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VPHandlers.cpp
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/*******************************************************************************
* Copyright IBM Corp. and others 2000
*
* This program and the accompanying materials are made available under
* the terms of the Eclipse Public License 2.0 which accompanies this
* distribution and is available at https://www.eclipse.org/legal/epl-2.0/
* or the Apache License, Version 2.0 which accompanies this distribution
* and is available at https://www.apache.org/licenses/LICENSE-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License, v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception [1] and GNU General Public
* License, version 2 with the OpenJDK Assembly Exception [2].
*
* [1] https://www.gnu.org/software/classpath/license.html
* [2] https://openjdk.org/legal/assembly-exception.html
*
* SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0 OR GPL-2.0-only WITH OpenJDK-assembly-exception-1.0
*******************************************************************************/
#include <algorithm>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include "codegen/CodeGenerator.hpp"
#include "env/FrontEnd.hpp"
#include "env/KnownObjectTable.hpp"
#include "codegen/RecognizedMethods.hpp"
#include "codegen/InstOpCode.hpp"
#include "compile/Compilation.hpp"
#include "compile/Method.hpp"
#include "compile/ResolvedMethod.hpp"
#include "compile/SymbolReferenceTable.hpp"
#include "compile/VirtualGuard.hpp"
#include "control/Options.hpp"
#include "control/Options_inlines.hpp"
#include "cs2/bitvectr.h"
#include "env/CompilerEnv.hpp"
#include "env/IO.hpp"
#include "env/ObjectModel.hpp"
#include "env/PersistentInfo.hpp"
#include "env/TRMemory.hpp"
#include "env/TypeLayout.hpp"
#include "env/jittypes.h"
#include "env/VMAccessCriticalSection.hpp"
#include "il/AliasSetInterface.hpp"
#include "il/AutomaticSymbol.hpp"
#include "il/Block.hpp"
#include "il/DataTypes.hpp"
#include "il/ILOpCodes.hpp"
#include "il/ILOps.hpp"
#include "il/MethodSymbol.hpp"
#include "il/Node.hpp"
#include "il/Node_inlines.hpp"
#include "il/ResolvedMethodSymbol.hpp"
#include "il/StaticSymbol.hpp"
#include "il/Symbol.hpp"
#include "il/SymbolReference.hpp"
#include "il/TreeTop.hpp"
#include "il/TreeTop_inlines.hpp"
#include "infra/Array.hpp"
#include "infra/Assert.hpp"
#include "infra/Bit.hpp"
#include "infra/Cfg.hpp"
#include "infra/Link.hpp"
#include "infra/List.hpp"
#include "infra/SimpleRegex.hpp"
#include "infra/CfgEdge.hpp"
#include "optimizer/Optimization_inlines.hpp"
#include "optimizer/OptimizationManager.hpp"
#include "optimizer/Optimizations.hpp"
#include "optimizer/Optimizer.hpp"
#include "optimizer/PreExistence.hpp"
#include "optimizer/TransformUtil.hpp"
#include "optimizer/UseDefInfo.hpp"
#include "optimizer/VPConstraint.hpp"
#include "optimizer/ValuePropagation.hpp"
#include "ras/Debug.hpp"
#include "ras/DebugCounter.hpp"
#include "runtime/Runtime.hpp"
#ifdef J9_PROJECT_SPECIFIC
#include "env/CHTable.hpp"
#include "env/PersistentCHTable.hpp"
#include "runtime/RuntimeAssumptions.hpp"
#include "env/VMJ9.h"
#include "optimizer/VPBCDConstraint.hpp"
#endif
#define OPT_DETAILS "O^O VALUE PROPAGATION: "
extern TR::Node *constrainChildren(OMR::ValuePropagation *vp, TR::Node *node);
extern TR::Node *constrainVcall(OMR::ValuePropagation *vp, TR::Node *node);
static void checkForNonNegativeAndOverflowProperties(OMR::ValuePropagation *vp, TR::Node *node, TR::VPConstraint *constraint = NULL)
{
if (!constraint)
{
bool isGlobal;
constraint = vp->getConstraint(node, isGlobal);
}
if (node->getOpCode().isLoad())
{
node->setCannotOverflow(true);
//dumpOptDetails(vp->comp(), "Load node %p cannot overflow\n", node);
}
if (constraint)
{
if (constraint->asIntConst())
{
int32_t low = constraint->asIntConst()->getLowInt();
if (low >= 0)
node->setIsNonNegative(true);
if (low <= 0)
node->setIsNonPositive(true);
}
if (constraint->asLongConst())
