2 * Copyright (C) 1995-2008 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 Load/Store optimizations.
23 * @author Michael Beck
30 #include "iroptimize.h"
32 #include "irgraph_t.h"
40 #include "dbginfo_t.h"
41 #include "iropt_dbg.h"
47 #include "opt_polymorphy.h"
49 #include "irphase_t.h"
54 /** The debug handle. */
55 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
58 #include "cacheopt/cachesim.h"
62 #define IMAX(a,b) ((a) > (b) ? (a) : (b))
64 #define MAX_PROJ IMAX(IMAX(pn_Load_max, pn_Store_max), pn_Call_max)
67 DF_CHANGED = 1, /**< data flow changed */
68 CF_CHANGED = 2, /**< control flow changed */
74 typedef struct _walk_env_t {
75 struct obstack obst; /**< list of all stores */
76 unsigned changes; /**< a bitmask of graph changes */
79 /** A Load/Store info. */
80 typedef struct _ldst_info_t {
81 ir_node *projs[MAX_PROJ]; /**< list of Proj's of this node */
82 ir_node *exc_block; /**< the exception block if available */
83 int exc_idx; /**< predecessor index in the exception block */
84 unsigned visited; /**< visited counter for breaking loops */
88 * flags for control flow.
91 BLOCK_HAS_COND = 1, /**< Block has conditional control flow */
92 BLOCK_HAS_EXC = 2 /**< Block has exceptional control flow */
98 typedef struct _block_info_t {
99 unsigned flags; /**< flags for the block */
102 /** the master visited flag for loop detection. */
103 static unsigned master_visited = 0;
105 #define INC_MASTER() ++master_visited
106 #define MARK_NODE(info) (info)->visited = master_visited
107 #define NODE_VISITED(info) (info)->visited >= master_visited
110 * get the Load/Store info of a node
112 static ldst_info_t *get_ldst_info(ir_node *node, struct obstack *obst) {
113 ldst_info_t *info = get_irn_link(node);
116 info = obstack_alloc(obst, sizeof(*info));
117 memset(info, 0, sizeof(*info));
118 set_irn_link(node, info);
121 } /* get_ldst_info */
124 * get the Block info of a node
126 static block_info_t *get_block_info(ir_node *node, struct obstack *obst) {
127 block_info_t *info = get_irn_link(node);
130 info = obstack_alloc(obst, sizeof(*info));
131 memset(info, 0, sizeof(*info));
132 set_irn_link(node, info);
135 } /* get_block_info */
138 * update the projection info for a Load/Store
140 static unsigned update_projs(ldst_info_t *info, ir_node *proj)
142 long nr = get_Proj_proj(proj);
144 assert(0 <= nr && nr <= MAX_PROJ && "Wrong proj from LoadStore");
146 if (info->projs[nr]) {
147 /* there is already one, do CSE */
148 exchange(proj, info->projs[nr]);
152 info->projs[nr] = proj;
158 * update the exception block info for a Load/Store node.
160 * @param info the load/store info struct
161 * @param block the exception handler block for this load/store
162 * @param pos the control flow input of the block
164 static unsigned update_exc(ldst_info_t *info, ir_node *block, int pos)
166 assert(info->exc_block == NULL && "more than one exception block found");
168 info->exc_block = block;
173 /** Return the number of uses of an address node */
174 #define get_irn_n_uses(adr) get_irn_n_edges(adr)
177 * walker, collects all Load/Store/Proj nodes
179 * walks from Start -> End
181 static void collect_nodes(ir_node *node, void *env)
183 ir_opcode opcode = get_irn_opcode(node);
184 ir_node *pred, *blk, *pred_blk;
185 ldst_info_t *ldst_info;
186 walk_env_t *wenv = env;
188 if (opcode == iro_Proj) {
189 pred = get_Proj_pred(node);
190 opcode = get_irn_opcode(pred);
192 if (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call) {
193 ldst_info = get_ldst_info(pred, &wenv->obst);
195 wenv->changes |= update_projs(ldst_info, node);
198 * Place the Proj's to the same block as the
199 * predecessor Load. This is always ok and prevents
200 * "non-SSA" form after optimizations if the Proj
201 * is in a wrong block.
203 blk = get_nodes_block(node);
204 pred_blk = get_nodes_block(pred);
205 if (blk != pred_blk) {
206 wenv->changes |= DF_CHANGED;
207 set_nodes_block(node, pred_blk);
210 } else if (opcode == iro_Block) {
213 for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) {
214 ir_node *pred_block, *proj;
215 block_info_t *bl_info;
218 pred = proj = get_Block_cfgpred(node, i);
221 pred = get_Proj_pred(proj);
222 is_exc = get_Proj_proj(proj) == pn_Generic_X_except;
225 /* ignore Bad predecessors, they will be removed later */
229 pred_block = get_nodes_block(pred);
230 bl_info = get_block_info(pred_block, &wenv->obst);
232 if (is_fragile_op(pred) && is_exc)
233 bl_info->flags |= BLOCK_HAS_EXC;
234 else if (is_irn_forking(pred))
235 bl_info->flags |= BLOCK_HAS_COND;
237 opcode = get_irn_opcode(pred);
238 if (is_exc && (opcode == iro_Load || opcode == iro_Store || opcode == iro_Call)) {
239 ldst_info = get_ldst_info(pred, &wenv->obst);
241 wenv->changes |= update_exc(ldst_info, node, i);
245 } /* collect_nodes */
248 * Returns an entity if the address ptr points to a constant one.
250 * @param ptr the address
252 * @return an entity or NULL
254 static ir_entity *find_constant_entity(ir_node *ptr)
257 if (is_SymConst(ptr) && get_SymConst_kind(ptr) == symconst_addr_ent) {
258 return get_SymConst_entity(ptr);
259 } else if (is_Sel(ptr)) {
260 ir_entity *ent = get_Sel_entity(ptr);
261 ir_type *tp = get_entity_owner(ent);
263 /* Do not fiddle with polymorphism. */
264 if (is_Class_type(get_entity_owner(ent)) &&
265 ((get_entity_n_overwrites(ent) != 0) ||
266 (get_entity_n_overwrittenby(ent) != 0) ) )
269 if (is_Array_type(tp)) {
273 for (i = 0, n = get_Sel_n_indexs(ptr); i < n; ++i) {
275 tarval *tlower, *tupper;
276 ir_node *index = get_Sel_index(ptr, i);
277 tarval *tv = computed_value(index);
279 /* check if the index is constant */
280 if (tv == tarval_bad)
283 bound = get_array_lower_bound(tp, i);
284 tlower = computed_value(bound);
285 bound = get_array_upper_bound(tp, i);
286 tupper = computed_value(bound);
288 if (tlower == tarval_bad || tupper == tarval_bad)
291 if (tarval_cmp(tv, tlower) & pn_Cmp_Lt)
293 if (tarval_cmp(tupper, tv) & pn_Cmp_Lt)
296 /* ok, bounds check finished */
300 if (variability_constant == get_entity_variability(ent))
304 ptr = get_Sel_ptr(ptr);
305 } else if (is_Add(ptr)) {
306 ir_node *l = get_Add_left(ptr);
307 ir_node *r = get_Add_right(ptr);
309 if (get_irn_mode(l) == get_irn_mode(ptr) && is_Const(r))
311 else if (get_irn_mode(r) == get_irn_mode(ptr) && is_Const(l))
316 /* for now, we support only one addition, reassoc should fold all others */
317 if (! is_SymConst(ptr) && !is_Sel(ptr))
319 } else if (is_Sub(ptr)) {
320 ir_node *l = get_Sub_left(ptr);
321 ir_node *r = get_Sub_right(ptr);
323 if (get_irn_mode(l) == get_irn_mode(ptr) && is_Const(r))
327 /* for now, we support only one substraction, reassoc should fold all others */
328 if (! is_SymConst(ptr) && !is_Sel(ptr))
333 } /* find_constant_entity */
336 * Return the Selection index of a Sel node from dimension n
338 static long get_Sel_array_index_long(ir_node *n, int dim) {
339 ir_node *index = get_Sel_index(n, dim);
340 assert(is_Const(index));
341 return get_tarval_long(get_Const_tarval(index));
342 } /* get_Sel_array_index_long */
345 * Returns the accessed component graph path for an
346 * node computing an address.
