diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp | 6 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/unsigned_saturated_sub.ll | 19 |
2 files changed, 12 insertions, 13 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp index bdfbd75d31a..0b6b7c3c66d 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -711,9 +711,9 @@ static Value *canonicalizeSaturatedSubtract(const ICmpInst *ICI, else if (!match(TrueVal, m_Sub(m_Specific(A), m_Specific(B)))) return nullptr; - // If sub is used anywhere else, we wouldn't be able to eliminate it - // afterwards. - if (!TrueVal->hasOneUse()) + // If we are adding a negate and the sub and icmp are used anywhere else, we + // would end up with more instructions. + if (IsNegative && !TrueVal->hasOneUse() && !ICI->hasOneUse()) return nullptr; // (a > b) ? a - b : 0 -> usub.sat(a, b) diff --git a/llvm/test/Transforms/InstCombine/unsigned_saturated_sub.ll b/llvm/test/Transforms/InstCombine/unsigned_saturated_sub.ll index a5b15040ac7..4fa1b182d67 100644 --- a/llvm/test/Transforms/InstCombine/unsigned_saturated_sub.ll +++ b/llvm/test/Transforms/InstCombine/unsigned_saturated_sub.ll @@ -36,11 +36,10 @@ define i64 @max_sub_uge(i64 %a, i64 %b) { define i64 @max_sub_uge_extrause1(i64 %a, i64 %b) { ; CHECK-LABEL: @max_sub_uge_extrause1( -; CHECK-NEXT: [[CMP:%.*]] = icmp ult i64 [[A:%.*]], [[B:%.*]] -; CHECK-NEXT: [[SUB:%.*]] = sub i64 [[A]], [[B]] -; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i64 0, i64 [[SUB]] +; CHECK-NEXT: [[SUB:%.*]] = sub i64 [[A:%.*]], [[B:%.*]] +; CHECK-NEXT: [[TMP1:%.*]] = call i64 @llvm.usub.sat.i64(i64 [[A]], i64 [[B]]) ; CHECK-NEXT: call void @use(i64 [[SUB]]) -; CHECK-NEXT: ret i64 [[SEL]] +; CHECK-NEXT: ret i64 [[TMP1]] ; %cmp = icmp uge i64 %a, %b %sub = sub i64 %a, %b @@ -67,10 +66,10 @@ define i64 @max_sub_uge_extrause3(i64 %a, i64 %b) { ; CHECK-LABEL: @max_sub_uge_extrause3( ; CHECK-NEXT: [[CMP:%.*]] = icmp uge i64 [[A:%.*]], [[B:%.*]] ; CHECK-NEXT: [[SUB:%.*]] = sub i64 [[A]], [[B]] -; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i64 [[SUB]], i64 0 +; CHECK-NEXT: [[TMP1:%.*]] = call i64 @llvm.usub.sat.i64(i64 [[A]], i64 [[B]]) ; CHECK-NEXT: call void @use(i64 [[SUB]]) ; CHECK-NEXT: call void @usei1(i1 [[CMP]]) -; CHECK-NEXT: ret i64 [[SEL]] +; CHECK-NEXT: ret i64 [[TMP1]] ; %cmp = icmp uge i64 %a, %b %sub = sub i64 %a, %b @@ -205,11 +204,11 @@ define i64 @neg_max_sub_ugt_sel_swapped_extrause1(i64 %a, i64 %b) { define i64 @neg_max_sub_ugt_sel_swapped_extrause2(i64 %a, i64 %b) { ; CHECK-LABEL: @neg_max_sub_ugt_sel_swapped_extrause2( -; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i64 [[B:%.*]], [[A:%.*]] -; CHECK-NEXT: [[SUB:%.*]] = sub i64 [[B]], [[A]] -; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i64 0, i64 [[SUB]] +; CHECK-NEXT: [[SUB:%.*]] = sub i64 [[B:%.*]], [[A:%.*]] +; CHECK-NEXT: [[TMP1:%.*]] = call i64 @llvm.usub.sat.i64(i64 [[A]], i64 [[B]]) +; CHECK-NEXT: [[TMP2:%.*]] = sub i64 0, [[TMP1]] ; CHECK-NEXT: call void @use(i64 [[SUB]]) -; CHECK-NEXT: ret i64 [[SEL]] +; CHECK-NEXT: ret i64 [[TMP2]] ; %cmp = icmp ugt i64 %b, %a %sub = sub i64 %b, %a |
