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ExpressionsSimplification.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 "optimizer/ExpressionsSimplification.hpp"
#include <stddef.h>
#include <stdint.h>
#include "compile/Compilation.hpp"
#include "env/StackMemoryRegion.hpp"
#include "env/TRMemory.hpp"
#include "env/jittypes.h"
#include "il/AliasSetInterface.hpp"
#include "il/Block.hpp"
#include "il/ILOpCodes.hpp"
#include "il/ILOps.hpp"
#include "il/Node.hpp"
#include "il/Node_inlines.hpp"
#include "il/Symbol.hpp"
#include "il/SymbolReference.hpp"
#include "il/TreeTop.hpp"
#include "il/TreeTop_inlines.hpp"
#include "infra/Assert.hpp"
#include "infra/BitVector.hpp"
#include "infra/Cfg.hpp"
#include "infra/List.hpp"
#include "infra/CfgEdge.hpp"
#include "infra/CfgNode.hpp"
#include "optimizer/Dominators.hpp"
#include "optimizer/LocalAnalysis.hpp"
#include "optimizer/Optimization.hpp"
#include "optimizer/Optimization_inlines.hpp"
#include "optimizer/Structure.hpp"
#include "optimizer/TransformUtil.hpp"
#include "optimizer/VPConstraint.hpp"
#include "ras/Debug.hpp"
#define OPT_DETAILS "O^O EXPRESSION SIMPLIFICATION: "
TR_ExpressionsSimplification::TR_ExpressionsSimplification(TR::OptimizationManager *manager)
: TR::Optimization(manager)
{}
int32_t
TR_ExpressionsSimplification::perform()
{
TR::StackMemoryRegion stackMemoryRegion(*trMemory());
int32_t cost = 0;
_supportedExpressions = NULL;
if (trace())
{
comp()->dumpMethodTrees("Trees Before Performing Expression Simplification");
}
cost = perform(comp()->getFlowGraph()->getStructure());
return cost;
}
// Process the structure recursively
//
int32_t
TR_ExpressionsSimplification::perform(TR_Structure * str)
{
if (trace())
traceMsg(comp(), "Analyzing root Structure : %p\n", str);
TR_RegionStructure *region;
// Only regions can be simplified
//
if (!(region = str->asRegion()))
return 0;
TR_RegionStructure::Cursor it(*region);
for (TR_StructureSubGraphNode *node = it.getCurrent();
node != 0;
node = it.getNext())
{
// Too strict
/*
if ((node->getPredecessors().size() == 1))
{
TR::CFGEdge *edge = node->getPredecessors().front();
TR_StructureSubGraphNode *pred = toStructureSubGraphNode(edge->getFrom());
TR_BlockStructure *b = pred->getStructure()->asBlock();
if (b && pred->getSuccessors().size() == 1))
perform(node->getStructure());
}
*/
perform(node->getStructure());
}
// debug only
//
/*
if (region->isNaturalLoop() &&
(region->getParent() &&
!region->getParent()->asRegion()->isCanonicalizedLoop()))
{
traceMsg(comp(), "Loop not canonicalized %x\n", region);
}
*/
TR::Block *entryBlock = region->getEntryBlock();
if (region->isNaturalLoop() && !entryBlock->isCold() &&
(region->getParent() /* &&
region->getParent()->asRegion()->isCanonicalizedLoop() */))
{
if (trace())
traceMsg(comp(), "Found candidate non cold loop %p for expression elimination\n", region);
findAndSimplifyInvariantLoopExpressions(region);
}
return 1; // Need to specify the cost
}
void
TR_ExpressionsSimplification::findAndSimplifyInvariantLoopExpressions(TR_RegionStructure * region)
{
_currentRegion = region;
TR::Block *entryBlock = _currentRegion->getEntryBlock();
if (trace())
traceMsg(comp(), "Entry block: %p in loop region %p\n", entryBlock, region);
// Generate a list of blocks that can be processed
// Criteria: the block must be excucted exactly once
//
TR_ScratchList<TR::Block> candidateBlocksList(trMemory());
