diff -r 000000000000 -r a61af66fc99e src/share/vm/opto/split_if.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/opto/split_if.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,536 @@ +/* + * Copyright 1999-2006 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +#include "incls/_precompiled.incl" +#include "incls/_split_if.cpp.incl" + + +//------------------------------split_thru_region------------------------------ +// Split Node 'n' through merge point. +Node *PhaseIdealLoop::split_thru_region( Node *n, Node *region ) { + uint wins = 0; + assert( n->is_CFG(), "" ); + assert( region->is_Region(), "" ); + Node *r = new (C, region->req()) RegionNode( region->req() ); + IdealLoopTree *loop = get_loop( n ); + for( uint i = 1; i < region->req(); i++ ) { + Node *x = n->clone(); + Node *in0 = n->in(0); + if( in0->in(0) == region ) x->set_req( 0, in0->in(i) ); + for( uint j = 1; j < n->req(); j++ ) { + Node *in = n->in(j); + if( get_ctrl(in) == region ) + x->set_req( j, in->in(i) ); + } + _igvn.register_new_node_with_optimizer(x); + set_loop(x, loop); + set_idom(x, x->in(0), dom_depth(x->in(0))+1); + r->init_req(i, x); + } + + // Record region + r->set_req(0,region); // Not a TRUE RegionNode + _igvn.register_new_node_with_optimizer(r); + set_loop(r, loop); + if( !loop->_child ) + loop->_body.push(r); + return r; +} + +//------------------------------split_up--------------------------------------- +// Split block-local op up through the phis to empty the current block +bool PhaseIdealLoop::split_up( Node *n, Node *blk1, Node *blk2 ) { + if( n->is_CFG() ) { + assert( n->in(0) != blk1, "Lousy candidate for split-if" ); + return false; + } + if( get_ctrl(n) != blk1 && get_ctrl(n) != blk2 ) + return false; // Not block local + if( n->is_Phi() ) return false; // Local PHIs are expected + + // Recursively split-up inputs + for (uint i = 1; i < n->req(); i++) { + if( split_up( n->in(i), blk1, blk2 ) ) { + // Got split recursively and self went dead? + if (n->outcnt() == 0) + _igvn.remove_dead_node(n); + return true; + } + } + + // Check for needing to clone-up a compare. Can't do that, it forces + // another (nested) split-if transform. Instead, clone it "down". + if( n->is_Cmp() ) { + assert(get_ctrl(n) == blk2 || get_ctrl(n) == blk1, "must be in block with IF"); + // Check for simple Cmp/Bool/CMove which we can clone-up. Cmp/Bool/CMove + // sequence can have no other users and it must all reside in the split-if + // block. Non-simple Cmp/Bool/CMove sequences are 'cloned-down' below - + // private, per-use versions of the Cmp and Bool are made. These sink to + // the CMove block. If the CMove is in the split-if block, then in the + // next iteration this will become a simple Cmp/Bool/CMove set to clone-up. + Node *bol, *cmov; + if( !(n->outcnt() == 1 && n->unique_out()->is_Bool() && + (bol = n->unique_out()->as_Bool()) && + (get_ctrl(bol) == blk1 || + get_ctrl(bol) == blk2) && + bol->outcnt() == 1 && + bol->unique_out()->is_CMove() && + (cmov = bol->unique_out()->as_CMove()) && + (get_ctrl(cmov) == blk1 || + get_ctrl(cmov) == blk2) ) ) { + + // Must clone down +#ifndef PRODUCT + if( PrintOpto && VerifyLoopOptimizations ) { + tty->print("Cloning down: "); + n->dump(); + } +#endif + // Clone down any block-local BoolNode uses of this CmpNode + for (DUIterator i = n->outs(); n->has_out(i); i++) { + Node* bol = n->out(i); + assert( bol->is_Bool(), "" ); + if (bol->outcnt() == 1) { + Node* use = bol->unique_out(); + Node *use_c = use->is_If() ? use->in(0) : get_ctrl(use); + if (use_c == blk1 || use_c == blk2) { + continue; + } + } + if (get_ctrl(bol) == blk1 || get_ctrl(bol) == blk2) { + // Recursively