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)
65 static const opt_if_conv_info_t default_info = {
66 0, /* doesn't matter for Psi */
71 * Additional block info.
73 typedef struct block_info {
74 ir_node *phi; /**< head of the Phi list */
75 int has_pinned; /**< set if the block contains instructions that cannot be moved */
78 #define get_block_blockinfo(block) ((block_info *)get_irn_link(block))
81 * Returns non-zero if a Block can be emptied.
83 static int can_empty_block(ir_node *block)
85 return !get_block_blockinfo(block)->has_pinned;
89 static ir_node* walk_to_projx(ir_node* start, const ir_node* dependency)
94 /* No need to find the conditional block if this block cannot be emptied and
97 if (!can_empty_block(start)) return NULL;
99 arity = get_irn_arity(start);
100 for (i = 0; i < arity; ++i) {
101 ir_node* pred = get_irn_n(start, i);
102 ir_node* pred_block = get_nodes_block(pred);
104 if (pred_block == dependency) {
106 assert(get_irn_mode(pred) == mode_X);
113 assert(get_irn_mode(pred) == mode_X);
117 if (is_cdep_on(pred_block, dependency)) {
118 return walk_to_projx(pred_block, dependency);
126 * Copies the DAG starting at node to the ith predecessor block of src_block
127 * -if the node isn't in the src_block, this is a nop and the node is returned
128 * -if the node is a phi in the src_block, the ith predecessor of the phi is
130 * otherwise returns the copy of the passed node
132 static ir_node* copy_to(ir_node* node, ir_node* src_block, int i)
139 if (get_nodes_block(node) != src_block) return node;
140 if (get_irn_op(node) == op_Phi) return get_irn_n(node, i);
142 copy = exact_copy(node);
143 dst_block = get_nodes_block(get_irn_n(src_block, i));
144 set_nodes_block(copy, dst_block);
146 DB((dbg, LEVEL_1, "Copying node %+F to block %+F, copy is %+F\n",
147 node, dst_block, copy));
149 arity = get_irn_arity(node);
150 for (j = 0; j < arity; ++j) {
151 set_irn_n(copy, j, copy_to(get_irn_n(node, j), src_block, i));
152 DB((dbg, LEVEL_2, "-- pred %d is %+F\n", j, get_irn_n(copy, j)));
159 * Remove predecessors i and j from node and add predecessor new_pred
161 static void rewire(ir_node* node, int i, int j, ir_node* new_pred)
163 int arity = get_irn_arity(node);
168 NEW_ARR_A(ir_node *, ins, arity - 1);
171 for (k = 0; k < i; ++k) ins[l++] = get_irn_n(node, k);
172 for (++k; k < j; ++k) ins[l++] = get_irn_n(node, k);
173 for (++k; k < arity; ++k) ins[l++] = get_irn_n(node, k);
175 assert(l == arity - 1);
176 set_irn_in(node, l, ins);
181 * Remove the jth predecessors from the ith predecessor of block and add it to block
183 static void split_block(ir_node* block, int i, int j)
185 ir_node* pred_block = get_nodes_block(get_irn_n(block, i));
186 int arity = get_irn_arity(block);
193 DB((dbg, LEVEL_1, "Splitting predecessor %d of predecessor %d of %+F\n", j, i, block));
195 NEW_ARR_A(ir_node*, ins, arity + 1);
197 for (phi = get_block_blockinfo(block)->phi; phi != NULL; phi = get_irn_link(phi)) {
198 ir_node* copy = copy_to(get_irn_n(phi, i), pred_block, j);
200 for (k = 0; k < i; ++k) ins[k] = get_irn_n(phi, k);
