diff options
Diffstat (limited to 'llvm/lib/Target/RISCV/RISCVISelLowering.cpp')
| -rw-r--r-- | llvm/lib/Target/RISCV/RISCVISelLowering.cpp | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp index 4cb3188..ff63b22 100644 --- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp +++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp @@ -6918,7 +6918,10 @@ void RISCVTargetLowering::ReplaceNodeResults(SDNode *N, SDValue Overflow; if (IsAdd && isOneConstant(RHS)) { // Special case uaddo X, 1 overflowed if the addition result is 0. - // FIXME: We can do this for any constant RHS by using (X + C) < C. + // The general case (X + C) < C is not necessarily beneficial. Although we + // reduce the live range of X, we may introduce the materialization of + // constant C, especially when the setcc result is used by branch. We have + // no compare with constant and branch instructions. Overflow = DAG.getSetCC(DL, N->getValueType(1), Res, DAG.getConstant(0, DL, MVT::i64), ISD::SETEQ); } else { |