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9ae8ffe7 | 1 | /* Alias analysis for GNU C |
41af4023 | 2 | Copyright (C) 1997, 1998, 1999 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 JL |
24 | #include "rtl.h" |
25 | #include "expr.h" | |
26 | #include "regs.h" | |
27 | #include "hard-reg-set.h" | |
28 | #include "flags.h" | |
264fac34 | 29 | #include "output.h" |
2e107e9e | 30 | #include "toplev.h" |
3932261a MM |
31 | #include "splay-tree.h" |
32 | ||
33 | /* The alias sets assigned to MEMs assist the back-end in determining | |
34 | which MEMs can alias which other MEMs. In general, two MEMs in | |
35 | different alias sets to not alias each other. There is one | |
36 | exception, however. Consider something like: | |
37 | ||
38 | struct S {int i; double d; }; | |
39 | ||
40 | a store to an `S' can alias something of either type `int' or type | |
41 | `double'. (However, a store to an `int' cannot alias a `double' | |
42 | and vice versa.) We indicate this via a tree structure that looks | |
43 | like: | |
44 | struct S | |
45 | / \ | |
46 | / \ | |
47 | |/_ _\| | |
48 | int double | |
49 | ||
50 | (The arrows are directed and point downwards.) If, when comparing | |
51 | two alias sets, we can hold one set fixed, and trace the other set | |
52 | downwards, and at some point find the first set, the two MEMs can | |
53 | alias one another. In this situation we say the alias set for | |
54 | `struct S' is the `superset' and that those for `int' and `double' | |
55 | are `subsets'. | |
56 | ||
57 | Alias set zero is implicitly a superset of all other alias sets. | |
58 | However, this is no actual entry for alias set zero. It is an | |
59 | error to attempt to explicitly construct a subset of zero. */ | |
60 | ||
61 | typedef struct alias_set_entry { | |
62 | /* The alias set number, as stored in MEM_ALIAS_SET. */ | |
63 | int alias_set; | |
64 | ||
65 | /* The children of the alias set. These are not just the immediate | |
66 | children, but, in fact, all children. So, if we have: | |
67 | ||
68 | struct T { struct S s; float f; } | |
69 | ||
70 | continuing our example above, the children here will be all of | |
71 | `int', `double', `float', and `struct S'. */ | |
72 | splay_tree children; | |
73 | }* alias_set_entry; | |
9ae8ffe7 JL |
74 | |
75 | static rtx canon_rtx PROTO((rtx)); | |
76 | static int rtx_equal_for_memref_p PROTO((rtx, rtx)); | |
77 | static rtx find_symbolic_term PROTO((rtx)); | |
78 | static int memrefs_conflict_p PROTO((int, rtx, int, rtx, | |
79 | HOST_WIDE_INT)); | |
70fec650 JL |
80 | static void record_set PROTO((rtx, rtx)); |
81 | static rtx find_base_term PROTO((rtx)); | |
56ee9281 RH |
82 | static int base_alias_check PROTO((rtx, rtx, enum machine_mode, |
83 | enum machine_mode)); | |
960b4ee6 | 84 | static rtx find_base_value PROTO((rtx)); |
3932261a MM |
85 | static int mems_in_disjoint_alias_sets_p PROTO((rtx, rtx)); |
86 | static int alias_set_compare PROTO((splay_tree_key, | |
87 | splay_tree_key)); | |
88 | static int insert_subset_children PROTO((splay_tree_node, | |
89 | void*)); | |
90 | static alias_set_entry get_alias_set_entry PROTO((int)); | |
c6df88cb MM |
91 | static rtx fixed_scalar_and_varying_struct_p PROTO((rtx, rtx, int (*)(rtx))); |
92 | static int aliases_everything_p PROTO((rtx)); | |
93 | static int write_dependence_p PROTO((rtx, rtx, int)); | |
9ae8ffe7 JL |
94 | |
95 | /* Set up all info needed to perform alias analysis on memory references. */ | |
96 | ||
97 | #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X))) | |
98 | ||
41472af8 | 99 | /* Returns nonzero if MEM1 and MEM2 do not alias because they are in |
264fac34 MM |
100 | different alias sets. We ignore alias sets in functions making use |
101 | of variable arguments because the va_arg macros on some systems are | |
102 | not legal ANSI C. */ | |
103 | #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \ | |
3932261a | 104 | mems_in_disjoint_alias_sets_p (MEM1, MEM2) |
41472af8 | 105 | |
ea64ef27 JL |
106 | /* Cap the number of passes we make over the insns propagating alias |
107 | information through set chains. | |
108 | ||
109 | 10 is a completely arbitrary choice. */ | |
110 | #define MAX_ALIAS_LOOP_PASSES 10 | |
111 | ||
9ae8ffe7 JL |
112 | /* reg_base_value[N] gives an address to which register N is related. |
113 | If all sets after the first add or subtract to the current value | |
114 | or otherwise modify it so it does not point to a different top level | |
115 | object, reg_base_value[N] is equal to the address part of the source | |
2a2c8203 JC |
116 | of the first set. |
117 | ||
118 | A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS | |
119 | expressions represent certain special values: function arguments and | |
120 | the stack, frame, and argument pointers. The contents of an address | |
121 | expression are not used (but they are descriptive for debugging); | |
122 | only the address and mode matter. Pointer equality, not rtx_equal_p, | |
123 | determines whether two ADDRESS expressions refer to the same base | |
124 | address. The mode determines whether it is a function argument or | |
125 | other special value. */ | |
126 | ||
9ae8ffe7 | 127 | rtx *reg_base_value; |
ec907dd8 | 128 | rtx *new_reg_base_value; |
9ae8ffe7 JL |
129 | unsigned int reg_base_value_size; /* size of reg_base_value array */ |
130 | #define REG_BASE_VALUE(X) \ | |
e51712db | 131 | ((unsigned) REGNO (X) < reg_base_value_size ? reg_base_value[REGNO (X)] : 0) |
9ae8ffe7 | 132 | |
de12be17 JC |
133 | /* Vector of known invariant relationships between registers. Set in |
134 | loop unrolling. Indexed by register number, if nonzero the value | |
135 | is an expression describing this register in terms of another. | |
136 | ||
137 | The length of this array is REG_BASE_VALUE_SIZE. | |
138 | ||
139 | Because this array contains only pseudo registers it has no effect | |
140 | after reload. */ | |
141 | static rtx *alias_invariant; | |
142 | ||
9ae8ffe7 JL |
143 | /* Vector indexed by N giving the initial (unchanging) value known |
144 | for pseudo-register N. */ | |
145 | rtx *reg_known_value; | |
146 | ||
147 | /* Indicates number of valid entries in reg_known_value. */ | |
148 | static int reg_known_value_size; | |
149 | ||
150 | /* Vector recording for each reg_known_value whether it is due to a | |
151 | REG_EQUIV note. Future passes (viz., reload) may replace the | |
152 | pseudo with the equivalent expression and so we account for the | |
153 | dependences that would be introduced if that happens. */ | |
154 | /* ??? This is a problem only on the Convex. The REG_EQUIV notes created in | |
155 | assign_parms mention the arg pointer, and there are explicit insns in the | |
156 | RTL that modify the arg pointer. Thus we must ensure that such insns don't | |
157 | get scheduled across each other because that would invalidate the REG_EQUIV | |
158 | notes. One could argue that the REG_EQUIV notes are wrong, but solving | |
159 | the problem in the scheduler will likely give better code, so we do it | |
160 | here. */ | |
161 | char *reg_known_equiv_p; | |
162 | ||
2a2c8203 JC |
163 | /* True when scanning insns from the start of the rtl to the |
164 | NOTE_INSN_FUNCTION_BEG note. */ | |
9ae8ffe7 | 165 | |
9ae8ffe7 JL |
166 | static int copying_arguments; |
167 | ||
3932261a MM |
168 | /* The splay-tree used to store the various alias set entries. */ |
169 | ||
170 | static splay_tree alias_sets; | |
171 | ||
172 | /* Returns -1, 0, 1 according to whether SET1 is less than, equal to, | |
173 | or greater than SET2. */ | |
174 | ||
175 | static int | |