348 * @param ptr the node computing the address
349 * @param depth current depth in steps upward from the root
352 static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth) {
353 compound_graph_path *res = NULL;
354 ir_entity *root, *field, *ent;
355 int path_len, pos, idx;
359 if (is_SymConst(ptr)) {
360 /* a SymConst. If the depth is 0, this is an access to a global
361 * entity and we don't need a component path, else we know
362 * at least its length.
364 assert(get_SymConst_kind(ptr) == symconst_addr_ent);
365 root = get_SymConst_entity(ptr);
366 res = (depth == 0) ? NULL : new_compound_graph_path(get_entity_type(root), depth);
367 } else if (is_Sel(ptr)) {
368 /* it's a Sel, go up until we find the root */
369 res = rec_get_accessed_path(get_Sel_ptr(ptr), depth+1);
373 /* fill up the step in the path at the current position */
374 field = get_Sel_entity(ptr);
375 path_len = get_compound_graph_path_length(res);
376 pos = path_len - depth - 1;
377 set_compound_graph_path_node(res, pos, field);
379 if (is_Array_type(get_entity_owner(field))) {
380 assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
381 set_compound_graph_path_array_index(res, pos, get_Sel_array_index_long(ptr, 0));
383 } else if (is_Add(ptr)) {
384 ir_node *l = get_Add_left(ptr);
385 ir_node *r = get_Add_right(ptr);
386 ir_mode *mode = get_irn_mode(ptr);
389 if (is_Const(r) && get_irn_mode(l) == mode) {
391 tv = get_Const_tarval(r);
394 tv = get_Const_tarval(l);
397 mode = get_tarval_mode(tv);
400 /* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
402 field = get_Sel_entity(ptr);
404 field = get_SymConst_entity(ptr);
407 for (ent = field;;) {
409 tarval *sz, *tv_index, *tlower, *tupper;
412 tp = get_entity_type(ent);
413 if (! is_Array_type(tp))
415 ent = get_array_element_entity(tp);
416 size = get_type_size_bytes(get_entity_type(ent));
417 sz = new_tarval_from_long(size, mode);
419 tv_index = tarval_div(tmp, sz);
420 tmp = tarval_mod(tmp, sz);
422 if (tv_index == tarval_bad || tmp == tarval_bad)
425 assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
426 bound = get_array_lower_bound(tp, 0);
427 tlower = computed_value(bound);
428 bound = get_array_upper_bound(tp, 0);
429 tupper = computed_value(bound);
431 if (tlower == tarval_bad || tupper == tarval_bad)
434 if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
436 if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
439 /* ok, bounds check finished */
442 if (! tarval_is_null(tmp)) {
443 /* access to some struct/union member */
447 /* should be at least ONE array */
451 res = rec_get_accessed_path(ptr, depth + idx);
455 path_len = get_compound_graph_path_length(res);
456 pos = path_len - depth - idx;
458 for (ent = field;;) {
460 tarval *sz, *tv_index;
463 tp = get_entity_type(ent);
464 if (! is_Array_type(tp))
466 ent = get_array_element_entity(tp);
467 set_compound_graph_path_node(res, pos, ent);
469 size = get_type_size_bytes(get_entity_type(ent));
470 sz = new_tarval_from_long(size, mode);
472 tv_index = tarval_div(tv, sz);
473 tv = tarval_mod(tv, sz);
475 /* worked above, should work again */
476 assert(tv_index != tarval_bad && tv != tarval_bad);
478 /* bounds already checked above */
479 index = get_tarval_long(tv_index);
480 set_compound_graph_path_array_index(res, pos, index);
483 } else if (is_Sub(ptr)) {
484 ir_node *l = get_Sub_left(ptr);
485 ir_node *r = get_Sub_right(ptr);
488 tv = get_Const_tarval(r);
493 } /* rec_get_accessed_path */
496 * Returns an access path or NULL. The access path is only
497 * valid, if the graph is in phase_high and _no_ address computation is used.
499 static compound_graph_path *get_accessed_path(ir_node *ptr) {
500 compound_graph_path *gr = rec_get_accessed_path(ptr, 0);
502 } /* get_accessed_path */
504 typedef struct path_entry {
506 struct path_entry *next;
510 static ir_node *rec_find_compound_ent_value(ir_node *ptr, path_entry *next) {
511 path_entry entry, *p;
512 ir_entity *ent, *field;
513 ir_initializer_t *initializer;
519 if (is_SymConst(ptr)) {
521 ent = get_SymConst_entity(ptr);
522 initializer = get_entity_initializer(ent);
523 for (p = next; p != NULL;) {
524 if (initializer->kind != IR_INITIALIZER_COMPOUND)
526 n = get_initializer_compound_n_entries(initializer);
527 tp = get_entity_type(ent);
529 if (is_Array_type(tp)) {
530 ent = get_array_element_entity(tp);
535 initializer = get_initializer_compound_value(initializer, 0);
539 if (p->index >= (int) n)
541 initializer = get_initializer_compound_value(initializer, p->index);
546 tp = get_entity_type(ent);
547 while (is_Array_type(tp)) {
548 ent = get_array_element_entity(tp);
549 tp = get_entity_type(ent);
551 n = get_initializer_compound_n_entries(initializer);
554 initializer = get_initializer_compound_value(initializer, 0);
557 switch (initializer->kind) {
558 case IR_INITIALIZER_CONST:
559 return get_initializer_const_value(initializer);
560 case IR_INITIALIZER_TARVAL:
561 case IR_INITIALIZER_NULL:
565 } else if (is_Sel(ptr)) {
566 entry.ent = field = get_Sel_entity(ptr);
567 tp = get_entity_owner(field);
568 if (is_Array_type(tp)) {
569 assert(get_Sel_n_indexs(ptr) == 1 && "multi dim arrays not implemented");
570 entry.index = get_Sel_array_index_long(ptr, 0) - get_array_lower_bound_int(tp, 0);
572 int i, n_members = get_compound_n_members(tp);
573 for (i = 0; i < n_members; ++i) {
574 if (get_compound_member(tp, i) == field)
577 if (i >= n_members) {
578 /* not found: should NOT happen */
583 return rec_find_compound_ent_value(get_Sel_ptr(ptr), &entry);
584 } else if (is_Add(ptr)) {
585 ir_node *l = get_Add_left(ptr);
586 ir_node *r = get_Add_right(ptr);
592 tv = get_Const_tarval(r);
595 tv = get_Const_tarval(l);
598 mode = get_tarval_mode(tv);
600 /* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
602 field = get_Sel_entity(ptr);
604 field = get_SymConst_entity(ptr);
607 /* count needed entries */
609 for (ent = field;;) {
610 tp = get_entity_type(ent);
611 if (! is_Array_type(tp))
613 ent = get_array_element_entity(tp);
616 /* should be at least ONE entry */
620 /* allocate the right number of entries */
621 NEW_ARR_A(path_entry, p, pos);
625 for (ent = field;;) {
627 tarval *sz, *tv_index, *tlower, *tupper;
631 tp = get_entity_type(ent);
632 if (! is_Array_type(tp))
634 ent = get_array_element_entity(tp);
636 p[pos].next = &p[pos + 1];
638 size = get_type_size_bytes(get_entity_type(ent));
639 sz = new_tarval_from_long(size, mode);
641 tv_index = tarval_div(tv, sz);
642 tv = tarval_mod(tv, sz);
644 if (tv_index == tarval_bad || tv == tarval_bad)
647 assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
648 bound = get_array_lower_bound(tp, 0);
649 tlower = computed_value(bound);
650 bound = get_array_upper_bound(tp, 0);
651 tupper = computed_value(bound);
653 if (tlower == tarval_bad || tupper == tarval_bad)
656 if (tarval_cmp(tv_index, tlower) & pn_Cmp_Lt)
658 if (tarval_cmp(tupper, tv_index) & pn_Cmp_Lt)
661 /* ok, bounds check finished */
662 index = get_tarval_long(tv_index);
663 p[pos].index = index;
666 if (! tarval_is_null(tv)) {
667 /* hmm, wrong access */
670 p[pos - 1].next = next;
671 return rec_find_compound_ent_value(ptr, p);
672 } else if (is_Sub(ptr)) {
673 ir_node *l = get_Sub_left(ptr);
674 ir_node *r = get_Sub_right(ptr);
677 tv = get_Const_tarval(r);
684 static ir_node *find_compound_ent_value(ir_node *ptr) {
685 return rec_find_compound_ent_value(ptr, NULL);
689 static void reduce_adr_usage(ir_node *ptr);
692 * Update a Load that may have lost its users.
