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OMRCfg.cpp
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OMRCfg.cpp
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/*******************************************************************************
* Copyright (c) 2000, 2019 IBM Corp. and others
*
* 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 http://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] http://openjdk.java.net/legal/assembly-exception.html
*
* 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
*******************************************************************************/
#include "infra/OMRCfg.hpp"
#include <algorithm>
#include <limits.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include "compile/Compilation.hpp"
#include "control/Options.hpp"
#include "control/Options_inlines.hpp"
#include "env/TRMemory.hpp"
#include "env/PersistentInfo.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/symbol/LabelSymbol.hpp"
#include "il/symbol/ResolvedMethodSymbol.hpp"
#include "il/TreeTop.hpp"
#include "il/TreeTop_inlines.hpp"
#include "infra/Assert.hpp"
#include "infra/Cfg.hpp"
#include "infra/deque.hpp"
#include "infra/Link.hpp"
#include "infra/List.hpp"
#include "infra/Stack.hpp"
#include "infra/CfgEdge.hpp"
#include "infra/CfgNode.hpp"
#include "optimizer/Optimizer.hpp"
#include "optimizer/Structure.hpp"
#include "optimizer/StructuralAnalysis.hpp"
#include "ras/Debug.hpp"
#ifdef __MVS__
#include <stdlib.h>
#endif
#define OPT_DETAILS "O^O LOCAL OPTS: "
TR::CFG *
OMR::CFG::self() {
return static_cast<TR::CFG*>(this);
}
TR::CFGNode *
OMR::CFG::addNode(TR::CFGNode *n, TR_RegionStructure *parent, bool isEntryInParent)
{
_nodes.add(n);
n->setNumber(allocateNodeNumber());
if (parent &&
getStructure())
{
TR::Block *block = n->asBlock();
if (block)
{
TR_BlockStructure *blockStructure = block->getStructureOf();
TR_StructureSubGraphNode *blockNode = NULL;
if (!blockStructure)
blockStructure = new (structureRegion()) TR_BlockStructure(comp(), block->getNumber(), block);
else
{
TR_StructureSubGraphNode *node;
TR_RegionStructure::Cursor si(*parent);
for (node = si.getCurrent(); node != NULL; node = si.getNext())
{
if (node->getStructure() == blockStructure)
{
blockNode = node;
break;
}
}
}
blockStructure->setNumber(n->getNumber());
if (!blockNode)
{
blockNode = new (structureRegion()) TR_StructureSubGraphNode(blockStructure);
if (!isEntryInParent)
{
parent->addSubNode(blockNode);
}
else
{
//TR_ASSERT(0, "Adding node as entry in structure\n");
setStructure(NULL);
}
}
blockNode->setNumber(n->getNumber());
}
else
TR_ASSERT(0, "Trying to add block structure without creating a block\n");
}
return n;
}
void
OMR::CFG::addEdge(TR::CFGEdge *e)
{
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
{
traceMsg(comp(),"\nAdding edge %d-->%d:\n", e->getFrom()->getNumber(), e->getTo()->getNumber());
}
_numEdges++;
// Tell the control tree to modify the structures containing this edge
//
if (getStructure() != NULL)
{
getStructure()->addEdge(e, false);
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
{
traceMsg(comp(),"\nStructures after adding edge %d-->%d:\n", e->getFrom()->getNumber(), e->getTo()->getNumber());
comp()->getDebug()->print(comp()->getOutFile(), _rootStructure, 6);
}
}
}
TR::CFGEdge *
OMR::CFG::addEdge(TR::CFGNode *f, TR::CFGNode *t, TR_AllocationKind allocKind)
{
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
{
traceMsg(comp(),"\nAdding real edge %d-->%d:\n", f->getNumber(), t->getNumber());
}
TR_ASSERT(!f->hasExceptionSuccessor(t), "adding a non exception edge when there's already an exception edge");
TR::CFGEdge * e = TR::CFGEdge::createEdge(f, t, trMemory(), allocKind);
addEdge(e);
return e;
}
void
OMR::CFG::addExceptionEdge(
TR::CFGNode *f,
TR::CFGNode *t,
TR_AllocationKind allocKind)
{
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
{
traceMsg(comp(),"\nAdding exception edge %d-->%d:\n", f->getNumber(), t->getNumber());
}
TR_ASSERT(!f->hasSuccessor(t), "adding an exception edge when there's already a non exception edge");
TR::Block * newCatchBlock = toBlock(t);
for (auto e = f->getExceptionSuccessors().begin(); e != f->getExceptionSuccessors().end(); ++e)
{
TR::Block * existingCatchBlock = toBlock((*e)->getTo());
if (newCatchBlock == existingCatchBlock) return;
// OSR exception edges are special and we do not want any 'optimization' done to them
// from the following special checks
if (newCatchBlock->isOSRCatchBlock() || existingCatchBlock->isOSRCatchBlock()) continue;
// If the existing catch block is going to be considered first and it catches everything that
// the new catch block does then the new catch block isn't reaching from the 'f' block
//
// Catch block 'A' is considered before catch block 'B' if 'A' is from a greater inline depth
// or 'A' and 'B' are from the same inline depth and 'A' handler index is less than 'B's.