_currentRegion->getBlocks(&candidateBlocksList);
if (candidateBlocksList.getSize() > 1)
{
if (trace())
traceMsg(comp(), "More than 1 blocks in the natural loop, need to remove uncertain blocks\n");
removeUncertainBlocks(_currentRegion, &candidateBlocksList);
if (candidateBlocksList.getSize() < 1)
return;
}
_currentRegion->resetInvariance();
_currentRegion->computeInvariantExpressions();
// The rest is the transformation
//
// For each block that is definitely executed once
// analyze its nodes
//
ListIterator<TR::Block> candidateBlocks;
candidateBlocks.set(&candidateBlocksList);
simplifyInvariantLoopExpressions(candidateBlocks);
}
void TR_ExpressionsSimplification::simplifyInvariantLoopExpressions(ListIterator<TR::Block> &blocks)
{
// Need to locate the induction variable of the loop
//
LoopInfo *loopInfo = findLoopInfo(_currentRegion);
bool canReduceSummations = false;
if (!loopInfo)
{
if (trace())
traceMsg(comp(), "Accurate loop info is not found, cannot carry out summation reduction\n");
}
else
{
if (trace())
traceMsg(comp(), "Accurate loop info has been found, will try to carry out summation reduction\n");
int32_t iters = loopInfo->getNumIterations();
if (loopInfo->getBoundaryNode())
{
if (trace())
traceMsg(comp(), "Variable iterations from node %p has not been handled\n",loopInfo->getBoundaryNode());
}
else if (iters <= 0)
{
if (trace())
traceMsg(comp(), "Failed to determine iteration count\n");
}
else
{
canReduceSummations = true;
if (trace())
traceMsg(comp(), "Natural Loop %p will run %d times\n", _currentRegion, iters);
}
}
// Initialize the list of candidates
//
_candidates = new (trStackMemory()) TR_ScratchList<SimplificationCandidateTuple>(trMemory());
for (TR::Block *currentBlock = blocks.getFirst(); currentBlock; currentBlock = blocks.getNext())
{
if (trace())
traceMsg(comp(), "Analyzing block #%d, which must be executed once per iteration\n", currentBlock->getNumber());
// Scan through each node in the block
//
TR::TreeTop *tt = currentBlock->getEntry();
TR::TreeTop *exitTreeTop = currentBlock->getExit();
while (tt != exitTreeTop)
{
TR::Node *currentNode = tt->getNode();
if (trace())
traceMsg(comp(), "Analyzing tree top node %p\n", currentNode);
if (canReduceSummations)
{
// requires loop info for the number of iterations
setSummationReductionCandidates(currentNode, tt);
}
setStoreMotionCandidates(currentNode, tt);
tt = tt->getNextTreeTop();
}
}
// New code: without using any UDI
// walk through the trees in the loop
// to invalidate the candidates
//
if (!_supportedExpressions)
{
_supportedExpressions = new (trStackMemory()) TR_BitVector(comp()->getNodeCount(), trMemory(), stackAlloc, growable);
}
invalidateCandidates();
ListIterator<SimplificationCandidateTuple> candidates(_candidates);
for (SimplificationCandidateTuple *nextCandidate = candidates.getFirst(); nextCandidate; nextCandidate = candidates.getNext())
{
TR::TreeTop *treeTop = nextCandidate->getTreeTop();
if (trace())
{
nextCandidate->print(comp());
}
bool usedCandidate = false;
bool isPreheaderBlockInvalid = false;
if (canReduceSummations && nextCandidate->isSummationReductionCandidate())
{
usedCandidate = tranformSummationReductionCandidate(treeTop, loopInfo, &isPreheaderBlockInvalid);
}
if (isPreheaderBlockInvalid)
{
break;
}
if (!usedCandidate && nextCandidate->isInvariantExpressionCandidate())
{
tranformStoreMotionCandidate(treeTop, &isPreheaderBlockInvalid);
}
if (isPreheaderBlockInvalid)
