diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp | 3 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/div.ll | 17 |
2 files changed, 19 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index 8d004f2a0a2..b09198afff2 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -762,7 +762,8 @@ Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) { } } - if ((IsSigned && match(LHS, m_NSWShl(m_Value(X), m_APInt(C1)))) || + if ((IsSigned && match(LHS, m_NSWShl(m_Value(X), m_APInt(C1))) && + *C1 != C1->getBitWidth() - 1) || (!IsSigned && match(LHS, m_NUWShl(m_Value(X), m_APInt(C1))))) { APInt Quotient(C1->getBitWidth(), /*Val=*/0ULL, IsSigned); APInt C1Shifted = APInt::getOneBitSet( diff --git a/llvm/test/Transforms/InstCombine/div.ll b/llvm/test/Transforms/InstCombine/div.ll index 26e9e336823..5a884ac671d 100644 --- a/llvm/test/Transforms/InstCombine/div.ll +++ b/llvm/test/Transforms/InstCombine/div.ll @@ -247,3 +247,20 @@ define i32 @test28(i32 %a) { ; CHECK-NEXT: %div = mul nuw i32 %a, 12 ; CHECK-NEXT: ret i32 %div } + +define i32 @test29(i32 %a) { + %mul = shl nsw i32 %a, 31 + %div = sdiv i32 %mul, -2147483648 + ret i32 %div +; CHECK-LABEL: @test29( +; CHECK-NEXT: %[[and:.*]] = and i32 %a, 1 +; CHECK-NEXT: ret i32 %[[and]] +} + +define i32 @test30(i32 %a) { + %mul = shl nuw i32 %a, 31 + %div = udiv i32 %mul, -2147483648 + ret i32 %div +; CHECK-LABEL: @test30( +; CHECK-NEXT: ret i32 %a +} |
