X-Git-Url: http://wien.tomnetworks.com/gitweb/?a=blobdiff_plain;f=mono%2Fmini%2Fbranch-opts.c;h=bd2b2d804581152078c8cf1f68904e6b2711cc26;hb=53f83c9f56f372f4e801227fc5d60f0f4b8d1c8b;hp=f57180b61e4d4bb8a0459ac8628e088cd5033dcd;hpb=53e266903ec6b2d822cf5b0c566f6374df5307a4;p=mono.git diff --git a/mono/mini/branch-opts.c b/mono/mini/branch-opts.c index f57180b61e4..bd2b2d80458 100644 --- a/mono/mini/branch-opts.c +++ b/mono/mini/branch-opts.c @@ -5,10 +5,25 @@ * Patrik Torstensson (Patrik.Torstesson at gmail.com) * * (C) 2005 Ximian, Inc. http://www.ximian.com + * Copyright 2011 Xamarin Inc. http://www.xamarin.com */ #include "mini.h" + +#ifndef DISABLE_JIT - /* + +/* + * Returns true if @bb is a basic block which falls through the next block. + * TODO verify if it helps to check if the bb last ins is a branch to its successor. + */ +static gboolean +mono_bb_is_fall_through (MonoCompile *cfg, MonoBasicBlock *bb) +{ + return bb->next_bb && bb->next_bb->region == bb->region && /*fall throught between regions is not really interesting or useful*/ + (bb->last_ins == NULL || !MONO_IS_BRANCH_OP (bb->last_ins)); /*and the last op can't be a branch too*/ +} + +/* * Used by the arch code to replace the exception handling * with a direct branch. This is safe to do if the * exception object isn't used, no rethrow statement and @@ -18,8 +33,7 @@ MonoInst * mono_branch_optimize_exception_target (MonoCompile *cfg, MonoBasicBlock *bb, const char * exname) { - MonoMethod *method = cfg->method; - MonoMethodHeader *header = mono_method_get_header (method); + MonoMethodHeader *header = cfg->header; MonoExceptionClause *clause; MonoClass *exclass; int i; @@ -43,7 +57,7 @@ mono_branch_optimize_exception_target (MonoCompile *cfg, MonoBasicBlock *bb, con * Flag is set during method_to_ir due to * pop-op is optmized away in codegen (burg). */ - tbb = g_hash_table_lookup (cfg->bb_hash, header->code + clause->handler_offset); + tbb = cfg->cil_offset_to_bb [clause->handler_offset]; if (tbb && tbb->flags & BB_EXCEPTION_DEAD_OBJ && !(tbb->flags & BB_EXCEPTION_UNSAFE)) { MonoBasicBlock *targetbb = tbb; gboolean unsafe = FALSE; @@ -68,7 +82,7 @@ mono_branch_optimize_exception_target (MonoCompile *cfg, MonoBasicBlock *bb, con /* Create dummy inst to allow easier integration in * arch dependent code (opcode ignored) */ - MONO_INST_NEW (cfg, jump, CEE_BR); + MONO_INST_NEW (cfg, jump, OP_BR); /* Allocate memory for our branch target */ jump->inst_i1 = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoInst)); @@ -80,6 +94,9 @@ mono_branch_optimize_exception_target (MonoCompile *cfg, MonoBasicBlock *bb, con return jump; } + return NULL; + } else { + /* Branching to an outer clause could skip inner clauses */ return NULL; } } else { @@ -92,3 +109,1352 @@ mono_branch_optimize_exception_target (MonoCompile *cfg, MonoBasicBlock *bb, con return NULL; } +static const int int_cmov_opcodes [] = { + OP_CMOV_IEQ, + OP_CMOV_INE_UN, + OP_CMOV_ILE, + OP_CMOV_IGE, + OP_CMOV_ILT, + OP_CMOV_IGT, + OP_CMOV_ILE_UN, + OP_CMOV_IGE_UN, + OP_CMOV_ILT_UN, + OP_CMOV_IGT_UN +}; + +static const int long_cmov_opcodes [] = { + OP_CMOV_LEQ, + OP_CMOV_LNE_UN, + OP_CMOV_LLE, + OP_CMOV_LGE, + OP_CMOV_LLT, + OP_CMOV_LGT, + OP_CMOV_LLE_UN, + OP_CMOV_LGE_UN, + OP_CMOV_LLT_UN, + OP_CMOV_LGT_UN +}; + +static G_GNUC_UNUSED int +br_to_br_un (int opcode) +{ + switch (opcode) { + case OP_IBGT: + return OP_IBGT_UN; + break; + case OP_IBLE: + return OP_IBLE_UN; + break; + case OP_LBGT: + return OP_LBGT_UN; + break; + case OP_LBLE: + return OP_LBLE_UN; + break; + default: + g_assert_not_reached (); + return -1; + } +} + +/** + * mono_replace_ins: + * + * Replace INS with its decomposition which is stored in a series of bblocks starting + * at FIRST_BB and ending at LAST_BB. On enter, PREV points to the predecessor of INS. + * On return, it will be set to the last ins of the decomposition. + */ +void +mono_replace_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **prev, MonoBasicBlock *first_bb, MonoBasicBlock *last_bb) +{ + MonoInst *next = ins->next; + + if (next && next->opcode == OP_NOP) { + /* Avoid NOPs following branches */ + ins->next = next->next; + next = next->next; + } + + if (first_bb == last_bb) { + /* + * Only one replacement bb, merge the code into + * the current bb. + */ + + /* Delete links between the first_bb and its successors */ + while (first_bb->out_count) + mono_unlink_bblock (cfg, first_bb, first_bb->out_bb [0]); + + /* Head */ + if (*prev) { + (*prev)->next = first_bb->code; + first_bb->code->prev = (*prev); + } else { + bb->code = first_bb->code; + } + + /* Tail */ + last_bb->last_ins->next = next; + if (next) + next->prev = last_bb->last_ins; + else + bb->last_ins = last_bb->last_ins; + *prev = last_bb->last_ins; + bb->has_array_access |= first_bb->has_array_access; + } else { + int i, count; + MonoBasicBlock **tmp_bblocks, *tmp; + MonoInst *last; + + /* Multiple BBs */ + + /* Set region */ + for (tmp = first_bb; tmp; tmp = tmp->next_bb) + tmp->region = bb->region; + + /* Split the original bb */ + if (ins->next) + ins->next->prev = NULL; + ins->next = NULL; + bb->last_ins = ins; + + /* Merge the second part of the original bb into the last bb */ + if (last_bb->last_ins) { + last_bb->last_ins->next = next; + if (next) + next->prev = last_bb->last_ins; + } else { + last_bb->code = next; + } + last_bb->has_array_access |= bb->has_array_access; + + if (next) { + for (last = next; last->next != NULL; last = last->next) + ; + last_bb->last_ins = last; + } + + for (i = 0; i < bb->out_count; ++i) + mono_link_bblock (cfg, last_bb, bb->out_bb [i]); + + /* Merge the first (dummy) bb to the original bb */ + if (*prev) { + (*prev)->next = first_bb->code; + first_bb->code->prev = (*prev); + } else { + bb->code = first_bb->code; + } + bb->last_ins = first_bb->last_ins; + bb->has_array_access |= first_bb->has_array_access; + + /* Delete the links between the original bb and its successors */ + tmp_bblocks = bb->out_bb; + count = bb->out_count; + for (i = 0; i < count; ++i) + mono_unlink_bblock (cfg, bb, tmp_bblocks [i]); + + /* Add links between the original bb and the first_bb's successors */ + for (i = 0; i < first_bb->out_count; ++i) { + MonoBasicBlock *out_bb = first_bb->out_bb [i]; + + mono_link_bblock (cfg, bb, out_bb); + } + /* Delete links between the first_bb and its successors */ + for (i = 0; i < bb->out_count; ++i) { + MonoBasicBlock *out_bb = bb->out_bb [i]; + + mono_unlink_bblock (cfg, first_bb, out_bb); + } + last_bb->next_bb = bb->next_bb; + bb->next_bb = first_bb->next_bb; + + *prev = NULL; + } +} + +void +mono_if_conversion (MonoCompile *cfg) +{ +#ifdef MONO_ARCH_HAVE_CMOV_OPS + MonoBasicBlock *bb; + gboolean changed = FALSE; + + if (!(cfg->opt & MONO_OPT_CMOV)) + return; + + // FIXME: Make this work with extended bblocks + + /* + * This pass requires somewhat optimized IR code so it should be run after + * local cprop/deadce. Also, it should be run before dominator computation, since + * it changes control flow. + */ + for (bb = cfg->bb_entry; bb; bb = bb->next_bb) { + MonoBasicBlock *bb1, *bb2; + + restart: + /* Look for the IR code generated from cond ? a : b + * which is: + * BB: + * b [BB1BB2] + * BB1: + * <- + * br BB3 + * BB2: + * <- + * br BB3 + */ + if (!(bb->out_count == 2 && !bb->extended)) + continue; + + bb1 = bb->out_bb [0]; + bb2 = bb->out_bb [1]; + + if (bb1->in_count == 1 && bb2->in_count == 1 && bb1->out_count == 1 && bb2->out_count == 1 && bb1->out_bb [0] == bb2->out_bb [0]) { + MonoInst *compare, *branch, *ins1, *ins2, *cmov, *move, *tmp; + MonoBasicBlock *true_bb, *false_bb; + gboolean simple, ret; + int dreg, tmp_reg; + CompType comp_type; + + if (bb->last_ins && (bb->last_ins->opcode == OP_BR_REG || bb->last_ins->opcode == OP_BR)) + continue; + + /* Find the compare instruction */ + if (!bb->last_ins || !bb->last_ins->prev) + continue; + branch = bb->last_ins; + compare = branch->prev; + + if (!MONO_IS_COND_BRANCH_OP (branch)) + /* This can happen if a cond branch is optimized away */ + continue; + + true_bb = branch->inst_true_bb; + false_bb = branch->inst_false_bb; + + /* + * Check that bb1 and bb2 are 'simple' and both assign to the same + * variable. + */ + /* FIXME: Get rid of the nops earlier */ + ins1 = true_bb->code; + while (ins1 && ins1->opcode == OP_NOP) + ins1 = ins1->next; + ins2 = false_bb->code; + while (ins2 && ins2->opcode == OP_NOP) + ins2 = ins2->next; + if (!(ins1 && ins2 && ins1->dreg == ins2->dreg && ins1->dreg != -1)) + continue; + + simple = TRUE; + for (tmp = ins1->next; tmp; tmp = tmp->next) + if (!((tmp->opcode == OP_NOP) || (tmp->opcode == OP_BR))) + simple = FALSE; + + for (tmp = ins2->next; tmp; tmp = tmp->next) + if (!((tmp->opcode == OP_NOP) || (tmp->opcode == OP_BR))) + simple = FALSE; + + if (!simple) + continue; + + /* We move ins1/ins2 before the compare so they should have no side effect */ + if (!(MONO_INS_HAS_NO_SIDE_EFFECT (ins1) && MONO_INS_HAS_NO_SIDE_EFFECT (ins2))) + continue; + + /* Moving ins1/ins2 could change the comparison */ + /* FIXME: */ + if (!((compare->sreg1 != ins1->dreg) && (compare->sreg2 != ins1->dreg))) + continue; + + /* FIXME: */ + comp_type = mono_opcode_to_type (branch->opcode, compare->opcode); + if (!((comp_type == CMP_TYPE_I) || (comp_type == CMP_TYPE_L))) + continue; + + /* FIXME: */ + /* ins->type might not be set */ + if (INS_INFO (ins1->opcode) [MONO_INST_DEST] != 'i') + continue; + + if (cfg->verbose_level > 2) { + printf ("\tBranch -> CMove optimization in BB%d on\n", bb->block_num); + printf ("\t\t"); mono_print_ins (compare); + printf ("\t\t"); mono_print_ins (compare->next); + printf ("\t\t"); mono_print_ins (ins1); + printf ("\t\t"); mono_print_ins (ins2); + } + + changed = TRUE; + + //printf ("HIT!