diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Target/X86/X86ISelLowering.cpp | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index ed6700f4279..704b62d0ca9 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -19383,13 +19383,26 @@ static SDValue LowerVSETCC(SDValue Op, const X86Subtarget &Subtarget, bool FlipSigns = ISD::isUnsignedIntSetCC(Cond) && !(DAG.SignBitIsZero(Op0) && DAG.SignBitIsZero(Op1)); - // Special case: Use min/max operations for unsigned compares. We only want - // to do this for unsigned compares if we need to flip signs or if it allows - // use to avoid an invert. + // Special case: Use min/max operations for unsigned compares. const TargetLowering &TLI = DAG.getTargetLoweringInfo(); if (ISD::isUnsignedIntSetCC(Cond) && (FlipSigns || ISD::isTrueWhenEqual(Cond)) && TLI.isOperationLegal(ISD::UMIN, VT)) { + // If we have a constant operand, increment/decrement it and change the + // condition to avoid an invert. + // TODO: This could be extended to handle a non-splat constant by checking + // that each element of the constant is not the max/null value. + APInt C; + if (Cond == ISD::SETUGT && isConstantSplat(Op1, C) && !C.isMaxValue()) { + // X > C --> X >= (C+1) --> X == umax(X, C+1) + Op1 = DAG.getConstant(C + 1, dl, VT); + Cond = ISD::SETUGE; + } + if (Cond == ISD::SETULT && isConstantSplat(Op1, C) && !C.isNullValue()) { + // X < C --> X <= (C-1) --> X == umin(X, C-1) + Op1 = DAG.getConstant(C - 1, dl, VT); + Cond = ISD::SETULE; + } bool Invert = false; unsigned Opc; switch (Cond) { |
