Mercurial > hg > CbC > CbC_gcc
annotate gcc/alias.c @ 19:58ad6c70ea60
update gcc from 4.4.0 to 4.4.1.
| author | kent@firefly.cr.ie.u-ryukyu.ac.jp |
|---|---|
| date | Thu, 24 Sep 2009 13:21:57 +0900 |
| parents | a06113de4d67 |
| children | 855418dad1a3 |
| rev | line source |
|---|---|
| 0 | 1 /* Alias analysis for GNU C |
| 2 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, | |
| 3 2007, 2008, 2009 Free Software Foundation, Inc. | |
| 4 Contributed by John Carr (jfc@mit.edu). | |
| 5 | |
| 6 This file is part of GCC. | |
| 7 | |
| 8 GCC is free software; you can redistribute it and/or modify it under | |
| 9 the terms of the GNU General Public License as published by the Free | |
| 10 Software Foundation; either version 3, or (at your option) any later | |
| 11 version. | |
| 12 | |
| 13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
| 14 WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 16 for more details. | |
| 17 | |
| 18 You should have received a copy of the GNU General Public License | |
| 19 along with GCC; see the file COPYING3. If not see | |
| 20 <http://www.gnu.org/licenses/>. */ | |
| 21 | |
| 22 #include "config.h" | |
| 23 #include "system.h" | |
| 24 #include "coretypes.h" | |
| 25 #include "tm.h" | |
| 26 #include "rtl.h" | |
| 27 #include "tree.h" | |
| 28 #include "tm_p.h" | |
| 29 #include "function.h" | |
| 30 #include "alias.h" | |
| 31 #include "emit-rtl.h" | |
| 32 #include "regs.h" | |
| 33 #include "hard-reg-set.h" | |
| 34 #include "basic-block.h" | |
| 35 #include "flags.h" | |
| 36 #include "output.h" | |
| 37 #include "toplev.h" | |
| 38 #include "cselib.h" | |
| 39 #include "splay-tree.h" | |
| 40 #include "ggc.h" | |
| 41 #include "langhooks.h" | |
| 42 #include "timevar.h" | |
| 43 #include "target.h" | |
| 44 #include "cgraph.h" | |
| 45 #include "varray.h" | |
| 46 #include "tree-pass.h" | |
| 47 #include "ipa-type-escape.h" | |
| 48 #include "df.h" | |
| 49 | |
| 50 /* The aliasing API provided here solves related but different problems: | |
| 51 | |
| 52 Say there exists (in c) | |
| 53 | |
| 54 struct X { | |
| 55 struct Y y1; | |
| 56 struct Z z2; | |
| 57 } x1, *px1, *px2; | |
| 58 | |
| 59 struct Y y2, *py; | |
| 60 struct Z z2, *pz; | |
| 61 | |
| 62 | |
| 63 py = &px1.y1; | |
| 64 px2 = &x1; | |
| 65 | |
| 66 Consider the four questions: | |
| 67 | |
| 68 Can a store to x1 interfere with px2->y1? | |
| 69 Can a store to x1 interfere with px2->z2? | |
| 70 (*px2).z2 | |
| 71 Can a store to x1 change the value pointed to by with py? | |
| 72 Can a store to x1 change the value pointed to by with pz? | |
| 73 | |
| 74 The answer to these questions can be yes, yes, yes, and maybe. | |
| 75 | |
| 76 The first two questions can be answered with a simple examination | |
| 77 of the type system. If structure X contains a field of type Y then | |
| 78 a store thru a pointer to an X can overwrite any field that is | |
| 79 contained (recursively) in an X (unless we know that px1 != px2). | |
| 80 | |
| 81 The last two of the questions can be solved in the same way as the | |
| 82 first two questions but this is too conservative. The observation | |
| 83 is that in some cases analysis we can know if which (if any) fields | |
| 84 are addressed and if those addresses are used in bad ways. This | |
| 85 analysis may be language specific. In C, arbitrary operations may | |
| 86 be applied to pointers. However, there is some indication that | |
| 87 this may be too conservative for some C++ types. | |
| 88 | |
| 89 The pass ipa-type-escape does this analysis for the types whose | |
| 90 instances do not escape across the compilation boundary. | |
| 91 | |
| 92 Historically in GCC, these two problems were combined and a single | |
| 93 data structure was used to represent the solution to these | |
| 94 problems. We now have two similar but different data structures, | |
| 95 The data structure to solve the last two question is similar to the | |
| 96 first, but does not contain have the fields in it whose address are | |
| 97 never taken. For types that do escape the compilation unit, the | |
| 98 data structures will have identical information. | |
| 99 */ | |
| 100 | |
| 101 /* The alias sets assigned to MEMs assist the back-end in determining | |
| 102 which MEMs can alias which other MEMs. In general, two MEMs in | |
| 103 different alias sets cannot alias each other, with one important | |
| 104 exception. Consider something like: | |
| 105 | |
| 106 struct S { int i; double d; }; | |
| 107 | |
| 108 a store to an `S' can alias something of either type `int' or type | |
| 109 `double'. (However, a store to an `int' cannot alias a `double' | |
| 110 and vice versa.) We indicate this via a tree structure that looks | |
| 111 like: | |
| 112 struct S | |
| 113 / \ | |
| 114 / \ | |
| 115 |/_ _\| | |
| 116 int double | |
| 117 | |
| 118 (The arrows are directed and point downwards.) | |
| 119 In this situation we say the alias set for `struct S' is the | |
| 120 `superset' and that those for `int' and `double' are `subsets'. | |
| 121 | |
| 122 To see whether two alias sets can point to the same memory, we must | |
| 123 see if either alias set is a subset of the other. We need not trace | |
| 124 past immediate descendants, however, since we propagate all | |
| 125 grandchildren up one level. | |
| 126 | |
| 127 Alias set zero is implicitly a superset of all other alias sets. | |
| 128 However, this is no actual entry for alias set zero. It is an | |
| 129 error to attempt to explicitly construct a subset of zero. */ | |
| 130 | |
| 131 struct alias_set_entry GTY(()) | |
| 132 { | |
| 133 /* The alias set number, as stored in MEM_ALIAS_SET. */ | |
| 134 alias_set_type alias_set; | |
| 135 | |
| 136 /* Nonzero if would have a child of zero: this effectively makes this | |
| 137 alias set the same as alias set zero. */ | |
| 138 int has_zero_child; | |
| 139 | |
| 140 /* The children of the alias set. These are not just the immediate | |
| 141 children, but, in fact, all descendants. So, if we have: | |
| 142 | |
| 143 struct T { struct S s; float f; } | |
| 144 | |
| 145 continuing our example above, the children here will be all of | |
| 146 `int', `double', `float', and `struct S'. */ | |
| 147 splay_tree GTY((param1_is (int), param2_is (int))) children; | |
| 148 }; | |
| 149 typedef struct alias_set_entry *alias_set_entry; | |
| 150 | |
| 151 static int rtx_equal_for_memref_p (const_rtx, const_rtx); | |
| 152 static int memrefs_conflict_p (int, rtx, int, rtx, HOST_WIDE_INT); | |
| 153 static void record_set (rtx, const_rtx, void *); | |
| 154 static int base_alias_check (rtx, rtx, enum machine_mode, | |
| 155 enum machine_mode); | |
| 156 static rtx find_base_value (rtx); | |
| 157 static int mems_in_disjoint_alias_sets_p (const_rtx, const_rtx); | |
| 158 static int insert_subset_children (splay_tree_node, void*); | |
| 159 static tree find_base_decl (tree); | |
| 160 static alias_set_entry get_alias_set_entry (alias_set_type); | |
| 161 static const_rtx fixed_scalar_and_varying_struct_p (const_rtx, const_rtx, rtx, rtx, | |
| 162 bool (*) (const_rtx, bool)); | |
| 163 static int aliases_everything_p (const_rtx); | |
| 164 static bool nonoverlapping_component_refs_p (const_tree, const_tree); | |
| 165 static tree decl_for_component_ref (tree); | |
| 166 static rtx adjust_offset_for_component_ref (tree, rtx); | |
| 167 static int write_dependence_p (const_rtx, const_rtx, int); | |
| 168 | |
| 169 static void memory_modified_1 (rtx, const_rtx, void *); | |
| 170 | |
| 171 /* Set up all info needed to perform alias analysis on memory references. */ | |
| 172 | |
| 173 /* Returns the size in bytes of the mode of X. */ | |
| 174 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X))) | |
| 175 | |
| 176 /* Returns nonzero if MEM1 and MEM2 do not alias because they are in | |
| 177 different alias sets. We ignore alias sets in functions making use | |
| 178 of variable arguments because the va_arg macros on some systems are | |
| 179 not legal ANSI C. */ | |
| 180 #define DIFFERENT_ALIAS_SETS_P(MEM1, MEM2) \ | |
| 181 mems_in_disjoint_alias_sets_p (MEM1, MEM2) | |
| 182 | |
| 183 /* Cap the number of passes we make over the insns propagating alias | |
| 184 information through set chains. 10 is a completely arbitrary choice. */ | |
| 185 #define MAX_ALIAS_LOOP_PASSES 10 | |
| 186 | |
| 187 /* reg_base_value[N] gives an address to which register N is related. | |
| 188 If all sets after the first add or subtract to the current value | |
| 189 or otherwise modify it so it does not point to a different top level | |
| 190 object, reg_base_value[N] is equal to the address part of the source | |
| 191 of the first set. | |
| 192 | |
| 193 A base address can be an ADDRESS, SYMBOL_REF, or LABEL_REF. ADDRESS | |
| 194 expressions represent certain special values: function arguments and | |
| 195 the stack, frame, and argument pointers. | |
| 196 | |
| 197 The contents of an ADDRESS is not normally used, the mode of the | |
| 198 ADDRESS determines whether the ADDRESS is a function argument or some | |
| 199 other special value. Pointer equality, not rtx_equal_p, determines whether | |
| 200 two ADDRESS expressions refer to the same base address. | |
| 201 | |
| 202 The only use of the contents of an ADDRESS is for determining if the | |
| 203 current function performs nonlocal memory memory references for the | |
| 204 purposes of marking the function as a constant function. */ | |
| 205 | |
| 206 static GTY(()) VEC(rtx,gc) *reg_base_value; | |
| 207 static rtx *new_reg_base_value; | |
| 208 | |
| 209 /* We preserve the copy of old array around to avoid amount of garbage | |
| 210 produced. About 8% of garbage produced were attributed to this | |
| 211 array. */ | |
| 212 static GTY((deletable)) VEC(rtx,gc) *old_reg_base_value; | |
| 213 | |
| 214 /* Static hunks of RTL used by the aliasing code; these are initialized | |
| 215 once per function to avoid unnecessary RTL allocations. */ | |
| 216 static GTY (()) rtx static_reg_base_value[FIRST_PSEUDO_REGISTER]; | |
| 217 | |
| 218 #define REG_BASE_VALUE(X) \ | |
| 219 (REGNO (X) < VEC_length (rtx, reg_base_value) \ | |
| 220 ? VEC_index (rtx, reg_base_value, REGNO (X)) : 0) | |
| 221 | |
| 222 /* Vector indexed by N giving the initial (unchanging) value known for | |
| 223 pseudo-register N. This array is initialized in init_alias_analysis, | |
| 224 and does not change until end_alias_analysis is called. */ | |
| 225 static GTY((length("reg_known_value_size"))) rtx *reg_known_value; | |
| 226 | |
| 227 /* Indicates number of valid entries in reg_known_value. */ | |
| 228 static GTY(()) unsigned int reg_known_value_size; | |
| 229 | |
| 230 /* Vector recording for each reg_known_value whether it is due to a | |
| 231 REG_EQUIV note. Future passes (viz., reload) may replace the | |
| 232 pseudo with the equivalent expression and so we account for the | |
| 233 dependences that would be introduced if that happens. | |
| 234 | |
| 235 The REG_EQUIV notes created in assign_parms may mention the arg | |
| 236 pointer, and there are explicit insns in the RTL that modify the | |
| 237 arg pointer. Thus we must ensure that such insns don't get | |
| 238 scheduled across each other because that would invalidate the | |
| 239 REG_EQUIV notes. One could argue that the REG_EQUIV notes are | |
| 240 wrong, but solving the problem in the scheduler will likely give | |
| 241 better code, so we do it here. */ | |
| 242 static bool *reg_known_equiv_p; | |
| 243 | |
| 244 /* True when scanning insns from the start of the rtl to the | |
| 245 NOTE_INSN_FUNCTION_BEG note. */ | |
| 246 static bool copying_arguments; | |
| 247 | |
| 248 DEF_VEC_P(alias_set_entry); | |
| 249 DEF_VEC_ALLOC_P(alias_set_entry,gc); | |
| 250 | |
| 251 /* The splay-tree used to store the various alias set entries. */ | |
| 252 static GTY (()) VEC(alias_set_entry,gc) *alias_sets; | |
| 253 | |
| 254 /* Returns a pointer to the alias set entry for ALIAS_SET, if there is | |
| 255 such an entry, or NULL otherwise. */ | |
| 256 | |
| 257 static inline alias_set_entry | |
| 258 get_alias_set_entry (alias_set_type alias_set) | |
| 259 { | |
| 260 return VEC_index (alias_set_entry, alias_sets, alias_set); | |
| 261 } | |
| 262 | |
| 263 /* Returns nonzero if the alias sets for MEM1 and MEM2 are such that | |
| 264 the two MEMs cannot alias each other. */ | |
| 265 | |
| 266 static inline int | |
| 267 mems_in_disjoint_alias_sets_p (const_rtx mem1, const_rtx mem2) | |
| 268 { | |
| 269 /* Perform a basic sanity check. Namely, that there are no alias sets | |
| 270 if we're not using strict aliasing. This helps to catch bugs | |
| 271 whereby someone uses PUT_CODE, but doesn't clear MEM_ALIAS_SET, or | |
| 272 where a MEM is allocated in some way other than by the use of | |
| 273 gen_rtx_MEM, and the MEM_ALIAS_SET is not cleared. If we begin to | |
| 274 use alias sets to indicate that spilled registers cannot alias each | |
| 275 other, we might need to remove this check. */ | |
| 276 gcc_assert (flag_strict_aliasing | |
| 277 || (!MEM_ALIAS_SET (mem1) && !MEM_ALIAS_SET (mem2))); | |
| 278 | |
| 279 return ! alias_sets_conflict_p (MEM_ALIAS_SET (mem1), MEM_ALIAS_SET (mem2)); | |
| 280 } | |
| 281 | |
| 282 /* Insert the NODE into the splay tree given by DATA. Used by | |
| 283 record_alias_subset via splay_tree_foreach. */ | |
| 284 | |
| 285 static int | |
| 286 insert_subset_children (splay_tree_node node, void *data) | |
| 287 { | |
| 288 splay_tree_insert ((splay_tree) data, node->key, node->value); | |
| 289 | |
