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[SelectionDAG] MaskedValueIsZero - add demanded elements implementation 

Will be used in an upcoming patch but I've updated the original implementation to call this to ensure test coverage.

llvm-svn: 361738
This commit is contained in:
Simon Pilgrim 2019-05-26 18:43:44 +00:00
parent a549dd2560
commit 2916b9e28c
2 changed files with 23 additions and 4 deletions
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10
llvm/include/llvm/CodeGen/SelectionDAG.h
View File

@ -1448,8 +1448,14 @@ public:
/// Return true if 'Op & Mask' is known to be zero. We
/// use this predicate to simplify operations downstream. Op and Mask are
/// known to be the same type.
bool MaskedValueIsZero(SDValue Op, const APInt &Mask, unsigned Depth = 0)
const;
bool MaskedValueIsZero(SDValue Op, const APInt &Mask,
unsigned Depth = 0) const;
/// Return true if 'Op & Mask' is known to be zero in DemandedElts. We
/// use this predicate to simplify operations downstream. Op and Mask are
/// known to be the same type.
bool MaskedValueIsZero(SDValue Op, const APInt &Mask,
const APInt &DemandedElts, unsigned Depth = 0) const;
/// Determine which bits of Op are known to be either zero or one and return
/// them in Known. For vectors, the known bits are those that are shared by

17
llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -2207,9 +2207,22 @@ bool SelectionDAG::SignBitIsZero(SDValue Op, unsigned Depth) const {
/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
/// this predicate to simplify operations downstream. Mask is known to be zero
/// for bits that V cannot have.
bool SelectionDAG::MaskedValueIsZero(SDValue Op, const APInt &Mask,
bool SelectionDAG::MaskedValueIsZero(SDValue V, const APInt &Mask,
unsigned Depth) const {
return Mask.isSubsetOf(computeKnownBits(Op, Depth).Zero);
EVT VT = V.getValueType();
APInt DemandedElts = VT.isVector()
? APInt::getAllOnesValue(VT.getVectorNumElements())
: APInt(1, 1);
return MaskedValueIsZero(V, Mask, DemandedElts, Depth);
}
/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero in
/// DemandedElts. We use this predicate to simplify operations downstream.
/// Mask is known to be zero for bits that V cannot have.
bool SelectionDAG::MaskedValueIsZero(SDValue V, const APInt &Mask,
const APInt &DemandedElts,
unsigned Depth) const {
return Mask.isSubsetOf(computeKnownBits(V, DemandedElts, Depth).Zero);
}
/// isSplatValue - Return true if the vector V has the same value