176 | alias_set_compare (set1, set2) | |
177 | splay_tree_key set1; | |
178 | splay_tree_key set2; | |
179 | { | |
180 | int s1 = (int) set1; | |
181 | int s2 = (int) set2; | |
182 | ||
183 | if (s1 < s2) | |
184 | return -1; | |
185 | else if (s1 > s2) | |
186 | return 1; | |
187 | else | |
188 | return 0; | |
189 | } | |
190 | ||
191 | /* Returns a pointer to the alias set entry for ALIAS_SET, if there is | |
192 | such an entry, or NULL otherwise. */ | |
193 | ||
194 | static alias_set_entry | |
195 | get_alias_set_entry (alias_set) | |
196 | int alias_set; | |
197 | { | |
198 | splay_tree_node sn = | |
199 | splay_tree_lookup (alias_sets, (splay_tree_key) alias_set); | |
200 | ||
201 | return sn ? ((alias_set_entry) sn->value) : ((alias_set_entry) 0); | |
202 | } | |
203 | ||
204 | /* Returns nonzero value if the alias sets for MEM1 and MEM2 are such | |
205 | that the two MEMs cannot alias each other. */ | |
206 | ||
207 | static int | |
208 | mems_in_disjoint_alias_sets_p (mem1, mem2) | |
209 | rtx mem1; | |
210 | rtx mem2; | |
211 | { | |
212 | alias_set_entry ase; | |
213 | ||
214 | #ifdef ENABLE_CHECKING | |
215 | /* Perform a basic sanity check. Namely, that there are no alias sets | |
216 | if we're not using strict aliasing. This helps to catch bugs | |
217 | whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or | |
218 | where a MEM is allocated in some way other than by the use of | |
219 | gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to | |
220 | use alias sets to indicate that spilled registers cannot alias each | |
221 | other, we might need to remove this check. */ | |
222 | if (!flag_strict_aliasing && | |
223 | (MEM_ALIAS_SET (mem1) || MEM_ALIAS_SET (mem2))) | |
224 | abort (); | |
225 | #endif | |
226 | ||
227 | /* The code used in varargs macros are often not conforming ANSI C, | |
228 | which can trick the compiler into making incorrect aliasing | |
229 | assumptions in these functions. So, we don't use alias sets in | |
230 | such a function. FIXME: This should be moved into the front-end; | |
231 | it is a language-dependent notion, and there's no reason not to | |
232 | still use these checks to handle globals. */ | |
233 | if (current_function_stdarg || current_function_varargs) | |
234 | return 0; | |
235 | ||
236 | if (!MEM_ALIAS_SET (mem1) || !MEM_ALIAS_SET (mem2)) | |
237 | /* We have no alias set information for one of the MEMs, so we | |
238 | have to assume it can alias anything. */ | |
239 | return 0; | |
240 | ||
241 | if (MEM_ALIAS_SET (mem1) == MEM_ALIAS_SET (mem2)) | |
242 | /* The two alias sets are the same, so they may alias. */ | |
243 | return 0; | |
244 | ||
245 | /* Iterate through each of the children of the first alias set, | |
246 | comparing it with the second alias set. */ | |
247 | ase = get_alias_set_entry (MEM_ALIAS_SET (mem1)); | |
248 | if (ase && splay_tree_lookup (ase->children, | |
249 | (splay_tree_key) MEM_ALIAS_SET (mem2))) | |
250 | return 0; | |
251 | ||
252 | /* Now do the same, but with the alias sets reversed. */ | |
253 | ase = get_alias_set_entry (MEM_ALIAS_SET (mem2)); | |
254 | if (ase && splay_tree_lookup (ase->children, | |
255 | (splay_tree_key) MEM_ALIAS_SET (mem1))) | |
256 | return 0; | |
257 | ||
258 | /* The two MEMs are in distinct alias sets, and neither one is the | |
259 | child of the other. Therefore, they cannot alias. */ | |
260 | return 1; | |
261 | } | |
262 | ||
263 | /* Insert the NODE into the splay tree given by DATA. Used by | |
264 | record_alias_subset via splay_tree_foreach. */ | |
265 | ||
266 | static int | |
267 | insert_subset_children (node, data) | |
268 | splay_tree_node node; | |
269 | void *data; | |
270 | { | |
271 | splay_tree_insert ((splay_tree) data, | |
272 | node->key, | |
273 | node->value); | |
274 | ||
275 | return 0; | |
276 | } | |
277 | ||
278 | /* Indicate that things in SUBSET can alias things in SUPERSET, but | |
279 | not vice versa. For example, in C, a store to an `int' can alias a | |
280 | structure containing an `int', but not vice versa. Here, the | |
281 | structure would be the SUPERSET and `int' the SUBSET. This | |
282 | function should be called only once per SUPERSET/SUBSET pair. At | |
283 | present any given alias set may only be a subset of one superset. | |
284 | ||
285 | It is illegal for SUPERSET to be zero; everything is implicitly a | |
286 | subset of alias set zero. */ | |
287 | ||
288 | void | |
289 | record_alias_subset (superset, subset) | |
290 | int superset; | |
291 | int subset; | |
292 | { | |
293 | alias_set_entry superset_entry; | |
294 | alias_set_entry subset_entry; | |
295 | ||
296 | if (superset == 0) | |
297 | abort (); | |
298 | ||
299 | superset_entry = get_alias_set_entry (superset); | |
300 | if (!superset_entry) | |
301 | { | |
302 | /* Create an entry for the SUPERSET, so that we have a place to | |
303 | attach the SUBSET. */ | |
304 | superset_entry = | |
305 | (alias_set_entry) xmalloc (sizeof (struct alias_set_entry)); | |
306 | superset_entry->alias_set = superset; | |
307 | superset_entry->children | |
973838fd | 308 | = splay_tree_new (alias_set_compare, 0, 0); |
3932261a MM |
309 | splay_tree_insert (alias_sets, |
310 | (splay_tree_key) superset, | |
311 | (splay_tree_value) superset_entry); | |
312 | ||
313 | } | |
314 | ||
315 | subset_entry = get_alias_set_entry (subset); | |
316 | if (subset_entry) | |
317 | /* There is an entry for the subset. Enter all of its children | |
318 | (if they are not already present) as children of the SUPERSET. */ | |
319 | splay_tree_foreach (subset_entry->children, | |
973838fd | 320 | insert_subset_children, |
3932261a MM |
321 | superset_entry->children); |
322 | ||
323 | /* Enter the SUBSET itself as a child of the SUPERSET. */ | |
324 | splay_tree_insert (superset_entry->children, | |
325 | (splay_tree_key) subset, | |
326 | /*value=*/0); | |
327 | } | |
328 | ||
2a2c8203 JC |
329 | /* Inside SRC, the source of a SET, find a base address. */ |
330 | ||
9ae8ffe7 JL |
331 | static rtx |
332 | find_base_value (src) | |
333 | register rtx src; | |
334 | { | |
335 | switch (GET_CODE (src)) | |
336 | { | |
337 | case SYMBOL_REF: | |
338 | case LABEL_REF: | |
339 | return src; | |
340 | ||
341 | case REG: | |
2a2c8203 JC |
342 | /* At the start of a function argument registers have known base |
343 | values which may be lost later. Returning an ADDRESS | |
344 | expression here allows optimization based on argument values | |
345 | even when the argument registers are used for other purposes. */ | |
346 | if (REGNO (src) < FIRST_PSEUDO_REGISTER && copying_arguments) | |
ec907dd8 | 347 | return new_reg_base_value[REGNO (src)]; |
73774bc7 | 348 | |
eaf407a5 JL |
349 | /* If a pseudo has a known base value, return it. Do not do this |
350 | for hard regs since it can result in a circular dependency | |
351 | chain for registers which have values at function entry. | |
352 | ||
353 | The test above is not sufficient because the scheduler may move | |
354 | a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */ | |
355 | if (REGNO (src) >= FIRST_PSEUDO_REGISTER | |
e51712db | 356 | && (unsigned) REGNO (src) < reg_base_value_size |
eaf407a5 | 357 | && reg_base_value[REGNO (src)]) |
73774bc7 JL |
358 | return reg_base_value[REGNO (src)]; |
359 | ||
9ae8ffe7 JL |
360 | return src; |
361 | ||
362 | case MEM: | |
363 | /* Check for an argument passed in memory. Only record in the | |
364 | copying-arguments block; it is too hard to track changes | |
365 | otherwise. */ | |
366 | if (copying_arguments | |
367 | && (XEXP (src, 0) == arg_pointer_rtx | |