{
break;
}
}
}
void TR_ExpressionsSimplification::setSummationReductionCandidates(TR::Node *node, TR::TreeTop *tt)
{
// Must be a store node
//
if (node->getOpCodeValue() != TR::istore
/* || node->getOpCodeValue() != TR::astore */)
{
if (trace())
traceMsg(comp(), "Node %p: The opcode is not istore so not a summation reduction candidate\n",node);
return;
}
TR::Node *opNode = node->getFirstChild();
if (opNode->getOpCodeValue() == TR::iadd ||
opNode->getOpCodeValue() == TR::isub)
{
TR::Node *firstNode = opNode->getFirstChild();
TR::Node *secondNode = opNode->getSecondChild();
if (firstNode->getOpCode().hasSymbolReference() &&
node->getSymbolReference() == firstNode->getSymbolReference() &&
opNode->getReferenceCount() == 1 && firstNode->getReferenceCount() == 1)
{
// The second node must be loop invariant
//
if (!_currentRegion->isExprInvariant(secondNode))
{
if (trace())
{
traceMsg(comp(), "The node %p is not loop invariant\n",secondNode);
// This can be the arithmetic series case
// only when the node is an induction variable
if (secondNode->getNumChildren() == 1 && secondNode->getOpCode().hasSymbolReference())
{
TR_InductionVariable *indVar = _currentRegion->findMatchingIV(secondNode->getSymbolReference());
if (indVar)
{
//printf("Found Candidate of arithmetic series\n" );
}
}
}
return;
}
_candidates->add(new (trStackMemory()) SimplificationCandidateTuple(tt,
flags32_t(SimplificationCandidateTuple::SummationReductionCandidate)));
}
else if (secondNode->getOpCode().hasSymbolReference() &&
node->getSymbolReference() == secondNode->getSymbolReference() &&
opNode->getReferenceCount() == 1 && secondNode->getReferenceCount() == 1 &&
_currentRegion->isExprInvariant(firstNode))
{
_candidates->add(new (trStackMemory()) SimplificationCandidateTuple(tt,
flags32_t(SimplificationCandidateTuple::SummationReductionCandidate)));
}
}
else if (opNode->getOpCodeValue() == TR::ixor ||
opNode->getOpCodeValue() == TR::ineg)
{
if (opNode->getFirstChild()->getOpCode().hasSymbolReference() &&
node->getSymbolReference() == opNode->getFirstChild()->getSymbolReference() &&
opNode->getReferenceCount() == 1 && opNode->getFirstChild()->getReferenceCount() == 1 &&
(opNode->getOpCodeValue() == TR::ineg || _currentRegion->isExprInvariant(opNode->getSecondChild())))
{
_candidates->add(new (trStackMemory()) SimplificationCandidateTuple(tt,
flags32_t(SimplificationCandidateTuple::SummationReductionCandidate)));
}
else if (opNode->getOpCodeValue() == TR::ixor && opNode->getSecondChild()->getOpCode().hasSymbolReference() &&
node->getSymbolReference() == opNode->getSecondChild()->getSymbolReference() &&
opNode->getReferenceCount() == 1 && opNode->getSecondChild()->getReferenceCount() == 1 &&
_currentRegion->isExprInvariant(opNode->getFirstChild()))
{
_candidates->add(new (trStackMemory()) SimplificationCandidateTuple(tt,
flags32_t(SimplificationCandidateTuple::SummationReductionCandidate)));
}
}
}
void TR_ExpressionsSimplification::setStoreMotionCandidates(TR::Node *node, TR::TreeTop *tt)
{
// Must be a store node, of any type but not holding a monitor object
//
if (node->getOpCode().isStore() &&
!node->getSymbol()->isStatic() &&
!node->getSymbol()->holdsMonitoredObject())
{
if (trace())
traceMsg(comp(), "Node %p: The opcode is a non-static, non-monitor object store\n", node);
for (int32_t i = 0; i < node->getNumChildren(); i++)
{
if (!_currentRegion->isExprInvariant(node->getChild(i)))
{
