/* * Copyright (c) 1999, 2025, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "memory/allocation.inline.hpp" #include "opto/addnode.hpp" #include "opto/callnode.hpp" #include "opto/loopnode.hpp" #include "opto/movenode.hpp" #include "opto/node.hpp" #include "opto/opaquenode.hpp" #include "opto/predicates.hpp" //------------------------------split_thru_region------------------------------ // Split Node 'n' through merge point. RegionNode* PhaseIdealLoop::split_thru_region(Node* n, RegionNode* region) { assert(n->is_CFG(), ""); RegionNode* r = new 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 (!at_relevant_ctrl(n, blk1, 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; } } if (clone_cmp_loadklass_down(n, blk1, blk2)) { 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 (clone_cmp_down(n, blk1, blk2)) { return true; } clone_template_assertion_expression_down(n); if (n->Opcode() == Op_OpaqueZeroTripGuard) { // If this Opaque1 is part of the zero trip guard for a loop: // 1- it can't be shared // 2- the zero trip guard can't be the if that's being split // As a consequence, this node could be assigned control anywhere between its current control and the zero trip guard. // Move it down to get it out of the way of split if and avoid breaking the zero trip guard shape. Node* cmp = n->unique_out(); assert(cmp->Opcode() == Op_CmpI, "bad zero trip guard shape"); Node* bol = cmp->unique_out(); assert(bol->Opcode() == Op_Bool, "bad zero trip guard shape"); Node* iff = bol->unique_out(); assert(iff->Opcode() == Op_If, "bad zero trip guard shape"); set_ctrl(n, iff->in(0)); set_ctrl(cmp, iff->in(0)); set_ctrl(bol, iff->in(0)); 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); } } // ConvI2L may have type information on it which becomes invalid if // it moves up in the graph so change any clones so widen the type // to TypeLong::INT when pushing it up. const Type* rtype = nullptr; if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::INT) { rtype = TypeLong::INT; } // 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(); // Widen the type of the ConvI2L when pushing up. if (rtype != nullptr) x->as_Type()->set_type(rtype); 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.replace_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; } // Look for a (If .. (Bool(CmpP (LoadKlass .. (AddP obj ..)) ..))) and clone all of it down. // There's likely a CheckCastPP on one of the branches of the If, with obj as input. // If the (LoadKlass .. (AddP obj ..)) is not cloned down, then split if transforms this to: (If .. (Bool(CmpP phi1 ..))) // and the CheckCastPP to (CheckCastPP phi2). It's possible then that phi2 is transformed to a CheckCastPP // (through PhiNode::Ideal) and that that CheckCastPP is replaced by another narrower CheckCastPP at the same control // (through ConstraintCastNode::Identity). That could cause the CheckCastPP at the If to become top while (CmpP phi1) // wouldn't constant fold because it's using a different data path. Cloning the whole subgraph down guarantees both the // AddP and CheckCastPP have the same obj input after split if. bool PhaseIdealLoop::clone_cmp_loadklass_down(Node* n, const Node* blk1, const Node* blk2) { if (n->Opcode() == Op_AddP && at_relevant_ctrl(n, blk1, blk2)) { Node_List cmp_nodes; uint old = C->unique(); for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { Node* u1 = n->fast_out(i); if (u1->Opcode() == Op_LoadNKlass && at_relevant_ctrl(u1, blk1, blk2)) { for (DUIterator_Fast jmax, j = u1->fast_outs(jmax); j < jmax; j++) { Node* u2 = u1->fast_out(j); if (u2->Opcode() == Op_DecodeNKlass && at_relevant_ctrl(u2, blk1, blk2)) { for (DUIterator k = u2->outs(); u2->has_out(k); k++) { Node* u3 = u2->out(k); if (at_relevant_ctrl(u3, blk1, blk2) && clone_cmp_down(u3, blk1, blk2)) { --k; } } for (DUIterator_Fast kmax, k = u2->fast_outs(kmax); k < kmax; k++) { Node* u3 = u2->fast_out(k); if (u3->_idx >= old) { cmp_nodes.push(u3); } } } } } else if (u1->Opcode() == Op_LoadKlass && at_relevant_ctrl(u1, blk1, blk2)) { for (DUIterator j = u1->outs(); u1->has_out(j); j++) { Node* u2 = u1->out(j); if (at_relevant_ctrl(u2, blk1, blk2) && clone_cmp_down(u2, blk1, blk2)) { --j; } } for (DUIterator_Fast kmax, k = u1->fast_outs(kmax); k < kmax; k++) { Node* u2 = u1->fast_out(k); if (u2->_idx >= old) { cmp_nodes.push(u2); } } } } for (uint i = 0; i < cmp_nodes.size(); ++i) { Node* cmp = cmp_nodes.at(i); clone_loadklass_nodes_at_cmp_index(n, cmp, 1); clone_loadklass_nodes_at_cmp_index(n, cmp, 2); } if (n->outcnt() == 0) { assert(n->is_dead(), ""); return true; } } return false; } bool PhaseIdealLoop::at_relevant_ctrl(Node* n, const Node* blk1, const Node* blk2) { return