| 290 return 0; | |
| 291 } | |
| 292 | |
| 293 /* Return true if the first alias set is a subset of the second. */ | |
| 294 | |
| 295 bool | |
| 296 alias_set_subset_of (alias_set_type set1, alias_set_type set2) | |
| 297 { | |
| 298 alias_set_entry ase; | |
| 299 | |
| 300 /* Everything is a subset of the "aliases everything" set. */ | |
| 301 if (set2 == 0) | |
| 302 return true; | |
| 303 | |
| 304 /* Otherwise, check if set1 is a subset of set2. */ | |
| 305 ase = get_alias_set_entry (set2); | |
| 306 if (ase != 0 | |
| 307 && ((ase->has_zero_child && set1 == 0) | |
| 308 || splay_tree_lookup (ase->children, | |
| 309 (splay_tree_key) set1))) | |
| 310 return true; | |
| 311 return false; | |
| 312 } | |
| 313 | |
| 314 /* Return 1 if the two specified alias sets may conflict. */ | |
| 315 | |
| 316 int | |
| 317 alias_sets_conflict_p (alias_set_type set1, alias_set_type set2) | |
| 318 { | |
| 319 alias_set_entry ase; | |
| 320 | |
| 321 /* The easy case. */ | |
| 322 if (alias_sets_must_conflict_p (set1, set2)) | |
| 323 return 1; | |
| 324 | |
| 325 /* See if the first alias set is a subset of the second. */ | |
| 326 ase = get_alias_set_entry (set1); | |
| 327 if (ase != 0 | |
| 328 && (ase->has_zero_child | |
| 329 || splay_tree_lookup (ase->children, | |
| 330 (splay_tree_key) set2))) | |
| 331 return 1; | |
| 332 | |
| 333 /* Now do the same, but with the alias sets reversed. */ | |
| 334 ase = get_alias_set_entry (set2); | |
| 335 if (ase != 0 | |
| 336 && (ase->has_zero_child | |
| 337 || splay_tree_lookup (ase->children, | |
| 338 (splay_tree_key) set1))) | |
| 339 return 1; | |
| 340 | |
| 341 /* The two alias sets are distinct and neither one is the | |
| 342 child of the other. Therefore, they cannot conflict. */ | |
| 343 return 0; | |
| 344 } | |
| 345 | |
| 346 static int | |
| 347 walk_mems_2 (rtx *x, rtx mem) | |
| 348 { | |
| 349 if (MEM_P (*x)) | |
| 350 { | |
| 351 if (alias_sets_conflict_p (MEM_ALIAS_SET(*x), MEM_ALIAS_SET(mem))) | |
| 352 return 1; | |
| 353 | |
| 354 return -1; | |
| 355 } | |
| 356 return 0; | |
| 357 } | |
| 358 | |
| 359 static int | |
| 360 walk_mems_1 (rtx *x, rtx *pat) | |
| 361 { | |
| 362 if (MEM_P (*x)) | |
| 363 { | |
| 364 /* Visit all MEMs in *PAT and check indepedence. */ | |
| 365 if (for_each_rtx (pat, (rtx_function) walk_mems_2, *x)) | |
| 366 /* Indicate that dependence was determined and stop traversal. */ | |
| 367 return 1; | |
| 368 | |
| 369 return -1; | |
| 370 } | |
| 371 return 0; | |
| 372 } | |
| 373 | |
| 374 /* Return 1 if two specified instructions have mem expr with conflict alias sets*/ | |
| 375 bool | |
| 376 insn_alias_sets_conflict_p (rtx insn1, rtx insn2) | |
| 377 { | |
| 378 /* For each pair of MEMs in INSN1 and INSN2 check their independence. */ | |
| 379 return for_each_rtx (&PATTERN (insn1), (rtx_function) walk_mems_1, | |
| 380 &PATTERN (insn2)); | |
| 381 } | |
| 382 | |
| 383 /* Return 1 if the two specified alias sets will always conflict. */ | |
| 384 | |
| 385 int | |
| 386 alias_sets_must_conflict_p (alias_set_type set1, alias_set_type set2) | |
| 387 { | |
| 388 if (set1 == 0 || set2 == 0 || set1 == set2) | |
| 389 return 1; | |
| 390 | |
| 391 return 0; | |
| 392 } | |
| 393 | |
| 394 /* Return 1 if any MEM object of type T1 will always conflict (using the | |
| 395 dependency routines in this file) with any MEM object of type T2. | |
| 396 This is used when allocating temporary storage. If T1 and/or T2 are | |
| 397 NULL_TREE, it means we know nothing about the storage. */ | |
| 398 | |
| 399 int | |
| 400 objects_must_conflict_p (tree t1, tree t2) | |
| 401 { | |
| 402 alias_set_type set1, set2; | |
| 403 | |
| 404 /* If neither has a type specified, we don't know if they'll conflict | |
| 405 because we may be using them to store objects of various types, for | |
| 406 example the argument and local variables areas of inlined functions. */ | |
| 407 if (t1 == 0 && t2 == 0) | |
| 408 return 0; | |
| 409 | |
| 410 /* If they are the same type, they must conflict. */ | |
| 411 if (t1 == t2 | |
| 412 /* Likewise if both are volatile. */ | |
| 413 || (t1 != 0 && TYPE_VOLATILE (t1) && t2 != 0 && TYPE_VOLATILE (t2))) | |
| 414 return 1; | |
| 415 | |
| 416 set1 = t1 ? get_alias_set (t1) : 0; | |
| 417 set2 = t2 ? get_alias_set (t2) : 0; | |
| 418 | |
| 419 /* We can't use alias_sets_conflict_p because we must make sure | |
| 420 that every subtype of t1 will conflict with every subtype of | |
| 421 t2 for which a pair of subobjects of these respective subtypes | |
| 422 overlaps on the stack. */ | |
| 423 return alias_sets_must_conflict_p (set1, set2); | |
| 424 } | |
| 425 | |
| 426 /* T is an expression with pointer type. Find the DECL on which this | |
| 427 expression is based. (For example, in `a[i]' this would be `a'.) | |
| 428 If there is no such DECL, or a unique decl cannot be determined, | |
| 429 NULL_TREE is returned. */ | |
| 430 | |
| 431 static tree | |
| 432 find_base_decl (tree t) | |
| 433 { | |
| 434 tree d0, d1; | |
| 435 | |
| 436 if (t == 0 || t == error_mark_node || ! POINTER_TYPE_P (TREE_TYPE (t))) | |
| 437 return 0; | |
| 438 | |
| 439 /* If this is a declaration, return it. If T is based on a restrict | |
| 440 qualified decl, return that decl. */ | |
| 441 if (DECL_P (t)) | |
| 442 { | |
| 443 if (TREE_CODE (t) == VAR_DECL && DECL_BASED_ON_RESTRICT_P (t)) | |
| 444 t = DECL_GET_RESTRICT_BASE (t); | |
| 445 return t; | |
| 446 } | |
| 447 | |
| 448 /* Handle general expressions. It would be nice to deal with | |
| 449 COMPONENT_REFs here. If we could tell that `a' and `b' were the | |
| 450 same, then `a->f' and `b->f' are also the same. */ | |
| 451 switch (TREE_CODE_CLASS (TREE_CODE (t))) | |
| 452 { | |
| 453 case tcc_unary: | |
| 454 return find_base_decl (TREE_OPERAND (t, 0)); | |
| 455 | |
| 456 case tcc_binary: | |
| 457 /* Return 0 if found in neither or both are the same. */ | |
| 458 d0 = find_base_decl (TREE_OPERAND (t, 0)); | |
| 459 d1 = find_base_decl (TREE_OPERAND (t, 1)); | |
| 460 if (d0 == d1) | |
| 461 return d0; | |
| 462 else if (d0 == 0) | |
| 463 return d1; | |
| 464 else if (d1 == 0) | |
| 465 return d0; | |
| 466 else | |
| 467 return 0; | |
| 468 | |
| 469 default: | |
| 470 return 0; | |
| 471 } | |
| 472 } | |
| 473 | |
| 474 /* Return true if all nested component references handled by | |
| 475 get_inner_reference in T are such that we should use the alias set | |
| 476 provided by the object at the heart of T. | |
| 477 | |
| 478 This is true for non-addressable components (which don't have their | |
| 479 own alias set), as well as components of objects in alias set zero. | |
| 480 This later point is a special case wherein we wish to override the | |
| 481 alias set used by the component, but we don't have per-FIELD_DECL | |
| 482 assignable alias sets. */ | |
| 483 | |
| 484 bool | |
| 485 component_uses_parent_alias_set (const_tree t) | |
| 486 { | |
| 487 while (1) | |
| 488 { | |
| 489 /* If we're at the end, it vacuously uses its own alias set. */ | |
| 490 if (!handled_component_p (t)) | |
| 491 return false; | |
| 492 | |
| 493 switch (TREE_CODE (t)) | |
| 494 { | |
| 495 case COMPONENT_REF: | |
| 496 if (DECL_NONADDRESSABLE_P (TREE_OPERAND (t, 1))) | |
| 497 return true; | |
| 498 break; | |
| 499 | |
| 500 case ARRAY_REF: | |
| 501 case ARRAY_RANGE_REF: | |
| 502 if (TYPE_NONALIASED_COMPONENT (TREE_TYPE (TREE_OPERAND (t, 0)))) | |
| 503 return true; | |
| 504 break; | |
| 505 | |
| 506 case REALPART_EXPR: | |
| 507 case IMAGPART_EXPR: | |
| 508 break; | |
| 509 | |
| 510 default: | |
| 511 /* Bitfields and casts are never addressable. */ | |
| 512 return true; | |
| 513 } | |
| 514 | |
| 515 t = TREE_OPERAND (t, 0); | |
| 516 if (get_alias_set (TREE_TYPE (t)) == 0) | |
| 517 return true; | |
| 518 } | |
| 519 } | |
| 520 | |
| 521 /* Return the alias set for T, which may be either a type or an | |
| 522 expression. Call language-specific routine for help, if needed. */ | |
| 523 | |
| 524 alias_set_type | |
| 525 get_alias_set (tree t) | |
| 526 { | |
| 527 alias_set_type set; | |
| 528 | |
| 529 /* If we're not doing any alias analysis, just assume everything | |
| 530 aliases everything else. Also return 0 if this or its type is | |
| 531 an error. */ | |
| 532 if (! flag_strict_aliasing || t == error_mark_node | |
| 533 || (! TYPE_P (t) | |
| 534 && (TREE_TYPE (t) == 0 || TREE_TYPE (t) == error_mark_node))) | |
| 535 return 0; | |
| 536 | |
| 537 /* We can be passed either an expression or a type. This and the | |
| 538 language-specific routine may make mutually-recursive calls to each other | |
| 539 to figure out what to do. At each juncture, we see if this is a tree | |
| 540 that the language may need to handle specially. First handle things that | |
| 541 aren't types. */ | |
| 542 if (! TYPE_P (t)) | |
| 543 { | |
| 544 tree inner = t; | |
| 545 | |
| 546 /* Remove any nops, then give the language a chance to do | |
| 547 something with this tree before we look at it. */ | |
| 548 STRIP_NOPS (t); | |
| 549 set = lang_hooks.get_alias_set (t); | |
| 550 if (set != -1) | |
| 551 return set; | |
| 552 | |
| 553 /* First see if the actual object referenced is an INDIRECT_REF from a | |
| 554 restrict-qualified pointer or a "void *". */ | |
| 555 while (handled_component_p (inner)) | |
| 556 { | |
| 557 inner = TREE_OPERAND (inner, 0); | |
| 558 STRIP_NOPS (inner); | |
| 559 } | |
| 560 | |
| 561 /* Check for accesses through restrict-qualified pointers. */ | |
| 562 if (INDIRECT_REF_P (inner)) | |
| 563 { | |
| 564 tree decl; | |
| 565 | |
| 566 if (TREE_CODE (TREE_OPERAND (inner, 0)) == SSA_NAME) | |
| 567 decl = SSA_NAME_VAR (TREE_OPERAND (inner, 0)); | |
| 568 else | |
| 569 decl = find_base_decl (TREE_OPERAND (inner, 0)); | |
| 570 | |
| 571 if (decl && DECL_POINTER_ALIAS_SET_KNOWN_P (decl)) | |
| 572 { | |
| 573 /* If we haven't computed the actual alias set, do it now. */ | |
| 574 if (DECL_POINTER_ALIAS_SET (decl) == -2) | |
| 575 { | |
| 576 tree pointed_to_type = TREE_TYPE (TREE_TYPE (decl)); | |
| 577 | |
| 578 /* No two restricted pointers can point at the same thing. | |
| 579 However, a restricted pointer can point at the same thing | |
| 580 as an unrestricted pointer, if that unrestricted pointer | |
| 581 is based on the restricted pointer. So, we make the | |
| 582 alias set for the restricted pointer a subset of the | |
| 583 alias set for the type pointed to by the type of the | |
| 584 decl. */ | |
| 585 alias_set_type pointed_to_alias_set | |
| 586 = get_alias_set (pointed_to_type); | |
| 587 | |
| 588 if (pointed_to_alias_set == 0) | |
| 589 /* It's not legal to make a subset of alias set zero. */ | |
| 590 DECL_POINTER_ALIAS_SET (decl) = 0; | |
| 591 else if (AGGREGATE_TYPE_P (pointed_to_type)) | |
| 592 /* For an aggregate, we must treat the restricted | |
| 593 pointer the same as an ordinary pointer. If we | |
| 594 were to make the type pointed to by the | |
| 595 restricted pointer a subset of the pointed-to | |
| 596 type, then we would believe that other subsets | |
| 597 of the pointed-to type (such as fields of that | |
| 598 type) do not conflict with the type pointed to | |
| 599 by the restricted pointer. */ | |
| 600 DECL_POINTER_ALIAS_SET (decl) | |
| 601 = pointed_to_alias_set; | |
| 602 else | |
| 603 { | |
| 604 DECL_POINTER_ALIAS_SET (decl) = new_alias_set (); | |
| 605 record_alias_subset (pointed_to_alias_set, | |
| 606 DECL_POINTER_ALIAS_SET (decl)); | |
| 607 } | |
| 608 } | |
| 609 | |
| 610 /* We use the alias set indicated in the declaration. */ | |
| 611 return DECL_POINTER_ALIAS_SET (decl); | |
| 612 } | |
| 613 | |
| 614 /* If we have an INDIRECT_REF via a void pointer, we don't | |
| 615 know anything about what that might alias. Likewise if the | |
| 616 pointer is marked that way. */ | |
| 617 else if (TREE_CODE (TREE_TYPE (inner)) == VOID_TYPE | |
| 618 || (TYPE_REF_CAN_ALIAS_ALL | |
| 619 (TREE_TYPE (TREE_OPERAND (inner, 0))))) | |
| 620 return 0; | |
| 621 } | |
| 622 | |
| 623 /* Otherwise, pick up the outermost object that we could have a pointer | |
| 624 to, processing conversions as above. */ | |
| 625 while (component_uses_parent_alias_set (t)) | |
| 626 { | |
| 627 t = TREE_OPERAND (t, 0); | |
| 628 STRIP_NOPS (t); | |
| 629 } | |
| 630 | |
| 631 /* If we've already determined the alias set for a decl, just return | |
| 632 it. This is necessary for C++ anonymous unions, whose component | |
| 633 variables don't look like union members (boo!). */ | |
| 634 if (TREE_CODE (t) == VAR_DECL | |
| 635 && DECL_RTL_SET_P (t) && MEM_P (DECL_RTL (t))) | |
| 636 return MEM_ALIAS_SET (DECL_RTL (t)); | |
| 637 | |
| 638 /* Now all we care about is the type. */ | |
| 639 t = TREE_TYPE (t); | |
| 640 } | |
| 641 | |
| 642 /* Variant qualifiers don't affect the alias set, so get the main | |
| 643 variant. Always use the canonical type as well. | |
| 644 If this is a type with a known alias set, return it. */ | |
| 645 t = TYPE_MAIN_VARIANT (t); | |
| 646 if (TYPE_CANONICAL (t)) | |
| 647 t = TYPE_CANONICAL (t); | |
| 648 if (TYPE_ALIAS_SET_KNOWN_P (t)) | |
| 649 return TYPE_ALIAS_SET (t); | |
| 650 | |
| 651 /* We don't want to set TYPE_ALIAS_SET for incomplete types. */ | |
| 652 if (!COMPLETE_TYPE_P (t)) | |
| 653 { | |
| 654 /* For arrays with unknown size the conservative answer is the | |
| 655 alias set of the element type. */ | |
| 656 if (TREE_CODE (t) == ARRAY_TYPE) | |
| 657 return get_alias_set (TREE_TYPE (t)); | |
| 658 | |
| 659 /* But return zero as a conservative answer for incomplete types. */ | |
| 660 return 0; | |
| 661 } | |
