X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fopt%2Fjumpthreading.c;h=eeca132b4b7d32bde3c0dbcdf591c93403fbe226;hb=a55eb59057eb8c7eb94cdb173dc254098c0c09cc;hp=fb0d5c1cd5854be381bd53b026b98218719a9bd2;hpb=2dcaef3632eb1e6f1e8e98ebf2419832ec72a338;p=libfirm diff --git a/ir/opt/jumpthreading.c b/ir/opt/jumpthreading.c index fb0d5c1cd..eeca132b4 100644 --- a/ir/opt/jumpthreading.c +++ b/ir/opt/jumpthreading.c @@ -22,13 +22,13 @@ * @brief Path-Sensitive Jump Threading * @date 10. Sep. 2006 * @author Christoph Mallon, Matthias Braun - * @version $Id$ */ #include "config.h" #include "iroptimize.h" #include +#include #include "array_t.h" #include "debug.h" #include "ircons.h" @@ -49,7 +49,7 @@ #undef AVOID_PHIB -DEBUG_ONLY(static firm_dbg_module_t *dbg); +DEBUG_ONLY(static firm_dbg_module_t *dbg;) /** * Add the new predecessor x to node node, which is either a Block or a Phi @@ -60,7 +60,7 @@ static void add_pred(ir_node* node, ir_node* x) int n; int i; - assert(is_Block(node) || is_Phi(node)); + assert(is_Block(node)); n = get_irn_arity(node); NEW_ARR_A(ir_node*, ins, n + 1); @@ -83,10 +83,10 @@ static ir_node *search_def_and_create_phis(ir_node *block, ir_mode *mode, ir_node **in; ir_node *dummy; - /* This is needed because we create bads sometimes */ - if (is_Block_dead(block)) { + /* In case of a bad input to a block we need to return the bad value */ + if (is_Bad(block)) { ir_graph *irg = get_irn_irg(block); - return new_r_Bad(irg); + return new_r_Bad(irg, mode); } /* the other defs can't be marked for cases where a user of the original @@ -194,6 +194,16 @@ static void construct_ssa(ir_node *orig_block, ir_node *orig_val, } } +/** + * jumpthreading produces critical edges, e.g. B-C: + * A A + * \ / \ | + * B => B | + * / \ / \| + * C C + * + * By splitting this critical edge more threadings might be possible. + */ static void split_critical_edge(ir_node *block, int pos) { ir_graph *irg = get_irn_irg(block); @@ -275,9 +285,16 @@ static void copy_and_fix(const jumpthreading_env_t *env, ir_node *block, ir_node *copy; ir_mode *mode; + if (is_End(node)) { + /* edge is a Keep edge. If the end block is unreachable via normal control flow, + * we must maintain end's reachability with Keeps. + */ + keep_alive(copy_block); + continue; + } /* ignore control flow */ mode = get_irn_mode(node); - if (mode == mode_X || is_Cond(node)) + if (mode == mode_X || is_Cond(node) || is_Switch(node)) continue; #ifdef AVOID_PHIB /* we may not copy mode_b nodes, because this could produce Phi with @@ -330,7 +347,7 @@ static void copy_and_fix(const jumpthreading_env_t *env, ir_node *block, ir_mode *mode; mode = get_irn_mode(node); - if (mode == mode_X || is_Cond(node)) + if (mode == mode_X || is_Cond(node) || is_Switch(node)) continue; #ifdef AVOID_PHIB if (mode == mode_b) @@ -616,7 +633,7 @@ static ir_node *find_candidate(jumpthreading_env_t *env, ir_node *jump, static void thread_jumps(ir_node* block, void* data) { jumpthreading_env_t env; - int *changed = (int*)data; + bool *changed = (bool*)data; ir_node *selector; ir_node *projx; ir_node *cond; @@ -624,9 +641,10 @@ static void thread_jumps(ir_node* block, void* data) int selector_evaluated; const ir_edge_t *edge, *next; ir_graph *irg; - ir_node *bad; + ir_node *badX; int cnst_pos; + /* we do not deal with Phis, so restrict this to exactly one cfgpred */ if (get_Block_n_cfgpreds(block) != 