368 | || (GET_CODE (XEXP (src, 0)) == PLUS | |
369 | && XEXP (XEXP (src, 0), 0) == arg_pointer_rtx))) | |
38a448ca | 370 | return gen_rtx_ADDRESS (VOIDmode, src); |
9ae8ffe7 JL |
371 | return 0; |
372 | ||
373 | case CONST: | |
374 | src = XEXP (src, 0); | |
375 | if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS) | |
376 | break; | |
377 | /* fall through */ | |
2a2c8203 | 378 | |
9ae8ffe7 JL |
379 | case PLUS: |
380 | case MINUS: | |
2a2c8203 | 381 | { |
ec907dd8 JL |
382 | rtx temp, src_0 = XEXP (src, 0), src_1 = XEXP (src, 1); |
383 | ||
384 | /* If either operand is a REG, then see if we already have | |
385 | a known value for it. */ | |
386 | if (GET_CODE (src_0) == REG) | |
387 | { | |
388 | temp = find_base_value (src_0); | |
389 | if (temp) | |
390 | src_0 = temp; | |
391 | } | |
392 | ||
393 | if (GET_CODE (src_1) == REG) | |
394 | { | |
395 | temp = find_base_value (src_1); | |
396 | if (temp) | |
397 | src_1 = temp; | |
398 | } | |
2a2c8203 JC |
399 | |
400 | /* Guess which operand is the base address. | |
401 | ||
ec907dd8 JL |
402 | If either operand is a symbol, then it is the base. If |
403 | either operand is a CONST_INT, then the other is the base. */ | |
2a2c8203 JC |
404 | |
405 | if (GET_CODE (src_1) == CONST_INT | |
406 | || GET_CODE (src_0) == SYMBOL_REF | |
407 | || GET_CODE (src_0) == LABEL_REF | |
408 | || GET_CODE (src_0) == CONST) | |
409 | return find_base_value (src_0); | |
410 | ||
ec907dd8 JL |
411 | if (GET_CODE (src_0) == CONST_INT |
412 | || GET_CODE (src_1) == SYMBOL_REF | |
413 | || GET_CODE (src_1) == LABEL_REF | |
414 | || GET_CODE (src_1) == CONST) | |
415 | return find_base_value (src_1); | |
416 | ||
417 | /* This might not be necessary anymore. | |
418 | ||
419 | If either operand is a REG that is a known pointer, then it | |
420 | is the base. */ | |
2a2c8203 JC |
421 | if (GET_CODE (src_0) == REG && REGNO_POINTER_FLAG (REGNO (src_0))) |
422 | return find_base_value (src_0); | |
423 | ||
424 | if (GET_CODE (src_1) == REG && REGNO_POINTER_FLAG (REGNO (src_1))) | |
425 | return find_base_value (src_1); | |
426 | ||
9ae8ffe7 | 427 | return 0; |
2a2c8203 JC |
428 | } |
429 | ||
430 | case LO_SUM: | |
431 | /* The standard form is (lo_sum reg sym) so look only at the | |
432 | second operand. */ | |
433 | return find_base_value (XEXP (src, 1)); | |
9ae8ffe7 JL |
434 | |
435 | case AND: | |
436 | /* If the second operand is constant set the base | |
437 | address to the first operand. */ | |
2a2c8203 JC |
438 | if (GET_CODE (XEXP (src, 1)) == CONST_INT && INTVAL (XEXP (src, 1)) != 0) |
439 | return find_base_value (XEXP (src, 0)); | |
9ae8ffe7 JL |
440 | return 0; |
441 | ||
de12be17 JC |
442 | case ZERO_EXTEND: |
443 | case SIGN_EXTEND: /* used for NT/Alpha pointers */ | |
9ae8ffe7 | 444 | case HIGH: |
2a2c8203 | 445 | return find_base_value (XEXP (src, 0)); |
1d300e19 KG |
446 | |
447 | default: | |
448 | break; | |
9ae8ffe7 JL |
449 | } |
450 | ||
451 | return 0; | |
452 | } | |
453 | ||
454 | /* Called from init_alias_analysis indirectly through note_stores. */ | |
455 | ||
456 | /* while scanning insns to find base values, reg_seen[N] is nonzero if | |
457 | register N has been set in this function. */ | |
458 | static char *reg_seen; | |
459 | ||
13309a5f JC |
460 | /* Addresses which are known not to alias anything else are identified |
461 | by a unique integer. */ | |
ec907dd8 JL |
462 | static int unique_id; |
463 | ||
2a2c8203 JC |
464 | static void |
465 | record_set (dest, set) | |
9ae8ffe7 JL |
466 | rtx dest, set; |
467 | { | |
468 | register int regno; | |
469 | rtx src; | |
470 | ||
471 | if (GET_CODE (dest) != REG) | |
472 | return; | |
473 | ||
474 | regno = REGNO (dest); | |
475 | ||
476 | if (set) | |
477 | { | |
478 | /* A CLOBBER wipes out any old value but does not prevent a previously | |
479 | unset register from acquiring a base address (i.e. reg_seen is not | |
480 | set). */ | |
481 | if (GET_CODE (set) == CLOBBER) | |
482 | { | |
ec907dd8 | 483 | new_reg_base_value[regno] = 0; |
9ae8ffe7 JL |
484 | return; |
485 | } | |
486 | src = SET_SRC (set); | |
487 | } | |
488 | else | |
489 | { | |
9ae8ffe7 JL |
490 | if (reg_seen[regno]) |
491 | { | |
ec907dd8 | 492 | new_reg_base_value[regno] = 0; |
9ae8ffe7 JL |
493 | return; |
494 | } | |
495 | reg_seen[regno] = 1; | |
38a448ca RH |
496 | new_reg_base_value[regno] = gen_rtx_ADDRESS (Pmode, |
497 | GEN_INT (unique_id++)); | |
9ae8ffe7 JL |
498 | return; |
499 | } | |
500 | ||
501 | /* This is not the first set. If the new value is not related to the | |
502 | old value, forget the base value. Note that the following code is | |
503 | not detected: | |
504 | extern int x, y; int *p = &x; p += (&y-&x); | |
505 | ANSI C does not allow computing the difference of addresses | |
506 | of distinct top level objects. */ | |
ec907dd8 | 507 | if (new_reg_base_value[regno]) |
9ae8ffe7 JL |
508 | switch (GET_CODE (src)) |
509 | { | |
2a2c8203 | 510 | case LO_SUM: |
9ae8ffe7 JL |
511 | case PLUS: |
512 | case MINUS: | |
513 | if (XEXP (src, 0) != dest && XEXP (src, 1) != dest) | |
ec907dd8 | 514 | new_reg_base_value[regno] = 0; |
9ae8ffe7 JL |
515 | break; |
516 | case AND: | |
517 | if (XEXP (src, 0) != dest || GET_CODE (XEXP (src, 1)) != CONST_INT) | |
ec907dd8 | 518 | new_reg_base_value[regno] = 0; |
9ae8ffe7 | 519 | break; |
9ae8ffe7 | 520 | default: |
ec907dd8 | 521 | new_reg_base_value[regno] = 0; |
9ae8ffe7 JL |
522 | break; |
523 | } | |
524 | /* If this is the first set of a register, record the value. */ | |
525 | else if ((regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno]) | |
ec907dd8 JL |
526 | && ! reg_seen[regno] && new_reg_base_value[regno] == 0) |
527 | new_reg_base_value[regno] = find_base_value (src); | |
9ae8ffe7 JL |
528 | |
529 | reg_seen[regno] = 1; | |
530 | } | |
531 | ||
532 | /* Called from loop optimization when a new pseudo-register is created. */ | |
533 | void | |
de12be17 | 534 | record_base_value (regno, val, invariant) |
9ae8ffe7 JL |
535 | int regno; |
536 | rtx val; | |
de12be17 | 537 | int invariant; |
9ae8ffe7 | 538 | { |
e51712db | 539 | if ((unsigned) regno >= reg_base_value_size) |
9ae8ffe7 | 540 | return; |
de12be17 JC |
541 | |
542 | /* If INVARIANT is true then this value also describes an invariant | |
543 | relationship which can be used to deduce that two registers with | |
544 | unknown values are different. */ | |
545 | if (invariant && alias_invariant) | |
546 | alias_invariant[regno] = val; | |
547 | ||
9ae8ffe7 JL |
548 | if (GET_CODE (val) == REG) |
549 | { | |
e51712db | 550 | if ((unsigned) REGNO (val) < reg_base_value_size) |
de12be17 JC |
551 | { |
552 | reg_base_value[regno] = reg_base_value[REGNO (val)]; | |
553 | } | |
9ae8ffe7 JL |
554 | return; |
555 | } | |
556 | reg_base_value[regno] = find_base_value (val); | |
557 | } | |
558 | ||
559 | static rtx | |
560 | canon_rtx (x) | |
561 | rtx x; | |
562 | { | |
563 | /* Recursively look for equivalences. */ | |
564 | if (GET_CODE (x) == REG && REGNO (x) >= FIRST_PSEUDO_REGISTER | |
565 | && REGNO (x) < reg_known_value_size) | |
566 | return reg_known_value[REGNO (x)] == x | |
567 | ? x : canon_rtx (reg_known_value[REGNO (x)]); | |
568 | else if (GET_CODE (x) == PLUS) | |
569 | { | |
570 | rtx x0 = canon_rtx (XEXP (x, 0)); | |
571 | rtx x1 = canon_rtx (XEXP (x, 1)); | |
572 | ||
573 | if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1)) | |
574 | { | |
575 | /* We can tolerate LO_SUMs being offset here; these | |
576 | rtl are used for nothing other than comparisons. */ | |
577 | if (GET_CODE (x0) == CONST_INT) | |
578 | return plus_constant_for_output (x1, INTVAL (x0)); | |
