diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp --- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -1924,6 +1924,23 @@ A->getType()->isIntOrIntVectorTy(1)) return SelectInst::Create(A, Op0, Constant::getNullValue(I.getType())); + // and(ashr(sub(0, V), ScalarSizeInBits -1), V) --> V s< 0 ? 0 : V, where sub + // hasNoSignedWrap. + { + Value *Shift, *V; + const APInt *ShAmt; + Type *Ty = I.getType(); + if (match(&I, m_c_And(m_Value(Shift), m_Value(V))) && + match(Shift, + m_OneUse(m_AShr(m_OneUse(m_NSWSub(m_Zero(), m_Specific(V))), + m_APInt(ShAmt)))) && + *ShAmt == Ty->getScalarSizeInBits() - 1) { + Value *NewICmpInst = + Builder.CreateICmpSLT(V, ConstantInt::getNullValue(Ty)); + return SelectInst::Create(NewICmpInst, ConstantInt::getNullValue(Ty), V); + } + } + return nullptr; } diff --git a/llvm/test/Transforms/InstCombine/sub-ashr-and-to-icmp-select.ll b/llvm/test/Transforms/InstCombine/sub-ashr-and-to-icmp-select.ll --- a/llvm/test/Transforms/InstCombine/sub-ashr-and-to-icmp-select.ll +++ b/llvm/test/Transforms/InstCombine/sub-ashr-and-to-icmp-select.ll @@ -11,9 +11,8 @@ define i8 @sub_ashr_and_i8(i8 %v) { ; CHECK-LABEL: @sub_ashr_and_i8( -; CHECK-NEXT: [[SUB:%.*]] = sub nsw i8 0, [[V:%.*]] -; CHECK-NEXT: [[SHR:%.*]] = ashr i8 [[SUB]], 7 -; CHECK-NEXT: [[AND:%.*]] = and i8 [[SHR]], [[V]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i8 [[V:%.*]], 0 +; CHECK-NEXT: [[AND:%.*]] = select i1 [[TMP1]], i8 [[V]], i8 0 ; CHECK-NEXT: ret i8 [[AND]] ; %sub = sub nsw i8 0, %v @@ -24,9 +23,8 @@ define i16 @sub_ashr_and_i16(i16 %v) { ; CHECK-LABEL: @sub_ashr_and_i16( -; CHECK-NEXT: [[SUB:%.*]] = sub nsw i16 0, [[V:%.*]] -; CHECK-NEXT: [[SHR:%.*]] = ashr i16 [[SUB]], 15 -; CHECK-NEXT: [[AND:%.*]] = and i16 [[SHR]], [[V]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i16 [[V:%.*]], 0 +; CHECK-NEXT: [[AND:%.*]] = select i1 [[TMP1]], i16 [[V]], i16 0 ; CHECK-NEXT: ret i16 [[AND]] ; @@ -38,9 +36,8 @@ define i32 @sub_ashr_and_i32(i32 %v) { ; CHECK-LABEL: @sub_ashr_and_i32( -; CHECK-NEXT: [[SUB:%.*]] = sub nsw i32 0, [[V:%.*]] -; CHECK-NEXT: [[SHR:%.*]] = ashr i32 [[SUB]], 31 -; CHECK-NEXT: [[AND:%.*]] = and i32 [[SHR]], [[V]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i32 [[V:%.*]], 0 +; CHECK-NEXT: [[AND:%.*]] = select i1 [[TMP1]], i32 [[V]], i32 0 ; CHECK-NEXT: ret i32 [[AND]] ; %sub = sub nsw i32 0, %v @@ -51,9 +48,8 @@ define i64 @sub_ashr_and_i64(i64 %v) { ; CHECK-LABEL: @sub_ashr_and_i64( -; CHECK-NEXT: [[SUB:%.*]] = sub nsw i64 0, [[V:%.*]] -; CHECK-NEXT: [[SHR:%.*]] = ashr i64 [[SUB]], 63 -; CHECK-NEXT: [[AND:%.*]] = and i64 [[SHR]], [[V]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i64 [[V:%.*]], 0 +; CHECK-NEXT: [[AND:%.*]] = select i1 [[TMP1]], i64 [[V]], i64 0 ; CHECK-NEXT: ret i64 [[AND]] ; %sub = sub nsw i64 0, %v @@ -78,9 +74,8 @@ define i32 @sub_ashr_and_i32_commute(i32 %v) { ; CHECK-LABEL: @sub_ashr_and_i32_commute( -; CHECK-NEXT: [[SUB:%.*]] = sub nsw i32 0, [[V:%.*]] -; CHECK-NEXT: [[SHR:%.*]] = ashr i32 [[SUB]], 31 -; CHECK-NEXT: [[AND:%.*]] = and i32 [[SHR]], [[V]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i32 [[V:%.*]], 0 +; CHECK-NEXT: [[AND:%.*]] = select i1 [[TMP1]], i32 [[V]], i32 0 ; CHECK-NEXT: ret i32 [[AND]] ; %sub = sub nsw i32 0, %v @@ -93,9 +88,8 @@ define <4 x i32> @sub_ashr_and_i32_vec(<4 x i32> %v) { ; CHECK-LABEL: @sub_ashr_and_i32_vec( -; CHECK-NEXT: [[SUB:%.*]] = sub nsw <4 x i32> zeroinitializer, [[V:%.*]] -; CHECK-NEXT: [[SHR:%.*]] = ashr <4 x i32> [[SUB]], -; CHECK-NEXT: [[AND:%.*]] = and <4 x i32> [[SHR]], [[V]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt <4 x i32> [[V:%.*]], zeroinitializer +; CHECK-NEXT: [[AND:%.*]] = select <4 x i1> [[TMP1]], <4 x i32> [[V]], <4 x i32> zeroinitializer ; CHECK-NEXT: ret <4 x i32> [[AND]] ; %sub = sub nsw <4 x i32> zeroinitializer, %v @@ -116,9 +110,8 @@ define <4 x i32> @sub_ashr_and_i32_vec_commute(<4 x i32> %v) { ; CHECK-LABEL: @sub_ashr_and_i32_vec_commute( -; CHECK-NEXT: [[SUB:%.*]] = sub nsw <4 x i32> zeroinitializer, [[V:%.*]] -; CHECK-NEXT: [[SHR:%.*]] = ashr <4 x i32> [[SUB]], -; CHECK-NEXT: [[AND:%.*]] = and <4 x i32> [[SHR]], [[V]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt <4 x i32> [[V:%.*]], zeroinitializer +; CHECK-NEXT: [[AND:%.*]] = select <4 x i1> [[TMP1]], <4 x i32> [[V]], <4 x i32> zeroinitializer ; CHECK-NEXT: ret <4 x i32> [[AND]] ; %sub = sub nsw <4 x i32> zeroinitializer, %v @@ -131,9 +124,8 @@ define i32 @sub_ashr_and_i32_extra_use_and(i32 %v, i32* %p) { ; CHECK-LABEL: @sub_ashr_and_i32_extra_use_and( -; CHECK-NEXT: [[SUB:%.*]] = sub nsw i32 0, [[V:%.*]] -; CHECK-NEXT: [[SHR:%.*]] = ashr i32 [[SUB]], 31 -; CHECK-NEXT: [[AND:%.*]] = and i32 [[SHR]], [[V]] +; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i32 [[V:%.*]], 0 +; CHECK-NEXT: [[AND:%.*]] = select i1 [[TMP1]], i32 [[V]], i32 0 ; CHECK-NEXT: store i32 [[AND]], i32* [[P:%.*]], align 4 ; CHECK-NEXT: ret i32 [[AND]] ;