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[X86][SSE] canReduceVMulWidth - use ComputeNumSignBits/SignBitIsZero directly 

Don't reinvent the wheel for BUILD_VECTOR/ZERO_EXTEND - its only the ANY_EXTEND special case that needs handling.

llvm-svn: 343096
This commit is contained in:
Simon Pilgrim 2018-09-26 11:48:52 +00:00
parent 5d6f3d9f45
commit ebabd79f43
1 changed files with 1 additions and 17 deletions
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18
llvm/lib/Target/X86/X86ISelLowering.cpp
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@ -33967,25 +33967,9 @@ static bool canReduceVMulWidth(SDNode *N, SelectionDAG &DAG, ShrinkMode &Mode) {
else
return false;
IsPositive[i] = true;
} else if (Opd.getOpcode() == ISD::BUILD_VECTOR) {
// All the operands of BUILD_VECTOR need to be int constant.
// Find the smallest value range which all the operands belong to.
SignBits[i] = 32;
IsPositive[i] = true;
for (const SDValue &SubOp : Opd.getNode()->op_values()) {
if (SubOp.isUndef())
continue;
auto *CN = dyn_cast<ConstantSDNode>(SubOp);
if (!CN)
return false;
APInt IntVal = CN->getAPIntValue();
if (IntVal.isNegative())
IsPositive[i] = false;
SignBits[i] = std::min(SignBits[i], IntVal.getNumSignBits());
}
} else {
SignBits[i] = DAG.ComputeNumSignBits(Opd);
if (Opd.getOpcode() == ISD::ZERO_EXTEND)
if (DAG.SignBitIsZero(Opd))
IsPositive[i] = true;
}
}