6 * File name: ir/opt/strength_red.c
7 * Purpose: Make strength reduction .
8 * Author: Beyhan Veliev
12 * Copyright: (c) 2004 Universität Karlsruhe
13 * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
24 reduce_itervar(induct_var_info *iv)
25 for each (out o of iv) {
27 if (o is strong (Mul))
28 iv_new = reduce(o), remember_pattern(o)
29 else // o is not strong (Add ...)
30 if (o is the only user)
37 # include "strength_red.h"
40 # include "irnode_t.h"
42 # include "irloop_t.h"
46 # include "firmstat.h"
49 /* The information needed for an induction variable */
50 typedef struct _induct_var_info {
51 ir_op *operation_code;
52 ir_node *increment, *init, *op, *itervar_phi, *c, *new_phi, *new_increment, *new_init;
53 ir_node *new_op, *new_add, *reducible_node;
54 ir_node *old_ind, *symconst, *new_cmp, *cmp_const, *cmp_init_block, *cmp;
55 ir_loop *l_itervar_phi;
56 int be_pos, strong_reduced;
57 int init_pred_pos, op_pred_pos, out_loop_res, phi_pred, reducible;
63 /** Counter for verbose information about optimization. */
64 static int n_reduced_expressions;
65 static int n_made_new_phis;
66 /** Detect basic iteration variables.
68 * The variable ir represented by a subgraph as this:
78 * Where op is a Add or Sub, and init is loop invariant.
79 * @@@ So far we only accept Phi nodes with two predecessors.
80 * We could expand this to Phi nodes where all preds are either
81 * op or loop invariant.
83 * @param n A phi node.
84 * @param info After call contains the induction variable information
86 static induct_var_info *is_induction_variable (induct_var_info *info) {
88 ir_node *phi_pred_0, *phi_pred_1, *add_r, *add_l, *sub_r, *sub_l ;
89 ir_op *phi_pred_0_op, *phi_pred_1_op;
93 info->cmp_const = NULL;
94 info->cmp_init_block = NULL;
95 info->increment = NULL;
97 info->l_itervar_phi = NULL;
100 info->new_increment = NULL;
101 info->new_init = NULL;
103 info->new_phi = NULL;
104 info->operation_code = NULL;
106 info->old_ind = NULL;
107 info->reducible_node = NULL;
108 info->out_loop_res = 1;
111 info->strong_reduced = 0;
113 info->init_pred_pos = -1;
114 info->op_pred_pos = -1;
116 assert(get_irn_op(info->itervar_phi) == op_Phi);
118 /* The necessary conditions for the phi node. */
119 if (get_irn_arity(info->itervar_phi) != 2 ||
120 !has_backedges(get_nodes_block(info->itervar_phi)) )
123 /* The predecessors of the phi node. */
124 phi_pred_0 = get_Phi_pred(info->itervar_phi, 0);
125 phi_pred_1 = get_Phi_pred(info->itervar_phi, 1);
127 /*The operation of the predecessors. */
128 phi_pred_0_op = get_irn_op(phi_pred_0);
129 phi_pred_1_op = get_irn_op(phi_pred_1);
131 /*Compute if the induction variable is added or substracted wiht a constant . */
132 if (phi_pred_0_op == op_Add){
133 info->operation_code = op_Add;
134 add_l = get_Add_left(phi_pred_0);
135 add_r = get_Add_right(phi_pred_0);
136 info->op_pred_pos = 0;
137 info->init_pred_pos = 1;
138 if (add_l == info->itervar_phi){
139 info->increment = add_r;
140 } else if (add_r == info->itervar_phi){
141 info->increment = add_l;
143 } else if (phi_pred_1_op == op_Add){
144 info->operation_code = op_Add ;
145 add_l = get_Add_left(phi_pred_1);
146 add_r = get_Add_right(phi_pred_1);
147 info->op_pred_pos = 1;
148 info->init_pred_pos = 0;
149 if (add_l == info->itervar_phi){
150 info->increment = add_r;
151 } else if (add_r == info->itervar_phi){
152 info->increment = add_l;
154 } else if (phi_pred_0_op == op_Sub){
155 info->operation_code = op_Sub;
156 sub_r = get_Sub_right(phi_pred_0);
