2 * Copyright (C) 1995-2007 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief Memory disambiguator
23 * @author Michael Beck
34 #include "irgraph_t.h"
44 /** The source language specific language disambiguator function. */
45 static DISAMBIGUATOR_FUNC language_disambuigator = NULL;
47 /** The global memory disambiguator options. */
48 static unsigned global_mem_disamgig_opt = aa_opt_no_opt;
50 /* Get the memory disambiguator options for a graph. */
51 unsigned get_irg_memory_disambiguator_options(ir_graph *irg) {
52 unsigned opt = irg->mem_disambig_opt;
53 if (opt & aa_opt_inherited)
54 return global_mem_disamgig_opt;
56 } /* get_irg_memory_disambiguator_options */
58 /* Set the memory disambiguator options for a graph. */
59 void set_irg_memory_disambiguator_options(ir_graph *irg, unsigned options) {
60 irg->mem_disambig_opt = options & ~aa_opt_inherited;
61 } /* set_irg_memory_disambiguator_options */
63 /* Set the global disambiguator options for all graphs not having local options. */
64 void set_irp_memory_disambiguator_options(unsigned options) {
65 global_mem_disamgig_opt = options;
66 } /* set_irp_memory_disambiguator_options */
69 * Find the base address and entity of an Sel node.
72 * @param pEnt after return points to the base entity.
74 * @return the base address.
76 static ir_node *find_base_adr(ir_node *sel, ir_entity **pEnt) {
77 ir_node *ptr = get_Sel_ptr(sel);
81 ptr = get_Sel_ptr(sel);
83 *pEnt = get_Sel_entity(sel);
88 * Check if the address can be decomposed into base PLUS offset.
90 static int has_offset(ir_node *adr, int *offset) {
91 if (is_SymConst(adr)) {
96 ir_entity *ent = get_Sel_entity(adr);
97 ir_type *owner = get_entity_owner(ent);
99 if (get_type_state(owner) != layout_fixed) {
100 /* The layout is NOT fixed yet, symbolic evaluation needed */
107 * Two address expressions have the same base address,
108 * check if there offsets are different.
110 * @param adr1 The first address.
111 * @param adr2 The second address.
113 static ir_alias_relation different_offsets(ir_node *adr1, ir_node *adr2) {
114 int offset1, offset2;
115 if (has_offset(adr1, &offset1) && has_offset(adr2, &offset2)) {
119 } /* different_offsets */
122 * Determine the alias relation by checking if adr1 and adr2 are pointer
125 * @param adr1 The first address.
126 * @param adr2 The second address.
128 static ir_alias_relation different_types(ir_node *adr1, ir_node *adr2)
130 ir_entity *ent1 = NULL, *ent2 = NULL;
132 if (is_SymConst(adr1) && get_SymConst_kind(adr1) == symconst_addr_ent)
133 ent1 = get_SymConst_entity(adr1);
134 else if (is_Sel(adr1))
135 ent1 = get_Sel_entity(adr1);
137 if (is_SymConst(adr2) && get_SymConst_kind(adr2) == symconst_addr_ent)
138 ent2 = get_SymConst_entity(adr2);
139 else if (is_Sel(adr2))
140 ent2 = get_Sel_entity(adr2);
142 if (ent1 != NULL && ent2 != NULL) {
143 ir_type *tp1 = get_entity_type(ent1);
144 ir_type *tp2 = get_entity_type(ent2);
147 if (is_Pointer_type(tp1) && is_Pointer_type(tp2)) {
148 /* do deref until no pointer types are found */
150 tp1 = get_pointer_points_to_type(tp1);
151 tp2 = get_pointer_points_to_type(tp2);
152 } while (is_Pointer_type(tp1) && is_Pointer_type(tp2));
155 if (get_type_tpop(tp1) != get_type_tpop(tp2)) {
156 /* different type structure */
159 if (is_Class_type(tp1)) {
160 /* check class hierarchy */
161 if (! is_SubClass_of(tp1, tp2) &&
162 ! is_SubClass_of(tp2, tp1))
165 /* different types */
171 } /* different_types */
174 * Returns non-zero if a node is a routine parameter.