{
int64_t low = constraint->asLongConst()->getLowLong();
if (low >= 0)
node->setIsNonNegative(true);
if (low <= 0)
node->setIsNonPositive(true);
}
if (constraint->asShortConst())
{
int16_t low = constraint->asShortConst()->getLowShort();
if (low >= 0)
node->setIsNonNegative(true);
if (low <= 0)
node->setIsNonPositive(true);
}
if (constraint->asIntRange())
{
TR::VPIntRange *range = constraint->asIntRange();
int32_t low = range->getLowInt();
if (low >= 0)
node->setIsNonNegative(true);
int32_t high = range->getHighInt();
if (high <= 0)
node->setIsNonPositive(true);
///if ((node->getOpCode().isArithmetic() || node->getOpCode().isLoad()) &&
/// ((low > TR::getMinSigned<TR::Int32>()) || (high < TR::getMaxSigned<TR::Int32>())))
if ((node->getOpCode().isLoad() &&
((low > TR::getMinSigned<TR::Int32>()) || (high < TR::getMaxSigned<TR::Int32>()))) ||
(node->getOpCode().isArithmetic() &&
(range->canOverflow() != TR_yes)))
{
node->setCannotOverflow(true);
//dumpOptDetails(vp->comp(), "Node %p cannot overflow\n", node);
}
}
else if (constraint->asLongRange())
{
TR::VPLongRange *range = constraint->asLongRange();
int64_t low = range->getLowLong();
if (low >= 0)
node->setIsNonNegative(true);
int64_t high = range->getHighLong();
if (high <= 0)
node->setIsNonPositive(true);
///if ((node->getOpCode().isArithmetic() || node->getOpCode().isLoad()) &&
/// ((low > TR::getMinSigned<TR::Int64>()) || (high < TR::getMaxSigned<TR::Int64>())))
if ((node->getOpCode().isLoad() &&
((low > TR::getMinSigned<TR::Int64>()) || (high < TR::getMaxSigned<TR::Int64>()))) ||
(node->getOpCode().isArithmetic() &&
(range->canOverflow() != TR_yes)))
{
node->setCannotOverflow(true);
//dumpOptDetails(vp->comp(), "Node %p cannot overflow\n", node);
}
}
else if (constraint->asShortRange())
{
TR::VPShortRange *range = constraint->asShortRange();
int16_t low = range->getLowShort();
if (low >= 0)
node->setIsNonNegative(true);
int16_t high = range->getHighShort();
if (high <= 0)
node->setIsNonPositive(true);
if ((node->getOpCode().isLoad() && ((low > TR::getMinSigned<TR::Int16>()) || (high < TR::getMaxSigned<TR::Int16>()))) ||
(node->getOpCode().isArithmetic() && (range->canOverflow() != TR_yes)))
{
node->setCannotOverflow(true);
}
}
}
}
static bool isBoolean(TR::VPConstraint *constraint)
{
if (constraint)
{
if (constraint->asIntConst())
{
int32_t low = constraint->asIntConst()->getLowInt();
if ((low >= 0) && (low <= 1))
return true;
}
if (constraint->asLongConst())
{
int64_t low = constraint->asLongConst()->getLowLong();
if ((low >= 0) && (low <= 1))
return true;
}
if (constraint->asShortConst())
{
int16_t low = constraint->asShortConst()->getLowShort();
if ((low >= 0) && (low <= 1))
return true;
}
if (constraint->asIntRange())
{
TR::VPIntRange *range = constraint->asIntRange();
int32_t low = range->getLowInt();
int32_t high = range->getHighInt();
if ((low >= 0) && (high <= 1))
return true;
}
else if (constraint->asLongRange())
{
TR::VPLongRange *range = constraint->asLongRange();
int64_t low = range->getLowLong();
int64_t high = range->getHighLong();
if ((low >= 0) && (high <= 1))
return true;
}
else if (constraint->asShortRange())
{
TR::VPShortRange *range = constraint->asShortRange();
int16_t low = range->getLowShort();
int16_t high = range->getHighShort();
if ((low >= 0) && (high <= 1))
return true;
}
}
return false;
}
static int32_t arrayElementSize(const char *signature, int32_t len, TR::Node *node, OMR::ValuePropagation *vp)
{
if (signature[0] != '[')
return 0;
// regular array element size
if (signature[0] == '[')
{
switch (signature[1])
{
case 'B': return 1;
case 'C':
case 'S': return 2;
case 'I':
case 'F': return 4;
case 'D':
case 'J': return 8;
case 'Z': return static_cast<int32_t>(TR::Compiler->om.elementSizeOfBooleanArray());
case 'L':
default :
return TR::Compiler->om.sizeofReferenceField();
}
}
return 0;
}
// When node is successfully folded, isGlobal is set to true iff all
// constraints in the chain were global, and false otherwise.