//
int32_t existingDepth = existingCatchBlock->getInlineDepth();
int32_t newDepth = newCatchBlock->getInlineDepth();
if (existingDepth < newDepth ||
(existingDepth == newDepth && existingCatchBlock->getHandlerIndex() > newCatchBlock->getHandlerIndex()))
continue;
// The existing catch block is going to be considered first. Don't add an edge to the new catch
// block if the existing one catches everything that the new one catches.
//
/////void * newEC = newCatchBlock->getExceptionClass(), * existingEC = existingCatchBlock->getExceptionClass();
if (existingCatchBlock->getCatchType() == 0 ||
/////(newEC && existingEC && isInstanceOf(newEC, existingEC)) ||
(existingDepth == newDepth && existingCatchBlock->getCatchType() == newCatchBlock->getCatchType()))
{
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
{
traceMsg(comp(),"\nAddition of exception edge aborted - existing catch alredy handles this case!");
}
return;
}
}
TR::CFGEdge* e = TR::CFGEdge::createExceptionEdge(f,t, trMemory(), allocKind);
_numEdges++;
// Tell the control tree to modify the structures containing this edge
//
if (getStructure() != NULL)
{
getStructure()->addEdge(e, true);
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
{
traceMsg(comp(),"\nStructures after adding exception edge %d-->%d:\n", f->getNumber(), t->getNumber());
comp()->getDebug()->print(comp()->getOutFile(), _rootStructure, 6);
}
}
}
void
OMR::CFG::addSuccessorEdges(TR::Block * block)
{
TR::Node * node = block->getLastRealTreeTop()->getNode();
switch (node->getOpCode().getOpCodeValue())
{
case TR::table:
case TR::lookup:
case TR::trtLookup:
{
vcount_t visitCount = comp()->incVisitCount();
int32_t n = node->getCaseIndexUpperBound();
for (int32_t i = 1; i < n; ++i)
{
TR::TreeTop * target = node->getChild(i)->getBranchDestination();
TR::Block * targetBlock = target->getNode()->getBlock();
if (targetBlock->getVisitCount() != visitCount)
{
addEdge(block, targetBlock);
targetBlock->setVisitCount(visitCount);
}
}
break;
}
case TR::ificmpeq: case TR::ificmpne: case TR::ificmplt: case TR::ificmpge: case TR::ificmpgt: case TR::ificmple:
case TR::ifiucmplt: case TR::ifiucmpge: case TR::ifiucmpgt: case TR::ifiucmple:
case TR::iflcmpeq: case TR::iflcmpne: case TR::iflcmplt: case TR::iflcmpge: case TR::iflcmpgt: case TR::iflcmple:
case TR::iffcmpeq: case TR::iffcmpne: case TR::iffcmplt: case TR::iffcmpge: case TR::iffcmpgt: case TR::iffcmple:
case TR::ifdcmpeq: case TR::ifdcmpne: case TR::ifdcmplt: case TR::ifdcmpge: case TR::ifdcmpgt: case TR::ifdcmple:
