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Make GVN more memory efficient, particularly on code that contains a large number of

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allocations, which GVN can't optimize anyways.

llvm-svn: 49329
This commit is contained in:
Owen Anderson 2008-04-07 09:59:07 +00:00
parent 93e8f5fbc3
commit 93ab00f1d9
2 changed files with 19 additions and 1 deletions
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4
include/llvm/Analysis/Dominators.h
View File

@ -103,6 +103,10 @@ public:
return C;
}
size_t getNumChildren() const {
return Children.size();
}
void setIDom(DomTreeNodeBase<NodeT> *NewIDom) {
assert(IDom && "No immediate dominator?");
if (IDom != NewIDom) {

16
lib/Transforms/Scalar/GVN.cpp
View File

@ -1593,6 +1593,11 @@ bool GVN::processInstruction(Instruction *I, ValueNumberedSet &currAvail,
if (StoreInst *SI = dyn_cast<StoreInst>(I))
return processStore(SI, toErase);
// Allocations are always uniquely numbered, so we can save time and memory
// by fast failing them.
if (isa<AllocationInst>(I))
return false;
if (MemCpyInst* M = dyn_cast<MemCpyInst>(I)) {
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
@ -1692,6 +1697,7 @@ bool GVN::iterateOnFunction(Function &F) {
SmallVector<Instruction*, 8> toErase;
DenseMap<Value*, LoadInst*> lastSeenLoad;
DenseMap<DomTreeNode*, size_t> numChildrenVisited;
// Top-down walk of the dominator tree
for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
@ -1704,9 +1710,17 @@ bool GVN::iterateOnFunction(Function &F) {
BasicBlock* BB = DI->getBlock();
// A block inherits AVAIL_OUT from its dominator
if (DI->getIDom() != 0)
if (DI->getIDom() != 0) {
currAvail = availableOut[DI->getIDom()->getBlock()];
numChildrenVisited[DI->getIDom()]++;
if (numChildrenVisited[DI->getIDom()] == DI->getIDom()->getNumChildren()) {
availableOut.erase(DI->getIDom()->getBlock());
numChildrenVisited.erase(DI->getIDom());
}
}
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
BI != BE;) {
changed_function |= processInstruction(BI, currAvail,