static bool tryFoldCompileTimeLoad(
OMR::ValuePropagation *vp,
TR::Node *node,
bool &isGlobal)
{
isGlobal = true;
if (!node->getOpCode().isLoad())
return false;
else if (node->getOpCode().isLoadReg())
return false;
else if (node->getSymbolReference()->isUnresolved())
return false;
if (node->getOpCode().isIndirect())
{
if (vp->trace())
traceMsg(vp->comp(), " constrainCompileTimeLoad inspecting %s %p\n", node->getOpCode().getName(), node);
TR::KnownObjectTable *knot = vp->comp()->getKnownObjectTable();
TR::Node *baseExpression = NULL;
TR::KnownObjectTable::Index baseKnownObject = TR::KnownObjectTable::UNKNOWN;
TR::Node *curNode = node;
for (; !baseExpression; )
{
// Track last curNode because its symref might be improved to ImmutableArrayShadow
TR::Node* prevNode = curNode;
// Look pass aladd/aiadd to get the array object for array shadows
if (curNode->getSymbol()->isArrayShadowSymbol()
&& curNode->getFirstChild()->getOpCode().isArrayRef()
&& curNode->getFirstChild()->getSecondChild()->getOpCode().isLoadConst())
{
curNode = curNode->getFirstChild()->getFirstChild();
}
else curNode = curNode->getFirstChild();
bool curIsGlobal;
TR::VPConstraint *constraint = vp->getConstraint(curNode, curIsGlobal);
if (!curIsGlobal)
isGlobal = false;
if (!constraint)
{
if (vp->trace())
traceMsg(vp->comp(), " - FAIL: %s %p has no constraint\n", curNode->getOpCode().getName(), curNode);
break;
}
else if (curNode->getOpCode().hasSymbolReference() && curNode->getSymbolReference()->isUnresolved())
{
if (vp->trace())
traceMsg(vp->comp(), " - FAIL: %s %p is unresolved\n", curNode->getOpCode().getName(), curNode);
break;
}
else if (constraint->getKnownObject())
{
TR::Symbol* prevNodeSym = prevNode->getSymbol();
// Improve regular array shadows from arrays with immutable content
if (prevNodeSym->isArrayShadowSymbol() &&
// UnsafeShadow responds true to above question, but the type of the array element might not match the type of the symbol,
// it needs to be derived from the array
!prevNodeSym->isUnsafeShadowSymbol() &&
!vp->comp()->getSymRefTab()->isImmutableArrayShadow(prevNode->getSymbolReference()))
{
if (constraint->getKnownObject()->isArrayWithConstantElements(vp->comp()))
{
// Use the DataType of the symbol because it represents the element type of the array
TR::SymbolReference* improvedSymRef = vp->comp()->getSymRefTab()->findOrCreateImmutableArrayShadowSymbolRef(prevNodeSym->getDataType());
if (vp->trace())
traceMsg(vp->comp(), "Found arrayShadow load %p from array with constant elements %p\n", prevNode, curNode);
if (performTransformation(vp->comp(), "%sUsing ImmutableArrayShadow symref #%d for node %p\n", OPT_DETAILS, improvedSymRef->getReferenceNumber(), prevNode))
prevNode->setSymbolReference(improvedSymRef);
// Alias info of calls are computed in createAliasInfo, which is only called if alias info is not available or is invalid.
