Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp =================================================================== --- llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -1693,8 +1693,11 @@ // 0 - (X sdiv C) -> (X sdiv -C) provided the negation doesn't overflow. if (match(Op1, m_SDiv(m_Value(X), m_Constant(C))) && match(Op0, m_Zero()) && - C->isNotMinSignedValue() && !C->isOneValue()) - return BinaryOperator::CreateSDiv(X, ConstantExpr::getNeg(C)); + C->isNotMinSignedValue() && !C->isOneValue()) { + auto *BO = BinaryOperator::CreateSDiv(X, ConstantExpr::getNeg(C)); + BO->setIsExact(cast(Op1)->isExact()); + return BO; + } // 0 - (X << Y) -> (-X << Y) when X is freely negatable. if (match(Op1, m_Shl(m_Value(X), m_Value(Y))) && match(Op0, m_Zero())) Index: llvm/trunk/test/Transforms/InstCombine/div.ll =================================================================== --- llvm/trunk/test/Transforms/InstCombine/div.ll +++ llvm/trunk/test/Transforms/InstCombine/div.ll @@ -762,7 +762,7 @@ define i32 @test_exact_nsw_exact(i32 %x) { ; CHECK-LABEL: @test_exact_nsw_exact( -; CHECK-NEXT: [[NEG:%.*]] = sdiv i32 [[X:%.*]], -3 +; CHECK-NEXT: [[NEG:%.*]] = sdiv exact i32 [[X:%.*]], -3 ; CHECK-NEXT: ret i32 [[NEG]] ; %div = sdiv exact i32 %x, 3 @@ -772,7 +772,7 @@ define <2 x i64> @test_exact_vec(<2 x i64> %x) { ; CHECK-LABEL: @test_exact_vec( -; CHECK-NEXT: [[NEG:%.*]] = sdiv <2 x i64> [[X:%.*]], +; CHECK-NEXT: [[NEG:%.*]] = sdiv exact <2 x i64> [[X:%.*]], ; CHECK-NEXT: ret <2 x i64> [[NEG]] ; %div = sdiv exact <2 x i64> %x, @@ -782,7 +782,7 @@ define i32 @test_exact_nonsw_exact(i32 %x) { ; CHECK-LABEL: @test_exact_nonsw_exact( -; CHECK-NEXT: [[NEG:%.*]] = sdiv i32 [[X:%.*]], -3 +; CHECK-NEXT: [[NEG:%.*]] = sdiv exact i32 [[X:%.*]], -3 ; CHECK-NEXT: ret i32 [[NEG]] ; %div = sdiv exact i32 %x, 3 @@ -806,7 +806,7 @@ ; CHECK-NEXT: ret i32 [[NEG]] ; %div = sdiv i32 %x, 3 - %neg = sub nsw i32 0, %div + %neg = sub i32 0, %div ret i32 %neg }