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Fix LLVM build.
[mono-project/dkf.git] / mono / mini / ssa.c
blob3b154b455eef8591a8b5946f0c363a6ce3bf702e
1 /*
2 * ssa.c: Static single assign form support for the JIT compiler.
3 *
4 * Author:
5 * Dietmar Maurer (dietmar@ximian.com)
6 *
7 * (C) 2003 Ximian, Inc.
8 */
9 #include <config.h>
10 #include <string.h>
11 #include <mono/metadata/debug-helpers.h>
12 #include <mono/metadata/mempool.h>
13 #include <mono/metadata/mempool-internals.h>
14
15 #ifndef DISABLE_JIT
16
17 #include "mini.h"
18 #ifdef HAVE_ALLOCA_H
19 #include <alloca.h>
20 #endif
21
22 #define USE_ORIGINAL_VARS
23 #define CREATE_PRUNED_SSA
24
25 //#define DEBUG_SSA 1
26
27 #define NEW_PHI(cfg,dest,val) do { \
28 (dest) = mono_mempool_alloc0 ((cfg)->mempool, sizeof (MonoInst)); \
29 (dest)->opcode = OP_PHI; \
30 (dest)->inst_c0 = (val); \
31 (dest)->dreg = (dest)->sreg1 = (dest)->sreg2 = -1; \
32 } while (0)
33
34 typedef struct {
35 MonoBasicBlock *bb;
36 MonoInst *inst;
37 } MonoVarUsageInfo;
38
39 static void
40 unlink_target (MonoBasicBlock *bb, MonoBasicBlock *target)
41 {
42 int i;
43
44 for (i = 0; i < bb->out_count; i++) {
45 if (bb->out_bb [i] == target) {
46 bb->out_bb [i] = bb->out_bb [--bb->out_count];
47 break;
48 }
49 }
50 for (i = 0; i < target->in_count; i++) {
51 if (target->in_bb [i] == bb) {
52 target->in_bb [i] = target->in_bb [--target->in_count];
53 break;
54
55 }
56 }
57 }
58
59 static void
60 unlink_unused_bblocks (MonoCompile *cfg)
61 {
62 int i, j;
63 MonoBasicBlock *bb;
64
65 g_assert (cfg->comp_done & MONO_COMP_REACHABILITY);
66
67 if (G_UNLIKELY (cfg->verbose_level > 1))
68 printf ("\nUNLINK UNUSED BBLOCKS:\n");
69
70 for (bb = cfg->bb_entry; bb && bb->next_bb;) {
71 if (!(bb->next_bb->flags & BB_REACHABLE)) {
72 bb->next_bb = bb->next_bb->next_bb;
73 } else
74 bb = bb->next_bb;
75 }
76
77 for (i = 1; i < cfg->num_bblocks; i++) {
78 bb = cfg->bblocks [i];
79
80 if (!(bb->flags & BB_REACHABLE)) {
81 for (j = 0; j < bb->in_count; j++) {
82 unlink_target (bb->in_bb [j], bb);
83 }
84 for (j = 0; j < bb->out_count; j++) {
85 unlink_target (bb, bb->out_bb [j]);
86 }
87 if (G_UNLIKELY (cfg->verbose_level > 1))
88 printf ("\tUnlinked BB%d\n", bb->block_num);
89 }
90
91 }
92 }
93
94 /**
95 * remove_bb_from_phis:
96 *
97 * Remove BB from the PHI statements in TARGET.
98 */
99 static void
100 remove_bb_from_phis (MonoCompile *cfg, MonoBasicBlock *bb, MonoBasicBlock *target)
101 {
102 MonoInst *ins;
103 int i, j;
104
105 for (i = 0; i < target->in_count; i++) {
106 if (target->in_bb [i] == bb) {
107 break;
108 }
109 }
110 g_assert (i < target->in_count);
111
112 for (ins = target->code; ins; ins = ins->next) {
113 if (MONO_IS_PHI (ins)) {
114 for (j = i; j < ins->inst_phi_args [0] - 1; ++j)
115 ins->inst_phi_args [j + 1] = ins->inst_phi_args [j + 2];
116 ins->inst_phi_args [0] --;
117 }
118 else
119 break;
120 }
121 }
122
123 static inline int
124 op_phi_to_move (int opcode)
125 {
126 switch (opcode) {
127 case OP_PHI:
128 return OP_MOVE;
129 case OP_FPHI:
130 return OP_FMOVE;
131 case OP_VPHI:
132 return OP_VMOVE;
133 case OP_XPHI:
134 return OP_XMOVE;
135 default:
136 g_assert_not_reached ();
137 }
138
139 return -1;
140 }
141
142 static inline void
143 record_use (MonoCompile *cfg, MonoInst *var, MonoBasicBlock *bb, MonoInst *ins)
144 {
145 MonoMethodVar *info;
146 MonoVarUsageInfo *ui = mono_mempool_alloc (cfg->mempool, sizeof (MonoVarUsageInfo));
147
148 info = MONO_VARINFO (cfg, var->inst_c0);
149
150 ui->bb = bb;
151 ui->inst = ins;
152 info->uses = g_list_prepend_mempool (cfg->mempool, info->uses, ui);
153 }
154
155 typedef struct {
156 MonoInst *var;
157 int idx;
158 } RenameInfo;
159
160 /**
161 * mono_ssa_rename_vars:
162 *
163 * Implement renaming of SSA variables. Also compute def-use information in parallel.
164 * @stack_history points to an area of memory which can be used for storing changes
165 * made to the stack, so they can be reverted later.
