2 * ssa.c: Static single assign form support for the JIT compiler.
5 * Dietmar Maurer (dietmar@ximian.com)
7 * (C) 2003 Ximian, Inc.
11 #include <mono/metadata/debug-helpers.h>
12 #include <mono/metadata/mempool.h>
13 #include <mono/metadata/mempool-internals.h>
22 #define USE_ORIGINAL_VARS
23 #define CREATE_PRUNED_SSA
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; \
40 unlink_target (MonoBasicBlock *bb, MonoBasicBlock *target)
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];
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];
60 unlink_unused_bblocks (MonoCompile *cfg)
65 g_assert (cfg->comp_done & MONO_COMP_REACHABILITY);
67 if (G_UNLIKELY (cfg->verbose_level > 1))
68 printf ("\nUNLINK UNUSED BBLOCKS:\n");
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;
77 for (i = 1; i < cfg->num_bblocks; i++) {
78 bb = cfg->bblocks [i];
80 if (!(bb->flags & BB_REACHABLE)) {
81 for (j = 0; j < bb->in_count; j++) {
82 unlink_target (bb->in_bb [j], bb);
84 for (j = 0; j < bb->out_count; j++) {
85 unlink_target (bb, bb->out_bb [j]);
87 if (G_UNLIKELY (cfg->verbose_level > 1))
88 printf ("\tUnlinked BB%d\n", bb->block_num);
95 * remove_bb_from_phis:
97 * Remove BB from the PHI statements in TARGET.
100 remove_bb_from_phis (MonoCompile *cfg, MonoBasicBlock *bb, MonoBasicBlock *target)
105 for (i = 0; i < target->in_count; i++) {
106 if (target->in_bb [i] == bb) {
110 g_assert (i < target->in_count);
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] --;
124 op_phi_to_move (int opcode)
136 g_assert_not_reached ();
143 record_use (MonoCompile *cfg, MonoInst *var, MonoBasicBlock *bb, MonoInst *ins)
146 MonoVarUsageInfo *ui = mono_mempool_alloc (cfg->mempool, sizeof (MonoVarUsageInfo));
148 info = MONO_VARINFO (cfg, var->inst_c0);
152 info->uses = g_list_prepend_mempool (cfg->mempool, info->uses, ui);
161 * mono_ssa_rename_vars:
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.
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)
170 MonoInst *ins, *new_var;
173 int stack_history_len = 0;
175 if (cfg->verbose_level >= 4)
176 printf ("\nRENAME VARS BLOCK %d:\n", bb->block_num);
178 /* First pass: Create new vars */
179 for (ins = bb->code; ins; ins = ins->next) {
180 const char *spec = INS_INFO (ins->opcode);
182 int sregs [MONO_MAX_SRC_REGS];
185 printf ("\tProcessing "); mono_print_ins (ins);
187 if (ins->opcode == OP_NOP)
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;
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);
204 record_use (cfg, var, bb, ins);
206 else if (G_UNLIKELY (!var && lvreg_stack [sregs [i]]))
207 sregs [i] = lvreg_stack [sregs [i]];
210 mono_inst_set_src_registers (ins, sregs);
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;
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);
223 record_use (cfg, var, bb, ins);
225 else if (G_UNLIKELY (!var && lvreg_stack [ins->dreg]))
226 ins->dreg = lvreg_stack [ins->dreg];
230 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
231 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
234 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
236 g_assert (idx < max_vars);
238 if (var->opcode == OP_ARG)
239 originals_used [idx] = TRUE;
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 ++;
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;
252 if (cfg->verbose_level >= 4)
253 printf (" R%d -> R%d\n", var->dreg, new_var->dreg);
255 stack [idx] = new_var;
257 ins->dreg = new_var->dreg;
262 originals_used [idx] = TRUE;
265 info = MONO_VARINFO (cfg, var->inst_c0);
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];
275 lvreg_defined [ins->dreg] = TRUE;
279 printf ("\tAfter processing "); mono_print_ins (ins);
284 /* Rename PHI arguments in succeeding bblocks */
285 for (i = 0; i < bb->out_count; i++) {
286 MonoBasicBlock *n = bb->out_bb [i];
288 for (j = 0; j < n->in_count; j++)
289 if (n->in_bb [j] == bb)
292 for (ins = n->code; ins; ins = ins->next) {
293 if (MONO_IS_PHI (ins)) {
296 new_var = stack [idx];
298 new_var = cfg->varinfo [idx];
300 printf ("FOUND PHI %d (%d, %d)\n", idx, j, new_var->inst_c0);
