diff options
Diffstat (limited to 'lib/Analysis/ValueTracking.cpp')
| -rw-r--r-- | lib/Analysis/ValueTracking.cpp | 26 |
1 files changed, 18 insertions, 8 deletions
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp index 2730daefa625..cd4cee631568 100644 --- a/lib/Analysis/ValueTracking.cpp +++ b/lib/Analysis/ValueTracking.cpp @@ -4238,14 +4238,14 @@ static SelectPatternResult matchSelectPattern(CmpInst::Predicate Pred, LHS = CmpLHS; RHS = CmpRHS; - // If the predicate is an "or-equal" (FP) predicate, then signed zeroes may - // return inconsistent results between implementations. - // (0.0 <= -0.0) ? 0.0 : -0.0 // Returns 0.0 - // minNum(0.0, -0.0) // May return -0.0 or 0.0 (IEEE 754-2008 5.3.1) - // Therefore we behave conservatively and only proceed if at least one of the - // operands is known to not be zero, or if we don't care about signed zeroes. + // Signed zero may return inconsistent results between implementations. + // (0.0 <= -0.0) ? 0.0 : -0.0 // Returns 0.0 + // minNum(0.0, -0.0) // May return -0.0 or 0.0 (IEEE 754-2008 5.3.1) + // Therefore, we behave conservatively and only proceed if at least one of the + // operands is known to not be zero or if we don't care about signed zero. switch (Pred) { default: break; + // FIXME: Include OGT/OLT/UGT/ULT. case CmpInst::FCMP_OGE: case CmpInst::FCMP_OLE: case CmpInst::FCMP_UGE: case CmpInst::FCMP_ULE: if (!FMF.noSignedZeros() && !isKnownNonZero(CmpLHS) && @@ -4493,14 +4493,24 @@ SelectPatternResult llvm::matchSelectPattern(Value *V, Value *&LHS, Value *&RHS, // Deal with type mismatches. if (CastOp && CmpLHS->getType() != TrueVal->getType()) { - if (Value *C = lookThroughCast(CmpI, TrueVal, FalseVal, CastOp)) + if (Value *C = lookThroughCast(CmpI, TrueVal, FalseVal, CastOp)) { + // If this is a potential fmin/fmax with a cast to integer, then ignore + // -0.0 because there is no corresponding integer value. + if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI) + FMF.setNoSignedZeros(); return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, cast<CastInst>(TrueVal)->getOperand(0), C, LHS, RHS); - if (Value *C = lookThroughCast(CmpI, FalseVal, TrueVal, CastOp)) + } + if (Value *C = lookThroughCast(CmpI, FalseVal, TrueVal, CastOp)) { + // If this is a potential fmin/fmax with a cast to integer, then ignore + // -0.0 because there is no corresponding integer value. + if (*CastOp == Instruction::FPToSI || *CastOp == Instruction::FPToUI) + FMF.setNoSignedZeros(); return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, C, cast<CastInst>(FalseVal)->getOperand(0), LHS, RHS); + } } return ::matchSelectPattern(Pred, FMF, CmpLHS, CmpRHS, TrueVal, FalseVal, LHS, RHS); |