CoCalc -- J9CFGSimplifier.cpp

GitHub Repository: PojavLauncherTeam/openj9
Path: blob/master/runtime/compiler/optimizer/J9CFGSimplifier.cpp
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/*******************************************************************************
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 * Copyright (c) 2019, 2020 IBM Corp. and others
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 *
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 * This program and the accompanying materials are made available under
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 * the terms of the Eclipse Public License 2.0 which accompanies this
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 * distribution and is available at https://www.eclipse.org/legal/epl-2.0/
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 * or the Apache License, Version 2.0 which accompanies this distribution and
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 * is available at https://www.apache.org/licenses/LICENSE-2.0.
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 *
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 * This Source Code may also be made available under the following
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 * Secondary Licenses when the conditions for such availability set
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 * forth in the Eclipse Public License, v. 2.0 are satisfied: GNU
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 * General Public License, version 2 with the GNU Classpath
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 * Exception [1] and GNU General Public License, version 2 with the
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 * OpenJDK Assembly Exception [2].
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 *
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 * [1] https://www.gnu.org/software/classpath/license.html
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 * [2] http://openjdk.java.net/legal/assembly-exception.html
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 *
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 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0 WITH Classpath-exception-2.0 OR LicenseRef-GPL-2.0 WITH Assembly-exception
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 *******************************************************************************/
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#include "compile/Method.hpp"
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#include "optimizer/CFGSimplifier.hpp"
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#include "optimizer/Optimization_inlines.hpp"
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#include "optimizer/TransformUtil.hpp"
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#include "il/Block.hpp"
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#include "il/Node.hpp"
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#include "il/Node_inlines.hpp"
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#include "il/StaticSymbol.hpp"
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#include "il/Symbol.hpp"
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#define OPT_DETAILS "O^O CFG SIMPLIFICATION: "
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bool J9::CFGSimplifier::simplifyIfPatterns(bool needToDuplicateTree)
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   {
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   static char *enableCFGSimplification = feGetEnv("TR_enableCFGSimplificaiton");
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   if (enableCFGSimplification == NULL)
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      return false;
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   return OMR::CFGSimplifier::simplifyIfPatterns(needToDuplicateTree)
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          || simplifyResolvedRequireNonNull(needToDuplicateTree)
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          || simplifyUnresolvedRequireNonNull(needToDuplicateTree)
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          ;
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   }
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// Look for pattern of the form:
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//
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// ifacmpeq block_A
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//   ... some ref
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//   aconst NULL
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//
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// OR
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//
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// ifacmpne block_A
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//   ... some ref
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//   aconst NULL
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//
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// Where block_A looks like:
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// ResolveCHK
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//    loadaddr
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// treetop
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//    new
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//       => loadaddr
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// ResolveAndNULLCHK
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//    call java/lang/NullPointerException.<init>();
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//       => new
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// NULLCHK
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//    athrow
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//       => new
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bool J9::CFGSimplifier::simplifyUnresolvedRequireNonNull(bool needToDuplicateTree)
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   {
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   static char *disableSimplifyExplicitNULLTest = feGetEnv("TR_disableSimplifyExplicitNULLTest");
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   static char *disableSimplifyUnresolvedRequireNonNull = feGetEnv("TR_disableSimplifyUnresolvedRequireNonNull");