176 * @param node the node to test
178 static int is_arg_Proj(ir_node *node) {
181 node = get_Proj_pred(node);
184 return pn_Start_T_args == get_Proj_proj(node) && is_Start(get_Proj_pred(node));
188 * Determine the alias relation between two addresses.
190 static ir_alias_relation _get_alias_relation(
192 ir_node *adr1, ir_mode *mode1,
193 ir_node *adr2, ir_mode *mode2)
196 ir_entity *ent1, *ent2;
199 if (! get_opt_alias_analysis())
205 options = get_irg_memory_disambiguator_options(irg);
207 /* The Armageddon switch */
208 if (options & aa_opt_no_alias)
211 /* Two save some code, sort the addresses by its id's. Beware, this
212 might break some things, so better check here. */
213 assert(iro_SymConst < iro_Sel && iro_Sel < iro_Proj && "Code dependence breaked");
214 op1 = get_irn_opcode(adr1);
215 op2 = get_irn_opcode(adr2);
226 if (is_SymConst(adr1) && get_SymConst_kind(adr1) == symconst_addr_ent) {
227 /* first address is a global variable */
229 if (is_SymConst(adr2) && get_SymConst_kind(adr2) == symconst_addr_ent) {
230 /* both addresses are global variables and we know
231 they are different (R1 a) */
232 if (get_SymConst_entity(adr1) != get_SymConst_entity(adr2))
235 /* equal addresses */
240 ir_node *base = find_base_adr(adr2, &ent2);
242 if (is_SymConst(base) && get_SymConst_kind(base) == symconst_addr_ent) {
243 /* base address is a global var (R1 a) */
247 return different_offsets(adr1, adr2);
248 } else if (base == get_irg_frame(irg)) {
249 /* the second one is a local variable so they are always
252 } else if (base == get_irg_tls(irg)) {
253 /* the second one is a TLS variable so they are always
259 /* Here we are: the first is a global var, the second some pointer. */
260 ent1 = get_SymConst_entity(adr1);
261 if (get_entity_address_taken(ent1) == ir_address_not_taken) {
262 /* The address of the global variable was never taken, so
263 the pointer cannot match (R2). */
266 } else if (is_Sel(adr1)) {
267 /* the first address is a Sel */
268 ir_node *base1 = find_base_adr(adr1, &ent1);
270 if (base1 == get_irg_frame(irg)) {
271 /* the first is a local variable */
273 /* the second address is a Sel */
274 ir_node *base2 = find_base_adr(adr2, &ent2);
276 if (base2 == get_irg_frame(irg)) {
277 /* both addresses are local variables and we know
278 they are different (R1 a) */
282 return different_offsets(adr1, adr2);
283 } else if (base2 == get_irg_tls(irg)) {
284 /* the second one is a TLS variable so they are always
287 } else if (is_arg_Proj(base2)) {
288 /* the second one is an offset from a parameter so they are
289 always different (R1 e) */
292 } else if (is_arg_Proj(adr2)) {
293 /* a local variable and a parameter are always different (R1 e) */
296 } else if (base1 == get_irg_tls(irg)) {
297 /* the first is a TLS variable */
299 /* the second address is a Sel */
300 ir_node *base2 = find_base_adr(adr2, &ent2);
302 if (base2 == get_irg_frame(irg)) {
303 /* the second one is a local variable so they are always
306 } else if (base2 == get_irg_tls(irg)) {
307 /* both addresses are TLS variables and we know
308 they are different (R1 a) */
312 return different_offsets(adr1, adr2);
315 } else if (is_arg_Proj(base1)) {
316 /* the first one is an offset from a parameter */
318 /* the second address is a Sel */
319 ir_node *base2 = find_base_adr(adr2, &ent2);
321 if (base2 == get_irg_frame(irg)) {
322 /* the second one is a local variable so they are always