\n"); + + /* Assignments to the return register must remain at the end of bbs */ + if (cfg->ret) + ret = ins1->dreg == cfg->ret->dreg; + else + ret = FALSE; + + tmp_reg = mono_alloc_dreg (cfg, STACK_I4); + dreg = ins1->dreg; + + /* Rewrite ins1 to emit to tmp_reg */ + ins1->dreg = tmp_reg; + + if (ret) { + dreg = mono_alloc_dreg (cfg, STACK_I4); + ins2->dreg = dreg; + } + + /* Remove ins1/ins2 from bb1/bb2 */ + MONO_REMOVE_INS (true_bb, ins1); + MONO_REMOVE_INS (false_bb, ins2); + + /* Move ins1 and ins2 before the comparison */ + /* ins1 comes first to avoid ins1 overwriting an argument of ins2 */ + mono_bblock_insert_before_ins (bb, compare, ins2); + mono_bblock_insert_before_ins (bb, ins2, ins1); + + /* Add cmov instruction */ + MONO_INST_NEW (cfg, cmov, OP_NOP); + cmov->dreg = dreg; + cmov->sreg1 = dreg; + cmov->sreg2 = tmp_reg; + switch (mono_opcode_to_type (branch->opcode, compare->opcode)) { + case CMP_TYPE_I: + cmov->opcode = int_cmov_opcodes [mono_opcode_to_cond (branch->opcode)]; + break; + case CMP_TYPE_L: + cmov->opcode = long_cmov_opcodes [mono_opcode_to_cond (branch->opcode)]; + break; + default: + g_assert_not_reached (); + } + mono_bblock_insert_after_ins (bb, compare, cmov); + + if (ret) { + /* Add an extra move */ + MONO_INST_NEW (cfg, move, OP_MOVE); + move->dreg = cfg->ret->dreg; + move->sreg1 = dreg; + mono_bblock_insert_after_ins (bb, cmov, move); + } + + /* Rewrite the branch */ + branch->opcode = OP_BR; + branch->inst_target_bb = true_bb->out_bb [0]; + mono_link_bblock (cfg, bb, branch->inst_target_bb); + + /* Reorder bblocks */ + mono_unlink_bblock (cfg, bb, true_bb); + mono_unlink_bblock (cfg, bb, false_bb); + mono_unlink_bblock (cfg, true_bb, true_bb->out_bb [0]); + mono_unlink_bblock (cfg, false_bb, false_bb->out_bb [0]); + mono_remove_bblock (cfg, true_bb); + mono_remove_bblock (cfg, false_bb); + + /* Merge bb and its successor if possible */ + if ((bb->out_bb [0]->in_count == 1) && (bb->out_bb [0] != cfg->bb_exit) && + (bb->region == bb->out_bb [0]->region)) { + mono_merge_basic_blocks (cfg, bb, bb->out_bb [0]); + goto restart; + } + } + + /* Look for the IR code generated from if (cond) <- + * which is: + * BB: + * b [BB1BB2] + * BB1: + * <- + * br BB2 + */ + + if ((bb2->in_count == 1 && bb2->out_count == 1 && bb2->out_bb [0] == bb1) || + (bb1->in_count == 1 && bb1->out_count == 1 && bb1->out_bb [0] == bb2)) { + MonoInst *compare, *branch, *ins1, *cmov, *tmp; + gboolean simple; + int dreg, tmp_reg; + CompType comp_type; + CompRelation cond; + MonoBasicBlock *next_bb, *code_bb; + + /* code_bb is the bblock containing code, next_bb is the successor bblock */ + if (bb2->in_count == 1 && bb2->out_count == 1 && bb2->out_bb [0] == bb1) { + code_bb = bb2; + next_bb = bb1; + } else { + code_bb = bb1; + next_bb = bb2; + } + + ins1 = code_bb->code; + + if (!ins1) + continue; + + /* Check that code_bb is simple */ + simple = TRUE; + for (tmp = ins1->next; tmp; tmp = tmp->next) + if (!((tmp->opcode == OP_NOP) || (tmp->opcode == OP_BR))) + simple = FALSE; + + if (!simple) + continue; + + /* We move ins1 before the compare so it should have no side effect */ + if (!MONO_INS_HAS_NO_SIDE_EFFECT (ins1)) + continue; + + if (bb->last_ins && bb->last_ins->opcode == OP_BR_REG) + continue; + + /* Find the compare instruction */ + + if (!bb->last_ins || !bb->last_ins->prev) + continue; + branch = bb->last_ins; + compare = branch->prev; + + if (!MONO_IS_COND_BRANCH_OP (branch)) + /* This can happen if a cond branch is optimized away */ + continue; + + /* FIXME: */ + comp_type = mono_opcode_to_type (branch->opcode, compare->opcode); + if (!((comp_type == CMP_TYPE_I) || (comp_type == CMP_TYPE_L))) + continue; + + /* FIXME: */ + /* ins->type might not be set */ + if (INS_INFO (ins1->opcode) [MONO_INST_DEST] != 'i') + continue; + + /* FIXME: */ + if (cfg->ret && ins1->dreg == cfg->ret->dreg) + continue; + + if (!(cfg->opt & MONO_OPT_DEADCE)) + /* + * It is possible that dreg is never set before, so we can't use + * it as an sreg of the cmov instruction (#582322). + */ + continue; + + if (cfg->verbose_level > 2) { + printf ("\tBranch -> CMove optimization (2) in BB%d on\n", bb->block_num); + printf ("\t\t"); mono_print_ins (compare); + printf ("\t\t"); mono_print_ins (compare->next); + printf ("\t\t"); mono_print_ins (ins1); + } + + changed = TRUE; + + //printf ("HIT!\n"); + + tmp_reg = mono_alloc_dreg (cfg, STACK_I4); + dreg = ins1->dreg; + + /* Rewrite ins1 to emit to tmp_reg */ + ins1->dreg = tmp_reg; + + /* Remove ins1 from code_bb */ + MONO_REMOVE_INS (code_bb, ins1); + + /* Move ins1 before the comparison */ + mono_bblock_insert_before_ins (bb, compare, ins1); + + /* Add cmov instruction */ + MONO_INST_NEW (cfg, cmov, OP_NOP); + cmov->dreg = dreg; + cmov->sreg1 = dreg; + cmov->sreg2 = tmp_reg; + cond = mono_opcode_to_cond (branch->opcode); + if (branch->inst_false_bb == code_bb) + cond = mono_negate_cond (cond); + switch (mono_opcode_to_type (branch->opcode, compare->opcode)) { + case CMP_TYPE_I: + cmov->opcode = int_cmov_opcodes [cond]; + break; + case CMP_TYPE_L: + cmov->opcode = long_cmov_opcodes [cond]; + break; + default: + g_assert_not_reached (); + } + mono_bblock_insert_after_ins (bb, compare, cmov); + + /* Rewrite the branch */ + branch->opcode = OP_BR; + branch->inst_target_bb = next_bb; + mono_link_bblock (cfg, bb, branch->inst_target_bb); + + /* Nullify the branch at the end of code_bb */ + if (code_bb->code) { + branch = code_bb->code; + MONO_DELETE_INS (code_bb, branch); + } + + /* Reorder bblocks */ + mono_unlink_bblock (cfg, bb, code_bb); + mono_unlink_bblock (cfg, code_bb, next_bb); + + /* Merge bb and its successor if possible */ + if ((bb->out_bb [0]->in_count == 1) && (bb->out_bb [0] != cfg->bb_exit) && + (bb->region == bb->out_bb [0]->region)) { + mono_merge_basic_blocks (cfg, bb, bb->out_bb [0]); + + /* + * bbn might have fallen through to the next bb without a branch, + * have to add one now (#474718). + * FIXME: Maybe need to do this more generally in + * merge_basic_blocks () ? + */ + if (!