diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp | 9 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/div.ll | 10 |
2 files changed, 12 insertions, 7 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp index d5a36e025f6..19766d502c4 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -1692,9 +1692,12 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) { Builder.CreateNot(Y, Y->getName() + ".not")); // 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()) { - auto *BO = BinaryOperator::CreateSDiv(X, ConstantExpr::getNeg(C)); + // TODO: This could be extended to match arbitrary vector constants. + const APInt *DivC; + if (match(Op0, m_Zero()) && match(Op1, m_SDiv(m_Value(X), m_APInt(DivC))) && + !DivC->isMinSignedValue() && *DivC != 1) { + Constant *NegDivC = ConstantInt::get(I.getType(), -(*DivC)); + Instruction *BO = BinaryOperator::CreateSDiv(X, NegDivC); BO->setIsExact(cast<BinaryOperator>(Op1)->isExact()); return BO; } diff --git a/llvm/test/Transforms/InstCombine/div.ll b/llvm/test/Transforms/InstCombine/div.ll index 00d4bd7ce28..215d16c1213 100644 --- a/llvm/test/Transforms/InstCombine/div.ll +++ b/llvm/test/Transforms/InstCombine/div.ll @@ -772,7 +772,8 @@ define i32 @test_exact_nsw_exact(i32 %x) { define <2 x i64> @test_exact_vec(<2 x i64> %x) { ; CHECK-LABEL: @test_exact_vec( -; CHECK-NEXT: [[NEG:%.*]] = sdiv exact <2 x i64> [[X:%.*]], <i64 -3, i64 -4> +; CHECK-NEXT: [[DIV:%.*]] = sdiv exact <2 x i64> [[X:%.*]], <i64 3, i64 4> +; CHECK-NEXT: [[NEG:%.*]] = sub nsw <2 x i64> zeroinitializer, [[DIV]] ; CHECK-NEXT: ret <2 x i64> [[NEG]] ; %div = sdiv exact <2 x i64> %x, <i64 3, i64 4> @@ -832,7 +833,8 @@ define <2 x i8> @negate_sdiv_vec_splat_signed_min(<2 x i8> %x) { define <2 x i8> @negate_sdiv_vec_one_element(<2 x i8> %x) { ; CHECK-LABEL: @negate_sdiv_vec_one_element( -; CHECK-NEXT: [[NEG:%.*]] = sdiv <2 x i8> [[X:%.*]], <i8 1, i8 -1> +; CHECK-NEXT: [[DIV:%.*]] = sdiv <2 x i8> [[X:%.*]], <i8 -1, i8 1> +; CHECK-NEXT: [[NEG:%.*]] = sub <2 x i8> zeroinitializer, [[DIV]] ; CHECK-NEXT: ret <2 x i8> [[NEG]] ; %div = sdiv <2 x i8> %x, <i8 -1, i8 1> @@ -840,7 +842,7 @@ define <2 x i8> @negate_sdiv_vec_one_element(<2 x i8> %x) { ret <2 x i8> %neg } -; Division by -1 may be UB and can't negate signed-min. +; Can't negate signed-min constant for any element of a vector. define <2 x i8> @negate_sdiv_vec_signed_min_elt(<2 x i8> %x) { ; CHECK-LABEL: @negate_sdiv_vec_signed_min_elt( @@ -853,7 +855,7 @@ define <2 x i8> @negate_sdiv_vec_signed_min_elt(<2 x i8> %x) { ret <2 x i8> %neg } -; Can't negate signed-min constant for any element of a vector. +; Division by -1 may be UB and can't negate signed-min. define <2 x i8> @negate_sdiv_vec_signed_min_and_one_elt(<2 x i8> %x) { ; CHECK-LABEL: @negate_sdiv_vec_signed_min_and_one_elt( |