579 | else if (GET_CODE (x1) == CONST_INT) | |
580 | return plus_constant_for_output (x0, INTVAL (x1)); | |
38a448ca | 581 | return gen_rtx_PLUS (GET_MODE (x), x0, x1); |
9ae8ffe7 JL |
582 | } |
583 | } | |
584 | /* This gives us much better alias analysis when called from | |
585 | the loop optimizer. Note we want to leave the original | |
586 | MEM alone, but need to return the canonicalized MEM with | |
587 | all the flags with their original values. */ | |
588 | else if (GET_CODE (x) == MEM) | |
589 | { | |
590 | rtx addr = canon_rtx (XEXP (x, 0)); | |
591 | if (addr != XEXP (x, 0)) | |
592 | { | |
38a448ca | 593 | rtx new = gen_rtx_MEM (GET_MODE (x), addr); |
9ae8ffe7 | 594 | RTX_UNCHANGING_P (new) = RTX_UNCHANGING_P (x); |
c6df88cb | 595 | MEM_COPY_ATTRIBUTES (new, x); |
41472af8 | 596 | MEM_ALIAS_SET (new) = MEM_ALIAS_SET (x); |
9ae8ffe7 JL |
597 | x = new; |
598 | } | |
599 | } | |
600 | return x; | |
601 | } | |
602 | ||
603 | /* Return 1 if X and Y are identical-looking rtx's. | |
604 | ||
605 | We use the data in reg_known_value above to see if two registers with | |
606 | different numbers are, in fact, equivalent. */ | |
607 | ||
608 | static int | |
609 | rtx_equal_for_memref_p (x, y) | |
610 | rtx x, y; | |
611 | { | |
612 | register int i; | |
613 | register int j; | |
614 | register enum rtx_code code; | |
615 | register char *fmt; | |
616 | ||
617 | if (x == 0 && y == 0) | |
618 | return 1; | |
619 | if (x == 0 || y == 0) | |
620 | return 0; | |
621 | x = canon_rtx (x); | |
622 | y = canon_rtx (y); | |
623 | ||
624 | if (x == y) | |
625 | return 1; | |
626 | ||
627 | code = GET_CODE (x); | |
628 | /* Rtx's of different codes cannot be equal. */ | |
629 | if (code != GET_CODE (y)) | |
630 | return 0; | |
631 | ||
632 | /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. | |
633 | (REG:SI x) and (REG:HI x) are NOT equivalent. */ | |
634 | ||
635 | if (GET_MODE (x) != GET_MODE (y)) | |
636 | return 0; | |
637 | ||
638 | /* REG, LABEL_REF, and SYMBOL_REF can be compared nonrecursively. */ | |
639 | ||
640 | if (code == REG) | |
641 | return REGNO (x) == REGNO (y); | |
642 | if (code == LABEL_REF) | |
643 | return XEXP (x, 0) == XEXP (y, 0); | |
644 | if (code == SYMBOL_REF) | |
645 | return XSTR (x, 0) == XSTR (y, 0); | |
de12be17 JC |
646 | if (code == CONST_INT) |
647 | return INTVAL (x) == INTVAL (y); | |
648 | if (code == ADDRESSOF) | |
649 | return REGNO (XEXP (x, 0)) == REGNO (XEXP (y, 0)) && XINT (x, 1) == XINT (y, 1); | |
9ae8ffe7 JL |
650 | |
651 | /* For commutative operations, the RTX match if the operand match in any | |
652 | order. Also handle the simple binary and unary cases without a loop. */ | |
653 | if (code == EQ || code == NE || GET_RTX_CLASS (code) == 'c') | |
654 | return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)) | |
655 | && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1))) | |
656 | || (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1)) | |
657 | && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0)))); | |
658 | else if (GET_RTX_CLASS (code) == '<' || GET_RTX_CLASS (code) == '2') | |
659 | return (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)) | |
660 | && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1))); | |
661 | else if (GET_RTX_CLASS (code) == '1') | |
662 | return rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)); | |
663 | ||
664 | /* Compare the elements. If any pair of corresponding elements | |
de12be17 JC |
665 | fail to match, return 0 for the whole things. |
666 | ||
667 | Limit cases to types which actually appear in addresses. */ | |
9ae8ffe7 JL |
668 | |
669 | fmt = GET_RTX_FORMAT (code); | |
670 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
671 | { | |
672 | switch (fmt[i]) | |
673 | { | |
9ae8ffe7 JL |
674 | case 'i': |
675 | if (XINT (x, i) != XINT (y, i)) | |
676 | return 0; | |
677 | break; | |
678 | ||
9ae8ffe7 JL |
679 | case 'E': |
680 | /* Two vectors must have the same length. */ | |
681 | if (XVECLEN (x, i) != XVECLEN (y, i)) | |
682 | return 0; | |
683 | ||
684 | /* And the corresponding elements must match. */ | |
685 | for (j = 0; j < XVECLEN (x, i); j++) | |
686 | if (rtx_equal_for_memref_p (XVECEXP (x, i, j), XVECEXP (y, i, j)) == 0) | |
687 | return 0; | |
688 | break; | |
689 | ||
690 | case 'e': | |
691 | if (rtx_equal_for_memref_p (XEXP (x, i), XEXP (y, i)) == 0) | |
692 | return 0; | |
693 | break; | |
694 | ||
aee21ba9 JL |
695 | /* This can happen for an asm which clobbers memory. */ |
696 | case '0': | |
697 | break; | |
698 | ||
9ae8ffe7 JL |
699 | /* It is believed that rtx's at this level will never |
700 | contain anything but integers and other rtx's, | |
701 | except for within LABEL_REFs and SYMBOL_REFs. */ | |
702 | default: | |
703 | abort (); | |
704 | } | |
705 | } | |
706 | return 1; | |
707 | } | |
708 | ||
709 | /* Given an rtx X, find a SYMBOL_REF or LABEL_REF within | |
710 | X and return it, or return 0 if none found. */ | |
711 | ||
712 | static rtx | |
713 | find_symbolic_term (x) | |
714 | rtx x; | |
715 | { | |
716 | register int i; | |
717 | register enum rtx_code code; | |
718 | register char *fmt; | |
719 | ||
720 | code = GET_CODE (x); | |
721 | if (code == SYMBOL_REF || code == LABEL_REF) | |
722 | return x; | |
723 | if (GET_RTX_CLASS (code) == 'o') | |
724 | return 0; | |
725 | ||
726 | fmt = GET_RTX_FORMAT (code); | |
727 | for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
728 | { | |
729 | rtx t; | |
730 | ||
731 | if (fmt[i] == 'e') | |
732 | { | |
733 | t = find_symbolic_term (XEXP (x, i)); | |
734 | if (t != 0) | |
735 | return t; | |
736 | } | |
737 | else if (fmt[i] == 'E') | |
738 | break; | |
739 | } | |
740 | return 0; | |
741 | } | |
742 | ||
743 | static rtx | |
744 | find_base_term (x) | |
745 | register rtx x; | |
746 | { | |
747 | switch (GET_CODE (x)) | |
748 | { | |
749 | case REG: | |
750 | return REG_BASE_VALUE (x); | |
751 | ||
de12be17 JC |
752 | case ZERO_EXTEND: |
753 | case SIGN_EXTEND: /* Used for Alpha/NT pointers */ | |
9ae8ffe7 | 754 | case HIGH: |
6d849a2a JL |
755 | case PRE_INC: |
756 | case PRE_DEC: | |
757 | case POST_INC: | |
758 | case POST_DEC: | |
759 | return find_base_term (XEXP (x, 0)); | |
760 | ||
9ae8ffe7 JL |
761 | case CONST: |
762 | x = XEXP (x, 0); | |
763 | if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS) | |
764 | return 0; | |
765 | /* fall through */ | |
766 | case LO_SUM: | |
767 | case PLUS: | |
768 | case MINUS: | |
769 | { | |
770 | rtx tmp = find_base_term (XEXP (x, 0)); | |
771 | if (tmp) | |
772 | return tmp; | |
773 | return find_base_term (XEXP (x, 1)); | |
774 | } | |
775 | ||
776 | case AND: | |
777 | if (GET_CODE (XEXP (x, 0)) == REG && GET_CODE (XEXP (x, 1)) == CONST_INT) | |
778 | return REG_BASE_VALUE (XEXP (x, 0)); | |
779 | return 0; | |
780 | ||
781 | case SYMBOL_REF: | |
782 | case LABEL_REF: | |
783 | return x; | |
784 | ||
785 | default: | |
786 | return 0; | |
787 | } | |
788 | } | |
789 | ||
790 | /* Return 0 if the addresses X and Y are known to point to different | |
791 | objects, 1 if they might be pointers to the same object. */ | |
792 | ||
793 | static int | |
56ee9281 | 794 | base_alias_check (x, y, x_mode, y_mode) |
9ae8ffe7 | 795 | rtx x, y; |
56ee9281 | 796 | enum machine_mode x_mode, y_mode; |
9ae8ffe7 JL |
797 | { |
798 | rtx x_base = find_base_term (x); | |
799 | rtx y_base = find_base_term (y); | |
800 | ||
1c72c7f6 JC |
801 | /* If the address itself has no known base see if a known equivalent |
802 | value has one. If either address still has no known base, nothing | |
803 | is known about aliasing. */ | |