694 static void handle_load_update(ir_node *load) {
695 ldst_info_t *info = get_irn_link(load);
697 /* do NOT touch volatile loads for now */
698 if (get_Load_volatility(load) == volatility_is_volatile)
701 if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
702 ir_node *ptr = get_Load_ptr(load);
703 ir_node *mem = get_Load_mem(load);
705 /* a Load whose value is neither used nor exception checked, remove it */
706 exchange(info->projs[pn_Load_M], mem);
707 if (info->projs[pn_Load_X_regular])
708 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
710 reduce_adr_usage(ptr);
712 } /* handle_load_update */
715 * A use of an address node has vanished. Check if this was a Proj
716 * node and update the counters.
718 static void reduce_adr_usage(ir_node *ptr) {
720 if (get_irn_n_edges(ptr) <= 0) {
721 /* this Proj is dead now */
722 ir_node *pred = get_Proj_pred(ptr);
725 ldst_info_t *info = get_irn_link(pred);
726 info->projs[get_Proj_proj(ptr)] = NULL;
728 /* this node lost its result proj, handle that */
729 handle_load_update(pred);
733 } /* reduce_adr_usage */
736 * Check, if an already existing value of mode old_mode can be converted
737 * into the needed one new_mode without loss.
739 static int can_use_stored_value(ir_mode *old_mode, ir_mode *new_mode) {
740 if (old_mode == new_mode)
743 /* if both modes are two-complement ones, we can always convert the
744 Stored value into the needed one. */
745 if (get_mode_size_bits(old_mode) >= get_mode_size_bits(new_mode) &&
746 get_mode_arithmetic(old_mode) == irma_twos_complement &&
747 get_mode_arithmetic(new_mode) == irma_twos_complement)
750 } /* can_use_stored_value */
753 * Check whether a Call is at least pure, ie. does only read memory.
755 static unsigned is_Call_pure(ir_node *call) {
756 ir_type *call_tp = get_Call_type(call);
757 unsigned prop = get_method_additional_properties(call_tp);
759 /* check first the call type */
760 if ((prop & (mtp_property_const|mtp_property_pure)) == 0) {
761 /* try the called entity */
762 ir_node *ptr = get_Call_ptr(call);
764 if (is_Global(ptr)) {
765 ir_entity *ent = get_Global_entity(ptr);
767 prop = get_entity_additional_properties(ent);
770 return (prop & (mtp_property_const|mtp_property_pure)) != 0;
773 static ir_node *get_base_and_offset(ir_node *ptr, long *pOffset)
775 ir_mode *mode = get_irn_mode(ptr);
778 /* TODO: long might not be enough, we should probably use some tarval thingy... */
781 ir_node *l = get_Add_left(ptr);
782 ir_node *r = get_Add_right(ptr);
784 if (get_irn_mode(l) != mode || !is_Const(r))
787 offset += get_tarval_long(get_Const_tarval(r));
789 } else if (is_Sub(ptr)) {
790 ir_node *l = get_Sub_left(ptr);
791 ir_node *r = get_Sub_right(ptr);
793 if (get_irn_mode(l) != mode || !is_Const(r))
796 offset -= get_tarval_long(get_Const_tarval(r));
798 } else if (is_Sel(ptr)) {
799 ir_entity *ent = get_Sel_entity(ptr);
800 ir_type *tp = get_entity_owner(ent);
802 if (is_Array_type(tp)) {
806 /* only one dimensional arrays yet */
807 if (get_Sel_n_indexs(ptr) != 1)
809 index = get_Sel_index(ptr, 0);
810 if (! is_Const(index))
813 tp = get_entity_type(ent);
814 if (get_type_state(tp) != layout_fixed)
817 size = get_type_size_bytes(tp);
818 offset += size * get_tarval_long(get_Const_tarval(index));
820 if (get_type_state(tp) != layout_fixed)
822 offset += get_entity_offset(ent);
824 ptr = get_Sel_ptr(ptr);
833 static int try_load_after_store(ir_node *load,
834 ir_node *load_base_ptr, long load_offset, ir_node *store)
837 ir_node *store_ptr = get_Store_ptr(store);
839 ir_node *store_base_ptr = get_base_and_offset(store_ptr, &store_offset);
840 ir_node *store_value;
849 if (load_base_ptr != store_base_ptr)
852 load_mode = get_Load_mode(load);
853 load_mode_len = get_mode_size_bytes(load_mode);
854 store_mode = get_irn_mode(get_Store_value(store));
855 store_mode_len = get_mode_size_bytes(store_mode);
856 delta = load_offset - store_offset;
857 store_value = get_Store_value(store);
859 if (delta != 0 || store_mode != load_mode) {
860 if (delta < 0 || delta + load_mode_len > store_mode_len)
863 if (get_mode_arithmetic(store_mode) != irma_twos_complement ||
864 get_mode_arithmetic(load_mode) != irma_twos_complement)
868 /* produce a shift to adjust offset delta */
872 /* FIXME: only true for little endian */
873 cnst = new_Const_long(mode_Iu, delta * 8);
874 store_value = new_r_Shr(get_nodes_block(load),
875 store_value, cnst, store_mode);
878 /* add an convert if needed */
879 if (store_mode != load_mode) {
880 store_value = new_r_Conv(get_nodes_block(load), store_value, load_mode);
884 DBG_OPT_RAW(load, store_value);
886 info = get_irn_link(load);
887 if (info->projs[pn_Load_M])
888 exchange(info->projs[pn_Load_M], get_Load_mem(load));
892 if (info->projs[pn_Load_X_except]) {
893 exchange( info->projs[pn_Load_X_except], new_Bad());
896 if (info->projs[pn_Load_X_regular]) {
897 exchange( info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
901 if (info->projs[pn_Load_res])
902 exchange(info->projs[pn_Load_res], store_value);
904 load_ptr = get_Load_ptr(load);
906 reduce_adr_usage(load_ptr);
907 return res | DF_CHANGED;
911 * Follow the memory chain as long as there are only Loads,
912 * alias free Stores, and constant Calls and try to replace the
913 * current Load by a previous ones.
914 * Note that in unreachable loops it might happen that we reach
915 * load again, as well as we can fall into a cycle.
916 * We break such cycles using a special visited flag.
918 * INC_MASTER() must be called before dive into
920 static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
922 ldst_info_t *info = get_irn_link(load);
924 ir_node *ptr = get_Load_ptr(load);
925 ir_node *mem = get_Load_mem(load);
926 ir_mode *load_mode = get_Load_mode(load);
928 for (pred = curr; load != pred; ) {
929 ldst_info_t *pred_info = get_irn_link(pred);
932 * a Load immediately after a Store -- a read after write.
