss should be | |
1808 | negligible. */ | |
1809 | if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem)) | |
1810 | return 0; | |
1811 | ||
1812 | x_addr = get_addr (XEXP (x, 0)); | |
1813 | ||
1814 | if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode)) | |
1815 | return 0; | |
1816 | ||
1817 | x_addr = canon_rtx (x_addr); | |
1818 | if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr, | |
1819 | SIZE_FOR_MODE (x), x_addr, 0)) | |
1820 | return 0; | |
1821 | ||
1822 | if (aliases_everything_p (x)) | |
1823 | return 1; | |
1824 | ||
1825 | /* We cannot use aliases_everyting_p to test MEM, since we must look | |
1826 | at MEM_MODE, rather than GET_MODE (MEM). */ | |
1827 | if (mem_mode == QImode || GET_CODE (mem_addr) == AND) | |
c6df88cb | 1828 | return 1; |
0211b6ab | 1829 | |
c6df88cb MM |
1830 | /* In true_dependence we also allow BLKmode to alias anything. Why |
1831 | don't we do this in anti_dependence and output_dependence? */ | |
1832 | if (mem_mode == BLKmode || GET_MODE (x) == BLKmode) | |
1833 | return 1; | |
0211b6ab | 1834 | |
eab5c70a BS |
1835 | return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr, |
1836 | varies); | |
9ae8ffe7 JL |
1837 | } |
1838 | ||
c6df88cb MM |
1839 | /* Returns non-zero if a write to X might alias a previous read from |
1840 | (or, if WRITEP is non-zero, a write to) MEM. */ | |
9ae8ffe7 | 1841 | |
2c72b78f | 1842 | static int |
c6df88cb | 1843 | write_dependence_p (mem, x, writep) |
9ae8ffe7 JL |
1844 | rtx mem; |
1845 | rtx x; | |
c6df88cb | 1846 | int writep; |
9ae8ffe7 | 1847 | { |
6e73e666 | 1848 | rtx x_addr, mem_addr; |
c6df88cb | 1849 | rtx fixed_scalar; |
49982682 | 1850 | rtx base; |
6e73e666 | 1851 | |
9ae8ffe7 JL |
1852 | if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) |
1853 | return 1; | |
1854 | ||
eab5c70a BS |
1855 | if (DIFFERENT_ALIAS_SETS_P (x, mem)) |
1856 | return 0; | |
1857 | ||
b949ea8b JW |
1858 | /* Unchanging memory can't conflict with non-unchanging memory. */ |
1859 | if (RTX_UNCHANGING_P (x) != RTX_UNCHANGING_P (mem)) | |
1860 | return 0; | |
1861 | ||
9ae8ffe7 JL |
1862 | /* If MEM is an unchanging read, then it can't possibly conflict with |
1863 | the store to X, because there is at most one store to MEM, and it must | |
1864 | have occurred somewhere before MEM. */ | |
55efb413 JW |
1865 | if (! writep && RTX_UNCHANGING_P (mem)) |
1866 | return 0; | |
1867 | ||
1868 | x_addr = get_addr (XEXP (x, 0)); | |
1869 | mem_addr = get_addr (XEXP (mem, 0)); | |
1870 | ||
49982682 JW |
1871 | if (! writep) |
1872 | { | |
55efb413 | 1873 | base = find_base_term (mem_addr); |
49982682 JW |
1874 | if (base && (GET_CODE (base) == LABEL_REF |
1875 | || (GET_CODE (base) == SYMBOL_REF | |
1876 | && CONSTANT_POOL_ADDRESS_P (base)))) | |
1877 | return 0; | |
1878 | } | |
1879 | ||
eab5c70a BS |
1880 | if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), |
1881 | GET_MODE (mem))) | |
41472af8 MM |
1882 | return 0; |
1883 | ||
eab5c70a BS |
1884 | x_addr = canon_rtx (x_addr); |
1885 | mem_addr = canon_rtx (mem_addr); | |
6e73e666 | 1886 | |
c6df88cb MM |
