3 * File name: ir/opt/scalar_replace.c
4 * Purpose: scalar replacement of arrays and compounds
5 * Author: Beyhan Veliev
6 * Modified by: Michael Beck
9 * Copyright: (c) 1998-2005 Universität Karlsruhe
10 * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
28 #include "scalar_replace.h"
42 #define SET_VNUM(node, vnum) set_irn_link(node, INT_TO_PTR(vnum))
43 #define GET_VNUM(node) (unsigned)PTR_TO_INT(get_irn_link(node))
46 * A path element entry: it is either an entity
47 * or a tarval, because we evaluate only constant array
48 * accesses like a.b.c[8].d
56 * An access path, used to assign value numbers
57 * to variables that will be scalar replaced.
59 typedef struct _path_t {
60 unsigned vnum; /**< The value number. */
61 unsigned path_len; /**< The length of the access path. */
62 path_elem_t path[1]; /**< The path. */
65 /** The size of a path in bytes. */
66 #define PATH_SIZE(p) (sizeof(*(p)) + sizeof((p)->path[0]) * ((p)->path_len - 1))
68 typedef struct _scalars_t {
69 entity *ent; /**< A entity for scalar replacement. */
70 ir_type *ent_owner; /**< The owner of this entity. */
77 * @return 0 if they are identically
79 static int path_cmp(const void *elt, const void *key, size_t size)
81 const path_t *p1 = elt;
82 const path_t *p2 = key;
84 /* we can use memcmp here, because identical tarvals should have identical addresses */
85 return memcmp(p1->path, p2->path, p1->path_len * sizeof(p1->path[0]));
89 * Compare two elements of the scalars_t set.
91 * @return 0 if they are identically
93 static int ent_cmp(const void *elt, const void *key, size_t size)
95 const scalars_t *c1 = elt;
96 const scalars_t *c2 = key;
98 return c1->ent != c2->ent;
102 * Calculate a hash value for a path.
104 static unsigned path_hash(const path_t *path)
109 for (i = 0; i < path->path_len; ++i)
110 hash ^= (unsigned)PTR_TO_INT(path->path[i].ent);
116 * Returns non-zero, if all indeces of a Sel node are constants.
118 * @param sel the Sel node that will be checked
120 static int is_const_sel(ir_node *sel) {
121 int i, n = get_Sel_n_indexs(sel);
123 for (i = 0; i < n; ++i) {
124 ir_node *idx = get_Sel_index(sel, i);
126 if (get_irn_op(idx) != op_Const)
133 * Returns non-zero, if the address of an entity
134 * represented by a Sel node (or it's successor Sels) is taken.
136 int is_address_taken(ir_node *sel)
140 if (! is_const_sel(sel))
143 for (i = get_irn_n_outs(sel) - 1; i >= 0; --i) {
144 ir_node *succ = get_irn_out(sel, i);
146 switch (get_irn_opcode(succ)) {
148 /* ok, we just load from that entity */
152 /* check that Sel is not the Store's value */
153 if (get_Store_value(succ) == sel)
158 /* Check the Sel successor of Sel */
159 int res = is_address_taken(succ);
167 /* The address of an entity is given as a parameter.
168 * As long as we do not have analyses that can tell what
169 * is done with parameters, think is taken.
174 /* another op, the address is taken */
182 * Link all leave Sels with the entity.
184 * @param ent the entity that will be scalar replaced
185 * @param sel a Sel node that selects some fields of this entity
187 static void link_all_leave_sels(entity *ent, ir_node *sel)
191 n = get_irn_n_outs(sel);
192 for (i = 0; i < n; ++i) {
193 ir_node *succ = get_irn_out(sel, i);
196 link_all_leave_sels(ent, succ);
202 /* if Sel nodes with memory inputs are used, a entity can be
203 * visited more than once causing a ring here, so we use the
204 * node flag to mark linked nodes
206 if (irn_visited(sel))
209 /* we know we are at a leave, because this function is only
210 * called if the address is NOT taken, so succ must be a Load
213 set_irn_link(sel, get_entity_link(ent));
214 set_entity_link(ent, sel);
216 mark_irn_visited(sel);
220 /* we need a special address that serves as an address taken marker */
222 static void *ADDRESS_TAKEN = &_x;
225 * Find possible scalar replacements.
227 * @param irg an IR graph
229 * This function finds variables on the (members of the) frame type
230 * that can be scalar replaced, because their address is never taken.
231 * If such a variable is found, it's entity link will hold a list of all
232 * Sel nodes, that selects the atomic fields of this entity.
233 * Otherwise, the link will be ADDRESS_TAKEN or NULL.
