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hasConstantValue will soon return instructions that don't dominate the PHI node,

Browse Source 
so prepare for this.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17095 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2004-10-17 21:22:38 +00:00
parent 665825e58e
commit c30bda7540
2 changed files with 39 additions and 20 deletions
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37
lib/Transforms/Utils/LoopSimplify.cpp
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@ -250,8 +250,11 @@ BasicBlock *LoopSimplify::SplitBlockPredecessors(BasicBlock *BB,
// Can we eliminate this phi node now?
if (Value *V = hasConstantValue(PN)) {
PN->replaceAllUsesWith(V);
BB->getInstList().erase(PN);
if (!isa<Instruction>(V) ||
getAnalysis<DominatorSet>().dominates(cast<Instruction>(V), PN)) {
PN->replaceAllUsesWith(V);
BB->getInstList().erase(PN);
}
}
}
@ -426,22 +429,24 @@ 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) {
static PHINode *FindPHIToPartitionLoops(Loop *L, DominatorSet &DS) {
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ) {
PHINode *PN = cast<PHINode>(I);
++I;
if (Value *V = hasConstantValue(PN)) {
// This is a degenerate PHI already, don't modify it!
PN->replaceAllUsesWith(V);
PN->getParent()->getInstList().erase(PN);
} else {
// Scan this PHI node looking for a use of the PHI node by itself.
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingValue(i) == PN &&
L->contains(PN->getIncomingBlock(i)))
// We found something tasty to remove.
return PN;
}
if (Value *V = hasConstantValue(PN))
if (!isa<Instruction>(V) || DS.dominates(cast<Instruction>(V), PN)) {
// This is a degenerate PHI already, don't modify it!
PN->replaceAllUsesWith(V);
PN->getParent()->getInstList().erase(PN);
continue;
}
// Scan this PHI node looking for a use of the PHI node by itself.
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (PN->getIncomingValue(i) == PN &&
L->contains(PN->getIncomingBlock(i)))
// We found something tasty to remove.
return PN;
}
return 0;
}
@ -464,7 +469,7 @@ static PHINode *FindPHIToPartitionLoops(Loop *L) {
/// created.
///
Loop *LoopSimplify::SeparateNestedLoop(Loop *L) {
PHINode *PN = FindPHIToPartitionLoops(L);
PHINode *PN = FindPHIToPartitionLoops(L, getAnalysis<DominatorSet>());
if (PN == 0) return 0; // No known way to partition.
// Pull out all predecessors that have varying values in the loop. This