diff options
Diffstat (limited to 'llvm/lib/Target/X86/X86ISelLowering.cpp')
| -rw-r--r-- | llvm/lib/Target/X86/X86ISelLowering.cpp | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index cf8304e565a..56f62dce002 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -19868,7 +19868,10 @@ static SDValue getGatherNode(unsigned Opc, SDValue Op, SelectionDAG &DAG, SDVTList VTs = DAG.getVTList(Op.getValueType(), MaskVT, MVT::Other); SDValue Disp = DAG.getTargetConstant(0, dl, MVT::i32); SDValue Segment = DAG.getRegister(0, MVT::i32); - if (Src.isUndef()) + // If source is undef or we know it won't be used, use a zero vector + // to break register dependency. + // TODO: use undef instead and let ExeDepsFix deal with it? + if (Src.isUndef() || ISD::isBuildVectorAllOnes(VMask.getNode())) Src = getZeroVector(Op.getSimpleValueType(), Subtarget, DAG, dl); SDValue Ops[] = {Src, VMask, Base, Scale, Index, Disp, Segment, Chain}; SDNode *Res = DAG.getMachineNode(Opc, dl, VTs, Ops); |