235 * @return non-zero if at least one entity could be replaced
238 static int find_possible_replacements(ir_graph *irg)
240 ir_node *irg_frame = get_irg_frame(irg);
244 inc_irg_visited(irg);
246 n = get_irn_n_outs(irg_frame);
249 * First, clear the link field of all interesting entities.
250 * Note that we did not rely on the fact that there is only
251 * one Sel node per entity, so we might access one entity
252 * more than once here.
253 * That's why we have need two loops.
255 for (i = 0; i < n; ++i) {
256 ir_node *succ = get_irn_out(irg_frame, i);
259 entity *ent = get_Sel_entity(succ);
260 set_entity_link(ent, NULL);
265 * Check the ir_graph for Sel nodes. If the entity of Sel
266 * isn't a scalar replacement set the link of this entity
267 * equal ADDRESS_TAKEN.
269 for (i = 0; i < n; ++i) {
270 ir_node *succ = get_irn_out(irg_frame, i);
273 entity *ent = get_Sel_entity(succ);
276 if (get_entity_link(ent) == ADDRESS_TAKEN)
280 * Beware: in rare cases even entities on the frame might be
281 * volatile. This might happen if the entity serves as a store
282 * to a value that must survive a exception. Do not optimize
283 * such entities away.
285 if (get_entity_volatility(ent) == volatility_is_volatile) {
286 set_entity_link(ent, ADDRESS_TAKEN);
290 ent_type = get_entity_type(ent);
292 /* we can handle arrays, structs and atomic types yet */
293 if (is_Array_type(ent_type) || is_Struct_type(ent_type) || is_atomic_type(ent_type)) {
294 if (is_address_taken(succ)) {
295 if (get_entity_link(ent)) /* killing one */
297 set_entity_link(ent, ADDRESS_TAKEN);
300 /* possible found one */
301 if (get_entity_link(ent) == NULL)
303 link_all_leave_sels(ent, succ);
313 * Return a path from the Sel node sel to it's root.
315 * @param sel the Sel node
316 * @param len the length of the path so far
318 static path_t *find_path(ir_node *sel, unsigned len)
322 ir_node *pred = get_Sel_ptr(sel);
324 /* the current Sel node will add some path elements */
325 n = get_Sel_n_indexs(sel);
328 if (! is_Sel(pred)) {
329 /* we found the root */
331 res = xmalloc(sizeof(*res) + (len - 1) * sizeof(res->path));
335 res = find_path(pred, len);
337 pos = res->path_len - len;
339 res->path[pos++].ent = get_Sel_entity(sel);
340 for (i = 0; i < n; ++i) {
341 ir_node *index = get_Sel_index(sel, i);
343 res->path[pos++].tv = get_Const_tarval(index);
350 * Allocate value numbers for the leaves
351 * in our found entities.
353 * @param sels a set that will contain all Sels that have a value number
354 * @param ent the entity that will be scalar replaced
355 * @param vnum the first value number we can assign
356 * @param modes a flexible array, containing all the modes of
359 * @return the next free value number
361 static unsigned allocate_value_numbers(pset *sels, entity *ent, unsigned vnum, ir_mode ***modes)
365 set *pathes = new_set(path_cmp, 8);
367 /* visit all Sel nodes in the chain of the entity */
368 for (sel = get_entity_link(ent); sel; sel = next) {
369 next = get_irn_link(sel);
371 /* we must mark this sel for later */
372 pset_insert_ptr(sels, sel);
374 key = find_path(sel, 0);
375 path = set_find(pathes, key, PATH_SIZE(key), path_hash(key));
378 SET_VNUM(sel, path->vnum);
384 set_insert(pathes, key, PATH_SIZE(key), path_hash(key));
386 SET_VNUM(sel, key->vnum);
387 ARR_EXTO(ir_mode *, *modes, (key->vnum + 15) & ~15);
389 (*modes)[key->vnum] = get_type_mode(get_entity_type(get_Sel_entity(sel)));
391 assert((*modes)[key->vnum] && "Value is not atomic");
395 if (get_opt_scalar_replacement_verbose() && get_firm_verbosity() > 1) {
396 printf(" %s", get_entity_name(key->path[0].ent));
397 for (i = 1; i < key->path_len; ++i) {
398 if (is_entity(key->path[i].ent))
399 printf(".%s", get_entity_name(key->path[i].ent));
401 printf("[%ld]", get_tarval_long(key->path[i].tv));
403 printf(" = %u (%s)\n", PTR_TO_INT(get_irn_link(sel)), get_mode_name((*modes)[key->vnum]));
405 #endif /* DEBUG_libfirm */
411 set_entity_link(ent, NULL);
416 * A list entry for the fixing lists
418 typedef struct _list_entry_t {
419 ir_node *node; /**< the node that must be fixed */
420 unsigned vnum; /**< the value number of this node */
424 * environment for memory walker
426 typedef struct _env_t {
427 struct obstack obst; /**< a obstack for the value blocks */
428 int nvals; /**< number of values */
429 ir_mode **modes; /**< the modes of the values */
430 list_entry_t *fix_phis; /**< list of all Phi nodes that must be fixed */
431 list_entry_t *fix_loads; /**< list of all Load nodes that must be fixed */
432 pset *sels; /**< A set of all Sel nodes that have a value number */
436 * topological walker.