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   if (disableSimplifyExplicitNULLTest != NULL || disableSimplifyUnresolvedRequireNonNull != NULL)
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      return false;
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   if (comp()->getOSRMode() == TR::involuntaryOSR)
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         return false;
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   if (trace())
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      traceMsg(comp(), "Start simplifyUnresolvedRequireNonNull\n");
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   // This block must end in an ifacmpeq or ifacmpne against aconst NULLa
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   TR::TreeTop *compareTreeTop = getLastRealTreetop(_block);
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   TR::Node *compareNode       = compareTreeTop->getNode();
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   if (compareNode->getOpCodeValue() != TR::ifacmpeq
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       && compareNode->getOpCodeValue() != TR::ifacmpne)
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      return false;
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   if (trace())
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      traceMsg(comp(), "   Found an ifacmp[eq/ne] n%dn\n", compareNode->getGlobalIndex());
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   if (compareNode->getSecondChild()->getOpCodeValue() != TR::aconst
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       || compareNode->getSecondChild()->getAddress() != 0)
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      return false;
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   // _next1 is fall through so grab the block where the value is NULL
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   TR::Block *nullBlock = compareNode->getOpCodeValue() == TR::ifacmpeq ? _next2 : _next1;
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   TR::Block *nonnullBlock = compareNode->getOpCodeValue() == TR::ifacmpeq ? _next1 : _next2;
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   if (trace())
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      traceMsg(comp(), "  Matched nullBlock %d\n", nullBlock->getNumber());
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   TR::TreeTop *nullBlockCursor = nullBlock->getEntry()->getNextTreeTop();
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   if (nullBlockCursor->getNode()->getOpCodeValue() != TR::ResolveCHK
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       || nullBlockCursor->getNode()->getFirstChild()->getOpCodeValue() != TR::loadaddr)
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      return false;
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   if (trace())
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      traceMsg(comp(), "   Match ResolveCHK of loadaddr\n");
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   TR::Node *loadaddr = nullBlockCursor->getNode()->getFirstChild();
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   nullBlockCursor = nullBlockCursor->getNextTreeTop();
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   if (nullBlockCursor->getNode()->getOpCodeValue() != TR::treetop
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       || nullBlockCursor->getNode()->getFirstChild()->getOpCodeValue() != TR::New
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       || nullBlockCursor->getNode()->getFirstChild()->getFirstChild() != loadaddr)
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      return false;
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   TR::Node *exceptionNode = nullBlockCursor->getNode()->getFirstChild();
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   if (trace())
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      traceMsg(comp(), "   Matched new of loadaddr\n");
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   nullBlockCursor = nullBlockCursor->getNextTreeTop();
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   // optionally match pending push store
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   if (nullBlockCursor->getNode()->getOpCodeValue() == TR::astore
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       && nullBlockCursor->getNode()->getFirstChild() == exceptionNode
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       && nullBlockCursor->getNode()->getSymbol()->isPendingPush())
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      nullBlockCursor = nullBlockCursor->getNextTreeTop();
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   if (nullBlockCursor->getNode()->getOpCodeValue() != TR::ResolveAndNULLCHK
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       || nullBlockCursor->getNode()->getFirstChild()->getOpCodeValue() != TR::call
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       || nullBlockCursor->getNode()->getFirstChild()->getFirstChild() != exceptionNode)
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      return false;
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   TR::Node *initCall = nullBlockCursor->getNode()->getFirstChild();
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   if (trace())
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      traceMsg(comp(), "   Matched call node %d\n", initCall->getGlobalIndex());
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   if (!initCall->getSymbolReference()->isUnresolved())
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      return false;
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   TR::Method *calleeMethod = initCall->getSymbol()->castToMethodSymbol()->getMethod();
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   if (trace())
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      traceMsg(comp(), "   Matched calleeMethod %s %s %s\n", calleeMethod->classNameChars(), calleeMethod->nameChars(), calleeMethod->signatureChars());
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   if (strncmp(calleeMethod->nameChars(), "<init>", 6) != 0
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       || strncmp(calleeMethod->classNameChars(), "java/lang/NullPointerException", 30) != 0