// Invalidate alias info so that it can be recomputed in the next optimization that needs it
vp->optimizer()->setAliasSetsAreValid(false);
}
else if (!constraint->getKnownObject()->isArrayWithStableElements(vp->comp()))
break;
}
baseExpression = curNode;
baseKnownObject = constraint->getKnownObject()->getIndex();
if (vp->trace())
traceMsg(vp->comp(), " - %s %p is obj%d\n", baseExpression->getOpCode().getName(), baseExpression, baseKnownObject);
break;
}
else if (knot && constraint->isConstString())
{
baseExpression = curNode;
baseKnownObject = knot->getOrCreateIndexAt((uintptr_t*)constraint->getConstString()->getSymRef()->getSymbol()->castToStaticSymbol()->getStaticAddress());
if (vp->trace())
traceMsg(vp->comp(), " - %s %p is string obj%d\n", baseExpression->getOpCode().getName(), baseExpression, baseKnownObject);
break;
}
else if (constraint->isJ9ClassObject() == TR_yes
&& constraint->isNonNullObject()
&& constraint->getClassType()
&& constraint->getClassType()->asFixedClass()
&& constraint->getClass())
{
if (vp->trace())
traceMsg(vp->comp(), " - %s %p is class object - transforming\n", curNode->getOpCode().getName(), curNode);
TR::Node *nodeToRemove = NULL;
uintptr_t clazz = (uintptr_t)constraint->getClass();
bool didSomething = TR::TransformUtil::transformIndirectLoadChainAt(vp->comp(), node, curNode, &clazz, &nodeToRemove);
if (nodeToRemove)
{
TR_ASSERT(didSomething, "How can there be a node to remove if transformIndirectLoadChain didn't do something??");
vp->removeNode(nodeToRemove, true);
return true;
}
return didSomething;
}
else if (node->getSymbolReference() == vp->comp()->getSymRefTab()->findVftSymbolRef()
&& node->getFirstChild() == curNode
&& constraint->isNonNullObject()
&& constraint->getClassType()
&& constraint->getClassType()->asFixedClass()
&& constraint->getClass())
{
TR_OpaqueClassBlock *clazz = constraint->getClass();
#ifdef J9_PROJECT_SPECIFIC
TR_J9VMBase *fej9 = vp->comp()->fej9();
// Non SVM AOT can deal with transformed loadaddr of system class only while Symbol Validation Manager can handle any class.
// Skip the transformation under non SVM AOT when class is not loaded by bootstrap class loader.
// TODO: Disabling tranformation on Power for non SVM AOT because it does not add external relocation record. Enable this once it is fixed.
if (vp->comp()->compileRelocatableCode() && !vp->comp()->getOption(TR_UseSymbolValidationManager) && (vp->comp()->target().cpu.isPower() || fej9->getClassLoader(clazz) != fej9->getSystemClassLoader()))
return false;
#endif
// performTransformation() is needed here but not in the other cases
// because transformIndirectLoadChain[At]() does one internally.
if (!performTransformation(
vp->comp(),
"%sTransforming VFT load n%un [%p] to loadaddr "
"based on the fixed type of n%un [%p]\n",
OPT_DETAILS,
node->getGlobalIndex(),
node,
curNode->getGlobalIndex(),
curNode))
return false;
node->setNumChildren(0);
TR::Node::recreateWithSymRef(node, TR::loadaddr, vp->comp()->getSymRefTab()->findOrCreateClassSymbol(vp->comp()->getMethodSymbol(), -1, clazz));
node->setFlags(0);
vp->removeNode(curNode, true);
TR::DebugCounter::incStaticDebugCounter(vp->comp(), TR::DebugCounter::debugCounterName(vp->comp(), "VFTLoadKnownObject/(%s)/%s", vp->comp()->signature(), vp->comp()->getHotnessName(vp->comp()->getMethodHotness())));
return true;
}
else if (!curNode->getOpCode().isLoadIndirect())
{
if (curNode->getOpCodeValue() == TR::loadaddr
&& curNode->getSymbolReference()->getSymbol()->isClassObject()
&& !curNode->getSymbolReference()->isUnresolved())
{
TR::Node *nodeToRemove = NULL;
uintptr_t clazz = (uintptr_t)curNode->getSymbolReference()->getSymbol()->getStaticSymbol()->getStaticAddress();
bool didSomething = TR::TransformUtil::transformIndirectLoadChainAt(vp->comp(), node, curNode, &clazz, &nodeToRemove);
if (nodeToRemove)
{
TR_ASSERT(didSomething, "How can there be a node to remove if transformIndirectLoadChain didn't do something??");
vp->removeNode(nodeToRemove, true);
return true;
}
return didSomething;
}
else
{
if (vp->trace())
traceMsg(vp->comp(), " - FAIL: %s %p is not an indirect load and has insufficient constraints\n", curNode->getOpCode().getName(), curNode);
break;
}
}
#ifdef J9_PROJECT_SPECIFIC
else if (vp->comp()->fej9()->isFinalFieldPointingAtJ9Class(curNode->getSymbolReference(), vp->comp()))
{
if (vp->trace())
traceMsg(vp->comp(), " - FAIL: %s %p points to a j9class but has insufficient constraints\n", curNode->getOpCode().getName(), curNode);
baseExpression = NULL;
break;
}
else if (vp->comp()->fej9()->canDereferenceAtCompileTime(curNode->getSymbolReference(), vp->comp()))
{
// we can continue up the dereference chain
if (vp->trace())
traceMsg(vp->comp(), " - %s %p is %s\n", curNode->getOpCode().getName(), curNode, curNode->getSymbolReference()->getName(vp->comp()->getDebug()));
continue;
}
#endif
else
{
if (vp->trace())
traceMsg(vp->comp(), " - FAIL: %s %p is %s\n", curNode->getOpCode().getName(), curNode, curNode->getSymbolReference()->getName(vp->comp()->getDebug()));
break;
}
}
if (baseExpression)
{
// We've got something we can ask the front end to transform
//
TR::Node *nodeToRemove = NULL;
bool didSomething = TR::TransformUtil::transformIndirectLoadChain(vp->comp(), node, baseExpression, baseKnownObject, &nodeToRemove);
if (nodeToRemove)
{
TR_ASSERT(didSomething, "How can there be a node to remove if transformIndirectLoadChain didn't do something??");
vp->removeNode(nodeToRemove, true);
}
return didSomething;
}
else
{
return false;
}
}
else
{
// Do direct loads too
return false;
}
TR_ASSERT(0, "Shouldn't get here");
return true; // Safe default
}
static bool constrainCompileTimeLoad(OMR::ValuePropagation *vp, TR::Node *node)
{
bool isGlobal;
if (!tryFoldCompileTimeLoad(vp, node, isGlobal))
return false;
// Add a constraint so that VP can continue with the constant value.