(bb->last_ins && MONO_IS_BRANCH_OP (bb->last_ins)) && bb->out_count) { + MONO_INST_NEW (cfg, ins1, OP_BR); + ins1->inst_target_bb = bb->out_bb [0]; + MONO_ADD_INS (bb, ins1); + } + goto restart; + } + } + } + + /* + * Optimize checks like: if (v < 0 || v > limit) by changing then to unsigned + * compares. This isn't really if conversion, but it easier to do here than in + * optimize_branches () since the IR is already optimized. + */ + for (bb = cfg->bb_entry; bb; bb = bb->next_bb) { + MonoBasicBlock *bb1, *bb2, *true_bb, *false_bb, *next_bb; + MonoInst *branch1, *branch2, *compare1, *ins; + + /* Look for the IR code generated from if ( < 0 || v > ) + * after branch opts which is: + * BB: + * icompare_imm R [0] + * int_blt [BB1BB2] + * BB2: + * icompare_imm R [] + * int_ble [BB3BB1] + */ + if (!(bb->out_count == 2 && !bb->extended)) + continue; + + bb1 = bb->out_bb [0]; + bb2 = bb->out_bb [1]; + + // FIXME: Add more cases + + /* Check structure */ + if (!(bb1->in_count == 2 && bb1->in_bb [0] == bb && bb1->in_bb [1] == bb2 && bb2->in_count == 1 && bb2->out_count == 2)) + continue; + + next_bb = bb2; + + /* Check first branch */ + branch1 = bb->last_ins; + if (!(branch1 && ((branch1->opcode == OP_IBLT) || (branch1->opcode == OP_LBLT)) && (branch1->inst_false_bb == next_bb))) + continue; + + true_bb = branch1->inst_true_bb; + + /* Check second branch */ + branch2 = next_bb->last_ins; + if (!branch2) + continue; + + /* mcs sometimes generates inverted branches */ + if (((branch2->opcode == OP_IBGT) || (branch2->opcode == OP_LBGT)) && branch2->inst_true_bb == branch1->inst_true_bb) + false_bb = branch2->inst_false_bb; + else if (((branch2->opcode == OP_IBLE) || (branch2->opcode == OP_LBLE)) && branch2->inst_false_bb == branch1->inst_true_bb) + false_bb = branch2->inst_true_bb; + else + continue; + + /* Check first compare */ + compare1 = bb->last_ins->prev; + if (!(compare1 && ((compare1->opcode == OP_ICOMPARE_IMM) || (compare1->opcode == OP_LCOMPARE_IMM)) && compare1->inst_imm == 0)) + continue; + + /* Check second bblock */ + ins = next_bb->code; + if (!ins) + continue; + if (((ins->opcode == OP_ICOMPARE_IMM) || (ins->opcode == OP_LCOMPARE_IMM)) && ins->sreg1 == compare1->sreg1 && ins->next == branch2) { + /* The second arg must be positive */ + if (ins->inst_imm < 0) + continue; + } else if (((ins->opcode == OP_LDLEN) || (ins->opcode == OP_STRLEN)) && ins->dreg != compare1->sreg1 && ins->next && ins->next->opcode == OP_ICOMPARE && ins->next->sreg1 == compare1->sreg1 && ins->next->sreg2 == ins->dreg && ins->next->next == branch2) { + /* Another common case: if (index < 0 || index > arr.Length) */ + } else { + continue; + } + + if (cfg->verbose_level > 2) { + printf ("\tSigned->unsigned compare optimization in BB%d on\n", bb->block_num); + printf ("\t\t"); mono_print_ins (compare1); + printf ("\t\t"); mono_print_ins (compare1->next); + printf ("\t\t"); mono_print_ins (ins); + } + + /* Rewrite the first compare+branch */ + MONO_DELETE_INS (bb, compare1); + branch1->opcode = OP_BR; + mono_unlink_bblock (cfg, bb, branch1->inst_true_bb); + mono_unlink_bblock (cfg, bb, branch1->inst_false_bb); + branch1->inst_target_bb = next_bb; + mono_link_bblock (cfg, bb, next_bb); + + /* Rewrite the second branch */ + branch2->opcode = br_to_br_un (branch2->opcode); + + mono_merge_basic_blocks (cfg, bb, next_bb); + } + +#if 0 + for (bb = cfg->bb_entry; bb; bb = bb->next_bb) { + MonoBasicBlock *bb1, *bb2; + MonoInst *prev, *compare, *branch, *ins1, *ins2, *cmov, *move, *tmp; + gboolean simple, ret; + int dreg, tmp_reg; + CompType comp_type; + + /* Look for the IR code generated from if (cond) <- + * after branch opts which is: + * BB: + * compare + * b [BB1] + * <- + * BB1: + */ + if (!(bb->out_count == 1 && bb->extended && bb->code && bb->code->next && bb->code->next->next)) + continue; + + mono_print_bb (bb, ""); + + /* Find the compare instruction */ + prev = NULL; + compare = bb->code; + g_assert (compare); + while (compare->next->next && compare->next->next != bb->last_ins) { + prev = compare; + compare = compare->next; + } + branch = compare->next; + if (!MONO_IS_COND_BRANCH_OP (branch)) + continue; + } +#endif + + if (changed) { + if (cfg->opt & MONO_OPT_BRANCH) + mono_optimize_branches (cfg); + /* Merging bblocks could make some variables local */ + mono_handle_global_vregs (cfg); + if (cfg->opt & (MONO_OPT_CONSPROP | MONO_OPT_COPYPROP)) + mono_local_cprop (cfg); + if (cfg->opt & MONO_OPT_DEADCE) + mono_local_deadce (cfg); + } +#endif +} + +void +mono_nullify_basic_block (MonoBasicBlock *bb) +{ + bb->in_count = 0; + bb->out_count = 0; + bb->in_bb = NULL; + bb->out_bb = NULL; + bb->next_bb = NULL; + bb->code = bb->last_ins = NULL; + bb->cil_code = NULL; +} + +static void +replace_out_block (MonoBasicBlock *bb, MonoBasicBlock *orig, MonoBasicBlock *repl) +{ + int i; + + for (i = 0; i < bb->out_count; i++) { + MonoBasicBlock *ob = bb->out_bb [i]; + if (ob == orig) { + if (!repl) { + if (bb->out_count > 1) { + bb->out_bb [i] = bb->out_bb [bb->out_count - 1]; + } + bb->out_count--; + } else { + bb->out_bb [i] = repl; + } + } + } +} + +static void +replace_in_block (MonoBasicBlock *bb, MonoBasicBlock *orig, MonoBasicBlock *repl) +{ + int i; + + for (i = 0; i < bb->in_count; i++) { + MonoBasicBlock *ib = bb->in_bb [i]; + if (ib == orig) { + if (!repl) { + if (bb->in_count > 1) { + bb->in_bb [i] = bb->in_bb [bb->in_count - 1]; + } + bb->in_count--; + } else { + bb->in_bb [i] = repl; + } + } + } +} + +static void +replace_out_block_in_code (MonoBasicBlock *bb, MonoBasicBlock *orig, MonoBasicBlock *repl) { + MonoInst *ins; + +#if defined(__native_client_codegen__) + /* Need to maintain this flag for the new block because */ + /* we can't jump indirectly to a non-aligned block. */ + if (orig->flags & BB_INDIRECT_JUMP_TARGET) + { + repl->flags |= BB_INDIRECT_JUMP_TARGET; + } +#endif + + for (ins = bb->code; ins != NULL; ins = ins->next) { + switch (ins->opcode) { + case OP_BR: + if (ins->inst_target_bb == orig) + ins->inst_target_bb = repl; + break; + case OP_CALL_HANDLER: + if (ins->inst_target_bb == orig) + ins->inst_target_bb = repl; + break; + case OP_SWITCH: { + int i; + int n = GPOINTER_TO_INT (ins->klass); + for (i = 0; i < n; i++ ) { + if (ins->inst_many_bb [i] == orig) + ins->inst_many_bb [i] = repl; + } + break; + } + default: + if (MONO_IS_COND_BRANCH_OP (ins)) { + if (ins->inst_true_bb == orig) + ins->inst_true_bb = repl; + if (ins->inst_false_bb == orig) + ins->inst_false_bb = repl; + } else if (MONO_IS_JUMP_TABLE (ins)) { + int i; + MonoJumpInfoBBTable *table = MONO_JUMP_TABLE_FROM_INS (ins); + for (i = 0; i < table->table_size; i++ ) { + if (table->table [i] == orig) + table->table [i] = repl; + } + } + + break; + } + } +} + +/** + * Check if a bb is useless (is just made of NOPs and ends with an + * unconditional branch, or nothing). + * If it is so, unlink it from the CFG and nullify it, and return TRUE. + * Otherwise, return FALSE; + */ +static gboolean +remove_block_if_useless (MonoCompile *cfg, MonoBasicBlock *bb, MonoBasicBlock *previous_bb) { + MonoBasicBlock *target_bb = NULL; + MonoInst *inst; + + /* Do not touch handlers */ + if (bb->region != -1) { + bb->not_useless = TRUE; + return FALSE; + } + + MONO_BB_FOR_EACH_INS (bb, inst) { + switch (inst->opcode) { + case OP_NOP: + break; + case OP_BR: + target_bb = inst->inst_target_bb; + break; + default: + bb->not_useless = TRUE; + return FALSE; + } + } + + if (target_bb == NULL) { + if ((bb->out_count == 1) && (bb->out_bb [0] == bb->next_bb)) { + target_bb = bb->next_bb; + } else { + /* Do not touch empty BBs that do not "fall through" to their next BB (like the exit BB) */ + return FALSE; + } + } + + /* Do not touch BBs following a switch (they are the "default" branch) */ + if ((previous_bb->last_ins != NULL) && (previous_bb->last_ins->opcode == OP_SWITCH)) { + return FALSE; + } + + /* Do not touch BBs following the entry BB and jumping to something that is not */ + /* thiry "next" bb (the entry BB cannot contain the branch) */ + if ((previous_bb == cfg->bb_entry) && (bb->next_bb != target_bb)) { + return FALSE; + } + + /* + * Do not touch BBs following a try block as the code in + * mini_method_compile needs them to compute the length of the try block. + */ + if (MONO_BBLOCK_IS_IN_REGION (previous_bb, MONO_REGION_TRY)) + return FALSE; + + /* Check that there is a target BB, and that bb is not an empty loop (Bug 75061) */ + if ((target_bb != NULL) && (target_bb != bb)) { + int i; + + if (cfg->verbose_level > 1) { + printf ("remove_block_if_useless, removed BB%d\n", bb->block_num); + } + + /* unlink_bblock () modifies the bb->in_bb array so can't use a for loop here */ + while (bb->in_count) { + MonoBasicBlock *in_bb = bb->in_bb [0]; + mono_unlink_bblock (cfg, in_bb, bb); + mono_link_bblock (cfg, in_bb, target_bb); + replace_out_block_in_code (in_bb, bb, target_bb); + } + + mono_unlink_bblock (cfg, bb, target_bb); + if (previous_bb != cfg->bb_entry && mono_bb_is_fall_through (cfg, previous_bb)) { + for (i = 0; i < previous_bb->out_count; i++) { + if (previous_bb->out_bb [i] == target_bb) { + MonoInst *jump; + MONO_INST_NEW (cfg, jump, OP_BR); + MONO_ADD_INS (previous_bb, jump); + jump->cil_code = previous_bb->cil_code; + jump->inst_target_bb = target_bb; + break; + } + } + } + + previous_bb->next_bb = bb->next_bb; + mono_nullify_basic_block (bb); + + return TRUE; + } else { + return FALSE; + } +} + +void +mono_merge_basic_blocks (MonoCompile *cfg, MonoBasicBlock *bb, MonoBasicBlock *bbn) +{ + MonoInst *inst; + MonoBasicBlock *prev_bb; + int i; + + bb->has_array_access |= bbn->has_array_access; + bb->extended |= bbn->extended; + + mono_unlink_bblock (cfg, bb, bbn); + for (i = 0; i < bbn->out_count; ++i) + mono_link_bblock (cfg, bb, bbn->out_bb [i]); + while (bbn->out_count) + mono_unlink_bblock (cfg, bbn, bbn->out_bb [0]); + + /* Handle the branch at the end of the bb */ + if (bb->has_call_handler) { + for (inst = bb->code; inst != NULL; inst = inst->next) { + if (inst->opcode == OP_CALL_HANDLER) { + g_assert (inst->inst_target_bb == bbn); + NULLIFY_INS (inst); + } + } + } + if (bb->has_jump_table) { + for (inst = bb->code; inst != NULL; inst = inst->next) { + if (MONO_IS_JUMP_TABLE (inst)) { + int i; + MonoJumpInfoBBTable *table = MONO_JUMP_TABLE_FROM_INS (inst); + for (i = 0; i < table->table_size; i++ ) { + /* Might be already NULL from a previous merge */ + if (table->table [i]) + g_assert (table->table [i] == bbn); + table->table [i] = NULL; + } + /* Can't nullify this as later instructions depend on it */ + } + } + } + if (bb->last_ins && MONO_IS_COND_BRANCH_OP (bb->last_ins)) { + g_assert (bb->last_ins->inst_false_bb == bbn); + bb->last_ins->inst_false_bb = NULL; + bb->extended = TRUE; + } else if (bb->last_ins && MONO_IS_BRANCH_OP (bb->last_ins)) { + NULLIFY_INS (bb->last_ins); + } + + bb->has_call_handler |= bbn->has_call_handler; + bb->has_jump_table |= bbn->has_jump_table; + + if (bb->last_ins) { + if (bbn->code) { + bb->last_ins->next = bbn->code; + bbn->code->prev = bb->last_ins; + bb->last_ins = bbn->last_ins; + } + } else { + bb->code = bbn->code; + bb->last_ins = bbn->last_ins; + } + + for (prev_bb = cfg->bb_entry; prev_bb && prev_bb->next_bb != bbn; prev_bb = prev_bb->next_bb) + ; + if (prev_bb) { + prev_bb->next_bb = bbn->next_bb; + } else { + /* bbn might not be in the bb list yet */ + if (bb->next_bb == bbn) + bb->next_bb = bbn->next_bb; + } + mono_nullify_basic_block (bbn); + + /* + * If bbn fell through to its next bblock, have to add a branch, since bb + * will not fall though to the same bblock (#513931). + */ + if (bb->last_ins && bb->out_count == 1 && bb->out_bb [0] != bb->next_bb && !MONO_IS_BRANCH_OP (bb->last_ins)) { + MONO_INST_NEW (cfg, inst, OP_BR); + inst->inst_target_bb = bb->out_bb [0]; + MONO_ADD_INS (bb, inst); + } +} + +static void +move_basic_block_to_end (MonoCompile *cfg, MonoBasicBlock *bb) +{ + MonoBasicBlock *bbn, *next; + + next = bb->next_bb; + + /* Find the previous */ + for (bbn = cfg->bb_entry; bbn->next_bb && bbn->next_bb != bb; bbn = bbn->next_bb) + ; + if (bbn->next_bb) { + bbn->next_bb = bb->next_bb; + } + + /* Find the last */ + for (bbn = cfg->bb_entry; bbn->next_bb; bbn = bbn->next_bb) + ; + bbn->next_bb = bb; + bb->next_bb = NULL; + + /* Add a branch */ + if (next && (!bb->last_ins || ((bb->last_ins->opcode != OP_NOT_REACHED) && (bb->last_ins->opcode != OP_BR) && (bb->last_ins->opcode != OP_BR_REG) && (!MONO_IS_COND_BRANCH_OP (bb->last_ins))))) { + MonoInst *ins; + + MONO_INST_NEW (cfg, ins, OP_BR); + MONO_ADD_INS (bb, ins); + mono_link_bblock (cfg, bb, next); + ins->inst_target_bb = next; + } +} + +/* + * mono_remove_block: + * + * Remove BB from the control flow graph + */ +void +mono_remove_bblock (MonoCompile *cfg, MonoBasicBlock *bb) +{ + MonoBasicBlock *tmp_bb; + + for (tmp_bb = cfg->bb_entry; tmp_bb && tmp_bb->next_bb != bb; tmp_bb = tmp_bb->next_bb) + ; + + g_assert (tmp_bb); + tmp_bb->next_bb = bb->next_bb; +} + +void +mono_remove_critical_edges (MonoCompile *cfg) +{ + MonoBasicBlock *bb; + MonoBasicBlock *previous_bb; + + if (cfg->verbose_level > 3) { + for (bb = cfg->bb_entry; bb; bb = bb->next_bb) { + int i; + printf ("remove_critical_edges, BEFORE BB%d (in:", bb->block_num); + for (i = 0; i < bb->in_count; i++) { + printf (" %d", bb->in_bb [i]->block_num); + } + printf (") (out:"); + for (i = 0; i < bb->out_count; i++) { + printf (" %d", bb->out_bb [i]->block_num); + } + printf (")"); + if (bb->last_ins != NULL) { + printf (" "); + mono_print_ins (bb->last_ins); + } + printf ("\n"); + } + } + + for (previous_bb = cfg->bb_entry, bb = previous_bb->next_bb; bb != NULL; previous_bb = previous_bb->next_bb, bb = bb->next_bb) { + if (bb->in_count > 1) { + int in_bb_index; + for (in_bb_index = 0; in_bb_index < bb->in_count; in_bb_index++) { + MonoBasicBlock *in_bb = bb->in_bb [in_bb_index]; + /* + * Have to remove non-critical edges whose source ends with a BR_REG + * ins too, since inserting a computation before the BR_REG could + * overwrite the sreg1 of the ins. + */ + if ((in_bb->out_count > 1) || (in_bb->out_count == 1 && in_bb->last_ins && in_bb->last_ins->opcode == OP_BR_REG)) { + MonoBasicBlock *new_bb = mono_mempool_alloc0 ((cfg)->mempool, sizeof (MonoBasicBlock)); + new_bb->block_num = cfg->num_bblocks++; +// new_bb->real_offset = bb->real_offset; + new_bb->region = bb->region; + + /* Do not alter the CFG while altering the BB list */ + if (mono_bb_is_fall_through (cfg, previous_bb)) { + if (previous_bb != cfg->bb_entry) { + int i; + /* Make sure previous_bb really falls through bb */ + for (i = 0; i < previous_bb->out_count; i++) { + if (previous_bb->out_bb [i] == bb) { + MonoInst *jump; + MONO_INST_NEW (cfg, jump, OP_BR); + MONO_ADD_INS (previous_bb, jump); + jump->cil_code = previous_bb->cil_code; + jump->inst_target_bb = bb; + break; + } + } + } else { + /* We cannot add any inst to the entry BB, so we must */ + /* put a new BB in the middle to hold the OP_BR */ + MonoInst *jump; + MonoBasicBlock *new_bb_after_entry = mono_mempool_alloc0 ((cfg)->mempool, sizeof (MonoBasicBlock)); + new_bb_after_entry->block_num = cfg->num_bblocks++; +// new_bb_after_entry->real_offset = bb->real_offset; + new_bb_after_entry->region = bb->region; + + MONO_INST_NEW (cfg, jump, OP_BR); + MONO_ADD_INS (new_bb_after_entry, jump); + jump->cil_code = bb->cil_code; + jump->inst_target_bb = bb; + + mono_unlink_bblock (cfg, previous_bb, bb); + mono_link_bblock (cfg, new_bb_after_entry, bb); + mono_link_bblock (cfg, previous_bb, new_bb_after_entry); + + previous_bb->next_bb = new_bb_after_entry; + previous_bb = new_bb_after_entry; + + if (cfg->verbose_level > 2) { + printf ("remove_critical_edges, added helper BB%d jumping to BB%d\n", new_bb_after_entry->block_num, bb->block_num); + } + } + } + + /* Insert new_bb in the BB list */ + previous_bb->next_bb = new_bb; + new_bb->next_bb = bb; + previous_bb = new_bb; + + /* Setup in_bb and out_bb */ + new_bb->in_bb = mono_mempool_alloc ((cfg)->mempool, sizeof (MonoBasicBlock*)); + new_bb->in_bb [0] = in_bb; + new_bb->in_count = 1; + new_bb->out_bb = mono_mempool_alloc ((cfg)->mempool, sizeof (MonoBasicBlock*)); + new_bb->out_bb [0] = bb; + new_bb->out_count = 1; + + /* Relink in_bb and bb to (from) new_bb */ + replace_out_block (in_bb, bb, new_bb); + replace_out_block_in_code (in_bb, bb, new_bb); + replace_in_block (bb, in_bb, new_bb); + + if (cfg->verbose_level > 2) { + printf ("remove_critical_edges, removed critical edge from BB%d to BB%d (added BB%d)\n", in_bb->block_num, bb->block_num, new_bb->block_num); + } + } + } + } + } + + if (cfg->verbose_level > 3) { + for (bb = cfg->bb_entry; bb; bb = bb->next_bb) { + int i; + printf ("remove_critical_edges, AFTER BB%d (in:", bb->block_num); + for (i = 0; i < bb->in_count; i++) { + printf (" %d", bb->in_bb [i]->block_num); + } + printf (") (out:"); + for (i = 0; i < bb->out_count; i++) { + printf (" %d", bb->out_bb [i]->block_num); + } + printf (")"); + if (bb->last_ins != NULL) { + printf (" "); + mono_print_ins (bb->last_ins); + } + printf ("\n"); + } + } +} + +/* + * Optimizes the branches on the Control Flow Graph + * + */ +void +mono_optimize_branches (MonoCompile *cfg) +{ + int i, changed = FALSE; + MonoBasicBlock *bb, *bbn; + guint32 niterations; + + /* + * Some crazy loops could cause the code below to go into an infinite + * loop, see bug #53003 for an example. To prevent this, we put an upper + * bound on the number of iterations. + */ + if (cfg->num_bblocks > 1000) + niterations = cfg->num_bblocks * 2; + else + niterations = 1000; + + do { + MonoBasicBlock *previous_bb; + changed = FALSE; + niterations --; + + /* we skip the entry block (exit is handled specially instead ) */ + for (previous_bb = cfg->bb_entry, bb = cfg->bb_entry->next_bb; bb; previous_bb = bb, bb = bb->next_bb) { + /* dont touch code inside exception clauses */ + if (bb->region != -1) + continue; + + if (!bb->not_useless && remove_block_if_useless (cfg, bb, previous_bb)) { + changed = TRUE; + continue; + } + + if ((bbn = bb->next_bb) && bbn->in_count == 0 && bbn != cfg->bb_exit && bb->region == bbn->region) { + if (cfg->verbose_level > 2) + g_print ("nullify block triggered %d\n", bbn->block_num); + + bb->next_bb = bbn->next_bb; + + for (i = 0; i < bbn->out_count; i++) + replace_in_block (bbn->out_bb [i], bbn, NULL); + + mono_nullify_basic_block (bbn); + changed = TRUE; + } + + if (bb->out_count == 1) { + bbn = bb->out_bb [0]; + + /* conditional branches where true and false targets are the same can be also replaced with OP_BR */ + if (bb->last_ins && (bb->last_ins->opcode != OP_BR) && MONO_IS_COND_BRANCH_OP (bb->last_ins)) { + bb->last_ins->opcode = OP_BR; + bb->last_ins->inst_target_bb = bb->last_ins->inst_true_bb; + changed = TRUE; + if (cfg->verbose_level > 2) + g_print ("cond branch removal triggered in %d %d\n", bb->block_num, bb->out_count); + } + + if (bb->region == bbn->region && bb->next_bb == bbn) { + /* the block are in sequence anyway ... */ + + /* branches to the following block can be removed */ + if (bb->last_ins && bb->last_ins->opcode == OP_BR && !bbn->out_of_line) { + bb->last_ins->opcode = OP_NOP; + changed = TRUE; + if (cfg->verbose_level > 2) + g_print ("br removal triggered %d -> %d\n", bb->block_num, bbn->block_num); + } + + if (bbn->in_count == 1 && !bb->extended) { + if (bbn != cfg->bb_exit) { + if (cfg->verbose_level > 2) + g_print ("block merge triggered %d -> %d\n", bb->block_num, bbn->block_num); + mono_merge_basic_blocks (cfg, bb, bbn); + changed = TRUE; + continue; + } + + //mono_print_bb_code (bb); + } + } + } + + if ((bbn = bb->next_bb) && bbn->in_count == 0 && bbn != cfg->bb_exit && bb->region == bbn->region) { + if (cfg->verbose_level > 2) { + g_print ("nullify block