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

[DAGCombine] Add SCALAR_TO_VECTOR undef handling to simplifyShuffleMask. 

This allows us to simplify later visitVECTOR_SHUFFLE optimizations such as combineShuffleOfScalars.

Noticed whilst working on D38696

llvm-svn: 316017
This commit is contained in:
Simon Pilgrim 2017-10-17 18:14:48 +00:00
parent 9e5751894d
commit 654bbb3b05
1 changed files with 6 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -15350,6 +15350,8 @@ static SDValue simplifyShuffleMask(ShuffleVectorSDNode *SVN, SDValue N0,
// TODO - handle more cases as required.
if (V.getOpcode() == ISD::BUILD_VECTOR)
return V.getOperand(Idx).isUndef();
if (V.getOpcode() == ISD::SCALAR_TO_VECTOR)
return (Idx != 0) || V.getOperand(0).isUndef();
return false;
};
@ -15463,6 +15465,7 @@ static SDValue combineShuffleOfScalars(ShuffleVectorSDNode *SVN,
if (!N0->hasOneUse() || !N1->hasOneUse())
return SDValue();
// If only one of N1,N2 is constant, bail out if it is not ALL_ZEROS as
// discussed above.
if (!N1.isUndef()) {
@ -15484,8 +15487,8 @@ static SDValue combineShuffleOfScalars(ShuffleVectorSDNode *SVN,
if (S.getOpcode() == ISD::BUILD_VECTOR) {
Op = S.getOperand(Idx);
} else if (S.getOpcode() == ISD::SCALAR_TO_VECTOR) {
if (Idx == 0)
Op = S.getOperand(0);
assert(Idx == 0 && "Unexpected SCALAR_TO_VECTOR operand index.");
Op = S.getOperand(0);
} else {
// Operand can't be combined - bail out.
return SDValue();
@ -15501,6 +15504,7 @@ static SDValue combineShuffleOfScalars(ShuffleVectorSDNode *SVN,
Ops.push_back(Op);
}
// BUILD_VECTOR requires all inputs to be of the same type, find the
// maximum type and extend them all.
EVT SVT = VT.getScalarType();