| 662 | |
| 663 /* See if the language has special handling for this type. */ | |
| 664 set = lang_hooks.get_alias_set (t); | |
| 665 if (set != -1) | |
| 666 return set; | |
| 667 | |
| 668 /* There are no objects of FUNCTION_TYPE, so there's no point in | |
| 669 using up an alias set for them. (There are, of course, pointers | |
| 670 and references to functions, but that's different.) */ | |
| 671 else if (TREE_CODE (t) == FUNCTION_TYPE | |
| 672 || TREE_CODE (t) == METHOD_TYPE) | |
| 673 set = 0; | |
| 674 | |
| 675 /* Unless the language specifies otherwise, let vector types alias | |
| 676 their components. This avoids some nasty type punning issues in | |
| 677 normal usage. And indeed lets vectors be treated more like an | |
| 678 array slice. */ | |
| 679 else if (TREE_CODE (t) == VECTOR_TYPE) | |
| 680 set = get_alias_set (TREE_TYPE (t)); | |
| 681 | |
| 682 /* Unless the language specifies otherwise, treat array types the | |
| 683 same as their components. This avoids the asymmetry we get | |
| 684 through recording the components. Consider accessing a | |
| 685 character(kind=1) through a reference to a character(kind=1)[1:1]. | |
| 686 Or consider if we want to assign integer(kind=4)[0:D.1387] and | |
| 687 integer(kind=4)[4] the same alias set or not. | |
| 688 Just be pragmatic here and make sure the array and its element | |
| 689 type get the same alias set assigned. */ | |
| 690 else if (TREE_CODE (t) == ARRAY_TYPE | |
| 691 && !TYPE_NONALIASED_COMPONENT (t)) | |
| 692 set = get_alias_set (TREE_TYPE (t)); | |
| 693 | |
| 694 else | |
| 695 /* Otherwise make a new alias set for this type. */ | |
| 696 set = new_alias_set (); | |
| 697 | |
| 698 TYPE_ALIAS_SET (t) = set; | |
| 699 | |
| 700 /* If this is an aggregate type, we must record any component aliasing | |
| 701 information. */ | |
| 702 if (AGGREGATE_TYPE_P (t) || TREE_CODE (t) == COMPLEX_TYPE) | |
| 703 record_component_aliases (t); | |
| 704 | |
| 705 return set; | |
| 706 } | |
| 707 | |
| 708 /* Return a brand-new alias set. */ | |
| 709 | |
| 710 alias_set_type | |
| 711 new_alias_set (void) | |
| 712 { | |
| 713 if (flag_strict_aliasing) | |
| 714 { | |
| 715 if (alias_sets == 0) | |
| 716 VEC_safe_push (alias_set_entry, gc, alias_sets, 0); | |
| 717 VEC_safe_push (alias_set_entry, gc, alias_sets, 0); | |
| 718 return VEC_length (alias_set_entry, alias_sets) - 1; | |
| 719 } | |
| 720 else | |
| 721 return 0; | |
| 722 } | |
| 723 | |
| 724 /* Indicate that things in SUBSET can alias things in SUPERSET, but that | |
| 725 not everything that aliases SUPERSET also aliases SUBSET. For example, | |
| 726 in C, a store to an `int' can alias a load of a structure containing an | |
| 727 `int', and vice versa. But it can't alias a load of a 'double' member | |
| 728 of the same structure. Here, the structure would be the SUPERSET and | |
| 729 `int' the SUBSET. This relationship is also described in the comment at | |
| 730 the beginning of this file. | |
| 731 | |
| 732 This function should be called only once per SUPERSET/SUBSET pair. | |
| 733 | |
| 734 It is illegal for SUPERSET to be zero; everything is implicitly a | |
| 735 subset of alias set zero. */ | |
| 736 | |
| 737 void | |
| 738 record_alias_subset (alias_set_type superset, alias_set_type subset) | |
| 739 { | |
| 740 alias_set_entry superset_entry; | |
| 741 alias_set_entry subset_entry; | |
| 742 | |
| 743 /* It is possible in complex type situations for both sets to be the same, | |
| 744 in which case we can ignore this operation. */ | |
| 745 if (superset == subset) | |
| 746 return; | |
| 747 | |
| 748 gcc_assert (superset); | |
| 749 | |
| 750 superset_entry = get_alias_set_entry (superset); | |
| 751 if (superset_entry == 0) | |
| 752 { | |
| 753 /* Create an entry for the SUPERSET, so that we have a place to | |
| 754 attach the SUBSET. */ | |
| 755 superset_entry = GGC_NEW (struct alias_set_entry); | |
| 756 superset_entry->alias_set = superset; | |
| 757 superset_entry->children | |
| 758 = splay_tree_new_ggc (splay_tree_compare_ints); | |
| 759 superset_entry->has_zero_child = 0; | |
| 760 VEC_replace (alias_set_entry, alias_sets, superset, superset_entry); | |
| 761 } | |
| 762 | |
| 763 if (subset == 0) | |
| 764 superset_entry->has_zero_child = 1; | |
| 765 else | |
| 766 { | |
| 767 subset_entry = get_alias_set_entry (subset); | |
| 768 /* If there is an entry for the subset, enter all of its children | |
| 769 (if they are not already present) as children of the SUPERSET. */ | |
| 770 if (subset_entry) | |
| 771 { | |
| 772 if (subset_entry->has_zero_child) | |
| 773 superset_entry->has_zero_child = 1; | |
| 774 | |
| 775 splay_tree_foreach (subset_entry->children, insert_subset_children, | |
| 776 superset_entry->children); | |
| 777 } | |
| 778 | |
| 779 /* Enter the SUBSET itself as a child of the SUPERSET. */ | |
| 780 splay_tree_insert (superset_entry->children, | |
| 781 (splay_tree_key) subset, 0); | |
| 782 } | |
| 783 } | |
| 784 | |
| 785 /* Record that component types of TYPE, if any, are part of that type for | |
| 786 aliasing purposes. For record types, we only record component types | |
| 787 for fields that are not marked non-addressable. For array types, we | |
| 788 only record the component type if it is not marked non-aliased. */ | |
| 789 | |
| 790 void | |
| 791 record_component_aliases (tree type) | |
| 792 { | |
| 793 alias_set_type superset = get_alias_set (type); | |
| 794 tree field; | |
| 795 | |
| 796 if (superset == 0) | |
| 797 return; | |
| 798 | |
| 799 switch (TREE_CODE (type)) | |
| 800 { | |
| 801 case RECORD_TYPE: | |
| 802 case UNION_TYPE: | |
| 803 case QUAL_UNION_TYPE: | |
| 804 /* Recursively record aliases for the base classes, if there are any. */ | |
| 805 if (TYPE_BINFO (type)) | |
| 806 { | |
| 807 int i; | |
| 808 tree binfo, base_binfo; | |
| 809 | |
| 810 for (binfo = TYPE_BINFO (type), i = 0; | |
| 811 BINFO_BASE_ITERATE (binfo, i, base_binfo); i++) | |
| 812 record_alias_subset (superset, | |
| 813 get_alias_set (BINFO_TYPE (base_binfo))); | |
| 814 } | |
| 815 for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field)) | |
| 816 if (TREE_CODE (field) == FIELD_DECL && !DECL_NONADDRESSABLE_P (field)) | |
| 817 record_alias_subset (superset, get_alias_set (TREE_TYPE (field))); | |
| 818 break; | |
| 819 | |
| 820 case COMPLEX_TYPE: | |
| 821 record_alias_subset (superset, get_alias_set (TREE_TYPE (type))); | |
| 822 break; | |
| 823 | |
| 824 /* VECTOR_TYPE and ARRAY_TYPE share the alias set with their | |
| 825 element type. */ | |
| 826 | |
| 827 default: | |
| 828 break; | |
| 829 } | |
| 830 } | |
| 831 | |
| 832 /* Allocate an alias set for use in storing and reading from the varargs | |
| 833 spill area. */ | |
| 834 | |
| 835 static GTY(()) alias_set_type varargs_set = -1; | |
| 836 | |
| 837 alias_set_type | |
| 838 get_varargs_alias_set (void) | |
| 839 { | |
| 840 #if 1 | |
| 841 /* We now lower VA_ARG_EXPR, and there's currently no way to attach the | |
| 842 varargs alias set to an INDIRECT_REF (FIXME!), so we can't | |
| 843 consistently use the varargs alias set for loads from the varargs | |
| 844 area. So don't use it anywhere. */ | |
| 845 return 0; | |
| 846 #else | |
| 847 if (varargs_set == -1) | |
| 848 varargs_set = new_alias_set (); | |
| 849 | |
| 850 return varargs_set; | |
| 851 #endif | |
| 852 } | |
| 853 | |
| 854 /* Likewise, but used for the fixed portions of the frame, e.g., register | |
| 855 save areas. */ | |
| 856 | |
| 857 static GTY(()) alias_set_type frame_set = -1; | |
| 858 | |
| 859 alias_set_type | |
| 860 get_frame_alias_set (void) | |
| 861 { | |
| 862 if (frame_set == -1) | |
| 863 frame_set = new_alias_set (); | |
| 864 | |
| 865 return frame_set; | |
| 866 } | |
| 867 | |
| 868 /* Inside SRC, the source of a SET, find a base address. */ | |
| 869 | |
| 870 static rtx | |
| 871 find_base_value (rtx src) | |
| 872 { | |
| 873 unsigned int regno; | |
| 874 | |
| 875 #if defined (FIND_BASE_TERM) | |
| 876 /* Try machine-dependent ways to find the base term. */ | |
| 877 src = FIND_BASE_TERM (src); | |
| 878 #endif | |
| 879 | |
| 880 switch (GET_CODE (src)) | |
| 881 { | |
| 882 case SYMBOL_REF: | |
| 883 case LABEL_REF: | |
| 884 return src; | |
| 885 | |
| 886 case REG: | |
| 887 regno = REGNO (src); | |
| 888 /* At the start of a function, argument registers have known base | |
| 889 values which may be lost later. Returning an ADDRESS | |
| 890 expression here allows optimization based on argument values | |
| 891 even when the argument registers are used for other purposes. */ | |
| 892 if (regno < FIRST_PSEUDO_REGISTER && copying_arguments) | |
| 893 return new_reg_base_value[regno]; | |
| 894 | |
| 895 /* If a pseudo has a known base value, return it. Do not do this | |
| 896 for non-fixed hard regs since it can result in a circular | |
| 897 dependency chain for registers which have values at function entry. | |
| 898 | |
| 899 The test above is not sufficient because the scheduler may move | |
| 900 a copy out of an arg reg past the NOTE_INSN_FUNCTION_BEGIN. */ | |
| 901 if ((regno >= FIRST_PSEUDO_REGISTER || fixed_regs[regno]) | |
| 902 && regno < VEC_length (rtx, reg_base_value)) | |
| 903 { | |
| 904 /* If we're inside init_alias_analysis, use new_reg_base_value | |
| 905 to reduce the number of relaxation iterations. */ | |
| 906 if (new_reg_base_value && new_reg_base_value[regno] | |
| 907 && DF_REG_DEF_COUNT (regno) == 1) | |
| 908 return new_reg_base_value[regno]; | |
| 909 | |
| 910 if (VEC_index (rtx, reg_base_value, regno)) | |
| 911 return VEC_index (rtx, reg_base_value, regno); | |
| 912 } | |
| 913 | |
| 914 return 0; | |
| 915 | |
| 916 case MEM: | |
| 917 /* Check for an argument passed in memory. Only record in the | |
| 918 copying-arguments block; it is too hard to track changes | |
| 919 otherwise. */ | |
| 920 if (copying_arguments | |
| 921 && (XEXP (src, 0) == arg_pointer_rtx | |
| 922 || (GET_CODE (XEXP (src, 0)) == PLUS | |
| 923 && XEXP (XEXP (src, 0), 0) == arg_pointer_rtx))) | |
| 924 return gen_rtx_ADDRESS (VOIDmode, src); | |
| 925 return 0; | |
| 926 | |
| 927 case CONST: | |
| 928 src = XEXP (src, 0); | |
| 929 if (GET_CODE (src) != PLUS && GET_CODE (src) != MINUS) | |
| 930 break; | |
| 931 | |
| 932 /* ... fall through ... */ | |
| 933 | |
| 934 case PLUS: | |
| 935 case MINUS: | |
| 936 { | |
| 937 rtx temp, src_0 = XEXP (src, 0), src_1 = XEXP (src, 1); | |
| 938 | |
| 939 /* If either operand is a REG that is a known pointer, then it | |
| 940 is the base. */ | |
| 941 if (REG_P (src_0) && REG_POINTER (src_0)) | |
| 942 return find_base_value (src_0); | |
| 943 if (REG_P (src_1) && REG_POINTER (src_1)) | |
| 944 return find_base_value (src_1); | |
| 945 | |
| 946 /* If either operand is a REG, then see if we already have | |
| 947 a known value for it. */ | |
| 948 if (REG_P (src_0)) | |
| 949 { | |
| 950 temp = find_base_value (src_0); | |
| 951 if (temp != 0) | |
| 952 src_0 = temp; | |
| 953 } | |
| 954 | |
| 955 if (REG_P (src_1)) | |
| 956 { | |
| 957 temp = find_base_value (src_1); | |
| 958 if (temp!= 0) | |
| 959 src_1 = temp; | |
| 960 } | |
| 961 | |
| 962 /* If either base is named object or a special address | |
| 963 (like an argument or stack reference), then use it for the | |
| 964 base term. */ | |
| 965 if (src_0 != 0 | |
| 966 && (GET_CODE (src_0) == SYMBOL_REF | |
| 967 || GET_CODE (src_0) == LABEL_REF | |
| 968 || (GET_CODE (src_0) == ADDRESS | |
| 969 && GET_MODE (src_0) != VOIDmode))) | |
| 970 return src_0; | |
| 971 | |
| 972 if (src_1 != 0 | |
| 973 && (GET_CODE (src_1) == SYMBOL_REF | |
| 974 || GET_CODE (src_1) == LABEL_REF | |
| 975 || (GET_CODE (src_1) == ADDRESS | |
| 976 && GET_MODE (src_1) != VOIDmode))) | |
| 977 return src_1; | |
| 978 | |
| 979 /* Guess which operand is the base address: | |
| 980 If either operand is a symbol, then it is the base. If | |
| 981 either operand is a CONST_INT, then the other is the base. */ | |
| 982 if (GET_CODE (src_1) == CONST_INT || CONSTANT_P (src_0)) | |
| 983 return find_base_value (src_0); | |
| 984 else if (GET_CODE (src_0) == CONST_INT || CONSTANT_P (src_1)) | |
| 985 return find_base_value (src_1); | |
| 986 | |
| 987 return 0; | |
| 988 } | |
| 989 | |
| 990 case LO_SUM: | |
| 991 /* The standard form is (lo_sum reg sym) so look only at the | |
| 992 second operand. */ | |
| 993 return find_base_value (XEXP (src, 1)); | |
| 994 | |
| 995 case AND: | |
| 996 /* If the second operand is constant set the base | |
| 997 address to the first operand. */ | |
| 998 if (GET_CODE (XEXP (src, 1)) == CONST_INT && INTVAL (XEXP (src, 1)) != 0) | |
| 999 return find_base_value (XEXP (src, 0)); | |
| 1000 return 0; | |
| 1001 | |
| 1002 case TRUNCATE: | |
| 1003 if (GET_MODE_SIZE (GET_MODE (src)) < GET_MODE_SIZE (Pmode)) | |
| 1004 break; | |
| 1005 /* Fall through. */ | |
| 1006 case HIGH: | |
| 1007 case PRE_INC: | |
| 1008 case PRE_DEC: | |
| 1009 case POST_INC: | |
| 1010 case POST_DEC: | |
| 1011 case PRE_MODIFY: | |
| 1012 case POST_MODIFY: | |
| 1013 return find_base_value (XEXP (src, 0)); | |
| 1014 | |
| 1015 case ZERO_EXTEND: | |
| 1016 case SIGN_EXTEND: /* used for NT/Alpha pointers */ | |
| 1017 { | |
| 1018 rtx temp = find_base_value (XEXP (src, 0)); | |
| 1019 | |
| 1020 if (temp != 0 && CONSTANT_P (temp)) | |
| 1021 temp = convert_memory_address (Pmode, temp); | |
| 1022 | |
| 1023 return temp; | |
| 1024 } | |
| 1025 | |
| 1026 default: | |
| 1027 break; | |
| 1028 } | |
| 1029 | |
| 1030 return 0; | |
| 1031 } | |
| 1032 | |
| 1033 /* Called from init_alias_analysis indirectly through note_stores. */ | |