case TR::ifbcmpeq: case TR::ifbcmpne: case TR::ifbcmplt: case TR::ifbcmpge: case TR::ifbcmpgt: case TR::ifbcmple:
case TR::ifscmpeq: case TR::ifscmpne: case TR::ifscmplt: case TR::ifscmpge: case TR::ifscmpgt: case TR::ifscmple:
case TR::ifsucmpne: case TR::ifsucmplt: case TR::ifsucmpge: case TR::ifsucmpgt: case TR::ifsucmple:
case TR::ifacmpeq: case TR::ifacmpne:
case TR::iffcmpequ: case TR::iffcmpneu: case TR::iffcmpltu: case TR::iffcmpgeu: case TR::iffcmpgtu: case TR::iffcmpleu:
case TR::ifdcmpequ: case TR::ifdcmpneu: case TR::ifdcmpltu: case TR::ifdcmpgeu: case TR::ifdcmpgtu: case TR::ifdcmpleu:
{
TR::Block * branchBlock = node->getBranchDestination()->getNode()->getBlock();
addEdge(block, branchBlock);
TR::Block * nextBlock = block->getExit()->getNextTreeTop()->getNode()->getBlock();
if (branchBlock != nextBlock)
addEdge(block, nextBlock);
break;
}
case TR::Goto:
addEdge(block, node->getBranchDestination()->getNode()->getBlock());
break;
case TR::ireturn: case TR::lreturn: case TR::freturn: case TR::dreturn: case TR::areturn: case TR::Return:
case TR::athrow:
addEdge(block, getEnd());
break;
case TR::Ret:
break; // pseudo node representing a ret opcode
case TR::NULLCHK:
if (node->getFirstChild()->getOpCodeValue() == TR::athrow)
addEdge(block, getEnd());
else
addEdge(block, block->getExit()->getNextTreeTop()->getNode()->getBlock());
break;
default:
addEdge(block, block->getExit()->getNextTreeTop()->getNode()->getBlock());
}
}
void
OMR::CFG::join(TR::Block * b1, TR::Block * b2)
{
if (b2) b1->getExit()->join(b2->getEntry());
self()->addSuccessorEdges(b1);
}
void
OMR::CFG::insertBefore(TR::Block * b1, TR::Block * b2)
{
self()->addNode(b1);
self()->join(b1, b2);
}
void
OMR::CFG::copyExceptionSuccessors(
TR::CFGNode *from,
TR::CFGNode *to,
bool (*predicate)(TR::CFGEdge *))
{
for (auto e1 = from->getExceptionSuccessors().begin(); e1 != from->getExceptionSuccessors().end(); ++e1)
{
if (predicate(*e1))
{
self()->addExceptionEdge(to, toBlock((*e1)->getTo()));
}
}
}
TR_Structure *
OMR::CFG::invalidateStructure()
{
setStructure(NULL);
_structureRegion.~Region();
new (&_structureRegion) TR::Region(comp()->trMemory()->heapMemoryRegion());
return getStructure();
}
TR_Structure *
OMR::CFG::setStructure(TR_Structure *p)
{
if (_rootStructure && !p)
{
dumpOptDetails(comp(), " (Invalidating structure)\n");
}
return (_rootStructure = p);
}
/**
* Default predicate for copyExceptionSuccessors.
