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LocalOpts.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/LocalOpts.hpp"
#include <algorithm>
#include <limits.h>
#include <math.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "codegen/CodeGenerator.hpp"
#include "env/FrontEnd.hpp"
#include "env/KnownObjectTable.hpp"
#include "codegen/RecognizedMethods.hpp"
#include "codegen/RegisterConstants.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 "control/Recompilation.hpp"
#include "cs2/bitvectr.h"
#include "cs2/hashtab.h"
#include "cs2/llistof.h"
#include "cs2/sparsrbit.h"
#include "env/CompilerEnv.hpp"
#include "env/HeuristicRegion.hpp"
#include "env/PersistentInfo.hpp"
#include "env/StackMemoryRegion.hpp"
#include "env/TRMemory.hpp"
#include "env/jittypes.h"
#include "il/AliasSetInterface.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/NodePool.hpp"
#include "il/Node_inlines.hpp"
#include "il/ParameterSymbol.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 "ilgen/IlGenRequest.hpp"
#include "ilgen/IlGeneratorMethodDetails.hpp"
#include "infra/Array.hpp"
#include "infra/Assert.hpp"
#include "infra/Bit.hpp"
#include "infra/BitVector.hpp"
#include "infra/Cfg.hpp"
#include "infra/ILWalk.hpp"
#include "infra/Link.hpp"
#include "infra/List.hpp"
#include "optimizer/Inliner.hpp"
#include "infra/Stack.hpp"
#include "infra/CfgEdge.hpp"
#include "infra/CfgNode.hpp"
#include "optimizer/Optimization.hpp"
#include "optimizer/Optimization_inlines.hpp"
#include "optimizer/OptimizationManager.hpp"
#include "optimizer/Optimizations.hpp"
#include "optimizer/Optimizer.hpp"
#include "optimizer/OrderBlocks.hpp"
#include "optimizer/PreExistence.hpp"
#include "optimizer/Structure.hpp"
#include "optimizer/TransformUtil.hpp"
#include "optimizer/UseDefInfo.hpp"
#include "ras/Debug.hpp"
#include "ras/DebugCounter.hpp"
#include "ras/ILValidator.hpp"
#include "ras/ILValidationStrategies.hpp"
#include "runtime/Runtime.hpp"
#include "env/VMAccessCriticalSection.hpp"
#ifdef J9_PROJECT_SPECIFIC
#include "control/RecompilationInfo.hpp"
#include "runtime/J9ValueProfiler.hpp"
#include "runtime/J9Profiler.hpp"
#include "env/CHTable.hpp"
#include "env/ClassTableCriticalSection.hpp"
#include "env/PersistentCHTable.hpp"
#include "env/RuntimeAssumptionTable.hpp"
#include "env/VMJ9.h"
#include "runtime/RuntimeAssumptions.hpp"
#endif
// basic blocks peephole optimization.
// Return "true" if any basic block peephole optimization was done
TR_PeepHoleBasicBlocks::TR_PeepHoleBasicBlocks(TR::OptimizationManager *manager)
: TR_BlockManipulator(manager)
{}
int32_t TR_PeepHoleBasicBlocks::perform()
{
// The CFG must exist for this optimization
//
TR::CFG * cfg = comp()->getFlowGraph();
if (cfg == NULL || comp()->getOption(TR_DisableBasicBlockPeepHole))
return 0;
TR_OrderBlocks orderBlocks(manager());
cfg->setIgnoreUnreachableBlocks(true);
int32_t rc = orderBlocks.lookForPeepHoleOpportunities("O^O BLOCK PEEP HOLE: ");
cfg->setIgnoreUnreachableBlocks(false);
if(cfg->getHasUnreachableBlocks())
cfg->removeUnreachableBlocks();
return rc;
}
const char *
TR_PeepHoleBasicBlocks::optDetailString() const throw()
{
return "O^O BASIC BLOCK PEEPHOLE: ";
}
// Extend basic blocks.