804 | if (x_base == 0) | |
805 | { | |
806 | rtx x_c; | |
807 | if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x) | |
808 | return 1; | |
809 | x_base = find_base_term (x_c); | |
810 | if (x_base == 0) | |
811 | return 1; | |
812 | } | |
9ae8ffe7 | 813 | |
1c72c7f6 JC |
814 | if (y_base == 0) |
815 | { | |
816 | rtx y_c; | |
817 | if (! flag_expensive_optimizations || (y_c = canon_rtx (y)) == y) | |
818 | return 1; | |
819 | y_base = find_base_term (y_c); | |
820 | if (y_base == 0) | |
821 | return 1; | |
822 | } | |
823 | ||
824 | /* If the base addresses are equal nothing is known about aliasing. */ | |
825 | if (rtx_equal_p (x_base, y_base)) | |
9ae8ffe7 JL |
826 | return 1; |
827 | ||
56ee9281 RH |
828 | /* The base addresses of the read and write are different expressions. |
829 | If they are both symbols and they are not accessed via AND, there is | |
830 | no conflict. We can bring knowledge of object alignment into play | |
831 | here. For example, on alpha, "char a, b;" can alias one another, | |
832 | though "char a; long b;" cannot. */ | |
9ae8ffe7 | 833 | if (GET_CODE (x_base) != ADDRESS && GET_CODE (y_base) != ADDRESS) |
c02f035f | 834 | { |
56ee9281 RH |
835 | if (GET_CODE (x) == AND && GET_CODE (y) == AND) |
836 | return 1; | |
837 | if (GET_CODE (x) == AND | |
838 | && (GET_CODE (XEXP (x, 1)) != CONST_INT | |
839 | || GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1)))) | |
840 | return 1; | |
841 | if (GET_CODE (y) == AND | |
842 | && (GET_CODE (XEXP (y, 1)) != CONST_INT | |
843 | || GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1)))) | |
844 | return 1; | |
b2972551 JL |
845 | /* Differing symbols never alias. */ |
846 | return 0; | |
c02f035f | 847 | } |
9ae8ffe7 JL |
848 | |
849 | /* If one address is a stack reference there can be no alias: | |
850 | stack references using different base registers do not alias, | |
851 | a stack reference can not alias a parameter, and a stack reference | |
852 | can not alias a global. */ | |
853 | if ((GET_CODE (x_base) == ADDRESS && GET_MODE (x_base) == Pmode) | |
854 | || (GET_CODE (y_base) == ADDRESS && GET_MODE (y_base) == Pmode)) | |
855 | return 0; | |
856 | ||
857 | if (! flag_argument_noalias) | |
858 | return 1; | |
859 | ||
860 | if (flag_argument_noalias > 1) | |
861 | return 0; | |
862 | ||
863 | /* Weak noalias assertion (arguments are distinct, but may match globals). */ | |
864 | return ! (GET_MODE (x_base) == VOIDmode && GET_MODE (y_base) == VOIDmode); | |
865 | } | |
866 | ||
39cec1ac MH |
867 | /* Return the address of the (N_REFS + 1)th memory reference to ADDR |
868 | where SIZE is the size in bytes of the memory reference. If ADDR | |
869 | is not modified by the memory reference then ADDR is returned. */ | |
870 | ||
871 | rtx | |
872 | addr_side_effect_eval (addr, size, n_refs) | |
873 | rtx addr; | |
874 | int size; | |
875 | int n_refs; | |
876 | { | |
877 | int offset = 0; | |
878 | ||
879 | switch (GET_CODE (addr)) | |
880 | { | |
881 | case PRE_INC: | |
882 | offset = (n_refs + 1) * size; | |
883 | break; | |
884 | case PRE_DEC: | |
885 | offset = -(n_refs + 1) * size; | |
886 | break; | |
887 | case POST_INC: | |
888 | offset = n_refs * size; | |
889 | break; | |
890 | case POST_DEC: | |
891 | offset = -n_refs * size; | |
892 | break; | |
893 | ||
894 | default: | |
895 | return addr; | |
896 | } | |
897 | ||
898 | if (offset) | |
899 | addr = gen_rtx_PLUS (GET_MODE (addr), XEXP (addr, 0), GEN_INT (offset)); | |
900 | else | |
901 | addr = XEXP (addr, 0); | |
902 | ||
903 | return addr; | |
904 | } | |
905 | ||
9ae8ffe7 JL |
906 | /* Return nonzero if X and Y (memory addresses) could reference the |
907 | same location in memory. C is an offset accumulator. When | |
908 | C is nonzero, we are testing aliases between X and Y + C. | |
909 | XSIZE is the size in bytes of the X reference, | |
910 | similarly YSIZE is the size in bytes for Y. | |
911 | ||
912 | If XSIZE or YSIZE is zero, we do not know the amount of memory being | |
913 | referenced (the reference was BLKmode), so make the most pessimistic | |
914 | assumptions. | |
915 | ||
c02f035f RH |
916 | If XSIZE or YSIZE is negative, we may access memory outside the object |
917 | being referenced as a side effect. This can happen when using AND to | |
918 | align memory references, as is done on the Alpha. | |
919 | ||
9ae8ffe7 | 920 | Nice to notice that varying addresses cannot conflict with fp if no |
0211b6ab | 921 | local variables had their addresses taken, but that's too hard now. */ |
9ae8ffe7 JL |
922 | |
923 | ||
924 | static int | |
925 | memrefs_conflict_p (xsize, x, ysize, y, c) | |
926 | register rtx x, y; | |
927 | int xsize, ysize; | |
928 | HOST_WIDE_INT c; | |
929 | { | |
930 | if (GET_CODE (x) == HIGH) | |
931 | x = XEXP (x, 0); | |
932 | else if (GET_CODE (x) == LO_SUM) | |
933 | x = XEXP (x, 1); | |
934 | else | |
39cec1ac | 935 | x = canon_rtx (addr_side_effect_eval (x, xsize, 0)); |
9ae8ffe7 JL |
936 | if (GET_CODE (y) == HIGH) |
937 | y = XEXP (y, 0); | |
938 | else if (GET_CODE (y) == LO_SUM) | |
939 | y = XEXP (y, 1); | |
940 | else | |
39cec1ac | 941 | y = canon_rtx (addr_side_effect_eval (y, ysize, 0)); |
9ae8ffe7 JL |
942 | |
943 | if (rtx_equal_for_memref_p (x, y)) | |
944 | { | |
c02f035f | 945 | if (xsize <= 0 || ysize <= 0) |
9ae8ffe7 JL |
946 | return 1; |
947 | if (c >= 0 && xsize > c) | |
948 | return 1; | |
949 | if (c < 0 && ysize+c > 0) | |
950 | return 1; | |
951 | return 0; | |
952 | } | |
953 | ||
6e73e666 JC |
954 | /* This code used to check for conflicts involving stack references and |
955 | globals but the base address alias code now handles these cases. */ | |
9ae8ffe7 JL |
956 | |
957 | if (GET_CODE (x) == PLUS) | |
958 | { | |
959 | /* The fact that X is canonicalized means that this | |
960 | PLUS rtx is canonicalized. */ | |
961 | rtx x0 = XEXP (x, 0); | |
962 | rtx x1 = XEXP (x, 1); | |
963 | ||
964 | if (GET_CODE (y) == PLUS) | |
965 | { | |
966 | /* The fact that Y is canonicalized means that this | |
967 | PLUS rtx is canonicalized. */ | |
968 | rtx y0 = XEXP (y, 0); | |
969 | rtx y1 = XEXP (y, 1); | |
970 | ||
971 | if (rtx_equal_for_memref_p (x1, y1)) | |
972 | return memrefs_conflict_p (xsize, x0, ysize, y0, c); | |
973 | if (rtx_equal_for_memref_p (x0, y0)) | |
974 | return memrefs_conflict_p (xsize, x1, ysize, y1, c); | |
975 | if (GET_CODE (x1) == CONST_INT) | |
63be02db JM |
976 | { |
977 | if (GET_CODE (y1) == CONST_INT) | |
978 | return memrefs_conflict_p (xsize, x0, ysize, y0, | |
979 | c - INTVAL (x1) + INTVAL (y1)); | |
980 | else | |
981 | return memrefs_conflict_p (xsize, x0, ysize, y, | |
982 | c - INTVAL (x1)); | |
983 | } | |
9ae8ffe7 JL |
984 | else if (GET_CODE (y1) == CONST_INT) |
985 | return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1)); | |
986 | ||
6e73e666 | 987 | return 1; |
9ae8ffe7 JL |
988 | } |
989 | else if (GET_CODE (x1) == CONST_INT) | |
990 | return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1)); | |
991 | } | |
992 | else if (GET_CODE (y) == PLUS) | |
993 | { | |
994 | /* The fact that Y is canonicalized means that this | |
995 | PLUS rtx is canonicalized. */ | |
996 | rtx y0 = XEXP (y, 0); | |
997 | rtx y1 = XEXP (y, 1); | |
998 | ||
999 | if (GET_CODE (y1) == CONST_INT) | |
1000 | return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1)); | |
1001 | else | |
1002 | return 1; | |
1003 | } | |
1004 | ||
1005 | if (GET_CODE (x) == GET_CODE (y)) | |
1006 | switch (GET_CODE (x)) | |
1007 | { | |
1008 | case MULT: | |
1009 | { | |
1010 | /* Handle cases where we expect the second operands to be the | |