| 1034 | |
| 1035 /* While scanning insns to find base values, reg_seen[N] is nonzero if | |
| 1036 register N has been set in this function. */ | |
| 1037 static char *reg_seen; | |
| 1038 | |
| 1039 /* Addresses which are known not to alias anything else are identified | |
| 1040 by a unique integer. */ | |
| 1041 static int unique_id; | |
| 1042 | |
| 1043 static void | |
| 1044 record_set (rtx dest, const_rtx set, void *data ATTRIBUTE_UNUSED) | |
| 1045 { | |
| 1046 unsigned regno; | |
| 1047 rtx src; | |
| 1048 int n; | |
| 1049 | |
| 1050 if (!REG_P (dest)) | |
| 1051 return; | |
| 1052 | |
| 1053 regno = REGNO (dest); | |
| 1054 | |
| 1055 gcc_assert (regno < VEC_length (rtx, reg_base_value)); | |
| 1056 | |
| 1057 /* If this spans multiple hard registers, then we must indicate that every | |
| 1058 register has an unusable value. */ | |
| 1059 if (regno < FIRST_PSEUDO_REGISTER) | |
| 1060 n = hard_regno_nregs[regno][GET_MODE (dest)]; | |
| 1061 else | |
| 1062 n = 1; | |
| 1063 if (n != 1) | |
| 1064 { | |
| 1065 while (--n >= 0) | |
| 1066 { | |
| 1067 reg_seen[regno + n] = 1; | |
| 1068 new_reg_base_value[regno + n] = 0; | |
| 1069 } | |
| 1070 return; | |
| 1071 } | |
| 1072 | |
| 1073 if (set) | |
| 1074 { | |
| 1075 /* A CLOBBER wipes out any old value but does not prevent a previously | |
| 1076 unset register from acquiring a base address (i.e. reg_seen is not | |
| 1077 set). */ | |
| 1078 if (GET_CODE (set) == CLOBBER) | |
| 1079 { | |
| 1080 new_reg_base_value[regno] = 0; | |
| 1081 return; | |
| 1082 } | |
| 1083 src = SET_SRC (set); | |
| 1084 } | |
| 1085 else | |
| 1086 { | |
| 1087 if (reg_seen[regno]) | |
| 1088 { | |
| 1089 new_reg_base_value[regno] = 0; | |
| 1090 return; | |
| 1091 } | |
| 1092 reg_seen[regno] = 1; | |
| 1093 new_reg_base_value[regno] = gen_rtx_ADDRESS (Pmode, | |
| 1094 GEN_INT (unique_id++)); | |
| 1095 return; | |
| 1096 } | |
| 1097 | |
| 1098 /* If this is not the first set of REGNO, see whether the new value | |
| 1099 is related to the old one. There are two cases of interest: | |
| 1100 | |
| 1101 (1) The register might be assigned an entirely new value | |
| 1102 that has the same base term as the original set. | |
| 1103 | |
| 1104 (2) The set might be a simple self-modification that | |
| 1105 cannot change REGNO's base value. | |
| 1106 | |
| 1107 If neither case holds, reject the original base value as invalid. | |
| 1108 Note that the following situation is not detected: | |
| 1109 | |
| 1110 extern int x, y; int *p = &x; p += (&y-&x); | |
| 1111 | |
| 1112 ANSI C does not allow computing the difference of addresses | |
| 1113 of distinct top level objects. */ | |
| 1114 if (new_reg_base_value[regno] != 0 | |
| 1115 && find_base_value (src) != new_reg_base_value[regno]) | |
| 1116 switch (GET_CODE (src)) | |
| 1117 { | |
| 1118 case LO_SUM: | |
| 1119 case MINUS: | |
| 1120 if (XEXP (src, 0) != dest && XEXP (src, 1) != dest) | |
| 1121 new_reg_base_value[regno] = 0; | |
| 1122 break; | |
| 1123 case PLUS: | |
| 1124 /* If the value we add in the PLUS is also a valid base value, | |
| 1125 this might be the actual base value, and the original value | |
| 1126 an index. */ | |
| 1127 { | |
| 1128 rtx other = NULL_RTX; | |
| 1129 | |
| 1130 if (XEXP (src, 0) == dest) | |
| 1131 other = XEXP (src, 1); | |
| 1132 else if (XEXP (src, 1) == dest) | |
| 1133 other = XEXP (src, 0); | |
| 1134 | |
| 1135 if (! other || find_base_value (other)) | |
| 1136 new_reg_base_value[regno] = 0; | |
| 1137 break; | |
| 1138 } | |
| 1139 case AND: | |
| 1140 if (XEXP (src, 0) != dest || GET_CODE (XEXP (src, 1)) != CONST_INT) | |
| 1141 new_reg_base_value[regno] = 0; | |
| 1142 break; | |
| 1143 default: | |
| 1144 new_reg_base_value[regno] = 0; | |
| 1145 break; | |
| 1146 } | |
| 1147 /* If this is the first set of a register, record the value. */ | |
| 1148 else if ((regno >= FIRST_PSEUDO_REGISTER || ! fixed_regs[regno]) | |
| 1149 && ! reg_seen[regno] && new_reg_base_value[regno] == 0) | |
| 1150 new_reg_base_value[regno] = find_base_value (src); | |
| 1151 | |
| 1152 reg_seen[regno] = 1; | |
| 1153 } | |
| 1154 | |
| 1155 /* If a value is known for REGNO, return it. */ | |
| 1156 | |
| 1157 rtx | |
| 1158 get_reg_known_value (unsigned int regno) | |
| 1159 { | |
| 1160 if (regno >= FIRST_PSEUDO_REGISTER) | |
| 1161 { | |
| 1162 regno -= FIRST_PSEUDO_REGISTER; | |
| 1163 if (regno < reg_known_value_size) | |
| 1164 return reg_known_value[regno]; | |
| 1165 } | |
| 1166 return NULL; | |
| 1167 } | |
| 1168 | |
| 1169 /* Set it. */ | |
| 1170 | |
| 1171 static void | |
| 1172 set_reg_known_value (unsigned int regno, rtx val) | |
| 1173 { | |
| 1174 if (regno >= FIRST_PSEUDO_REGISTER) | |
| 1175 { | |
| 1176 regno -= FIRST_PSEUDO_REGISTER; | |
| 1177 if (regno < reg_known_value_size) | |
| 1178 reg_known_value[regno] = val; | |
| 1179 } | |
| 1180 } | |
| 1181 | |
| 1182 /* Similarly for reg_known_equiv_p. */ | |
| 1183 | |
| 1184 bool | |
| 1185 get_reg_known_equiv_p (unsigned int regno) | |
| 1186 { | |
| 1187 if (regno >= FIRST_PSEUDO_REGISTER) | |
| 1188 { | |
| 1189 regno -= FIRST_PSEUDO_REGISTER; | |
| 1190 if (regno < reg_known_value_size) | |
| 1191 return reg_known_equiv_p[regno]; | |
| 1192 } | |
| 1193 return false; | |
| 1194 } | |
| 1195 | |
| 1196 static void | |
| 1197 set_reg_known_equiv_p (unsigned int regno, bool val) | |
| 1198 { | |
| 1199 if (regno >= FIRST_PSEUDO_REGISTER) | |
| 1200 { | |
| 1201 regno -= FIRST_PSEUDO_REGISTER; | |
| 1202 if (regno < reg_known_value_size) | |
| 1203 reg_known_equiv_p[regno] = val; | |
| 1204 } | |
| 1205 } | |
| 1206 | |
| 1207 | |
| 1208 /* Returns a canonical version of X, from the point of view alias | |
| 1209 analysis. (For example, if X is a MEM whose address is a register, | |
| 1210 and the register has a known value (say a SYMBOL_REF), then a MEM | |
| 1211 whose address is the SYMBOL_REF is returned.) */ | |
| 1212 | |
| 1213 rtx | |
| 1214 canon_rtx (rtx x) | |
| 1215 { | |
| 1216 /* Recursively look for equivalences. */ | |
| 1217 if (REG_P (x) && REGNO (x) >= FIRST_PSEUDO_REGISTER) | |
| 1218 { | |
| 1219 rtx t = get_reg_known_value (REGNO (x)); | |
| 1220 if (t == x) | |
| 1221 return x; | |
| 1222 if (t) | |
| 1223 return canon_rtx (t); | |
| 1224 } | |
| 1225 | |
| 1226 if (GET_CODE (x) == PLUS) | |
| 1227 { | |
| 1228 rtx x0 = canon_rtx (XEXP (x, 0)); | |
| 1229 rtx x1 = canon_rtx (XEXP (x, 1)); | |
| 1230 | |
| 1231 if (x0 != XEXP (x, 0) || x1 != XEXP (x, 1)) | |
| 1232 { | |
| 1233 if (GET_CODE (x0) == CONST_INT) | |
| 1234 return plus_constant (x1, INTVAL (x0)); | |
| 1235 else if (GET_CODE (x1) == CONST_INT) | |
| 1236 return plus_constant (x0, INTVAL (x1)); | |
| 1237 return gen_rtx_PLUS (GET_MODE (x), x0, x1); | |
| 1238 } | |
| 1239 } | |
| 1240 | |
| 1241 /* This gives us much better alias analysis when called from | |
| 1242 the loop optimizer. Note we want to leave the original | |
| 1243 MEM alone, but need to return the canonicalized MEM with | |
| 1244 all the flags with their original values. */ | |
| 1245 else if (MEM_P (x)) | |
| 1246 x = replace_equiv_address_nv (x, canon_rtx (XEXP (x, 0))); | |
| 1247 | |
| 1248 return x; | |
| 1249 } | |
| 1250 | |
| 1251 /* Return 1 if X and Y are identical-looking rtx's. | |
| 1252 Expect that X and Y has been already canonicalized. | |
| 1253 | |
| 1254 We use the data in reg_known_value above to see if two registers with | |
| 1255 different numbers are, in fact, equivalent. */ | |
| 1256 | |
| 1257 static int | |
| 1258 rtx_equal_for_memref_p (const_rtx x, const_rtx y) | |
| 1259 { | |
| 1260 int i; | |
| 1261 int j; | |
| 1262 enum rtx_code code; | |
| 1263 const char *fmt; | |
| 1264 | |
| 1265 if (x == 0 && y == 0) | |
| 1266 return 1; | |
| 1267 if (x == 0 || y == 0) | |
| 1268 return 0; | |
| 1269 | |
| 1270 if (x == y) | |
| 1271 return 1; | |
| 1272 | |
| 1273 code = GET_CODE (x); | |
| 1274 /* Rtx's of different codes cannot be equal. */ | |
| 1275 if (code != GET_CODE (y)) | |
| 1276 return 0; | |
| 1277 | |
| 1278 /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent. | |
| 1279 (REG:SI x) and (REG:HI x) are NOT equivalent. */ | |
| 1280 | |
| 1281 if (GET_MODE (x) != GET_MODE (y)) | |
| 1282 return 0; | |
| 1283 | |
| 1284 /* Some RTL can be compared without a recursive examination. */ | |
| 1285 switch (code) | |
| 1286 { | |
| 1287 case REG: | |
| 1288 return REGNO (x) == REGNO (y); | |
| 1289 | |
| 1290 case LABEL_REF: | |
| 1291 return XEXP (x, 0) == XEXP (y, 0); | |
| 1292 | |
| 1293 case SYMBOL_REF: | |
| 1294 return XSTR (x, 0) == XSTR (y, 0); | |
| 1295 | |
| 1296 case VALUE: | |
| 1297 case CONST_INT: | |
| 1298 case CONST_DOUBLE: | |
| 1299 case CONST_FIXED: | |
| 1300 /* There's no need to compare the contents of CONST_DOUBLEs or | |
| 1301 CONST_INTs because pointer equality is a good enough | |
| 1302 comparison for these nodes. */ | |
| 1303 return 0; | |
| 1304 | |
| 1305 default: | |
| 1306 break; | |
| 1307 } | |
| 1308 | |
| 1309 /* canon_rtx knows how to handle plus. No need to canonicalize. */ | |
| 1310 if (code == PLUS) | |
| 1311 return ((rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 0)) | |
| 1312 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 1))) | |
| 1313 || (rtx_equal_for_memref_p (XEXP (x, 0), XEXP (y, 1)) | |
| 1314 && rtx_equal_for_memref_p (XEXP (x, 1), XEXP (y, 0)))); | |
| 1315 /* For commutative operations, the RTX match if the operand match in any | |
| 1316 order. Also handle the simple binary and unary cases without a loop. */ | |
| 1317 if (COMMUTATIVE_P (x)) | |
| 1318 { | |
| 1319 rtx xop0 = canon_rtx (XEXP (x, 0)); | |
| 1320 rtx yop0 = canon_rtx (XEXP (y, 0)); | |
| 1321 rtx yop1 = canon_rtx (XEXP (y, 1)); | |
| 1322 | |
| 1323 return ((rtx_equal_for_memref_p (xop0, yop0) | |
| 1324 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), yop1)) | |
| 1325 || (rtx_equal_for_memref_p (xop0, yop1) | |
| 1326 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), yop0))); | |
| 1327 } | |
| 1328 else if (NON_COMMUTATIVE_P (x)) | |
| 1329 { | |
| 1330 return (rtx_equal_for_memref_p (canon_rtx (XEXP (x, 0)), | |
| 1331 canon_rtx (XEXP (y, 0))) | |
| 1332 && rtx_equal_for_memref_p (canon_rtx (XEXP (x, 1)), | |
| 1333 canon_rtx (XEXP (y, 1)))); | |
| 1334 } | |
| 1335 else if (UNARY_P (x)) | |
| 1336 return rtx_equal_for_memref_p (canon_rtx (XEXP (x, 0)), | |
| 1337 canon_rtx (XEXP (y, 0))); | |
| 1338 | |
| 1339 /* Compare the elements. If any pair of corresponding elements | |
| 1340 fail to match, return 0 for the whole things. | |
| 1341 | |
| 1342 Limit cases to types which actually appear in addresses. */ | |
| 1343 | |
| 1344 fmt = GET_RTX_FORMAT (code); | |
| 1345 for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) | |
| 1346 { | |
| 1347 switch (fmt[i]) | |
| 1348 { | |
| 1349 case 'i': | |
| 1350 if (XINT (x, i) != XINT (y, i)) | |
| 1351 return 0; | |
| 1352 break; | |
| 1353 | |
| 1354 case 'E': | |
| 1355 /* Two vectors must have the same length. */ | |
| 1356 if (XVECLEN (x, i) != XVECLEN (y, i)) | |
| 1357 return 0; | |
| 1358 | |
| 1359 /* And the corresponding elements must match. */ | |
| 1360 for (j = 0; j < XVECLEN (x, i); j++) | |
| 1361 if (rtx_equal_for_memref_p (canon_rtx (XVECEXP (x, i, j)), | |
| 1362 canon_rtx (XVECEXP (y, i, j))) == 0) | |
| 1363 return 0; | |
| 1364 break; | |
| 1365 | |
| 1366 case 'e': | |
| 1367 if (rtx_equal_for_memref_p (canon_rtx (XEXP (x, i)), | |
| 1368 canon_rtx (XEXP (y, i))) == 0) | |
| 1369 return 0; | |
| 1370 break; | |
| 1371 | |
| 1372 /* This can happen for asm operands. */ | |
| 1373 case 's': | |
| 1374 if (strcmp (XSTR (x, i), XSTR (y, i))) | |
| 1375 return 0; | |
| 1376 break; | |
| 1377 | |
| 1378 /* This can happen for an asm which clobbers memory. */ | |
| 1379 case '0': | |
| 1380 break; | |
| 1381 | |
| 1382 /* It is believed that rtx's at this level will never | |
| 1383 contain anything but integers and other rtx's, | |
| 1384 except for within LABEL_REFs and SYMBOL_REFs. */ | |
| 1385 default: | |
| 1386 gcc_unreachable (); | |
| 1387 } | |
| 1388 } | |
| 1389 return 1; | |
| 1390 } | |
| 1391 | |
| 1392 rtx | |
| 1393 find_base_term (rtx x) | |
| 1394 { | |
| 1395 cselib_val *val; | |
| 1396 struct elt_loc_list *l; | |
| 1397 | |
| 1398 #if defined (FIND_BASE_TERM) | |
| 1399 /* Try machine-dependent ways to find the base term. */ | |
| 1400 x = FIND_BASE_TERM (x); | |
| 1401 #endif | |
| 1402 | |
| 1403 switch (GET_CODE (x)) | |
| 1404 { | |
| 1405 case REG: | |
| 1406 return REG_BASE_VALUE (x); | |
| 1407 | |
| 1408 case TRUNCATE: | |
| 1409 if (GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (Pmode)) | |
| 1410 return 0; | |
| 1411 /* Fall through. */ | |
| 1412 case HIGH: | |
| 1413 case PRE_INC: | |
| 1414 case PRE_DEC: | |
| 1415 case POST_INC: | |
| 1416 case POST_DEC: | |
| 1417 case PRE_MODIFY: | |
| 1418 case POST_MODIFY: | |
| 1419 return find_base_term (XEXP (x, 0)); | |
| 1420 | |
| 1421 case ZERO_EXTEND: | |
| 1422 case SIGN_EXTEND: /* Used for Alpha/NT pointers */ | |
| 1423 { | |
| 1424 rtx temp = find_base_term (XEXP (x, 0)); | |
| 1425 | |
| 1426 if (temp != 0 && CONSTANT_P (temp)) | |
| 1427 temp = convert_memory_address (Pmode, temp); | |
| 1428 | |
| 1429 return temp; | |
| 1430 } | |
| 1431 | |
| 1432 case VALUE: | |
| 1433 val = CSELIB_VAL_PTR (x); | |
| 1434 if (!val) | |
| 1435 return 0; | |
| 1436 for (l = val->locs; l; l = l->next) | |
| 1437 if ((x = find_base_term (l->loc)) != 0) | |
| 1438 return x; | |
| 1439 return 0; | |
| 1440 | |
|
19
58ad6c70ea60
update gcc from 4.4.0 to 4.4.1.