// Return "true" if any basic block extension was done
TR_ExtendBasicBlocks::TR_ExtendBasicBlocks(TR::OptimizationManager *manager)
: TR_BlockManipulator(manager)
{}
int32_t TR_ExtendBasicBlocks::perform()
{
// The CFG must exist for this optimization
//
static const char *disableFreqCBO = feGetEnv("TR_disableFreqCBO");
int32_t orderBlocksResult=-5;
if (comp()->getFlowGraph() == NULL)
return 0;
// There are two basic block extension algorithms depending on whether or not
// block and edge frequencies are known,
//
if (true)
{
static const char *p = feGetEnv("TR_OlderBlockReordering");
if (p)
return orderBlocksWithFrequencyInfo();
}
if (!comp()->getOption(TR_DisableNewBlockOrdering))
{
TR_OrderBlocks orderBlocks(manager());
orderBlocks.extendBlocks();
orderBlocksResult = orderBlocks.perform();
// comp()->getFlowGraph()->setStructure(NULL); TR_OrderBlocks should reset structure if needed
return orderBlocksResult;
}
orderBlocksResult = orderBlocksWithoutFrequencyInfo();
if (!disableFreqCBO)
comp()->getFlowGraph()->setStructure(NULL);
return orderBlocksResult;
}
int32_t TR_ExtendBasicBlocks::orderBlocksWithoutFrequencyInfo()
{
// TR_Structure *rootStructure = NULL;
//
// Set up the block nesting depths
//
TR::CFG *cfg = comp()->getFlowGraph();
TR_Structure *rootStructure = cfg->getStructure();
if (rootStructure)
{
TR::CFGNode *node;
for (node = cfg->getFirstNode(); node; node = node->getNext())
{
TR::Block *block = toBlock(node);
int32_t nestingDepth = 0;
if (block->getStructureOf() != NULL)
block->getStructureOf()->setNestingDepths(&nestingDepth);
}
}
//markColdBlocks();
TR::TreeTop *endTreeTop = comp()->getMethodSymbol()->getLastTreeTop();
vcount_t visitCount = comp()->incVisitCount();
bool blocksWereExtended = false;
TR::Block * prevBlock = comp()->getStartTree()->getNode()->getBlock();
//prevBlock->setVisitCount(visitCount);
TR::Block * block = prevBlock->getNextBlock();
bool reattemptThisExtension = false;
for (; block; prevBlock = block, block = block->getNextBlock())
{
if (!reattemptThisExtension &&
(block->getVisitCount() == visitCount))
continue;
reattemptThisExtension = false;
prevBlock->setVisitCount(visitCount);
if (block->isExtensionOfPreviousBlock())
continue;
// Check that the previous block doesn't end with a switch.
//
TR::TreeTop * tt = prevBlock->getLastRealTreeTop();
TR::Node * prevNode = tt->getNode();
if(prevNode->getOpCodeValue() == TR::treetop)
prevNode = prevNode->getFirstChild();
if ( prevNode->getOpCode().isJumpWithMultipleTargets() || !prevBlock->hasSuccessor(block))
continue;
TR::CFGEdgeList & preds = block->getPredecessors();
bool cannotExtendWithCurrentFallThrough = false;
if (!(preds.size() == 1))
cannotExtendWithCurrentFallThrough = true;
TR::Block *bestExtension = NULL;
if (trace())
traceMsg(comp(), " Current block [%d] looking for best successor to extend it...\n", prevBlock->getNumber());
//int32_t blockHotness = block->getHotness(cfg);
int32_t blockFreq = block->getFrequency();
if (block->isCold() || (blockFreq >= 0))
{
bestExtension = getBestChoiceForExtension(prevBlock);
//
// If the only choice for extension is dead cold (frequency == 0)
// then do not extend even if it is possible. This is done to avoid
// cases where we will extend with a colder block than the original
// fall through (which was hotter).
