diff options
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/lib/Target/X86/X86ISelLowering.cpp | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index 4e4b2b1a6d3..0d65c277725 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -32350,9 +32350,14 @@ static SDValue combineTruncatedArithmetic(SDNode *N, SelectionDAG &DAG, auto IsRepeatedOpOrFreeTruncation = [VT](SDValue Op0, SDValue Op1) { unsigned TruncSizeInBits = VT.getScalarSizeInBits(); + + // Repeated operand, so we are only trading one output truncation for + // one input truncation. if (Op0 == Op1) return true; + // See if either operand has been extended from a smaller/equal size to + // the truncation size, allowing a truncation to combine with the extend. unsigned Opcode0 = Op0.getOpcode(); if ((Opcode0 == ISD::ANY_EXTEND || Opcode0 == ISD::SIGN_EXTEND || Opcode0 == ISD::ZERO_EXTEND) && @@ -32365,6 +32370,8 @@ static SDValue combineTruncatedArithmetic(SDNode *N, SelectionDAG &DAG, Op1.getOperand(0).getScalarValueSizeInBits() <= TruncSizeInBits) return true; + // See if either operand is a single use constant which can be constant + // folded. SDValue BC0 = peekThroughOneUseBitcasts(Op0); SDValue BC1 = peekThroughOneUseBitcasts(Op1); return ISD::isBuildVectorOfConstantSDNodes(BC0.getNode()) || |
