maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[X86] In lowerVSELECTtoVectorShuffle, don't map undef select condition to undef in shuffle mask. 

Undef in select condition means we should pick the element from one side or the other. An undef in a shuffle mask means pick any element from either source or worse.

I suspect by the time we get here most of the undefs in a constant vector have been removed by other things, but doing this for safety.

llvm-svn: 325394
This commit is contained in:
Craig Topper 2018-02-16 21:36:29 +00:00
parent 331f97e171
commit 27b9ac2372
1 changed files with 6 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
llvm/lib/Target/X86/X86ISelLowering.cpp
View File

@ -14745,9 +14745,12 @@ static SDValue lowerVSELECTtoVectorShuffle(SDValue Op,
SmallVector<int, 32> Mask;
for (int i = 0, Size = VT.getVectorNumElements(); i < Size; ++i) {
SDValue CondElt = CondBV->getOperand(i);
Mask.push_back(
isa<ConstantSDNode>(CondElt) ? i + (isNullConstant(CondElt) ? Size : 0)
: -1);
int M = i;
// We can't map undef to undef here. They have different meanings. Treat
// as the same as zero.
if (CondElt.isUndef() || isNullConstant(CondElt))
M += Size;
Mask.push_back(M);
}
return DAG.getVectorShuffle(VT, dl, LHS, RHS, Mask);
}