if (trace())
traceMsg(comp(), "Node %p: The store is not loop-invariant due to child %p\n", node, node->getChild(i));
return;
}
}
// If store's operands are loop-invariant
if (trace())
{
traceMsg(comp(), "Node %p: The store's operands are all loop-invariant, adding candidate\n", node);
traceMsg(comp(), "Node %p: - value of isExprInvariant for the store itself is %s\n", node, _currentRegion->isExprInvariant(node) ? "true" : "false");
}
_candidates->add(new (trStackMemory()) SimplificationCandidateTuple(tt,
SimplificationCandidateTuple::InvariantExpressionCandidate));
}
}
bool TR_ExpressionsSimplification::tranformSummationReductionCandidate(TR::TreeTop *treeTop, LoopInfo *loopInfo, bool *isPreheaderBlockInvalid)
{
TR::Node *node = treeTop->getNode();
TR::Node *opNode = node->getFirstChild();
TR::Node *expNode = NULL;
int32_t expChildNumber = 0;
bool removeOnly = false;
bool replaceWithNewNode = false;
if (opNode->getOpCodeValue() == TR::iadd || opNode->getOpCodeValue() == TR::isub)
{
if (opNode->getSecondChild()->getOpCode().hasSymbolReference() &&
node->getSymbolReference() == opNode->getSecondChild()->getSymbolReference())
{
expChildNumber = 0;
expNode = opNode->getFirstChild();
}
else
{
expChildNumber = 1;
expNode = opNode->getSecondChild();
}
expNode = iaddisubSimplifier(expNode, loopInfo);
replaceWithNewNode = true;
}
else if (opNode->getOpCodeValue() == TR::ixor || opNode->getOpCodeValue() == TR::ineg)
{
expNode = ixorinegSimplifier(opNode, loopInfo, &removeOnly);
}
if (expNode)
{
if (trace())
comp()->getDebug()->print(comp()->getOutFile(), expNode, 0, true);
TR::Block *entryBlock = _currentRegion->getEntryBlock();
TR::Block *preheaderBlock = findPredecessorBlock(entryBlock);
if (!preheaderBlock)
{
if (trace())
traceMsg(comp(), "Fail to find a place to put the hoist code in\n");
*isPreheaderBlockInvalid = true;
return true;
}
if (loopInfo->getNumIterations() > 0 || // make sure that the loop is going to be executed at least once
_currentRegion->isCanonicalizedLoop()) // or that the loop is canonicalized, in which case the preheader is
{ // executed in its first iteration and is protected.
if (performTransformation(comp(), "%sMove out reduction node [%p] to block_%d\n", OPT_DETAILS, node, preheaderBlock->getNumber()))
{
if (!(removeOnly))
{
TR::Node *newNode = node->duplicateTree();
if (replaceWithNewNode)
newNode->getFirstChild()->setAndIncChild(expChildNumber, expNode);
transformNode(newNode, preheaderBlock);
}
TR::TransformUtil::removeTree(comp(), treeTop);
}
}
}
return (expNode != NULL);
}
void TR_ExpressionsSimplification::tranformStoreMotionCandidate(TR::TreeTop *treeTop, bool *isPreheaderBlockInvalid)
{
TR::Node *node = treeTop->getNode();
TR_ASSERT(node->getOpCode().isStore() && !node->getSymbol()->isStatic() && !node->getSymbol()->holdsMonitoredObject(),
"node %p was expected to be a non-static non-monitored object store and was not.", node);
// this candidate should be valid, either direct or indirect
if (trace())
comp()->getDebug()->print(comp()->getOutFile(), node, 0, true);
TR::Block *entryBlock = _currentRegion->getEntryBlock();
TR::Block *preheaderBlock = findPredecessorBlock(entryBlock);
if (!preheaderBlock)
{
if (trace())
traceMsg(comp(), "Fail to find a place to put the hoist code in\n");
*isPreheaderBlockInvalid = true;
return;
}
// Earlier post-dominance test ensures that the loop is executed as least once, or is canonicalized.