1011 | same, and check only whether the first operand would conflict | |
1012 | or not. */ | |
1013 | rtx x0, y0; | |
1014 | rtx x1 = canon_rtx (XEXP (x, 1)); | |
1015 | rtx y1 = canon_rtx (XEXP (y, 1)); | |
1016 | if (! rtx_equal_for_memref_p (x1, y1)) | |
1017 | return 1; | |
1018 | x0 = canon_rtx (XEXP (x, 0)); | |
1019 | y0 = canon_rtx (XEXP (y, 0)); | |
1020 | if (rtx_equal_for_memref_p (x0, y0)) | |
1021 | return (xsize == 0 || ysize == 0 | |
1022 | || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0)); | |
1023 | ||
1024 | /* Can't properly adjust our sizes. */ | |
1025 | if (GET_CODE (x1) != CONST_INT) | |
1026 | return 1; | |
1027 | xsize /= INTVAL (x1); | |
1028 | ysize /= INTVAL (x1); | |
1029 | c /= INTVAL (x1); | |
1030 | return memrefs_conflict_p (xsize, x0, ysize, y0, c); | |
1031 | } | |
1d300e19 | 1032 | |
de12be17 JC |
1033 | case REG: |
1034 | /* Are these registers known not to be equal? */ | |
1035 | if (alias_invariant) | |
1036 | { | |
e51712db | 1037 | unsigned int r_x = REGNO (x), r_y = REGNO (y); |
de12be17 JC |
1038 | rtx i_x, i_y; /* invariant relationships of X and Y */ |
1039 | ||
1040 | i_x = r_x >= reg_base_value_size ? 0 : alias_invariant[r_x]; | |
1041 | i_y = r_y >= reg_base_value_size ? 0 : alias_invariant[r_y]; | |
1042 | ||
1043 | if (i_x == 0 && i_y == 0) | |
1044 | break; | |
1045 | ||
1046 | if (! memrefs_conflict_p (xsize, i_x ? i_x : x, | |
1047 | ysize, i_y ? i_y : y, c)) | |
1048 | return 0; | |
1049 | } | |
1050 | break; | |
1051 | ||
1d300e19 KG |
1052 | default: |
1053 | break; | |
9ae8ffe7 JL |
1054 | } |
1055 | ||
1056 | /* Treat an access through an AND (e.g. a subword access on an Alpha) | |
56ee9281 RH |
1057 | as an access with indeterminate size. Assume that references |
1058 | besides AND are aligned, so if the size of the other reference is | |
1059 | at least as large as the alignment, assume no other overlap. */ | |
9ae8ffe7 | 1060 | if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT) |
56ee9281 | 1061 | { |
02e3377d | 1062 | if (GET_CODE (y) == AND || ysize < -INTVAL (XEXP (x, 1))) |
56ee9281 RH |
1063 | xsize = -1; |
1064 | return memrefs_conflict_p (xsize, XEXP (x, 0), ysize, y, c); | |
1065 | } | |
9ae8ffe7 | 1066 | if (GET_CODE (y) == AND && GET_CODE (XEXP (y, 1)) == CONST_INT) |
c02f035f | 1067 | { |
56ee9281 | 1068 | /* ??? If we are indexing far enough into the array/structure, we |
c02f035f RH |
1069 | may yet be able to determine that we can not overlap. But we |
1070 | also need to that we are far enough from the end not to overlap | |
56ee9281 | 1071 | a following reference, so we do nothing with that for now. */ |
02e3377d | 1072 | if (GET_CODE (x) == AND || xsize < -INTVAL (XEXP (y, 1))) |
56ee9281 RH |
1073 | ysize = -1; |
1074 | return memrefs_conflict_p (xsize, x, ysize, XEXP (y, 0), c); | |
c02f035f | 1075 | } |
9ae8ffe7 JL |
1076 | |
1077 | if (CONSTANT_P (x)) | |
1078 | { | |
1079 | if (GET_CODE (x) == CONST_INT && GET_CODE (y) == CONST_INT) | |
1080 | { | |
1081 | c += (INTVAL (y) - INTVAL (x)); | |
c02f035f | 1082 | return (xsize <= 0 || ysize <= 0 |
9ae8ffe7 JL |
1083 | || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0)); |
1084 | } | |
1085 | ||
1086 | if (GET_CODE (x) == CONST) | |
1087 | { | |
1088 | if (GET_CODE (y) == CONST) | |
1089 | return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), | |
1090 | ysize, canon_rtx (XEXP (y, 0)), c); | |
1091 | else | |
1092 | return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), | |
1093 | ysize, y, c); | |
1094 | } | |
1095 | if (GET_CODE (y) == CONST) | |
1096 | return memrefs_conflict_p (xsize, x, ysize, | |
1097 | canon_rtx (XEXP (y, 0)), c); | |
1098 | ||
1099 | if (CONSTANT_P (y)) | |
c02f035f RH |
1100 | return (xsize < 0 || ysize < 0 |
1101 | || (rtx_equal_for_memref_p (x, y) | |
1102 | && (xsize == 0 || ysize == 0 | |
1103 | || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0)))); | |
9ae8ffe7 JL |
1104 | |
1105 | return 1; | |
1106 | } | |
1107 | return 1; | |
1108 | } | |
1109 | ||
1110 | /* Functions to compute memory dependencies. | |
1111 | ||
1112 | Since we process the insns in execution order, we can build tables | |
1113 | to keep track of what registers are fixed (and not aliased), what registers | |
1114 | are varying in known ways, and what registers are varying in unknown | |
1115 | ways. | |
1116 | ||
1117 | If both memory references are volatile, then there must always be a | |
1118 | dependence between the two references, since their order can not be | |
1119 | changed. A volatile and non-volatile reference can be interchanged | |
1120 | though. | |
1121 | ||
fa8b6024 | 1122 | A MEM_IN_STRUCT reference at a non-QImode non-AND varying address can never |
9ae8ffe7 JL |
1123 | conflict with a non-MEM_IN_STRUCT reference at a fixed address. We must |
1124 | allow QImode aliasing because the ANSI C standard allows character | |
1125 | pointers to alias anything. We are assuming that characters are | |
fa8b6024 JW |
1126 | always QImode here. We also must allow AND addresses, because they may |
1127 | generate accesses outside the object being referenced. This is used to | |
1128 | generate aligned addresses from unaligned addresses, for instance, the | |
1129 | alpha storeqi_unaligned pattern. */ | |
9ae8ffe7 JL |
1130 | |
1131 | /* Read dependence: X is read after read in MEM takes place. There can | |
1132 | only be a dependence here if both reads are volatile. */ | |
1133 | ||
1134 | int | |
1135 | read_dependence (mem, x) | |
1136 | rtx mem; | |
1137 | rtx x; | |
1138 | { | |
1139 | return MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem); | |
1140 | } | |
1141 | ||
c6df88cb MM |
1142 | /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and |
1143 | MEM2 is a reference to a structure at a varying address, or returns | |
1144 | MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL | |
1145 | value is returned MEM1 and MEM2 can never alias. VARIES_P is used | |
1146 | to decide whether or not an address may vary; it should return | |
1147 | nozero whenever variation is possible. */ | |
1148 | ||
1149 | rtx | |
1150 | fixed_scalar_and_varying_struct_p (mem1, mem2, varies_p) | |
1151 | rtx mem1; | |
1152 | rtx mem2; | |
1153 | int (*varies_p) PROTO((rtx)); | |
1154 | { | |
1155 | rtx mem1_addr = XEXP (mem1, 0); | |
1156 | rtx mem2_addr = XEXP (mem2, 0); | |
1157 | ||
1158 | if (MEM_SCALAR_P (mem1) && MEM_IN_STRUCT_P (mem2) | |
1159 | && !varies_p (mem1_addr) && varies_p (mem2_addr)) | |
1160 | /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a | |
1161 | varying address. */ | |
1162 | return mem1; | |
1163 | ||
1164 | if (MEM_IN_STRUCT_P (mem1) && MEM_SCALAR_P (mem2) | |
1165 | && varies_p (mem1_addr) && !varies_p (mem2_addr)) | |
1166 | /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a | |
1167 | varying address. */ | |
1168 | return mem2; | |
1169 | ||
1170 | return NULL_RTX; | |
1171 | } | |
1172 | ||
1173 | /* Returns nonzero if something about the mode or address format MEM1 | |
1174 | indicates that it might well alias *anything*. */ | |
1175 | ||
1176 | int | |
1177 | aliases_everything_p (mem) | |
1178 | rtx mem; | |
1179 | { | |
1180 | if (GET_MODE (mem) == QImode) | |
1181 | /* ANSI C says that a `char*' can point to anything. */ | |
1182 | return 1; | |
1183 | ||
1184 | if (GET_CODE (XEXP (mem, 0)) == AND) | |
1185 | /* If the address is an AND, its very hard to know at what it is | |
1186 | actually pointing. */ | |
1187 | return 1; | |
1188 | ||
1189 | return 0; | |
1190 | } | |
1191 | ||
9ae8ffe7 JL |
1192 | /* True dependence: X is read after store in MEM takes place. */ |