166 */
167 static void
168 mono_ssa_rename_vars (MonoCompile *cfg, int max_vars, MonoBasicBlock *bb, gboolean *originals_used, MonoInst **stack, guint32 *lvreg_stack, gboolean *lvreg_defined, RenameInfo *stack_history, int stack_history_size)
169 {
170 MonoInst *ins, *new_var;
171 int i, j, idx;
172 GSList *tmp;
173 int stack_history_len = 0;
174
175 if (cfg->verbose_level >= 4)
176 printf ("\nRENAME VARS BLOCK %d:\n", bb->block_num);
177
178 /* First pass: Create new vars */
179 for (ins = bb->code; ins; ins = ins->next) {
180 const char *spec = INS_INFO (ins->opcode);
181 int num_sregs;
182 int sregs [MONO_MAX_SRC_REGS];
183
184 #ifdef DEBUG_SSA
185 printf ("\tProcessing "); mono_print_ins (ins);
186 #endif
187 if (ins->opcode == OP_NOP)
188 continue;
189
190 /* SREGs */
191 num_sregs = mono_inst_get_src_registers (ins, sregs);
192 for (i = 0; i < num_sregs; ++i) {
193 if (spec [MONO_INST_SRC1 + i] != ' ') {
194 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
195 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
196 int idx = var->inst_c0;
197 if (stack [idx]) {
198 if (var->opcode != OP_ARG)
199 g_assert (stack [idx]);
200 sregs [i] = stack [idx]->dreg;
201 record_use (cfg, stack [idx], bb, ins);
202 }
203 else
204 record_use (cfg, var, bb, ins);
205 }
206 else if (G_UNLIKELY (!var && lvreg_stack [sregs [i]]))
207 sregs [i] = lvreg_stack [sregs [i]];
208 }
209 }
210 mono_inst_set_src_registers (ins, sregs);
211
212 if (MONO_IS_STORE_MEMBASE (ins)) {
213 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
214 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
215 int idx = var->inst_c0;
216 if (stack [idx]) {
217 if (var->opcode != OP_ARG)
218 g_assert (stack [idx]);
219 ins->dreg = stack [idx]->dreg;
220 record_use (cfg, stack [idx], bb, ins);
221 }
222 else
223 record_use (cfg, var, bb, ins);
224 }
225 else if (G_UNLIKELY (!var && lvreg_stack [ins->dreg]))
226 ins->dreg = lvreg_stack [ins->dreg];
227 }
228
229 /* DREG */
230 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
231 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
232 MonoMethodVar *info;
233
234 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
235 idx = var->inst_c0;
236 g_assert (idx < max_vars);
237
238 if (var->opcode == OP_ARG)
239 originals_used [idx] = TRUE;
240
241 /* FIXME: */
242 g_assert (stack_history_len < stack_history_size);
243 stack_history [stack_history_len].var = stack [idx];
244 stack_history [stack_history_len].idx = idx;
245 stack_history_len ++;
246
247 if (originals_used [idx]) {
248 new_var = mono_compile_create_var (cfg, var->inst_vtype, OP_LOCAL);
249 new_var->flags = var->flags;
250 MONO_VARINFO (cfg, new_var->inst_c0)->reg = idx;
251
252 if (cfg->verbose_level >= 4)
253 printf (" R%d -> R%d\n", var->dreg, new_var->dreg);
254
255 stack [idx] = new_var;
256
257 ins->dreg = new_var->dreg;
258 var = new_var;
259 }
260 else {
261 stack [idx] = var;
262 originals_used [idx] = TRUE;
263 }
264
265 info = MONO_VARINFO (cfg, var->inst_c0);
266 info->def = ins;
267 info->def_bb = bb;
268 }
269 else if (G_UNLIKELY (!var && lvreg_defined [ins->dreg] && (ins->dreg >= MONO_MAX_IREGS))) {
270 /* Perform renaming for local vregs */
271 lvreg_stack [ins->dreg] = vreg_is_ref (cfg, ins->dreg) ? mono_alloc_ireg_ref (cfg) : mono_alloc_preg (cfg);
272 ins->dreg = lvreg_stack [ins->dreg];
273 }
274 else
275 lvreg_defined [ins->dreg] = TRUE;
276 }
277
278 #ifdef DEBUG_SSA
279 printf ("\tAfter processing "); mono_print_ins (ins);
280 #endif
281
282 }
283
284 /* Rename PHI arguments in succeeding bblocks */
285 for (i = 0; i < bb->out_count; i++) {
286 MonoBasicBlock *n = bb->out_bb [i];
287
288 for (j = 0; j < n->in_count; j++)
289 if (n->in_bb [j] == bb)
290 break;
291
292 for (ins = n->code; ins; ins = ins->next) {
293 if (MONO_IS_PHI (ins)) {
294 idx = ins->inst_c0;
295 if (stack [idx])
296 new_var = stack [idx];
297 else
298 new_var = cfg->varinfo [idx];
299 #ifdef DEBUG_SSA
300 printf ("FOUND PHI %d (%d, %d)\n", idx, j, new_var->inst_c0);
301 #endif
302 ins->inst_phi_args [j + 1] = new_var->dreg;
303 record_use (cfg, new_var, n, ins);
304 if (G_UNLIKELY (cfg->verbose_level >= 4))
305 printf ("\tAdd PHI R%d <- R%d to BB%d\n", ins->dreg, new_var->dreg, n->block_num);
306 }
307 else
308 /* The phi nodes are at the beginning of the bblock */
309 break;
310 }
311 }
312
313 if (bb->dominated) {
314 for (tmp = bb->dominated; tmp; tmp = tmp->next) {
315 mono_ssa_rename_vars (cfg, max_vars, (MonoBasicBlock *)tmp->data, originals_used, stack, lvreg_stack, lvreg_defined, stack_history + stack_history_len, stack_history_size - stack_history_len);
316 }
317 }
318
319 /* Restore stack */
320 for (i = stack_history_len - 1; i >= 0; i--) {
321 stack [stack_history [i].idx] = stack_history [i].var;
322 }
323
324 cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
325 }
326
327 void
328 mono_ssa_compute (MonoCompile *cfg)
329 {
330 int i, j, idx, bitsize;
331 MonoBitSet *set;
