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LoopSimplify::FindPHIToPartitionLoops()

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Use ETForest instead of DominatorSet.

llvm-svn: 35221
This commit is contained in:
Devang Patel 2007-03-20 20:18:12 +00:00
parent 632ac0e289
commit 18146cf2a2
2 changed files with 25 additions and 4 deletions
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10
lib/Transforms/Utils/LoopSimplify.cpp
View File

@ -66,6 +66,7 @@ namespace {
AU.addRequired<LoopInfo>();
AU.addRequired<DominatorSet>();
AU.addRequired<DominatorTree>();
AU.addRequired<ETForest>();
AU.addPreserved<LoopInfo>();
AU.addPreserved<DominatorSet>();
@ -417,13 +418,13 @@ static void AddBlockAndPredsToSet(BasicBlock *BB, BasicBlock *StopBlock,
/// FindPHIToPartitionLoops - The first part of loop-nestification is to find a
/// PHI node that tells us how to partition the loops.
static PHINode *FindPHIToPartitionLoops(Loop *L, DominatorSet &DS,
AliasAnalysis *AA) {
static PHINode *FindPHIToPartitionLoops(Loop *L, ETForest *EF,
AliasAnalysis *AA) {
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ) {
PHINode *PN = cast<PHINode>(I);
++I;
if (Value *V = PN->hasConstantValue())
if (!isa<Instruction>(V) || DS.dominates(cast<Instruction>(V), PN)) {
if (!isa<Instruction>(V) || EF->dominates(cast<Instruction>(V), PN)) {
// This is a degenerate PHI already, don't modify it!
PN->replaceAllUsesWith(V);
if (AA) AA->deleteValue(PN);
@ -497,7 +498,8 @@ void LoopSimplify::PlaceSplitBlockCarefully(BasicBlock *NewBB,
/// created.
///
Loop *LoopSimplify::SeparateNestedLoop(Loop *L) {
PHINode *PN = FindPHIToPartitionLoops(L, getAnalysis<DominatorSet>(), AA);
ETForest *EF = getAnalysisToUpdate<ETForest>();
PHINode *PN = FindPHIToPartitionLoops(L, EF, AA);
if (PN == 0) return 0; // No known way to partition.
// Pull out all predecessors that have varying values in the loop. This

19
lib/VMCore/Dominators.cpp
View File

@ -883,6 +883,25 @@ void ETForestBase::updateDFSNumbers()
DFSInfoValid = true;
}
// dominates - Return true if A dominates B. THis performs the
// special checks necessary if A and B are in the same basic block.
bool ETForestBase::dominates(Instruction *A, Instruction *B) {
BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
if (BBA != BBB) return dominates(BBA, BBB);
// Loop through the basic block until we find A or B.
BasicBlock::iterator I = BBA->begin();
for (; &*I != A && &*I != B; ++I) /*empty*/;
if(!IsPostDominators) {
// A dominates B if it is found first in the basic block.
return &*I == A;
} else {
// A post-dominates B if B is found first in the basic block.
return &*I == B;
}
}
ETNode *ETForest::getNodeForBlock(BasicBlock *BB) {
ETNode *&BBNode = Nodes[BB];
if (BBNode) return BBNode;