//
if (cannotExtendWithCurrentFallThrough && bestExtension)
{
if (block != bestExtension)
{
//int32_t bestHotness = bestExtension->getHotness(cfg);
int32_t bestFreq = bestExtension->getFrequency();
if (!block->isCold() &&
(blockFreq >= 0) && (bestFreq >= 0))
//(blockHotness != unknownHotness) && (bestHotness != unknownHotness))
{
//if (((bestHotness == deadCold) && (blockHotness != deadCold)) || (blockHotness > (bestHotness + 1)))
if ((((bestFreq == (MAX_COLD_BLOCK_COUNT+1)) && (blockFreq != (MAX_COLD_BLOCK_COUNT+1))) || (blockFreq > bestFreq + 100)))
{
//bestExtension = NULL;
continue;
}
}
}
}
}
if (trace())
traceMsg(comp(), " Current block [%d] with freq %d, best extension is BB[%d]\n", prevBlock->getNumber(), block->getFrequency(), bestExtension?bestExtension->getNumber():-1);
if (cannotExtendWithCurrentFallThrough ||
(bestExtension &&
!bestExtension->isCold() &&
(bestExtension != block)))
{
//
// The prevBlock cannot be extended to include the current block.
// See if the prevBlock has a successor whose only predecessor is the prevBlock.
// If so, see if we can rearrange the blocks so that the prevBlock can be extended
// without adding any new gotos.
//
TR::Block * newBlock = 0;
if (!bestExtension)
{
TR::CFGEdgeList & prevSuccessors = prevBlock->getSuccessors();
for (auto e = prevSuccessors.begin(); e != prevSuccessors.end(); ++e)
if ((*e)->getTo()->getPredecessors().size() == 1)
{ newBlock = toBlock((*e)->getTo()); break; }
}
else
newBlock = bestExtension;
if (!newBlock)
continue; // there's no way to extend the prevBlock
if (!prevBlock->isCold() && newBlock->isCold()) continue;
// See if we can easily move the current block without adding a new goto.
//
TR::Block * lastBlockToMove = block, * next;
for (;; lastBlockToMove = next)
{
next = lastBlockToMove->getNextBlock();
if (!next || !lastBlockToMove->hasSuccessor(next))
break;
//if (!(next->getPredecessors().size() == 1))
// { lastBlockToMove = 0; break; }
}
if (lastBlockToMove)
{
TR::TreeTop *previousTree = newBlock->getEntry()->getPrevTreeTop();
if (newBlock->getPredecessors().size() == 1)
{
int32_t result = performChecksAndTreesMovement(newBlock, prevBlock, block, endTreeTop, visitCount, optimizer());
if (result < 0)
{
if (cannotExtendWithCurrentFallThrough)
continue;
}
else
{
if (result == 1)
endTreeTop = previousTree;
block = newBlock;
}
}
else
{
if (cannotExtendWithCurrentFallThrough)
continue;
}
}
else
{
if (cannotExtendWithCurrentFallThrough)
continue;
}
}
// This block can be merged with the preceding block
//
TR::TreeTop *firstNonFenceTree = block->getFirstRealTreeTop();
TR::TreeTop *lastNonFenceTree = block->getLastRealTreeTop();
if (prevNode->getOpCodeValue() == TR::Goto)
{
if (!performTransformation(comp(), "%sMerge blocks %d and %d\n", optDetailString(), prevBlock->getNumber(), block->getNumber()))
continue;
optimizer()->prepareForTreeRemoval(tt);
TR::TransformUtil::removeTree(comp(), tt);
}
else if ((firstNonFenceTree == lastNonFenceTree) &&
(lastNonFenceTree->getNode()->getOpCodeValue() == TR::Goto)
)
{
TR::Block * nextBlock = block->getNextBlock();
if (nextBlock && prevNode->getOpCode().isBranch() && !prevNode->isNopableInlineGuard())
{
TR::TreeTop *gotoDest = lastNonFenceTree->getNode()->getBranchDestination();
TR::Block * prevBranchDest = prevNode->getBranchDestination()->getNode()->getBlock();
if (prevNode->getBranchDestination() == nextBlock->getEntry() && !nextBlock->isCold())
{
if (!performTransformation(comp(), "%sReverse branch in block_%d\n", optDetailString(), prevBlock->getNumber()))
continue;
for (auto c = 0; c < prevNode->getNumChildren(); ++c)
{
TR_ASSERT(prevNode->getChild(c)->getOpCodeValue() != TR::GlRegDeps, "the conditional branch node has a GlRegDep child and we're changing control flow");