933 * We may remove the Load, if both Load & Store does not have an
934 * exception handler OR they are in the same MacroBlock. In the latter
935 * case the Load cannot throw an exception when the previous Store was
938 * Why we need to check for Store Exception? If the Store cannot
939 * be executed (ROM) the exception handler might simply jump into
940 * the load MacroBlock :-(
941 * We could make it a little bit better if we would know that the
942 * exception handler of the Store jumps directly to the end...
944 if (is_Store(pred) && ((pred_info->projs[pn_Store_X_except] == NULL
945 && info->projs[pn_Load_X_except] == NULL)
946 || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)))
949 ir_node *base_ptr = get_base_and_offset(ptr, &load_offset);
950 int changes = try_load_after_store(load, base_ptr, load_offset, pred);
953 return res | changes;
954 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
955 can_use_stored_value(get_Load_mode(pred), load_mode)) {
957 * a Load after a Load -- a read after read.
958 * We may remove the second Load, if it does not have an exception handler
959 * OR they are in the same MacroBlock. In the later case the Load cannot
960 * throw an exception when the previous Load was quiet.
962 * Here, there is no need to check if the previous Load has an exception
963 * hander because they would have exact the same exception...
965 if (info->projs[pn_Load_X_except] == NULL || get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)) {
968 DBG_OPT_RAR(load, pred);
970 /* the result is used */
971 if (info->projs[pn_Load_res]) {
972 if (pred_info->projs[pn_Load_res] == NULL) {
973 /* create a new Proj again */
974 pred_info->projs[pn_Load_res] = new_r_Proj(get_nodes_block(pred), pred, get_Load_mode(pred), pn_Load_res);
976 value = pred_info->projs[pn_Load_res];
978 /* add an convert if needed */
979 if (get_Load_mode(pred) != load_mode) {
980 value = new_r_Conv(get_nodes_block(load), value, load_mode);
983 exchange(info->projs[pn_Load_res], value);
986 if (info->projs[pn_Load_M])
987 exchange(info->projs[pn_Load_M], mem);
990 if (info->projs[pn_Load_X_except]) {
991 exchange(info->projs[pn_Load_X_except], new_Bad());
994 if (info->projs[pn_Load_X_regular]) {
995 exchange( info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1000 reduce_adr_usage(ptr);
1001 return res |= DF_CHANGED;
1005 if (is_Store(pred)) {
1006 /* check if we can pass through this store */
1007 ir_alias_relation rel = get_alias_relation(
1009 get_Store_ptr(pred),
1010 get_irn_mode(get_Store_value(pred)),
1012 /* if the might be an alias, we cannot pass this Store */
1013 if (rel != ir_no_alias)
1015 pred = skip_Proj(get_Store_mem(pred));
1016 } else if (is_Load(pred)) {
1017 pred = skip_Proj(get_Load_mem(pred));
1018 } else if (is_Call(pred)) {
1019 if (is_Call_pure(pred)) {
1020 /* The called graph is at least pure, so there are no Store's
1021 in it. We can handle it like a Load and skip it. */
1022 pred = skip_Proj(get_Call_mem(pred));
1024 /* there might be Store's in the graph, stop here */
1028 /* follow only Load chains */
1032 /* check for cycles */
1033 if (NODE_VISITED(pred_info))
1035 MARK_NODE(pred_info);
1038 if (is_Sync(pred)) {
1041 /* handle all Sync predecessors */
1042 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1043 res |= follow_Mem_chain(load, skip_Proj(get_Sync_pred(pred, i)));
1050 } /* follow_Mem_chain */
1053 * Check if we can replace the load by a given const from
1054 * the const code irg.
1056 ir_node *can_replace_load_by_const(const ir_node *load, ir_node *c) {
1057 ir_mode *c_mode = get_irn_mode(c);
1058 ir_mode *l_mode = get_Load_mode(load);
1059 ir_node *res = NULL;
1061 if (c_mode != l_mode) {
1062 /* check, if the mode matches OR can be easily converted info */
1063 if (is_reinterpret_cast(c_mode, l_mode)) {
1064 /* we can safely cast */
1065 dbg_info *dbg = get_irn_dbg_info(load);
1066 ir_node *block = get_nodes_block(load);
1068 /* copy the value from the const code irg and cast it */
1069 res = copy_const_value(dbg, c);
1070 res = new_rd_Conv(dbg, block, res, l_mode);
1073 /* copy the value from the const code irg */
1074 res = copy_const_value(get_irn_dbg_info(load), c);
1077 } /* can_replace_load_by_const */
1082 * @param load the Load node
1084 static unsigned optimize_load(ir_node *load)
1086 ldst_info_t *info = get_irn_link(load);
1087 ir_node *mem, *ptr, *value;
1092 /* do NOT touch volatile loads for now */
1093 if (get_Load_volatility(load) == volatility_is_volatile)
1096 /* the address of the load to be optimized */
1097 ptr = get_Load_ptr(load);
1100 * Check if we can remove the exception from a Load:
1101 * This can be done, if the address is from an Sel(Alloc) and
1102 * the Sel type is a subtype of the allocated type.
1104 * This optimizes some often used OO constructs,
1105 * like x = new O; x->t;
1107 if (info->projs[pn_Load_X_except]) {
1108 ir_node *addr = ptr;
1110 /* find base address */
1111 while (is_Sel(addr))
1112 addr = get_Sel_ptr(addr);
1113 if (is_Alloc(skip_Proj(skip_Cast(addr)))) {
1114 /* simple case: a direct load after an Alloc. Firm Alloc throw
1115 * an exception in case of out-of-memory. So, there is no way for an
1116 * exception in this load.
1117 * This code is constructed by the "exception lowering" in the Jack compiler.
1119 exchange(info->projs[pn_Load_X_except], new_Bad());
1120 info->projs[pn_Load_X_except] = NULL;
1121 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1122 info->projs[pn_Load_X_regular] = NULL;
1127 /* The mem of the Load. Must still be returned after optimization. */
1128 mem = get_Load_mem(load);
1130 if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
1131 /* a Load which value is neither used nor exception checked, remove it */
1132 exchange(info->projs[pn_Load_M], mem);
1134 if (info->projs[pn_Load_X_regular]) {
1135 /* should not happen, but if it does, remove it */
1136 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1140 reduce_adr_usage(ptr);
1141 return res | DF_CHANGED;
1144 /* Load from a constant polymorphic field, where we can resolve
1146 value = transform_polymorph_Load(load);
1147 if (value == load) {
1149 /* check if we can determine the entity that will be loaded */
1150 ent = find_constant_entity(ptr);
1152 allocation_static == get_entity_allocation(ent) &&
1153 visibility_external_allocated != get_entity_visibility(ent)) {
1154 /* a static allocation that is not external: there should be NO exception
1155 * when loading even if we cannot replace the load itself. */
1157 /* no exception, clear the info field as it might be checked later again */
1158 if (info->projs[pn_Load_X_except]) {
1159 exchange(info->projs[pn_Load_X_except], new_Bad());
1160 info->projs[pn_Load_X_except] = NULL;
1163 if (info->projs[pn_Load_X_regular]) {
1164 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1165 info->projs[pn_Load_X_regular] = NULL;
1169 if (variability_constant == get_entity_variability(ent)) {
1170 if (is_atomic_entity(ent)) {
1171 /* Might not be atomic after lowering of Sels. In this case we
1172 * could also load, but it's more complicated. */
1173 /* more simpler case: we load the content of a constant value:
1174 * replace it by the constant itself */
1175 value = get_atomic_ent_value(ent);
1176 } else if (ent->has_initializer) {
1177 /* new style initializer */
1178 value = find_compound_ent_value(ptr);
1180 /* old style initializer */
1181 compound_graph_path *path = get_accessed_path(ptr);
1184 assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));
1186 value = get_compound_ent_value_by_path(ent, path);
1187 DB((dbg, LEVEL_1, " Constant access at %F%F resulted in %+F\n", ent, path, value));
1188 free_compound_graph_path(path);
1192 value = can_replace_load_by_const(load, value);
1196 if (value != NULL) {
1197 /* we completely replace the load by this value */
1198 if (info->projs[pn_Load_X_except]) {
1199 exchange(info->projs[pn_Load_X_except], new_Bad());
1200 info->projs[pn_Load_X_except] = NULL;
1203 if (info->projs[pn_Load_X_regular]) {
1204 exchange(info->projs[pn_Load_X_regular], new_r_Jmp(get_nodes_block(load)));
1205 info->projs[pn_Load_X_regular] = NULL;
1208 if (info->projs[pn_Load_M]) {
1209 exchange(info->projs[pn_Load_M], mem);
1212 if (info->projs[pn_Load_res]) {
1213 exchange(info->projs[pn_Load_res], value);
1217 reduce_adr_usage(ptr);
1221 /* Check, if the address of this load is used more than once.