332 MonoMethodVar *vinfo = g_new0 (MonoMethodVar, cfg->num_varinfo);
333 MonoInst *ins, **stack;
334 guint8 *buf, *buf_start;
335 RenameInfo *stack_history;
336 int stack_history_size;
337 gboolean *originals;
338 guint32 *lvreg_stack;
339 gboolean *lvreg_defined;
340
341 g_assert (!(cfg->comp_done & MONO_COMP_SSA));
342
343 g_assert (!cfg->disable_ssa);
344
345 if (cfg->verbose_level >= 4)
346 printf ("\nCOMPUTE SSA %d (R%d-)\n\n", cfg->num_varinfo, cfg->next_vreg);
347
348 #ifdef CREATE_PRUNED_SSA
349 /* we need liveness for pruned SSA */
350 if (!(cfg->comp_done & MONO_COMP_LIVENESS))
351 mono_analyze_liveness (cfg);
352 #endif
353
354 mono_compile_dominator_info (cfg, MONO_COMP_DOM | MONO_COMP_IDOM | MONO_COMP_DFRONTIER);
355
356 bitsize = mono_bitset_alloc_size (cfg->num_bblocks, 0);
357 buf = buf_start = g_malloc0 (mono_bitset_alloc_size (cfg->num_bblocks, 0) * cfg->num_varinfo);
358
359 for (i = 0; i < cfg->num_varinfo; ++i) {
360 vinfo [i].def_in = mono_bitset_mem_new (buf, cfg->num_bblocks, 0);
361 buf += bitsize;
362 vinfo [i].idx = i;
363 /* implicit reference at start */
364 if (cfg->varinfo [i]->opcode == OP_ARG)
365 mono_bitset_set_fast (vinfo [i].def_in, 0);
366 }
367
368 for (i = 0; i < cfg->num_bblocks; ++i) {
369 MONO_BB_FOR_EACH_INS (cfg->bblocks [i], ins) {
370 if (ins->opcode == OP_NOP)
371 continue;
372
373 if (!MONO_IS_STORE_MEMBASE (ins) && get_vreg_to_inst (cfg, ins->dreg)) {
374 mono_bitset_set_fast (vinfo [get_vreg_to_inst (cfg, ins->dreg)->inst_c0].def_in, i);
375 }
376 }
377 }
378
379 /* insert phi functions */
380 for (i = 0; i < cfg->num_varinfo; ++i) {
381 MonoInst *var = cfg->varinfo [i];
382
383 #if SIZEOF_REGISTER == 4
384 if (var->type == STACK_I8 && !COMPILE_LLVM (cfg))
385 continue;
386 #endif
387 if (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))
388 continue;
389
390 /* Most variables have only one definition */
391 if (mono_bitset_count (vinfo [i].def_in) <= 1)
392 continue;
393
394 set = mono_compile_iterated_dfrontier (cfg, vinfo [i].def_in);
395
396 if (cfg->verbose_level >= 4) {
397 if (mono_bitset_count (set) > 0) {
398 printf ("\tR%d needs PHI functions in ", var->dreg);
399 mono_blockset_print (cfg, set, "", -1);
400 }
401 }
402
403 mono_bitset_foreach_bit (set, idx, cfg->num_bblocks) {
404 MonoBasicBlock *bb = cfg->bblocks [idx];
405
406 /* fixme: create pruned SSA? we would need liveness information for that */
407
408 if (bb == cfg->bb_exit && !COMPILE_LLVM (cfg))
409 continue;
410
411 if ((cfg->comp_done & MONO_COMP_LIVENESS) && !mono_bitset_test_fast (bb->live_in_set, i)) {
412 //printf ("%d is not live in BB%d %s\n", i, bb->block_num, mono_method_full_name (cfg->method, TRUE));
413 continue;
414 }
415
416 NEW_PHI (cfg, ins, i);
417
418 switch (var->type) {
419 case STACK_I4:
420 case STACK_I8:
421 case STACK_PTR:
422 case STACK_MP:
423 case STACK_OBJ:
424 ins->opcode = OP_PHI;
425 break;
426 case STACK_R8:
427 ins->opcode = OP_FPHI;
428 break;
429 case STACK_VTYPE:
430 ins->opcode = MONO_CLASS_IS_SIMD (cfg, var->klass) ? OP_XPHI : OP_VPHI;
431 break;
432 }
433
434 if (var->inst_vtype->byref)
435 ins->klass = mono_defaults.int_class;
436 else
437 ins->klass = var->klass;
438
439 ins->inst_phi_args = mono_mempool_alloc0 (cfg->mempool, sizeof (int) * (cfg->bblocks [idx]->in_count + 1));
440 ins->inst_phi_args [0] = cfg->bblocks [idx]->in_count;
441
442 /* For debugging */
443 for (j = 0; j < cfg->bblocks [idx]->in_count; ++j)
444 ins->inst_phi_args [j + 1] = -1;
445
446 ins->dreg = cfg->varinfo [i]->dreg;
447
448 mono_bblock_insert_before_ins (bb, bb->code, ins);
449
450 #ifdef DEBUG_SSA
451 printf ("ADD PHI BB%d %s\n", cfg->bblocks [idx]->block_num, mono_method_full_name (cfg->method, TRUE));
452 #endif
453 }
454 }
455
456 /* free the stuff */
457 g_free (vinfo);
458 g_free (buf_start);
459
460 /* Renaming phase */
461
462 stack = alloca (sizeof (MonoInst *) * cfg->num_varinfo);
463 memset (stack, 0, sizeof (MonoInst *) * cfg->num_varinfo);
464
465 lvreg_stack = g_new0 (guint32, cfg->next_vreg);
466 lvreg_defined = g_new0 (gboolean, cfg->next_vreg);
467 stack_history_size = 10240;
468 stack_history = g_new (RenameInfo, stack_history_size);
469 originals = g_new0 (gboolean, cfg->num_varinfo);
470 mono_ssa_rename_vars (cfg, cfg->num_varinfo, cfg->bb_entry, originals, stack, lvreg_stack, lvreg_defined, stack_history, stack_history_size);
471 g_free (stack_history);
472 g_free (originals);
473 g_free (lvreg_stack);
474 g_free (lvreg_defined);
475
476 if (cfg->verbose_level >= 4)
477 printf ("\nEND COMPUTE SSA.\n\n");
478
479 cfg->comp_done |= MONO_COMP_SSA;
480 }
481
482 void
483 mono_ssa_remove (MonoCompile *cfg)
484 {
485 MonoInst *ins, *var, *move;
486 int bbindex, i, j, first;
487
488 g_assert (cfg->comp_done & MONO_COMP_SSA);
489
490 for (i = 0; i < cfg->num_bblocks; ++i) {
491 MonoBasicBlock *bb = cfg->bblocks [i];
492
493 if (cfg->verbose_level >= 4)
494 printf ("\nREMOVE SSA %d:\n", bb->block_num);