1887 | if (!memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr, |
1888 | SIZE_FOR_MODE (x), x_addr, 0)) | |
1889 | return 0; | |
1890 | ||
1891 | fixed_scalar | |
eab5c70a BS |
1892 | = fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr, |
1893 | rtx_addr_varies_p); | |
1894 | ||
c6df88cb MM |
1895 | return (!(fixed_scalar == mem && !aliases_everything_p (x)) |
1896 | && !(fixed_scalar == x && !aliases_everything_p (mem))); | |
1897 | } | |
1898 | ||
1899 | /* Anti dependence: X is written after read in MEM takes place. */ | |
1900 | ||
1901 | int | |
1902 | anti_dependence (mem, x) | |
1903 | rtx mem; | |
1904 | rtx x; | |
1905 | { | |
1906 | return write_dependence_p (mem, x, /*writep=*/0); | |
9ae8ffe7 JL |
1907 | } |
1908 | ||
1909 | /* Output dependence: X is written after store in MEM takes place. */ | |
1910 | ||
1911 | int | |
1912 | output_dependence (mem, x) | |
1913 | register rtx mem; | |
1914 | register rtx x; | |
1915 | { | |
c6df88cb | 1916 | return write_dependence_p (mem, x, /*writep=*/1); |
9ae8ffe7 JL |
1917 | } |
1918 | ||
bf6d9fd7 | 1919 | /* Returns non-zero if X mentions something which is not |
7790df19 JW |
1920 | local to the function and is not constant. */ |
1921 | ||
1922 | static int | |
bf6d9fd7 | 1923 | nonlocal_mentioned_p (x) |
7790df19 JW |
1924 | rtx x; |
1925 | { | |
1926 | rtx base; | |
1927 | register RTX_CODE code; | |
1928 | int regno; | |
1929 | ||
1930 | code = GET_CODE (x); | |
1931 | ||
1932 | if (GET_RTX_CLASS (code) == 'i') | |
1933 | { | |
2a8f6b90 JH |
1934 | /* Constant functions can be constant if they don't use |
1935 | scratch memory used to mark function w/o side effects. */ | |
7790df19 | 1936 | if (code == CALL_INSN && CONST_CALL_P (x)) |
2a8f6b90 JH |
1937 | { |
1938 | x = CALL_INSN_FUNCTION_USAGE (x); | |
f8cd4126 RK |
1939 | if (x == 0) |
1940 | return 0; | |
2a8f6b90 JH |
1941 | } |
1942 | else | |
1943 | x = PATTERN (x); | |
7790df19 JW |
1944 | code = GET_CODE (x); |
1945 | } | |
1946 | ||
1947 | switch (code) | |
1948 | { | |
1949 | case SUBREG: | |
1950 | if (GET_CODE (SUBREG_REG (x)) == REG) | |
1951 | { | |
1952 | /* Global registers are not local. */ | |
1953 | if (REGNO (SUBREG_REG (x)) < FIRST_PSEUDO_REGISTER | |
ddef6bc7 | 1954 | && global_regs[subreg_regno (x)]) |
7790df19 JW |
1955 | return 1; |
1956 | return 0; | |
1957 | } | |
1958 | break; | |
1959 | ||
1960 | case REG: | |
1961 | regno = REGNO (x); | |
1962 | /* Global registers are not local. */ | |
1963 | if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno]) | |
1964 | return 1; | |
1965 | return 0; | |
1966 | ||
1967 | case SCRATCH: | |
1968 | case PC: | |
1969 | case CC0: | |
1970 | case CONST_INT: | |
1971 | case CONST_DOUBLE: | |
1972 | case CONST: | |
1973 | case LABEL_REF: | |
1974 | return 0; | |
1975 | ||
1976 | case SYMBOL_REF: | |
1977 | /* Constants in the function's constants pool are constant. */ | |
1978 | if (CONSTANT_POOL_ADDRESS_P (x)) | |
1979 | return 0; | |
1980 | return 1; | |
1981 | ||
1982 | case CALL: | |
bf6d9fd7 | 1983 | /* Non-constant calls and recursion are not local. */ |
7790df19 JW |
1984 | return 1; |
1985 | ||
1986 | case MEM: | |