// but to be safe we still perform on canonicalized loops only.
if (_currentRegion->isCanonicalizedLoop()) // make sure that the loop is canonicalized, in which case the preheader is
{ // executed in its first iteration and is protected.
if (performTransformation(comp(), "%sMove out loop-invariant store [%p] to block_%d\n", OPT_DETAILS, node, preheaderBlock->getNumber()))
{
TR::Node *newNode = node->duplicateTree();
transformNode(newNode, preheaderBlock);
TR::TransformUtil::removeTree(comp(), treeTop);
}
}
else
{
if (trace())
traceMsg(comp(), "No canonicalized loop for this candidate\n");
}
}
void
TR_ExpressionsSimplification::invalidateCandidates()
{
_visitCount = comp()->incVisitCount();
if (trace())
{
traceMsg(comp(), "Checking which candidates may be invalidated\n");
ListIterator<SimplificationCandidateTuple> candidates(_candidates);
for (SimplificationCandidateTuple *nextCandidate = candidates.getFirst(); nextCandidate; nextCandidate = candidates.getNext())
{
nextCandidate->print(comp());
}
}
TR_ScratchList<TR::Block> blocksInLoop(trMemory());
_currentRegion->getBlocks(&blocksInLoop);
ListIterator<TR::Block> blocks(&blocksInLoop);
for (TR::Block *currentBlock = blocks.getFirst(); currentBlock; currentBlock = blocks.getNext())
{
TR::TreeTop *tt = currentBlock->getEntry();
TR::TreeTop *exitTreeTop = currentBlock->getExit();
while (tt != exitTreeTop)
{
TR::Node *currentNode = tt->getNode();
if (trace())
traceMsg(comp(), "Looking at treeTop [%p]\n", currentNode);
removeCandidate(currentNode, tt);
tt = tt->getNextTreeTop();
}
}
removeUnsupportedCandidates();
}
void
TR_ExpressionsSimplification::removeUnsupportedCandidates()
{
ListIterator<SimplificationCandidateTuple> candidates(_candidates);
for (SimplificationCandidateTuple *nextCandidate = candidates.getFirst(); nextCandidate; nextCandidate = candidates.getNext())
{
TR::TreeTop *candidateTT = nextCandidate->getTreeTop();
TR::Node *candidateNode = candidateTT->getNode();
if (!_supportedExpressions->get(candidateNode->getGlobalIndex()))
{
if (trace())
traceMsg(comp(), "Removing candidate %p which is unsupported or has unsupported subexpressions\n", candidateNode);
_candidates->remove(nextCandidate);
}
}
}
void
TR_ExpressionsSimplification::removeCandidate(TR::Node *node, TR::TreeTop* tt)
{
if (node->getVisitCount() == _visitCount)
return;
node->setVisitCount(_visitCount);
if (trace())
traceMsg(comp(), "Looking at Node [%p]\n", node);
ListIterator<SimplificationCandidateTuple> candidates(_candidates);
for (SimplificationCandidateTuple *nextCandidate = candidates.getFirst(); nextCandidate; nextCandidate = candidates.getNext())
{
TR::TreeTop *candidateTT = nextCandidate->getTreeTop();
if (tt != candidateTT &&
node->getOpCode().hasSymbolReference() &&
candidateTT->getNode()->mayKill(true).contains(node->getSymbolReference(), comp()))
{
if (trace())
traceMsg(comp(), "Removing candidate %p which has aliases in the loop\n", candidateTT->getNode());
_candidates->remove(nextCandidate);
continue;
}
}
bool hasSupportedChildren = true;
// Process the children as well
//
for (int32_t i = 0; i < node->getNumChildren(); i++)
{
removeCandidate(node->getChild(i), tt);
// candidates child expressions must be invariant and supported. Here we determine if they are supported.
