X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fopt%2Fcfopt.c;h=be03bfad64181658cfd6db7625f869410fb28301;hb=c7dc950ac0cdd7d24acffb798b5867d0db5dd7c8;hp=19798e85d858ed7da51fa5922d16041c54e18e7e;hpb=73612d7017e1ca49ba736e4e6e3c0a73813e53b4;p=libfirm diff --git a/ir/opt/cfopt.c b/ir/opt/cfopt.c index 19798e85d..be03bfad6 100644 --- a/ir/opt/cfopt.c +++ b/ir/opt/cfopt.c @@ -1,18 +1,34 @@ /* - * Project: libFIRM - * File name: ir/opt/cfopt.c - * Purpose: control flow optimizations - * Author: - * Created: - * CVS-ID: $Id$ - * Copyright: (c) 1998-2004 Universität Karlsruhe - * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE. + * Copyright (C) 1995-2008 University of Karlsruhe. All right reserved. + * + * This file is part of libFirm. + * + * This file may be distributed and/or modified under the terms of the + * GNU General Public License version 2 as published by the Free Software + * Foundation and appearing in the file LICENSE.GPL included in the + * packaging of this file. + * + * Licensees holding valid libFirm Professional Edition licenses may use + * this file in accordance with the libFirm Commercial License. + * Agreement provided with the Software. + * + * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE + * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE. */ +/** + * @file + * @brief Control flow optimizations. + * @author Goetz Lindenmaier, Michael Beck, Sebastian Hack + * @version $Id$ + */ #ifdef HAVE_CONFIG_H # include "config.h" #endif +#include "iroptimize.h" + #include #include "plist.h" @@ -37,7 +53,6 @@ #include "irflag_t.h" #include "firmstat.h" -#include "cfopt.h" #include "iropt_dbg.h" /*------------------------------------------------------------------*/ @@ -47,10 +62,12 @@ /* is empty if it contains only a Jmp node. */ /* Blocks can only be removed if they are not needed for the */ /* semantics of Phi nodes. */ +/* Further, we NEVER remove labeled blocks (even if we could move */ +/* the label. */ /*------------------------------------------------------------------*/ /** - * Replace binary Conds that jumps twice into the same block + * Block walker, replacing binary Conds that jumps twice into the same block * by a simple Jmp. * E.g. * @verbatim @@ -66,9 +83,10 @@ * Note that the simple case that Block has only these two * predecessors are already handled in equivalent_node_Block(). */ -static void remove_senseless_conds(ir_node *bl, void *data) { +static void remove_senseless_conds(ir_node *bl, void *env) { int i, j; int n = get_Block_n_cfgpreds(bl); + int *changed = env; assert(is_Block(bl)); @@ -89,6 +107,7 @@ static void remove_senseless_conds(ir_node *bl, void *data) { set_irn_n(bl, j, new_Bad()); DBG_OPT_IFSIM2(cond_i, jmp); + *changed = 1; break; } } @@ -96,6 +115,13 @@ static void remove_senseless_conds(ir_node *bl, void *data) { } } +/** An environment for merge_blocks and collect nodes. */ +typedef struct _merge_env { + int changed; /**< Set if the graph was changed. */ + int phis_moved; /**< Set if Phi nodes were moved. */ + plist_t *list; /**< Helper list for all found Switch Conds. */ +} merge_env; + /** * Removes Tuples from Block control flow predecessors. * Optimizes blocks with equivalent_node(). This is tricky, @@ -103,27 +129,31 @@ static void remove_senseless_conds(ir_node *bl, void *data) { * Therefore we also optimize at control flow operations, depending * how we first reach the Block. */ -static void merge_blocks(ir_node *node, void *env) { - int i, n; +static void merge_blocks(ir_node *node, void *ctx) { + int i; ir_node *new_block; + merge_env *env = ctx; /* clear the link field for ALL nodes first */ set_irn_link(node, NULL); if (is_Block(node)) { /* Remove Tuples */ - - /* GL @@@ : is this possible? if (get_opt_normalize()) -- added, all tests go through. - A different order of optimizations might cause problems. */ - if (get_opt_normalize()) { - for (i = 0, n = get_Block_n_cfgpreds(node); i < n; ++i) - set_Block_cfgpred(node, i, skip_Tuple(get_Block_cfgpred(node, i))); + for (i = get_Block_n_cfgpreds(node) - 1; i >= 0; --i) { + ir_node *pred = get_Block_cfgpred(node, i); + ir_node *skipped = skip_Tuple(pred); + if (pred != skipped) { + set_Block_cfgpred(node, i, skipped); + env->changed = 1; + } } /* see below */ new_block = equivalent_node(node); - if (new_block != node && ! is_Block_dead(new_block)) + if (new_block != node && ! is_Block_dead(new_block)) { exchange(node, new_block); + env->changed = 1; + } } else if (get_opt_optimize() && (get_irn_mode(node) == mode_X)) { /* We will soon visit a block. Optimize it before visiting! */ @@ -140,7 +170,8 @@ static void merge_blocks(ir_node *node, void *env) { assert((get_opt_control_flow_straightening() || get_opt_control_flow_weak_simplification()) && ("strange flag setting")); - exchange (b, new_block); + exchange(b, new_block); + env->changed = 1; b = new_block; new_block = equivalent_node(b); } @@ -148,15 +179,17 @@ static void merge_blocks(ir_node *node, void *env) { /* normally, we would create a Bad block here, but this must be * prevented, so just set it's cf to Bad. */ - if (is_Block_dead(new_block)) + if (is_Block_dead(new_block)) { exchange(node, new_Bad()); + env->changed = 1; + } } } } - /** - * Remove cf from dead block by inspecting dominance info + * Block walker removing control flow from dead block by + * inspecting dominance info. * Do not replace blocks by Bad. This optimization shall * ensure, that all Bad control flow predecessors are * removed, and no new other Bads are introduced. @@ -165,6 +198,7 @@ static void merge_blocks(ir_node *node, void *env) { */ static void remove_dead_block_cf(ir_node *block, void *env) { int i; + int *changed = env; /* check block predecessors and turn control flow into bad */ for (i = get_Block_n_cfgpreds(block) - 1; i >= 0; --i) { @@ -176,6 +210,7 @@ static void remove_dead_block_cf(ir_node *block, void *env) { if (is_Block_dead(pred_bl) || (get_Block_dom_depth(pred_bl) < 0)) { set_Block_dead(pred_bl); exchange(pred_X, new_Bad()); + *changed = 1; } } } @@ -188,14 +223,18 @@ static void remove_dead_block_cf(ir_node *block, void *env) { * Links all Proj nodes to their predecessors. * Collects all switch-Conds in a list. */ -static void collect_nodes(ir_node *n, void *env) { +static void collect_nodes(ir_node *n, void *ctx) { ir_op *op = get_irn_op(n); - plist_t *list = env; + merge_env *env = ctx; - if (op != op_Block) { + if (op == op_Block) { + /* mark the block as non-empty if it is labeled */ + if (has_Block_label(n)) + mark_Block_block_visited(n); + } else { ir_node *b = get_nodes_block(n); - if (op == op_Phi) { + if (op == op_Phi && get_irn_arity(n) > 0) { /* Collect Phi nodes to compact ins along with block's ins. */ set_irn_link(n, get_irn_link(b)); set_irn_link(b, n); @@ -211,7 +250,7 @@ static void collect_nodes(ir_node *n, void *env) { ir_node *sel = get_Cond_selector(n); if (mode_is_int(get_irn_mode(sel))) { /* found a switch-Cond, collect */ - plist_insert_back(list, n); + plist_insert_back(env->list, n); } } } @@ -274,7 +313,7 @@ static int test_whether_dispensable(ir_node *b, int pos) { } /* Seems to be empty. At least we detected this in collect_nodes. */ - if (!get_irn_link(b)) { + if (get_irn_link(b) == NULL) { /* There are no Phi nodes ==> all predecessors are dispensable. */ n_preds = get_Block_n_cfgpreds(pred); } else { @@ -312,14 +351,6 @@ non_dispensable: return 1; } -/** - * Store to defer the exchanged of Phi nodes. - */ -typedef struct _defer_ex_phi { - ir_node *phi_pred; /**< the previous Phi node that will be replaced */ - ir_node *phi; /**< the new Phi node that replaces phi_pred */ -} defer_ex_phi; - /** * This method removed Bad cf predecessors from Blocks and Phis, and removes * empty blocks. A block is empty if it only contains Phi and Jmp nodes. @@ -367,11 +398,11 @@ typedef struct _defer_ex_phi { * @@@ It is negotiable whether we should do this ... there might end up a copy * from the Phi in the loop when removing the Phis. */ -static void optimize_blocks(ir_node *b, void *env) { +static void optimize_blocks(ir_node *b, void *ctx) { int i, j, k, n, max_preds, n_preds, p_preds = -1; ir_node *pred, *phi; ir_node **in; - defer_ex_phi *defers; + merge_env *env = ctx; /* Count the number of predecessor if this block is merged with pred blocks that are empty. */ @@ -381,21 +412,6 @@ static void optimize_blocks(ir_node *b, void *env) { } in = xmalloc(max_preds * sizeof(*in)); - defers = NEW_ARR_F(defer_ex_phi, 0); - - /*- - printf(" working on "); DDMN(b); - for (i = 0; i < get_Block_n_cfgpreds(b); i++) { - pred = get_nodes_block(get_Block_cfgpred(b, i)); - if (is_Bad(get_Block_cfgpred(b, i))) { - printf(" removing Bad %i\n ", i); - } else if (get_Block_block_visited(pred) +1 - < get_irg_block_visited(current_ir_graph)) { - printf(" removing pred %i ", i); DDMN(pred); - } else { printf(" Nothing to do for "); DDMN(pred); } - } - * end Debug output -*/ - /*- Fix the Phi nodes of the current block -*/ for (phi = get_irn_link(b); phi; ) { assert(get_irn_op(phi) == op_Phi); @@ -428,38 +444,6 @@ static void optimize_blocks(ir_node *b, void *env) { } } } - - /* The Phi_pred node is replaced now if it is a Phi. - - Somehow the removed Phi node can be used legally in loops. - Therefore we replace the old phi by the new one. - This must be done _AFTER_ all Phis are optimized, or - it will fail if two Phis use the same pred_Phi. - - FIXME: Is the following true? We ALWAYS replace it by the new one. - - Further we have to remove the old Phi node by replacing it - by Bad. Else it will remain in the keep alive array of End - and cause illegal situations. So if there is no loop, we should - replace it by Bad. - */ - if (get_nodes_block(phi_pred) == pred) { - int i; - /* remove the Phi as it might be kept alive. Further there - might be other users. */ - for (i = ARR_LEN(defers) - 1; i >= 0; --i) { - if (defers[i].phi_pred == phi_pred) - break; - } - if (i < 0) { - /* we have a new replacement */ - defer_ex_phi elem; - - elem.phi_pred = phi_pred; - elem.phi = phi; - ARR_APP1(defer_ex_phi, defers, elem); - } - } } else { /* case Phi 3: */ in[p_preds++] = get_Phi_pred(phi, i); @@ -473,33 +457,37 @@ static void optimize_blocks(ir_node *b, void *env) { exchange(phi, in[0]); else set_irn_in(phi, p_preds, in); + env->changed = 1; phi = get_irn_link(phi); } - /* now, exchange all Phis */ - for (i = ARR_LEN(defers) - 1; i >= 0; --i) { - exchange(defers[i].phi_pred, defers[i].phi); - } - DEL_ARR_F(defers); - /*- This happens only if merge between loop backedge and single loop entry. - See special case above. -*/ + Moreover, it is only needed if predb is the direct dominator of b, else there can be no uses + of the Phi's in predb ... -*/ for (k = 0, n = get_Block_n_cfgpreds(b); k < n; ++k) { - pred = get_nodes_block(get_Block_cfgpred(b, k)); + ir_node *predb = get_nodes_block(get_Block_cfgpred(b, k)); + + if (get_Block_block_visited(predb) + 1 < get_irg_block_visited(current_ir_graph)) { + ir_node *next_phi; - if (get_Block_block_visited(pred) + 1 < get_irg_block_visited(current_ir_graph)) { /* we found a predecessor block at position k that will be removed */ - for (phi = get_irn_link(pred); phi;) { - /* - * the previous phase may already changed the phi, and even - * removed it at all, so check here if this node is still a phi - */ - if (get_irn_op(phi) == op_Phi) { - int q_preds = 0; - - /* move this phi from the predecessor into the block b */ + for (phi = get_irn_link(predb); phi; phi = next_phi) { + int q_preds = 0; + next_phi = get_irn_link(phi); + + assert(is_Phi(phi)); + + if (get_Block_idom(b) != predb) { + /* predb is not the dominator. There can't be uses of pred's Phi nodes, kill them .