constrainNewlyFoldedConst(vp, node, isGlobal);
return true;
}
static bool findConstant(OMR::ValuePropagation *vp, TR::Node *node)
{
// See if the node is already known to be a constant
//
bool isGlobal;
TR::VPConstraint *constraint = vp->getConstraint(node, isGlobal);
if (constraint)
{
TR::DataType type = node->getDataType();
switch (type)
{
case TR::Int64:
case TR::Double:
if (constraint->asLongConst())
{
bool replacedConst = false;
if (!vp->cg()->materializesLargeConstants() ||
(!node->getType().isInt64()) ||
(constraint->asLongConst()->getLong() < vp->cg()->getSmallestPosConstThatMustBeMaterialized() &&
constraint->asLongConst()->getLong() > vp->cg()->getLargestNegConstThatMustBeMaterialized()) ||
(vp->getCurrentParent()->getOpCode().isMul() &&
(vp->getCurrentParent()->getSecondChild() == node) &&
isNonNegativePowerOf2(constraint->asLongConst()->getLong())))
{
vp->replaceByConstant(node, constraint, isGlobal);
replacedConst = true;
}
if (constraint->getLowLong())
node->setIsNonZero(true);
else
node->setIsZero(true);
return replacedConst;
}
break;
case TR::Address:
if (constraint->isNullObject())
{
vp->replaceByConstant(node, constraint, isGlobal);
node->setIsNull(true);
return true;
}
else if (constraint->isNonNullObject())
{
node->setIsNonNull(true);
if (constraint->getKnownObject())
{
TR::VPKnownObject *knownObject = constraint->getKnownObject();
// Don't do direct loads here till we get the aliasing right
if (node->getOpCode().isLoadIndirect() && !node->getSymbolReference()->hasKnownObjectIndex())
{
TR::KnownObjectTable *knot = vp->comp()->getKnownObjectTable();
TR_ASSERT(knot, "Can't have a known-object constraint without a known-object table");
TR::SymbolReference *improvedSymRef = vp->comp()->getSymRefTab()->findOrCreateSymRefWithKnownObject(node->getSymbolReference(), knownObject->getIndex());
if (improvedSymRef->hasKnownObjectIndex())
{
if (performTransformation(vp->comp(), "%sUsing known-object specific symref #%d for obj%d at [%p]\n", OPT_DETAILS, improvedSymRef->getReferenceNumber(), knownObject->getIndex(), node))
{
node->setSymbolReference(improvedSymRef);
return true;
}
}
}
else if (node->getOpCode().isLoadDirect() &&
!node->hasKnownObjectIndex() &&
!node->getSymbolReference()->hasKnownObjectIndex() &&
node->getSymbolReference()->getSymbol()->isAutoOrParm())
{
if (performTransformation(vp->comp(), "%sSetting known-object obj%d on node [%p]\n", OPT_DETAILS, knownObject->getIndex(), node))
node->setKnownObjectIndex(knownObject->getIndex());
}
}
}
break;
default:
if (constraint->asIntConstraint())
{
int32_t value = constraint->getLowInt();
if (constraint->asIntConst())
{
bool replacedConst = false;
if (!vp->cg()->materializesLargeConstants() ||
(!node->getType().isInt32()) ||
(value < vp->cg()->getSmallestPosConstThatMustBeMaterialized() &&
value > vp->cg()->getLargestNegConstThatMustBeMaterialized()) ||
(vp->getCurrentParent()->getOpCode().isMul() &&
(vp->getCurrentParent()->getSecondChild() == node) &&
isNonNegativePowerOf2(value))
)
{
vp->replaceByConstant(node, constraint, isGlobal);
replacedConst = true;
}
if (value)
node->setIsNonZero(true);
else
node->setIsZero(true);
return replacedConst;
}
else if (value >= 0)
node->setIsNonNegative(true);
if (constraint->getHighInt() <= 0)
node->setIsNonPositive(true);
if ((node->getOpCode().isArithmetic() || node->getOpCode().isLoad()) &&
((value > TR::getMinSigned<TR::Int32>()) || (constraint->getHighInt() < TR::getMaxSigned<TR::Int32>())))
{
node->setCannotOverflow(true);
}
}
else if (constraint->asShortConstraint())
{
