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
21 * @file ir/opt/ifconv.c
22 * @brief If conversion
23 * @author Christoph Mallon
33 #include "iroptimize.h"
50 DEBUG_ONLY(firm_dbg_module_t *dbg);
52 /** allow every Psi to be created. */
53 static int default_allow_ifconv(ir_node *sel, ir_node* phi_list, int i, int j)
61 static const opt_if_conv_info_t default_info = {
62 0, /* doesn't matter for Psi */
67 * Additional block info.
69 typedef struct block_info {
70 ir_node *phi; /**< head of the Phi list */
71 int has_pinned; /**< set if the block contains instructions that cannot be moved */
74 #define get_block_blockinfo(block) ((block_info *)get_irn_link(block))
77 * Returns non-zero if a Block can be emptied.
79 static int can_empty_block(ir_node *block)
81 return !get_block_blockinfo(block)->has_pinned;
85 static ir_node* walk_to_projx(ir_node* start, const ir_node* dependency)
90 /* No need to find the conditional block if this block cannot be emptied and
93 if (!can_empty_block(start)) return NULL;
95 arity = get_irn_arity(start);
96 for (i = 0; i < arity; ++i) {
97 ir_node* pred = get_irn_n(start, i);
98 ir_node* pred_block = get_nodes_block(pred);
100 if (pred_block == dependency) {
102 assert(get_irn_mode(pred) == mode_X);
109 assert(get_irn_mode(pred) == mode_X);
113 if (is_cdep_on(pred_block, dependency)) {
114 return walk_to_projx(pred_block, dependency);
122 * Copies the DAG starting at node to the ith predecessor block of src_block
123 * -if the node isn't in the src_block, this is a nop and the node is returned
124 * -if the node is a phi in the src_block, the ith predecessor of the phi is
126 * otherwise returns the copy of the passed node
128 static ir_node* copy_to(ir_node* node, ir_node* src_block, int i)
135 if (get_nodes_block(node) != src_block) return node;
136 if (get_irn_op(node) == op_Phi) return get_irn_n(node, i);
138 copy = exact_copy(node);
139 dst_block = get_nodes_block(get_irn_n(src_block, i));
140 set_nodes_block(copy, dst_block);
142 DB((dbg, LEVEL_1, "Copying node %+F to block %+F, copy is %+F\n",
143 node, dst_block, copy));
145 arity = get_irn_arity(node);
146 for (j = 0; j < arity; ++j) {
147 set_irn_n(copy, j, copy_to(get_irn_n(node, j), src_block, i));
148 DB((dbg, LEVEL_2, "-- pred %d is %+F\n", j, get_irn_n(copy, j)));
155 * Remove predecessors i and j from node and add predecessor new_pred
157 static void rewire(ir_node* node, int i, int j, ir_node* new_pred)
159 int arity = get_irn_arity(node);
164 NEW_ARR_A(ir_node *, ins, arity - 1);
167 for (k = 0; k < i; ++k) ins[l++] = get_irn_n(node, k);
168 for (++k; k < j; ++k) ins[l++] = get_irn_n(node, k);
169 for (++k; k < arity; ++k) ins[l++] = get_irn_n(node, k);
171 assert(l == arity - 1);
172 set_irn_in(node, l, ins);
177 * Remove the jth predecessors from the ith predecessor of block and add it to block
179 static void split_block(ir_node* block, int i, int j)
181 ir_node* pred_block = get_nodes_block(get_irn_n(block, i));
182 int arity = get_irn_arity(block);
189 DB((dbg, LEVEL_1, "Splitting predecessor %d of predecessor %d of %+F\n", j, i, block));
191 NEW_ARR_A(ir_node*, ins, arity + 1);