if (!_supportedExpressions->get(node->getChild(i)->getGlobalIndex()))
{
hasSupportedChildren = false;
}
}
if (hasSupportedChildren && isSupportedNodeForExpressionSimplification(node))
{
_supportedExpressions->set(node->getGlobalIndex());
}
else
{
if (trace())
traceMsg(comp(), " Node %p is unsupported expression because %s\n", node,
!hasSupportedChildren ? "it has unsupported children" : "it is itself unsupported");
}
}
bool
TR_ExpressionsSimplification::isSupportedNodeForExpressionSimplification(TR::Node *node)
{
// types of stores that may be supported by loop invariant store motion
bool isSupportedStoreNode = node->getOpCode().isStore();
return TR_LocalAnalysis::isSupportedNodeForFunctionality(node, comp(), NULL, isSupportedStoreNode);
}
static bool examineNode(TR::Node *node, intptr_t visitCount)
{
if (node->getVisitCount() == visitCount)
return false;
node->setVisitCount(static_cast<vcount_t>(visitCount));
if (node->getOpCode().isCall())
return true;
bool hasCalls = false;
for (int32_t i = 0; !hasCalls && i < node->getNumChildren(); i++)
{
hasCalls = examineNode(node->getChild(i), visitCount);
}
return hasCalls;
}
static bool blockHasCalls(TR::Block *block, TR::Compilation *comp)
{
intptr_t visitCount = comp->incVisitCount();
TR::TreeTop *currentTree = block->getEntry();
TR::TreeTop *exitTree = block->getExit();
bool hasCalls = false;
while (!hasCalls && currentTree != exitTree)
{
hasCalls = examineNode(currentTree->getNode(), visitCount);
currentTree = currentTree->getNextTreeTop();
}
return hasCalls;
}
void
TR_ExpressionsSimplification::removeUncertainBlocks(TR_RegionStructure* region, List<TR::Block> *candidateBlocksList)
{
// Examine the top region block first
//
TR::Block *entryBlock = region->getEntryBlock();
ListIterator<TR::Block> blocks;
blocks.set(candidateBlocksList);
if (trace())
traceMsg(comp(), "Number of blocks %d, entry block number %d\n", candidateBlocksList->getSize(), entryBlock->getNumber());
for (TR::Block *block = blocks.getFirst(); block; block = blocks.getNext())
{
TR::CFGNode *cfgNode = block;
if (!(cfgNode->getExceptionSuccessors().empty()) || blockHasCalls(block, comp()))
{
if (trace())
traceMsg(comp(), "An exception can be thrown from block_%d. Removing all the blocks, since we cannot know the number of iterations.\n", block->getNumber());
candidateBlocksList->deleteAll();
break;
}
}
TR_PostDominators postDominators(comp());
if (postDominators.isValid())
{
postDominators.findControlDependents();
for (TR::Block *block = blocks.getFirst(); block; block = blocks.getNext())
{
if (postDominators.dominates(block, entryBlock) == 0)
{
candidateBlocksList->remove(block);
if (trace())
traceMsg(comp(), "Block_%d is not guaranteed to be executed at least once. Removing it from the list.\n", block->getNumber());
}
else
{
// If the block is within another loop that's nested in
// the current region, remove it from consideration - blocks
// must be executed exactly once in the loop to be considered
TR_BlockStructure *blockStructure = block->getStructureOf();
TR_Structure *parent = blockStructure->getParent();
while (parent != NULL)
{
TR_RegionStructure *parentRegion = parent->asRegion();
if (parentRegion == region)
{
break;
}
if (parentRegion->isNaturalLoop() || parentRegion->containsInternalCycles())