202 for (; k < arity; ++k) ins[k] = get_irn_n(phi, k);
203 ins[k] = get_irn_n(phi, i);
205 set_irn_in(phi, arity + 1, ins);
208 for (k = 0; k < i; ++k) ins[k] = get_irn_n(block, k);
209 ins[k++] = get_irn_n(pred_block, j);
210 for (; k < arity; ++k) ins[k] = get_irn_n(block, k);
211 ins[k] = get_irn_n(block, i);
213 set_irn_in(block, arity + 1, ins);
215 new_pred_arity = get_irn_arity(pred_block) - 1;
216 NEW_ARR_A(ir_node*, pred_ins, new_pred_arity);
218 for (phi = get_block_blockinfo(pred_block)->phi; phi != NULL; phi = get_irn_link(phi)) {
219 for (k = 0; k < j; ++k) pred_ins[k] = get_irn_n(phi, k);
220 for (; k < new_pred_arity; ++k) pred_ins[k] = get_irn_n(phi, k + 1);
221 assert(k == new_pred_arity);
222 if (new_pred_arity > 1) {
223 set_irn_in(phi, new_pred_arity, pred_ins);
225 exchange(phi, pred_ins[0]);
229 for (k = 0; k < j; ++k) pred_ins[k] = get_irn_n(pred_block, k);
230 for (; k < new_pred_arity; ++k) pred_ins[k] = get_irn_n(pred_block, k + 1);
231 assert(k == new_pred_arity);
232 if (new_pred_arity > 1) {
233 set_irn_in(pred_block, new_pred_arity, pred_ins);
235 exchange(pred_block, get_nodes_block(pred_ins[0]));
240 static void prepare_path(ir_node* block, int i, const ir_node* dependency)
242 ir_node* pred = get_nodes_block(get_irn_n(block, i));
246 DB((dbg, LEVEL_1, "Preparing predecessor %d of %+F\n", i, block));
248 pred_arity = get_irn_arity(pred);
249 for (j = 0; j < pred_arity; ++j) {
250 ir_node* pred_pred = get_nodes_block(get_irn_n(pred, j));
252 if (is_cdep_on(pred_pred, dependency)) {
253 prepare_path(pred, j, dependency);
254 split_block(block, i, j);
261 static void if_conv_walker(ir_node* block, void* env)
265 opt_if_conv_info_t *opt_info = env;
267 /* Bail out, if there are no Phis at all */
268 if (get_block_blockinfo(block)->phi == NULL) return;
271 arity = get_irn_arity(block);
272 for (i = 0; i < arity; ++i) {
276 pred = get_nodes_block(get_irn_n(block, i));
277 for (cdep = find_cdep(pred); cdep != NULL; cdep = cdep->next) {
278 const ir_node* dependency = cdep->node;
279 ir_node* projx0 = walk_to_projx(pred, dependency);
283 if (projx0 == NULL) continue;
285 cond = get_Proj_pred(projx0);
286 if (get_irn_op(cond) != op_Cond) continue;
288 /* We only handle boolean decisions, no switches */
289 if (get_irn_mode(get_Cond_selector(cond)) != mode_b) continue;
291 for (j = i + 1; j < arity; ++j) {
299 pred = get_nodes_block(get_irn_n(block, j));
301 if (!is_cdep_on(pred, dependency)) continue;
303 projx1 = walk_to_projx(pred, dependency);
305 if (projx1 == NULL) continue;
307 phi = get_block_blockinfo(block)->phi;
308 if (!opt_info->allow_ifconv(get_Cond_selector(cond), phi, i, j)) continue;
310 DB((dbg, LEVEL_1, "Found Cond %+F with proj %+F and %+F\n",
314 prepare_path(block, i, dependency);
315 prepare_path(block, j, dependency);
316 arity = get_irn_arity(block);
318 conds[0] = get_Cond_selector(cond);
320 psi_block = get_nodes_block(cond);
322 ir_node* val_i = get_irn_n(phi, i);
323 ir_node* val_j = get_irn_n(phi, j);
325 if (val_i == val_j) {
327 DB((dbg, LEVEL_2, "Generating no psi, because both values are equal\n"));
