diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp | 13 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/cast.ll | 12 |
2 files changed, 22 insertions, 3 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp index cd391d0385e..0695ec17e36 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp @@ -83,11 +83,18 @@ bool InstCombiner::SimplifyDemandedInstructionBits(Instruction &Inst) { bool InstCombiner::SimplifyDemandedBits(Use &U, APInt DemandedMask, APInt &KnownZero, APInt &KnownOne, unsigned Depth) { - Value *NewVal = - SimplifyDemandedUseBits(U.get(), DemandedMask, KnownZero, KnownOne, Depth, - dyn_cast<Instruction>(U.getUser())); + auto *UserI = dyn_cast<Instruction>(U.getUser()); + Value *NewVal = SimplifyDemandedUseBits(U.get(), DemandedMask, KnownZero, + KnownOne, Depth, UserI); if (!NewVal) return false; U = NewVal; + + // Shrinking a constant might cause a nsw/nuw violation to occur in + // instructions which are themselves demanded. + if (auto *UserOBO = dyn_cast<OverflowingBinaryOperator>(UserI)) { + cast<BinaryOperator>(UserOBO)->setHasNoSignedWrap(false); + cast<BinaryOperator>(UserOBO)->setHasNoUnsignedWrap(false); + } return true; } diff --git a/llvm/test/Transforms/InstCombine/cast.ll b/llvm/test/Transforms/InstCombine/cast.ll index d4356d9364b..7bf4a6047f2 100644 --- a/llvm/test/Transforms/InstCombine/cast.ll +++ b/llvm/test/Transforms/InstCombine/cast.ll @@ -1113,3 +1113,15 @@ define float @sitofp_zext(i16 %a) { %sitofp = sitofp i32 %zext to float ret float %sitofp } + +define i1 @PR23309(i32 %A, i32 %B) { +; CHECK-LABEL: @PR23309( +; CHECK-NEXT: %[[sub:.*]] = sub i32 %A, %B +; CHECK-NEXT: %[[and:.*]] = and i32 %[[sub]], 1 +; CHECK-NEXT: %[[cmp:.*]] = icmp ne i32 %[[and]], 0 +; CHECK-NEXT: ret i1 %[[cmp]] + %add = add i32 %A, -4 + %sub = sub nsw i32 %add, %B + %trunc = trunc i32 %sub to i1 + ret i1 %trunc +} |