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);
308 /* The phi nodes are at the beginning of the bblock */
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);
320 for (i = stack_history_len - 1; i >= 0; i--) {
321 stack [stack_history [i].idx] = stack_history [i].var;
324 cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
328 mono_ssa_compute (MonoCompile *cfg)
330 int i, j, idx, bitsize;
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;
338 guint32 *lvreg_stack;
339 gboolean *lvreg_defined;
341 g_assert (!(cfg->comp_done & MONO_COMP_SSA));
343 g_assert (!cfg->disable_ssa);
345 if (cfg->verbose_level >= 4)
346 printf ("\nCOMPUTE SSA %d (R%d-)\n\n", cfg->num_varinfo, cfg->next_vreg);
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);
354 mono_compile_dominator_info (cfg, MONO_COMP_DOM | MONO_COMP_IDOM | MONO_COMP_DFRONTIER);
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);
359 for (i = 0; i < cfg->num_varinfo; ++i) {
360 vinfo [i].def_in = mono_bitset_mem_new (buf, cfg->num_bblocks, 0);
363 /* implicit reference at start */
364 if (cfg->varinfo [i]->opcode == OP_ARG)
365 mono_bitset_set_fast (vinfo [i].def_in, 0);
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)
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);
379 /* insert phi functions */
380 for (i = 0; i < cfg->num_varinfo; ++i) {
381 MonoInst *var = cfg->varinfo [i];
383 #if SIZEOF_REGISTER == 4
384 if (var->type == STACK_I8 && !COMPILE_LLVM (cfg))
387 if (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))
390 /* Most variables have only one definition */
391 if (mono_bitset_count (vinfo [i].def_in) <= 1)
394 set = mono_compile_iterated_dfrontier (cfg, vinfo [i].def_in);
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);
403 mono_bitset_foreach_bit (set, idx, cfg->num_bblocks) {
404 MonoBasicBlock *bb = cfg->bblocks [idx];
406 /* fixme: create pruned SSA? we would need liveness information for that */
408 if (bb == cfg->bb_exit && !COMPILE_LLVM (cfg))
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));
416 NEW_PHI (cfg, ins, i);
424 ins->opcode = OP_PHI;
427 ins->opcode = OP_FPHI;
430 ins->opcode = MONO_CLASS_IS_SIMD (cfg, var->klass) ? OP_XPHI : OP_VPHI;
434 if (var->inst_vtype->byref)
435 ins->klass = mono_defaults.int_class;
437 ins->klass = var->klass;
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;
443 for (j = 0; j < cfg->bblocks [idx]->in_count; ++j)
444 ins->inst_phi_args [j + 1] = -1;
446 ins->dreg = cfg->varinfo [i]->dreg;
448 mono_bblock_insert_before_ins (bb, bb->code, ins);
451 printf ("ADD PHI BB%d %s\n", cfg->bblocks [idx]->block_num, mono_method_full_name (cfg->method, TRUE));
462 stack = alloca (sizeof (MonoInst *) * cfg->num_varinfo);
463 memset (stack, 0, sizeof (MonoInst *) * cfg->num_varinfo);
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);
473 g_free (lvreg_stack);
474 g_free (lvreg_defined);
476 if (cfg->verbose_level >= 4)
477 printf ("\nEND COMPUTE SSA.\n\n");
479 cfg->comp_done |= MONO_COMP_SSA;
483 mono_ssa_remove (MonoCompile *cfg)
485 MonoInst *ins, *var, *move;
486 int bbindex, i, j, first;
488 g_assert (cfg->comp_done & MONO_COMP_SSA);
490 for (i = 0; i < cfg->num_bblocks; ++i) {
491 MonoBasicBlock *bb = cfg->bblocks [i];
493 if (cfg->verbose_level >= 4)
494 printf ("\nREMOVE SSA %d:\n", bb->block_num);
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);
501 /* Check for PHI nodes where all the inputs are the same */
502 first = ins->inst_phi_args [1];
504 for (j = 1; j < bb->in_count; ++j)
505 if (first != ins->inst_phi_args [j + 1])
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);
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];
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;
526 move->dreg = var->dreg;
528 mono_add_ins_to_end (pred, move);
532 ins->opcode = OP_NOP;
539 if (cfg->verbose_level >= 4) {
540 for (i = 0; i < cfg->num_bblocks; ++i) {
541 MonoBasicBlock *bb = cfg->bblocks [i];
543 mono_print_bb (bb, "AFTER REMOVE SSA:");
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.