int16_t value = constraint->getLowShort();
if (constraint->asShortConst())
{
bool replacedConst = false;
if (!vp->cg()->materializesLargeConstants() ||
(!node->getType().isInt16()) ||
(value < vp->cg()->getSmallestPosConstThatMustBeMaterialized() &&
value > vp->cg()->getLargestNegConstThatMustBeMaterialized()) ||
(vp->getCurrentParent()->getOpCode().isMul() &&
vp->getCurrentParent()->getSecondChild() == node &&
isNonNegativePowerOf2(value)))
{
vp->replaceByConstant(node,constraint,isGlobal);
replacedConst = true;
}
if (value)
node->setIsNonZero(true);
else
node->setIsZero(true);
return replacedConst;
}
else if (value >= 0)
node->setIsNonNegative(true);
if (constraint->getHighShort() <= 0)
node->setIsNonPositive(true);
if ((node->getOpCode().isArithmetic() || node->getOpCode().isLoad()) &&
((value > TR::getMinSigned<TR::Int16>()) || (constraint->getHighShort() < TR::getMaxSigned<TR::Int16>())))
{
node->setCannotOverflow(true);
}
}
break;
}
}
return false;
}
static bool refuseToConstrainUnsafe(
OMR::ValuePropagation *vp, TR::Node *node, const char *why)
{
if (vp->trace())
{
traceMsg(
vp->comp(),
"Refusing to constrain unsafe access n%un [%p]: %s\n",
node->getGlobalIndex(),
node,
why);
}
return true;
}
// Returns true to tell the handler to leave node unconstrained, or false to
// allow it to keep constraining. When the result is false, node may have been
// mutated.
static bool refineUnsafeAccess(OMR::ValuePropagation *vp, TR::Node *node)
{
const bool okToConstrainNormally = false;
TR::Compilation *comp = vp->comp();
TR::SymbolReference *symRef = node->getSymbolReference();
if (symRef->isLitPoolReference())
return refuseToConstrainUnsafe(vp, node, "literal pool reference");
TR::Symbol *sym = symRef->getSymbol();
if (!sym->isShadow())
return okToConstrainNormally;
if (symRef == vp->getSymRefTab()->findInstanceShapeSymbolRef()
|| symRef == vp->getSymRefTab()->findInstanceDescriptionSymbolRef()
|| symRef == vp->getSymRefTab()->findDescriptionWordFromPtrSymbolRef()
#ifdef J9_PROJECT_SPECIFIC
|| symRef == vp->getSymRefTab()->findClassFromJavaLangClassAsPrimitiveSymbolRef()
#endif
|| sym == comp->getSymRefTab()->findGenericIntShadowSymbol())
{
return refuseToConstrainUnsafe(vp, node, "special symref other than unsafe shadow");
}
if (!sym->isUnsafeShadowSymbol())
return okToConstrainNormally;
static const bool disable =
feGetEnv("TR_disableUnsafeShadowRefinement") != NULL;
if (disable)
return refuseToConstrainUnsafe(vp, node, "unsafe shadow refinement is disabled");
if (vp->trace())
{
traceMsg(
comp,
"Found unsafe shadow access n%un [%p]\n",
node->getGlobalIndex(),
node);
}
if (comp->compileRelocatableCode()
&& !comp->getOption(TR_UseSymbolValidationManager))
{
return refuseToConstrainUnsafe(vp, node, "AOT without SVM");
}
if (symRef->getOffset() != 0)
return refuseToConstrainUnsafe(vp, node, "shadow symref has nonzero offset");
TR::Node *addr = node->getChild(0);
TR::ILOpCodes addrOp = addr->getOpCodeValue();
if (addrOp != TR::aladd && addrOp != TR::aiadd)
return refuseToConstrainUnsafe(vp, node, "address not from an offset op");
TR::Node *obj = addr->getChild(0);
bool objIsGlobal = false;
TR::VPConstraint *objConstraint = vp->getConstraint(obj, objIsGlobal);
if (objConstraint == NULL)
return refuseToConstrainUnsafe(vp, node, "unconstrained base object");
TR_OpaqueClassBlock *objClass = NULL;
if (objConstraint->isClassObject() != TR_yes)
{
objClass = objConstraint->getClass();
}
else
{
// objConstraint->getClass() is a bound on the *represented* class. If
// the base happens to be a known object, try to get its type that way.