330 if (options & aa_opt_type_based) { /* Type based alias analysis */
331 ir_alias_relation rel;
333 if (options & aa_opt_byte_type_may_alias) {
334 if (get_mode_size_bits(mode1) == 8 || get_mode_size_bits(mode2) == 8) {
335 /* One of the modes address a byte. Assume a may_alias and leave
336 the type based check. */
337 goto leave_type_based_alias;
340 /* cheap check: If the mode sizes did not match, the types MUST be different */
341 if (get_mode_size_bits(mode1) != get_mode_size_bits(mode2))
345 rel = different_types(adr1, adr2);
346 if (rel != may_alias)
348 leave_type_based_alias:;
351 /* do we have a language specific memory disambiguator? */
352 if (language_disambuigator) {
353 ir_alias_relation rel = (*language_disambuigator)(irg, adr1, mode1, adr2, mode2);
354 if (rel != may_alias)
358 /* access points-to information here */
360 } /* _get_alias_relation */
363 * Determine the alias relation between two addresses.
365 ir_alias_relation get_alias_relation(
367 ir_node *adr1, ir_mode *mode1,
368 ir_node *adr2, ir_mode *mode2)
370 ir_alias_relation rel = _get_alias_relation(irg, adr1, mode1, adr2, mode2);
372 } /* get_alias_relation */
374 /* Set a source language specific memory disambiguator function. */
375 void set_language_memory_disambiguator(DISAMBIGUATOR_FUNC func) {
376 language_disambuigator = func;
377 } /* set_language_memory_disambiguator */
379 /** The result cache for the memory disambiguator. */
380 static set *result_cache = NULL;
382 /** An entry in the relation cache. */
383 typedef struct mem_disambig_entry {
384 ir_node *adr1; /**< The first address. */
385 ir_node *adr2; /**< The second address. */
386 ir_alias_relation result; /**< The alias relation result. */
387 } mem_disambig_entry;
389 #define HASH_ENTRY(adr1, adr2) (HASH_PTR(adr1) ^ HASH_PTR(adr2))
392 * Compare two relation cache entries.
394 static int cmp_mem_disambig_entry(const void *elt, const void *key, size_t size) {
395 const mem_disambig_entry *p1 = elt;
396 const mem_disambig_entry *p2 = key;
398 return p1->adr1 == p2->adr1 && p1->adr2 == p2->adr2;
399 } /* cmp_mem_disambig_entry */
402 * Initialize the relation cache.
404 void mem_disambig_init(void) {
405 result_cache = new_set(cmp_mem_disambig_entry, 8);
406 } /* mem_disambig_init */
409 * Determine the alias relation between two addresses.
411 ir_alias_relation get_alias_relation_ex(
413 ir_node *adr1, ir_mode *mode1,
414 ir_node *adr2, ir_mode *mode2)
416 mem_disambig_entry key, *entry;
418 if (! get_opt_alias_analysis())
421 if (get_irn_opcode(adr1) > get_irn_opcode(adr2)) {
429 entry = set_find(result_cache, &key, sizeof(key), HASH_ENTRY(adr1, adr2));
431 return entry->result;
433 key.result = get_alias_relation(irg, adr1, mode1, adr2, mode2);
435 set_insert(result_cache, &key, sizeof(key), HASH_ENTRY(adr1, adr2));
437 } /* get_alias_relation_ex */
439 /* Free the relation cache. */
440 void mem_disambig_term(void) {
442 del_set(result_cache);
445 } /* mem_disambig_term */
448 * Check the mode of a Load/Store with the mode of the entity
450 * If the mode of the entity and the Load/Store mode do not match, we
451 * have the bad reinterpret case:
454 * char b = *(char *)&i;
456 * We do NOT count this as one value and return address_taken
458 * However, we support an often used case. If the mode is two-complement
459 * we allow casts between signed/unsigned.