329 /* Something is very fishy if two predecessors of a PhiM point into
330 * one block, but not at the same memory node
332 assert(get_irn_mode(phi) != mode_M);
333 if (get_Proj_proj(projx0) == pn_Cond_true) {
342 current_ir_graph, psi_block, 1, conds, vals, get_irn_mode(phi)
344 DB((dbg, LEVEL_2, "Generating %+F for %+F\n", psi, phi));
350 rewire(phi, i, j, psi);
353 phi = get_irn_link(phi);
354 } while (phi != NULL);
356 exchange(get_nodes_block(get_irn_n(block, i)), psi_block);
357 exchange(get_nodes_block(get_irn_n(block, j)), psi_block);
361 DB((dbg, LEVEL_1, "Welding block %+F and %+F\n", block, psi_block));
362 /* copy the block-info from the Psi-block to the block before merging */
363 get_block_blockinfo(psi_block)->has_pinned |= get_block_blockinfo(block)->has_pinned;
364 set_irn_link(block, get_irn_link(psi_block));
366 set_irn_in(block, get_irn_arity(psi_block), get_irn_in(psi_block) + 1);
367 exchange_cdep(psi_block, block);
368 exchange(psi_block, block);
370 DB((dbg, LEVEL_1, "Welding block %+F to %+F\n", block, psi_block));
371 get_block_blockinfo(psi_block)->has_pinned |= get_block_blockinfo(block)->has_pinned;
372 exchange(block, psi_block);
376 rewire(block, i, j, new_r_Jmp(current_ir_graph, psi_block));
385 * Block walker: add additional data
387 static void init_block_link(ir_node *block, void *env)
389 struct obstack *obst = env;
390 block_info *bi = obstack_alloc(obst, sizeof(*bi));
394 set_irn_link(block, bi);
399 * Daisy-chain all phis in a block
400 * If a non-movable node is encountered set the has_pinned flag
402 static void collect_phis(ir_node *node, void *env)
407 ir_node *block = get_nodes_block(node);
408 block_info *bi = get_block_blockinfo(block);
410 set_irn_link(node, bi->phi);
414 if (is_no_Block(node) && get_irn_pinned(node) == op_pin_state_pinned) {
416 * Ignore control flow nodes, these will be removed.
417 * This ignores Raise. That is surely bad. FIXME.
419 if (! is_cfop(node)) {
420 ir_node *block = get_nodes_block(node);
421 block_info *bi = get_block_blockinfo(block);
423 DB((dbg, LEVEL_2, "Node %+F in block %+F is unmovable\n", node, block));
432 * Transform multiple cascaded Psis into one Psi
434 static ir_node* fold_psi(ir_node* psi)
436 int arity = get_Psi_n_conds(psi);
447 for (i = 0; i < arity; ++i) {
448 n = get_Psi_val(psi, i);
449 if (get_irn_op(n) == op_Psi) {
450 new_arity += get_Psi_n_conds(n) + 1;
455 n = get_Psi_default(psi);
456 if (get_irn_op(n) == op_Psi) {
457 new_arity += get_Psi_n_conds(n);
460 if (arity == new_arity) return psi; // no attached Psis found
461 DB((dbg, LEVEL_1, "Folding %+F from %d to %d conds\n", psi, arity, new_arity));
463 NEW_ARR_A(ir_node *, conds, new_arity);
464 NEW_ARR_A(ir_node *, vals, new_arity + 1);
466 for (i = 0; i < arity; ++i) {
467 ir_node* c = get_Psi_cond(psi, i);
469 n = get_Psi_val(psi, i);
470 if (get_irn_op(n) == op_Psi) {
471 a = get_Psi_n_conds(n);
472 for (k = 0; k < a; ++k) {
473 conds[j] = new_r_And(
474 current_ir_graph, get_nodes_block(psi),
475 c, get_Psi_cond(n, k), mode_b
477 vals[j] = get_Psi_val(n, k);