TR::VPKnownObject *knownObj = objConstraint->getKnownObject();
if (knownObj != NULL)
{
TR::VMAccessCriticalSection getClassCriticalSection(
comp,
TR::VMAccessCriticalSection::tryToAcquireVMAccess);
if (getClassCriticalSection.hasVMAccess())
{
TR::KnownObjectTable *knot = comp->getKnownObjectTable();
TR::KnownObjectTable::Index koi = knownObj->getIndex();
objClass = TR::Compiler->cls.objectClass(comp, knot->getPointer(koi));
}
else if (vp->trace())
{
traceMsg(comp, "Failed to get VM access\n");
}
}
}
if (objClass == NULL)
return refuseToConstrainUnsafe(vp, node, "unknown-type base object");
int32_t objClassSigLen = 0;
const char *objClassSig =
TR::VPResolvedClass::create(vp, objClass)->getClassSignature(objClassSigLen);
if (vp->trace())
{
traceMsg(
comp,
"Base object type is %p %.*s\n",
objClass,
objClassSigLen,
objClassSig);
}
TR::DataTypes nodeType = node->getOpCode().getDataType().getDataType();
TR::SymbolReferenceTable *srTab = comp->getSymRefTab();
if (TR::Compiler->cls.isClassArray(comp, objClass))
{
if (vp->trace())
traceMsg(comp, "Base object is an array\n");
TR::DataTypes elemType = TR::NoType;
if (TR::Compiler->cls.isPrimitiveArray(comp, objClass))
elemType = TR::Compiler->cls.primitiveArrayComponentType(comp, objClass);
else if (TR::Compiler->cls.isReferenceArray(comp, objClass))
elemType = TR::Address;
if (elemType == TR::NoType)
return refuseToConstrainUnsafe(vp, node, "unknown array component type");
if (elemType != nodeType)
{
static const bool dontRefineTypePun =
feGetEnv("TR_dontRefineUnsafeToTypePunnedArrayShadow") != NULL;
if (dontRefineTypePun)
return refuseToConstrainUnsafe(vp, node, "type-punned array access");
}
if (sym->isVolatile())
{
// We don't have a representation for volatile array shadows, and it's
// not straightforward to add one because we'd have to move volatile
// status to SymbolReference from Symbol.
return refuseToConstrainUnsafe(vp, node, "volatile array access");
}
TR::SymbolReference *arrayShadow =
srTab->findOrCreateArrayShadowSymbolRef(elemType, obj);
if (!performTransformation(
comp,
"%sRefine unsafe shadow access n%un [%p] to %s array shadow #%d\n",
OPT_DETAILS,
node->getGlobalIndex(),
node,
TR::DataType::getName(elemType),
arrayShadow->getReferenceNumber()))
return refuseToConstrainUnsafe(vp, node, "performTransformation denied");
node->setSymbolReference(arrayShadow);
return okToConstrainNormally;
}
const TR::TypeLayout *layout = comp->typeLayout(objClass);
if (layout == NULL)
return refuseToConstrainUnsafe(vp, node, "missing type layout");
TR::Node *offset = addr->getChild(1);
if (!offset->getOpCode().isLoadConst())
return refuseToConstrainUnsafe(vp, node, "non-constant offset");
int64_t offsetValueSigned = offset->getConstValue();
if (offsetValueSigned < 0)
return refuseToConstrainUnsafe(vp, node, "negative offset");
uint64_t offsetValue = (uint64_t)offsetValueSigned;
const TR::TypeLayoutEntry *field = NULL;
size_t i = 0;
for (; i < layout->count(); i++)
{
field = &layout->entry(i);
if (field->_offset == offsetValue && field->_datatype.getDataType() == nodeType)
break;
}
if (i >= layout->count())
return refuseToConstrainUnsafe(vp, node, "no matching field");
if (field->_isVolatile != sym->isVolatile())
{
// We don't have a representation for field shadows with the unexpected
// volatility, and it's not straightforward to add one because we'd have
// to move volatile status to SymbolReference from Symbol.