495
496 for (ins = bb->code; ins; ins = ins->next) {
497 if (MONO_IS_PHI (ins)) {
498 g_assert (ins->inst_phi_args [0] == bb->in_count);
499 var = get_vreg_to_inst (cfg, ins->dreg);
500
501 /* Check for PHI nodes where all the inputs are the same */
502 first = ins->inst_phi_args [1];
503
504 for (j = 1; j < bb->in_count; ++j)
505 if (first != ins->inst_phi_args [j + 1])
506 break;
507
508 if ((bb->in_count > 1) && (j == bb->in_count)) {
509 ins->opcode = op_phi_to_move (ins->opcode);
510 if (ins->opcode == OP_VMOVE)
511 g_assert (ins->klass);
512 ins->sreg1 = first;
513 } else {
514 for (j = 0; j < bb->in_count; j++) {
515 MonoBasicBlock *pred = bb->in_bb [j];
516 int sreg = ins->inst_phi_args [j + 1];
517
518 if (cfg->verbose_level >= 4)
519 printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
520 if (var->dreg != sreg) {
521 MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
522 if (move->opcode == OP_VMOVE) {
523 g_assert (ins->klass);
524 move->klass = ins->klass;
525 }
526 move->dreg = var->dreg;
527 move->sreg1 = sreg;
528 mono_add_ins_to_end (pred, move);
529 }
530 }
531
532 ins->opcode = OP_NOP;
533 ins->dreg = -1;
534 }
535 }
536 }
537 }
538
539 if (cfg->verbose_level >= 4) {
540 for (i = 0; i < cfg->num_bblocks; ++i) {
541 MonoBasicBlock *bb = cfg->bblocks [i];
542
543 mono_print_bb (bb, "AFTER REMOVE SSA:");
544 }
545 }
546
547 /*
548 * Removal of SSA form introduces many copies. To avoid this, we tyry to coalesce
549 * the variables if possible. Since the newly introduced SSA variables don't
550 * have overlapping live ranges (because we don't do agressive optimization), we
551 * can coalesce them into the original variable.
552 */
553
554 for (bbindex = 0; bbindex < cfg->num_bblocks; ++bbindex) {
555 MonoBasicBlock *bb = cfg->bblocks [bbindex];
556
557 for (ins = bb->code; ins; ins = ins->next) {
558 const char *spec = INS_INFO (ins->opcode);
559 int num_sregs;
560 int sregs [MONO_MAX_SRC_REGS];
561
562 if (ins->opcode == OP_NOP)
563 continue;
564
565 if (spec [MONO_INST_DEST] != ' ') {
566 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
567
568 if (var) {
569 MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
570
571 /*
572 * The third condition avoids coalescing with variables eliminated
573 * during deadce.
574 */
575 if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
576 printf ("COALESCE: R%d -> R%d\n", ins->dreg, cfg->varinfo [vmv->reg]->dreg);
577 ins->dreg = cfg->varinfo [vmv->reg]->dreg;
578 }
579 }
580 }
581
582 num_sregs = mono_inst_get_src_registers (ins, sregs);
583 for (i = 0; i < num_sregs; ++i) {
584 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
585
586 if (var) {
587 MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
588
589 if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
590 printf ("COALESCE: R%d -> R%d\n", sregs [i], cfg->varinfo [vmv->reg]->dreg);
591 sregs [i] = cfg->varinfo [vmv->reg]->dreg;
592 }
593 }
594 }
595 mono_inst_set_src_registers (ins, sregs);
596 }
597 }
598
599 for (i = 0; i < cfg->num_varinfo; ++i) {
600 MONO_VARINFO (cfg, i)->reg = -1;
601 }
602
603 if (cfg->comp_done & MONO_COMP_REACHABILITY)
604 unlink_unused_bblocks (cfg);
605
606 cfg->comp_done &= ~MONO_COMP_LIVENESS;
607
608 cfg->comp_done &= ~MONO_COMP_SSA;
609 }
610
611 static void
612 mono_ssa_create_def_use (MonoCompile *cfg)
613 {
614 MonoBasicBlock *bb;
615 MonoInst *ins;
616 int i;
617
618 g_assert (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE));
619
620 for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
621 for (ins = bb->code; ins; ins = ins->next) {
622 const char *spec = INS_INFO (ins->opcode);
623 MonoMethodVar *info;
624 int num_sregs;
625 int sregs [MONO_MAX_SRC_REGS];
626
627 if (ins->opcode == OP_NOP)
628 continue;
629
630 /* SREGs */
631 num_sregs = mono_inst_get_src_registers (ins, sregs);
632 for (i = 0; i < num_sregs; ++i) {
633 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
634 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
635 record_use (cfg, var, bb, ins);
636 }
637
638 if (MONO_IS_STORE_MEMBASE (ins)) {
639 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
640 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
641 record_use (cfg, var, bb, ins);
642 }
643
644 if (MONO_IS_PHI (ins)) {
645 for (i = ins->inst_phi_args [0]; i > 0; i--) {
646 g_assert (ins->inst_phi_args [i] != -1);
647 record_use (cfg, get_vreg_to_inst (cfg, ins->inst_phi_args [i]), bb, ins);
648 }
649 }
650
651 /* DREG */
652 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
653 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
654
655 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
656 info = MONO_VARINFO (cfg, var->inst_c0);
657 info->def = ins;
658 info->def_bb = bb;
659 }
660 }
661 }
662 }
663
664 cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
665 }
666
667 static void
668 mono_ssa_copyprop (MonoCompile *cfg)
669 {
670 int i, index;