554 for (bbindex = 0; bbindex < cfg->num_bblocks; ++bbindex) {
555 MonoBasicBlock *bb = cfg->bblocks [bbindex];
557 for (ins = bb->code; ins; ins = ins->next) {
558 const char *spec = INS_INFO (ins->opcode);
560 int sregs [MONO_MAX_SRC_REGS];
562 if (ins->opcode == OP_NOP)
565 if (spec [MONO_INST_DEST] != ' ') {
566 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
569 MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
572 * The third condition avoids coalescing with variables eliminated
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;
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]);
587 MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
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;
595 mono_inst_set_src_registers (ins, sregs);
599 for (i = 0; i < cfg->num_varinfo; ++i) {
600 MONO_VARINFO (cfg, i)->reg = -1;
603 if (cfg->comp_done & MONO_COMP_REACHABILITY)
604 unlink_unused_bblocks (cfg);
606 cfg->comp_done &= ~MONO_COMP_LIVENESS;
608 cfg->comp_done &= ~MONO_COMP_SSA;
612 mono_ssa_create_def_use (MonoCompile *cfg)
618 g_assert (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE));
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);
625 int sregs [MONO_MAX_SRC_REGS];
627 if (ins->opcode == OP_NOP)
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);
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);
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);
652 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
653 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
655 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
656 info = MONO_VARINFO (cfg, var->inst_c0);
664 cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
668 mono_ssa_copyprop (MonoCompile *cfg)
673 g_assert ((cfg->comp_done & MONO_COMP_SSA_DEF_USE));
675 for (index = 0; index < cfg->num_varinfo; ++index) {
676 MonoInst *var = cfg->varinfo [index];
677 MonoMethodVar *info = MONO_VARINFO (cfg, index);
679 if (info->def && (MONO_IS_MOVE (info->def))) {
680 MonoInst *var2 = get_vreg_to_inst (cfg, info->def->sreg1);
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;
689 MonoVarUsageInfo *u = (MonoVarUsageInfo*)l->data;
690 MonoInst *ins = u->inst;
691 GList *next = l->next;
693 int sregs [MONO_MAX_SRC_REGS];
695 num_sregs = mono_inst_get_src_registers (ins, sregs);
696 for (i = 0; i < num_sregs; ++i) {
697 if (sregs [i] == dreg)
701 g_assert (sregs [i] == dreg);
703 mono_inst_set_src_registers (ins, sregs);
704 } else if (MONO_IS_STORE_MEMBASE (ins) && ins->dreg == dreg) {
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)
713 ins->inst_phi_args [i] = sreg1;
716 g_assert_not_reached ();
718 record_use (cfg, var2, u->bb, ins);
728 if (cfg->verbose_level >= 4) {
731 for (bb = cfg->bb_entry; bb; bb = bb->next_bb)
732 mono_print_bb (bb, "AFTER SSA COPYPROP");
737 evaluate_ins (MonoCompile *cfg, MonoInst *ins, MonoInst **res, MonoInst **carray)
739 MonoInst *args [MONO_MAX_SRC_REGS];
740 int rs [MONO_MAX_SRC_REGS];
742 gboolean const_args = TRUE;
743 const char *spec = INS_INFO (ins->opcode);
745 int sregs [MONO_MAX_SRC_REGS];
747 /* Short-circuit this */
748 if (ins->opcode == OP_ICONST) {