//
// Functionally it would be fine to go on and refine anyway if the field
// is volatile. Doing so would still improve aliasing, but it would make
// the access itself more expensive, so just leave it alone for now.
//
const char *mismatch = field->_isVolatile
? "non-volatile access to volatile field"
: "volatile access to non-volatile field";
return refuseToConstrainUnsafe(vp, node, mismatch);
}
TR::SymbolReference *refinedSymRef = srTab->findOrFabricateShadowSymbol(
objClass,
field->_datatype,
field->_offset,
field->_isVolatile,
field->_isPrivate,
field->_isFinal,
field->_fieldname,
field->_typeSignature);
if (!performTransformation(
comp,
"%sRefine unsafe shadow access n%un [%p] to field shadow #%d %.*s.%s %s\n",
OPT_DETAILS,
node->getGlobalIndex(),
node,
refinedSymRef->getReferenceNumber(),
objClassSigLen,
objClassSig,
field->_fieldname,
field->_typeSignature))
return refuseToConstrainUnsafe(vp, node, "performTransformation denied");
node->setSymbolReference(refinedSymRef);
node->setAndIncChild(0, obj);
addr->recursivelyDecReferenceCount();
return okToConstrainNormally;
}
static bool owningMethodDoesNotContainNullChecks(OMR::ValuePropagation *vp, TR::Node *node)
{
TR::ResolvedMethodSymbol *method = node->getSymbolReference()->getOwningMethodSymbol(vp->comp());
if (method && method->skipNullChecks())
return true;
return false;
}
bool constraintFitsInIntegerRange(OMR::ValuePropagation *vp, TR::VPConstraint *constraint)
{
if (constraint == NULL)
return false;
TR::VPLongConstraint *longConstraint = constraint->asLongConstraint();
TR::VPIntConstraint *intConstraint = constraint->asIntConstraint();
TR::VPShortConstraint *shortConstraint = constraint->asShortConstraint();
if (longConstraint)
{
int64_t low = longConstraint->getLowLong(), high = longConstraint->getHighLong();
if (low >= TR::getMinSigned<TR::Int32>() && high <= TR::getMaxSigned<TR::Int32>())
return true;
}
else if (intConstraint || shortConstraint)
return true;
return false;
}
bool canMoveLongOpChildDirectly(TR::Node *node, int32_t numChild, TR::Node *arithNode)
{
return node->getChild(numChild)->getDataType() == arithNode->getDataType() || (node->getOpCodeValue() == TR::lshr && numChild > 0);
}
bool reduceLongOpToIntegerOp(OMR::ValuePropagation *vp, TR::Node *node, TR::VPConstraint *nodeConstraint)
{
if (!constraintFitsInIntegerRange(vp, nodeConstraint))
return false;
for (int32_t i = 0; i < node->getNumChildren(); i++)
{
bool isGlobal;
TR::VPConstraint *childConstraint = vp->getConstraint(node->getChild(i), isGlobal);
if (!constraintFitsInIntegerRange(vp, childConstraint))
return false;
}
// Adding this check because it is likely suboptimal on machines where you can use long registers to convert things to integers and insert conversion trees.
// Conversion trees are not free.
// LoadExtensions (and other codegen peepholes) should in theory catch uneeded conversions (like widening) as described in the case below on 64 bit platforms.
if (vp->comp()->target().is64Bit() || vp->comp()->cg()->use64BitRegsOn32Bit())
return false;
// The node and all children have constraints that fit in integer range.
// lrem becomes i2l
// i2l irem (new node)
// iload iload (get rid of the l2i)
// lconst l2i (new node)
// lconst
TR::ILOpCodes newOp = TR::ILOpCode::integerOpForLongOp(node->getOpCodeValue());
if (newOp == TR::BadILOp)
return false;
if (performTransformation(vp->comp(), "%sReduce %s (0x%p) to integer arithmetic\n",
OPT_DETAILS, node->getOpCode().getName(), node))
{
TR::Node *arithNode = TR::Node::create(node, newOp, node->getNumChildren());
for (int32_t i = 0; i < node->getNumChildren(); i++)
{
TR::Node *child = node->getChild(i);
if (canMoveLongOpChildDirectly(node, i, arithNode))
{
arithNode->setAndIncChild(i, child);
dumpOptDetails(vp->comp(), " Transfer integer child %d %s (0x%p)\n", i, child->getOpCode().getName(), child);