438 static void topologic_walker(ir_node *node, void *ctx)
441 ir_op *op = get_irn_op(node);
442 ir_node *adr, *block, *mem, *unk, **value_arr, **in, *val;
449 /* a load, check if we can resolve it */
450 adr = get_Load_ptr(node);
455 if (! pset_find_ptr(env->sels, adr))
458 /* ok, we have a Load that will be replaced */
459 vnum = GET_VNUM(adr);
461 assert(vnum < (unsigned)env->nvals);
463 block = get_nodes_block(node);
464 value_arr = get_irn_link(block);
466 /* check, if we can replace this Load */
467 if (value_arr[vnum]) {
468 mem = get_Load_mem(node);
470 /* Beware: A load can contain a hidden conversion in Firm.
471 This happens for instance in the following code:
474 unsigned j = *(unsigned *)&i;
477 val = value_arr[vnum];
478 mode = get_Load_mode(node);
479 if (mode != get_irn_mode(val))
480 val = new_d_Conv(get_irn_dbg_info(node), val, mode);
482 turn_into_tuple(node, pn_Load_max);
483 set_Tuple_pred(node, pn_Load_M, mem);
484 set_Tuple_pred(node, pn_Load_res, val);
485 set_Tuple_pred(node, pn_Load_X_except, new_Bad());
487 l = obstack_alloc(&env->obst, sizeof(*l));
491 set_irn_link(node, env->fix_loads);
494 } else if (op == op_Store) {
495 /* a Store always can be replaced */
496 adr = get_Store_ptr(node);
501 if (! pset_find_ptr(env->sels, adr))
504 vnum = GET_VNUM(adr);
506 assert(vnum < (unsigned)env->nvals);
508 block = get_nodes_block(node);
509 value_arr = get_irn_link(block);
511 value_arr[vnum] = get_Store_value(node);
513 mem = get_Store_mem(node);
515 turn_into_tuple(node, pn_Store_max);
516 set_Tuple_pred(node, pn_Store_M, mem);
517 set_Tuple_pred(node, pn_Store_X_except, new_Bad());
518 } else if (op == op_Phi && get_irn_mode(node) == mode_M) {
520 * found a memory Phi: Here, we must create new Phi nodes
522 block = get_nodes_block(node);
523 value_arr = get_irn_link(block);
525 n = get_Block_n_cfgpreds(block);
527 in = alloca(sizeof(*in) * n);
529 for (i = env->nvals - 1; i >= 0; --i) {
530 unk = new_Unknown(env->modes[i]);
531 for (j = n - 1; j >= 0; --j)
534 value_arr[i] = new_r_Phi(current_ir_graph, block, n, in, env->modes[i]);
536 l = obstack_alloc(&env->obst, sizeof(*l));
537 l->node = value_arr[i];
540 set_irn_link(value_arr[i], env->fix_phis);
547 * Walker: allocate the value array for every block.
549 static void alloc_value_arr(ir_node *block, void *ctx)
552 ir_node **var_arr = obstack_alloc(&env->obst, sizeof(*var_arr) * env->nvals);
554 /* the value array is empty at start */
555 memset(var_arr, 0, sizeof(*var_arr) * env->nvals);
556 set_irn_link(block, var_arr);
560 * searches through blocks beginning from block for value
561 * vnum and return it.