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       || strncmp(calleeMethod->signatureChars(), "()V", 3) != 0)
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      return false;
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   if (trace())
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      traceMsg(comp(), "   Matched NPE init\n");
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   nullBlockCursor = nullBlockCursor->getNextTreeTop();
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   if ((nullBlockCursor->getNode()->getOpCodeValue() != TR::NULLCHK
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        && nullBlockCursor->getNode()->getOpCodeValue() != TR::treetop)
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       || nullBlockCursor->getNode()->getFirstChild()->getOpCodeValue() != TR::athrow
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       || nullBlockCursor->getNode()->getFirstChild()->getFirstChild() != exceptionNode)
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      return false;
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   if (trace())
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      traceMsg(comp(), "   Matched throw\n");
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   TR::Node *throwNode = nullBlockCursor->getNode()->getFirstChild();
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   nullBlockCursor = nullBlockCursor->getNextTreeTop();
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   if (nullBlockCursor != nullBlock->getExit())
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      return false;
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   if (!performTransformation(comp(), "%sReplace ifacmpeq/ifacmpne of NULL node [%p] to throw of an NPE exception with NULLCHK\n", OPT_DETAILS, compareNode))
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      return false;
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   _cfg->invalidateStructure();
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   TR::DebugCounter::incStaticDebugCounter(comp(), TR::DebugCounter::debugCounterName(comp(), "cfgSimpNULLCHK/unresolvedNonNull/(%s)", comp()->signature()));
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   TR::Block *checkBlock = _block;
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   if (hasExceptionPoint(_block, compareTreeTop))
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      checkBlock = _block->split(compareTreeTop, _cfg, true, false);
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   if (!nullBlock->getExceptionSuccessors().empty())
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      {
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      for (auto itr = nullBlock->getExceptionSuccessors().begin(), end = nullBlock->getExceptionSuccessors().end(); itr != end; ++itr)
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         {
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         _cfg->addExceptionEdge(checkBlock, (*itr)->getTo());
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         }
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      }
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   TR::Node *passthroughNode = TR::Node::create(throwNode, TR::PassThrough, 1);
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   passthroughNode->setAndIncChild(0, compareNode->getFirstChild());
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   TR::SymbolReference *symRef = comp()->getSymRefTab()->findOrCreateNullCheckSymbolRef(comp()->getMethodSymbol());
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   TR::Node *nullchkNode = TR::Node::createWithSymRef(TR::NULLCHK, 1, 1, passthroughNode, symRef);
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   if (trace())
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      traceMsg(comp(), "End simplifyUnresolvedRequireNonNull. Generated NULLCHK node n%dn\n", nullchkNode->getGlobalIndex());
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   TR::TreeTop *nullchkTree = TR::TreeTop::create(comp(), nullchkNode);
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   checkBlock->getEntry()->insertAfter(nullchkTree);
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   _cfg->removeEdge(checkBlock, nullBlock);
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   TR::TransformUtil::removeTree(comp(), compareTreeTop);
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   if (checkBlock->getNextBlock() != nonnullBlock)
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      {
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      TR::Node *gotoNode = TR::Node::create(nullchkNode, TR::Goto, 0);
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      gotoNode->setBranchDestination(nonnullBlock->getEntry());
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      checkBlock->append(TR::TreeTop::create(comp(), gotoNode));
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      }
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   return true;
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   }
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// Look for pattern of the form:
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//
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// ifacmpeq block_A
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//   ... some ref
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//   aconst NULL
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//
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// OR
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//
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// ifacmpne block_A
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//   ... some ref
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//   aconst NULL
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//
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// Where block_A looks like:
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// treetop
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//    new
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//       loadaddr java/lang/NullPointerException
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// treetop | NULLCHK
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//    call java/lang/NullPointerException.<init>();