1987 | /* Be overly conservative and consider any volatile memory | |
1988 | reference as not local. */ | |
1989 | if (MEM_VOLATILE_P (x)) | |
1990 | return 1; | |
1991 | base = find_base_term (XEXP (x, 0)); | |
1992 | if (base) | |
1993 | { | |
b3b5ad95 JL |
1994 | /* A Pmode ADDRESS could be a reference via the structure value |
1995 | address or static chain. Such memory references are nonlocal. | |
1996 | ||
1997 | Thus, we have to examine the contents of the ADDRESS to find | |
1998 | out if this is a local reference or not. */ | |
1999 | if (GET_CODE (base) == ADDRESS | |
2000 | && GET_MODE (base) == Pmode | |
2001 | && (XEXP (base, 0) == stack_pointer_rtx | |
2002 | || XEXP (base, 0) == arg_pointer_rtx | |
2003 | #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
2004 | || XEXP (base, 0) == hard_frame_pointer_rtx | |
2005 | #endif | |
2006 | || XEXP (base, 0) == frame_pointer_rtx)) | |
7790df19 JW |
2007 | return 0; |
2008 | /* Constants in the function's constant pool are constant. */ | |
2009 | if (GET_CODE (base) == SYMBOL_REF && CONSTANT_POOL_ADDRESS_P (base)) | |
2010 | return 0; | |
2011 | } | |
2012 | return 1; | |
2013 | ||
bf6d9fd7 | 2014 | case UNSPEC_VOLATILE: |
7790df19 | 2015 | case ASM_INPUT: |
7790df19 JW |
2016 | return 1; |
2017 | ||
bf6d9fd7 JW |
2018 | case ASM_OPERANDS: |
2019 | if (MEM_VOLATILE_P (x)) | |
2020 | return 1; | |
2021 | ||
2022 | /* FALLTHROUGH */ | |
2023 | ||
7790df19 JW |
2024 | default: |
2025 | break; | |
2026 | } | |
2027 | ||
2028 | /* Recursively scan the operands of this expression. */ | |
2029 | ||
2030 | { | |
499b1098 | 2031 | register const char *fmt = GET_RTX_FORMAT (code); |
7790df19 JW |
2032 | register int i; |
2033 | ||
2034 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
2035 | { | |
2a8f6b90 | 2036 | if (fmt[i] == 'e' && XEXP (x, i)) |
7790df19 | 2037 | { |
bf6d9fd7 | 2038 | if (nonlocal_mentioned_p (XEXP (x, i))) |
7790df19 JW |
2039 | return 1; |
2040 | } | |
d4757e6a | 2041 | else if (fmt[i] == 'E') |
7790df19 JW |
2042 | { |
2043 | register int j; | |
2044 | for (j = 0; j < XVECLEN (x, i); j++) | |
bf6d9fd7 | 2045 | if (nonlocal_mentioned_p (XVECEXP (x, i, j))) |
7790df19 JW |
2046 | return 1; |
2047 | } | |
2048 | } | |
2049 | } | |
2050 | ||
2051 | return 0; | |
2052 | } | |
2053 | ||
e004f2f7 JW |
2054 | /* Return non-zero if a loop (natural or otherwise) is present. |
2055 | Inspired by Depth_First_Search_PP described in: | |
2056 | ||
2057 | Advanced Compiler Design and Implementation | |
2058 | Steven Muchnick | |
2059 | Morgan Kaufmann, 1997 | |
2060 | ||
2061 | and heavily borrowed from flow_depth_first_order_compute. */ | |
2062 | ||
2063 | static int | |
2064 | loop_p () | |
2065 | { | |
2066 | edge *stack; | |
2067 | int *pre; | |
2068 | int *post; | |
2069 | int sp; | |
2070 | int prenum = 1; | |
2071 | int postnum = 1; | |
2072 | sbitmap visited; | |
2073 | ||
2074 | /* Allocate the preorder and postorder number arrays. */ | |
2075 | pre = (int *) xcalloc (n_basic_blocks, sizeof (int)); | |
2076 | post = (int *) xcalloc (n_basic_blocks, sizeof (int)); | |
2077 | ||
2078 | /* Allocate stack for back-tracking up CFG. */ | |