kent@firefly.cr.ie.u-ryukyu.ac.jp
parents:
0
diff
changeset
|
1441 case LO_SUM: |
|
58ad6c70ea60
update gcc from 4.4.0 to 4.4.1.
kent@firefly.cr.ie.u-ryukyu.ac.jp
parents:
0
diff
changeset
|
1442 /* The standard form is (lo_sum reg sym) so look only at the |
|
58ad6c70ea60
update gcc from 4.4.0 to 4.4.1.
kent@firefly.cr.ie.u-ryukyu.ac.jp
parents:
0
diff
changeset
|
1443 second operand. */ |
|
58ad6c70ea60
update gcc from 4.4.0 to 4.4.1.
kent@firefly.cr.ie.u-ryukyu.ac.jp
parents:
0
diff
changeset
|
1444 return find_base_term (XEXP (x, 1)); |
|
58ad6c70ea60
update gcc from 4.4.0 to 4.4.1.
kent@firefly.cr.ie.u-ryukyu.ac.jp
parents:
0
diff
changeset
|
1445 |
| 0 | 1446 case CONST: |
| 1447 x = XEXP (x, 0); | |
| 1448 if (GET_CODE (x) != PLUS && GET_CODE (x) != MINUS) | |
| 1449 return 0; | |
| 1450 /* Fall through. */ | |
| 1451 case PLUS: | |
| 1452 case MINUS: | |
| 1453 { | |
| 1454 rtx tmp1 = XEXP (x, 0); | |
| 1455 rtx tmp2 = XEXP (x, 1); | |
| 1456 | |
| 1457 /* This is a little bit tricky since we have to determine which of | |
| 1458 the two operands represents the real base address. Otherwise this | |
| 1459 routine may return the index register instead of the base register. | |
| 1460 | |
| 1461 That may cause us to believe no aliasing was possible, when in | |
| 1462 fact aliasing is possible. | |
| 1463 | |
| 1464 We use a few simple tests to guess the base register. Additional | |
| 1465 tests can certainly be added. For example, if one of the operands | |
| 1466 is a shift or multiply, then it must be the index register and the | |
| 1467 other operand is the base register. */ | |
| 1468 | |
| 1469 if (tmp1 == pic_offset_table_rtx && CONSTANT_P (tmp2)) | |
| 1470 return find_base_term (tmp2); | |
| 1471 | |
| 1472 /* If either operand is known to be a pointer, then use it | |
| 1473 to determine the base term. */ | |
| 1474 if (REG_P (tmp1) && REG_POINTER (tmp1)) | |
| 1475 return find_base_term (tmp1); | |
| 1476 | |
| 1477 if (REG_P (tmp2) && REG_POINTER (tmp2)) | |
| 1478 return find_base_term (tmp2); | |
| 1479 | |
| 1480 /* Neither operand was known to be a pointer. Go ahead and find the | |
| 1481 base term for both operands. */ | |
| 1482 tmp1 = find_base_term (tmp1); | |
| 1483 tmp2 = find_base_term (tmp2); | |
| 1484 | |
| 1485 /* If either base term is named object or a special address | |
| 1486 (like an argument or stack reference), then use it for the | |
| 1487 base term. */ | |
| 1488 if (tmp1 != 0 | |
| 1489 && (GET_CODE (tmp1) == SYMBOL_REF | |
| 1490 || GET_CODE (tmp1) == LABEL_REF | |
| 1491 || (GET_CODE (tmp1) == ADDRESS | |
| 1492 && GET_MODE (tmp1) != VOIDmode))) | |
| 1493 return tmp1; | |
| 1494 | |
| 1495 if (tmp2 != 0 | |
| 1496 && (GET_CODE (tmp2) == SYMBOL_REF | |
| 1497 || GET_CODE (tmp2) == LABEL_REF | |
| 1498 || (GET_CODE (tmp2) == ADDRESS | |
| 1499 && GET_MODE (tmp2) != VOIDmode))) | |
| 1500 return tmp2; | |
| 1501 | |
| 1502 /* We could not determine which of the two operands was the | |
| 1503 base register and which was the index. So we can determine | |
| 1504 nothing from the base alias check. */ | |
| 1505 return 0; | |
| 1506 } | |
| 1507 | |
| 1508 case AND: | |
| 1509 if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) != 0) | |
| 1510 return find_base_term (XEXP (x, 0)); | |
| 1511 return 0; | |
| 1512 | |
| 1513 case SYMBOL_REF: | |
| 1514 case LABEL_REF: | |
| 1515 return x; | |
| 1516 | |
| 1517 default: | |
| 1518 return 0; | |
| 1519 } | |
| 1520 } | |
| 1521 | |
| 1522 /* Return 0 if the addresses X and Y are known to point to different | |
| 1523 objects, 1 if they might be pointers to the same object. */ | |
| 1524 | |
| 1525 static int | |
| 1526 base_alias_check (rtx x, rtx y, enum machine_mode x_mode, | |
| 1527 enum machine_mode y_mode) | |
| 1528 { | |
| 1529 rtx x_base = find_base_term (x); | |
| 1530 rtx y_base = find_base_term (y); | |
| 1531 | |
| 1532 /* If the address itself has no known base see if a known equivalent | |
| 1533 value has one. If either address still has no known base, nothing | |
| 1534 is known about aliasing. */ | |
| 1535 if (x_base == 0) | |
| 1536 { | |
| 1537 rtx x_c; | |
| 1538 | |
| 1539 if (! flag_expensive_optimizations || (x_c = canon_rtx (x)) == x) | |
| 1540 return 1; | |
| 1541 | |
| 1542 x_base = find_base_term (x_c); | |
| 1543 if (x_base == 0) | |
| 1544 return 1; | |
| 1545 } | |
| 1546 | |
| 1547 if (y_base == 0) | |
| 1548 { | |
| 1549 rtx y_c; | |
| 1550 if (! flag_expensive_optimizations || (y_c = canon_rtx (y)) == y) | |
| 1551 return 1; | |
| 1552 | |
| 1553 y_base = find_base_term (y_c); | |
| 1554 if (y_base == 0) | |
| 1555 return 1; | |
| 1556 } | |
| 1557 | |
| 1558 /* If the base addresses are equal nothing is known about aliasing. */ | |
| 1559 if (rtx_equal_p (x_base, y_base)) | |
| 1560 return 1; | |
| 1561 | |
| 1562 /* The base addresses are different expressions. If they are not accessed | |
| 1563 via AND, there is no conflict. We can bring knowledge of object | |
| 1564 alignment into play here. For example, on alpha, "char a, b;" can | |
| 1565 alias one another, though "char a; long b;" cannot. AND addesses may | |
| 1566 implicitly alias surrounding objects; i.e. unaligned access in DImode | |
| 1567 via AND address can alias all surrounding object types except those | |
| 1568 with aligment 8 or higher. */ | |
| 1569 if (GET_CODE (x) == AND && GET_CODE (y) == AND) | |
| 1570 return 1; | |
| 1571 if (GET_CODE (x) == AND | |
| 1572 && (GET_CODE (XEXP (x, 1)) != CONST_INT | |
| 1573 || (int) GET_MODE_UNIT_SIZE (y_mode) < -INTVAL (XEXP (x, 1)))) | |
| 1574 return 1; | |
| 1575 if (GET_CODE (y) == AND | |
| 1576 && (GET_CODE (XEXP (y, 1)) != CONST_INT | |
| 1577 || (int) GET_MODE_UNIT_SIZE (x_mode) < -INTVAL (XEXP (y, 1)))) | |
| 1578 return 1; | |
| 1579 | |
| 1580 /* Differing symbols not accessed via AND never alias. */ | |
| 1581 if (GET_CODE (x_base) != ADDRESS && GET_CODE (y_base) != ADDRESS) | |
| 1582 return 0; | |
| 1583 | |
| 1584 /* If one address is a stack reference there can be no alias: | |
| 1585 stack references using different base registers do not alias, | |
| 1586 a stack reference can not alias a parameter, and a stack reference | |
| 1587 can not alias a global. */ | |
| 1588 if ((GET_CODE (x_base) == ADDRESS && GET_MODE (x_base) == Pmode) | |
| 1589 || (GET_CODE (y_base) == ADDRESS && GET_MODE (y_base) == Pmode)) | |
| 1590 return 0; | |
| 1591 | |
| 1592 if (! flag_argument_noalias) | |
| 1593 return 1; | |
| 1594 | |
| 1595 if (flag_argument_noalias > 1) | |
| 1596 return 0; | |
| 1597 | |
| 1598 /* Weak noalias assertion (arguments are distinct, but may match globals). */ | |
| 1599 return ! (GET_MODE (x_base) == VOIDmode && GET_MODE (y_base) == VOIDmode); | |
| 1600 } | |
| 1601 | |
| 1602 /* Convert the address X into something we can use. This is done by returning | |
| 1603 it unchanged unless it is a value; in the latter case we call cselib to get | |
| 1604 a more useful rtx. */ | |
| 1605 | |
| 1606 rtx | |
| 1607 get_addr (rtx x) | |
| 1608 { | |
| 1609 cselib_val *v; | |
| 1610 struct elt_loc_list *l; | |
| 1611 | |
| 1612 if (GET_CODE (x) != VALUE) | |
| 1613 return x; | |
| 1614 v = CSELIB_VAL_PTR (x); | |
| 1615 if (v) | |
| 1616 { | |
| 1617 for (l = v->locs; l; l = l->next) | |
| 1618 if (CONSTANT_P (l->loc)) | |
| 1619 return l->loc; | |
| 1620 for (l = v->locs; l; l = l->next) | |
| 1621 if (!REG_P (l->loc) && !MEM_P (l->loc)) | |
| 1622 return l->loc; | |
| 1623 if (v->locs) | |
| 1624 return v->locs->loc; | |
| 1625 } | |
| 1626 return x; | |
| 1627 } | |
| 1628 | |
| 1629 /* Return the address of the (N_REFS + 1)th memory reference to ADDR | |
| 1630 where SIZE is the size in bytes of the memory reference. If ADDR | |
| 1631 is not modified by the memory reference then ADDR is returned. */ | |
| 1632 | |
| 1633 static rtx | |
| 1634 addr_side_effect_eval (rtx addr, int size, int n_refs) | |
| 1635 { | |
| 1636 int offset = 0; | |
| 1637 | |
| 1638 switch (GET_CODE (addr)) | |
| 1639 { | |
| 1640 case PRE_INC: | |
| 1641 offset = (n_refs + 1) * size; | |
| 1642 break; | |
| 1643 case PRE_DEC: | |
| 1644 offset = -(n_refs + 1) * size; | |
| 1645 break; | |
| 1646 case POST_INC: | |
| 1647 offset = n_refs * size; | |
| 1648 break; | |
| 1649 case POST_DEC: | |
| 1650 offset = -n_refs * size; | |
| 1651 break; | |
| 1652 | |
| 1653 default: | |
| 1654 return addr; | |
| 1655 } | |
| 1656 | |
| 1657 if (offset) | |
| 1658 addr = gen_rtx_PLUS (GET_MODE (addr), XEXP (addr, 0), | |
| 1659 GEN_INT (offset)); | |
| 1660 else | |
| 1661 addr = XEXP (addr, 0); | |
| 1662 addr = canon_rtx (addr); | |
| 1663 | |
| 1664 return addr; | |
| 1665 } | |
| 1666 | |
| 1667 /* Return nonzero if X and Y (memory addresses) could reference the | |
| 1668 same location in memory. C is an offset accumulator. When | |
| 1669 C is nonzero, we are testing aliases between X and Y + C. | |
| 1670 XSIZE is the size in bytes of the X reference, | |
| 1671 similarly YSIZE is the size in bytes for Y. | |
| 1672 Expect that canon_rtx has been already called for X and Y. | |
| 1673 | |
| 1674 If XSIZE or YSIZE is zero, we do not know the amount of memory being | |
| 1675 referenced (the reference was BLKmode), so make the most pessimistic | |
| 1676 assumptions. | |
| 1677 | |
| 1678 If XSIZE or YSIZE is negative, we may access memory outside the object | |
| 1679 being referenced as a side effect. This can happen when using AND to | |
| 1680 align memory references, as is done on the Alpha. | |
| 1681 | |
| 1682 Nice to notice that varying addresses cannot conflict with fp if no | |
| 1683 local variables had their addresses taken, but that's too hard now. */ | |
| 1684 | |
| 1685 static int | |
| 1686 memrefs_conflict_p (int xsize, rtx x, int ysize, rtx y, HOST_WIDE_INT c) | |
| 1687 { | |
| 1688 if (GET_CODE (x) == VALUE) | |
| 1689 x = get_addr (x); | |
| 1690 if (GET_CODE (y) == VALUE) | |
| 1691 y = get_addr (y); | |
| 1692 if (GET_CODE (x) == HIGH) | |
| 1693 x = XEXP (x, 0); | |
| 1694 else if (GET_CODE (x) == LO_SUM) | |
| 1695 x = XEXP (x, 1); | |
| 1696 else | |
| 1697 x = addr_side_effect_eval (x, xsize, 0); | |
| 1698 if (GET_CODE (y) == HIGH) | |
| 1699 y = XEXP (y, 0); | |
| 1700 else if (GET_CODE (y) == LO_SUM) | |
| 1701 y = XEXP (y, 1); | |
| 1702 else | |
| 1703 y = addr_side_effect_eval (y, ysize, 0); | |
| 1704 | |
| 1705 if (rtx_equal_for_memref_p (x, y)) | |
| 1706 { | |
| 1707 if (xsize <= 0 || ysize <= 0) | |
| 1708 return 1; | |
| 1709 if (c >= 0 && xsize > c) | |
| 1710 return 1; | |
| 1711 if (c < 0 && ysize+c > 0) | |
| 1712 return 1; | |
| 1713 return 0; | |
| 1714 } | |
| 1715 | |
| 1716 /* This code used to check for conflicts involving stack references and | |
| 1717 globals but the base address alias code now handles these cases. */ | |
| 1718 | |
| 1719 if (GET_CODE (x) == PLUS) | |
| 1720 { | |
| 1721 /* The fact that X is canonicalized means that this | |
| 1722 PLUS rtx is canonicalized. */ | |
| 1723 rtx x0 = XEXP (x, 0); | |
| 1724 rtx x1 = XEXP (x, 1); | |
| 1725 | |
| 1726 if (GET_CODE (y) == PLUS) | |
| 1727 { | |
| 1728 /* The fact that Y is canonicalized means that this | |
| 1729 PLUS rtx is canonicalized. */ | |