ctrl_or_self(n) == blk1 || ctrl_or_self(n) == blk2; } void PhaseIdealLoop::clone_loadklass_nodes_at_cmp_index(const Node* n, Node* cmp, int i) { Node* decode = cmp->in(i); if (decode->Opcode() == Op_DecodeNKlass) { Node* loadklass = decode->in(1); if (loadklass->Opcode() == Op_LoadNKlass) { Node* addp = loadklass->in(MemNode::Address); if (addp == n) { Node* ctrl = get_ctrl(cmp); Node* decode_clone = decode->clone(); Node* loadklass_clone = loadklass->clone(); Node* addp_clone = addp->clone(); register_new_node(decode_clone, ctrl); register_new_node(loadklass_clone, ctrl); register_new_node(addp_clone, ctrl); _igvn.replace_input_of(cmp, i, decode_clone); _igvn.replace_input_of(decode_clone, 1, loadklass_clone); _igvn.replace_input_of(loadklass_clone, MemNode::Address, addp_clone); if (decode->outcnt() == 0) { _igvn.remove_dead_node(decode); } } } } else { Node* loadklass = cmp->in(i); if (loadklass->Opcode() == Op_LoadKlass) { Node* addp = loadklass->in(MemNode::Address); if (addp == n) { Node* ctrl = get_ctrl(cmp); Node* loadklass_clone = loadklass->clone(); Node* addp_clone = addp->clone(); register_new_node(loadklass_clone, ctrl); register_new_node(addp_clone, ctrl); _igvn.replace_input_of(cmp, i, loadklass_clone); _igvn.replace_input_of(loadklass_clone, MemNode::Address, addp_clone); if (loadklass->outcnt() == 0) { _igvn.remove_dead_node(loadklass); } } } } } bool PhaseIdealLoop::clone_cmp_down(Node* n, const Node* blk1, const Node* blk2) { 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()) && (at_relevant_ctrl(bol, blk1, blk2) && bol->outcnt() == 1 && bol->unique_out()->is_CMove() && (cmov = bol->unique_out()->as_CMove()) && at_relevant_ctrl(cmov, blk1, blk2)))) { // Must clone down if (!n->is_FastLock()) { // 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(); if (use->is_OpaqueNotNull() || use->is_OpaqueTemplateAssertionPredicate() || use->is_OpaqueInitializedAssertionPredicate()) { if (use->outcnt() == 1) { Node* iff = use->unique_out(); assert(iff->is_If(), "unexpected node type"); Node *use_c = iff->in(0); if (use_c == blk1 || use_c == blk2) { continue; } } } else { // We might see an Opaque1 from a loop limit check here assert(use->is_If() || use->is_CMove() || use->Opcode() == Op_Opaque1 || use->is_AllocateArray(), "unexpected node type"); Node *use_c = (use->is_If() || use->is_AllocateArray()) ? use->in(0) : get_ctrl(use); if (use_c == blk1 || use_c == blk2) { assert(use->is_CMove(), "unexpected node type"); continue; } } } if (at_relevant_ctrl(bol, blk1, blk2)) { // Recursively sink any BoolNode for (DUIterator j = bol->outs(); bol->has_out(j); j++) { Node* u = bol->out(j); // Uses are either IfNodes, CMoves, OpaqueNotNull, or Opaque*AssertionPredicate if (u->is_OpaqueNotNull() || u->is_OpaqueTemplateAssertionPredicate() || u->is_OpaqueInitializedAssertionPredicate()) { assert(u->in(1) == bol, "bad input"); for (DUIterator_Last kmin, k = u->last_outs(kmin); k >= kmin; --k) { Node* iff = u->last_out(k); assert(iff->is_If() || iff->is_CMove(), "unexpected node type"); assert( iff->in(1) == u, "" ); // Get control block of either the CMove or the If input Node *iff_ctrl = iff->is_If() ? iff->in(0) : get_ctrl(iff); Node *x1 = bol->clone(); Node *x2 = u->clone(); register_new_node(x1, iff_ctrl); register_new_node(x2, iff_ctrl); _igvn.replace_input_of(x2, 1, x1); _igvn.replace_input_of(iff, 1, x2); } _igvn.remove_dead_node(u); --j; } else { // We might see an Opaque1 from a loop limit check here assert(u->is_If() || u->is_CMove() || u->Opcode() == Op_Opaque1 || u->is_AllocateArray(), "unexpected node type"); assert(u->is_AllocateArray() || u->in(1) == bol, ""); assert(!u->is_AllocateArray() || u->in(AllocateNode::ValidLengthTest) == bol, "wrong input to AllocateArray"); // Get control block of either the CMove or the If input Node *u_ctrl = (u->is_If() || u->is_AllocateArray()) ? u->in(0) : get_ctrl(u); assert((u_ctrl != blk1 && u_ctrl != blk2) || u->is_CMove(), "won't converge"); Node *x = bol->clone(); register_new_node(x, u_ctrl); _igvn.replace_input_of(u, u->is_AllocateArray() ? AllocateNode::ValidLengthTest : 1, x); --j; } } _igvn.remove_dead_node(bol); --i; } } } // Clone down this CmpNode for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; --j) { Node* use = n->last_out(j); uint pos = 1; if (n->is_FastLock()) { pos = TypeFunc::Parms + 2; assert(use->is_Lock(), "FastLock only used by LockNode"); } assert(use->in(pos) == n, "" ); Node *x = n->clone(); register_new_node(x, ctrl_or_self(use)); _igvn.replace_input_of(use, pos, x); } _igvn.remove_dead_node(n); return true; } } return false; } // 'n' could be a node belonging to a Template Assertion Expression (i.e. any node between a Template Assertion