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now that hasConstantValue defaults to only returning values that dominate

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the PHI node, this ugly code can vanish.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22672 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-08-05 01:04:30 +00:00
parent 8313a25d27
commit 68ee736694
1 changed files with 2 additions and 19 deletions
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21
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -4401,25 +4401,8 @@ static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) {
// PHINode simplification
//
Instruction *InstCombiner::visitPHINode(PHINode &PN) {
if (Value *V = PN.hasConstantValue()) {
// If V is an instruction, we have to be certain that it dominates PN.
// However, because we don't have dom info, we can't do a perfect job.
if (Instruction *I = dyn_cast<Instruction>(V)) {
// We know that the instruction dominates the PHI if there are no undef
// values coming in. If the instruction is defined in the entry block,
// and is not an invoke, we know it is ok.
if (I->getParent() != &I->getParent()->getParent()->front() ||
isa<InvokeInst>(I))
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
if (isa<UndefValue>(PN.getIncomingValue(i))) {
V = 0;
break;
}
}
if (V)
return ReplaceInstUsesWith(PN, V);
}
if (Value *V = PN.hasConstantValue())
return ReplaceInstUsesWith(PN, V);
// If the only user of this instruction is a cast instruction, and all of the
// incoming values are constants, change this PHI to merge together the casted