| 1730 rtx y0 = XEXP (y, 0); | |
| 1731 rtx y1 = XEXP (y, 1); | |
| 1732 | |
| 1733 if (rtx_equal_for_memref_p (x1, y1)) | |
| 1734 return memrefs_conflict_p (xsize, x0, ysize, y0, c); | |
| 1735 if (rtx_equal_for_memref_p (x0, y0)) | |
| 1736 return memrefs_conflict_p (xsize, x1, ysize, y1, c); | |
| 1737 if (GET_CODE (x1) == CONST_INT) | |
| 1738 { | |
| 1739 if (GET_CODE (y1) == CONST_INT) | |
| 1740 return memrefs_conflict_p (xsize, x0, ysize, y0, | |
| 1741 c - INTVAL (x1) + INTVAL (y1)); | |
| 1742 else | |
| 1743 return memrefs_conflict_p (xsize, x0, ysize, y, | |
| 1744 c - INTVAL (x1)); | |
| 1745 } | |
| 1746 else if (GET_CODE (y1) == CONST_INT) | |
| 1747 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1)); | |
| 1748 | |
| 1749 return 1; | |
| 1750 } | |
| 1751 else if (GET_CODE (x1) == CONST_INT) | |
| 1752 return memrefs_conflict_p (xsize, x0, ysize, y, c - INTVAL (x1)); | |
| 1753 } | |
| 1754 else if (GET_CODE (y) == PLUS) | |
| 1755 { | |
| 1756 /* The fact that Y is canonicalized means that this | |
| 1757 PLUS rtx is canonicalized. */ | |
| 1758 rtx y0 = XEXP (y, 0); | |
| 1759 rtx y1 = XEXP (y, 1); | |
| 1760 | |
| 1761 if (GET_CODE (y1) == CONST_INT) | |
| 1762 return memrefs_conflict_p (xsize, x, ysize, y0, c + INTVAL (y1)); | |
| 1763 else | |
| 1764 return 1; | |
| 1765 } | |
| 1766 | |
| 1767 if (GET_CODE (x) == GET_CODE (y)) | |
| 1768 switch (GET_CODE (x)) | |
| 1769 { | |
| 1770 case MULT: | |
| 1771 { | |
| 1772 /* Handle cases where we expect the second operands to be the | |
| 1773 same, and check only whether the first operand would conflict | |
| 1774 or not. */ | |
| 1775 rtx x0, y0; | |
| 1776 rtx x1 = canon_rtx (XEXP (x, 1)); | |
| 1777 rtx y1 = canon_rtx (XEXP (y, 1)); | |
| 1778 if (! rtx_equal_for_memref_p (x1, y1)) | |
| 1779 return 1; | |
| 1780 x0 = canon_rtx (XEXP (x, 0)); | |
| 1781 y0 = canon_rtx (XEXP (y, 0)); | |
| 1782 if (rtx_equal_for_memref_p (x0, y0)) | |
| 1783 return (xsize == 0 || ysize == 0 | |
| 1784 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0)); | |
| 1785 | |
| 1786 /* Can't properly adjust our sizes. */ | |
| 1787 if (GET_CODE (x1) != CONST_INT) | |
| 1788 return 1; | |
| 1789 xsize /= INTVAL (x1); | |
| 1790 ysize /= INTVAL (x1); | |
| 1791 c /= INTVAL (x1); | |
| 1792 return memrefs_conflict_p (xsize, x0, ysize, y0, c); | |
| 1793 } | |
| 1794 | |
| 1795 default: | |
| 1796 break; | |
| 1797 } | |
| 1798 | |
| 1799 /* Treat an access through an AND (e.g. a subword access on an Alpha) | |
| 1800 as an access with indeterminate size. Assume that references | |
| 1801 besides AND are aligned, so if the size of the other reference is | |
| 1802 at least as large as the alignment, assume no other overlap. */ | |
| 1803 if (GET_CODE (x) == AND && GET_CODE (XEXP (x, 1)) == CONST_INT) | |
| 1804 { | |
| 1805 if (GET_CODE (y) == AND || ysize < -INTVAL (XEXP (x, 1))) | |
| 1806 xsize = -1; | |
| 1807 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), ysize, y, c); | |
| 1808 } | |
| 1809 if (GET_CODE (y) == AND && GET_CODE (XEXP (y, 1)) == CONST_INT) | |
| 1810 { | |
| 1811 /* ??? If we are indexing far enough into the array/structure, we | |
| 1812 may yet be able to determine that we can not overlap. But we | |
| 1813 also need to that we are far enough from the end not to overlap | |
| 1814 a following reference, so we do nothing with that for now. */ | |
| 1815 if (GET_CODE (x) == AND || xsize < -INTVAL (XEXP (y, 1))) | |
| 1816 ysize = -1; | |
| 1817 return memrefs_conflict_p (xsize, x, ysize, canon_rtx (XEXP (y, 0)), c); | |
| 1818 } | |
| 1819 | |
| 1820 if (CONSTANT_P (x)) | |
| 1821 { | |
| 1822 if (GET_CODE (x) == CONST_INT && GET_CODE (y) == CONST_INT) | |
| 1823 { | |
| 1824 c += (INTVAL (y) - INTVAL (x)); | |
| 1825 return (xsize <= 0 || ysize <= 0 | |
| 1826 || (c >= 0 && xsize > c) || (c < 0 && ysize+c > 0)); | |
| 1827 } | |
| 1828 | |
| 1829 if (GET_CODE (x) == CONST) | |
| 1830 { | |
| 1831 if (GET_CODE (y) == CONST) | |
| 1832 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), | |
| 1833 ysize, canon_rtx (XEXP (y, 0)), c); | |
| 1834 else | |
| 1835 return memrefs_conflict_p (xsize, canon_rtx (XEXP (x, 0)), | |
| 1836 ysize, y, c); | |
| 1837 } | |
| 1838 if (GET_CODE (y) == CONST) | |
| 1839 return memrefs_conflict_p (xsize, x, ysize, | |
| 1840 canon_rtx (XEXP (y, 0)), c); | |
| 1841 | |
| 1842 if (CONSTANT_P (y)) | |
| 1843 return (xsize <= 0 || ysize <= 0 | |
| 1844 || (rtx_equal_for_memref_p (x, y) | |
| 1845 && ((c >= 0 && xsize > c) || (c < 0 && ysize+c > 0)))); | |
| 1846 | |
| 1847 return 1; | |
| 1848 } | |
| 1849 return 1; | |
| 1850 } | |
| 1851 | |
| 1852 /* Functions to compute memory dependencies. | |
| 1853 | |
| 1854 Since we process the insns in execution order, we can build tables | |
| 1855 to keep track of what registers are fixed (and not aliased), what registers | |
| 1856 are varying in known ways, and what registers are varying in unknown | |
| 1857 ways. | |
| 1858 | |
| 1859 If both memory references are volatile, then there must always be a | |
| 1860 dependence between the two references, since their order can not be | |
| 1861 changed. A volatile and non-volatile reference can be interchanged | |
| 1862 though. | |
| 1863 | |
| 1864 A MEM_IN_STRUCT reference at a non-AND varying address can never | |
| 1865 conflict with a non-MEM_IN_STRUCT reference at a fixed address. We | |
| 1866 also must allow AND addresses, because they may generate accesses | |
| 1867 outside the object being referenced. This is used to generate | |
| 1868 aligned addresses from unaligned addresses, for instance, the alpha | |
| 1869 storeqi_unaligned pattern. */ | |
| 1870 | |
| 1871 /* Read dependence: X is read after read in MEM takes place. There can | |
| 1872 only be a dependence here if both reads are volatile. */ | |
| 1873 | |
| 1874 int | |
| 1875 read_dependence (const_rtx mem, const_rtx x) | |
| 1876 { | |
| 1877 return MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem); | |
| 1878 } | |
| 1879 | |
| 1880 /* Returns MEM1 if and only if MEM1 is a scalar at a fixed address and | |
| 1881 MEM2 is a reference to a structure at a varying address, or returns | |
| 1882 MEM2 if vice versa. Otherwise, returns NULL_RTX. If a non-NULL | |
| 1883 value is returned MEM1 and MEM2 can never alias. VARIES_P is used | |
| 1884 to decide whether or not an address may vary; it should return | |
| 1885 nonzero whenever variation is possible. | |
| 1886 MEM1_ADDR and MEM2_ADDR are the addresses of MEM1 and MEM2. */ | |
| 1887 | |
| 1888 static const_rtx | |
| 1889 fixed_scalar_and_varying_struct_p (const_rtx mem1, const_rtx mem2, rtx mem1_addr, | |
| 1890 rtx mem2_addr, | |
| 1891 bool (*varies_p) (const_rtx, bool)) | |
| 1892 { | |
| 1893 if (! flag_strict_aliasing) | |
| 1894 return NULL_RTX; | |
| 1895 | |
| 1896 if (MEM_ALIAS_SET (mem2) | |
| 1897 && MEM_SCALAR_P (mem1) && MEM_IN_STRUCT_P (mem2) | |
| 1898 && !varies_p (mem1_addr, 1) && varies_p (mem2_addr, 1)) | |
| 1899 /* MEM1 is a scalar at a fixed address; MEM2 is a struct at a | |
| 1900 varying address. */ | |
| 1901 return mem1; | |
| 1902 | |
| 1903 if (MEM_ALIAS_SET (mem1) | |
| 1904 && MEM_IN_STRUCT_P (mem1) && MEM_SCALAR_P (mem2) | |
| 1905 && varies_p (mem1_addr, 1) && !varies_p (mem2_addr, 1)) | |
| 1906 /* MEM2 is a scalar at a fixed address; MEM1 is a struct at a | |
| 1907 varying address. */ | |
| 1908 return mem2; | |
| 1909 | |
| 1910 return NULL_RTX; | |
| 1911 } | |
| 1912 | |
| 1913 /* Returns nonzero if something about the mode or address format MEM1 | |
| 1914 indicates that it might well alias *anything*. */ | |
| 1915 | |
| 1916 static int | |
| 1917 aliases_everything_p (const_rtx mem) | |
| 1918 { | |
| 1919 if (GET_CODE (XEXP (mem, 0)) == AND) | |
| 1920 /* If the address is an AND, it's very hard to know at what it is | |
| 1921 actually pointing. */ | |
| 1922 return 1; | |
| 1923 | |
| 1924 return 0; | |
| 1925 } | |
| 1926 | |
| 1927 /* Return true if we can determine that the fields referenced cannot | |
| 1928 overlap for any pair of objects. */ | |
| 1929 | |
| 1930 static bool | |
| 1931 nonoverlapping_component_refs_p (const_tree x, const_tree y) | |
| 1932 { | |
| 1933 const_tree fieldx, fieldy, typex, typey, orig_y; | |
| 1934 | |
| 1935 do | |
| 1936 { | |
| 1937 /* The comparison has to be done at a common type, since we don't | |
| 1938 know how the inheritance hierarchy works. */ | |
| 1939 orig_y = y; | |
| 1940 do | |
| 1941 { | |
| 1942 fieldx = TREE_OPERAND (x, 1); | |
| 1943 typex = TYPE_MAIN_VARIANT (DECL_FIELD_CONTEXT (fieldx)); | |
| 1944 | |
| 1945 y = orig_y; | |
| 1946 do | |
| 1947 { | |
| 1948 fieldy = TREE_OPERAND (y, 1); | |
| 1949 typey = TYPE_MAIN_VARIANT (DECL_FIELD_CONTEXT (fieldy)); | |
| 1950 | |
| 1951 if (typex == typey) | |
| 1952 goto found; | |
| 1953 | |
| 1954 y = TREE_OPERAND (y, 0); | |
| 1955 } | |
| 1956 while (y && TREE_CODE (y) == COMPONENT_REF); | |
| 1957 | |
| 1958 x = TREE_OPERAND (x, 0); | |
| 1959 } | |
| 1960 while (x && TREE_CODE (x) == COMPONENT_REF); | |
| 1961 /* Never found a common type. */ | |
| 1962 return false; | |
| 1963 | |
| 1964 found: | |
| 1965 /* If we're left with accessing different fields of a structure, | |
| 1966 then no overlap. */ | |
| 1967 if (TREE_CODE (typex) == RECORD_TYPE | |
| 1968 && fieldx != fieldy) | |
| 1969 return true; | |
| 1970 | |
| 1971 /* The comparison on the current field failed. If we're accessing | |
| 1972 a very nested structure, look at the next outer level. */ | |
| 1973 x = TREE_OPERAND (x, 0); | |
| 1974 y = TREE_OPERAND (y, 0); | |
| 1975 } | |
| 1976 while (x && y | |
| 1977 && TREE_CODE (x) == COMPONENT_REF | |
| 1978 && TREE_CODE (y) == COMPONENT_REF); | |
| 1979 | |
| 1980 return false; | |
| 1981 } | |
| 1982 | |
| 1983 /* Look at the bottom of the COMPONENT_REF list for a DECL, and return it. */ | |
| 1984 | |
| 1985 static tree | |
| 1986 decl_for_component_ref (tree x) | |
| 1987 { | |
| 1988 do | |
| 1989 { | |
| 1990 x = TREE_OPERAND (x, 0); | |
| 1991 } | |
| 1992 while (x && TREE_CODE (x) == COMPONENT_REF); | |
| 1993 | |
| 1994 return x && DECL_P (x) ? x : NULL_TREE; | |
| 1995 } | |
| 1996 | |
| 1997 /* Walk up the COMPONENT_REF list and adjust OFFSET to compensate for the | |
| 1998 offset of the field reference. */ | |
| 1999 | |
| 2000 static rtx | |
| 2001 adjust_offset_for_component_ref (tree x, rtx offset) | |
| 2002 { | |
| 2003 HOST_WIDE_INT ioffset; | |
| 2004 | |
| 2005 if (! offset) | |
| 2006 return NULL_RTX; | |
| 2007 | |
| 2008 ioffset = INTVAL (offset); | |
| 2009 do | |
| 2010 { | |
| 2011 tree offset = component_ref_field_offset (x); | |
| 2012 tree field = TREE_OPERAND (x, 1); | |
| 2013 | |
| 2014 if (! host_integerp (offset, 1)) | |
| 2015 return NULL_RTX; | |
| 2016 ioffset += (tree_low_cst (offset, 1) | |
| 2017 + (tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 1) | |
| 2018 / BITS_PER_UNIT)); | |
| 2019 | |
| 2020 x = TREE_OPERAND (x, 0); | |
| 2021 } | |
| 2022 while (x && TREE_CODE (x) == COMPONENT_REF); | |
| 2023 | |
| 2024 return GEN_INT (ioffset); | |
| 2025 } | |
| 2026 | |
| 2027 /* Return nonzero if we can determine the exprs corresponding to memrefs | |