461 * @param mode the mode of the Load/Store
462 * @param ent_mode the mode of the accessed entity
464 * @return non-zero if the Load/Store is a hidden cast, zero else
466 static int is_hidden_cast(ir_mode *mode, ir_mode *ent_mode) {
467 if (ent_mode != mode) {
468 if (ent_mode == NULL ||
469 get_mode_size_bits(ent_mode) != get_mode_size_bits(mode) ||
470 get_mode_sort(ent_mode) != get_mode_sort(mode) ||
471 get_mode_arithmetic(ent_mode) != irma_twos_complement ||
472 get_mode_arithmetic(mode) != irma_twos_complement)
476 } /* is_hidden_cast */
479 * Determine the address_taken state of a node (or it's successor Sels).
481 * @param irn the node
483 static ir_address_taken_state find_address_taken_state(ir_node *irn) {
485 ir_mode *emode, *mode;
489 for (i = get_irn_n_outs(irn) - 1; i >= 0; --i) {
490 ir_node *succ = get_irn_out(irn, i);
492 switch (get_irn_opcode(succ)) {
494 /* check if this load is not a hidden conversion */
495 mode = get_Load_mode(succ);
496 ent = is_SymConst(irn) ? get_SymConst_entity(irn) : get_Sel_entity(irn);
497 emode = get_type_mode(get_entity_type(ent));
498 if (is_hidden_cast(mode, emode))
499 return ir_address_taken;
503 /* check that the node is not the Store's value */
504 value = get_Store_value(succ);
506 return ir_address_taken;
507 /* check if this Store is not a hidden conversion */
508 mode = get_irn_mode(value);
509 ent = is_SymConst(irn) ? get_SymConst_entity(irn) : get_Sel_entity(irn);
510 emode = get_type_mode(get_entity_type(ent));
511 if (is_hidden_cast(mode, emode))
512 return ir_address_taken;
516 /* Check the successor of irn. */
517 ir_address_taken_state res = find_address_taken_state(succ);
518 if (res != ir_address_not_taken)
524 /* Only the call address is not an address taker but
525 this is an uninteresting case, so we ignore it here. */
526 return ir_address_taken;
529 /* another op, the address may be taken */
530 return ir_address_taken_unknown;
533 /* All successors finished, the address is not taken. */
534 return ir_address_not_taken;
535 } /* find_address_taken_state */
538 * Update the "address taken" flag of all frame entities.
540 static void analyse_irg_address_taken(ir_graph *irg) {
541 ir_type *ft = get_irg_frame_type(irg);
545 /* set initial state to not_taken, as this is the "smallest" state */
546 for (i = get_class_n_members(ft) - 1; i >= 0; --i) {
547 ir_entity *ent = get_class_member(ft, i);
549 set_entity_address_taken(ent, ir_address_not_taken);
552 assure_irg_outs(irg);
554 irg_frame = get_irg_frame(irg);
556 for (i = get_irn_n_outs(irg_frame) - 1; i >= 0; --i) {
557 ir_node *succ = get_irn_out(irg_frame, i);
558 ir_address_taken_state state;
561 ir_entity *ent = get_Sel_entity(succ);
563 if (get_entity_address_taken(ent) == ir_address_taken)
566 state = find_address_taken_state(succ);
567 if (state > get_entity_address_taken(ent))
568 set_entity_address_taken(ent, state);
572 irg->adr_taken_state = ir_address_taken_computed;
573 } /* analyse_address_taken */
575 /* Returns the current address taken state of the graph. */
576 ir_address_taken_computed_state get_irg_address_taken_state(const ir_graph *irg) {
577 return irg->adr_taken_state;
578 } /* get_irg_address_taken_state */
580 /* Sets the current address taken state of the graph. */
581 void set_irg_address_taken_state(ir_graph *irg, ir_address_taken_computed_state state) {
582 irg->adr_taken_state = state;
583 } /* set_irg_address_taken_state */
585 /* Assure that the address taken flag is computed for the given graph. */
586 void assure_irg_address_taken_computed(ir_graph *irg) {
587 if (irg->adr_taken_state == ir_address_taken_not_computed)
588 analyse_irg_address_taken(irg);
589 } /* assure_irg_address_taken_computed */
592 * Initialize the address_taken flag for a global type like type.
