diff options
Diffstat (limited to 'llvm/lib/Target/X86/X86ISelLowering.cpp')
| -rw-r--r-- | llvm/lib/Target/X86/X86ISelLowering.cpp | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index 88a3b27aa98..ea4fe8c6712 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -35402,6 +35402,18 @@ static SDValue combineBitcast(SDNode *N, SelectionDAG &DAG, } } + // Look for (i8 (bitcast (v8i1 (extract_subvector (v16i1 X), 0)))) and + // replace with (i8 (trunc (i16 (bitcast (v16i1 X))))). This can occur + // due to insert_subvector legalization on KNL. By promoting the copy to i16 + // we can help with known bits propagation from the vXi1 domain to the + // scalar domain. + if (VT == MVT::i8 && SrcVT == MVT::v8i1 && Subtarget.hasAVX512() && + !Subtarget.hasDQI() && N0.getOpcode() == ISD::EXTRACT_SUBVECTOR && + N0.getOperand(0).getValueType() == MVT::v16i1 && + isNullConstant(N0.getOperand(1))) + return DAG.getNode(ISD::TRUNCATE, SDLoc(N), VT, + DAG.getBitcast(MVT::i16, N0.getOperand(0))); + // Since MMX types are special and don't usually play with other vector types, // it's better to handle them early to be sure we emit efficient code by // avoiding store-load conversions. |