157 sub_l = get_Sub_left(phi_pred_0);
158 info->op_pred_pos = 0;
159 info->init_pred_pos = 1;
160 if (sub_l == info->itervar_phi){
161 info->increment = sub_r;
162 } else if (sub_r == info->itervar_phi){
163 info->increment = sub_l;
165 } else if (phi_pred_1_op == op_Sub){
166 info->operation_code = op_Sub;
167 sub_r = get_Sub_right(phi_pred_1);
168 sub_l = get_Sub_left(phi_pred_1);
169 info->op_pred_pos = 1;
170 info->init_pred_pos = 0;
171 if (sub_l == info->itervar_phi){
172 info->increment = sub_r;
177 /*Compute the position of the backedge. */
178 if (is_backedge(get_nodes_block(info->itervar_phi), info->op_pred_pos)){
179 info->be_pos = info->op_pred_pos;
180 info->op = get_Phi_pred(info->itervar_phi, info->op_pred_pos);
181 info->init = get_Phi_pred(info->itervar_phi, info->init_pred_pos);
184 if (get_Block_dom_depth(get_nodes_block(info->init)) >=
185 get_Block_dom_depth(get_nodes_block(info->itervar_phi))) {
189 /* This "for" marks if the iteration operation have a Store successor .*/
190 int op_pred = get_irn_n_outs(info->op), Store_in_op = 0, Store_in_phi = 0, cmp_in_phi = 0;
191 for(int i = 1; i <= op_pred; i++){
192 ir_node *out = get_irn_out(info->op, (i-1));
193 ir_op *out_op = get_irn_op(out);
194 if(out_op == op_Store)
198 // Information about loop of itervar_phi.
199 info->l_itervar_phi = get_irn_loop(get_nodes_block(info->itervar_phi));
201 /* This "for" searchs for the Cmp successor of the
202 iter_var to reduce and marks if the iter_var have a Store
203 successor or a successor out of loop.*/
204 info->phi_pred = get_irn_n_outs(info->itervar_phi);
205 for (int i = 1; i <= info->phi_pred; i++) {
206 ir_node *out = get_irn_out(info->itervar_phi, (i-1));
207 ir_op *out_op = get_irn_op(out);
208 if ((get_irn_loop(get_nodes_block(out)) != info->l_itervar_phi) &&
209 ( get_Block_dom_depth(get_nodes_block(out)) >
210 get_Block_dom_depth(get_nodes_block(info->itervar_phi))))
211 info->out_loop_res = 0;
213 if ( out_op == op_Store)
215 else if (out_op == op_Cmp){
221 if((info->phi_pred == 3 && op_pred == 1 && Store_in_phi == 0 && cmp_in_phi == 1) ||
222 (info->phi_pred == 2 && op_pred == 2 && Store_in_op ==0 && info->cmp != NULL ) ||
223 (info->phi_pred == 1 && Store_in_op == 0))
226 // Search for constant of Cmp.
227 if (info->cmp != NULL){
228 if (get_irn_op(get_Cmp_left(info->cmp)) == op_Const)
229 info->cmp_const = get_Cmp_left(info->cmp);
231 info->cmp_const = get_Cmp_right(info->cmp);
233 ir_node *cmp_const_block = get_nodes_block(info->cmp_const);
234 if (get_Block_dom_depth(get_nodes_block(info->init)) >=
235 get_Block_dom_depth(cmp_const_block))
236 info->cmp_init_block = get_nodes_block(info->init);
238 info->cmp_init_block = cmp_const_block;
244 const char *get_irg_dump_name(ir_graph *irg);
246 static INLINE ir_node *
247 my_new_r_Add (ir_graph *irg, ir_node *b, ir_node *op1, ir_node *op2) {
248 ir_mode *m = get_irn_mode(op1);
249 if (mode_is_reference(get_irn_mode (op2)))
250 m = get_irn_mode(op2);
251 return new_r_Add(irg, b, op1, op2, m);
254 static INLINE ir_node *
255 my_new_r_Sub (ir_graph *irg, ir_node *b, ir_node *op1, ir_node *op2) {
256 ir_mode *m = get_irn_mode(op1);
257 if (mode_is_reference(get_irn_mode (op2)))
258 m = get_irn_mode(op2);
259 else if(mode_is_reference(get_irn_mode (op2)) && m == mode_P)
261 return new_r_Sub(irg, b, op1, op2, m);
264 /* Reduce a Add, Sub or Mul node
266 * @param *reduce_var The node to reduce.
267 * @param *ivi Contains the induction variable information.