193 for (phi = get_block_blockinfo(block)->phi; phi != NULL; phi = get_irn_link(phi)) {
194 ir_node* copy = copy_to(get_irn_n(phi, i), pred_block, j);
196 for (k = 0; k < i; ++k) ins[k] = get_irn_n(phi, k);
198 for (; k < arity; ++k) ins[k] = get_irn_n(phi, k);
199 ins[k] = get_irn_n(phi, i);
201 set_irn_in(phi, arity + 1, ins);
204 for (k = 0; k < i; ++k) ins[k] = get_irn_n(block, k);
205 ins[k++] = get_irn_n(pred_block, j);
206 for (; k < arity; ++k) ins[k] = get_irn_n(block, k);
207 ins[k] = get_irn_n(block, i);
209 set_irn_in(block, arity + 1, ins);
211 new_pred_arity = get_irn_arity(pred_block) - 1;
212 NEW_ARR_A(ir_node*, pred_ins, new_pred_arity);
214 for (phi = get_block_blockinfo(pred_block)->phi; phi != NULL; phi = get_irn_link(phi)) {
215 for (k = 0; k < j; ++k) pred_ins[k] = get_irn_n(phi, k);
216 for (; k < new_pred_arity; ++k) pred_ins[k] = get_irn_n(phi, k + 1);
217 assert(k == new_pred_arity);
218 if (new_pred_arity > 1) {
219 set_irn_in(phi, new_pred_arity, pred_ins);
221 exchange(phi, pred_ins[0]);
225 for (k = 0; k < j; ++k) pred_ins[k] = get_irn_n(pred_block, k);
226 for (; k < new_pred_arity; ++k) pred_ins[k] = get_irn_n(pred_block, k + 1);
227 assert(k == new_pred_arity);
228 if (new_pred_arity > 1) {
229 set_irn_in(pred_block, new_pred_arity, pred_ins);
231 exchange(pred_block, get_nodes_block(pred_ins[0]));
236 static void prepare_path(ir_node* block, int i, const ir_node* dependency)
238 ir_node* pred = get_nodes_block(get_irn_n(block, i));
242 DB((dbg, LEVEL_1, "Preparing predecessor %d of %+F\n", i, block));
244 pred_arity = get_irn_arity(pred);
245 for (j = 0; j < pred_arity; ++j) {
246 ir_node* pred_pred = get_nodes_block(get_irn_n(pred, j));
248 if (is_cdep_on(pred_pred, dependency)) {
249 prepare_path(pred, j, dependency);
250 split_block(block, i, j);
257 static void if_conv_walker(ir_node* block, void* env)
261 opt_if_conv_info_t *opt_info = env;
263 /* Bail out, if there are no Phis at all */
264 if (get_block_blockinfo(block)->phi == NULL) return;
267 arity = get_irn_arity(block);
268 for (i = 0; i < arity; ++i) {
272 pred = get_nodes_block(get_irn_n(block, i));
273 for (cdep = find_cdep(pred); cdep != NULL; cdep = cdep->next) {
274 const ir_node* dependency = cdep->node;
275 ir_node* projx0 = walk_to_projx(pred, dependency);
279 if (projx0 == NULL) continue;
281 cond = get_Proj_pred(projx0);
282 if (get_irn_op(cond) != op_Cond) continue;
284 /* We only handle boolean decisions, no switches */
285 if (get_irn_mode(get_Cond_selector(cond)) != mode_b) continue;
287 for (j = i + 1; j < arity; ++j) {
295 pred = get_nodes_block(get_irn_n(block, j));
297 if (!is_cdep_on(pred, dependency)) continue;
299 projx1 = walk_to_projx(pred, dependency);
301 if (projx1 == NULL) continue;
303 phi = get_block_blockinfo(block)->phi;
304 if (!opt_info->allow_ifconv(get_Cond_selector(cond), phi, i, j)) continue;
306 DB((dbg, LEVEL_1, "Found Cond %+F with proj %+F and %+F\n",
310 prepare_path(block, i, dependency);
311 prepare_path(block, j, dependency);
312 arity = get_irn_arity(block);
314 conds[0] = get_Cond_selector(cond);
316 psi_block = get_nodes_block(cond);
318 ir_node* val_i = get_irn_n(phi, i);
