diff options
Diffstat (limited to 'lib')
-rw-r--r-- | lib/Target/X86/X86ISelLowering.cpp | 45 |
1 files changed, 39 insertions, 6 deletions
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp index 815d27ff5e..306fb7e199 100644 --- a/lib/Target/X86/X86ISelLowering.cpp +++ b/lib/Target/X86/X86ISelLowering.cpp @@ -5703,6 +5703,41 @@ static SDValue LowerVectorBroadcast(SDValue Op, const X86Subtarget* Subtarget, return SDValue(); } +/// \brief For an EXTRACT_VECTOR_ELT with a constant index return the real +/// underlying vector and index. +/// +/// Modifies \p ExtractedFromVec to the real vector and returns the real +/// index. +static int getUnderlyingExtractedFromVec(SDValue &ExtractedFromVec, + SDValue ExtIdx) { + int Idx = cast<ConstantSDNode>(ExtIdx)->getZExtValue(); + if (!isa<ShuffleVectorSDNode>(ExtractedFromVec)) + return Idx; + + // For 256-bit vectors, LowerEXTRACT_VECTOR_ELT_SSE4 may have already + // lowered this: + // (extract_vector_elt (v8f32 %vreg1), Constant<6>) + // to: + // (extract_vector_elt (vector_shuffle<2,u,u,u> + // (extract_subvector (v8f32 %vreg0), Constant<4>), + // undef) + // Constant<0>) + // In this case the vector is the extract_subvector expression and the index + // is 2, as specified by the shuffle. + ShuffleVectorSDNode *SVOp = cast<ShuffleVectorSDNode>(ExtractedFromVec); + SDValue ShuffleVec = SVOp->getOperand(0); + MVT ShuffleVecVT = ShuffleVec.getSimpleValueType(); + assert(ShuffleVecVT.getVectorElementType() == + ExtractedFromVec.getSimpleValueType().getVectorElementType()); + + int ShuffleIdx = SVOp->getMaskElt(Idx); + if (isUndefOrInRange(ShuffleIdx, 0, ShuffleVecVT.getVectorNumElements())) { + ExtractedFromVec = ShuffleVec; + return ShuffleIdx; + } + return Idx; +} + static SDValue buildFromShuffleMostly(SDValue Op, SelectionDAG &DAG) { MVT VT = Op.getSimpleValueType(); @@ -5736,15 +5771,15 @@ static SDValue buildFromShuffleMostly(SDValue Op, SelectionDAG &DAG) { SDValue ExtractedFromVec = Op.getOperand(i).getOperand(0); SDValue ExtIdx = Op.getOperand(i).getOperand(1); + // Quit if non-constant index. + if (!isa<ConstantSDNode>(ExtIdx)) + return SDValue(); + int Idx = getUnderlyingExtractedFromVec(ExtractedFromVec, ExtIdx); // Quit if extracted from vector of different type. if (ExtractedFromVec.getValueType() != VT) return SDValue(); - // Quit if non-constant index. - if (!isa<ConstantSDNode>(ExtIdx)) - return SDValue(); - if (VecIn1.getNode() == 0) VecIn1 = ExtractedFromVec; else if (VecIn1 != ExtractedFromVec) { @@ -5755,8 +5790,6 @@ static SDValue buildFromShuffleMostly(SDValue Op, SelectionDAG &DAG) { return SDValue(); } - unsigned Idx = cast<ConstantSDNode>(ExtIdx)->getZExtValue(); - if (ExtractedFromVec == VecIn1) Mask[i] = Idx; else if (ExtractedFromVec == VecIn2) |