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[X86] Pull out target constant splat helper function. NFCI. 

The code in LowerScalarImmediateShift is just a more powerful version of ISD::isConstantSplatVector.

llvm-svn: 344451
This commit is contained in:
Simon Pilgrim 2018-10-13 14:28:40 +00:00
parent 10434cbae1
commit a03379527a
1 changed files with 27 additions and 17 deletions
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44
llvm/lib/Target/X86/X86ISelLowering.cpp
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@ -5830,6 +5830,30 @@ static bool getTargetConstantBitsFromNode(SDValue Op, unsigned EltSizeInBits,
return false;
}
static bool isConstantSplat(SDValue Op, APInt &SplatVal) {
APInt UndefElts;
SmallVector<APInt, 16> EltBits;
if (getTargetConstantBitsFromNode(Op, Op.getScalarValueSizeInBits(),
UndefElts, EltBits, true, false)) {
int SplatIndex = -1;
for (int i = 0, e = EltBits.size(); i != e; ++i) {
if (UndefElts[i])
continue;
if (0 <= SplatIndex && EltBits[i] != EltBits[SplatIndex]) {
SplatIndex = -1;
break;
}
SplatIndex = i;
}
if (0 <= SplatIndex) {
SplatVal = EltBits[SplatIndex];
return true;
}
}
return false;
}
static bool getTargetShuffleMaskIndices(SDValue MaskNode,
unsigned MaskEltSizeInBits,
SmallVectorImpl<uint64_t> &RawMask) {
@ -23600,7 +23624,6 @@ static SDValue LowerScalarImmediateShift(SDValue Op, SelectionDAG &DAG,
SDLoc dl(Op);
SDValue R = Op.getOperand(0);
SDValue Amt = Op.getOperand(1);
unsigned EltSizeInBits = VT.getScalarSizeInBits();
unsigned X86Opc = getTargetVShiftUniformOpcode(Op.getOpcode(), false);
auto ArithmeticShiftRight64 = [&](uint64_t ShiftAmt) {
@ -23644,24 +23667,11 @@ static SDValue LowerScalarImmediateShift(SDValue Op, SelectionDAG &DAG,
};
// Optimize shl/srl/sra with constant shift amount.
APInt UndefElts;
SmallVector<APInt, 8> EltBits;
if (!getTargetConstantBitsFromNode(Amt, EltSizeInBits, UndefElts, EltBits,
true, false))
APInt APIntShiftAmt;
if (!isConstantSplat(Amt, APIntShiftAmt))
return SDValue();
uint64_t ShiftAmt = APIntShiftAmt.getZExtValue();
int SplatIndex = -1;
for (int i = 0, e = VT.getVectorNumElements(); i != e; ++i) {
if (UndefElts[i])
continue;
if (0 <= SplatIndex && EltBits[i] != EltBits[SplatIndex])
return SDValue();
SplatIndex = i;
}
if (SplatIndex < 0)
return SDValue();
uint64_t ShiftAmt = EltBits[SplatIndex].getZExtValue();
if (SupportedVectorShiftWithImm(VT, Subtarget, Op.getOpcode()))
return getTargetVShiftByConstNode(X86Opc, dl, VT, R, ShiftAmt, DAG);