Predicate // and its OpaqueLoop* nodes (included)). We cannot simply split this node up since this would create a phi node inside // the Template Assertion Expression - making it unrecognizable as such. Therefore, we completely clone the entire // Template Assertion Expression "down". This ensures that we have an untouched copy that is still recognized by the // Template Assertion Predicate matching code. void PhaseIdealLoop::clone_template_assertion_expression_down(Node* node) { if (!TemplateAssertionExpressionNode::is_in_expression(node)) { return; } TemplateAssertionExpressionNode template_assertion_expression_node(node); auto clone_expression = [&](IfNode* template_assertion_predicate) { OpaqueTemplateAssertionPredicateNode* opaque_node = template_assertion_predicate->in(1)->as_OpaqueTemplateAssertionPredicate(); TemplateAssertionExpression template_assertion_expression(opaque_node, this); Node* new_control = template_assertion_predicate->in(0); OpaqueTemplateAssertionPredicateNode* cloned_opaque_node = template_assertion_expression.clone(new_control, opaque_node->loop_node()); igvn().replace_input_of(template_assertion_predicate, 1, cloned_opaque_node); }; template_assertion_expression_node.for_each_template_assertion_predicate(clone_expression); } //------------------------------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*)((intptr_t)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(&_igvn); phi_post = t; } else { register_new_node( phi_post, prior_n ); } } } // Update cache everywhere prior_n = (Node*)((intptr_t)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 == nullptr) { // He's dead, Jim _igvn.replace_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.replace_input_of(use, i, new_def); } //------------------------------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, RegionNode** new_false_region, RegionNode** new_true_region) { C->set_major_progress(); RegionNode *region = iff->in(0)->as_Region(); 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 (_loop_or_ctrl[m->_idx] == nullptr) { _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. RegionNode *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 = nullptr, *old_true = nullptr; RegionNode* new_false = nullptr; RegionNode* new_true = nullptr; 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); RegionNode* 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(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); lazy_update(region, region_dom); // idom must be update before handle_uses region->set_req(0, nullptr); // Break the self-cycle. Required for lazy_update to work on region // 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 k = region->outs(); region->has_out(k); k++) { Node* phi = region->out(k); if (!phi->in(0)) { // Dead phi? Remove it _igvn.remove_dead_node(phi); } else if (phi == region) { // Found the self-reference continue; // No roll-back of DUIterator } else if (phi->is_Phi()) { // Expected common case: Phi hanging off of Region assert(phi->in(0) == region, "Inconsistent graph"); // 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 // Remove the dead Phi _igvn.remove_dead_node( phi ); } else { assert(phi->in(0) == region, "Inconsistent graph"); // 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); } // Every path above deletes a use of the region, except for the region // self-cycle (which is needed by handle_use calling find_use_block // calling get_ctrl calling get_ctrl_no_update looking for dead // regions). So roll back the DUIterator innards. --k; } // End of while merge point has phis _igvn.remove_dead_node(region); if (iff->Opcode() == Op_RangeCheck) { // Pin array access nodes: control is updated here to a region. If, after some transformations, only one path // into the region is left, an array load could become dependent on a condition that's not a range check for // that access. If that condition is replaced by an identical dominating one, then an unpinned load would risk // floating above its range check. pin_array_access_nodes_dependent_on(new_true); pin_array_access_nodes_dependent_on(new_false); } if (new_false_region != nullptr) { *new_false_region = new_false; } if (new_true_region != nullptr) { *new_true_region = new_true; } DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } ); } void PhaseIdealLoop::pin_array_access_nodes_dependent_on(Node* ctrl) { for (DUIterator i = ctrl->outs(); ctrl->has_out(i); i++) { Node* use = ctrl->out(i); if (!use->depends_only_on_test()) { continue; } Node* pinned_clone = use->pin_array_access_node(); if (pinned_clone != nullptr) { register_new_node_with_ctrl_of(pinned_clone, use); _igvn.replace_node(use, pinned_clone); --i; } } }