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//       => new
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// treetop | NULLCHK
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//    athrow
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//       => new
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//
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// Replace the branch with a NULLCHK PassThrough of some ref
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//
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bool J9::CFGSimplifier::simplifyResolvedRequireNonNull(bool needToDuplicateTree)
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   {
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   static char *disableSimplifyExplicitNULLTest = feGetEnv("TR_disableSimplifyExplicitNULLTest");
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   static char *disableSimplifyResolvedRequireNonNull = feGetEnv("TR_disableSimplifyResolvedRequireNonNull");
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   if (disableSimplifyExplicitNULLTest != NULL || disableSimplifyResolvedRequireNonNull != NULL)
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      return false;
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   if (comp()->getOSRMode() == TR::involuntaryOSR)
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         return false;
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   if (trace())
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      traceMsg(comp(), "Start simplifyResolvedRequireNonNull\n");
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   // This block must end in an ifacmpeq or ifacmpne against aconst NULL
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   TR::TreeTop *compareTreeTop = getLastRealTreetop(_block);
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   TR::Node *compareNode       = compareTreeTop->getNode();
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   if (compareNode->getOpCodeValue() != TR::ifacmpeq
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       && compareNode->getOpCodeValue() != TR::ifacmpne)
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      return false;
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   if (trace())
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      traceMsg(comp(), "   Found an ifacmp[eq/ne] n%dn\n", compareNode->getGlobalIndex());
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   if (compareNode->getSecondChild()->getOpCodeValue() != TR::aconst
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       || compareNode->getSecondChild()->getAddress() != 0)
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      return false;
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   // _next1 is fall through so grab the block where the value is NULL
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   TR::Block *nullBlock = compareNode->getOpCodeValue() == TR::ifacmpeq ? _next2 : _next1;
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   TR::Block *nonnullBlock = compareNode->getOpCodeValue() == TR::ifacmpeq ? _next1 : _next2;
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   traceMsg(comp(), "   Found nullBlock %d\n", nullBlock->getNumber());
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   TR::TreeTop *nullBlockCursor = nullBlock->getEntry()->getNextTreeTop();
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   if (nullBlockCursor->getNode()->getOpCodeValue() != TR::treetop
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       || nullBlockCursor->getNode()->getFirstChild()->getOpCodeValue() != TR::New
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       || nullBlockCursor->getNode()->getFirstChild()->getFirstChild()->getOpCodeValue() != TR::loadaddr)
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      return false;
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   if (trace())
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      traceMsg(comp(), "   Matched new tree\n");
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   TR::Node *exceptionNode = nullBlockCursor->getNode()->getFirstChild();
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   TR::Node *loadaddr = nullBlockCursor->getNode()->getFirstChild()->getFirstChild();
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   // check for java/lang/NullPointerException as the loadaddr
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   TR_OpaqueClassBlock *NPEclazz = comp()->fej9()->getSystemClassFromClassName("java/lang/NullPointerException", strlen("java/lang/NullPointerException"));
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   if (loadaddr->getSymbolReference()->isUnresolved()
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       || loadaddr->getSymbolReference()->getSymbol()->castToStaticSymbol()->getStaticAddress() != NPEclazz)
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      return false;
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   if (trace())
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      traceMsg(comp(), "   Matched new tree class\n");
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   nullBlockCursor = nullBlockCursor->getNextTreeTop();
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   // optionally match pending push store
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   if (nullBlockCursor->getNode()->getOpCodeValue() == TR::astore
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       && nullBlockCursor->getNode()->getFirstChild() == exceptionNode
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       && nullBlockCursor->getNode()->getSymbol()->isPendingPush())
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      nullBlockCursor = nullBlockCursor->getNextTreeTop();
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   if ((nullBlockCursor->getNode()->getOpCodeValue() != TR::treetop
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        && nullBlockCursor->getNode()->getOpCodeValue() != TR::NULLCHK)
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       || nullBlockCursor->getNode()->getFirstChild()->getOpCodeValue() != TR::call
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       || nullBlockCursor->getNode()->getFirstChild()->getFirstChild() != exceptionNode)
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      return false;