1222 * If not, more load cannot be removed in any case. */
1223 if (get_irn_n_uses(ptr) <= 1 && get_irn_n_uses(get_base_and_offset(ptr, &dummy)) <= 1)
1227 * follow the memory chain as long as there are only Loads
1228 * and try to replace current Load or Store by a previous one.
1229 * Note that in unreachable loops it might happen that we reach
1230 * load again, as well as we can fall into a cycle.
1231 * We break such cycles using a special visited flag.
1234 res = follow_Mem_chain(load, skip_Proj(mem));
1236 } /* optimize_load */
1239 * Check whether a value of mode new_mode would completely overwrite a value
1240 * of mode old_mode in memory.
1242 static int is_completely_overwritten(ir_mode *old_mode, ir_mode *new_mode)
1244 return get_mode_size_bits(new_mode) >= get_mode_size_bits(old_mode);
1245 } /* is_completely_overwritten */
1248 * Check whether small is a part of large (starting at same address).
1250 static int is_partially_same(ir_node *small, ir_node *large)
1252 ir_mode *sm = get_irn_mode(small);
1253 ir_mode *lm = get_irn_mode(large);
1255 /* FIXME: Check endianness */
1256 return is_Conv(small) && get_Conv_op(small) == large
1257 && get_mode_size_bytes(sm) < get_mode_size_bytes(lm)
1258 && get_mode_arithmetic(sm) == irma_twos_complement
1259 && get_mode_arithmetic(lm) == irma_twos_complement;
1260 } /* is_partially_same */
1263 * follow the memory chain as long as there are only Loads and alias free Stores.
1265 * INC_MASTER() must be called before dive into
1267 static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
1269 ldst_info_t *info = get_irn_link(store);
1271 ir_node *ptr = get_Store_ptr(store);
1272 ir_node *mem = get_Store_mem(store);
1273 ir_node *value = get_Store_value(store);
1274 ir_mode *mode = get_irn_mode(value);
1275 ir_node *block = get_nodes_block(store);
1276 ir_node *mblk = get_Block_MacroBlock(block);
1278 for (pred = curr; pred != store;) {
1279 ldst_info_t *pred_info = get_irn_link(pred);
1282 * BEWARE: one might think that checking the modes is useless, because
1283 * if the pointers are identical, they refer to the same object.
1284 * This is only true in strong typed languages, not is C were the following
1285 * is possible *(ir_type1 *)p = a; *(ir_type2 *)p = b ...
1286 * However, if the size of the mode that is written is bigger or equal the
1287 * size of the old one, the old value is completely overwritten and can be
1290 if (is_Store(pred) && get_Store_ptr(pred) == ptr &&
1291 get_nodes_MacroBlock(pred) == mblk) {
1293 * a Store after a Store in the same MacroBlock -- a write after write.
1297 * We may remove the first Store, if the old value is completely
1298 * overwritten or the old value is a part of the new value,
1299 * and if it does not have an exception handler.
1301 * TODO: What, if both have the same exception handler ???
1303 if (get_Store_volatility(pred) != volatility_is_volatile
1304 && !pred_info->projs[pn_Store_X_except]) {
1305 ir_node *predvalue = get_Store_value(pred);
1306 ir_mode *predmode = get_irn_mode(predvalue);
1308 if(is_completely_overwritten(predmode, mode)
1309 || is_partially_same(predvalue, value)) {
1310 DBG_OPT_WAW(pred, store);
1311 exchange(pred_info->projs[pn_Store_M], get_Store_mem(pred));
1313 reduce_adr_usage(ptr);
1319 * We may remove the Store, if the old value already contains
1320 * the new value, and if it does not have an exception handler.
1322 * TODO: What, if both have the same exception handler ???
1324 if (get_Store_volatility(store) != volatility_is_volatile
1325 && !info->projs[pn_Store_X_except]) {
1326 ir_node *predvalue = get_Store_value(pred);
1328 if(is_partially_same(value, predvalue)) {
1329 DBG_OPT_WAW(pred, store);
1330 exchange(info->projs[pn_Store_M], mem);
1332 reduce_adr_usage(ptr);
1336 } else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
1337 value == pred_info->projs[pn_Load_res]) {
1339 * a Store of a value just loaded from the same address
1340 * -- a write after read.
1341 * We may remove the Store, if it does not have an exception
1344 if (! info->projs[pn_Store_X_except]) {
1345 DBG_OPT_WAR(store, pred);
1346 exchange(info->projs[pn_Store_M], mem);
1348 reduce_adr_usage(ptr);
1353 if (is_Store(pred)) {
1354 /* check if we can pass through this store */
1355 ir_alias_relation rel = get_alias_relation(
1357 get_Store_ptr(pred),
1358 get_irn_mode(get_Store_value(pred)),
1360 /* if the might be an alias, we cannot pass this Store */
1361 if (rel != ir_no_alias)
1363 pred = skip_Proj(get_Store_mem(pred));
1364 } else if (is_Load(pred)) {
1365 ir_alias_relation rel = get_alias_relation(
1366 current_ir_graph, get_Load_ptr(pred), get_Load_mode(pred),
1368 if (rel != ir_no_alias)
1371 pred = skip_Proj(get_Load_mem(pred));
1373 /* follow only Load chains */
1377 /* check for cycles */
1378 if (NODE_VISITED(pred_info))
1380 MARK_NODE(pred_info);
1383 if (is_Sync(pred)) {
1386 /* handle all Sync predecessors */
1387 for (i = get_Sync_n_preds(pred) - 1; i >= 0; --i) {
1388 res |= follow_Mem_chain_for_Store(store, skip_Proj(get_Sync_pred(pred, i)));
1394 } /* follow_Mem_chain_for_Store */
1396 /** find entity used as base for an address calculation */
1397 static ir_entity *find_entity(ir_node *ptr)
1399 switch(get_irn_opcode(ptr)) {
1401 return get_SymConst_entity(ptr);
1403 ir_node *pred = get_Sel_ptr(ptr);
1404 if (get_irg_frame(get_irn_irg(ptr)) == pred)
1405 return get_Sel_entity(ptr);
1407 return find_entity(pred);
1411 ir_node *left = get_binop_left(ptr);
1413 if (mode_is_reference(get_irn_mode(left)))
1414 return find_entity(left);
1415 right = get_binop_right(ptr);
1416 if (mode_is_reference(get_irn_mode(right)))
1417 return find_entity(right);
1428 * @param store the Store node
1430 static unsigned optimize_store(ir_node *store) {
1435 if (get_Store_volatility(store) == volatility_is_volatile)
1438 ptr = get_Store_ptr(store);
1439 entity = find_entity(ptr);
1441 /* a store to an entity which is never read is unnecessary */
1442 if (entity != NULL && !(get_entity_usage(entity) & ir_usage_read)) {
1443 ldst_info_t *info = get_irn_link(store);
1444 if (info->projs[pn_Store_X_except] == NULL) {
1445 DB((dbg, LEVEL_1, " Killing useless %+F to never read entity %+F\n", store, entity));
1446 exchange(info->projs[pn_Store_M], get_Store_mem(store));
1448 reduce_adr_usage(ptr);
1453 /* Check, if the address of this Store is used more than once.