*/
bool OMR::alwaysTrue(TR::CFGEdge * e)
{
return true;
}
TR_OrderedExceptionHandlerIterator::TR_OrderedExceptionHandlerIterator(TR::Block * tryBlock, TR::Region &workingRegion)
{
if (tryBlock->getExceptionSuccessors().empty())
_dim = 0;
else
{
int32_t handlerDim = 1, inlineDim = 1;
for (auto e = tryBlock->getExceptionSuccessors().begin(); e != tryBlock->getExceptionSuccessors().end(); ++e)
{
TR::Block * b = toBlock((*e)->getTo());
if (b->getHandlerIndex() >= handlerDim)
handlerDim = b->getHandlerIndex() + 1;
if (b->getInlineDepth() >= inlineDim)
inlineDim = b->getInlineDepth() + 1;
}
_dim = handlerDim * inlineDim;
_handlers = (TR::Block **)workingRegion.allocate(_dim*sizeof(TR::Block *));
memset(_handlers, 0, _dim*sizeof(TR::Block *));
for (auto e = tryBlock->getExceptionSuccessors().begin(); e != tryBlock->getExceptionSuccessors().end(); ++e)
{
TR::Block * b = toBlock((*e)->getTo());
TR_ASSERT((_handlers[((inlineDim - b->getInlineDepth() - 1) * handlerDim) + b->getHandlerIndex()] == NULL), "handler entry is not NULL\n");
_handlers[((inlineDim - b->getInlineDepth() - 1) * handlerDim) + b->getHandlerIndex()] = b;
}
}
}
TR::Block *
TR_OrderedExceptionHandlerIterator::getFirst()
{
_index = 0;
return getCurrent();
}
TR::Block *
TR_OrderedExceptionHandlerIterator::getNext()
{
++_index;
return getCurrent();
}
TR::Block *
TR_OrderedExceptionHandlerIterator::getCurrent()
{
TR::Block * handler = 0;
while (_index < _dim && (handler = _handlers[_index]) == 0)
++_index;
return handler;
}
TR::CFGEdge::CFGEdge(TR::CFGNode *pF, TR::CFGNode *pT)
: _pFrom(pF), _pTo(pT), _visitCount(0), _frequency(0), _id(-1)
{}
TR::CFGEdge * TR::CFGEdge::createEdge (TR::CFGNode *pF, TR::CFGNode *pT, TR_Memory* trMemory, TR_AllocationKind allocKind)
{
TR::CFGEdge * newEdge = new (trMemory, allocKind) TR::CFGEdge(pF, pT);
pF->addSuccessor(newEdge);
pT->addPredecessor(newEdge);
if (pT->getFrequency() >= 0)
newEdge->setFrequency(pT->getFrequency());
if ((pF->getFrequency() >= 0) && (pF->getFrequency() < newEdge->getFrequency()))
newEdge->setFrequency(pF->getFrequency());
return newEdge;
}
TR::CFGEdge * TR::CFGEdge::createEdge (TR::CFGNode *pF, TR::CFGNode *pT, TR::Region ®ion)
{
TR::CFGEdge * newEdge = new (region) TR::CFGEdge(pF, pT);
pF->addSuccessor(newEdge);
pT->addPredecessor(newEdge);
if (pT->getFrequency() >= 0)
newEdge->setFrequency(pT->getFrequency());
if ((pF->getFrequency() >= 0) && (pF->getFrequency() < newEdge->getFrequency()))
newEdge->setFrequency(pF->getFrequency());
return newEdge;
}
TR::CFGEdge * TR::CFGEdge::createExceptionEdge (TR::CFGNode *pF, TR::CFGNode *pT, TR_Memory* trMemory, TR_AllocationKind allocKind)
{
TR::CFGEdge * newEdge = new (trMemory, allocKind) TR::CFGEdge(pF, pT);
pF->addExceptionSuccessor(newEdge);
pT->addExceptionPredecessor(newEdge);
return newEdge;
}
TR::CFGEdge * TR::CFGEdge::createExceptionEdge (TR::CFGNode *pF, TR::CFGNode *pT, TR::Region ®ion)
{
TR::CFGEdge * newEdge = new (region) TR::CFGEdge(pF, pT);
pF->addExceptionSuccessor(newEdge);
pT->addExceptionPredecessor(newEdge);
return newEdge;
}