{
candidateBlocksList->remove(block);
if (trace())
{
traceMsg(comp(), "Block_%d is nested within another loop in the current loop. Removing it from the list.\n", block->getNumber());
}
break;
}
parent = parent->getParent();
}
}
}
}
else
{
if (trace())
traceMsg(comp(), "There is no post dominators information. Removing all the blocks.\n");
for (TR::Block *block = blocks.getFirst(); block; block = blocks.getNext())
{
candidateBlocksList->remove(block);
if (trace())
traceMsg(comp(), "Block_%d is removed from the list\n", block->getNumber());
}
}
}
TR_ExpressionsSimplification::LoopInfo*
TR_ExpressionsSimplification::findLoopInfo(TR_RegionStructure* region)
{
ListIterator<TR::CFGEdge> exitEdges(®ion->getExitEdges());
if (region->getExitEdges().getSize() != 1)
{
if (trace())
traceMsg(comp(), "Region with more than 1 exit edges can't be handled\n");
return 0;
}
TR::CFGEdge *exitEdge = exitEdges.getFirst();
TR_StructureSubGraphNode* exitNode = toStructureSubGraphNode(exitEdge->getFrom());
int32_t exitTarget = exitEdge->getTo()->getNumber();
if (!exitNode->getStructure()->asBlock())
{
if (trace())
traceMsg(comp(), "The exit block can't be found\n");
return 0;
}
TR::Block *exitBlock = exitNode->getStructure()->asBlock()->getBlock();
TR::Node *lastTreeInExitBlock = exitBlock->getLastRealTreeTop()->getNode();
if (trace())
{
traceMsg(comp(), "The exit block is %d\n", exitBlock->getNumber());
traceMsg(comp(), "The branch node is %p\n", lastTreeInExitBlock);
}
if (!lastTreeInExitBlock->getOpCode().isBranch())
{
if (trace())
traceMsg(comp(), "The branch node couldn't be found\n");
return 0;
}
if (lastTreeInExitBlock->getNumChildren() < 2)
{
if (trace())
traceMsg(comp(), "The branch node has less than 2 children\n");
return 0;
}
TR::Node *firstChildOfLastTree = lastTreeInExitBlock->getFirstChild();
TR::Node *secondChildOfLastTree = lastTreeInExitBlock->getSecondChild();
if (!firstChildOfLastTree->getOpCode().hasSymbolReference())
{
if (trace())
traceMsg(comp(), "The branch node's first child node %p - its opcode does not have a symbol reference\n", firstChildOfLastTree);
return 0;
}
TR::SymbolReference *firstChildSymRef = firstChildOfLastTree->getSymbolReference();
if (trace())
traceMsg(comp(), "Symbol Reference: %p Symbol: %p\n", firstChildSymRef, firstChildSymRef->getSymbol());
// Locate the induction variable that matches with the exit node symbol
//
TR_InductionVariable *indVar = region->findMatchingIV(firstChildSymRef);
if (!indVar) return 0;
if (!indVar->getIncr()->asIntConst())
{
if (trace())
traceMsg(comp(), "Increment is not a constant\n");
return 0;
}
int32_t increment = indVar->getIncr()->getLowInt();
_visitCount = comp()->incVisitCount();
bool indVarWrittenAndUsedUnexpectedly = false;
if (firstChildOfLastTree->getReferenceCount() > 1)
{
TR::TreeTop *cursorTreeTopInExitBlock = exitBlock->getEntry();
TR::TreeTop *exitTreeTopInExitBlock = exitBlock->getExit();
bool loadSeen = false;
while (cursorTreeTopInExitBlock != exitTreeTopInExitBlock)
{
TR::Node *cursorNode = cursorTreeTopInExitBlock->getNode();
if (checkForLoad(cursorNode, firstChildOfLastTree))
loadSeen = true;
if (!cursorNode->getOpCode().isStore() &&
(cursorNode->getNumChildren() > 0))
cursorNode = cursorNode->getFirstChild();