671 GList *l;
672
673 g_assert ((cfg->comp_done & MONO_COMP_SSA_DEF_USE));
674
675 for (index = 0; index < cfg->num_varinfo; ++index) {
676 MonoInst *var = cfg->varinfo [index];
677 MonoMethodVar *info = MONO_VARINFO (cfg, index);
678
679 if (info->def && (MONO_IS_MOVE (info->def))) {
680 MonoInst *var2 = get_vreg_to_inst (cfg, info->def->sreg1);
681
682 if (var2 && !(var2->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)) && MONO_VARINFO (cfg, var2->inst_c0)->def && (!MONO_IS_PHI (MONO_VARINFO (cfg, var2->inst_c0)->def))) {
683 /* Rewrite all uses of var to be uses of var2 */
684 int dreg = var->dreg;
685 int sreg1 = var2->dreg;
686
687 l = info->uses;
688 while (l) {
689 MonoVarUsageInfo *u = (MonoVarUsageInfo*)l->data;
690 MonoInst *ins = u->inst;
691 GList *next = l->next;
692 int num_sregs;
693 int sregs [MONO_MAX_SRC_REGS];
694
695 num_sregs = mono_inst_get_src_registers (ins, sregs);
696 for (i = 0; i < num_sregs; ++i) {
697 if (sregs [i] == dreg)
698 break;
699 }
700 if (i < num_sregs) {
701 g_assert (sregs [i] == dreg);
702 sregs [i] = sreg1;
703 mono_inst_set_src_registers (ins, sregs);
704 } else if (MONO_IS_STORE_MEMBASE (ins) && ins->dreg == dreg) {
705 ins->dreg = sreg1;
706 } else if (MONO_IS_PHI (ins)) {
707 for (i = ins->inst_phi_args [0]; i > 0; i--) {
708 int sreg = ins->inst_phi_args [i];
709 if (sreg == var->dreg)
710 break;
711 }
712 g_assert (i > 0);
713 ins->inst_phi_args [i] = sreg1;
714 }
715 else
716 g_assert_not_reached ();
717
718 record_use (cfg, var2, u->bb, ins);
719
720 l = next;
721 }
722
723 info->uses = NULL;
724 }
725 }
726 }
727
728 if (cfg->verbose_level >= 4) {
729 MonoBasicBlock *bb;
730
731 for (bb = cfg->bb_entry; bb; bb = bb->next_bb)
732 mono_print_bb (bb, "AFTER SSA COPYPROP");
733 }
734 }
735
736 static int
737 evaluate_ins (MonoCompile *cfg, MonoInst *ins, MonoInst **res, MonoInst **carray)
738 {
739 MonoInst *args [MONO_MAX_SRC_REGS];
740 int rs [MONO_MAX_SRC_REGS];
741 MonoInst *c0;
742 gboolean const_args = TRUE;
743 const char *spec = INS_INFO (ins->opcode);
744 int num_sregs, i;
745 int sregs [MONO_MAX_SRC_REGS];
746
747 /* Short-circuit this */
748 if (ins->opcode == OP_ICONST) {
749 *res = ins;
750 return 1;
751 }
752
753 if (ins->opcode == OP_NOP)
754 return 2;
755
756 num_sregs = mono_inst_get_src_registers (ins, sregs);
757 for (i = 0; i < MONO_MAX_SRC_REGS; ++i)
758 args [i] = NULL;
759 for (i = 0; i < num_sregs; ++i) {
760 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
761
762 rs [i] = 2;
763 args [i] = carray [sregs [i]];
764 if (args [i])
765 rs [i] = 1;
766 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
767 rs [i] = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
768 if (rs [i] != 1)
769 const_args = FALSE;
770 }
771
772 c0 = NULL;
773
774 if (num_sregs > 0 && const_args) {
775 g_assert (num_sregs <= 2);
776 if ((spec [MONO_INST_DEST] != ' ') && carray [ins->dreg]) {
777 // Cached value
778 *res = carray [ins->dreg];
779 return 1;
780 }
781 c0 = mono_constant_fold_ins (cfg, ins, args [0], args [1], FALSE);
782 if (c0) {
783 if (G_UNLIKELY (cfg->verbose_level > 1)) {
784 printf ("\t cfold -> ");
785 mono_print_ins (c0);
786 }
787 *res = c0;
788 return 1;
789 }
790 else
791 /* Can't cfold this ins */
792 return 2;
793 }
794
795 if (num_sregs == 0)
796 return 2;
797 for (i = 0; i < num_sregs; ++i) {
798 if (rs [i] == 2)
799 return 2;
800 }
801 return 0;
802 }
803
804 static inline void
805 change_varstate (MonoCompile *cfg, GList **cvars, MonoMethodVar *info, int state, MonoInst *c0, MonoInst **carray)
806 {
807 if (info->cpstate >= state)
808 return;
809
810 info->cpstate = state;
811
812 if (G_UNLIKELY (cfg->verbose_level > 1))
813 printf ("\tState of R%d set to %d\n", cfg->varinfo [info->idx]->dreg, info->cpstate);
814
815 if (state == 1)
816 g_assert (c0);
817
818 carray [cfg->varinfo [info->idx]->dreg] = c0;
819
820 if (!g_list_find (*cvars, info)) {
821 *cvars = g_list_prepend (*cvars, info);
822 }
823 }
824
825 static inline void
826 add_cprop_bb (MonoCompile *cfg, MonoBasicBlock *bb, GList **bblist)
827 {
828 if (G_UNLIKELY (cfg->verbose_level > 1))
829 printf ("\tAdd BB%d to worklist\n", bb->block_num);
830
831 if (!(bb->flags & BB_REACHABLE)) {
832 bb->flags |= BB_REACHABLE;
833 *bblist = g_list_prepend (*bblist, bb);
834 }
835 }
836
837 static void
838 visit_inst (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, GList **cvars, GList **bblist, MonoInst **carray)
839 {
840 const char *spec = INS_INFO (ins->opcode);
841
842 if (ins->opcode == OP_NOP)
843 return;
844
845 if (cfg->verbose_level > 1)
846 mono_print_ins (ins);
847
848 /* FIXME: Support longs/floats */
849 /* FIXME: Work on vregs as well */
850
851 if (MONO_IS_PHI (ins)) {
852 MonoMethodVar *info = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, ins->dreg)->inst_c0);
853 MonoInst *c0 = NULL;
854 int j;
855
856 for (j = 1; j <= ins->inst_phi_args [0]; j++) {
857 MonoInst *var = get_vreg_to_inst (cfg, ins->inst_phi_args [j]);
