diff options
Diffstat (limited to 'llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp b/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp index d6f23b6..c1fb8b6 100644 --- a/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp +++ b/llvm/lib/CodeGen/GlobalISel/GISelValueTracking.cpp @@ -643,6 +643,38 @@ void GISelValueTracking::computeKnownBitsImpl(Register R, KnownBits &Known, Known.Zero.setBitsFrom(LowBits); break; } + case TargetOpcode::G_EXTRACT_VECTOR_ELT: { + GExtractVectorElement &Extract = cast<GExtractVectorElement>(MI); + Register InVec = Extract.getVectorReg(); + Register EltNo = Extract.getIndexReg(); + + auto ConstEltNo = getIConstantVRegVal(EltNo, MRI); + + LLT VecVT = MRI.getType(InVec); + // computeKnownBits not yet implemented for scalable vectors. + if (VecVT.isScalableVector()) + break; + + const unsigned EltBitWidth = VecVT.getScalarSizeInBits(); + const unsigned NumSrcElts = VecVT.getNumElements(); + // A return type different from the vector's element type may lead to + // issues with pattern selection. Bail out to avoid that. + if (BitWidth > EltBitWidth) + break; + + Known.Zero.setAllBits(); + Known.One.setAllBits(); + + // If we know the element index, just demand that vector element, else for + // an unknown element index, ignore DemandedElts and demand them all. + APInt DemandedSrcElts = APInt::getAllOnes(NumSrcElts); + if (ConstEltNo && ConstEltNo->ult(NumSrcElts)) + DemandedSrcElts = + APInt::getOneBitSet(NumSrcElts, ConstEltNo->getZExtValue()); + + computeKnownBitsImpl(InVec, Known, DemandedSrcElts, Depth + 1); + break; + } case TargetOpcode::G_SHUFFLE_VECTOR: { APInt DemandedLHS, DemandedRHS; // Collect the known bits that are shared by every vector element referenced |