}
prevNode->reverseBranch(gotoDest);
TR::Block *gotoDestBlock = gotoDest->getNode()->getBlock();
if (!prevBlock->hasSuccessor(gotoDestBlock))
cfg->addEdge(prevBlock, gotoDestBlock);
cfg->removeEdge(block, gotoDestBlock);
cfg->removeEdge(prevBlock, block);
prevBlock->getExit()->join(nextBlock->getEntry());
block = prevBlock;
reattemptThisExtension = true;
continue;
}
else if (prevBranchDest->getVisitCount() < visitCount &&
prevBranchDest->getPredecessors().size() == 1)
{
// don't swing up cold blocks
if (prevBranchDest->isCold())
continue;
if (!performTransformation(comp(), "%sReverse branch in %d (possibly swinging up destintion and removign goto block_%d)\n", optDetailString(), prevBlock->getNumber(), block->getNumber()))
continue;
// snip T (and its fall-through-chain) and swing it upto F, reversing
// the branch in F, and potentially removing the goto block
//
TR::Block * F = prevBlock;
TR::Block * T = prevBranchDest;
TR::Block *pT = T->getPrevBlock();
TR::Block * G;
TR::Block *nG;
// if the F and pT are the same (we have a redundant compare) - do not do any transformation
if (F == pT) continue; // FIXME: maybe we should remove the redundant comparison
for (G = T, nG = G->getNextBlock();
nG && G->hasSuccessor(nG);
G = nG, nG = nG->getNextBlock())
;
if (nG)
pT->getExit()->join(nG->getEntry());
else
{
pT->getExit()->setNextTreeTop(0);
endTreeTop = pT->getExit();
}
F->getExit()->join(T->getEntry());
G->getExit()->join(block->getEntry());
TR_ASSERT(prevNode->getNumChildren() != 3, "the branch node has a GlRegDep child that we're about to invalidate");
prevNode->reverseBranch(gotoDest);
int32_t copiedFrequency = 0;
TR::CFGEdge *addedEdge = NULL;
if (!F->hasSuccessor(gotoDest->getNode()->getBlock()))
{
addedEdge = cfg->addEdge(F, gotoDest->getNode()->getBlock());
TR_SuccessorIterator ei(F);
for (TR::CFGEdge * edge = ei.getFirst(); edge != NULL; edge = ei.getNext())
{
if (edge->getTo() == block)
{
copiedFrequency = edge->getFrequency();
break;
}
}
addedEdge->setFrequency(copiedFrequency);
}
cfg->removeEdge(F, block); // ideally 'block' will become unreachable, and be removed
block = prevBlock;
reattemptThisExtension = true;
continue;
}
else if (gotoDest->getNode()->getBlock() == prevBlock->startOfExtendedBlock())
{
if (!performTransformation(comp(), "%sRemove backedge goto block_%d by reversing the branch in block_%d\n", optDetailString(), block->getNumber(), prevBlock->getNumber()))
continue;
// goto is a backedge, reverse branch, swap destinations between branch and goto
//
TR::TreeTop *prevDest = prevNode->getBranchDestination();
TR_ASSERT(prevNode->getNumChildren() != 3, "the branch node has a GlRegDep child that we're about to invalidate");
prevNode->reverseBranch(gotoDest);
cfg->addEdge (prevBlock, gotoDest->getNode()->getBlock());
cfg->addEdge (block, prevDest->getNode()->getBlock());
cfg->removeEdge(prevBlock, prevDest->getNode()->getBlock());
lastNonFenceTree->getNode()->setBranchDestination(prevDest);
cfg->removeEdge(block, gotoDest->getNode()->getBlock());
}
}
}
if (!performTransformation(comp(), "%sExtend blocks %d and %d\n", optDetailString(), prevBlock->getNumber(), block->getNumber()))
continue;
blocksWereExtended = true;
block->setIsExtensionOfPreviousBlock();
}
if (blocksWereExtended)
optimizer()->enableAllLocalOpts();
return 1; // actual cost
}
struct TR_SequenceEntry
{
TR_ALLOC(TR_Memory::Optimization)
TR_SequenceEntry *next;
TR::Block *block;
TR::Block *fallThrough;
};
struct TR_SequenceHead
{
TR_SequenceEntry *first;
TR_SequenceEntry *last;
};
int32_t TR_ExtendBasicBlocks::orderBlocksWithFrequencyInfo()
{
TR::StackMemoryRegion stackMemoryRegion(*trMemory());
// Build sequences of blocks that are joined by edges with the highest
// frequencies.