753 if (ins->opcode == OP_NOP)
756 num_sregs = mono_inst_get_src_registers (ins, sregs);
757 for (i = 0; i < MONO_MAX_SRC_REGS; ++i)
759 for (i = 0; i < num_sregs; ++i) {
760 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
763 args [i] = carray [sregs [i]];
766 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
767 rs [i] = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
774 if (num_sregs > 0 && const_args) {
775 g_assert (num_sregs <= 2);
776 if ((spec [MONO_INST_DEST] != ' ') && carray [ins->dreg]) {
778 *res = carray [ins->dreg];
781 c0 = mono_constant_fold_ins (cfg, ins, args [0], args [1], FALSE);
783 if (G_UNLIKELY (cfg->verbose_level > 1)) {
784 printf ("\t cfold -> ");
791 /* Can't cfold this ins */
797 for (i = 0; i < num_sregs; ++i) {
805 change_varstate (MonoCompile *cfg, GList **cvars, MonoMethodVar *info, int state, MonoInst *c0, MonoInst **carray)
807 if (info->cpstate >= state)
810 info->cpstate = state;
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);
818 carray [cfg->varinfo [info->idx]->dreg] = c0;
820 if (!g_list_find (*cvars, info)) {
821 *cvars = g_list_prepend (*cvars, info);
826 add_cprop_bb (MonoCompile *cfg, MonoBasicBlock *bb, GList **bblist)
828 if (G_UNLIKELY (cfg->verbose_level > 1))
829 printf ("\tAdd BB%d to worklist\n", bb->block_num);
831 if (!(bb->flags & BB_REACHABLE)) {
832 bb->flags |= BB_REACHABLE;
833 *bblist = g_list_prepend (*bblist, bb);
838 visit_inst (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, GList **cvars, GList **bblist, MonoInst **carray)
840 const char *spec = INS_INFO (ins->opcode);
842 if (ins->opcode == OP_NOP)
845 if (cfg->verbose_level > 1)
846 mono_print_ins (ins);
848 /* FIXME: Support longs/floats */
849 /* FIXME: Work on vregs as well */
851 if (MONO_IS_PHI (ins)) {
852 MonoMethodVar *info = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, ins->dreg)->inst_c0);
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;
861 if (mv->def_bb && !(mv->def_bb->flags & BB_REACHABLE))
864 if (!mv->def || !src || mv->cpstate == 2) {
865 change_varstate (cfg, cvars, info, 2, NULL, carray);
869 if (mv->cpstate == 0)
872 g_assert (carray [var->dreg]);
875 c0 = carray [var->dreg];
878 if (c0->opcode != OP_ICONST) {
879 change_varstate (cfg, cvars, info, 2, NULL, carray);
883 if (carray [var->dreg]->inst_c0 != c0->inst_c0) {
884 change_varstate (cfg, cvars, info, 2, NULL, carray);
889 if (c0 && info->cpstate < 1) {
890 change_varstate (cfg, cvars, info, 1, c0, carray);
892 g_assert (c0->opcode == OP_ICONST);
895 else if (!MONO_IS_STORE_MEMBASE (ins) && ((spec [MONO_INST_SRC1] != ' ') || (spec [MONO_INST_SRC2] != ' ') || (spec [MONO_INST_DEST] != ' '))) {
899 if (spec [MONO_INST_DEST] != ' ')
900 var = get_vreg_to_inst (cfg, ins->dreg);
905 state = evaluate_ins (cfg, ins, &c0, carray);
907 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
908 MonoMethodVar *info = MONO_VARINFO (cfg, var->inst_c0);
910 if (info->cpstate < 2) {
912 change_varstate (cfg, cvars, info, 1, c0, carray);
914 change_varstate (cfg, cvars, info, 2, NULL, carray);
917 else if (!var && (ins->dreg != -1)) {
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.