2079 | stack = (edge *) xmalloc ((n_basic_blocks + 1) * sizeof (edge)); | |
2080 | sp = 0; | |
2081 | ||
2082 | /* Allocate bitmap to track nodes that have been visited. */ | |
2083 | visited = sbitmap_alloc (n_basic_blocks); | |
2084 | ||
2085 | /* None of the nodes in the CFG have been visited yet. */ | |
2086 | sbitmap_zero (visited); | |
2087 | ||
2088 | /* Push the first edge on to the stack. */ | |
2089 | stack[sp++] = ENTRY_BLOCK_PTR->succ; | |
2090 | ||
2091 | while (sp) | |
2092 | { | |
2093 | edge e; | |
2094 | basic_block src; | |
2095 | basic_block dest; | |
2096 | ||
2097 | /* Look at the edge on the top of the stack. */ | |
2098 | e = stack[sp - 1]; | |
2099 | src = e->src; | |
2100 | dest = e->dest; | |
2101 | ||
2102 | /* Check if the edge destination has been visited yet. */ | |
2103 | if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index)) | |
2104 | { | |
2105 | /* Mark that we have visited the destination. */ | |
2106 | SET_BIT (visited, dest->index); | |
2107 | ||
2108 | pre[dest->index] = prenum++; | |
2109 | ||
2110 | if (dest->succ) | |
2111 | { | |
2112 | /* Since the DEST node has been visited for the first | |
2113 | time, check its successors. */ | |
2114 | stack[sp++] = dest->succ; | |
2115 | } | |
2116 | else | |
2117 | post[dest->index] = postnum++; | |
2118 | } | |
2119 | else | |
2120 | { | |
d69d0316 | 2121 | if (dest != EXIT_BLOCK_PTR && src != ENTRY_BLOCK_PTR |
e004f2f7 JW |
2122 | && pre[src->index] >= pre[dest->index] |
2123 | && post[dest->index] == 0) | |
2124 | break; | |
2125 | ||
2126 | if (! e->succ_next && src != ENTRY_BLOCK_PTR) | |
2127 | post[src->index] = postnum++; | |
2128 | ||
2129 | if (e->succ_next) | |
2130 | stack[sp - 1] = e->succ_next; | |
2131 | else | |
2132 | sp--; | |
2133 | } | |
2134 | } | |
2135 | ||
2136 | free (pre); | |
2137 | free (post); | |
2138 | free (stack); | |
2139 | sbitmap_free (visited); | |
2140 | ||
2141 | return sp; | |
2142 | } | |
2143 | ||
7790df19 JW |
2144 | /* Mark the function if it is constant. */ |
2145 | ||
2146 | void | |
2147 | mark_constant_function () | |
2148 | { | |
2149 | rtx insn; | |
bf6d9fd7 | 2150 | int nonlocal_mentioned; |
7790df19 JW |
2151 | |
2152 | if (TREE_PUBLIC (current_function_decl) | |
2153 | || TREE_READONLY (current_function_decl) | |
bf6d9fd7 | 2154 | || DECL_IS_PURE (current_function_decl) |
7790df19 JW |
2155 | || TREE_THIS_VOLATILE (current_function_decl) |
2156 | || TYPE_MODE (TREE_TYPE (current_function_decl)) == VOIDmode) | |
2157 | return; | |
2158 | ||
e004f2f7 JW |
2159 | /* A loop might not return which counts as a side effect. */ |
2160 | if (loop_p ()) | |
2161 | return; | |
2162 | ||
bf6d9fd7 JW |
2163 | nonlocal_mentioned = 0; |
2164 | ||
2165 | init_alias_analysis (); | |
2166 | ||
7790df19 JW |
2167 | /* Determine if this is a constant function. */ |
2168 | ||
2169 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) | |
bf6d9fd7 JW |
2170 | if (INSN_P (insn) && nonlocal_mentioned_p (insn)) |
2171 | { | |
2172 | nonlocal_mentioned = 1; | |
2173 | break; | |
2174 | } | |
2175 | ||
2176 | end_alias_analysis (); | |