269 static int reduce(ir_node *reduce_var, induct_var_info *ivi){
272 // Essential conditions for a reducable node.
273 if (get_irn_loop(get_nodes_block(reduce_var)) != ivi->l_itervar_phi) return 0;
275 if(get_irn_op(reduce_var) == op_Mul){
277 n_reduced_expressions++;
278 ir_node *mul_init = NULL;
279 ir_node *mul_const = NULL;
280 // Search for constant and init of strong.
281 ir_node *mul_right = get_Mul_right(reduce_var);
282 ir_node *mul_left = get_Mul_left(reduce_var);
283 ir_op *mul_right_op = get_irn_op(mul_right);
284 ir_op *mul_left_op = get_irn_op(mul_left);
285 if(mul_right_op != op_Const)
286 mul_init = mul_right;
287 else if(mul_left_op != op_Const)
290 if(mul_right_op == op_Const )
291 mul_const = mul_right;
292 else if(mul_left_op == op_Const)
293 mul_const = mul_left;
295 if(mul_const == NULL || mul_init == NULL) return 0;
297 ir_node *in[2], *block_init;
300 ir_node *init_block = get_nodes_block(mul_init);
301 ir_node *increment_block = get_nodes_block(ivi->increment);
302 ir_node *c_block = get_nodes_block(mul_const) ;
304 if (get_Block_dom_depth(increment_block) >= get_Block_dom_depth(c_block))
305 block_inc = increment_block;
309 if (get_Block_dom_depth(init_block) >= get_Block_dom_depth(c_block))
310 block_init = init_block;
312 block_init = c_block;
316 // Essential condition for the constant of strong.
317 if (get_Block_dom_depth(get_nodes_block(mul_const)) >=
318 get_Block_dom_depth(get_nodes_block(ivi->itervar_phi))) return 0;
320 if (get_opt_strength_red_verbose() && get_firm_verbosity() > 1) {
321 printf("The new Phi node is : "); DDMN(ivi->itervar_phi);
322 printf("reducing operation is : "); DDMN(reduce_var);
323 printf("in graph : "); DDMG(current_ir_graph);
326 ivi->new_increment = new_r_Mul (current_ir_graph, block_inc, ivi->increment, mul_const,
327 get_irn_mode(mul_const));
328 if (!(get_irn_op(mul_init) == op_Phi)){
329 ivi->new_init = new_r_Mul (current_ir_graph, block_init, ivi->init, mul_const,
330 get_irn_mode(mul_const));
331 ivi->new_init =my_new_r_Add(current_ir_graph, block_init, ivi->new_init,
334 ivi->new_init = new_r_Mul (current_ir_graph, block_init, ivi->init, mul_const,
335 get_irn_mode(mul_const));
337 /* Generate a new basic induction variable. Break the data flow loop
338 initially by using an Unknown node. */
340 in[ivi->op_pred_pos] = new_Unknown(get_irn_mode(ivi->new_init));
342 in[ivi->init_pred_pos] = ivi->new_init;
343 ivi->new_phi = new_r_Phi(current_ir_graph, get_nodes_block(ivi->itervar_phi), 2, in,
344 get_irn_mode(mul_const));
345 mark_irn_visited(ivi->new_phi);
347 if (ivi->operation_code == op_Add)
348 ivi->new_op =my_new_r_Add(current_ir_graph, get_nodes_block(ivi->op),
349 ivi->new_increment,ivi-> new_phi);
350 else if (ivi->operation_code == op_Sub)
351 ivi->new_op = my_new_r_Sub(current_ir_graph, get_nodes_block(ivi->op),ivi-> new_phi,
354 set_Phi_pred(ivi->new_phi, ivi->op_pred_pos, ivi->new_op);
360 // This for search for a reducible successor of reduc_var.