1193 | ||
1194 | int | |
1195 | true_dependence (mem, mem_mode, x, varies) | |
1196 | rtx mem; | |
1197 | enum machine_mode mem_mode; | |
1198 | rtx x; | |
960b4ee6 | 1199 | int (*varies) PROTO((rtx)); |
9ae8ffe7 | 1200 | { |
6e73e666 | 1201 | register rtx x_addr, mem_addr; |
9ae8ffe7 JL |
1202 | |
1203 | if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) | |
1204 | return 1; | |
1205 | ||
41472af8 MM |
1206 | if (DIFFERENT_ALIAS_SETS_P (x, mem)) |
1207 | return 0; | |
1208 | ||
9ae8ffe7 JL |
1209 | /* If X is an unchanging read, then it can't possibly conflict with any |
1210 | non-unchanging store. It may conflict with an unchanging write though, | |
1211 | because there may be a single store to this address to initialize it. | |
1212 | Just fall through to the code below to resolve the case where we have | |
1213 | both an unchanging read and an unchanging write. This won't handle all | |
1214 | cases optimally, but the possible performance loss should be | |
1215 | negligible. */ | |
1216 | if (RTX_UNCHANGING_P (x) && ! RTX_UNCHANGING_P (mem)) | |
1217 | return 0; | |
1218 | ||
56ee9281 RH |
1219 | if (mem_mode == VOIDmode) |
1220 | mem_mode = GET_MODE (mem); | |
1221 | ||
1222 | if (! base_alias_check (XEXP (x, 0), XEXP (mem, 0), GET_MODE (x), mem_mode)) | |
1c72c7f6 JC |
1223 | return 0; |
1224 | ||
6e73e666 JC |
1225 | x_addr = canon_rtx (XEXP (x, 0)); |
1226 | mem_addr = canon_rtx (XEXP (mem, 0)); | |
1227 | ||
0211b6ab JW |
1228 | if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr, |
1229 | SIZE_FOR_MODE (x), x_addr, 0)) | |
1230 | return 0; | |
1231 | ||
c6df88cb | 1232 | if (aliases_everything_p (x)) |
0211b6ab JW |
1233 | return 1; |
1234 | ||
c6df88cb MM |
1235 | /* We cannot use aliases_everyting_p to test MEM, since we must look |
1236 | at MEM_MODE, rather than GET_MODE (MEM). */ | |
1237 | if (mem_mode == QImode || GET_CODE (mem_addr) == AND) | |
1238 | return 1; | |
0211b6ab | 1239 | |
c6df88cb MM |
1240 | /* In true_dependence we also allow BLKmode to alias anything. Why |
1241 | don't we do this in anti_dependence and output_dependence? */ | |
1242 | if (mem_mode == BLKmode || GET_MODE (x) == BLKmode) | |
1243 | return 1; | |
0211b6ab | 1244 | |
c6df88cb | 1245 | return !fixed_scalar_and_varying_struct_p (mem, x, varies); |
9ae8ffe7 JL |
1246 | } |
1247 | ||
c6df88cb MM |
1248 | /* Returns non-zero if a write to X might alias a previous read from |
1249 | (or, if WRITEP is non-zero, a write to) MEM. */ | |
9ae8ffe7 JL |
1250 | |
1251 | int | |
c6df88cb | 1252 | write_dependence_p (mem, x, writep) |
9ae8ffe7 JL |
1253 | rtx mem; |
1254 | rtx x; | |
c6df88cb | 1255 | int writep; |
9ae8ffe7 | 1256 | { |
6e73e666 | 1257 | rtx x_addr, mem_addr; |
c6df88cb | 1258 | rtx fixed_scalar; |
6e73e666 | 1259 | |
9ae8ffe7 JL |
1260 | if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) |
1261 | return 1; | |
1262 | ||
9ae8ffe7 JL |
1263 | /* If MEM is an unchanging read, then it can't possibly conflict with |
1264 | the store to X, because there is at most one store to MEM, and it must | |
1265 | have occurred somewhere before MEM. */ | |
c6df88cb | 1266 | if (!writep && RTX_UNCHANGING_P (mem)) |
9ae8ffe7 JL |
1267 | return 0; |
1268 | ||
56ee9281 RH |
1269 | if (! base_alias_check (XEXP (x, 0), XEXP (mem, 0), GET_MODE (x), |
1270 | GET_MODE (mem))) | |
1c72c7f6 JC |
1271 | return 0; |
1272 | ||
1273 | x = canon_rtx (x); | |
1274 | mem = canon_rtx (mem); | |
1275 | ||
41472af8 MM |
1276 | if (DIFFERENT_ALIAS_SETS_P (x, mem)) |
1277 | return 0; | |
1278 | ||
6e73e666 JC |
1279 | x_addr = XEXP (x, 0); |
1280 | mem_addr = XEXP (mem, 0); | |
1281 | ||
c6df88cb MM |
1282 | if (!memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr, |
1283 | SIZE_FOR_MODE (x), x_addr, 0)) | |
1284 | return 0; | |
1285 | ||
1286 | fixed_scalar | |
1287 | = fixed_scalar_and_varying_struct_p (mem, x, rtx_addr_varies_p); | |
1288 | ||
1289 | return (!(fixed_scalar == mem && !aliases_everything_p (x)) | |
1290 | && !(fixed_scalar == x && !aliases_everything_p (mem))); | |
1291 | } | |
1292 | ||
1293 | /* Anti dependence: X is written after read in MEM takes place. */ | |
1294 | ||
1295 | int | |
1296 | anti_dependence (mem, x) | |
1297 | rtx mem; | |
1298 | rtx x; | |
1299 | { | |
1300 | return write_dependence_p (mem, x, /*writep=*/0); | |
9ae8ffe7 JL |
1301 | } |
1302 | ||
1303 | /* Output dependence: X is written after store in MEM takes place. */ | |
1304 | ||
1305 | int | |
1306 | output_dependence (mem, x) | |
1307 | register rtx mem; | |
1308 | register rtx x; | |
1309 | { | |
c6df88cb | 1310 | return write_dependence_p (mem, x, /*writep=*/1); |
9ae8ffe7 JL |
1311 | } |
1312 | ||
6e73e666 JC |
1313 | |
1314 | static HARD_REG_SET argument_registers; | |
1315 | ||
1316 | void | |
1317 | init_alias_once () | |
1318 | { | |
1319 | register int i; | |
1320 | ||
1321 | #ifndef OUTGOING_REGNO | |
1322 | #define OUTGOING_REGNO(N) N | |
1323 | #endif | |
1324 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
1325 | /* Check whether this register can hold an incoming pointer | |
1326 | argument. FUNCTION_ARG_REGNO_P tests outgoing register | |
1327 | numbers, so translate if necessary due to register windows. */ | |
1328 | if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i)) | |
1329 | && HARD_REGNO_MODE_OK (i, Pmode)) | |
1330 | SET_HARD_REG_BIT (argument_registers, i); | |
3932261a | 1331 | |
973838fd | 1332 | alias_sets = splay_tree_new (alias_set_compare, 0, 0); |
6e73e666 JC |
1333 | } |
1334 | ||
9ae8ffe7 JL |
1335 | void |
1336 | init_alias_analysis () | |
1337 | { | |
1338 | int maxreg = max_reg_num (); | |
ea64ef27 | 1339 | int changed, pass; |
9ae8ffe7 | 1340 | register int i; |
e51712db | 1341 | register unsigned int ui; |
9ae8ffe7 | 1342 | register rtx insn; |
9ae8ffe7 JL |
1343 | |
1344 | reg_known_value_size = maxreg; | |
1345 | ||
1346 | reg_known_value | |
1347 | = (rtx *) oballoc ((maxreg - FIRST_PSEUDO_REGISTER) * sizeof (rtx)) | |
1348 | - FIRST_PSEUDO_REGISTER; | |
1349 | reg_known_equiv_p = | |
1350 | oballoc (maxreg - FIRST_PSEUDO_REGISTER) - FIRST_PSEUDO_REGISTER; | |
1351 | bzero ((char *) (reg_known_value + FIRST_PSEUDO_REGISTER), | |
1352 | (maxreg-FIRST_PSEUDO_REGISTER) * sizeof (rtx)); | |
1353 | bzero (reg_known_equiv_p + FIRST_PSEUDO_REGISTER, | |
1354 | (maxreg - FIRST_PSEUDO_REGISTER) * sizeof (char)); | |
1355 | ||
6e73e666 JC |
1356 | /* Overallocate reg_base_value to allow some growth during loop |
1357 | optimization. Loop unrolling can create a large number of | |
1358 | registers. */ | |
1359 | reg_base_value_size = maxreg * 2; | |
1360 | reg_base_value = (rtx *)oballoc (reg_base_value_size * sizeof (rtx)); | |
1361 | new_reg_base_value = (rtx *)alloca (reg_base_value_size * sizeof (rtx)); | |
1362 | reg_seen = (char *)alloca (reg_base_value_size); | |
1363 | bzero ((char *) reg_base_value, reg_base_value_size * sizeof (rtx)); | |
de12be17 JC |
1364 | if (! reload_completed && flag_unroll_loops) |
1365 | { | |
1366 | alias_invariant = (rtx *)xrealloc (alias_invariant, | |
1367 | reg_base_value_size * sizeof (rtx)); | |
1368 | bzero ((char *)alias_invariant, reg_base_value_size * sizeof (rtx)); | |
1369 | } | |
1370 | ||
ec907dd8 JL |
1371 | |
1372 | /* The basic idea is that each pass through this loop will use the | |
1373 | "constant" information from the previous pass to propagate alias | |
1374 | information through another level of assignments. | |
1375 | ||
1376 | This could get expensive if the assignment chains are long. Maybe | |
1377 | we should throttle the number of iterations, possibly based on | |