sink any BoolNode +#ifndef PRODUCT + if( PrintOpto && VerifyLoopOptimizations ) { + tty->print("Cloning down: "); + bol->dump(); + } +#endif + for (DUIterator_Last jmin, j = bol->last_outs(jmin); j >= jmin; --j) { + // Uses are either IfNodes or CMoves + Node* iff = bol->last_out(j); + assert( iff->in(1) == bol, "" ); + // Get control block of either the CMove or the If input + Node *iff_ctrl = iff->is_If() ? iff->in(0) : get_ctrl(iff); + Node *x = bol->clone(); + register_new_node(x, iff_ctrl); + _igvn.hash_delete(iff); + iff->set_req(1, x); + _igvn._worklist.push(iff); + } + _igvn.remove_dead_node( bol ); + --i; + } + } + // Clone down this CmpNode + for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; --j) { + Node* bol = n->last_out(j); + assert( bol->in(1) == n, "" ); + Node *x = n->clone(); + register_new_node(x, get_ctrl(bol)); + _igvn.hash_delete(bol); + bol->set_req(1, x); + _igvn._worklist.push(bol); + } + _igvn.remove_dead_node( n ); + + return true; + } + } + + // See if splitting-up a Store. Any anti-dep loads must go up as + // well. An anti-dep load might be in the wrong block, because in + // this particular layout/schedule we ignored anti-deps and allow + // memory to be alive twice. This only works if we do the same + // operations on anti-dep loads as we do their killing stores. + if( n->is_Store() && n->in(MemNode::Memory)->in(0) == n->in(0) ) { + // Get store's memory slice + int alias_idx = C->get_alias_index(_igvn.type(n->in(MemNode::Address))->is_ptr()); + + // Get memory-phi anti-dep loads will be using + Node *memphi = n->in(MemNode::Memory); + assert( memphi->is_Phi(), "" ); + // Hoist any anti-dep load to the splitting block; + // it will then "split-up". + for (DUIterator_Fast imax,i = memphi->fast_outs(imax); i < imax; i++) { + Node *load = memphi->fast_out(i); + if( load->is_Load() && alias_idx == C->get_alias_index(_igvn.type(load->in(MemNode::Address))->is_ptr()) ) + set_ctrl(load,blk1); + } + } + + // Found some other Node; must clone it up +#ifndef PRODUCT + if( PrintOpto && VerifyLoopOptimizations ) { + tty->print("Cloning up: "); + n->dump(); + } +#endif + + // Now actually split-up this guy. One copy per control path merging. + Node *phi = PhiNode::make_blank(blk1, n); + for( uint j = 1; j < blk1->req(); j++ ) { + Node *x = n->clone(); + if( n->in(0) && n->in(0) == blk1 ) + x->set_req( 0, blk1->in(j) ); + for( uint i = 1; i < n->req(); i++ ) { + Node *m = n->in(i); + if( get_ctrl(m) == blk1 ) { + assert( m->in(0) == blk1, "" ); + x->set_req( i, m->in(j) ); + } + } + register_new_node( x, blk1->in(j) ); + phi->init_req( j, x ); + } + // Announce phi to optimizer + register_new_node(phi, blk1); + + // Remove cloned-up value from optimizer; use phi instead + _igvn.hash_delete(n); + _igvn.subsume_node( n, phi ); + + // (There used to be a self-recursive call to split_up() here, + // but it is not needed. All necessary forward walking is done + // by do_split_if() below.) + + return true; +} + +//------------------------------register_new_node------------------------------ +void PhaseIdealLoop::register_new_node( Node *n, Node *blk ) { + _igvn.register_new_node_with_optimizer(n); + set_ctrl(n, blk); + IdealLoopTree *loop = get_loop(blk); + if( !loop->_child ) + loop->_body.push(n); +} + +//------------------------------small_cache------------------------------------ +struct small_cache : public Dict { + + small_cache() : Dict( cmpkey, hashptr ) {} + Node *probe( Node *use_blk ) { return (Node*)((*this)[use_blk]); } + void lru_insert( Node *use_blk, Node *new_def ) { Insert(use_blk,new_def); } +}; + +//------------------------------spinup----------------------------------------- +// "Spin