858 MonoMethodVar *mv = MONO_VARINFO (cfg, var->inst_c0);
859 MonoInst *src = mv->def;
860
861 if (mv->def_bb && !(mv->def_bb->flags & BB_REACHABLE))
862 continue;
863
864 if (!mv->def || !src || mv->cpstate == 2) {
865 change_varstate (cfg, cvars, info, 2, NULL, carray);
866 break;
867 }
868
869 if (mv->cpstate == 0)
870 continue;
871
872 g_assert (carray [var->dreg]);
873
874 if (!c0)
875 c0 = carray [var->dreg];
876
877 /* FIXME: */
878 if (c0->opcode != OP_ICONST) {
879 change_varstate (cfg, cvars, info, 2, NULL, carray);
880 break;
881 }
882
883 if (carray [var->dreg]->inst_c0 != c0->inst_c0) {
884 change_varstate (cfg, cvars, info, 2, NULL, carray);
885 break;
886 }
887 }
888
889 if (c0 && info->cpstate < 1) {
890 change_varstate (cfg, cvars, info, 1, c0, carray);
891
892 g_assert (c0->opcode == OP_ICONST);
893 }
894 }
895 else if (!MONO_IS_STORE_MEMBASE (ins) && ((spec [MONO_INST_SRC1] != ' ') || (spec [MONO_INST_SRC2] != ' ') || (spec [MONO_INST_DEST] != ' '))) {
896 MonoInst *var, *c0;
897 int state;
898
899 if (spec [MONO_INST_DEST] != ' ')
900 var = get_vreg_to_inst (cfg, ins->dreg);
901 else
902 var = NULL;
903
904 c0 = NULL;
905 state = evaluate_ins (cfg, ins, &c0, carray);
906
907 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
908 MonoMethodVar *info = MONO_VARINFO (cfg, var->inst_c0);
909
910 if (info->cpstate < 2) {
911 if (state == 1)
912 change_varstate (cfg, cvars, info, 1, c0, carray);
913 else if (state == 2)
914 change_varstate (cfg, cvars, info, 2, NULL, carray);
915 }
916 }
917 else if (!var && (ins->dreg != -1)) {
918 /*
919 * We don't record def-use information for local vregs since it would be
920 * expensive. Instead, we depend on the fact that all uses of the vreg are in
921 * the same bblock, so they will be examined after the definition.
922 * FIXME: This isn't true if the ins is visited through an SSA edge.
923 */
924 if (c0) {
925 carray [ins->dreg] = c0;
926 } else {
927 if (carray [ins->dreg]) {
928 /*
929 * The state of the vreg changed from constant to non-constant
930 * -> need to rescan the whole bblock.
931 */
932 carray [ins->dreg] = NULL;
933 /* FIXME: Speed this up */
934
935 if (!g_list_find (*bblist, bb))
936 *bblist = g_list_prepend (*bblist, bb);
937 }
938 }
939 }
940
941 if (MONO_IS_JUMP_TABLE (ins)) {
942 int i;
943 MonoJumpInfoBBTable *table = MONO_JUMP_TABLE_FROM_INS (ins);
944
945 if (!ins->next || ins->next->opcode != OP_PADD) {
946 /* The PADD was optimized away */
947 /* FIXME: handle this as well */
948 for (i = 0; i < table->table_size; i++)
949 if (table->table [i])
950 add_cprop_bb (cfg, table->table [i], bblist);
951 return;
952 }
953
954 g_assert (ins->next->opcode == OP_PADD);
955 g_assert (ins->next->sreg1 == ins->dreg);
956
957 if (carray [ins->next->sreg2]) {
958 #if SIZEOF_REGISTER == 8
959 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
960 #else
961 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
962 #endif
963 if ((idx < 0) || (idx >= table->table_size))
964 /* Out-of-range, no branch is executed */
965 return;
966 else
967 if (table->table [idx])
968 add_cprop_bb (cfg, table->table [idx], bblist);
969 }
970 else {
971 for (i = 0; i < table->table_size; i++)
972 if (table->table [i])
973 add_cprop_bb (cfg, table->table [i], bblist);
974 }
975 }
976
977 if (ins->opcode == OP_SWITCH) {
978 int i;
979 MonoJumpInfoBBTable *table = ins->inst_p0;
980
981 for (i = 0; i < table->table_size; i++)
982 if (table->table [i])
983 add_cprop_bb (cfg, table->table [i], bblist);
984 }
985
986 /* Handle COMPARE+BRCOND pairs */
987 if (ins->next && MONO_IS_COND_BRANCH_OP (ins->next)) {
988 if (c0) {
989 g_assert (c0->opcode == OP_ICONST);
990
991 if (c0->inst_c0)
992 ins->next->flags |= MONO_INST_CFOLD_TAKEN;
993 else
994 ins->next->flags |= MONO_INST_CFOLD_NOT_TAKEN;
995 }
996 else {
997 ins->next->flags &= ~(MONO_INST_CFOLD_TAKEN | MONO_INST_CFOLD_NOT_TAKEN);
998 }
999
1000 visit_inst (cfg, bb, ins->next, cvars, bblist, carray);
1001 }
1002 } else if (ins->opcode == OP_BR) {
1003 add_cprop_bb (cfg, ins->inst_target_bb, bblist);
1004 } else if (MONO_IS_COND_BRANCH_OP (ins)) {
1005 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1006 add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1007 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1008 if (ins->inst_false_bb)
1009 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1010 } else {
1011 add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1012 if (ins->inst_false_bb)
1013 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1014 }
1015 }
1016 }
1017
1018 /**
1019 * fold_ins:
1020 *
1021 * Replace INS with its constant value, if it exists
1022 */
1023 static void
1024 fold_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **carray)
1025 {
1026 const char *spec = INS_INFO (ins->opcode);
1027 int opcode2;
1028 int num_sregs = mono_inst_get_num_src_registers (ins);
1029