319 ir_node* val_j = get_irn_n(phi, j);
321 if (val_i == val_j) {
323 DB((dbg, LEVEL_2, "Generating no psi, because both values are equal\n"));
325 /* Something is very fishy if two predecessors of a PhiM point into
326 * one block, but not at the same memory node
328 assert(get_irn_mode(phi) != mode_M);
329 if (get_Proj_proj(projx0) == pn_Cond_true) {
338 current_ir_graph, psi_block, 1, conds, vals, get_irn_mode(phi)
340 DB((dbg, LEVEL_2, "Generating %+F for %+F\n", psi, phi));
346 rewire(phi, i, j, psi);
349 phi = get_irn_link(phi);
350 } while (phi != NULL);
352 exchange(get_nodes_block(get_irn_n(block, i)), psi_block);
353 exchange(get_nodes_block(get_irn_n(block, j)), psi_block);
357 DB((dbg, LEVEL_1, "Welding block %+F and %+F\n", block, psi_block));
358 /* copy the block-info from the Psi-block to the block before merging */
359 get_block_blockinfo(psi_block)->has_pinned |= get_block_blockinfo(block)->has_pinned;
360 set_irn_link(block, get_irn_link(psi_block));
362 set_irn_in(block, get_irn_arity(psi_block), get_irn_in(psi_block) + 1);
363 exchange_cdep(psi_block, block);
364 exchange(psi_block, block);
366 DB((dbg, LEVEL_1, "Welding block %+F to %+F\n", block, psi_block));
367 get_block_blockinfo(psi_block)->has_pinned |= get_block_blockinfo(block)->has_pinned;
368 exchange(block, psi_block);
372 rewire(block, i, j, new_r_Jmp(current_ir_graph, psi_block));
381 * Block walker: add additional data
383 static void init_block_link(ir_node *block, void *env)
385 struct obstack *obst = env;
386 block_info *bi = obstack_alloc(obst, sizeof(*bi));
390 set_irn_link(block, bi);
395 * Daisy-chain all phis in a block
396 * If a non-movable node is encountered set the has_pinned flag
398 static void collect_phis(ir_node *node, void *env)
401 ir_node *block = get_nodes_block(node);
402 block_info *bi = get_block_blockinfo(block);
404 set_irn_link(node, bi->phi);
408 if (is_no_Block(node) && get_irn_pinned(node) == op_pin_state_pinned) {
410 * Ignore control flow nodes, these will be removed.
411 * This ignores Raise. That is surely bad. FIXME.
413 if (! is_cfop(node)) {
414 ir_node *block = get_nodes_block(node);
415 block_info *bi = get_block_blockinfo(block);
417 DB((dbg, LEVEL_2, "Node %+F in block %+F is unmovable\n", node, block));
426 * Transform multiple cascaded Psis into one Psi
428 static ir_node* fold_psi(ir_node* psi)
430 int arity = get_Psi_n_conds(psi);
441 for (i = 0; i < arity; ++i) {
442 n = get_Psi_val(psi, i);
443 if (get_irn_op(n) == op_Psi) {
444 new_arity += get_Psi_n_conds(n) + 1;
449 n = get_Psi_default(psi);
450 if (get_irn_op(n) == op_Psi) {
451 new_arity += get_Psi_n_conds(n);
454 if (arity == new_arity) return psi; // no attached Psis found
455 DB((dbg, LEVEL_1, "Folding %+F from %d to %d conds\n", psi, arity, new_arity));
457 NEW_ARR_A(ir_node *, conds, new_arity);
458 NEW_ARR_A(ir_node *, vals, new_arity + 1);
460 for (i = 0; i < arity; ++i) {
461 ir_node* c = get_Psi_cond(psi, i);
463 n = get_Psi_val(psi, i);
464 if (get_irn_op(n) == op_Psi) {
465 a = get_Psi_n_conds(n);
466 for (k = 0; k < a; ++k) {
467 conds[j] = new_r_And(
468 current_ir_graph, get_nodes_block(psi),
