From: unknown Date: Mon, 30 May 2011 17:00:18 +0000 (+0200) Subject: Some cleanup of cfopt. X-Git-Url: http://nsz.repo.hu/git/?a=commitdiff_plain;h=2b7851654f662026548655434f80c7fce7f5de5a;p=libfirm Some cleanup of cfopt. - renamed clear_link() to clear_link_and_mark_blocks_removable() - renamed optimize_conds() to optimize_ifs() - simplified has_*() implementations - made some walker POST walker - invalidate out edges - and add some doxygen docu - fixed some typos - adapt to firm indentation style --- diff --git a/ir/opt/cfopt.c b/ir/opt/cfopt.c index 7cc98a794..d833f8fe8 100644 --- a/ir/opt/cfopt.c +++ b/ir/opt/cfopt.c @@ -66,22 +66,26 @@ typedef struct merge_env { bool phis_moved; /**< Set if Phi nodes were moved. */ } merge_env; +/** set or reset the removable property of a block. */ static void set_Block_removable(ir_node *block, bool removable) { set_Block_mark(block, removable); } +/** check if a block has the removable property set. */ static bool is_Block_removable(ir_node *block) { return get_Block_mark(block); } +/** checks if a given Cond node is a switch Cond. */ static bool is_switch_Cond(ir_node *cond) { ir_node *sel = get_Cond_selector(cond); return get_irn_mode(sel) != mode_b; } -static void clear_link(ir_node *node, void *ctx) +/** Walker: clear link fields and mark all blocks as removable. */ +static void clear_link_and_mark_blocks_removable(ir_node *node, void *ctx) { (void) ctx; set_irn_link(node, NULL); @@ -106,8 +110,10 @@ static void collect_nodes(ir_node *n, void *ctx) set_irn_link(n, get_irn_link(block)); set_irn_link(block, n); } else if (is_Block(n)) { - if (has_Block_entity(n)) + if (has_Block_entity(n)) { + /* block with a jump label attached cannot be removed. */ set_Block_removable(n, false); + } return; } else if (!is_Jmp(n)) { /* Check for non-empty block. */ ir_node *block = get_nodes_block(n); @@ -125,7 +131,7 @@ static void collect_nodes(ir_node *n, void *ctx) } } -/** Returns true if pred is predecessor of block. */ +/** Returns true if pred is predecessor of block b. */ static bool is_pred_of(ir_node *pred, ir_node *b) { int i; @@ -502,7 +508,7 @@ static bool handle_switch_cond(ir_node *cond) /* handle Cond nodes with constant argument. In this case the localopt rules * should have killed all obviously impossible cases. - * So the only case left to handle here is 1 defaultProj + 1case + * So the only case left to handle here is 1 defaultProj + 1 case * (this one case should be the one taken) */ if (get_irn_link(proj2) == NULL) { ir_tarval *tv = value_of(sel); @@ -549,38 +555,9 @@ static bool handle_switch_cond(ir_node *cond) return false; } -static bool get_phase_flag(ir_phase *block_info, ir_node *block, int offset) { - return ((int)phase_get_irn_data(block_info, block)) & (1<phase,b)) return; + if (has_phis(env->phase, block)) + return; /* optimize Cond predecessors (might produce Bad predecessors) */ - for (i = 0; i < n_preds; i++) { - for (j = i+1; j < n_preds; j++) { - optimize_pred_cond(b, i, j); + for (i = 0; i < n_preds; ++i) { + for (j = i+1; j < n_preds; ++j) { + optimize_pred_cond(block, i, j); } } } -static void remove_empty_blocks(ir_node *b, void *x) +/** + * Post-Block walker: remove empty blocks that are + * predecessors of the current block. + */ +static void remove_empty_blocks(ir_node *block, void *x) { skip_env *env = (skip_env*)x; int i; - int n_preds = get_Block_n_cfgpreds(b); + int n_preds = get_Block_n_cfgpreds(block); for (i = 0; i < n_preds; ++i) { ir_node *jmp, *jmp_block, *pred, *pred_block; - jmp = get_Block_cfgpred(b, i); - if (!is_Jmp(jmp)) continue; - if (is_unknown_jump(jmp)) continue; + jmp = get_Block_cfgpred(block, i); + if (!is_Jmp(jmp)) + continue; jmp_block = get_nodes_block(jmp); - if (is_unknown_jump_target(env->phase, jmp_block)) continue; - if (has_operations(env->phase,jmp_block)) continue; + if (is_unknown_jump_target(env->phase, jmp_block)) + continue; + if (has_operations(env->phase,jmp_block)) + continue; /* jmp_block is an empty block! */ - if (get_Block_n_cfgpreds(jmp_block) != 1) continue; + if (get_Block_n_cfgpreds(jmp_block) != 1) + continue; pred = get_Block_cfgpred(jmp_block, 0); exchange(jmp, pred); env->changed = true; @@ -687,21 +716,22 @@ static void remove_empty_blocks(ir_node *b, void *x) } /* - * Some cfg optimizations, which do not touch Phi nodes */ + * Some cfg optimizations, which do not touch Phi nodes + */ static void cfgopt_ignoring_phis(ir_graph *irg) { ir_phase *block_info = new_phase(irg, NULL); skip_env env = { false, block_info }; irg_walk_graph(irg, compute_block_info, NULL, block_info); - for(;;) { + for (;;) { env.changed = false; - /* Conds => Jmp optimization; might produce empty blocks */ - irg_block_walk_graph(irg, optimize_conds, NULL, &env); + /* useless if optimization: will not touch empty blocks */ + irg_block_walk_graph(irg, NULL, optimize_ifs, &env); /* Remove empty blocks */ - irg_block_walk_graph(irg, remove_empty_blocks, NULL, &env); + irg_block_walk_graph(irg, NULL, remove_empty_blocks, &env); if (env.changed) { set_irg_doms_inconsistent(irg); /* Removing blocks might enable more Cond optimizations */ @@ -723,6 +753,9 @@ void optimize_cf(ir_graph *irg) ir_node *new_end; merge_env env; + env.changed = false; + env.phis_moved = false; + assert(get_irg_phase_state(irg) != phase_building); /* if the graph is not pinned, we cannot determine empty blocks */ @@ -742,8 +775,7 @@ void optimize_cf(ir_graph *irg) for (;;) { int length; ir_node **switch_conds = NULL; - env.changed = false; - env.phis_moved = false; + bool changed = false; assure_doms(irg); @@ -754,18 +786,20 @@ void optimize_cf(ir_graph *irg) * computations, i.e., these blocks might be removed. */ switch_conds = NEW_ARR_F(ir_node*, 0); - irg_walk(end, clear_link, collect_nodes, &switch_conds); + irg_walk(end, clear_link_and_mark_blocks_removable, collect_nodes, &switch_conds); /* handle all collected switch-Conds */ length = ARR_LEN(switch_conds); for (i = 0; i < length; ++i) { ir_node *cond = switch_conds[i]; - env.changed |= handle_switch_cond(cond); + changed |= handle_switch_cond(cond); } DEL_ARR_F(switch_conds); - if (!env.changed) break; + if (!changed) + break; + set_irg_outs_inconsistent(irg); set_irg_doms_inconsistent(irg); set_irg_extblk_inconsistent(irg); set_irg_entity_usage_state(irg, ir_entity_usage_not_computed); @@ -795,7 +829,7 @@ void optimize_cf(ir_graph *irg) if (env.phis_moved) { /* Bad: when we moved Phi's, we might produce dead Phi nodes that are kept-alive. - Some other phases cannot copy with this, so will them. + Some other phases cannot copy with this, so kill them. */ n = get_End_n_keepalives(end); if (n > 0) { @@ -830,6 +864,7 @@ void optimize_cf(ir_graph *irg) if (env.changed) { /* Handle graph state if was changed. */ + set_irg_outs_inconsistent(irg); set_irg_doms_inconsistent(irg); set_irg_extblk_inconsistent(irg); set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);