1454 * If not, this Store cannot be removed in any case. */
1455 if (get_irn_n_uses(ptr) <= 1)
1458 mem = get_Store_mem(store);
1460 /* follow the memory chain as long as there are only Loads */
1463 return follow_Mem_chain_for_Store(store, skip_Proj(mem));
1464 } /* optimize_store */
1467 * walker, optimizes Phi after Stores to identical places:
1468 * Does the following optimization:
1471 * val1 val2 val3 val1 val2 val3
1473 * Store Store Store \ | /
1480 * This reduces the number of stores and allows for predicated execution.
1481 * Moves Stores back to the end of a function which may be bad.
1483 * This is only possible if the predecessor blocks have only one successor.
1485 static unsigned optimize_phi(ir_node *phi, walk_env_t *wenv)
1488 ir_node *store, *old_store, *ptr, *block, *phi_block, *phiM, *phiD, *exc, *projM;
1490 ir_node **inM, **inD, **projMs;
1492 dbg_info *db = NULL;
1494 block_info_t *bl_info;
1497 /* Must be a memory Phi */
1498 if (get_irn_mode(phi) != mode_M)
1501 n = get_Phi_n_preds(phi);
1505 /* must be only one user */
1506 projM = get_Phi_pred(phi, 0);
1507 if (get_irn_n_edges(projM) != 1)
1510 store = skip_Proj(projM);
1512 if (!is_Store(store))
1515 block = get_nodes_block(store);
1517 /* abort on dead blocks */
1518 if (is_Block_dead(block))
1521 /* check if the block is post dominated by Phi-block
1522 and has no exception exit */
1523 bl_info = get_irn_link(block);
1524 if (bl_info->flags & BLOCK_HAS_EXC)
1527 phi_block = get_nodes_block(phi);
1528 if (! block_strictly_postdominates(phi_block, block))
1531 /* this is the address of the store */
1532 ptr = get_Store_ptr(store);
1533 mode = get_irn_mode(get_Store_value(store));
1534 info = get_irn_link(store);
1535 exc = info->exc_block;
1537 for (i = 1; i < n; ++i) {
1538 ir_node *pred = get_Phi_pred(phi, i);
1540 if (get_irn_n_edges(pred) != 1)
1543 pred = skip_Proj(pred);
1544 if (!is_Store(pred))
1547 if (ptr != get_Store_ptr(pred) || mode != get_irn_mode(get_Store_value(pred)))
1550 info = get_irn_link(pred);
1552 /* check, if all stores have the same exception flow */
1553 if (exc != info->exc_block)
1556 /* abort on dead blocks */
1557 block = get_nodes_block(pred);
1558 if (is_Block_dead(block))
1561 /* check if the block is post dominated by Phi-block
1562 and has no exception exit. Note that block must be different from
1563 Phi-block, else we would move a Store from end End of a block to its
1565 bl_info = get_irn_link(block);
1566 if (bl_info->flags & BLOCK_HAS_EXC)
1568 if (block == phi_block || ! block_postdominates(phi_block, block))
1573 * ok, when we are here, we found all predecessors of a Phi that
1574 * are Stores to the same address and size. That means whatever
1575 * we do before we enter the block of the Phi, we do a Store.
1576 * So, we can move the Store to the current block:
1578 * val1 val2 val3 val1 val2 val3
1580 * | Str | | Str | | Str | \ | /
1586 * Is only allowed if the predecessor blocks have only one successor.
1589 NEW_ARR_A(ir_node *, projMs, n);
1590 NEW_ARR_A(ir_node *, inM, n);
1591 NEW_ARR_A(ir_node *, inD, n);
1592 NEW_ARR_A(int, idx, n);
1594 /* Prepare: Collect all Store nodes. We must do this
1595 first because we otherwise may loose a store when exchanging its
1598 for (i = n - 1; i >= 0; --i) {
1601 projMs[i] = get_Phi_pred(phi, i);
1602 assert(is_Proj(projMs[i]));
1604 store = get_Proj_pred(projMs[i]);
1605 info = get_irn_link(store);
1607 inM[i] = get_Store_mem(store);
1608 inD[i] = get_Store_value(store);
1609 idx[i] = info->exc_idx;
1611 block = get_nodes_block(phi);
1613 /* second step: create a new memory Phi */
1614 phiM = new_rd_Phi(get_irn_dbg_info(phi), block, n, inM, mode_M);
1616 /* third step: create a new data Phi */
1617 phiD = new_rd_Phi(get_irn_dbg_info(phi), block, n, inD, mode);
1619 /* rewire memory and kill the node */
1620 for (i = n - 1; i >= 0; --i) {
1621 ir_node *proj = projMs[i];
1624 ir_node *store = get_Proj_pred(proj);
1625 exchange(proj, inM[i]);
1630 /* fourth step: create the Store */
1631 store = new_rd_Store(db, block, phiM, ptr, phiD, 0);
1633 co_set_irn_name(store, co_get_irn_ident(old_store));
1636 projM = new_rd_Proj(NULL, block, store, mode_M, pn_Store_M);
1638 info = get_ldst_info(store, &wenv->obst);
1639 info->projs[pn_Store_M] = projM;
1641 /* fifths step: repair exception flow */
1643 ir_node *projX = new_rd_Proj(NULL, block, store, mode_X, pn_Store_X_except);
1645 info->projs[pn_Store_X_except] = projX;
1646 info->exc_block = exc;
1647 info->exc_idx = idx[0];
1649 for (i = 0; i < n; ++i) {
1650 set_Block_cfgpred(exc, idx[i], projX);
1654 /* the exception block should be optimized as some inputs are identical now */
1660 /* sixth step: replace old Phi */
1661 exchange(phi, projM);
1663 return res | DF_CHANGED;
1664 } /* optimize_phi */
1667 * walker, do the optimizations
1669 static void do_load_store_optimize(ir_node *n, void *env) {
1670 walk_env_t *wenv = env;
1672 switch (get_irn_opcode(n)) {
1675 wenv->changes |= optimize_load(n);
1679 wenv->changes |= optimize_store(n);
1683 wenv->changes |= optimize_phi(n, wenv);
1689 } /* do_load_store_optimize */
1692 typedef struct scc {
1693 ir_node *head; /**< the head of the list */
1696 /** A node entry. */
1697 typedef struct node_entry {
1698 unsigned DFSnum; /**< the DFS number of this node */
1699 unsigned low; /**< the low number of this node */
1700 int in_stack; /**< flag, set if the node is on the stack */
1701 ir_node *next; /**< link to the next node the the same scc */
1702 scc *pscc; /**< the scc of this node */
1703 unsigned POnum; /**< the post order number for blocks */
1706 /** A loop entry. */
1707 typedef struct loop_env {
1708 ir_phase ph; /**< the phase object */
1709 ir_node **stack; /**< the node stack */
1710 int tos; /**< tos index */
1711 unsigned nextDFSnum; /**< the current DFS number */
1712 unsigned POnum; /**< current post order number */
1714 unsigned changes; /**< a bitmask of graph changes */
1718 * Gets the node_entry of a node
1720 static node_entry *get_irn_ne(ir_node *irn, loop_env *env) {
1721 ir_phase *ph = &env->ph;
1722 node_entry *e = phase_get_irn_data(&env->ph, irn);
1725 e = phase_alloc(ph, sizeof(*e));
1726 memset(e, 0, sizeof(*e));
1727 phase_set_irn_data(ph, irn, e);
1733 * Push a node onto the stack.