1030 if ((ins->opcode != OP_NOP) && (ins->dreg != -1) && !MONO_IS_STORE_MEMBASE (ins)) {
1031 if (carray [ins->dreg] && (spec [MONO_INST_DEST] == 'i') && (ins->dreg >= MONO_MAX_IREGS)) {
1032 /* Perform constant folding */
1033 /* FIXME: */
1034 g_assert (carray [ins->dreg]->opcode == OP_ICONST);
1035 ins->opcode = OP_ICONST;
1036 ins->inst_c0 = carray [ins->dreg]->inst_c0;
1037 MONO_INST_NULLIFY_SREGS (ins);
1038 } else if (num_sregs == 2 && carray [ins->sreg2]) {
1039 /* Perform op->op_imm conversion */
1040 opcode2 = mono_op_to_op_imm (ins->opcode);
1041 if (opcode2 != -1) {
1042 ins->opcode = opcode2;
1043 ins->inst_imm = carray [ins->sreg2]->inst_c0;
1044 ins->sreg2 = -1;
1045
1046 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
1047 ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
1048 }
1049 } else {
1050 /* FIXME: Handle 3 op insns */
1051 }
1052
1053 if (MONO_IS_JUMP_TABLE (ins)) {
1054 int i;
1055 MonoJumpInfoBBTable *table = MONO_JUMP_TABLE_FROM_INS (ins);
1056
1057 if (!ins->next || ins->next->opcode != OP_PADD) {
1058 /* The PADD was optimized away */
1059 /* FIXME: handle this as well */
1060 return;
1061 }
1062
1063 g_assert (ins->next->opcode == OP_PADD);
1064 g_assert (ins->next->sreg1 == ins->dreg);
1065 g_assert (ins->next->next->opcode == OP_LOAD_MEMBASE);
1066
1067 if (carray [ins->next->sreg2]) {
1068 /* Convert to a simple branch */
1069 #if SIZEOF_REGISTER == 8
1070 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1071 #else
1072 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1073 #endif
1074
1075 if (!((idx >= 0) && (idx < table->table_size))) {
1076 /* Out of range, eliminate the whole switch */
1077 for (i = 0; i < table->table_size; ++i) {
1078 remove_bb_from_phis (cfg, bb, table->table [i]);
1079 mono_unlink_bblock (cfg, bb, table->table [i]);
1080 }
1081
1082 NULLIFY_INS (ins);
1083 NULLIFY_INS (ins->next);
1084 NULLIFY_INS (ins->next->next);
1085 if (ins->next->next->next)
1086 NULLIFY_INS (ins->next->next->next);
1087
1088 return;
1089 }
1090
1091 if (!ins->next->next->next || ins->next->next->next->opcode != OP_BR_REG) {
1092 /* A one-way switch which got optimized away */
1093 if (G_UNLIKELY (cfg->verbose_level > 1)) {
1094 printf ("\tNo cfold on ");
1095 mono_print_ins (ins);
1096 }
1097 return;
1098 }
1099
1100 if (G_UNLIKELY (cfg->verbose_level > 1)) {
1101 printf ("\tcfold on ");
1102 mono_print_ins (ins);
1103 }
1104
1105 /* Unlink target bblocks */
1106 for (i = 0; i < table->table_size; ++i) {
1107 if (i != idx) {
1108 remove_bb_from_phis (cfg, bb, table->table [i]);
1109 mono_unlink_bblock (cfg, bb, table->table [i]);
1110 }
1111 }
1112
1113 /* Change the OP_BR_REG to a simple branch */
1114 ins->next->next->next->opcode = OP_BR;
1115 ins->next->next->next->inst_target_bb = table->table [idx];
1116 ins->next->next->next->sreg1 = -1;
1117
1118 /* Nullify the other instructions */
1119 NULLIFY_INS (ins);
1120 NULLIFY_INS (ins->next);
1121 NULLIFY_INS (ins->next->next);
1122 }
1123 }
1124 }
1125 else if (MONO_IS_COND_BRANCH_OP (ins)) {
1126 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1127 remove_bb_from_phis (cfg, bb, ins->inst_false_bb);
1128 mono_unlink_bblock (cfg, bb, ins->inst_false_bb);
1129 ins->opcode = OP_BR;
1130 ins->inst_target_bb = ins->inst_true_bb;
1131 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1132 remove_bb_from_phis (cfg, bb, ins->inst_true_bb);
1133 mono_unlink_bblock (cfg, bb, ins->inst_true_bb);
1134 ins->opcode = OP_BR;
1135 ins->inst_target_bb = ins->inst_false_bb;
1136 }
1137 }
1138 }
1139
1140 void
1141 mono_ssa_cprop (MonoCompile *cfg)
1142 {
1143 MonoInst **carray;
1144 MonoBasicBlock *bb;
1145 GList *bblock_list, *cvars;
1146 GList *tmp;
1147 int i;
1148 //printf ("SIMPLE OPTS BB%d %s\n", bb->block_num, mono_method_full_name (cfg->method, TRUE));
1149
1150 carray = g_new0 (MonoInst*, cfg->next_vreg);
1151
1152 if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1153 mono_ssa_create_def_use (cfg);
1154
1155 bblock_list = g_list_prepend (NULL, cfg->bb_entry);
1156 cfg->bb_entry->flags |= BB_REACHABLE;
1157
1158 memset (carray, 0, sizeof (MonoInst *) * cfg->num_varinfo);
1159
1160 for (i = 0; i < cfg->num_varinfo; i++) {
1161 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1162 if (!info->def)
1163 info->cpstate = 2;
1164 }
1165
1166 for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1167 /*
1168 * FIXME: This should be bb->flags & BB_FLAG_EXCEPTION_HANDLER, but
1169 * that would still allow unreachable try's to be removed.
1170 */
1171 if (bb->region)
1172 add_cprop_bb (cfg, bb, &bblock_list);
1173 }
1174
1175 cvars = NULL;
1176
1177 while (bblock_list) {
1178 MonoInst *inst;
1179
1180 bb = (MonoBasicBlock *)bblock_list->data;
1181
1182 bblock_list = g_list_delete_link (bblock_list, bblock_list);
1183
1184 g_assert (bb->flags & BB_REACHABLE);
1185
1186 /*
1187 * Some bblocks are linked to 2 others even through they fall through to the
1188 * next bblock.
