/* * 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 ) { assert(!n->is_CFG(), "must be data node"); _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 separate 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 }