481 vals[j] = get_Psi_default(n);
488 n = get_Psi_default(psi);
489 if (get_irn_op(n) == op_Psi) {
490 a = get_Psi_n_conds(n);
491 for (k = 0; k < a; ++k) {
492 conds[j] = get_Psi_cond(n, k);
493 vals[j] = get_Psi_val(n, k);
496 vals[j] = get_Psi_default(n);
500 assert(j == new_arity);
502 current_ir_graph, get_nodes_block(psi),
503 new_arity, conds, vals, get_irn_mode(psi)
505 DB((dbg, LEVEL_1, "Folded %+F into new %+F\n", psi, new_psi));
506 exchange(psi, new_psi);
512 * Merge consecutive psi inputs if the data inputs are the same
514 static ir_node* meld_psi(ir_node* psi)
516 int arity = get_Psi_n_conds(psi);
527 val = get_Psi_val(psi, 0);
528 DB((dbg, LEVEL_1, "Pred 0 of %+F is %+F\n", psi, val));
529 for (i = 1; i < arity; ++i) {
530 ir_node* v = get_Psi_val(psi, i);
531 DB((dbg, LEVEL_1, "Pred %2d of %+F is %+F\n", i, psi, v));
537 DB((dbg, LEVEL_1, "Default of %+F is %+F\n", psi, get_Psi_default(psi)));
538 if (val == get_Psi_default(psi)) --new_arity;
540 DB((dbg, LEVEL_1, "Melding Psi %+F from %d conds to %d\n", psi, arity, new_arity));
542 if (new_arity == arity) return psi;
544 /* If all data inputs of the Psi are equal, exchange the Psi with that value */
545 if (new_arity == 0) {
550 NEW_ARR_A(ir_node *, conds, new_arity);
551 NEW_ARR_A(ir_node *, vals, new_arity + 1);
552 cond = get_Psi_cond(psi, 0);
553 val = get_Psi_val(psi, 0);
555 for (i = 1; i < arity; ++i) {
556 ir_node* v = get_Psi_val(psi, i);
560 current_ir_graph, get_nodes_block(psi),
561 cond, get_Psi_cond(psi, i), mode_b
570 if (val != get_Psi_default(psi)) {
575 vals[j] = get_Psi_default(psi);
576 assert(j == new_arity);
578 current_ir_graph, get_nodes_block(psi),
579 new_arity, conds, vals, get_irn_mode(psi)
581 DB((dbg, LEVEL_1, "Molded %+F into %+F\n", psi, new_psi));
582 exchange(psi, new_psi);
588 * Split a Psi with multiple conditions into multiple Psis with one condtition
591 static ir_node* split_psi(ir_node* psi)
593 int arity = get_Psi_n_conds(psi);
599 if (arity == 1) return psi;
601 mode = get_irn_mode(psi);
602 block = get_nodes_block(psi);
603 rval = get_Psi_default(psi);
604 for (i = arity - 1; i >= 0; --i) {
608 conds[0] = get_Psi_cond(psi, i);
609 vals[0] = get_Psi_val(psi, i);
612 current_ir_graph, block, 1, conds, vals, mode
620 static void optimise_psis(ir_node* node, void* env)
624 if (get_irn_op(node) != op_Psi) return;
626 node = fold_psi(node);
629 node = meld_psi(node);
632 node = split_psi(node);
637 void opt_if_conv(ir_graph *irg, const opt_if_conv_info_t *params)
640 opt_if_conv_info_t p;
642 if (! get_opt_if_conversion())
645 /* get the parameters */
646 p = (params != NULL ? *params : default_info);
648 FIRM_DBG_REGISTER(dbg, "firm.opt.ifconv");
650 DB((dbg, LEVEL_1, "Running if-conversion on %+F\n", irg));
652 normalize_one_return(irg);
653 remove_critical_cf_edges(irg);
659 irg_block_walk_graph(irg, init_block_link, NULL, &obst);
660 irg_walk_graph(irg, collect_phis, NULL, NULL);
661 irg_block_walk_graph(irg, NULL, if_conv_walker, &p);
663 local_optimize_graph(irg);
665 irg_walk_graph(irg, NULL, optimise_psis, NULL);
667 obstack_free(&obst, NULL);