up" the dominator tree, starting at the use site and stopping when we +// find the post-dominating point. + +// We must be at the merge point which post-dominates 'new_false' and +// 'new_true'. Figure out which edges into the RegionNode eventually lead up +// to false and which to true. Put in a PhiNode to merge values; plug in +// the appropriate false-arm or true-arm values. If some path leads to the +// original IF, then insert a Phi recursively. +Node *PhaseIdealLoop::spinup( Node *iff_dom, Node *new_false, Node *new_true, Node *use_blk, Node *def, small_cache *cache ) { + if (use_blk->is_top()) // Handle dead uses + return use_blk; + Node *prior_n = (Node*)0xdeadbeef; + Node *n = use_blk; // Get path input + assert( use_blk != iff_dom, "" ); + // Here's the "spinup" the dominator tree loop. Do a cache-check + // along the way, in case we've come this way before. + while( n != iff_dom ) { // Found post-dominating point? + prior_n = n; + n = idom(n); // Search higher + Node *s = cache->probe( prior_n ); // Check cache + if( s ) return s; // Cache hit! + } + + Node *phi_post; + if( prior_n == new_false || prior_n == new_true ) { + phi_post = def->clone(); + phi_post->set_req(0, prior_n ); + register_new_node(phi_post, prior_n); + } else { + // This method handles both control uses (looking for Regions) or data + // uses (looking for Phis). If looking for a control use, then we need + // to insert a Region instead of a Phi; however Regions always exist + // previously (the hash_find_insert below would always hit) so we can + // return the existing Region. + if( def->is_CFG() ) { + phi_post = prior_n; // If looking for CFG, return prior + } else { + assert( def->is_Phi(), "" ); + assert( prior_n->is_Region(), "must be a post-dominating merge point" ); + + // Need a Phi here + phi_post = PhiNode::make_blank(prior_n, def); + // Search for both true and false on all paths till find one. + for( uint i = 1; i < phi_post->req(); i++ ) // For all paths + phi_post->init_req( i, spinup( iff_dom, new_false, new_true, prior_n->in(i), def, cache ) ); + Node *t = _igvn.hash_find_insert(phi_post); + if( t ) { // See if we already have this one + // phi_post will not be used, so kill it + _igvn.remove_dead_node(phi_post); + phi_post->destruct(); + phi_post = t; + } else { + register_new_node( phi_post, prior_n ); + } + } + } + + // Update cache everywhere + prior_n = (Node*)0xdeadbeef; // Reset IDOM walk + n = use_blk; // Get path input + // Spin-up the idom tree again, basically doing path-compression. + // Insert cache entries along the way, so that if we ever hit this + // point in the IDOM tree again we'll stop immediately on a cache hit. + while( n != iff_dom ) { // Found post-dominating point? + prior_n = n; + n = idom(n); // Search higher + cache->lru_insert( prior_n, phi_post ); // Fill cache + } // End of while not gone high enough + + return phi_post; +} + +//------------------------------find_use_block--------------------------------- +// Find the block a USE is in. Normally USE's are in the same block as the +// using instruction. For Phi-USE's, the USE is in the predecessor block +// along the corresponding path. +Node *PhaseIdealLoop::find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ) { + // CFG uses are their own block + if( use->is_CFG() ) + return use; + + if( use->is_Phi() ) { // Phi uses in prior block + // Grab the first Phi use; there may be many. + // Each will be handled as a seperate iteration of + // the "while( phi->outcnt() )" loop. + uint j; + for( j = 1; j < use->req(); j++ ) + if( use->in(j) == def ) + break; + assert( j < use->req(), "def should be among use's inputs" ); + return use->in(0)->in(j); + } + // Normal (non-phi) use + Node *use_blk = get_ctrl(use); + // Some uses are directly attached to the old (and going away) + // false and true branches. + if( use_blk == old_false ) { + use_blk = new_false; + set_ctrl(use, new_false); + } + if( use_blk == old_true ) { + use_blk = new_true; + set_ctrl(use, new_true); + } + + if (use_blk == NULL) { // He's dead, Jim + _igvn.hash_delete(use); + _igvn.subsume_node(use, C->top()); + } + + return use_blk; +} + +//------------------------------handle_use------------------------------------- +// Handle uses of the merge point. Basically, split-if makes the merge point +// go away so all uses of the merge point must go away as well. Most block +// local uses have already been split-up, through the merge point. Uses from +// far below the merge point can't always be split up (e.g., phi-uses are +// pinned) and it makes too much stuff live. Instead we use a path-based +// solution to move uses down. +// +// If the use is along the pre-split-CFG true branch, then the new use will +// be from the post-split-CFG true merge point. Vice-versa for the false +// path. Some uses will be along both paths; then we sink the use to the +// post-dominating location; we may need to insert a Phi there. +void PhaseIdealLoop::handle_use( Node *use, Node *def, small_cache *cache, Node *region_dom, Node *new_false, Node *new_true, Node *old_false, Node *old_true ) { + + Node *use_blk = find_use_block(use,def,old_false,new_false,old_true,new_true); + if( !use_blk ) return; // He's dead, Jim + + // Walk up the dominator tree until I hit either the old IfFalse, the old + // IfTrue or the old If. Insert Phis where needed. + Node *new_def = spinup( region_dom, new_false, new_true, use_blk, def, cache ); + + // Found where this USE goes. Re-point him. + uint i; + for( i = 0; i < use->req(); i++ ) + if( use->in(i) == def ) + break; + assert( i < use->req(), "def should be among use's inputs" ); + _igvn.hash_delete(use); + use->set_req(i, new_def); + _igvn._worklist.push(use); +} + +//------------------------------do_split_if------------------------------------ +// Found an If getting its condition-code input from a Phi in the same block. +// Split thru the Region. +void PhaseIdealLoop::do_split_if( Node *iff ) { +#ifndef PRODUCT + if( PrintOpto && VerifyLoopOptimizations ) + tty->print_cr("Split-if"); +#endif + C->set_major_progress(); + Node *region = iff->in(0); + Node *region_dom = idom(region); + + // We are going to clone this test (and the control flow with it) up through + // the incoming merge point. We need to empty the current basic block. + // Clone any instructions which must be in this block up through the merge + // point. + DUIterator i, j; + bool progress = true; + while (progress) { + progress = false; + for (i = region->outs(); region->has_out(i); i++) { + Node* n = region->out(i); + if( n == region ) continue; + // The IF to be split is OK. + if( n == iff ) continue; + if( !n->is_Phi() ) { // Found pinned memory op or such + if (split_up(n, region, iff)) { + i = region->refresh_out_pos(i); + progress = true; + } + continue; + } + assert( n->in(0) == region, "" ); + + // Recursively split up all users of a Phi + for (j = n->outs(); n->has_out(j); j++) { + Node* m = n->out(j); + // If m is dead, throw it away, and declare progress + if (_nodes[m->_idx] == NULL) { + _igvn.remove_dead_node(m); + // fall through + } + else if (m != iff && split_up(m, region, iff)) { + // fall through + } else { + continue; + } + // Something unpredictable changed. + // Tell the iterators to refresh