1) return; @@ -636,15 +654,12 @@ static void thread_jumps(ir_node* block, void* data) assert(get_irn_mode(projx) == mode_X); cond = get_Proj_pred(projx); - if (!is_Cond(cond)) - return; - - selector = get_Cond_selector(cond); /* TODO handle switch Conds */ - if (get_irn_mode(selector) != mode_b) + if (!is_Cond(cond)) return; /* handle cases that can be immediately evaluated */ + selector = get_Cond_selector(cond); selector_evaluated = -1; if (is_Cmp(selector)) { ir_node *left = get_Cmp_left(selector); @@ -686,16 +701,16 @@ static void thread_jumps(ir_node* block, void* data) if (selector_evaluated == 0) { ir_graph *irg = get_irn_irg(block); - bad = new_r_Bad(irg); + ir_node *bad = new_r_Bad(irg, mode_X); exchange(projx, bad); - *changed = 1; + *changed = true; return; } else if (selector_evaluated == 1) { dbg_info *dbgi = get_irn_dbg_info(selector); ir_node *jmp = new_rd_Jmp(dbgi, get_nodes_block(projx)); DBG_OPT_JUMPTHREADING(projx, jmp); exchange(projx, jmp); - *changed = 1; + *changed = true; return; } @@ -709,64 +724,59 @@ static void thread_jumps(ir_node* block, void* data) if (copy_block == NULL) return; + /* We might thread the condition block of an infinite loop, + * such that there is no path to End anymore. */ + keep_alive(block); + /* we have to remove the edge towards the pred as the pred now * jumps into the true_block. We also have to shorten Phis * in our block because of this */ - bad = new_r_Bad(irg); + badX = new_r_Bad(irg, mode_X); cnst_pos = env.cnst_pos; /* shorten Phis */ foreach_out_edge_safe(env.cnst_pred, edge, next) { ir_node *node = get_edge_src_irn(edge); - if (is_Phi(node)) + if (is_Phi(node)) { + ir_node *bad = new_r_Bad(irg, get_irn_mode(node)); set_Phi_pred(node, cnst_pos, bad); + } } - set_Block_cfgpred(env.cnst_pred, cnst_pos, bad); + set_Block_cfgpred(env.cnst_pred, cnst_pos, badX); /* the graph is changed now */ - *changed = 1; + *changed = true; } void opt_jumpthreading(ir_graph* irg) { - int changed, rerun; + bool changed; + bool rerun; + + assure_irg_properties(irg, + IR_GRAPH_PROPERTY_NO_UNREACHABLE_CODE + | IR_GRAPH_PROPERTY_CONSISTENT_OUT_EDGES + | IR_GRAPH_PROPERTY_NO_CRITICAL_EDGES); FIRM_DBG_REGISTER(dbg, "firm.opt.jumpthreading"); DB((dbg, LEVEL_1, "===> Performing jumpthreading on %+F\n", irg)); - remove_critical_cf_edges(irg); - - /* ugly: jump threading might get confused by garbage nodes - * of mode_X in copy_and_fix_node(), so remove all garbage edges. */ - edges_deactivate(irg); - - edges_assure(irg); ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK | IR_RESOURCE_IRN_VISITED); - changed = 0; + changed = false; do { - rerun = 0; + rerun = false; irg_block_walk_graph(irg, thread_jumps, NULL, &rerun); changed |= rerun; } while (rerun); ir_free_resources(irg, IR_RESOURCE_IRN_LINK | IR_RESOURCE_IRN_VISITED); - if (changed) { - /* control flow changed, some blocks may become dead */ - set_irg_outs_inconsistent(irg); - set_irg_doms_inconsistent(irg); - set_irg_extblk_inconsistent(irg); - set_irg_loopinfo_inconsistent(irg); - set_irg_entity_usage_state(irg, ir_entity_usage_not_computed); - - /* Dead code might be created. Optimize it away as it is dangerous - * to call optimize_df() an dead code. */ - optimize_cf(irg); - } + confirm_irg_properties(irg, + changed ? IR_GRAPH_PROPERTIES_NONE : IR_GRAPH_PROPERTIES_ALL); } /* Creates an ir_graph pass for opt_jumpthreading. */