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In SimplifyDemandedUseBits, use computeKnownBits directly to handle Constants 

Currently we don't explicitly process ConstantDataSequential, ConstantAggregateZero, or ConstantVector, or Undef before applying the Depth limit. Instead they occur after the depth check in the non-instruction path.

For the constant types that we do handle, the code is replicated from computeKnownBits.

This patch fixes the missing constant handling and the reduces the amount of code by just using computeKnownBits directly for any type of Constant.

Differential Revision: https://reviews.llvm.org/D32123

llvm-svn: 300849
This commit is contained in:
Craig Topper 2017-04-20 16:14:58 +00:00
parent 7500b0ece8
commit 83dc1c60aa
1 changed files with 4 additions and 15 deletions
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19
llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
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@ -117,27 +117,16 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
KnownOne.getBitWidth() == BitWidth &&
"Value *V, DemandedMask, KnownZero and KnownOne "
"must have same BitWidth");
const APInt *C;
if (match(V, m_APInt(C))) {
// We know all of the bits for a scalar constant or a splat vector constant!
KnownOne = *C;
KnownZero = ~KnownOne;
return nullptr;
}
if (isa<ConstantPointerNull>(V)) {
// We know all of the bits for a constant!
KnownOne.clearAllBits();
KnownZero.setAllBits();
if (isa<Constant>(V)) {
computeKnownBits(V, KnownZero, KnownOne, Depth, CxtI);
return nullptr;
}
KnownZero.clearAllBits();
KnownOne.clearAllBits();
if (DemandedMask == 0) { // Not demanding any bits from V.
if (isa<UndefValue>(V))
return nullptr;
if (DemandedMask == 0) // Not demanding any bits from V.
return UndefValue::get(VTy);
}
if (Depth == 6) // Limit search depth.
return nullptr;