563 static ir_node *find_vnum_value(ir_node *block, unsigned vnum)
569 if (Block_not_block_visited(block)) {
570 mark_Block_block_visited(block);
572 value_arr = get_irn_link(block);
575 return value_arr[vnum];
577 for (i = get_Block_n_cfgpreds(block) - 1; i >= 0; --i) {
578 ir_node *pred = get_Block_cfgpred(block, i);
580 res = find_vnum_value(get_nodes_block(pred), vnum);
591 static void fix_phis(env_t *env)
594 ir_node *phi, *block, *pred, *val;
597 for (l = env->fix_phis; l; l = get_irn_link(phi)) {
600 block = get_nodes_block(phi);
601 for (i = get_irn_arity(phi) - 1; i >= 0; --i) {
602 pred = get_Block_cfgpred(block, i);
603 pred = get_nodes_block(pred);
605 inc_irg_block_visited(current_ir_graph);
606 val = find_vnum_value(pred, l->vnum);
609 set_irn_n(phi, i, val);
617 static void fix_loads(env_t *env)
620 ir_node *load, *block, *pred, *val = NULL, *mem;
624 for (l = env->fix_loads; l; l = get_irn_link(load)) {
627 block = get_nodes_block(load);
628 for (i = get_Block_n_cfgpreds(block) - 1; i >= 0; --i) {
629 pred = get_Block_cfgpred(block, i);
630 pred = get_nodes_block(pred);
632 inc_irg_block_visited(current_ir_graph);
633 val = find_vnum_value(pred, l->vnum);
640 /* access of an uninitialized value */
641 val = new_Unknown(env->modes[l->vnum]);
644 mem = get_Load_mem(load);
645 /* Beware: A load can contain a hidden conversion in Firm.
647 mode = get_Load_mode(load);
648 if (mode != get_irn_mode(val))
649 val = new_d_Conv(get_irn_dbg_info(load), val, mode);
651 turn_into_tuple(load, pn_Load_max);
652 set_Tuple_pred(load, pn_Load_M, mem);
653 set_Tuple_pred(load, pn_Load_res, val);
654 set_Tuple_pred(load, pn_Load_X_except, new_Bad());
659 * Make scalar replacement.
661 * @param sels A set containing all Sel nodes that have a value number
662 * @param nvals The number of scalars.
663 * @param modes A flexible array, containing all the modes of
666 static void do_scalar_replacements(pset *sels, int nvals, ir_mode **modes)
670 obstack_init(&env.obst);
674 env.fix_loads = NULL;
677 /* first step: allocate the value arrays for every block */
678 irg_block_walk_graph(current_ir_graph, NULL, alloc_value_arr, &env);
681 * second step: walk over the graph blockwise in topological order
682 * and fill the array as much as possible.
684 irg_walk_blkwise_graph(current_ir_graph, NULL, topologic_walker, &env);
686 /* third, fix the list of Phis, then the list of Loads */
690 obstack_free(&env.obst, NULL);
694 * Find possible scalar replacements
696 * @param irg The current ir graph.
698 void scalar_replacement_opt(ir_graph *irg)
702 scalars_t key, *value;
710 if (! get_opt_scalar_replacement())
713 rem = current_ir_graph;
715 /* Call algorithm that computes the out edges */
716 assure_irg_outs(irg);
718 /* Find possible scalar replacements */
719 if (find_possible_replacements(irg)) {
721 if (get_opt_scalar_replacement_verbose()) {
722 printf("Scalar Replacement: %s\n", get_entity_name(get_irg_entity(irg)));
725 /* Insert in set the scalar replacements. */
726 irg_frame = get_irg_frame(irg);
728 modes = NEW_ARR_F(ir_mode *, 16);
729 set_ent = new_set(ent_cmp, 8);
730 sels = pset_new_ptr(8);
732 for (i = 0 ; i < get_irn_n_outs(irg_frame); i++) {
733 ir_node *succ = get_irn_out(irg_frame, i);
736 entity *ent = get_Sel_entity(succ);
738 if (get_entity_link(ent) == NULL || get_entity_link(ent) == ADDRESS_TAKEN)
741 ent_type = get_entity_type(ent);
744 key.ent_owner = get_entity_owner(ent);
745 set_insert(set_ent, &key, sizeof(key), HASH_PTR(key.ent));
747 if (get_opt_scalar_replacement_verbose()) {
748 if (is_Array_type(ent_type)) {
749 printf(" found array %s\n", get_entity_name(ent));
751 else if (is_Struct_type(ent_type)) {
752 printf(" found struct %s\n", get_entity_name(ent));
754 else if (is_atomic_type(ent_type))
755 printf(" found atomic value %s\n", get_entity_name(ent));
757 assert(0 && "Neither an array nor a struct or atomic value");
761 nvals = allocate_value_numbers(sels, ent, nvals, &modes);
765 if (get_opt_scalar_replacement_verbose()) {
766 printf(" %u values will be needed\n", nvals);
769 /* If scalars were found. */
771 do_scalar_replacements(sels, nvals, modes);
773 for (value = set_first(set_ent); value; value = set_next(set_ent)) {
774 remove_class_member(value->ent_owner, value->ent);
784 * We changed the graph, but did NOT introduce new blocks
785 * neither changed control flow, cf-backedges should be still
788 set_irg_outs_inconsistent(irg);
789 set_irg_loopinfo_inconsistent(irg);
793 current_ir_graph = rem;