if (cursorNode->getOpCode().isStore() &&
(cursorNode->getSymbolReference() == firstChildSymRef))
{
indVarWrittenAndUsedUnexpectedly = true;
if ((cursorNode->getFirstChild() == firstChildOfLastTree) ||
!loadSeen)
indVarWrittenAndUsedUnexpectedly = false;
else
break;
}
cursorTreeTopInExitBlock = cursorTreeTopInExitBlock->getNextTreeTop();
}
}
if (indVarWrittenAndUsedUnexpectedly)
{
return 0;
}
int32_t lowerBound;
int32_t upperBound = 0;
TR::Node *bound = 0;
bool equals = false;
switch(lastTreeInExitBlock->getOpCodeValue())
{
case TR::ificmplt:
case TR::ificmpgt:
equals = true;
case TR::ificmple:
case TR::ificmpge:
{
TR::TreeTop *branchDestTT = lastTreeInExitBlock->getBranchDestination();
TR::Block *branchDest = branchDestTT->getNode()->getBlock();
if (branchDest->getNumber() != exitTarget)
equals = !equals;
if (!(indVar->getEntry() && indVar->getEntry()->asIntConst()))
{
if (trace())
traceMsg(comp(), "Entry value is not a constant\n");
return 0;
}
lowerBound = indVar->getEntry()->getLowInt();
if (secondChildOfLastTree->getOpCode().isLoadConst())
{
upperBound = secondChildOfLastTree->getInt();
}
else if (secondChildOfLastTree->getOpCode().isLoadVar())
{
bound = secondChildOfLastTree;
}
else
{
if (trace())
traceMsg(comp(), "Second child is not a const or a load\n");
return 0;
}
return new (trStackMemory()) LoopInfo(bound, lowerBound, upperBound, increment, equals);
}
default:
if (trace())
traceMsg(comp(), "The condition has not been implemeted\n");
return 0;
}
return 0;
}
bool
TR_ExpressionsSimplification::checkForLoad(TR::Node *node, TR::Node *load)
{
if (node->getVisitCount() == _visitCount)
return false;
node->setVisitCount(_visitCount);
if (node == load)
return true;
for (int32_t i = 0; i < node->getNumChildren(); i++)
{
if (checkForLoad(node->getChild(i), load))
return true;
}
return false;
}
TR::Node *
TR_ExpressionsSimplification::iaddisubSimplifier(TR::Node *invariantNode, LoopInfo* loopInfo)
{
TR_ASSERT_FATAL(
loopInfo->getBoundaryNode() == NULL,
"iteration count must be constant for loop %d",
_currentRegion->getNumber());
int32_t iters = loopInfo->getNumIterations();
TR_ASSERT_FATAL(
iters > 0,
"iteration count (%d) must be known and positive for loop %d",
iters,
_currentRegion->getNumber());
return TR::Node::create(
invariantNode,
TR::imul,
2,
invariantNode->duplicateTree(),
TR::Node::create(invariantNode, TR::iconst, 0, iters));
}
TR::Node *
TR_ExpressionsSimplification::ixorinegSimplifier(TR::Node *node, LoopInfo* loopInfo, bool *removeOnly)
{
TR::Node *newNode = 0;
*removeOnly = false;
if (loopInfo->getBoundaryNode())
{
if (trace())
traceMsg(comp(), "Loop has a non constant boundary, but this case is not taken care of\n");
}
else
{
if (loopInfo->getNumIterations() > 0)
{
newNode = node;
if (loopInfo->getNumIterations() % 2 == 0)
{
*removeOnly = true;
}
}
}
return newNode;
}
TR::Block *
TR_ExpressionsSimplification::findPredecessorBlock(TR::CFGNode *entryNode)
{
if (!(entryNode->getPredecessors().size() == 2))
return 0;
TR::Block *block = 0;
for (auto edge = entryNode->getPredecessors().begin(); edge != entryNode->getPredecessors().end(); ++edge)
{
if ((*edge)->getFrom()->getSuccessors().size() == 1)
{
block = toBlock((*edge)->getFrom());
if (block->getStructureOf()->isLoopInvariantBlock())
break;
else