triggered %d\n", bbn->block_num); + } + bb->next_bb = bbn->next_bb; + + for (i = 0; i < bbn->out_count; i++) + replace_in_block (bbn->out_bb [i], bbn, NULL); + + mono_nullify_basic_block (bbn); + changed = TRUE; + continue; + } + + if (bb->out_count == 1) { + bbn = bb->out_bb [0]; + + if (bb->last_ins && bb->last_ins->opcode == OP_BR) { + bbn = bb->last_ins->inst_target_bb; + if (bb->region == bbn->region && bbn->code && bbn->code->opcode == OP_BR && + bbn->code->inst_target_bb != bbn && + bbn->code->inst_target_bb->region == bb->region) { + + if (cfg->verbose_level > 2) + g_print ("branch to branch triggered %d -> %d -> %d\n", bb->block_num, bbn->block_num, bbn->code->inst_target_bb->block_num); + + replace_in_block (bbn, bb, NULL); + replace_out_block (bb, bbn, bbn->code->inst_target_bb); + mono_link_bblock (cfg, bb, bbn->code->inst_target_bb); + bb->last_ins->inst_target_bb = bbn->code->inst_target_bb; + changed = TRUE; + continue; + } + } + } else if (bb->out_count == 2) { + if (bb->last_ins && MONO_IS_COND_BRANCH_NOFP (bb->last_ins)) { + int branch_result; + MonoBasicBlock *taken_branch_target = NULL, *untaken_branch_target = NULL; + + if (bb->last_ins->flags & MONO_INST_CFOLD_TAKEN) + branch_result = BRANCH_TAKEN; + else if (bb->last_ins->flags & MONO_INST_CFOLD_NOT_TAKEN) + branch_result = BRANCH_NOT_TAKEN; + else + branch_result = BRANCH_UNDEF; + + if (branch_result == BRANCH_TAKEN) { + taken_branch_target = bb->last_ins->inst_true_bb; + untaken_branch_target = bb->last_ins->inst_false_bb; + } else if (branch_result == BRANCH_NOT_TAKEN) { + taken_branch_target = bb->last_ins->inst_false_bb; + untaken_branch_target = bb->last_ins->inst_true_bb; + } + if (taken_branch_target) { + /* if mono_eval_cond_branch () is ever taken to handle + * non-constant values to compare, issue a pop here. + */ + bb->last_ins->opcode = OP_BR; + bb->last_ins->inst_target_bb = taken_branch_target; + if (!bb->extended) + mono_unlink_bblock (cfg, bb, untaken_branch_target); + changed = TRUE; + continue; + } + bbn = bb->last_ins->inst_true_bb; + if (bb->region == bbn->region && bbn->code && bbn->code->opcode == OP_BR && + bbn->code->inst_target_bb->region == bb->region) { + if (cfg->verbose_level > 2) + g_print ("cbranch1 to branch triggered %d -> (%d) %d (0x%02x)\n", + bb->block_num, bbn->block_num, bbn->code->inst_target_bb->block_num, + bbn->code->opcode); + + /* + * Unlink, then relink bblocks to avoid various + * tricky situations when the two targets of the branch + * are equal, or will become equal after the change. + */ + mono_unlink_bblock (cfg, bb, bb->last_ins->inst_true_bb); + mono_unlink_bblock (cfg, bb, bb->last_ins->inst_false_bb); + + bb->last_ins->inst_true_bb = bbn->code->inst_target_bb; + + mono_link_bblock (cfg, bb, bb->last_ins->inst_true_bb); + mono_link_bblock (cfg, bb, bb->last_ins->inst_false_bb); + + changed = TRUE; + continue; + } + + bbn = bb->last_ins->inst_false_bb; + if (bbn && bb->region == bbn->region && bbn->code && bbn->code->opcode == OP_BR && + bbn->code->inst_target_bb->region == bb->region) { + if (cfg->verbose_level > 2) + g_print ("cbranch2 to branch triggered %d -> (%d) %d (0x%02x)\n", + bb->block_num, bbn->block_num, bbn->code->inst_target_bb->block_num, + bbn->code->opcode); + + mono_unlink_bblock (cfg, bb, bb->last_ins->inst_true_bb); + mono_unlink_bblock (cfg, bb, bb->last_ins->inst_false_bb); + + bb->last_ins->inst_false_bb = bbn->code->inst_target_bb; + + mono_link_bblock (cfg, bb, bb->last_ins->inst_true_bb); + mono_link_bblock (cfg, bb, bb->last_ins->inst_false_bb); + + changed = TRUE; + continue; + } + + bbn = bb->last_ins->inst_false_bb; + /* + * If bb is an extended bb, it could contain an inside branch to bbn. + * FIXME: Enable the optimization if that is not true. + * If bblocks_linked () is true, then merging bb and bbn + * would require addition of an extra branch at the end of bbn + * slowing down loops. + */ + if (bbn && bb->region == bbn->region && bbn->in_count == 1 && cfg->enable_extended_bblocks && bbn != cfg->bb_exit && !bb->extended && !bbn->out_of_line && !mono_bblocks_linked (bbn, bb)) { + g_assert (bbn->in_bb [0] == bb); + if (cfg->verbose_level > 2) + g_print ("merge false branch target triggered BB%d -> BB%d\n", bb->block_num, bbn->block_num); + mono_merge_basic_blocks (cfg, bb, bbn); + changed = TRUE; + continue; + } + } + + if (bb->last_ins && MONO_IS_COND_BRANCH_NOFP (bb->last_ins)) { + if (bb->last_ins->inst_false_bb && bb->last_ins->inst_false_bb->out_of_line && (bb->region == bb->last_ins->inst_false_bb->region) && !cfg->disable_out_of_line_bblocks) { + /* Reverse the branch */ + bb->last_ins->opcode = mono_reverse_branch_op (bb->last_ins->opcode); + bbn = bb->last_ins->inst_false_bb; + bb->last_ins->inst_false_bb = bb->last_ins->inst_true_bb; + bb->last_ins->inst_true_bb = bbn; + + move_basic_block_to_end (cfg, bb->last_ins->inst_true_bb); + if (cfg->verbose_level > 2) + g_print ("cbranch to throw block triggered %d.\n", + bb->block_num); + } + } + } + } + } while (changed && (niterations > 0)); +} + +#endif /* DISABLE_JIT */