// 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
}
static void computeInvarianceOfAllStructures(TR::Compilation *comp, TR_Structure * s)
{
TR_RegionStructure *region = s->asRegion();
if (region)
{
TR_StructureSubGraphNode *node;
TR_RegionStructure::Cursor si(*region);
for (node = si.getCurrent(); node != NULL; node = si.getNext())
computeInvarianceOfAllStructures(comp, node->getStructure());
region->resetInvariance();
if (region->isNaturalLoop() /*|| region->containsInternalCycles() */)
{
region->computeInvariantExpressions();
}
}
}
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_StructureSubGraphNode* exitNode = toStructureSubGraphNode(exitEdges.getFirst()->getFrom());
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:
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;
}