361 int reduce_var_pred = get_irn_n_outs(reduce_var);
362 if(reduce_var_pred == 1){
363 ir_node *old_ind =get_irn_out(reduce_var, 0);
364 if(get_irn_op(old_ind) == op_Add || get_irn_op(old_ind) == op_Sub ||
365 get_irn_op(old_ind) == op_Mul){
367 ivi->reducible_node = old_ind;
370 /* Replace the use of the strength reduced value. */
371 exchange(reduce_var, ivi->new_phi);
374 if(ivi->new_phi == NULL){
375 ivi->init = new_r_Mul (current_ir_graph, get_nodes_block(ivi->init),
376 mul_const, ivi->init,
377 get_irn_mode(mul_const));
379 ivi->cmp_const = new_r_Mul (current_ir_graph, ivi->cmp_init_block,
380 ivi->cmp_const, mul_const, get_irn_mode(mul_const));
381 ivi->increment = new_r_Mul (current_ir_graph, block_init,
382 ivi->increment, mul_const, get_irn_mode(mul_const));
384 ivi->new_init = new_r_Mul (current_ir_graph, get_nodes_block(ivi->init),
385 mul_const, ivi->new_init,
386 get_irn_mode(mul_const));
387 ivi->new_increment = new_r_Mul (current_ir_graph, block_init,
388 ivi->new_increment, mul_const,
389 get_irn_mode(mul_const));
391 if (get_opt_strength_red_verbose() && get_firm_verbosity() > 1) {
392 printf("\nReducing operation is : "); DDMN(reduce_var);
393 printf("in graph : "); DDMG(current_ir_graph);
398 }else if (get_irn_op (reduce_var) == op_Add){
399 n_reduced_expressions++;
400 ir_node *add_init = NULL;
401 ir_node *add_const = NULL;
403 // Search for constant of add.
404 ir_node *add_right = get_Add_right(reduce_var);
405 ir_node *add_left = get_Add_left(reduce_var);
406 ir_op *add_right_op = get_irn_op(add_right);
407 ir_op *add_left_op = get_irn_op(add_left);
408 if(add_right_op != op_Const)
409 add_init = add_right;
410 else if(add_left_op != op_Const )
412 if(add_right_op == op_Const || add_right_op == op_SymConst)
413 add_const = add_right;
414 else if(add_left_op == op_Const || add_left_op == op_SymConst)
415 add_const = add_left;
416 if(add_const == NULL) return 0;
417 if(ivi->new_phi == NULL){
418 ivi->init = my_new_r_Add (current_ir_graph, get_nodes_block(ivi->init),
419 add_const, ivi->init);
421 ivi->cmp_const = my_new_r_Add (current_ir_graph, ivi->cmp_init_block,
422 add_const, ivi->cmp_const);
424 ivi->new_init = my_new_r_Add (current_ir_graph, get_nodes_block(ivi->init),
425 add_const, ivi->new_init);
427 if (get_opt_strength_red_verbose() && get_firm_verbosity() > 1) {
428 printf("\nReducing operation is : "); DDMN(reduce_var);
429 printf("in graph : "); DDMG(current_ir_graph);
432 }else if(get_irn_op(reduce_var) == op_Sub ){
433 n_reduced_expressions++;
434 ir_node *sub_init = NULL;
435 ir_node *sub_const = NULL;
436 // Search for constant of sub.
437 ir_node *sub_right = get_Sub_right(reduce_var);
438 ir_node *sub_left = get_Sub_left(reduce_var);
439 ir_op *sub_right_op = get_irn_op(sub_right);
440 ir_op *sub_left_op = get_irn_op(sub_left);
441 if(sub_right_op != op_Const)
442 sub_init = sub_right;
443 else if(sub_left_op != op_Const)
445 if(sub_right_op == op_Const)
446 sub_const = sub_right;
447 else if(sub_left_op == op_Const)
448 sub_const = sub_left;
450 if(sub_const == NULL ) return 0;
452 if(ivi->new_phi == NULL){
453 ivi->init = my_new_r_Sub (current_ir_graph, get_nodes_block(ivi->init),
454 ivi->init, sub_const);
455 if (ivi->cmp != NULL)
456 ivi->cmp_const =my_new_r_Sub (current_ir_graph, get_nodes_block(ivi->init),
457 ivi->cmp_const,sub_const);
459 ivi->new_init = my_new_r_Sub (current_ir_graph, get_nodes_block(ivi->init),
460 ivi->new_init, sub_const);
461 if (get_opt_strength_red_verbose() && get_firm_verbosity() > 1) {
462 printf("\nReducing operation is : "); DDMN(reduce_var);
463 printf("in graph : "); DDMG(current_ir_graph);
469 static ir_node *reducible(ir_node *out, induct_var_info *ivi){
471 ir_node *reduced = NULL;
473 if( reduce(out, ivi) )
476 out = get_irn_out(out,0 );
477 pred = get_irn_n_outs(out);
485 * @param *itervar_phi The iteration variable of a loop.