7790df19 JW |
2177 | |
2178 | /* Mark the function. */ | |
2179 | ||
bf6d9fd7 JW |
2180 | if (! nonlocal_mentioned) |
2181 | TREE_READONLY (current_function_decl) = 1; | |
7790df19 JW |
2182 | } |
2183 | ||
6e73e666 JC |
2184 | |
2185 | static HARD_REG_SET argument_registers; | |
2186 | ||
2187 | void | |
2188 | init_alias_once () | |
2189 | { | |
2190 | register int i; | |
2191 | ||
2192 | #ifndef OUTGOING_REGNO | |
2193 | #define OUTGOING_REGNO(N) N | |
2194 | #endif | |
2195 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
2196 | /* Check whether this register can hold an incoming pointer | |
2197 | argument. FUNCTION_ARG_REGNO_P tests outgoing register | |
2198 | numbers, so translate if necessary due to register windows. */ | |
2199 | if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i)) | |
2200 | && HARD_REGNO_MODE_OK (i, Pmode)) | |
2201 | SET_HARD_REG_BIT (argument_registers, i); | |
3932261a | 2202 | |
30f72379 | 2203 | alias_sets = splay_tree_new (splay_tree_compare_ints, 0, 0); |
6e73e666 JC |
2204 | } |
2205 | ||
c13e8210 MM |
2206 | /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE |
2207 | array. */ | |
2208 | ||
9ae8ffe7 JL |
2209 | void |
2210 | init_alias_analysis () | |
2211 | { | |
2212 | int maxreg = max_reg_num (); | |
ea64ef27 | 2213 | int changed, pass; |
9ae8ffe7 | 2214 | register int i; |
e51712db | 2215 | register unsigned int ui; |
9ae8ffe7 | 2216 | register rtx insn; |
9ae8ffe7 JL |
2217 | |
2218 | reg_known_value_size = maxreg; | |
2219 | ||
e05e2395 MM |
2220 | reg_known_value |
2221 | = (rtx *) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (rtx)) | |
2222 | - FIRST_PSEUDO_REGISTER; | |
2223 | reg_known_equiv_p | |
2224 | = (char*) xcalloc ((maxreg - FIRST_PSEUDO_REGISTER), sizeof (char)) | |
9ae8ffe7 | 2225 | - FIRST_PSEUDO_REGISTER; |
9ae8ffe7 | 2226 | |
6e73e666 JC |
2227 | /* Overallocate reg_base_value to allow some growth during loop |
2228 | optimization. Loop unrolling can create a large number of | |
2229 | registers. */ | |
2230 | reg_base_value_size = maxreg * 2; | |
ac606739 | 2231 | reg_base_value = (rtx *) xcalloc (reg_base_value_size, sizeof (rtx)); |
1f8f4a0b | 2232 | ggc_add_rtx_root (reg_base_value, reg_base_value_size); |
ac606739 | 2233 | |
e05e2395 MM |
2234 | new_reg_base_value = (rtx *) xmalloc (reg_base_value_size * sizeof (rtx)); |
2235 | reg_seen = (char *) xmalloc (reg_base_value_size); | |
de12be17 JC |
2236 | if (! reload_completed && flag_unroll_loops) |
2237 | { | |
ac606739 | 2238 | /* ??? Why are we realloc'ing if we're just going to zero it? */ |
de12be17 JC |
2239 | alias_invariant = (rtx *)xrealloc (alias_invariant, |
2240 | reg_base_value_size * sizeof (rtx)); | |
961192e1 | 2241 | memset ((char *)alias_invariant, 0, reg_base_value_size * sizeof (rtx)); |
de12be17 | 2242 | } |
ec907dd8 JL |
2243 | |
2244 | /* The basic idea is that each pass through this loop will use the | |
2245 | "constant" information from the previous pass to propagate alias | |
2246 | information through another level of assignments. | |
2247 | ||
2248 | This could get expensive if the assignment chains are long. Maybe | |