void TR::CFGEdge::setFrom(TR::CFGNode *pF)
{
_pFrom = pF;
pF->addSuccessor(this);
}
void TR::CFGEdge::setTo(TR::CFGNode *pT)
{
_pTo = pT;
pT->addPredecessor(this);
}
void TR::CFGEdge::setExceptionFrom(TR::CFGNode *pF)
{
_pFrom = pF;
pF->addExceptionSuccessor(this);
}
void TR::CFGEdge::setExceptionTo(TR::CFGNode *pT)
{
_pTo = pT;
pT->addExceptionPredecessor(this);
}
void TR::CFGEdge::setFromTo(TR::CFGNode *pF, TR::CFGNode *pT)
{
setFrom(pF);
setTo(pT);
}
void TR::CFGEdge::setExceptionFromTo(TR::CFGNode *pF, TR::CFGNode *pT)
{
_pFrom = pF;
_pTo = pT;
pF->addExceptionSuccessor(this);
pT->addExceptionPredecessor(this);
}
static int32_t getTotalEdgesFrequency(TR::CFGEdgeList& edgesList)
{
int32_t totalFreq = 0;
for (auto edge = edgesList.begin(); edge != edgesList.end(); ++edge)
totalFreq += (*edge)->getFrequency();
return totalFreq;
}
bool OMR::CFG::updateBlockFrequency(TR::Block *block, int32_t newFreq)
{
int16_t oldFreq = block->getFrequency();
if (newFreq != oldFreq && newFreq >= 0)
{
if (comp()->getOption(TR_TraceBFGeneration))
traceMsg(comp(), "updated block %d freq from %d to %d\n", block->getNumber(), oldFreq, newFreq);
block->setFrequency(newFreq);
return true;
}
else
return false;
}
void OMR::CFG::updateBlockFrequencyFromEdges(TR::Block *block)
{
int32_t totalPredFreq = getTotalEdgesFrequency(block->getPredecessors()) + getTotalEdgesFrequency(block->getExceptionPredecessors());
int32_t totalSuccFreq = getTotalEdgesFrequency(block->getSuccessors()) + getTotalEdgesFrequency(block->getExceptionSuccessors());
int32_t maxNewFreq = std::min(totalPredFreq, totalSuccFreq);
// currently only lower frequency
if (maxNewFreq < block->getFrequency())
updateBlockFrequency(block, maxNewFreq);
}
TR::CFGNode::CFGNode(TR_Memory * m)
: _nodeNumber(-1),
_visitCount(0),
_frequency(-1),
_forwardTraversalIndex(-1),
_backwardTraversalIndex(-1),
_region(m->heapMemoryRegion()),
_successors(m->heapMemoryRegion()),
_predecessors(m->heapMemoryRegion()),
_exceptionSuccessors(m->heapMemoryRegion()),
_exceptionPredecessors(m->heapMemoryRegion())
{
}
TR::CFGNode::CFGNode(int32_t n, TR_Memory * m)
: _nodeNumber(n),
_visitCount(0),
_frequency(-1),
_forwardTraversalIndex(-1),
_backwardTraversalIndex(-1),
_region(m->heapMemoryRegion()),
_successors(m->heapMemoryRegion()),
_predecessors(m->heapMemoryRegion()),
_exceptionSuccessors(m->heapMemoryRegion()),
_exceptionPredecessors(m->heapMemoryRegion())
{
}
TR::CFGNode::CFGNode(TR::Region ®ion)
: _nodeNumber(-1),
_visitCount(0),
_frequency(-1),
_forwardTraversalIndex(-1),
_backwardTraversalIndex(-1),
_region(region),
_successors(region),
_predecessors(region),
_exceptionSuccessors(region),
_exceptionPredecessors(region)
{
}
TR::CFGNode::CFGNode(int32_t n, TR::Region ®ion)
: _nodeNumber(n),
_visitCount(0),
_frequency(-1),
_forwardTraversalIndex(-1),
_backwardTraversalIndex(-1),
_region(region),
_successors(region),
_predecessors(region),
_exceptionSuccessors(region),
_exceptionPredecessors(region)
{
}
// This method needs to be non-inlined so that the home for TR::CFGNode's vft is
// established.