486 * @param *env Free environment pointer.
490 static void reduce_itervar(ir_node *itervar_phi, void *env) {
495 // This "if" finds the inreration variable.
496 ivi.itervar_phi = itervar_phi;
497 if ( (get_irn_op(ivi.itervar_phi) == op_Phi) &&
498 is_induction_variable(&ivi) != NULL ) {
500 for (int i = 1; i <= ivi.phi_pred; i++) {
501 ir_node *out = get_irn_out(ivi.itervar_phi, (i-1));
502 ir_op *out_op = get_irn_op(out);
504 if(ivi.phi_pred == 3 && out != ivi.op && out !=ivi.cmp){
505 ir_node *reduced = reducible(out, &ivi);
507 exchange( reduced, ivi.itervar_phi);
509 } else if (out_op == op_Mul)
510 if(reduce(out, &ivi) && ivi.reducible){
511 ir_node *reduced = reducible(ivi.reducible_node, &ivi);
513 exchange(reduced, ivi.new_phi);
515 set_Phi_pred(ivi.new_phi, ivi.init_pred_pos, ivi.new_init);
516 set_irn_mode(ivi.new_phi,get_irn_mode(ivi.new_init));
517 set_irn_mode(ivi.new_op,get_irn_mode(ivi.new_phi));
520 int op_out = get_irn_n_outs(ivi.op);
521 for (int i = 1; i <= op_out; i++){
522 ir_node *out = get_irn_out(ivi.op, (i-1));
523 ir_op *out_op = get_irn_op(out);
524 if(op_out == 2 && out != ivi.itervar_phi){
525 ir_node *reduced = reducible(out, &ivi);
527 exchange( reduced, ivi.op);
528 }else if (out_op == op_Mul)
529 if(reduce(out, &ivi) && ivi.reducible){
530 ir_node *reduced = reducible(ivi.reducible_node, &ivi);
532 exchange(reduced, ivi.new_phi);
534 set_Phi_pred(ivi.new_phi, ivi.init_pred_pos, ivi.new_init);
535 set_irn_mode(ivi.new_phi,get_irn_mode(ivi.new_init));
536 set_irn_mode(ivi.new_op,get_irn_mode(ivi.new_phi));
541 if(get_irn_op(ivi.op) == op_Add)
542 if(get_Add_left(ivi.op) == ivi.itervar_phi)
543 set_Add_right(ivi.op, ivi.increment);
545 set_Add_left(ivi.op, ivi.increment);
546 else if(get_Sub_left(ivi.op) == ivi.itervar_phi)
547 set_Sub_right(ivi.op, ivi.increment);
549 set_Sub_right(ivi.op, ivi.increment);
550 set_Phi_pred(ivi.itervar_phi, ivi.init_pred_pos, ivi.init);
551 set_irn_mode(ivi.itervar_phi, get_irn_mode(ivi.init));
552 set_irn_mode(ivi.op, get_irn_mode(ivi.itervar_phi));
553 if (ivi.cmp != NULL){
554 set_irn_mode(ivi.cmp_const, get_irn_mode(ivi.itervar_phi));
555 if(get_Cmp_left(ivi.cmp) == ivi.itervar_phi)
556 set_Cmp_right(ivi.cmp, ivi.cmp_const);
558 set_Cmp_left(ivi.cmp, ivi.cmp_const);
564 /* Performs strength reduction for the passed graph. */
565 void reduce_strength(ir_graph *irg) {
566 ir_graph *rem = current_ir_graph;
567 current_ir_graph = irg;
569 if (!get_optimize() || !get_opt_strength_red()) return;
571 n_reduced_expressions = 0;
573 /* -- Precompute some information -- */
574 /* Call algorithm that computes the backedges */
575 construct_cf_backedges(irg);
576 /* Call algorithm that computes the dominator trees. */
578 /* Call algorithm that computes the out edges */
580 /* -- Search expressions that can be optimized -- */
581 irg_walk_graph(irg, NULL, reduce_itervar, NULL);
583 if (get_opt_strength_red_verbose())
584 printf ("\n %d made new_phis und ", n_made_new_phis);
585 printf("reduced %d iteration variables "
586 "in \n graph %s.%s.\n", n_reduced_expressions,
587 get_type_name(get_entity_owner(get_irg_entity(irg))),
588 get_entity_name(get_irg_entity(irg)));
590 current_ir_graph = rem;