1735 * @param env the loop environment
1736 * @param n the node to push
1738 static void push(loop_env *env, ir_node *n) {
1741 if (env->tos == ARR_LEN(env->stack)) {
1742 int nlen = ARR_LEN(env->stack) * 2;
1743 ARR_RESIZE(ir_node *, env->stack, nlen);
1745 env->stack[env->tos++] = n;
1746 e = get_irn_ne(n, env);
1751 * pop a node from the stack
1753 * @param env the loop environment
1755 * @return The topmost node
1757 static ir_node *pop(loop_env *env) {
1758 ir_node *n = env->stack[--env->tos];
1759 node_entry *e = get_irn_ne(n, env);
1766 * Check if irn is a region constant.
1767 * The block or irn must strictly dominate the header block.
1769 * @param irn the node to check
1770 * @param header_block the header block of the induction variable
1772 static int is_rc(ir_node *irn, ir_node *header_block) {
1773 ir_node *block = get_nodes_block(irn);
1775 return (block != header_block) && block_dominates(block, header_block);
1778 typedef struct phi_entry phi_entry;
1780 ir_node *phi; /**< A phi with a region const memory. */
1781 int pos; /**< The position of the region const memory */
1782 ir_node *load; /**< the newly created load for this phi */
1787 * An entry in the avail set.
1789 typedef struct avail_entry_t {
1790 ir_node *ptr; /**< the address pointer */
1791 ir_mode *mode; /**< the load mode */
1792 ir_node *load; /**< the associated Load */
1796 * Compare two avail entries.
1798 static int cmp_avail_entry(const void *elt, const void *key, size_t size) {
1799 const avail_entry_t *a = elt;
1800 const avail_entry_t *b = key;
1803 return a->ptr != b->ptr || a->mode != b->mode;
1804 } /* cmp_avail_entry */
1807 * Calculate the hash value of an avail entry.
1809 static unsigned hash_cache_entry(const avail_entry_t *entry) {
1810 return get_irn_idx(entry->ptr) * 9 + HASH_PTR(entry->mode);
1811 } /* hash_cache_entry */
1814 * Move loops out of loops if possible.
1816 * @param pscc the loop described by an SCC
1817 * @param env the loop environment
1819 static void move_loads_out_of_loops(scc *pscc, loop_env *env) {
1820 ir_node *phi, *load, *next, *other, *next_other;
1823 phi_entry *phi_list = NULL;
1826 avail = new_set(cmp_avail_entry, 8);
1828 /* collect all outer memories */
1829 for (phi = pscc->head; phi != NULL; phi = next) {
1830 node_entry *ne = get_irn_ne(phi, env);
1833 /* check all memory Phi's */
1837 assert(get_irn_mode(phi) == mode_M && "DFS return non-memory Phi");
1839 for (j = get_irn_arity(phi) - 1; j >= 0; --j) {
1840 ir_node *pred = get_irn_n(phi, j);
1841 node_entry *pe = get_irn_ne(pred, env);
1843 if (pe->pscc != ne->pscc) {
1844 /* not in the same SCC, is region const */
1845 phi_entry *pe = phase_alloc(&env->ph, sizeof(*pe));
1849 pe->next = phi_list;
1854 /* no Phis no fun */
1855 assert(phi_list != NULL && "DFS found a loop without Phi");
1857 /* for now, we cannot handle more than one input (only reducible cf) */
1858 if (phi_list->next != NULL)
1861 for (load = pscc->head; load; load = next) {
1863 node_entry *ne = get_irn_ne(load, env);
1866 if (is_Load(load)) {
1867 ldst_info_t *info = get_irn_link(load);
1868 ir_node *ptr = get_Load_ptr(load);
1870 /* for now, we cannot handle Loads with exceptions */
1871 if (info->projs[pn_Load_res] == NULL || info->projs[pn_Load_X_regular] != NULL || info->projs[pn_Load_X_except] != NULL)
1874 /* for now, we can only move Load(Global) */
1875 if (! is_Global(ptr))
1877 ent = get_Global_entity(ptr);
1878 load_mode = get_Load_mode(load);
1879 for (other = pscc->head; other != NULL; other = next_other) {
1880 node_entry *ne = get_irn_ne(other, env);
1881 next_other = ne->next;
1883 if (is_Store(other)) {
1884 ir_alias_relation rel = get_alias_relation(
1886 get_Store_ptr(other),
1887 get_irn_mode(get_Store_value(other)),
1889 /* if the might be an alias, we cannot pass this Store */
1890 if (rel != ir_no_alias)
1893 /* only Phis and pure Calls are allowed here, so ignore them */
1895 if (other == NULL) {
1900 /* yep, no aliasing Store found, Load can be moved */
1901 DB((dbg, LEVEL_1, " Found a Load that could be moved: %+F\n", load));
1903 db = get_irn_dbg_info(load);
1904 for (pe = phi_list; pe != NULL; pe = pe->next) {
1906 ir_node *phi = pe->phi;
1907 ir_node *blk = get_nodes_block(phi);
1908 ir_node *pred = get_Block_cfgpred_block(blk, pos);
1910 avail_entry_t entry, *res;
1913 entry.mode = load_mode;
1914 res = set_find(avail, &entry, sizeof(entry), hash_cache_entry(&entry));
1918 irn = new_rd_Load(db, pred, get_Phi_pred(phi, pos), ptr, load_mode, 0);
1920 set_insert(avail, &entry, sizeof(entry), hash_cache_entry(&entry));
1921 DB((dbg, LEVEL_1, " Created %+F in %+F\n", irn, pred));
1924 ninfo = get_ldst_info(irn, phase_obst(&env->ph));
1926 ninfo->projs[pn_Load_M] = mem = new_r_Proj(pred, irn, mode_M, pn_Load_M);
1927 set_Phi_pred(phi, pos, mem);
1929 ninfo->projs[pn_Load_res] = new_r_Proj(pred, irn, load_mode, pn_Load_res);
1932 /* now kill the old Load */
1933 exchange(info->projs[pn_Load_M], get_Load_mem(load));
1934 exchange(info->projs[pn_Load_res], ninfo->projs[pn_Load_res]);
1936 env->changes |= DF_CHANGED;
1941 } /* move_loads_out_of_loops */
1944 * Process a loop SCC.