//
void TR::CFGNode::removeFromCFG(TR::Compilation *c)
{
}
TR::TreeTop * OMR::CFG::findLastTreeTop()
{
TR::Block *cursorBlock = getStart()->getSuccessors().front()->getTo()->asBlock();
TR::Block *prevCursorBlock = NULL;
while (cursorBlock)
{
prevCursorBlock = cursorBlock;
cursorBlock = cursorBlock->getNextBlock();
}
if (prevCursorBlock)
return prevCursorBlock->getExit();
return NULL;
}
TR::CFGEdge *TR::CFGNode::getEdge(TR::CFGNode *n)
{
TR_SuccessorIterator ei(this);
for (TR::CFGEdge * edge = ei.getFirst(); edge != NULL; edge = ei.getNext())
{
if (edge->getTo() == n)
return edge;
}
return NULL;
}
template <typename FUNC>
TR::CFGEdge * TR::CFGNode::getEdgeMatchingNodeInAList (TR::CFGNode * n, TR::CFGEdgeList& list, FUNC blockGetter)
{
for (auto edge = list.begin(); edge != list.end(); ++edge)
{
if (blockGetter(*edge) == n)
return *edge;
}
return NULL;
}
TR::CFGEdge * TR::CFGNode::getSuccessorEdge(TR::CFGNode * n)
{
return getEdgeMatchingNodeInAList(n, getSuccessors(), toBlockGetter);
}
TR::CFGEdge * TR::CFGNode::getExceptionSuccessorEdge(TR::CFGNode * n)
{
return getEdgeMatchingNodeInAList(n, getExceptionSuccessors(), toBlockGetter);
}
TR::CFGEdge * TR::CFGNode::getPredecessorEdge(TR::CFGNode * n)
{
return getEdgeMatchingNodeInAList(n, getPredecessors(), fromBlockGetter);
}
TR::CFGEdge * TR::CFGNode::getExceptionPredecessorEdge(TR::CFGNode * n)
{
return getEdgeMatchingNodeInAList(n, getExceptionPredecessors(), fromBlockGetter);
}
bool TR::CFGNode::hasSuccessor(TR::CFGNode * n)
{
return (bool)getSuccessorEdge(n);
}
bool TR::CFGNode::hasExceptionSuccessor(TR::CFGNode * n)
{
return (bool)getExceptionSuccessorEdge(n);
}
bool TR::CFGNode::hasPredecessor(TR::CFGNode * n)
{
return (bool)getPredecessorEdge(n);
}
bool TR::CFGNode::hasExceptionPredecessor(TR::CFGNode * n)
{
return (bool)getExceptionPredecessorEdge(n);
}
TR::CFGNode *OMR::CFG::removeNode(TR::CFGNode *node)
{
if (node->nodeIsRemoved())
return 0;
_nodes.remove(node);
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
traceMsg(comp(),"\nRemoving node %d\n", node->getNumber());
node->removeFromCFG(comp());
// Remove the exception successors first, so that try/finally structures get
// cleaned up in the right order. Nobody else cares about the order.
//
ListElement<TR::CFGEdge> *out;
while (!node->getExceptionSuccessors().empty())
removeEdge(node->getExceptionSuccessors().front());
while (!node->getSuccessors().empty())
removeEdge(node->getSuccessors().front());
// All predecessors must have been removed otherwise the CFG will be inconsistent.
//
TR_ASSERT(node->getPredecessors().empty(),
"CFG, removing a node that still has predecessors");
TR_ASSERT(node->getExceptionPredecessors().empty(),
"CFG, removing a node that still has predecessors");
node->removeNode();
return node;
}
enum OrphanType
{
IsParented = 0,
IsOrphanedNode,
IsOrphanedRegion
};
// test if 'to' is an unreachable orphan
//
static OrphanType unreachableOrphan(TR::CFG *cfg, TR::CFGNode *from, TR::CFGNode *to)
{
// If the "to" node is orphaned by removing this edge, remove it from the
// CFG as long as it is not the exit node - it is valid for the exit node
// to be unreachable.