//
TR::CFG *cfg = comp()->getFlowGraph();
TR::Block *block = NULL;
TR::TreeTop *treeTop = NULL;
TR::Node *node = NULL;
TR_SequenceEntry *entry = NULL;
int32_t i = 0;
int32_t numBlocks = cfg->getNextNodeNumber();
int32_t bestFrequency = 0, bestFrom = 0, bestTo = 0;
// Array of sequences - the Nth entry is the sequence that starts with
// block N.
//
TR_SequenceHead *sequences = (TR_SequenceHead*)trMemory()->allocateStackMemory(numBlocks*sizeof(TR_SequenceHead));
memset(sequences, 0, numBlocks*sizeof(TR_SequenceHead));
// Initialize each sequence with a single block
//
block = toBlock(cfg->getStart());
entry = new (trStackMemory()) TR_SequenceEntry;
entry->next = NULL;
entry->block = block;
i = block->getNumber();
sequences[i].first = entry;
sequences[i].last = entry;
block = toBlock(cfg->getEnd());
entry = new (trStackMemory()) TR_SequenceEntry;
entry->next = NULL;
entry->block = block;
i = block->getNumber();
sequences[i].first = entry;
sequences[i].last = entry;
// Remember if this block falls through to the next block
//
entry->fallThrough = NULL;
for (block = comp()->getStartTree()->getNode()->getBlock(); block;
block = block->getNextBlock())
{
entry = new (trStackMemory()) TR_SequenceEntry;
entry->next = NULL;
entry->block = block;
i = block->getNumber();
sequences[i].first = entry;
sequences[i].last = entry;
// Remember if this block falls through to the next block
//
entry->fallThrough = NULL;
treeTop = block->getLastRealTreeTop();
node = treeTop->getNode();
if (node->getOpCode().isCheck() || node->getOpCodeValue() == TR::treetop)
node = node->getFirstChild();
if (node->getOpCode().isBranch())
{
if (node->getOpCode().isIf())
entry->fallThrough = block->getNextBlock();
}
else if (!node->getOpCode().isReturn() &&
!node->getOpCode().isJumpWithMultipleTargets() &&
node->getOpCodeValue() != TR::athrow)
{
entry->fallThrough = block->getNextBlock();
}
}
// Give a preference to edges that will result in an extended basic block.
// The preference amount is the amount that the edge frequency will be
// increased by. It is calculated from a percentage point amount, i.e.
// units of 1/100 of a percent.
