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Tighten the conditions under which we do PRE, remove some unneeded code, and correct our preserved analyses list, since we

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do now change the CFG by splitting critical edges during PRE.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52631 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2008-06-23 17:49:45 +00:00
parent 2a6a645709
commit b70a571c99
1 changed files with 10 additions and 12 deletions
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22
lib/Transforms/Scalar/GVN.cpp
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@ -719,10 +719,11 @@ namespace {
// This transformation requires dominator postdominator info
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<DominatorTree>();
AU.addRequired<MemoryDependenceAnalysis>();
AU.addRequired<AliasAnalysis>();
AU.addPreserved<DominatorTree>();
AU.addPreserved<AliasAnalysis>();
AU.addPreserved<MemoryDependenceAnalysis>();
}
@ -1019,7 +1020,11 @@ bool GVN::processLoad(LoadInst *L, DenseMap<Value*, LoadInst*> &lastLoad,
}
Value* GVN::lookupNumber(BasicBlock* BB, uint32_t num) {
ValueNumberScope* locals = localAvail[BB];
DenseMap<BasicBlock*, ValueNumberScope*>::iterator I = localAvail.find(BB);
if (I == localAvail.end())
return 0;
ValueNumberScope* locals = I->second;
while (locals) {
DenseMap<uint32_t, Value*>::iterator I = locals->table.find(num);
@ -1167,9 +1172,9 @@ bool GVN::performPRE(Function& F) {
for (BasicBlock::iterator BI = CurrentBlock->begin(),
BE = CurrentBlock->end(); BI != BE; ) {
if (isa<AllocaInst>(BI) || isa<TerminatorInst>(BI) ||
isa<LoadInst>(BI) || isa<StoreInst>(BI) ||
isa<CallInst>(BI) || isa<PHINode>(BI)) {
if (isa<AllocationInst>(BI) || isa<TerminatorInst>(BI) ||
isa<PHINode>(BI) || BI->mayReadFromMemory() ||
BI->mayWriteToMemory()) {
BI++;
continue;
}
@ -1282,13 +1287,6 @@ bool GVN::performPRE(Function& F) {
Phi->addIncoming(predMap[*PI], *PI);
VN.add(Phi, valno);
// The newly created PHI completely replaces the old instruction,
// so we need to update the maps to reflect this.
DomTreeNode* DTN = getAnalysis<DominatorTree>()[CurrentBlock];
for (DomTreeNode::iterator UI = DTN->begin(), UE = DTN->end();
UI != UE; ++UI)
localAvail[(*UI)->getBlock()]->table[valno] = Phi;
localAvail[CurrentBlock]->table[valno] = Phi;
BI->replaceAllUsesWith(Phi);