*/ + exchange(phi, new_Bad()); + } else { + /* predb is the direct dominator of b. There might be uses of the Phi nodes from + predb in further block, so move this phi from the predecessor into the block b */ set_nodes_block(phi, b); + set_irn_link(phi, get_irn_link(b)); + set_irn_link(b, phi); + env->phis_moved = 1; /* first, copy all 0..k-1 predecessors */ for (i = 0; i < k; i++) { @@ -511,9 +499,6 @@ static void optimize_blocks(ir_node *b, void *env) { < get_irg_block_visited(current_ir_graph)) { /* It's an empty block and not yet visited. */ for (j = 0; j < get_Block_n_cfgpreds(pred); j++) { - /* @@@ Hier brauche ich Schleifeninformation!!! Kontrollflusskante - muss Rueckwaertskante sein! (An allen vier in[q_preds] = phi - Anweisungen.) Trotzdem tuts bisher!! */ if (! is_Bad(get_Block_cfgpred(pred, j))) in[q_preds++] = phi; } @@ -552,11 +537,11 @@ static void optimize_blocks(ir_node *b, void *env) { exchange(phi, in[0]); else set_irn_in(phi, q_preds, in); + env->changed = 1; assert(q_preds <= max_preds); // assert(p_preds == q_preds && "Wrong Phi Fix"); } - phi = get_irn_link(phi); } } } @@ -591,19 +576,24 @@ static void optimize_blocks(ir_node *b, void *env) { assert(n_preds <= max_preds); set_irn_in(b, n_preds, in); + env->changed = 1; - assert(get_irn_link(b) == NULL || (n_preds == p_preds && "Wrong Phi Fix")); + assert(get_irn_link(b) == NULL || p_preds == -1 || (n_preds == p_preds && "Wrong Phi Fix")); xfree(in); } /** - * Walker: optimize all blocks using the default optimizations. + * Block walker: optimize all blocks using the default optimizations. * This removes Blocks that with only a Jmp predecessor. */ -static void remove_simple_blocks(ir_node *block, void *env) { +static void remove_simple_blocks(ir_node *block, void *ctx) { ir_node *new_blk = equivalent_node(block); - if (new_blk != block) + merge_env *env = ctx; + + if (new_blk != block) { exchange(block, new_blk); + env->changed = 1; + } } /** @@ -703,9 +693,8 @@ void optimize_cf(ir_graph *irg) { ir_node **in = NULL; ir_node *cond, *end = get_irg_end(irg); ir_graph *rem = current_ir_graph; - irg_dom_state dom_state = get_irg_dom_state(current_ir_graph); - plist_t *list; plist_element_t *el; + merge_env env; assert(get_irg_phase_state(irg) != phase_building); @@ -715,19 +704,18 @@ void optimize_cf(ir_graph *irg) { current_ir_graph = irg; + /* FIXME: is this still needed? */ edges_deactivate(irg); - /* Handle graph state */ - set_irg_outs_inconsistent(current_ir_graph); - set_irg_extblk_inconsistent(current_ir_graph); - set_irg_loopinfo_inconsistent(current_ir_graph); - set_irg_doms_inconsistent(current_ir_graph); + env.changed = 0; + env.phis_moved = 0; - if (dom_state == dom_consistent && get_opt_optimize() && get_opt_unreachable_code()) { + if (get_opt_optimize() && get_opt_unreachable_code()) { ir_node *end; - /* we have dominance info, we can kill dead block */ - irg_block_walk_graph(irg, NULL, remove_dead_block_cf, NULL); + /* kill dead blocks using dom info */ + assure_doms(irg); + irg_block_walk_graph(irg, NULL, remove_dead_block_cf, &env.changed); /* fix the keep-alives */ end = get_irg_end(irg); @@ -735,39 +723,61 @@ void optimize_cf(ir_graph *irg) { ir_node *ka = get_End_keepalive(end, i); if (is_Block(ka)) { - /* do NOT keep dead blocks */ - if (get_Block_dom_depth(ka) < 