//
static const char *p;
static int32_t extendedBlockPointPreference = (p = feGetEnv("TR_ExtendedBlockPoints")) ? atoi(p) : 500;
int32_t extendedBlockPreference = extendedBlockPointPreference * (MAX_BLOCK_COUNT+MAX_COLD_BLOCK_COUNT) / 10000;
if (trace())
traceMsg(comp(), "Start block re-ordering\n");
// Merge sequences
//
int32_t numSequences;
int32_t oldNumSequences = numBlocks+1;
for (numSequences = numBlocks; numSequences > 1 && numSequences < oldNumSequences; )
{
oldNumSequences = numSequences;
// Find the sequence that has the output edge to another sequence with
// the highest frequency
//
bestFrequency = -1;
for (i = 0; i < numBlocks; ++i)
{
if (!sequences[i].first)
continue; // This block already consumed
TR_SequenceEntry *currentBlockEntry = sequences[i].last;
for (auto edge = currentBlockEntry->block->getSuccessors().begin(); edge != currentBlockEntry->block->getSuccessors().end(); ++edge)
{
int32_t edgeTo = (*edge)->getTo()->getNumber();
if (edgeTo != i && sequences[edgeTo].first)
{
int32_t edgeFrequency = (*edge)->getFrequency();
if ((*edge)->getTo()->getPredecessors().size() == 1)
{
block = toBlock((*edge)->getFrom());
if (block->getExit() &&
!(block->getLastRealTreeTop()->getNode()->getOpCode().isJumpWithMultipleTargets()))
{
edgeFrequency += extendedBlockPreference;
}
}
if ((edgeFrequency > bestFrequency) ||
((edgeFrequency == bestFrequency) &&
(currentBlockEntry->fallThrough == (*edge)->getTo())))
{
bestFrequency = edgeFrequency;
bestFrom = i;
bestTo = edgeTo;
}
}
}
}
// Join the sequences
//
if (bestFrequency >= 0)
{
sequences[bestFrom].last->next = sequences[bestTo].first;
sequences[bestFrom].last = sequences[bestTo].last;
sequences[bestTo].first = NULL;
numSequences--;
if (trace())
traceMsg(comp(), " add %d to %d\n", bestTo, bestFrom);
}
}
if (trace())
for (int32_t i = 0; i < numBlocks; ++i)
{
if (sequences[i].first != NULL)
{
traceMsg(comp(), "Seq %3d: ", i);
for (TR_SequenceEntry *entry = sequences[i].first; entry; entry = entry->next)
{
TR::Block *block = entry->block;
traceMsg(comp(), "%3d(%5d) ", block->getNumber(), block->getFrequency());
}
traceMsg(comp(), "\n");
}
}
bool blocksWereExtended = false;
// Now reorder the blocks so that the sequence containing the entry node is
// first, and order the rest in descending frequency of their first block.
//
TR::TreeTop *prevTree = NULL;
bestFrom = cfg->getStart()->getNumber();
while (bestFrom >= 0)
{
bool firstInSequence = true;
bool prevBlockHasSwitch = false;
for (entry = sequences[bestFrom].first; entry; entry = entry->next)
{
block = entry->block;
if (!block->getEntry())
continue;
if (trace())
traceMsg(comp(), " Insert block_%d %s\n", block->getNumber(), block->isCold() ? "cold" : "" );
// Join this block's trees to the previously processed block
//
if (prevTree)
prevTree->join(block->getEntry());
else
comp()->setStartTree(block->getEntry());
if (!firstInSequence && !prevBlockHasSwitch &&
(block->getPredecessors().size() == 1))
{
block->setIsExtensionOfPreviousBlock();
blocksWereExtended = true;
}
// See if the end of this block needs adjusting
//
treeTop = block->getLastRealTreeTop();
node = treeTop->getNode();
if (entry->next && entry->next->block->getEntry())
{
// This block will now fall through to the next block in the
// sequence
//
if (entry->fallThrough)
{
if (entry->next && entry->fallThrough == entry->next->block)
{
// The new fall-through block is the same as the original.
// There is nothing to do.
}
else
{
// This block originally fell through to a different block
//
TR_ASSERT(node->getOpCode().isIf(), "assertion failure");
node->reverseBranch(entry->fallThrough->getEntry());
}
}
else
{
// This block didn't fall through to anything. If it ended in a
// goto, the goto can be removed
//
if (node->getOpCodeValue() == TR::Goto)
{
optimizer()->prepareForTreeRemoval(treeTop);
TR::TransformUtil::removeTree(comp(), treeTop);
}
}
}
else
{
// This block will not fall through to any successor. If it
// originally did fall through, we must insert a goto to the
// original fallthrough target.