| 2028 X and Y and they do not overlap. */ | |
| 2029 | |
| 2030 int | |
| 2031 nonoverlapping_memrefs_p (const_rtx x, const_rtx y) | |
| 2032 { | |
| 2033 tree exprx = MEM_EXPR (x), expry = MEM_EXPR (y); | |
| 2034 rtx rtlx, rtly; | |
| 2035 rtx basex, basey; | |
| 2036 rtx moffsetx, moffsety; | |
| 2037 HOST_WIDE_INT offsetx = 0, offsety = 0, sizex, sizey, tem; | |
| 2038 | |
| 2039 /* Unless both have exprs, we can't tell anything. */ | |
| 2040 if (exprx == 0 || expry == 0) | |
| 2041 return 0; | |
| 2042 | |
| 2043 /* If both are field references, we may be able to determine something. */ | |
| 2044 if (TREE_CODE (exprx) == COMPONENT_REF | |
| 2045 && TREE_CODE (expry) == COMPONENT_REF | |
| 2046 && nonoverlapping_component_refs_p (exprx, expry)) | |
| 2047 return 1; | |
| 2048 | |
| 2049 | |
| 2050 /* If the field reference test failed, look at the DECLs involved. */ | |
| 2051 moffsetx = MEM_OFFSET (x); | |
| 2052 if (TREE_CODE (exprx) == COMPONENT_REF) | |
| 2053 { | |
| 2054 if (TREE_CODE (expry) == VAR_DECL | |
| 2055 && POINTER_TYPE_P (TREE_TYPE (expry))) | |
| 2056 { | |
| 2057 tree field = TREE_OPERAND (exprx, 1); | |
| 2058 tree fieldcontext = DECL_FIELD_CONTEXT (field); | |
| 2059 if (ipa_type_escape_field_does_not_clobber_p (fieldcontext, | |
| 2060 TREE_TYPE (field))) | |
| 2061 return 1; | |
| 2062 } | |
| 2063 { | |
| 2064 tree t = decl_for_component_ref (exprx); | |
| 2065 if (! t) | |
| 2066 return 0; | |
| 2067 moffsetx = adjust_offset_for_component_ref (exprx, moffsetx); | |
| 2068 exprx = t; | |
| 2069 } | |
| 2070 } | |
| 2071 else if (INDIRECT_REF_P (exprx)) | |
| 2072 { | |
| 2073 exprx = TREE_OPERAND (exprx, 0); | |
| 2074 if (flag_argument_noalias < 2 | |
| 2075 || TREE_CODE (exprx) != PARM_DECL) | |
| 2076 return 0; | |
| 2077 } | |
| 2078 | |
| 2079 moffsety = MEM_OFFSET (y); | |
| 2080 if (TREE_CODE (expry) == COMPONENT_REF) | |
| 2081 { | |
| 2082 if (TREE_CODE (exprx) == VAR_DECL | |
| 2083 && POINTER_TYPE_P (TREE_TYPE (exprx))) | |
| 2084 { | |
| 2085 tree field = TREE_OPERAND (expry, 1); | |
| 2086 tree fieldcontext = DECL_FIELD_CONTEXT (field); | |
| 2087 if (ipa_type_escape_field_does_not_clobber_p (fieldcontext, | |
| 2088 TREE_TYPE (field))) | |
| 2089 return 1; | |
| 2090 } | |
| 2091 { | |
| 2092 tree t = decl_for_component_ref (expry); | |
| 2093 if (! t) | |
| 2094 return 0; | |
| 2095 moffsety = adjust_offset_for_component_ref (expry, moffsety); | |
| 2096 expry = t; | |
| 2097 } | |
| 2098 } | |
| 2099 else if (INDIRECT_REF_P (expry)) | |
| 2100 { | |
| 2101 expry = TREE_OPERAND (expry, 0); | |
| 2102 if (flag_argument_noalias < 2 | |
| 2103 || TREE_CODE (expry) != PARM_DECL) | |
| 2104 return 0; | |
| 2105 } | |
| 2106 | |
| 2107 if (! DECL_P (exprx) || ! DECL_P (expry)) | |
| 2108 return 0; | |
| 2109 | |
| 2110 rtlx = DECL_RTL (exprx); | |
| 2111 rtly = DECL_RTL (expry); | |
| 2112 | |
| 2113 /* If either RTL is not a MEM, it must be a REG or CONCAT, meaning they | |
| 2114 can't overlap unless they are the same because we never reuse that part | |
| 2115 of the stack frame used for locals for spilled pseudos. */ | |
| 2116 if ((!MEM_P (rtlx) || !MEM_P (rtly)) | |
| 2117 && ! rtx_equal_p (rtlx, rtly)) | |
| 2118 return 1; | |
| 2119 | |
| 2120 /* Get the base and offsets of both decls. If either is a register, we | |
| 2121 know both are and are the same, so use that as the base. The only | |
| 2122 we can avoid overlap is if we can deduce that they are nonoverlapping | |
| 2123 pieces of that decl, which is very rare. */ | |
| 2124 basex = MEM_P (rtlx) ? XEXP (rtlx, 0) : rtlx; | |
| 2125 if (GET_CODE (basex) == PLUS && GET_CODE (XEXP (basex, 1)) == CONST_INT) | |
| 2126 offsetx = INTVAL (XEXP (basex, 1)), basex = XEXP (basex, 0); | |
| 2127 | |
| 2128 basey = MEM_P (rtly) ? XEXP (rtly, 0) : rtly; | |
| 2129 if (GET_CODE (basey) == PLUS && GET_CODE (XEXP (basey, 1)) == CONST_INT) | |
| 2130 offsety = INTVAL (XEXP (basey, 1)), basey = XEXP (basey, 0); | |
| 2131 | |
| 2132 /* If the bases are different, we know they do not overlap if both | |
| 2133 are constants or if one is a constant and the other a pointer into the | |
| 2134 stack frame. Otherwise a different base means we can't tell if they | |
| 2135 overlap or not. */ | |
| 2136 if (! rtx_equal_p (basex, basey)) | |
| 2137 return ((CONSTANT_P (basex) && CONSTANT_P (basey)) | |
| 2138 || (CONSTANT_P (basex) && REG_P (basey) | |
| 2139 && REGNO_PTR_FRAME_P (REGNO (basey))) | |
| 2140 || (CONSTANT_P (basey) && REG_P (basex) | |
| 2141 && REGNO_PTR_FRAME_P (REGNO (basex)))); | |
| 2142 | |
| 2143 sizex = (!MEM_P (rtlx) ? (int) GET_MODE_SIZE (GET_MODE (rtlx)) | |
| 2144 : MEM_SIZE (rtlx) ? INTVAL (MEM_SIZE (rtlx)) | |
| 2145 : -1); | |
| 2146 sizey = (!MEM_P (rtly) ? (int) GET_MODE_SIZE (GET_MODE (rtly)) | |
| 2147 : MEM_SIZE (rtly) ? INTVAL (MEM_SIZE (rtly)) : | |
| 2148 -1); | |
| 2149 | |
| 2150 /* If we have an offset for either memref, it can update the values computed | |
| 2151 above. */ | |
| 2152 if (moffsetx) | |
| 2153 offsetx += INTVAL (moffsetx), sizex -= INTVAL (moffsetx); | |
| 2154 if (moffsety) | |
| 2155 offsety += INTVAL (moffsety), sizey -= INTVAL (moffsety); | |
| 2156 | |
| 2157 /* If a memref has both a size and an offset, we can use the smaller size. | |
| 2158 We can't do this if the offset isn't known because we must view this | |
| 2159 memref as being anywhere inside the DECL's MEM. */ | |
| 2160 if (MEM_SIZE (x) && moffsetx) | |
| 2161 sizex = INTVAL (MEM_SIZE (x)); | |
| 2162 if (MEM_SIZE (y) && moffsety) | |
| 2163 sizey = INTVAL (MEM_SIZE (y)); | |
| 2164 | |
| 2165 /* Put the values of the memref with the lower offset in X's values. */ | |
| 2166 if (offsetx > offsety) | |
| 2167 { | |
| 2168 tem = offsetx, offsetx = offsety, offsety = tem; | |
| 2169 tem = sizex, sizex = sizey, sizey = tem; | |
| 2170 } | |
| 2171 | |
| 2172 /* If we don't know the size of the lower-offset value, we can't tell | |
| 2173 if they conflict. Otherwise, we do the test. */ | |
| 2174 return sizex >= 0 && offsety >= offsetx + sizex; | |
| 2175 } | |
| 2176 | |
| 2177 /* True dependence: X is read after store in MEM takes place. */ | |
| 2178 | |
| 2179 int | |
| 2180 true_dependence (const_rtx mem, enum machine_mode mem_mode, const_rtx x, | |
| 2181 bool (*varies) (const_rtx, bool)) | |
| 2182 { | |
| 2183 rtx x_addr, mem_addr; | |
| 2184 rtx base; | |
| 2185 | |
| 2186 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) | |
| 2187 return 1; | |
| 2188 | |
| 2189 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything. | |
| 2190 This is used in epilogue deallocation functions, and in cselib. */ | |
| 2191 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH) | |
| 2192 return 1; | |
| 2193 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH) | |
| 2194 return 1; | |
| 2195 if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER | |
| 2196 || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) | |
| 2197 return 1; | |
| 2198 | |
| 2199 if (DIFFERENT_ALIAS_SETS_P (x, mem)) | |
| 2200 return 0; | |
| 2201 | |
| 2202 /* Read-only memory is by definition never modified, and therefore can't | |
| 2203 conflict with anything. We don't expect to find read-only set on MEM, | |
| 2204 but stupid user tricks can produce them, so don't die. */ | |
| 2205 if (MEM_READONLY_P (x)) | |
| 2206 return 0; | |
| 2207 | |
| 2208 if (nonoverlapping_memrefs_p (mem, x)) | |
| 2209 return 0; | |
| 2210 | |
| 2211 if (mem_mode == VOIDmode) | |
| 2212 mem_mode = GET_MODE (mem); | |
| 2213 | |
| 2214 x_addr = get_addr (XEXP (x, 0)); | |
| 2215 mem_addr = get_addr (XEXP (mem, 0)); | |
| 2216 | |
| 2217 base = find_base_term (x_addr); | |
| 2218 if (base && (GET_CODE (base) == LABEL_REF | |
| 2219 || (GET_CODE (base) == SYMBOL_REF | |
| 2220 && CONSTANT_POOL_ADDRESS_P (base)))) | |
| 2221 return 0; | |
| 2222 | |
| 2223 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode)) | |
| 2224 return 0; | |
| 2225 | |
| 2226 x_addr = canon_rtx (x_addr); | |
| 2227 mem_addr = canon_rtx (mem_addr); | |
| 2228 | |
| 2229 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr, | |
| 2230 SIZE_FOR_MODE (x), x_addr, 0)) | |
| 2231 return 0; | |
| 2232 | |
| 2233 if (aliases_everything_p (x)) | |
| 2234 return 1; | |
| 2235 | |
| 2236 /* We cannot use aliases_everything_p to test MEM, since we must look | |
| 2237 at MEM_MODE, rather than GET_MODE (MEM). */ | |
| 2238 if (mem_mode == QImode || GET_CODE (mem_addr) == AND) | |
| 2239 return 1; | |
| 2240 | |
| 2241 /* In true_dependence we also allow BLKmode to alias anything. Why | |
| 2242 don't we do this in anti_dependence and output_dependence? */ | |
| 2243 if (mem_mode == BLKmode || GET_MODE (x) == BLKmode) | |
| 2244 return 1; | |
| 2245 | |
| 2246 return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr, | |
| 2247 varies); | |
| 2248 } | |
| 2249 | |
| 2250 /* Canonical true dependence: X is read after store in MEM takes place. | |
| 2251 Variant of true_dependence which assumes MEM has already been | |
| 2252 canonicalized (hence we no longer do that here). | |
| 2253 The mem_addr argument has been added, since true_dependence computed | |
|
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|
2254 this value prior to canonicalizing. |
|
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update gcc from 4.4.0 to 4.4.1.
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parents:
0
diff
changeset
|
2255 If x_addr is non-NULL, it is used in preference of XEXP (x, 0). */ |
| 0 | 2256 |
| 2257 int | |
| 2258 canon_true_dependence (const_rtx mem, enum machine_mode mem_mode, rtx mem_addr, | |
|
19
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update gcc from 4.4.0 to 4.4.1.
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parents:
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diff
changeset
|
2259 const_rtx x, rtx x_addr, bool (*varies) (const_rtx, bool)) |
| 0 | 2260 { |
| 2261 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) | |
| 2262 return 1; | |
| 2263 | |
| 2264 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything. | |
| 2265 This is used in epilogue deallocation functions. */ | |
| 2266 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH) | |
| 2267 return 1; | |
| 2268 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH) | |
| 2269 return 1; | |
| 2270 if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER | |
| 2271 || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) | |
| 2272 return 1; | |
| 2273 | |
| 2274 if (DIFFERENT_ALIAS_SETS_P (x, mem)) | |
| 2275 return 0; | |
| 2276 | |
| 2277 /* Read-only memory is by definition never modified, and therefore can't | |
| 2278 conflict with anything. We don't expect to find read-only set on MEM, | |
| 2279 but stupid user tricks can produce them, so don't die. */ | |
| 2280 if (MEM_READONLY_P (x)) | |
| 2281 return 0; | |
| 2282 | |
| 2283 if (nonoverlapping_memrefs_p (x, mem)) | |
| 2284 return 0; | |
| 2285 | |
|
19
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update gcc from 4.4.0 to 4.4.1.
kent@firefly.cr.ie.u-ryukyu.ac.jp
parents:
0
diff
changeset
|
2286 if (! x_addr) |
|
58ad6c70ea60
update gcc from 4.4.0 to 4.4.1.