1189 */
1190 if (!(bb->last_ins && MONO_IS_BRANCH_OP (bb->last_ins))) {
1191 for (i = 0; i < bb->out_count; ++i)
1192 add_cprop_bb (cfg, bb->out_bb [i], &bblock_list);
1193 }
1194
1195 if (cfg->verbose_level > 1)
1196 printf ("\nSSA CONSPROP BB%d:\n", bb->block_num);
1197
1198 for (inst = bb->code; inst; inst = inst->next) {
1199 visit_inst (cfg, bb, inst, &cvars, &bblock_list, carray);
1200 }
1201
1202 while (cvars) {
1203 MonoMethodVar *info = (MonoMethodVar *)cvars->data;
1204 cvars = g_list_delete_link (cvars, cvars);
1205
1206 for (tmp = info->uses; tmp; tmp = tmp->next) {
1207 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1208 if (!(ui->bb->flags & BB_REACHABLE))
1209 continue;
1210 visit_inst (cfg, ui->bb, ui->inst, &cvars, &bblock_list, carray);
1211 }
1212 }
1213 }
1214
1215 for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1216 MonoInst *inst;
1217 for (inst = bb->code; inst; inst = inst->next) {
1218 fold_ins (cfg, bb, inst, carray);
1219 }
1220 }
1221
1222 g_free (carray);
1223
1224 cfg->comp_done |= MONO_COMP_REACHABILITY;
1225
1226 /* fixme: we should update usage infos during cprop, instead of computing it again */
1227 cfg->comp_done &= ~MONO_COMP_SSA_DEF_USE;
1228 for (i = 0; i < cfg->num_varinfo; i++) {
1229 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1230 info->def = NULL;
1231 info->uses = NULL;
1232 }
1233 }
1234
1235 static inline void
1236 add_to_dce_worklist (MonoCompile *cfg, MonoMethodVar *var, MonoMethodVar *use, GList **wl)
1237 {
1238 GList *tmp;
1239
1240 *wl = g_list_prepend_mempool (cfg->mempool, *wl, use);
1241
1242 for (tmp = use->uses; tmp; tmp = tmp->next) {
1243 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1244 if (ui->inst == var->def) {
1245 /* from the mempool */
1246 use->uses = g_list_remove_link (use->uses, tmp);
1247 break;
1248 }
1249 }
1250 }
1251
1252 void
1253 mono_ssa_deadce (MonoCompile *cfg)
1254 {
1255 int i;
1256 GList *work_list;
1257
1258 g_assert (cfg->comp_done & MONO_COMP_SSA);
1259
1260 //printf ("DEADCE %s\n", mono_method_full_name (cfg->method, TRUE));
1261
1262 if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1263 mono_ssa_create_def_use (cfg);
1264
1265 mono_ssa_copyprop (cfg);
1266
1267 work_list = NULL;
1268 for (i = 0; i < cfg->num_varinfo; i++) {
1269 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1270 work_list = g_list_prepend_mempool (cfg->mempool, work_list, info);
1271 }
1272
1273 while (work_list) {
1274 MonoMethodVar *info = (MonoMethodVar *)work_list->data;
1275 work_list = g_list_remove_link (work_list, work_list);
1276
1277 /*
1278 * The second part of the condition happens often when PHI nodes have their dreg
1279 * as one of their arguments due to the fact that we use the original vars.
1280 */
1281 if (info->def && (!info->uses || ((info->uses->next == NULL) && (((MonoVarUsageInfo*)info->uses->data)->inst == info->def)))) {
1282 MonoInst *def = info->def;
1283
1284 /* Eliminating FMOVE could screw up the fp stack */
1285 if (MONO_IS_MOVE (def) && (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE))) {
1286 MonoInst *src_var = get_vreg_to_inst (cfg, def->sreg1);
1287 if (src_var && !(src_var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1288 add_to_dce_worklist (cfg, info, MONO_VARINFO (cfg, src_var->inst_c0), &work_list);
1289 def->opcode = OP_NOP;
1290 def->dreg = def->sreg1 = def->sreg2 = -1;
1291 info->reg = -1;
1292 } else if ((def->opcode == OP_ICONST) || (def->opcode == OP_I8CONST) || MONO_IS_ZERO (def)) {
1293 def->opcode = OP_NOP;
1294 def->dreg = def->sreg1 = def->sreg2 = -1;
1295 info->reg = -1;
1296 } else if (MONO_IS_PHI (def)) {
1297 int j;
1298 for (j = def->inst_phi_args [0]; j > 0; j--) {
1299 MonoMethodVar *u = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, def->inst_phi_args [j])->inst_c0);
1300 add_to_dce_worklist (cfg, info, u, &work_list);
1301 }
1302 def->opcode = OP_NOP;
1303 def->dreg = def->sreg1 = def->sreg2 = -1;
1304 info->reg = -1;
1305 }
1306 else if (def->opcode == OP_NOP) {
1307 }
1308 //else
1309 //mono_print_ins (def);
1310 }
1311
1312 }
1313 }
1314
1315 #if 0
1316 void
1317 mono_ssa_strength_reduction (MonoCompile *cfg)
1318 {
1319 MonoBasicBlock *bb;
1320 int i;
1321
1322 g_assert (cfg->comp_done & MONO_COMP_SSA);
1323 g_assert (cfg->comp_done & MONO_COMP_LOOPS);
1324 g_assert (cfg->comp_done & MONO_COMP_SSA_DEF_USE);
1325
1326 for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1327 GList *lp = bb->loop_blocks;
1328
1329 if (lp) {
1330 MonoBasicBlock *h = (MonoBasicBlock *)lp->data;
1331
1332 /* we only consider loops with 2 in bblocks */
1333 if (!h->in_count == 2)
1334 continue;
1335
1336 for (i = 0; i < cfg->num_varinfo; i++) {
1337 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1338
1339 if (info->def && info->def->ssa_op == MONO_SSA_STORE &&
1340 info->def->inst_i0->opcode == OP_LOCAL && g_list_find (lp, info->def_bb)) {
1341 MonoInst *v = info->def->inst_i1;
1342
1343
1344 printf ("FOUND %d in %s\n", info->idx, mono_method_full_name (cfg->method, TRUE));
1345 }
1346 }
1347 }
1348 }
1349 }
1350 #endif
1351
1352 #endif /* DISABLE_JIT */