//
if (entry->fallThrough)
{
comp()->getFlowGraph()->setStructure(NULL);
TR::Block *extraBlock = TR::Block::createEmptyBlock(node, comp(), entry->fallThrough->getFrequency(), entry->fallThrough);
TR::TreeTop::create(comp(), extraBlock->getEntry(), TR::Node::create(node, TR::Goto, 0, entry->fallThrough->getEntry()));
block->getExit()->join(extraBlock->getEntry());
cfg->addNode(extraBlock);
cfg->addEdge(extraBlock, entry->fallThrough);
cfg->addEdge(block, extraBlock);
cfg->removeEdge(block, entry->fallThrough);
cfg->copyExceptionSuccessors(block, extraBlock);
block = extraBlock;
block->setIsExtensionOfPreviousBlock();
}
}
prevTree = block->getExit();
prevTree->setNextTreeTop(NULL);
firstInSequence = false;
prevBlockHasSwitch = node->getOpCode().isJumpWithMultipleTargets();
}
sequences[bestFrom].first = NULL;
// Find the next sequence to be processed
//
bestFrequency = -1;
bestFrom = -1;
for (i = numBlocks-1; i >= 0; i--)
{
entry = sequences[i].first;
if (entry && entry->block->getFrequency() > bestFrequency)
{
bestFrequency = entry->block->getFrequency();
bestFrom = i;
}
}
}
if (blocksWereExtended)
optimizer()->enableAllLocalOpts();
return 1; // actual cost
}
const char *
TR_ExtendBasicBlocks::optDetailString() const throw()
{
return "O^O BASIC BLOCK EXTENSION: ";
}
// void TR_BlockManipulator::markColdBlocks()
// {
// TR::Block *block = comp()->getStartTree()->getNode()->getBlock();
// for (; block;block = block->getNextBlock())
// {
// TR::TreeTop *lastNonFenceTree = block->getLastRealTreeTop();
// TR::Node *node = lastNonFenceTree->getNode();
// if (node->getOpCode().isReturn() ||
// (node->getOpCode().isTreeTop() &&
// (node->getNumChildren() > 0) &&
// (node->getFirstChild()->getOpCodeValue() == TR::athrow)))
// block->setIsCold();
// // mark the guarded virtual call blocks as being cold
// //
// if (node->isTheVirtualGuardForAGuardedInlinedCall())
// {
// TR::TreeTop *tt = node->getVirtualCallTreeForGuard();
// if (tt)
// {
// for (;
// tt->getNode()->getOpCodeValue() != TR::BBEnd;
// tt = tt->getNextRealTreeTop())
// ;
// tt->getNode()->getBlock()->setIsCold();
// }
// }
// }
// }
int32_t TR_BlockManipulator::estimatedHotness(TR::CFGEdge *edge, TR::Block *block)
{
return edge->getFrequency();
/*
int32_t hotness = unknownHotness;
if (block->isCold())
return -1;
if (edge)
hotness = edge->getHotness(comp()->getFlowGraph());
if (hotness == unknownHotness)
{
if (block->isCold())
hotness = -2;
else
{
hotness = block->getHotness(comp()->getFlowGraph());
if (hotness == unknownHotness)
hotness = block->getNestingDepth();
}
}
return hotness;
*/
}
TR::Block *TR_BlockManipulator::getBestChoiceForExtension(TR::Block *block1)
{
TR::Block *bestExtension = NULL;
int32_t numberOfRealTreesInBlock = -1;
TR::Block *fallThroughBlock = 0;
TR::TreeTop *nextTree = block1->getExit()->getNextRealTreeTop();
if (nextTree)
fallThroughBlock = nextTree->getNode()->getBlock();
if (block1->getLastRealTreeTop()->getNode()->getOpCode().isBranch() &&
block1->getLastRealTreeTop()->getNode()->isNopableInlineGuard())
return fallThroughBlock;
int32_t hotness = -3;
int32_t nestingDepth = -1;
for (auto nextEdge = block1->getSuccessors().begin(); nextEdge != block1->getSuccessors().end(); ++nextEdge)
{
TR::Block *nextBlock = toBlock((*nextEdge)->getTo());
if (!(nextBlock->getPredecessors().size() == 1))
continue; // Not a candidate for extension
int32_t nextHotness = estimatedHotness(*nextEdge, nextBlock);