//
if ((to->getPredecessors().empty() && to->getExceptionPredecessors().empty() &&
to != cfg->getEnd()) ||
(to->getExceptionPredecessors().empty() && (to->getPredecessors().size() == 1) &&
to->getPredecessors().front()->getFrom() == to) ||
(to->getPredecessors().empty() && (to->getExceptionPredecessors().size() == 1) &&
to->getExceptionPredecessors().front()->getFrom() == to))
{
return IsOrphanedNode;
}
// If we have structure, and 'to' is the entry node of a cyclic region
// and as a result of removing this edge we have made 'to' unreachable, except
// from backedges originating from within 'to' then recognize 'to' to be orphaned
//
if (cfg->getStructure())
{
TR_RegionStructure *parent = from->asBlock()->getStructureOf()->findCommonParent(to->asBlock()->getStructureOf(), cfg);
TR_StructureSubGraphNode *toSubNode = parent->findSubNodeInRegion(to->getNumber());
TR_ASSERT(toSubNode, "cannot have cfg edge a->b in region p where b is not a direct subnode of p");
TR_RegionStructure *toRegion = toSubNode->getStructure()->asRegion();
if (toRegion)
{
bool onlyBackEdges = true;
TR_PredecessorIterator pit(to);
TR::CFGEdge *edge;
for (edge = pit.getFirst(); edge; edge = pit.getNext())
{
if (!toRegion->contains(edge->getFrom()->asBlock()->getStructureOf()) &&
(edge->getFrom() != from))
{
onlyBackEdges = false;
break;
}
}
if (onlyBackEdges)
return IsOrphanedRegion;
}
}
return IsParented;
}
/*
This Function looks for an edge in the successor/predecessor OR
exceptionSuccessor/exceptionPredecessor Lists from the 'from' and 'to' Nodes of
the edge If the edge is not found in either combination, we return false
*/
bool OMR::CFG::removeEdge(TR::CFGEdge *edge)
{
bool blocksWereRemoved = false;
TR::CFGNode *from = edge->getFrom();
TR::CFGNode *to = edge->getTo();
TR::StackMemoryRegion stackMemoryRegion(*trMemory());
_mightHaveUnreachableBlocks = true;
bool found = false;
if (std::find(from->getSuccessors().begin(), from->getSuccessors().end(), edge) != from->getSuccessors().end()) {
found = true;
from->getSuccessors().remove(edge);
}
else if (std::find(from->getExceptionSuccessors().begin(), from->getExceptionSuccessors().end(), edge) != from->getExceptionSuccessors().end()) {
found = true;
from->getExceptionSuccessors().remove(edge);
}
if (std::find(to->getPredecessors().begin(), to->getPredecessors().end(), edge) != to->getPredecessors().end()) {
found = true;
to->getPredecessors().remove(edge);
}
else if (std::find(to->getExceptionPredecessors().begin(), to->getExceptionPredecessors().end(), edge) != to->getExceptionPredecessors().end()) {
found = true;
to->getExceptionPredecessors().remove(edge);
}
if (!found)
return false;
_numEdges--;
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
traceMsg(comp(), "\nRemoving edge %d-->%d (depth %d):\n", from->getNumber(), to->getNumber(), _removeEdgeNestingDepth);
TR_ScratchList<TR::CFGNode> nodesToBeRemoved(trMemory());
bool doWalk = false;
TR_BitVector *blocksVisited = NULL;
OrphanType orphan = unreachableOrphan(self(), from, to);
if (orphan != IsParented)
{
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
{
traceMsg(comp(),"\nblock_%d is an orphan now with type=%d:\n", to->getNumber(), orphan);
}
{
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
traceMsg(comp(), "\nAdding node %d to nodesToBeRemoved from %d\n", to->getNumber(), from->getNumber());
nodesToBeRemoved.add(to);
blocksVisited = new (trStackMemory()) TR_BitVector(getNextNodeNumber(), trMemory(), stackAlloc);
blocksWereRemoved = true;
doWalk = true;
}
}
// Tell the control tree to modify the structures containing this edge
//
if (getStructure())
{
TR_Structure *fromStruct = toBlock(from)->getStructureOf();
TR_Structure *toStruct = toBlock(to)->getStructureOf();
if (fromStruct && toStruct)
{
toStruct->removeEdge(fromStruct, toStruct);
}
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
{
traceMsg(comp(),"\nStructures changed after removing edge %d-->%d:\n", from->getNumber(), to->getNumber());
}
}
if (doWalk)
{
TR_Queue<TR::CFGNode> nodeq(trMemory());
nodeq.enqueue(to);