469 c, get_Psi_cond(n, k), mode_b
471 vals[j] = get_Psi_val(n, k);
475 vals[j] = get_Psi_default(n);
482 n = get_Psi_default(psi);
483 if (get_irn_op(n) == op_Psi) {
484 a = get_Psi_n_conds(n);
485 for (k = 0; k < a; ++k) {
486 conds[j] = get_Psi_cond(n, k);
487 vals[j] = get_Psi_val(n, k);
490 vals[j] = get_Psi_default(n);
494 assert(j == new_arity);
496 current_ir_graph, get_nodes_block(psi),
497 new_arity, conds, vals, get_irn_mode(psi)
499 DB((dbg, LEVEL_1, "Folded %+F into new %+F\n", psi, new_psi));
500 exchange(psi, new_psi);
506 * Merge consecutive psi inputs if the data inputs are the same
508 static ir_node* meld_psi(ir_node* psi)
510 int arity = get_Psi_n_conds(psi);
521 val = get_Psi_val(psi, 0);
522 DB((dbg, LEVEL_1, "Pred 0 of %+F is %+F\n", psi, val));
523 for (i = 1; i < arity; ++i) {
524 ir_node* v = get_Psi_val(psi, i);
525 DB((dbg, LEVEL_1, "Pred %2d of %+F is %+F\n", i, psi, v));
531 DB((dbg, LEVEL_1, "Default of %+F is %+F\n", psi, get_Psi_default(psi)));
532 if (val == get_Psi_default(psi)) --new_arity;
534 DB((dbg, LEVEL_1, "Melding Psi %+F from %d conds to %d\n", psi, arity, new_arity));
536 if (new_arity == arity) return psi;
538 /* If all data inputs of the Psi are equal, exchange the Psi with that value */
539 if (new_arity == 0) {
544 NEW_ARR_A(ir_node *, conds, new_arity);
545 NEW_ARR_A(ir_node *, vals, new_arity + 1);
546 cond = get_Psi_cond(psi, 0);
547 val = get_Psi_val(psi, 0);
549 for (i = 1; i < arity; ++i) {
550 ir_node* v = get_Psi_val(psi, i);
554 current_ir_graph, get_nodes_block(psi),
555 cond, get_Psi_cond(psi, i), mode_b
564 if (val != get_Psi_default(psi)) {
569 vals[j] = get_Psi_default(psi);
570 assert(j == new_arity);
572 current_ir_graph, get_nodes_block(psi),
573 new_arity, conds, vals, get_irn_mode(psi)
575 DB((dbg, LEVEL_1, "Molded %+F into %+F\n", psi, new_psi));
576 exchange(psi, new_psi);
582 * Split a Psi with multiple conditions into multiple Psis with one condtition
585 static ir_node* split_psi(ir_node* psi)
587 int arity = get_Psi_n_conds(psi);
593 if (arity == 1) return psi;
595 mode = get_irn_mode(psi);
596 block = get_nodes_block(psi);
597 rval = get_Psi_default(psi);
598 for (i = arity - 1; i >= 0; --i) {
602 conds[0] = get_Psi_cond(psi, i);
603 vals[0] = get_Psi_val(psi, i);
606 current_ir_graph, block, 1, conds, vals, mode
614 static void optimise_psis(ir_node* node, void* env)
616 if (get_irn_op(node) != op_Psi) return;
618 node = fold_psi(node);
621 node = meld_psi(node);
624 node = split_psi(node);
629 void opt_if_conv(ir_graph *irg, const opt_if_conv_info_t *params)
632 opt_if_conv_info_t p;
634 if (! get_opt_if_conversion())
637 /* get the parameters */
638 p = (params != NULL ? *params : default_info);
640 FIRM_DBG_REGISTER(dbg, "firm.opt.ifconv");
642 DB((dbg, LEVEL_1, "Running if-conversion on %+F\n", irg));
644 normalize_one_return(irg);
645 remove_critical_cf_edges(irg);
651 irg_block_walk_graph(irg, init_block_link, NULL, &obst);
652 irg_walk_graph(irg, collect_phis, NULL, NULL);
653 irg_block_walk_graph(irg, NULL, if_conv_walker, &p);
655 local_optimize_graph(irg);
657 irg_walk_graph(irg, NULL, optimise_psis, NULL);
659 obstack_free(&obst, NULL);