if (trace())
traceMsg(comp(), " Estimating hotness for BB [%d], next BB [%d], estimated hotness %d\n", block1->getNumber(), nextBlock->getNumber(), nextHotness);
if (nextHotness > hotness)
{
bestExtension = nextBlock;
numberOfRealTreesInBlock = countNumberOfTreesInSameExtendedBlock(nextBlock);
hotness = nextHotness;
int32_t nextBlockNestingDepth = 1;
if (nextBlock->getStructureOf())
nextBlock->getStructureOf()->calculateFrequencyOfExecution(&nextBlockNestingDepth);
nestingDepth = nextBlockNestingDepth;
}
else if (hotness >= 0 && nextHotness == hotness)
{
int32_t nextBlockNestingDepth = 1;
if (nextBlock->getStructureOf())
nextBlock->getStructureOf()->calculateFrequencyOfExecution(&nextBlockNestingDepth);
int32_t nextBlockNumTrees = countNumberOfTreesInSameExtendedBlock(nextBlock);
if ((nextBlockNestingDepth > nestingDepth) ||
((nextBlockNestingDepth == nestingDepth) &&
(nextBlockNumTrees > numberOfRealTreesInBlock)))
{
bestExtension = nextBlock;
numberOfRealTreesInBlock = nextBlockNumTrees;
hotness = nextHotness;
nestingDepth = nextBlockNestingDepth;
}
else if ((nextBlockNestingDepth == nestingDepth) &&
(nextBlockNumTrees == numberOfRealTreesInBlock))
{
if (nextBlock == fallThroughBlock)
bestExtension = nextBlock;
}
}
else if (nextHotness == hotness)
{
// In case of a tie between cold blocks, favour nextBlock
// if it is the fall through block.
//
if (nextBlock == fallThroughBlock)
{
bestExtension = nextBlock;
numberOfRealTreesInBlock = countNumberOfTreesInSameExtendedBlock(nextBlock);
int32_t nextBlockNestingDepth = 1;
if (nextBlock->getStructureOf())
nextBlock->getStructureOf()->calculateFrequencyOfExecution(&nextBlockNestingDepth);
nestingDepth = nextBlockNestingDepth;
}
}
}
return bestExtension;
}
bool TR_BlockManipulator::isBestChoiceForFallThrough(TR::Block *block1, TR::Block *block2)
{
// We don't want supercold block to be fall-through block
if (block1->isSuperCold() ||
((block1->getSuccessors().size() == 1) &&
block1->getSuccessors().front()->getTo()->asBlock()->isSuperCold()))
return false;
bool bestSucc = false;
bool bestPred = false;
if (block1->getSuccessors().size() == 1)
bestSucc = true;
if (block2->getPredecessors().size() == 1)
bestPred = true;
if (bestSucc && bestPred)
return true;
// Loop back edges are usually desired to be backward branches
// into the loop entry block; the loop pre-header should fall into the
// entry. This is an exception to the usual rule where we allow the hottest
// block to fall into a successor. In this case the hottest block (block
// inside the loop that conditionally branches back to entry) branches back to
// the loop whereas the colder block falls into it
//
bool isLoopBackEdge = false;
if (comp()->getFlowGraph()->getStructure())
{
bool isLoopHdr = false;
TR_Structure *containingLoop = NULL;
TR_Structure *blockStructure2 = block2->getStructureOf();
while (blockStructure2)
{
if (blockStructure2->asRegion() && blockStructure2->asRegion()->isNaturalLoop())
{
if (blockStructure2->getNumber() == block2->getNumber())
isLoopHdr = true;
containingLoop = blockStructure2;
break;
}
blockStructure2 = blockStructure2->getParent();
}
if (isLoopHdr)
{
if (blockStructure2->asRegion()->getEntryBlock()->getStructureOf()->isEntryOfShortRunningLoop())
return false;
TR_Structure *blockStructure1 = block1->getStructureOf();
while (blockStructure1)
{
if (blockStructure1 == containingLoop)
{
isLoopBackEdge = true;