blocksVisited->empty();
do
{
from = nodeq.dequeue();
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
traceMsg(comp(), "\ndo walk for node %d\n", from->getNumber());
if (blocksVisited->get(from->getNumber()))
continue;
// if the node is already removed, donot process
//
if(from->nodeIsRemoved())
continue;
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
traceMsg(comp(), "Processing unreachable node %d\n", from->getNumber());
blocksVisited->set(from->getNumber());
TR_SuccessorIterator edgesIt(from);
for (TR::CFGEdge * e = edgesIt.getFirst(); e; e = edgesIt.getNext())
{
to = e->getTo();
_numEdges--;
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
traceMsg(comp(), "\n2Removing edge %d-->%d (depth %d):\n", from->getNumber(), to->getNumber(), _removeEdgeNestingDepth);
if (std::find(from->getSuccessors().begin(), from->getSuccessors().end(), e) != from->getSuccessors().end())
from->getSuccessors().remove(e);
else
from->getExceptionSuccessors().remove(e);
if (std::find(to->getPredecessors().begin(), to->getPredecessors().end(), e) != to->getPredecessors().end())
to->getPredecessors().remove(e);
else
to->getExceptionPredecessors().remove(e);
// break cycles by not adding 'to' that is
// already in the removed list
//
orphan = unreachableOrphan(self(), from, to);
if (orphan != IsParented &&
!blocksVisited->get(to->getNumber()) &&
!to->nodeIsRemoved())
{
{
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
traceMsg(comp(), "\nAdding node %d to nodesToBeRemoved from %d\n", to->getNumber(), from->getNumber());
if (orphan == IsOrphanedNode)
nodesToBeRemoved.add(to);
blocksWereRemoved = true;
nodeq.enqueue(to);
}
}
// Tell the control tree to modify the structures containing this edge
//
if (getStructure())
{
TR_Structure *fromStruct = toBlock(from)->getStructureOf();
TR_Structure *toStruct = toBlock(to)->getStructureOf();
if (fromStruct && toStruct)
toStruct->removeEdge(fromStruct, toStruct);
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
{
traceMsg(comp(),"\nStructure changed after removing edge %d-->%d:\n", from->getNumber(), to->getNumber());
///comp()->getDebug()->print(comp()->getOutFile(), getStructure(), 6);
}
}
}
} while (!nodeq.isEmpty());
// finally remove all the unreachable nodes
//
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
traceMsg(comp(),"\nNow actually removing nodes\n");
ListIterator<TR::CFGNode> nodesIt(&nodesToBeRemoved);
for (TR::CFGNode *n = nodesIt.getFirst(); n; n = nodesIt.getNext())
{
{
if (_nodes.remove(n))
{
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
traceMsg(comp(),"\nRemoved node %d\n", n->getNumber());
n->removeFromCFG(comp());
n->removeNode();
}
}
}
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
traceMsg(comp(), "\n_doesHaveUnreachableBlocks %d\n", _doesHaveUnreachableBlocks);
if (!_ignoreUnreachableBlocks && _doesHaveUnreachableBlocks)
{
removeUnreachableBlocks();
blocksWereRemoved = true;
}
}
return blocksWereRemoved;
}
bool OMR::CFG::removeEdge(TR::CFGEdge *edge, bool recursiveImpl)
{
TR::CFGNode *from = edge->getFrom();
TR::CFGNode *to = edge->getTo();
if (comp()->getOption(TR_TraceAddAndRemoveEdge))
{
traceMsg(comp(), "\nRemoving edge %d-->%d (depth %d):\n", from->getNumber(), to->getNumber(), _removeEdgeNestingDepth);
}
// Keep track of recursion level for this method.
//
++_removeEdgeNestingDepth;
// FIXME:
// due to a stack overflow error in JarTester. removeEdge
// went into a very deep recursion (159 deep) in one of the
// methods in JarTester trying to remove a large unreachable
// portion of the method. abandoning the compile at this stage
// until the non-recursive implementation above becomes active
//
if (_removeEdgeNestingDepth >
(comp()->getOption(TR_ProcessHugeMethods) ?
(MAX_REMOVE_EDGE_NESTING_DEPTH * 2) : MAX_REMOVE_EDGE_NESTING_DEPTH))
{
comp()->failCompilation<TR::ExcessiveComplexity>("Exceeded removeEdge nesting depth");
}
_numEdges--;
_mightHaveUnreachableBlocks = true;
if (std::find(from->getSuccessors().begin(), from->getSuccessors().end(), edge) != from->getSuccessors().end())