diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp --- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -2098,6 +2098,12 @@ canonicalizeCondSignextOfHighBitExtractToSignextHighBitExtract(I)) return V; + // X - usub.sat(X, Y) => umin(X, Y) + if (match(Op1, m_OneUse(m_Intrinsic(m_Specific(Op0), + m_Value(Y))))) + return replaceInstUsesWith( + I, Builder.CreateIntrinsic(Intrinsic::umin, {I.getType()}, {Op0, Y})); + return TryToNarrowDeduceFlags(); } diff --git a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll --- a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll +++ b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll @@ -1098,9 +1098,8 @@ define i8 @test_scalar_usub_sub(i8 %a, i8 %b) { ; CHECK-LABEL: @test_scalar_usub_sub( -; CHECK-NEXT: [[SAT:%.*]] = call i8 @llvm.usub.sat.i8(i8 [[A:%.*]], i8 [[B:%.*]]) -; CHECK-NEXT: [[RES:%.*]] = sub i8 [[A]], [[SAT]] -; CHECK-NEXT: ret i8 [[RES]] +; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.umin.i8(i8 [[A:%.*]], i8 [[B:%.*]]) +; CHECK-NEXT: ret i8 [[TMP1]] ; %sat = call i8 @llvm.usub.sat.i8(i8 %a, i8 %b) %res = sub i8 %a, %sat @@ -1122,9 +1121,8 @@ define <2 x i8> @test_vector_usub_sub(<2 x i8> %a, <2 x i8> %b) { ; CHECK-LABEL: @test_vector_usub_sub( -; CHECK-NEXT: [[SAT:%.*]] = call <2 x i8> @llvm.usub.sat.v2i8(<2 x i8> [[A:%.*]], <2 x i8> [[B:%.*]]) -; CHECK-NEXT: [[RES:%.*]] = sub <2 x i8> [[A]], [[SAT]] -; CHECK-NEXT: ret <2 x i8> [[RES]] +; CHECK-NEXT: [[TMP1:%.*]] = call <2 x i8> @llvm.umin.v2i8(<2 x i8> [[A:%.*]], <2 x i8> [[B:%.*]]) +; CHECK-NEXT: ret <2 x i8> [[TMP1]] ; %sat = call <2 x i8> @llvm.usub.sat.v2i8(<2 x i8> %a, <2 x i8> %b) %res = sub <2 x i8> %a, %sat