6e73e666 | 1378 | the optimization level or flag_expensive_optimizations. |
ec907dd8 JL |
1379 | |
1380 | We could propagate more information in the first pass by making use | |
1381 | of REG_N_SETS to determine immediately that the alias information | |
ea64ef27 JL |
1382 | for a pseudo is "constant". |
1383 | ||
1384 | A program with an uninitialized variable can cause an infinite loop | |
1385 | here. Instead of doing a full dataflow analysis to detect such problems | |
1386 | we just cap the number of iterations for the loop. | |
1387 | ||
1388 | The state of the arrays for the set chain in question does not matter | |
1389 | since the program has undefined behavior. */ | |
6e73e666 | 1390 | |
ea64ef27 | 1391 | pass = 0; |
6e73e666 | 1392 | do |
ec907dd8 JL |
1393 | { |
1394 | /* Assume nothing will change this iteration of the loop. */ | |
1395 | changed = 0; | |
1396 | ||
ec907dd8 JL |
1397 | /* We want to assign the same IDs each iteration of this loop, so |
1398 | start counting from zero each iteration of the loop. */ | |
1399 | unique_id = 0; | |
1400 | ||
1401 | /* We're at the start of the funtion each iteration through the | |
1402 | loop, so we're copying arguments. */ | |
1403 | copying_arguments = 1; | |
9ae8ffe7 | 1404 | |
6e73e666 JC |
1405 | /* Wipe the potential alias information clean for this pass. */ |
1406 | bzero ((char *) new_reg_base_value, reg_base_value_size * sizeof (rtx)); | |
8072f69c | 1407 | |
6e73e666 JC |
1408 | /* Wipe the reg_seen array clean. */ |
1409 | bzero ((char *) reg_seen, reg_base_value_size); | |
9ae8ffe7 | 1410 | |
6e73e666 JC |
1411 | /* Mark all hard registers which may contain an address. |
1412 | The stack, frame and argument pointers may contain an address. | |
1413 | An argument register which can hold a Pmode value may contain | |
1414 | an address even if it is not in BASE_REGS. | |
8072f69c | 1415 | |
6e73e666 JC |
1416 | The address expression is VOIDmode for an argument and |
1417 | Pmode for other registers. */ | |
1418 | ||
1419 | for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
1420 | if (TEST_HARD_REG_BIT (argument_registers, i)) | |
38a448ca RH |
1421 | new_reg_base_value[i] = gen_rtx_ADDRESS (VOIDmode, |
1422 | gen_rtx_REG (Pmode, i)); | |
6e73e666 JC |
1423 | |
1424 | new_reg_base_value[STACK_POINTER_REGNUM] | |
38a448ca | 1425 | = gen_rtx_ADDRESS (Pmode, stack_pointer_rtx); |
6e73e666 | 1426 | new_reg_base_value[ARG_POINTER_REGNUM] |
38a448ca | 1427 | = gen_rtx_ADDRESS (Pmode, arg_pointer_rtx); |
6e73e666 | 1428 | new_reg_base_value[FRAME_POINTER_REGNUM] |
38a448ca | 1429 | = gen_rtx_ADDRESS (Pmode, frame_pointer_rtx); |
2a2c8203 | 1430 | #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM |
6e73e666 | 1431 | new_reg_base_value[HARD_FRAME_POINTER_REGNUM] |
38a448ca | 1432 | = gen_rtx_ADDRESS (Pmode, hard_frame_pointer_rtx); |
2a2c8203 | 1433 | #endif |
6e73e666 JC |
1434 | if (struct_value_incoming_rtx |
1435 | && GET_CODE (struct_value_incoming_rtx) == REG) | |
1436 | new_reg_base_value[REGNO (struct_value_incoming_rtx)] | |
38a448ca | 1437 | = gen_rtx_ADDRESS (Pmode, struct_value_incoming_rtx); |
6e73e666 JC |
1438 | |
1439 | if (static_chain_rtx | |
1440 | && GET_CODE (static_chain_rtx) == REG) | |
1441 | new_reg_base_value[REGNO (static_chain_rtx)] | |
38a448ca | 1442 | = gen_rtx_ADDRESS (Pmode, static_chain_rtx); |
ec907dd8 JL |
1443 | |
1444 | /* Walk the insns adding values to the new_reg_base_value array. */ | |
1445 | for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) | |
9ae8ffe7 | 1446 | { |
6e73e666 | 1447 | if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') |
ec907dd8 | 1448 | { |
6e73e666 | 1449 | rtx note, set; |
ec907dd8 JL |
1450 | /* If this insn has a noalias note, process it, Otherwise, |
1451 | scan for sets. A simple set will have no side effects | |
1452 | which could change the base value of any other register. */ | |
6e73e666 | 1453 | |
ec907dd8 | 1454 | if (GET_CODE (PATTERN (insn)) == SET |
6e73e666 | 1455 | && (find_reg_note (insn, REG_NOALIAS, NULL_RTX))) |
9f8f10de | 1456 | record_set (SET_DEST (PATTERN (insn)), NULL_RTX); |
ec907dd8 JL |
1457 | else |
1458 | note_stores (PATTERN (insn), record_set); | |
6e73e666 JC |
1459 | |
1460 | set = single_set (insn); | |
1461 | ||
1462 | if (set != 0 | |
1463 | && GET_CODE (SET_DEST (set)) == REG | |
1464 | && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER | |
1465 | && (((note = find_reg_note (insn, REG_EQUAL, 0)) != 0 | |
1466 | && REG_N_SETS (REGNO (SET_DEST (set))) == 1) | |
1467 | || (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != 0) | |
1468 | && GET_CODE (XEXP (note, 0)) != EXPR_LIST) | |
1469 | { | |
1470 | int regno = REGNO (SET_DEST (set)); | |
1471 | reg_known_value[regno] = XEXP (note, 0); | |
1472 | reg_known_equiv_p[regno] = REG_NOTE_KIND (note) == REG_EQUIV; | |
1473 | } | |
ec907dd8 JL |
1474 | } |
1475 | else if (GET_CODE (insn) == NOTE | |
1476 | && NOTE_LINE_NUMBER (insn) == NOTE_INSN_FUNCTION_BEG) | |
1477 | copying_arguments = 0; | |
6e73e666 | 1478 | } |
ec907dd8 | 1479 | |
6e73e666 | 1480 | /* Now propagate values from new_reg_base_value to reg_base_value. */ |
e51712db | 1481 | for (ui = 0; ui < reg_base_value_size; ui++) |
6e73e666 | 1482 | { |
e51712db KG |
1483 | if (new_reg_base_value[ui] |
1484 | && new_reg_base_value[ui] != reg_base_value[ui] | |
1485 | && ! rtx_equal_p (new_reg_base_value[ui], reg_base_value[ui])) | |
ec907dd8 | 1486 | { |
e51712db | 1487 | reg_base_value[ui] = new_reg_base_value[ui]; |
6e73e666 | 1488 | changed = 1; |
ec907dd8 | 1489 | } |
9ae8ffe7 | 1490 | } |
9ae8ffe7 | 1491 | } |
6e73e666 | 1492 | while (changed && ++pass < MAX_ALIAS_LOOP_PASSES); |
9ae8ffe7 JL |
1493 | |
1494 | /* Fill in the remaining entries. */ | |
1495 | for (i = FIRST_PSEUDO_REGISTER; i < maxreg; i++) | |
1496 | if (reg_known_value[i] == 0) | |
1497 | reg_known_value[i] = regno_reg_rtx[i]; | |
1498 | ||
9ae8ffe7 JL |
1499 | /* Simplify the reg_base_value array so that no register refers to |
1500 | another register, except to special registers indirectly through | |
1501 | ADDRESS expressions. | |
1502 | ||
1503 | In theory this loop can take as long as O(registers^2), but unless | |
1504 | there are very long dependency chains it will run in close to linear | |
ea64ef27 JL |
1505 | time. |
1506 | ||
1507 | This loop may not be needed any longer now that the main loop does | |
1508 | a better job at propagating alias information. */ | |
1509 | pass = 0; | |
9ae8ffe7 JL |
1510 | do |
1511 | { | |
1512 | changed = 0; | |
ea64ef27 | 1513 | pass++; |
e51712db | 1514 | for (ui = 0; ui < reg_base_value_size; ui++) |
9ae8ffe7 | 1515 | { |
e51712db | 1516 | rtx base = reg_base_value[ui]; |
9ae8ffe7 JL |
1517 | if (base && GET_CODE (base) == REG) |
1518 | { | |
e51712db KG |
1519 | unsigned int base_regno = REGNO (base); |
1520 | if (base_regno == ui) /* register set from itself */ | |
1521 | reg_base_value[ui] = 0; | |
9ae8ffe7 | 1522 | else |
e51712db | 1523 | reg_base_value[ui] = reg_base_value[base_regno]; |
9ae8ffe7 JL |
1524 | changed = 1; |
1525 | } | |
1526 | } | |
1527 | } | |
ea64ef27 | 1528 | while (changed && pass < MAX_ALIAS_LOOP_PASSES); |
9ae8ffe7 | 1529 | |
ec907dd8 | 1530 | new_reg_base_value = 0; |
9ae8ffe7 JL |
1531 | reg_seen = 0; |
1532 | } | |
1533 | ||
1534 | void | |
1535 | end_alias_analysis () | |
1536 | { | |
1537 | reg_known_value = 0; | |
1538 | reg_base_value = 0; | |
1539 | reg_base_value_size = 0; | |
de12be17 JC |
1540 | if (alias_invariant) |
1541 | { | |
1542 | free ((char *)alias_invariant); | |
1543 | alias_invariant = 0; | |
1544 | } | |
9ae8ffe7 | 1545 | } |