diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineAddSub.cpp | 5 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/sub-xor.ll | 10 |
2 files changed, 15 insertions, 0 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp index 1aa51d06cb..166f8dfdb4 100644 --- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -974,6 +974,11 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { return BinaryOperator::CreateSub(ConstantExpr::getAdd(XorRHS, CI), XorLHS); } + // (X + signbit) + C could have gotten canonicalized to (X ^ signbit) + C, + // transform them into (X + (signbit ^ C)) + if (XorRHS->getValue().isSignBit()) + return BinaryOperator::CreateAdd(XorLHS, + ConstantExpr::getXor(XorRHS, CI)); } } diff --git a/test/Transforms/InstCombine/sub-xor.ll b/test/Transforms/InstCombine/sub-xor.ll index 279e4aca9d..1d14852bc8 100644 --- a/test/Transforms/InstCombine/sub-xor.ll +++ b/test/Transforms/InstCombine/sub-xor.ll @@ -35,3 +35,13 @@ define i32 @test3(i32 %x) nounwind { ; CHECK-NEXT: sub i32 73, %and ; CHECK-NEXT: ret } + +define i32 @test4(i32 %x) nounwind { + %sub = xor i32 %x, 2147483648 + %add = add i32 %sub, 42 + ret i32 %add + +; CHECK: @test4 +; CHECK-NEXT: add i32 %x, -2147483606 +; CHECK-NEXT: ret +} |