0) + /* do NOT keep dead blocks */ + if (get_Block_dom_depth(ka) < 0) { set_End_keepalive(end, i, new_Bad()); + env.changed = 1; + } } else if (is_Block_dead(get_nodes_block(ka)) || - get_Block_dom_depth(get_nodes_block(ka)) < 0) + get_Block_dom_depth(get_nodes_block(ka)) < 0) { /* do NOT keep nodes in dead blocks */ set_End_keepalive(end, i, new_Bad()); + env.changed = 1; + } } } - irg_block_walk_graph(irg, NULL, remove_senseless_conds, NULL); + irg_block_walk_graph(irg, NULL, remove_senseless_conds, &env.changed); /* Use block visited flag to mark non-empty blocks. */ inc_irg_block_visited(irg); + set_using_block_visited(irg); + set_using_irn_link(irg); + + env.list = plist_new(); + irg_walk(end, merge_blocks, collect_nodes, &env); - list = plist_new(); - irg_walk(end, merge_blocks, collect_nodes, list); + clear_using_block_visited(irg); + clear_using_irn_link(irg); /* handle all collected switch-Conds */ - foreach_plist(list, el) { + foreach_plist(env.list, el) { cond = plist_element_get_value(el); - handle_switch_cond(cond); + env.changed |= handle_switch_cond(cond); + } + plist_free(env.list); + + 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_loopinfo_inconsistent(irg); } - plist_free(list); /* Optimize the standard code. */ - irg_block_walk(get_irg_end_block(irg), optimize_blocks, remove_simple_blocks, NULL); + env.changed = 0; + assure_doms(irg); + irg_block_walk(get_irg_end_block(irg), optimize_blocks, remove_simple_blocks, &env); /* Walk all keep alives, optimize them if block, add to new in-array for end if useful. */ n = get_End_n_keepalives(end); if (n > 0) NEW_ARR_A(ir_node *, in, n); + + /* in rare cases a node may be kept alive more than once, use the visited flag to detect this */ inc_irg_visited(irg); + set_using_irn_visited(irg); /* fix the keep alive */ for (i = j = 0; i < n; i++) { @@ -777,13 +787,15 @@ void optimize_cf(ir_graph *irg) { ir_op *op = get_irn_op(ka); if ((op == op_Block) && Block_not_block_visited(ka)) { - set_irg_block_visited(irg, /* Don't walk all the way to Start. */ - get_irg_block_visited(irg)-1); - irg_block_walk(ka, optimize_blocks, remove_simple_blocks, NULL); + /* irg_block_walk() will increase the block visited flag, but we must visit only + these blocks that are not visited yet, so decrease it first. */ + set_irg_block_visited(irg, get_irg_block_visited(irg) - 1); + irg_block_walk(ka, optimize_blocks, remove_simple_blocks, &env.changed); mark_irn_visited(ka); in[j++] = ka; } else if (op == op_Phi) { mark_irn_visited(ka); + /* don't keep alive dead blocks */ if (! is_Block_dead(get_nodes_block(ka))) in[j++] = ka; } else if (is_op_keep(op)) { @@ -793,8 +805,61 @@ void optimize_cf(ir_graph *irg) { } } } - if (j != n) + if (j != n) { set_End_keepalives(end, j, in); + env.changed = 1; + } + + clear_using_irn_visited(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. + */ + n = get_End_n_keepalives(end); + if (n > 0) { + if (env.changed) { + /* Handle graph state if was changed. */ + set_irg_outs_inconsistent(irg); + } + assure_irg_outs(irg); + + for (i = j = 0; i < n; ++i) { + ir_node *ka = get_End_keepalive(end, i); + + if (is_Phi(ka)) { + int k; + + for (k = get_irn_n_outs(ka) - 1; k >= 0; --k) { + ir_node *user = get_irn_out(ka, k); + + if (user != ka && user != end) { + /* Is it a real user or just a self loop ? */ + break; + } + } + if (k >= 0) + in[j++] = ka; + } else + in[j++] = ka; + } + if (j != n) { + set_End_keepalives(end, j, in); + env.changed = 1; + } + } + } + + 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_loopinfo_inconsistent(irg); + } + + /* the verifier doesn't work yet with floating nodes */ if (get_irg_pinned(irg) == op_pin_state_pinned) { /* after optimize_cf(), only Bad data flow may remain. */