1946 * @param pscc the SCC
1947 * @param env the loop environment
1949 static void process_loop(scc *pscc, loop_env *env) {
1950 ir_node *irn, *next, *header = NULL;
1951 node_entry *b, *h = NULL;
1952 int j, only_phi, num_outside, process = 0;
1955 /* find the header block for this scc */
1956 for (irn = pscc->head; irn; irn = next) {
1957 node_entry *e = get_irn_ne(irn, env);
1958 ir_node *block = get_nodes_block(irn);
1961 b = get_irn_ne(block, env);
1963 if (header != NULL) {
1964 if (h->POnum < b->POnum) {
1974 /* check if this scc contains only Phi, Loads or Stores nodes */
1978 for (irn = pscc->head; irn; irn = next) {
1979 node_entry *e = get_irn_ne(irn, env);
1982 switch (get_irn_opcode(irn)) {
1984 if (is_Call_pure(irn)) {
1985 /* pure calls can be treated like loads */
1989 /* non-pure calls must be handle like may-alias Stores */
1992 /* cannot handle CopyB yet */
1996 if (get_Load_volatility(irn) == volatility_is_volatile) {
1997 /* cannot handle loops with volatile Loads */
2003 if (get_Store_volatility(irn) == volatility_is_volatile) {
2004 /* cannot handle loops with volatile Stores */
2013 for (j = get_irn_arity(irn) - 1; j >= 0; --j) {
2014 ir_node *pred = get_irn_n(irn, j);
2015 node_entry *pe = get_irn_ne(pred, env);
2017 if (pe->pscc != e->pscc) {
2018 /* not in the same SCC, must be a region const */
2019 if (! is_rc(pred, header)) {
2020 /* not a memory loop */
2023 if (out_rc == NULL) {
2024 /* first region constant */
2027 } else if (out_rc != pred) {
2028 /* another region constant */
2039 /* found a memory loop */
2040 DB((dbg, LEVEL_2, " Found a memory loop:\n "));
2041 if (only_phi && num_outside == 1) {
2042 /* a phi cycle with only one real predecessor can be collapsed */
2043 DB((dbg, LEVEL_2, " Found an USELESS Phi cycle:\n "));
2045 for (irn = pscc->head; irn; irn = next) {
2046 node_entry *e = get_irn_ne(irn, env);
2048 exchange(irn, out_rc);
2050 env->changes |= DF_CHANGED;
2054 #ifdef DEBUG_libfirm
2055 for (irn = pscc->head; irn; irn = next) {
2056 node_entry *e = get_irn_ne(irn, env);
2058 DB((dbg, LEVEL_2, " %+F,", irn));
2060 DB((dbg, LEVEL_2, "\n"));
2062 move_loads_out_of_loops(pscc, env);
2066 } /* process_loop */
2071 * @param pscc the SCC
2072 * @param env the loop environment
2074 static void process_scc(scc *pscc, loop_env *env) {
2075 ir_node *head = pscc->head;
2076 node_entry *e = get_irn_ne(head, env);
2078 #ifdef DEBUG_libfirm
2080 ir_node *irn, *next;
2082 DB((dbg, LEVEL_4, " SCC at %p:\n ", pscc));
2083 for (irn = pscc->head; irn; irn = next) {
2084 node_entry *e = get_irn_ne(irn, env);
2088 DB((dbg, LEVEL_4, " %+F,", irn));
2090 DB((dbg, LEVEL_4, "\n"));
2094 if (e->next != NULL) {
2095 /* this SCC has more than one member */
2096 process_loop(pscc, env);
2101 * Do Tarjan's SCC algorithm and drive load/store optimization.
2103 * @param irn start at this node
2104 * @param env the loop environment
2106 static void dfs(ir_node *irn, loop_env *env)
2109 node_entry *node = get_irn_ne(irn, env);
2111 mark_irn_visited(irn);
2113 node->DFSnum = env->nextDFSnum++;
2114 node->low = node->DFSnum;
2118 if (is_Phi(irn) || is_Sync(irn)) {
2119 n = get_irn_arity(irn);
2120 for (i = 0; i < n; ++i) {
2121 ir_node *pred = get_irn_n(irn, i);
2122 node_entry *o = get_irn_ne(pred, env);
2124 if (!irn_visited(pred)) {
2126 node->low = MIN(node->low, o->low);
2128 if (o->DFSnum < node->DFSnum && o->in_stack)
2129 node->low = MIN(o->DFSnum, node->low);
2131 } else if (is_fragile_op(irn)) {
2132 ir_node *pred = get_fragile_op_mem(irn);
2133 node_entry *o = get_irn_ne(pred, env);
2135 if (!irn_visited(pred)) {
2137 node->low = MIN(node->low, o->low);
2139 if (o->DFSnum < node->DFSnum && o->in_stack)
2140 node->low = MIN(o->DFSnum, node->low);
2141 } else if (is_Proj(irn)) {
2142 ir_node *pred = get_Proj_pred(irn);
2143 node_entry *o = get_irn_ne(pred, env);
2145 if (!irn_visited(pred)) {
2147 node->low = MIN(node->low, o->low);
2149 if (o->DFSnum < node->DFSnum && o->in_stack)
2150 node->low = MIN(o->DFSnum, node->low);
2153 /* IGNORE predecessors */
2156 if (node->low == node->DFSnum) {
2157 scc *pscc = phase_alloc(&env->ph, sizeof(*pscc));
2165 e = get_irn_ne(x, env);
2167 e->next = pscc->head;
2171 process_scc(pscc, env);
2176 * Do the DFS on the memory edges a graph.
2178 * @param irg the graph to process
2179 * @param env the loop environment
2181 static void do_dfs(ir_graph *irg, loop_env *env) {
2182 ir_graph *rem = current_ir_graph;
2183 ir_node *endblk, *end;
2186 current_ir_graph = irg;
2187 inc_irg_visited(irg);
2189 /* visit all memory nodes */
2190 endblk = get_irg_end_block(irg);
2191 for (i = get_Block_n_cfgpreds(endblk) - 1; i >= 0; --i) {
2192 ir_node *pred = get_Block_cfgpred(endblk, i);
2194 pred = skip_Proj(pred);
2195 if (is_Return(pred))
2196 dfs(get_Return_mem(pred), env);
2197 else if (is_Raise(pred))
2198 dfs(get_Raise_mem(pred), env);
2199 else if (is_fragile_op(pred))
2200 dfs(get_fragile_op_mem(pred), env);
2202 assert(0 && "Unknown EndBlock predecessor");
2206 /* visit the keep-alives */
2207 end = get_irg_end(irg);
2208 for (i = get_End_n_keepalives(end) - 1; i >= 0; --i) {
2209 ir_node *ka = get_End_keepalive(end, i);
2211 if (is_Phi(ka) && !irn_visited(ka))
2214 current_ir_graph = rem;
2218 * Initialize new phase data. We do this always explicit, so return NULL here
2220 static void *init_loop_data(ir_phase *ph, const ir_node *irn, void *data) {
2225 } /* init_loop_data */
2228 * Optimize Loads/Stores in loops.
2230 * @param irg the graph
2232 static int optimize_loops(ir_graph *irg) {
2235 env.stack = NEW_ARR_F(ir_node *, 128);
2240 phase_init(&env.ph, "ldstopt", irg, PHASE_DEFAULT_GROWTH, init_loop_data, NULL);
2242 /* calculate the SCC's and drive loop optimization. */
2245 DEL_ARR_F(env.stack);
2246 phase_free(&env.ph);
2249 } /* optimize_loops */
2252 * do the load store optimization
2254 int optimize_load_store(ir_graph *irg) {
2257 FIRM_DBG_REGISTER(dbg, "firm.opt.ldstopt");
2259 assert(get_irg_phase_state(irg) != phase_building);
2260 assert(get_irg_pinned(irg) != op_pin_state_floats &&
2261 "LoadStore optimization needs pinned graph");
2263 /* we need landing pads */
2264 remove_critical_cf_edges(irg);
2268 /* for Phi optimization post-dominators are needed ... */
2269 assure_postdoms(irg);
2271 if (get_opt_alias_analysis()) {
2272 assure_irg_entity_usage_computed(irg);
2273 assure_irp_globals_entity_usage_computed();
2276 obstack_init(&env.obst);
2279 /* init the links, then collect Loads/Stores/Proj's in lists */
2281 irg_walk_graph(irg, firm_clear_link, collect_nodes, &env);
2283 /* now we have collected enough information, optimize */
2284 irg_walk_graph(irg, NULL, do_load_store_optimize, &env);
2286 env.changes |= optimize_loops(irg);
2288 obstack_free(&env.obst, NULL);
2290 /* Handle graph state */
2292 set_irg_outs_inconsistent(irg);
2293 set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
2296 if (env.changes & CF_CHANGED) {
2297 /* is this really needed: Yes, control flow changed, block might
2298 have Bad() predecessors. */
2299 set_irg_doms_inconsistent(irg);
2301 return env.changes != 0;
2302 } /* optimize_load_store */
2304 ir_graph_pass_t *optimize_load_store_pass(const char *name, int verify, int dump)
2306 return def_graph_pass(name ? name : "ldst", verify, dump, optimize_load_store);
2307 } /* optimize_load_store_pass */