2249 | we should throttle the number of iterations, possibly based on | |
6e73e666 | 2250 | the optimization level or flag_expensive_optimizations. |
ec907dd8 JL |
2251 | |
2252 | We could propagate more information in the first pass by making use | |
2253 | of REG_N_SETS to determine immediately that the alias information | |
ea64ef27 JL |
2254 | for a pseudo is "constant". |
2255 | ||
2256 | A program with an uninitialized variable can cause an infinite loop | |
2257 | here. Instead of doing a full dataflow analysis to detect such problems | |
2258 | we just cap the number of iterations for the loop. | |
2259 | ||
2260 | The state of the arrays for the set chain in question does not matter | |
2261 | since the program has undefined behavior. */ | |
6e73e666 | 2262 | |
ea64ef27 | 2263 | pass = 0; |
6e73e666 | 2264 | do |
ec907dd8 JL |
2265 | { |
2266 | /* Assume nothing will change this iteration of the loop. */ | |
2267 | changed = 0; | |
2268 | ||
ec907dd8 JL |
2269 | /* We want to assign the same IDs each iteration of this loop, so |
2270 | start counting from zero each iteration of the loop. */ | |
2271 | unique_id = 0; | |
2272 | ||
2273 | /* We're at the start of the funtion each iteration through the | |
2274 | loop, so we're copying arguments. */ | |
2275 | copying_arguments = 1; | |
9ae8ffe7 | 2276 | |
6e73e666 | 2277 | /* Wipe the potential alias information clean for this pass. */ |
961192e1 | 2278 | memset ((char *) new_reg_base_value, 0, reg_base_value_size * sizeof (rtx)); |
8072f69c | 2279 | |
6e73e666 | 2280 | /* Wipe the reg_seen array clean. */ |
961192e1 | 2281 | memset ((char *) reg_seen, 0, reg_base_value_size); |
9ae8ffe7 | 2282 | |
6e73e666 JC |
2283 | /* Mark all hard registers which may contain an address. |
2284 | The stack, frame and argument pointers may contain an address. | |
2285 | An argument register which can hold a Pmode value may contain | |
2286 | an address even if it is not in BASE_REGS. | |
8072f69c | 2287 | |
6e73e666 JC |
2288 | The address expression is VOIDmode for an argument and |
2289 | Pmode for other registers. */ | |
2290 | ||
2291 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
2292 | if (TEST_HARD_REG_BIT (argument_registers, i)) | |
38a448ca RH |
2293 | new_reg_base_value[i] = gen_rtx_ADDRESS (VOIDmode, |
2294 | gen_rtx_REG (Pmode, i)); | |
6e73e666 JC |
2295 | |
2296 | new_reg_base_value[STACK_POINTER_REGNUM] | |
38a448ca | 2297 | = gen_rtx_ADDRESS (Pmode, stack_pointer_rtx); |
6e73e666 | 2298 | new_reg_base_value[ARG_POINTER_REGNUM] |
38a448ca | 2299 | = gen_rtx_ADDRESS (Pmode, arg_pointer_rtx); |
6e73e666 | 2300 | new_reg_base_value[FRAME_POINTER_REGNUM] |
38a448ca | 2301 | = gen_rtx_ADDRESS (Pmode, frame_pointer_rtx); |
2a2c8203 | 2302 | #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM |
6e73e666 | 2303 | new_reg_base_value[HARD_FRAME_POINTER_REGNUM] |
38a448ca | 2304 | = gen_rtx_ADDRESS (Pmode, hard_frame_pointer_rtx); |
2a2c8203 | 2305 | #endif |
ec907dd8 JL |
2306 | |
2307 | /* Walk the insns adding values to the new_reg_base_value array. */ | |
2308 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) | |