594 static void init_taken_flag(ir_type * tp) {
597 /* All external visible entities are at least
598 ir_address_taken_unknown. This is very conservative. */
599 for (i = get_compound_n_members(tp) - 1; i >= 0; --i) {
600 ir_entity *ent = get_compound_member(tp, i);
601 ir_address_taken_state state;
603 state = get_entity_visibility(ent) == visibility_external_visible ?
604 ir_address_taken_unknown : ir_address_not_taken ;
605 set_entity_address_taken(ent, state);
607 } /* init_taken_flag */
611 * Print the address taken state of all entities of a given type for debugging.
613 static void print_address_taken_state(ir_type *tp) {
615 for (i = get_compound_n_members(tp) - 1; i >= 0; --i) {
616 ir_entity *ent = get_compound_member(tp, i);
617 ir_address_taken_state state = get_entity_address_taken(ent);
619 if (state != ir_address_not_taken) {
620 assert(ir_address_not_taken <= state && state <= ir_address_taken);
621 ir_printf("%+F: %s\n", ent, get_address_taken_state_name(state));
624 } /* print_address_taken_state */
628 * Post-walker: check for global entity address
630 static void check_global_address(ir_node *irn, void *env) {
633 ir_address_taken_state state;
635 if (is_SymConst(irn) && get_SymConst_kind(irn) == symconst_addr_ent) {
637 ent = get_SymConst_entity(irn);
638 } else if (is_Sel(irn) && get_Sel_ptr(irn) == tls) {
639 /* A TLS variable. */
640 ent = get_Sel_entity(irn);
644 if (get_entity_address_taken(ent) >= ir_address_taken) {
645 /* Already at the maximum. */
648 state = find_address_taken_state(irn);
649 if (state > get_entity_address_taken(ent))
650 set_entity_address_taken(ent, state);
651 } /* check_global_address */
654 * Update the "address taken" flag of all global entities.
656 static void analyse_irp_globals_address_taken(void) {
659 init_taken_flag(get_glob_type());
660 init_taken_flag(get_tls_type());
662 for (i = get_irp_n_irgs() - 1; i >= 0; --i) {
663 ir_graph *irg = get_irp_irg(i);
665 assure_irg_outs(irg);
666 irg_walk_graph(irg, NULL, check_global_address, get_irg_tls(irg));
668 //print_address_taken_state(get_glob_type());
669 //print_address_taken_state(get_tls_type());
672 irp->globals_adr_taken_state = ir_address_taken_computed;
673 } /* analyse_irp_globals_address_taken */
675 /* Returns the current address taken state of the globals. */
676 ir_address_taken_computed_state get_irp_globals_address_taken_state(void) {
677 return irp->globals_adr_taken_state;
678 } /* get_irp_globals_address_taken_state */
680 /* Sets the current address taken state of the graph. */
681 void set_irp_globals_address_taken_state(ir_address_taken_computed_state state) {
682 irp->globals_adr_taken_state = state;
683 } /* set_irg_address_taken_state */
685 /* Assure that the address taken flag is computed for the globals. */
686 void assure_irp_globals_address_taken_computed(void) {
687 if (irp->globals_adr_taken_state == ir_address_taken_not_computed)
688 analyse_irp_globals_address_taken();
689 } /* assure_irp_globals_address_taken_computed */