diff options
Diffstat (limited to 'llvm/lib/Analysis/ConstantFolding.cpp')
| -rw-r--r-- | llvm/lib/Analysis/ConstantFolding.cpp | 29 |
1 files changed, 18 insertions, 11 deletions
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp index f7cc53b345f..cedd788d226 100644 --- a/llvm/lib/Analysis/ConstantFolding.cpp +++ b/llvm/lib/Analysis/ConstantFolding.cpp @@ -2041,20 +2041,27 @@ static Constant *ConstantFoldScalarCall2(StringRef Name, switch (IntrinsicID) { default: break; + case Intrinsic::usub_with_overflow: + case Intrinsic::ssub_with_overflow: + case Intrinsic::uadd_with_overflow: + case Intrinsic::sadd_with_overflow: + // X - undef -> { undef, false } + // undef - X -> { undef, false } + // X + undef -> { undef, false } + // undef + x -> { undef, false } + if (!C0 || !C1) { + return ConstantStruct::get( + cast<StructType>(Ty), + {UndefValue::get(Ty->getStructElementType(0)), + Constant::getNullValue(Ty->getStructElementType(1))}); + } + LLVM_FALLTHROUGH; case Intrinsic::smul_with_overflow: - case Intrinsic::umul_with_overflow: - // Even if both operands are undef, we cannot fold muls to undef - // in the general case. For example, on i2 there are no inputs - // that would produce { i2 -1, i1 true } as the result. + case Intrinsic::umul_with_overflow: { + // undef * X -> { 0, false } + // X * undef -> { 0, false } if (!C0 || !C1) return Constant::getNullValue(Ty); - LLVM_FALLTHROUGH; - case Intrinsic::sadd_with_overflow: - case Intrinsic::uadd_with_overflow: - case Intrinsic::ssub_with_overflow: - case Intrinsic::usub_with_overflow: { - if (!C0 || !C1) - return UndefValue::get(Ty); APInt Res; bool Overflow; |