9ae8ffe7 | 2309 | { |
2c3c49de | 2310 | if (INSN_P (insn)) |
ec907dd8 | 2311 | { |
6e73e666 | 2312 | rtx note, set; |
efc9bd41 RK |
2313 | |
2314 | #if defined (HAVE_prologue) || defined (HAVE_epilogue) | |
657959ca JL |
2315 | /* The prologue/epilouge insns are not threaded onto the |
2316 | insn chain until after reload has completed. Thus, | |
2317 | there is no sense wasting time checking if INSN is in | |
2318 | the prologue/epilogue until after reload has completed. */ | |
2319 | if (reload_completed | |
2320 | && prologue_epilogue_contains (insn)) | |
efc9bd41 RK |
2321 | continue; |
2322 | #endif | |
2323 | ||
ec907dd8 JL |
2324 | /* If this insn has a noalias note, process it, Otherwise, |
2325 | scan for sets. A simple set will have no side effects | |
2326 | which could change the base value of any other register. */ | |
6e73e666 | 2327 | |
ec907dd8 | 2328 | if (GET_CODE (PATTERN (insn)) == SET |
efc9bd41 RK |
2329 | && REG_NOTES (insn) != 0 |
2330 | && find_reg_note (insn, REG_NOALIAS, NULL_RTX)) | |
84832317 | 2331 | record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL); |
ec907dd8 | 2332 | else |
84832317 | 2333 | note_stores (PATTERN (insn), record_set, NULL); |
6e73e666 JC |
2334 | |
2335 | set = single_set (insn); | |
2336 | ||
2337 | if (set != 0 | |
2338 | && GET_CODE (SET_DEST (set)) == REG | |
fb6754f0 | 2339 | && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER) |
6e73e666 | 2340 | { |
fb6754f0 | 2341 | unsigned int regno = REGNO (SET_DEST (set)); |
713f41f9 BS |
2342 | rtx src = SET_SRC (set); |
2343 | ||
2344 | if (REG_NOTES (insn) != 0 | |
2345 | && (((note = find_reg_note (insn, REG_EQUAL, 0)) != 0 | |
2346 | && REG_N_SETS (regno) == 1) | |
2347 | || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != 0) | |
2348 | && GET_CODE (XEXP (note, 0)) != EXPR_LIST | |
bb2cf916 | 2349 | && ! rtx_varies_p (XEXP (note, 0), 1) |
713f41f9 BS |
2350 | && ! reg_overlap_mentioned_p (SET_DEST (set), XEXP (note, 0))) |
2351 | { | |
2352 | reg_known_value[regno] = XEXP (note, 0); | |
2353 | reg_known_equiv_p[regno] = REG_NOTE_KIND (note) == REG_EQUIV; | |
2354 | } | |
2355 | else if (REG_N_SETS (regno) == 1 | |
2356 | && GET_CODE (src) == PLUS | |
2357 | && GET_CODE (XEXP (src, 0)) == REG | |
fb6754f0 BS |
2358 | && REGNO (XEXP (src, 0)) >= FIRST_PSEUDO_REGISTER |
2359 | && (reg_known_value[REGNO (XEXP (src, 0))]) | |
713f41f9 BS |
2360 | && GET_CODE (XEXP (src, 1)) == CONST_INT) |
2361 | { | |
2362 | rtx op0 = XEXP (src, 0); | |
bb2cf916 | 2363 | op0 = reg_known_value[REGNO (op0)]; |
713f41f9 | 2364 | reg_known_value[regno] |
ed8908e7 | 2365 | = plus_constant (op0, INTVAL (XEXP (src, 1))); |
713f41f9 BS |
2366 | reg_known_equiv_p[regno] = 0; |
2367 | } | |
2368 | else if (REG_N_SETS (regno) == 1 | |
2369 | && ! rtx_varies_p (src, 1)) | |
2370 | { | |
2371 | reg_known_value[regno] = src; | |
2372 | reg_known_equiv_p[regno] = 0; | |
2373 | } | |
6e73e666 | 2374 | } |
ec907dd8 JL |
2375 | } |
2376 | else if (GET_CODE (insn) == NOTE | |
2377 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG) | |
2378 | copying_arguments = 0; | |
6e73e666 | 2379 | } |