925 carray [ins->dreg] = c0;
927 if (carray [ins->dreg]) {
929 * The state of the vreg changed from constant to non-constant
930 * -> need to rescan the whole bblock.
932 carray [ins->dreg] = NULL;
933 /* FIXME: Speed this up */
935 if (!g_list_find (*bblist, bb))
936 *bblist = g_list_prepend (*bblist, bb);
941 if (MONO_IS_JUMP_TABLE (ins)) {
943 MonoJumpInfoBBTable *table = MONO_JUMP_TABLE_FROM_INS (ins);
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);
954 g_assert (ins->next->opcode == OP_PADD);
955 g_assert (ins->next->sreg1 == ins->dreg);
957 if (carray [ins->next->sreg2]) {
958 #if SIZEOF_REGISTER == 8
959 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
961 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
963 if ((idx < 0) || (idx >= table->table_size))
964 /* Out-of-range, no branch is executed */
967 if (table->table [idx])
968 add_cprop_bb (cfg, table->table [idx], bblist);
971 for (i = 0; i < table->table_size; i++)
972 if (table->table [i])
973 add_cprop_bb (cfg, table->table [i], bblist);
977 if (ins->opcode == OP_SWITCH) {
979 MonoJumpInfoBBTable *table = ins->inst_p0;
981 for (i = 0; i < table->table_size; i++)
982 if (table->table [i])
983 add_cprop_bb (cfg, table->table [i], bblist);
986 /* Handle COMPARE+BRCOND pairs */
987 if (ins->next && MONO_IS_COND_BRANCH_OP (ins->next)) {
989 g_assert (c0->opcode == OP_ICONST);
992 ins->next->flags |= MONO_INST_CFOLD_TAKEN;
994 ins->next->flags |= MONO_INST_CFOLD_NOT_TAKEN;
997 ins->next->flags &= ~(MONO_INST_CFOLD_TAKEN | MONO_INST_CFOLD_NOT_TAKEN);
1000 visit_inst (cfg, bb, ins->next, cvars, bblist, carray);
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);
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);
1021 * Replace INS with its constant value, if it exists
1024 fold_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **carray)
1026 const char *spec = INS_INFO (ins->opcode);
1028 int num_sregs = mono_inst_get_num_src_registers (ins);
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 */
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;
1046 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
1047 ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
1050 /* FIXME: Handle 3 op insns */
1053 if (MONO_IS_JUMP_TABLE (ins)) {
1055 MonoJumpInfoBBTable *table = MONO_JUMP_TABLE_FROM_INS (ins);
1057 if (!ins->next || ins->next->opcode != OP_PADD) {
1058 /* The PADD was optimized away */
1059 /* FIXME: handle this as well */
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);
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;
1072 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
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]);
1083 NULLIFY_INS (ins->next);
1084 NULLIFY_INS (ins->next->next);
1085 if (ins->next->next->next)
1086 NULLIFY_INS (ins->next->next->next);
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);
1100 if (G_UNLIKELY (cfg->verbose_level > 1)) {
1101 printf ("\tcfold on ");
1102 mono_print_ins (ins);
1105 /* Unlink target bblocks */
1106 for (i = 0; i < table->table_size; ++i) {
1108 remove_bb_from_phis (cfg, bb, table->table [i]);
1109 mono_unlink_bblock (cfg, bb, table->table [i]);
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;
1118 /* Nullify the other instructions */
1120 NULLIFY_INS (ins->next);
1121 NULLIFY_INS (ins->next->next);
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;
1141 mono_ssa_cprop (MonoCompile *cfg)
1145 GList *bblock_list, *cvars;
1148 //printf ("SIMPLE OPTS BB%d %s\n", bb->block_num, mono_method_full_name (cfg->method, TRUE));
1150 carray = g_new0 (MonoInst*, cfg->next_vreg);
1152 if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1153 mono_ssa_create_def_use (cfg);
1155 bblock_list = g_list_prepend (NULL, cfg->bb_entry);
1156 cfg->bb_entry->flags |= BB_REACHABLE;
1158 memset (carray, 0, sizeof (MonoInst *) * cfg->num_varinfo);
1160 for (i = 0; i < cfg->num_varinfo; i++) {
1161 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1166 for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1168 * FIXME: This should be bb->flags & BB_FLAG_EXCEPTION_HANDLER, but
1169 * that would still allow unreachable try's to be removed.