kent@firefly.cr.ie.u-ryukyu.ac.jp
parents:
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diff
changeset
|
2287 x_addr = get_addr (XEXP (x, 0)); |
| 0 | 2288 |
| 2289 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), mem_mode)) | |
| 2290 return 0; | |
| 2291 | |
| 2292 x_addr = canon_rtx (x_addr); | |
| 2293 if (! memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr, | |
| 2294 SIZE_FOR_MODE (x), x_addr, 0)) | |
| 2295 return 0; | |
| 2296 | |
| 2297 if (aliases_everything_p (x)) | |
| 2298 return 1; | |
| 2299 | |
| 2300 /* We cannot use aliases_everything_p to test MEM, since we must look | |
| 2301 at MEM_MODE, rather than GET_MODE (MEM). */ | |
| 2302 if (mem_mode == QImode || GET_CODE (mem_addr) == AND) | |
| 2303 return 1; | |
| 2304 | |
| 2305 /* In true_dependence we also allow BLKmode to alias anything. Why | |
| 2306 don't we do this in anti_dependence and output_dependence? */ | |
| 2307 if (mem_mode == BLKmode || GET_MODE (x) == BLKmode) | |
| 2308 return 1; | |
| 2309 | |
| 2310 return ! fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr, | |
| 2311 varies); | |
| 2312 } | |
| 2313 | |
| 2314 /* Returns nonzero if a write to X might alias a previous read from | |
| 2315 (or, if WRITEP is nonzero, a write to) MEM. */ | |
| 2316 | |
| 2317 static int | |
| 2318 write_dependence_p (const_rtx mem, const_rtx x, int writep) | |
| 2319 { | |
| 2320 rtx x_addr, mem_addr; | |
| 2321 const_rtx fixed_scalar; | |
| 2322 rtx base; | |
| 2323 | |
| 2324 if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem)) | |
| 2325 return 1; | |
| 2326 | |
| 2327 /* (mem:BLK (scratch)) is a special mechanism to conflict with everything. | |
| 2328 This is used in epilogue deallocation functions. */ | |
| 2329 if (GET_MODE (x) == BLKmode && GET_CODE (XEXP (x, 0)) == SCRATCH) | |
| 2330 return 1; | |
| 2331 if (GET_MODE (mem) == BLKmode && GET_CODE (XEXP (mem, 0)) == SCRATCH) | |
| 2332 return 1; | |
| 2333 if (MEM_ALIAS_SET (x) == ALIAS_SET_MEMORY_BARRIER | |
| 2334 || MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) | |
| 2335 return 1; | |
| 2336 | |
| 2337 if (DIFFERENT_ALIAS_SETS_P (x, mem)) | |
| 2338 return 0; | |
| 2339 | |
| 2340 /* A read from read-only memory can't conflict with read-write memory. */ | |
| 2341 if (!writep && MEM_READONLY_P (mem)) | |
| 2342 return 0; | |
| 2343 | |
| 2344 if (nonoverlapping_memrefs_p (x, mem)) | |
| 2345 return 0; | |
| 2346 | |
| 2347 x_addr = get_addr (XEXP (x, 0)); | |
| 2348 mem_addr = get_addr (XEXP (mem, 0)); | |
| 2349 | |
| 2350 if (! writep) | |
| 2351 { | |
| 2352 base = find_base_term (mem_addr); | |
| 2353 if (base && (GET_CODE (base) == LABEL_REF | |
| 2354 || (GET_CODE (base) == SYMBOL_REF | |
| 2355 && CONSTANT_POOL_ADDRESS_P (base)))) | |
| 2356 return 0; | |
| 2357 } | |
| 2358 | |
| 2359 if (! base_alias_check (x_addr, mem_addr, GET_MODE (x), | |
| 2360 GET_MODE (mem))) | |
| 2361 return 0; | |
| 2362 | |
| 2363 x_addr = canon_rtx (x_addr); | |
| 2364 mem_addr = canon_rtx (mem_addr); | |
| 2365 | |
| 2366 if (!memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr, | |
| 2367 SIZE_FOR_MODE (x), x_addr, 0)) | |
| 2368 return 0; | |
| 2369 | |
| 2370 fixed_scalar | |
| 2371 = fixed_scalar_and_varying_struct_p (mem, x, mem_addr, x_addr, | |
| 2372 rtx_addr_varies_p); | |
| 2373 | |
| 2374 return (!(fixed_scalar == mem && !aliases_everything_p (x)) | |
| 2375 && !(fixed_scalar == x && !aliases_everything_p (mem))); | |
| 2376 } | |
| 2377 | |
| 2378 /* Anti dependence: X is written after read in MEM takes place. */ | |
| 2379 | |
| 2380 int | |
| 2381 anti_dependence (const_rtx mem, const_rtx x) | |
| 2382 { | |
| 2383 return write_dependence_p (mem, x, /*writep=*/0); | |
| 2384 } | |
| 2385 | |
| 2386 /* Output dependence: X is written after store in MEM takes place. */ | |
| 2387 | |
| 2388 int | |
| 2389 output_dependence (const_rtx mem, const_rtx x) | |
| 2390 { | |
| 2391 return write_dependence_p (mem, x, /*writep=*/1); | |
| 2392 } | |
| 2393 | |
| 2394 | |
| 2395 void | |
| 2396 init_alias_target (void) | |
| 2397 { | |
| 2398 int i; | |
| 2399 | |
| 2400 memset (static_reg_base_value, 0, sizeof static_reg_base_value); | |
| 2401 | |
| 2402 for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) | |
| 2403 /* Check whether this register can hold an incoming pointer | |
| 2404 argument. FUNCTION_ARG_REGNO_P tests outgoing register | |
| 2405 numbers, so translate if necessary due to register windows. */ | |
| 2406 if (FUNCTION_ARG_REGNO_P (OUTGOING_REGNO (i)) | |
| 2407 && HARD_REGNO_MODE_OK (i, Pmode)) | |
| 2408 static_reg_base_value[i] | |
| 2409 = gen_rtx_ADDRESS (VOIDmode, gen_rtx_REG (Pmode, i)); | |
| 2410 | |
| 2411 static_reg_base_value[STACK_POINTER_REGNUM] | |
| 2412 = gen_rtx_ADDRESS (Pmode, stack_pointer_rtx); | |
| 2413 static_reg_base_value[ARG_POINTER_REGNUM] | |
| 2414 = gen_rtx_ADDRESS (Pmode, arg_pointer_rtx); | |
| 2415 static_reg_base_value[FRAME_POINTER_REGNUM] | |
| 2416 = gen_rtx_ADDRESS (Pmode, frame_pointer_rtx); | |
| 2417 #if HARD_FRAME_POINTER_REGNUM != FRAME_POINTER_REGNUM | |
| 2418 static_reg_base_value[HARD_FRAME_POINTER_REGNUM] | |
| 2419 = gen_rtx_ADDRESS (Pmode, hard_frame_pointer_rtx); | |
| 2420 #endif | |
| 2421 } | |
| 2422 | |
| 2423 /* Set MEMORY_MODIFIED when X modifies DATA (that is assumed | |
| 2424 to be memory reference. */ | |
| 2425 static bool memory_modified; | |
| 2426 static void | |
| 2427 memory_modified_1 (rtx x, const_rtx pat ATTRIBUTE_UNUSED, void *data) | |
| 2428 { | |
| 2429 if (MEM_P (x)) | |
| 2430 { | |
| 2431 if (anti_dependence (x, (const_rtx)data) || output_dependence (x, (const_rtx)data)) | |
| 2432 memory_modified = true; | |
| 2433 } | |
| 2434 } | |
| 2435 | |
| 2436 | |
| 2437 /* Return true when INSN possibly modify memory contents of MEM | |
| 2438 (i.e. address can be modified). */ | |
| 2439 bool | |
| 2440 memory_modified_in_insn_p (const_rtx mem, const_rtx insn) | |
| 2441 { | |
| 2442 if (!INSN_P (insn)) | |
| 2443 return false; | |
| 2444 memory_modified = false; | |
| 2445 note_stores (PATTERN (insn), memory_modified_1, CONST_CAST_RTX(mem)); | |
| 2446 return memory_modified; | |
| 2447 } | |
| 2448 | |
| 2449 /* Initialize the aliasing machinery. Initialize the REG_KNOWN_VALUE | |
| 2450 array. */ | |
| 2451 | |
| 2452 void | |
| 2453 init_alias_analysis (void) | |
| 2454 { | |
| 2455 unsigned int maxreg = max_reg_num (); | |
| 2456 int changed, pass; | |
| 2457 int i; | |
| 2458 unsigned int ui; | |
| 2459 rtx insn; | |
| 2460 | |
| 2461 timevar_push (TV_ALIAS_ANALYSIS); | |
| 2462 | |
| 2463 reg_known_value_size = maxreg - FIRST_PSEUDO_REGISTER; | |
| 2464 reg_known_value = GGC_CNEWVEC (rtx, reg_known_value_size); | |
| 2465 reg_known_equiv_p = XCNEWVEC (bool, reg_known_value_size); | |
| 2466 | |
| 2467 /* If we have memory allocated from the previous run, use it. */ | |
| 2468 if (old_reg_base_value) | |
| 2469 reg_base_value = old_reg_base_value; | |
| 2470 | |
| 2471 if (reg_base_value) | |
| 2472 VEC_truncate (rtx, reg_base_value, 0); | |
| 2473 | |
| 2474 VEC_safe_grow_cleared (rtx, gc, reg_base_value, maxreg); | |
| 2475 | |
| 2476 new_reg_base_value = XNEWVEC (rtx, maxreg); | |
| 2477 reg_seen = XNEWVEC (char, maxreg); | |
| 2478 | |
| 2479 /* The basic idea is that each pass through this loop will use the | |
| 2480 "constant" information from the previous pass to propagate alias | |
| 2481 information through another level of assignments. | |
| 2482 | |
| 2483 This could get expensive if the assignment chains are long. Maybe | |
| 2484 we should throttle the number of iterations, possibly based on | |
| 2485 the optimization level or flag_expensive_optimizations. | |
| 2486 | |
| 2487 We could propagate more information in the first pass by making use | |
| 2488 of DF_REG_DEF_COUNT to determine immediately that the alias information | |
| 2489 for a pseudo is "constant". | |
| 2490 | |
| 2491 A program with an uninitialized variable can cause an infinite loop | |
| 2492 here. Instead of doing a full dataflow analysis to detect such problems | |
| 2493 we just cap the number of iterations for the loop. | |
| 2494 | |
| 2495 The state of the arrays for the set chain in question does not matter | |
| 2496 since the program has undefined behavior. */ | |
| 2497 | |
| 2498 pass = 0; | |
| 2499 do | |
| 2500 { | |
| 2501 /* Assume nothing will change this iteration of the loop. */ | |
| 2502 changed = 0; | |
| 2503 | |
| 2504 /* We want to assign the same IDs each iteration of this loop, so | |
| 2505 start counting from zero each iteration of the loop. */ | |
| 2506 unique_id = 0; | |
| 2507 | |
| 2508 /* We're at the start of the function each iteration through the | |
| 2509 loop, so we're copying arguments. */ | |
| 2510 copying_arguments = true; | |
| 2511 | |
| 2512 /* Wipe the potential alias information clean for this pass. */ | |
| 2513 memset (new_reg_base_value, 0, maxreg * sizeof (rtx)); | |
| 2514 | |
| 2515 /* Wipe the reg_seen array clean. */ | |
| 2516 memset (reg_seen, 0, maxreg); | |
| 2517 | |
| 2518 /* Mark all hard registers which may contain an address. | |
| 2519 The stack, frame and argument pointers may contain an address. | |
| 2520 An argument register which can hold a Pmode value may contain | |
| 2521 an address even if it is not in BASE_REGS. | |
| 2522 | |
| 2523 The address expression is VOIDmode for an argument and | |
| 2524 Pmode for other registers. */ | |
| 2525 | |
| 2526 memcpy (new_reg_base_value, static_reg_base_value, | |
| 2527 FIRST_PSEUDO_REGISTER * sizeof (rtx)); | |
| 2528 | |
| 2529 /* Walk the insns adding values to the new_reg_base_value array. */ | |
| 2530 for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) | |
| 2531 { | |
| 2532 if (INSN_P (insn)) | |
| 2533 { | |
| 2534 rtx note, set; | |
| 2535 | |
| 2536 #if defined (HAVE_prologue) || defined (HAVE_epilogue) | |
| 2537 /* The prologue/epilogue insns are not threaded onto the | |
| 2538 insn chain until after reload has completed. Thus, | |
| 2539 there is no sense wasting time checking if INSN is in | |
| 2540 the prologue/epilogue until after reload has completed. */ | |
| 2541 if (reload_completed | |
| 2542 && prologue_epilogue_contains (insn)) | |
| 2543 continue; | |
| 2544 #endif | |
| 2545 | |
| 2546 /* If this insn has a noalias note, process it, Otherwise, | |
| 2547 scan for sets. A simple set will have no side effects | |
| 2548 which could change the base value of any other register. */ | |
| 2549 | |
| 2550 if (GET_CODE (PATTERN (insn)) == SET | |
| 2551 && REG_NOTES (insn) != 0 | |
| 2552 && find_reg_note (insn, REG_NOALIAS, NULL_RTX)) | |
| 2553 record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL); | |
| 2554 else | |
| 2555 note_stores (PATTERN (insn), record_set, NULL); | |
| 2556 | |
| 2557 set = single_set (insn); | |
| 2558 | |
| 2559 if (set != 0 | |
| 2560 && REG_P (SET_DEST (set)) | |
| 2561 && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER) | |
| 2562 { | |
| 2563 unsigned int regno = REGNO (SET_DEST (set)); | |
| 2564 rtx src = SET_SRC (set); | |
| 2565 rtx t; | |
| 2566 | |
| 2567 note = find_reg_equal_equiv_note (insn); | |
| 2568 if (note && REG_NOTE_KIND (note) == REG_EQUAL | |
| 2569 && DF_REG_DEF_COUNT (regno) != 1) | |
| 2570 note = NULL_RTX; | |
| 2571 | |
| 2572 if (note != NULL_RTX | |
| 2573 && GET_CODE (XEXP (note, 0)) != EXPR_LIST | |
| 2574 && ! rtx_varies_p (XEXP (note, 0), 1) | |
| 2575 && ! reg_overlap_mentioned_p (SET_DEST (set), | |
| 2576 XEXP (note, 0))) | |
| 2577 { | |
| 2578 set_reg_known_value (regno, XEXP (note, 0)); | |
| 2579 set_reg_known_equiv_p (regno, | |
| 2580 REG_NOTE_KIND (note) == REG_EQUIV); | |
| 2581 } | |
| 2582 else if (DF_REG_DEF_COUNT (regno) == 1 | |
| 2583 && GET_CODE (src) == PLUS | |
| 2584 && REG_P (XEXP (src, 0)) | |
| 2585 && (t = get_reg_known_value (REGNO (XEXP (src, 0)))) | |
| 2586 && GET_CODE (XEXP (src, 1)) == CONST_INT) | |
| 2587 { | |
| 2588 t = plus_constant (t, INTVAL (XEXP (src, 1))); | |
| 2589 set_reg_known_value (regno, t); | |
| 2590 set_reg_known_equiv_p (regno, 0); | |
| 2591 } | |
| 2592 else if (DF_REG_DEF_COUNT (regno) == 1 | |
| 2593 && ! rtx_varies_p (src, 1)) | |
| 2594 { | |
| 2595 set_reg_known_value (regno, src); | |
| 2596 set_reg_known_equiv_p (regno, 0); | |
| 2597 } | |
| 2598 } | |
| 2599 } | |
| 2600 else if (NOTE_P (insn) | |
| 2601 && NOTE_KIND (insn) == NOTE_INSN_FUNCTION_BEG) | |
| 2602 copying_arguments = false; | |
| 2603 } | |
| 2604 | |
| 2605 /* Now propagate values from new_reg_base_value to reg_base_value. */ | |
| 2606 gcc_assert (maxreg == (unsigned int) max_reg_num ()); | |
| 2607 | |
| 2608 for (ui = 0; ui < maxreg; ui++) | |
| 2609 { | |
| 2610 if (new_reg_base_value[ui] | |
| 2611 && new_reg_base_value[ui] != VEC_index (rtx, reg_base_value, ui) | |
| 2612 && ! rtx_equal_p (new_reg_base_value[ui], | |
| 2613 VEC_index (rtx, reg_base_value, ui))) | |
| 2614 { | |
| 2615 VEC_replace (rtx, reg_base_value, ui, new_reg_base_value[ui]); | |
| 2616 changed = 1; | |
| 2617 } | |
| 2618 } | |
| 2619 } | |
| 2620 while (changed && ++pass < MAX_ALIAS_LOOP_PASSES); | |
| 2621 | |
| 2622 /* Fill in the remaining entries. */ | |
| 2623 for (i = 0; i < (int)reg_known_value_size; i++) | |
| 2624 if (reg_known_value[i] == 0) | |
| 2625 reg_known_value[i] = regno_reg_rtx[i + FIRST_PSEUDO_REGISTER]; | |
| 2626 | |
| 2627 /* Clean up. */ | |
| 2628 free (new_reg_base_value); | |
| 2629 new_reg_base_value = 0; | |
| 2630 free (reg_seen); | |
| 2631 reg_seen = 0; | |
| 2632 timevar_pop (TV_ALIAS_ANALYSIS); | |
| 2633 } | |
| 2634 | |
| 2635 void | |
| 2636 end_alias_analysis (void) | |
| 2637 { | |
| 2638 old_reg_base_value = reg_base_value; | |
| 2639 ggc_free (reg_known_value); | |
| 2640 reg_known_value = 0; | |
| 2641 reg_known_value_size = 0; | |
| 2642 free (reg_known_equiv_p); | |
| 2643 reg_known_equiv_p = 0; | |
| 2644 } | |
| 2645 | |
| 2646 #include "gt-alias.h" |