ec907dd8 | 2380 | |
6e73e666 | 2381 | /* Now propagate values from new_reg_base_value to reg_base_value. */ |
e51712db | 2382 | for (ui = 0; ui < reg_base_value_size; ui++) |
6e73e666 | 2383 | { |
e51712db KG |
2384 | if (new_reg_base_value[ui] |
2385 | && new_reg_base_value[ui] != reg_base_value[ui] | |
2386 | && ! rtx_equal_p (new_reg_base_value[ui], reg_base_value[ui])) | |
ec907dd8 | 2387 | { |
e51712db | 2388 | reg_base_value[ui] = new_reg_base_value[ui]; |
6e73e666 | 2389 | changed = 1; |
ec907dd8 | 2390 | } |
9ae8ffe7 | 2391 | } |
9ae8ffe7 | 2392 | } |
6e73e666 | 2393 | while (changed && ++pass < MAX_ALIAS_LOOP_PASSES); |
9ae8ffe7 JL |
2394 | |
2395 | /* Fill in the remaining entries. */ | |
2396 | for (i = FIRST_PSEUDO_REGISTER; i < maxreg; i++) | |
2397 | if (reg_known_value[i] == 0) | |
2398 | reg_known_value[i] = regno_reg_rtx[i]; | |
2399 | ||
9ae8ffe7 JL |
2400 | /* Simplify the reg_base_value array so that no register refers to |
2401 | another register, except to special registers indirectly through | |
2402 | ADDRESS expressions. | |
2403 | ||
2404 | In theory this loop can take as long as O(registers^2), but unless | |
2405 | there are very long dependency chains it will run in close to linear | |
ea64ef27 JL |
2406 | time. |
2407 | ||
2408 | This loop may not be needed any longer now that the main loop does | |
2409 | a better job at propagating alias information. */ | |
2410 | pass = 0; | |
9ae8ffe7 JL |
2411 | do |
2412 | { | |
2413 | changed = 0; | |
ea64ef27 | 2414 | pass++; |
e51712db | 2415 | for (ui = 0; ui < reg_base_value_size; ui++) |
9ae8ffe7 | 2416 | { |
e51712db | 2417 | rtx base = reg_base_value[ui]; |
9ae8ffe7 JL |
2418 | if (base && GET_CODE (base) == REG) |
2419 | { | |
fb6754f0 | 2420 | unsigned int base_regno = REGNO (base); |
e51712db KG |
2421 | if (base_regno == ui) /* register set from itself */ |
2422 | reg_base_value[ui] = 0; | |
9ae8ffe7 | 2423 | else |
e51712db | 2424 | reg_base_value[ui] = reg_base_value[base_regno]; |
9ae8ffe7 JL |
2425 | changed = 1; |
2426 | } | |
2427 | } | |
2428 | } | |
ea64ef27 | 2429 | while (changed && pass < MAX_ALIAS_LOOP_PASSES); |
9ae8ffe7 | 2430 | |
e05e2395 MM |
2431 | /* Clean up. */ |
2432 | free (new_reg_base_value); | |
ec907dd8 | 2433 | new_reg_base_value = 0; |
e05e2395 | 2434 | free (reg_seen); |
9ae8ffe7 JL |
2435 | reg_seen = 0; |
2436 | } | |
2437 | ||
2438 | void | |
2439 | end_alias_analysis () | |
2440 | { | |
e05e2395 | 2441 | free (reg_known_value + FIRST_PSEUDO_REGISTER); |
9ae8ffe7 | 2442 | reg_known_value = 0; |
ac606739 | 2443 | reg_known_value_size = 0; |
e05e2395 MM |
2444 | free (reg_known_equiv_p + FIRST_PSEUDO_REGISTER); |
2445 | reg_known_equiv_p = 0; | |
ac606739 GS |
2446 | if (reg_base_value) |
2447 | { | |
1f8f4a0b | 2448 | ggc_del_root (reg_base_value); |
ac606739 GS |
2449 | free (reg_base_value); |
2450 | reg_base_value = 0; | |
2451 | } | |
9ae8ffe7 | 2452 | reg_base_value_size = 0; |
de12be17 JC |
2453 | if (alias_invariant) |
2454 | { | |
ac606739 | 2455 | free (alias_invariant); |
de12be17 JC |
2456 | alias_invariant = 0; |
2457 | } | |
9ae8ffe7 | 2458 | } |