1172 add_cprop_bb (cfg, bb, &bblock_list);
1177 while (bblock_list) {
1180 bb = (MonoBasicBlock *)bblock_list->data;
1182 bblock_list = g_list_delete_link (bblock_list, bblock_list);
1184 g_assert (bb->flags & BB_REACHABLE);
1187 * Some bblocks are linked to 2 others even through they fall through to the
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);
1195 if (cfg->verbose_level > 1)
1196 printf ("\nSSA CONSPROP BB%d:\n", bb->block_num);
1198 for (inst = bb->code; inst; inst = inst->next) {
1199 visit_inst (cfg, bb, inst, &cvars, &bblock_list, carray);
1203 MonoMethodVar *info = (MonoMethodVar *)cvars->data;
1204 cvars = g_list_delete_link (cvars, cvars);
1206 for (tmp = info->uses; tmp; tmp = tmp->next) {
1207 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1208 if (!(ui->bb->flags & BB_REACHABLE))
1210 visit_inst (cfg, ui->bb, ui->inst, &cvars, &bblock_list, carray);
1215 for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1217 for (inst = bb->code; inst; inst = inst->next) {
1218 fold_ins (cfg, bb, inst, carray);
1224 cfg->comp_done |= MONO_COMP_REACHABILITY;
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);
1236 add_to_dce_worklist (MonoCompile *cfg, MonoMethodVar *var, MonoMethodVar *use, GList **wl)
1240 *wl = g_list_prepend_mempool (cfg->mempool, *wl, use);
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);
1253 mono_ssa_deadce (MonoCompile *cfg)
1258 g_assert (cfg->comp_done & MONO_COMP_SSA);
1260 //printf ("DEADCE %s\n", mono_method_full_name (cfg->method, TRUE));
1262 if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1263 mono_ssa_create_def_use (cfg);
1265 mono_ssa_copyprop (cfg);
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);
1274 MonoMethodVar *info = (MonoMethodVar *)work_list->data;
1275 work_list = g_list_remove_link (work_list, work_list);
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.
1281 if (info->def && (!info->uses || ((info->uses->next == NULL) && (((MonoVarUsageInfo*)info->uses->data)->inst == info->def)))) {
1282 MonoInst *def = info->def;
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;
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;
1296 } else if (MONO_IS_PHI (def)) {
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);
1302 def->opcode = OP_NOP;
1303 def->dreg = def->sreg1 = def->sreg2 = -1;
1306 else if (def->opcode == OP_NOP) {
1309 //mono_print_ins (def);
1317 mono_ssa_strength_reduction (MonoCompile *cfg)
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);
1326 for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1327 GList *lp = bb->loop_blocks;
1330 MonoBasicBlock *h = (MonoBasicBlock *)lp->data;
1332 /* we only consider loops with 2 in bblocks */
1333 if (!h->in_count == 2)
1336 for (i = 0; i < cfg->num_varinfo; i++) {
1337 MonoMethodVar *info = MONO_VARINFO (cfg, i);
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;
1344 printf ("FOUND %d in %s\n", info->idx, mono_method_full_name (cfg->method, TRUE));
1352 #endif /* DISABLE_JIT */