themselves, and rerun the loop. + i = region->refresh_out_pos(i); + j = region->refresh_out_pos(j); + progress = true; + } + } + } + + // Now we have no instructions in the block containing the IF. + // Split the IF. + Node *new_iff = split_thru_region( iff, region ); + + // Replace both uses of 'new_iff' with Regions merging True/False + // paths. This makes 'new_iff' go dead. + Node *old_false, *old_true; + Node *new_false, *new_true; + for (DUIterator_Last j2min, j2 = iff->last_outs(j2min); j2 >= j2min; --j2) { + Node *ifp = iff->last_out(j2); + assert( ifp->Opcode() == Op_IfFalse || ifp->Opcode() == Op_IfTrue, "" ); + ifp->set_req(0, new_iff); + Node *ifpx = split_thru_region( ifp, region ); + + // Replace 'If' projection of a Region with a Region of + // 'If' projections. + ifpx->set_req(0, ifpx); // A TRUE RegionNode + + // Setup dominator info + set_idom(ifpx, region_dom, dom_depth(region_dom) + 1); + + // Check for splitting loop tails + if( get_loop(iff)->tail() == ifp ) + get_loop(iff)->_tail = ifpx; + + // Replace in the graph with lazy-update mechanism + new_iff->set_req(0, new_iff); // hook self so it does not go dead + lazy_replace_proj( ifp, ifpx ); + new_iff->set_req(0, region); + + // Record bits for later xforms + if( ifp->Opcode() == Op_IfFalse ) { + old_false = ifp; + new_false = ifpx; + } else { + old_true = ifp; + new_true = ifpx; + } + } + _igvn.remove_dead_node(new_iff); + // Lazy replace IDOM info with the region's dominator + lazy_replace( iff, region_dom ); + + // Now make the original merge point go dead, by handling all its uses. + small_cache region_cache; + // Preload some control flow in region-cache + region_cache.lru_insert( new_false, new_false ); + region_cache.lru_insert( new_true , new_true ); + // Now handle all uses of the splitting block + for (DUIterator_Last kmin, k = region->last_outs(kmin); k >= kmin; --k) { + Node* phi = region->last_out(k); + if( !phi->in(0) ) { // Dead phi? Remove it + _igvn.remove_dead_node(phi); + continue; + } + assert( phi->in(0) == region, "" ); + if( phi == region ) { // Found the self-reference + phi->set_req(0, NULL); + continue; // Break the self-cycle + } + // Expected common case: Phi hanging off of Region + if( phi->is_Phi() ) { + // Need a per-def cache. Phi represents a def, so make a cache + small_cache phi_cache; + + // Inspect all Phi uses to make the Phi go dead + for (DUIterator_Last lmin, l = phi->last_outs(lmin); l >= lmin; --l) { + Node* use = phi->last_out(l); + // Compute the new DEF for this USE. New DEF depends on the path + // taken from the original DEF to the USE. The new DEF may be some + // collection of PHI's merging values from different paths. The Phis + // inserted depend only on the location of the USE. We use a + // 2-element cache to handle multiple uses from the same block. + handle_use( use, phi, &phi_cache, region_dom, new_false, new_true, old_false, old_true ); + } // End of while phi has uses + + // Because handle_use might relocate region->_out, + // we must refresh the iterator. + k = region->last_outs(kmin); + + // Remove the dead Phi + _igvn.remove_dead_node( phi ); + + } else { + // Random memory op guarded by Region. Compute new DEF for USE. + handle_use( phi, region, ®ion_cache, region_dom, new_false, new_true, old_false, old_true ); + } + + } // End of while merge point has phis + + // Any leftover bits in the splitting block must not have depended on local + // Phi inputs (these have already been split-up). Hence it's safe to hoist + // these guys to the dominating point. + lazy_replace( region, region_dom ); +#ifndef PRODUCT + if( VerifyLoopOptimizations ) verify(); +#endif +}