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[X86][SSE] An empty target shuffle mask is always a failure. 

As discussed on D15378, move the mask.empty() tests to after the switch statement and consider any shuffle decode where the extracted target shuffle mask is empty as a failure.

llvm-svn: 256921
This commit is contained in:
Simon Pilgrim 2016-01-06 08:59:32 +00:00
parent 0810739d4c
commit eaabd64a11
1 changed files with 4 additions and 7 deletions
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11
llvm/lib/Target/X86/X86ISelLowering.cpp
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@ -4853,8 +4853,6 @@ static bool getTargetShuffleMask(SDNode *N, MVT VT,
if (auto *C = dyn_cast<Constant>(MaskCP->getConstVal())) {
DecodePSHUFBMask(C, Mask);
if (Mask.empty())
return false;
break;
}
@ -4872,7 +4870,6 @@ static bool getTargetShuffleMask(SDNode *N, MVT VT,
case X86ISD::VPERM2X128:
ImmN = N->getOperand(N->getNumOperands()-1);
DecodeVPERM2X128Mask(VT, cast<ConstantSDNode>(ImmN)->getZExtValue(), Mask);
if (Mask.empty()) return false;
// Mask only contains negative index if an element is zero.
if (std::any_of(Mask.begin(), Mask.end(),
[](int M){ return M == SM_SentinelZero; }))
@ -4950,8 +4947,6 @@ static bool getTargetShuffleMask(SDNode *N, MVT VT,
if (auto *C = dyn_cast<Constant>(MaskCP->getConstVal())) {
DecodeVPERMVMask(C, VT, Mask);
if (Mask.empty())
return false;
break;
}
return false;
@ -5002,8 +4997,6 @@ static bool getTargetShuffleMask(SDNode *N, MVT VT,
if (auto *C = dyn_cast<Constant>(MaskCP->getConstVal())) {
DecodeVPERMV3Mask(C, VT, Mask);
if (Mask.empty())
return false;
break;
}
return false;
@ -5011,6 +5004,10 @@ static bool getTargetShuffleMask(SDNode *N, MVT VT,
default: llvm_unreachable("unknown target shuffle node");
}
// Empty mask indicates the decode failed.
if (Mask.empty())
return false;
// If we have a fake unary shuffle, the shuffle mask is spread across two
// inputs that are actually the same node. Re-map the mask to always point
// into the first input.