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   if (trace())
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      traceMsg(comp(), "   Matched exceptionNode\n");
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   TR::Node *initCall = nullBlockCursor->getNode()->getFirstChild();
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   if (initCall->getSymbolReference()->isUnresolved())
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      return false;
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   TR_ResolvedMethod *calleeMethod = initCall->getSymbol()->castToResolvedMethodSymbol()->getResolvedMethod();
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   if (trace())
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      traceMsg(comp(), "   Matched calleeMethod %s %s %s\n", calleeMethod->classNameChars(), calleeMethod->nameChars(), calleeMethod->signatureChars());
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   if (strncmp(calleeMethod->nameChars(), "<init>", 6) != 0
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       || strncmp(calleeMethod->classNameChars(), "java/lang/Throwable", 19) != 0
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       || strncmp(calleeMethod->signatureChars(), "()V", 3) != 0)
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      return false;
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   if (trace())
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      traceMsg(comp(), "   Matched exceptionNode call\n");
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   nullBlockCursor = nullBlockCursor->getNextTreeTop();
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   if ((nullBlockCursor->getNode()->getOpCodeValue() != TR::treetop
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        && nullBlockCursor->getNode()->getOpCodeValue() != TR::NULLCHK)
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       || nullBlockCursor->getNode()->getFirstChild()->getOpCodeValue() != TR::athrow
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       || nullBlockCursor->getNode()->getFirstChild()->getFirstChild() != exceptionNode)
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      return false;
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   if (trace())
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      traceMsg(comp(), "   Matched exception throw\n");
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   TR::Node *throwNode = nullBlockCursor->getNode()->getFirstChild();
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   nullBlockCursor = nullBlockCursor->getNextTreeTop();
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   if (nullBlockCursor != nullBlock->getExit())
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      return false;
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   if (!performTransformation(comp(), "%sReplace ifacmpeq/ifacmpne of NULL node [%p] to throw of an NPE exception with NULLCHK\n", OPT_DETAILS, compareNode))
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      return false;
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   _cfg->invalidateStructure();
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   TR::DebugCounter::incStaticDebugCounter(comp(), TR::DebugCounter::debugCounterName(comp(), "cfgSimpNULLCHK/resolvedNonNull/(%s)", comp()->signature()));
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   TR::Block *checkBlock = _block;
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   if (hasExceptionPoint(_block, compareTreeTop))
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      checkBlock = _block->split(compareTreeTop, _cfg, true, false);
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   if (!nullBlock->getExceptionSuccessors().empty())
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      {
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      for (auto itr = nullBlock->getExceptionSuccessors().begin(), end = nullBlock->getExceptionSuccessors().end(); itr != end; ++itr)
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         {
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         _cfg->addExceptionEdge(checkBlock, (*itr)->getTo());
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         }
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      }
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   TR::Node *passthroughNode = TR::Node::create(throwNode, TR::PassThrough, 1);
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   passthroughNode->setAndIncChild(0, compareNode->getFirstChild());
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   TR::SymbolReference *symRef = comp()->getSymRefTab()->findOrCreateNullCheckSymbolRef(comp()->getMethodSymbol());
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   TR::Node *nullchkNode = TR::Node::createWithSymRef(TR::NULLCHK, 1, 1, passthroughNode, symRef);
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   if (trace())
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      traceMsg(comp(), "End simplifyResolvedRequireNonNull. Generated NULLCHK node n%dn\n", nullchkNode->getGlobalIndex());
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   TR::TreeTop *nullchkTree = TR::TreeTop::create(comp(), nullchkNode);
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   checkBlock->getEntry()->insertAfter(nullchkTree);
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   _cfg->removeEdge(checkBlock, nullBlock);
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   TR::TransformUtil::removeTree(comp(), compareTreeTop);
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   if (checkBlock->getNextBlock() != nonnullBlock)
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      {
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      TR::Node *gotoNode = TR::Node::create(nullchkNode, TR::Goto, 0);
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      gotoNode->setBranchDestination(nonnullBlock->getEntry());
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      checkBlock->append(TR::TreeTop::create(comp(), gotoNode));
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      }
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   return true;
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   }
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