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[InstCombine] Canonicalize max(min(X, MinC), MaxC) -> min(max(X, MaxC), MinC) #136665

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Merged
merged 4 commits into from
Apr 23, 2025
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[InstCombine] Canonicalize max(min(X, MinC), MaxC) -> min(max(X, MaxC), MinC) #136665

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986fc2c
pre-commit tests
el-ev Apr 22, 2025
3d13662
[InstCombine] Canonicalize `max(min(X, MinC), MaxC) -> min(max(X, Max…
el-ev Apr 22, 2025
c9ff093
naming
el-ev Apr 22, 2025
c6efe12
add mixed negative test
el-ev Apr 22, 2025
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23 changes: 23 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1924,6 +1924,29 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
}
}

// smax(smin(X, MinC), MaxC) -> smin(smax(X, MaxC), MinC) if MinC s>= MaxC
// umax(umin(X, MinC), MaxC) -> umin(umax(X, MaxC), MinC) if MinC u>= MaxC
const APInt *MinC, *MaxC;
auto CreateCanonicalClampForm = [&](bool IsSigned) {
auto MaxIID = IsSigned ? Intrinsic::smax : Intrinsic::umax;
auto MinIID = IsSigned ? Intrinsic::smin : Intrinsic::umin;
Value *NewMax = Builder.CreateBinaryIntrinsic(
MaxIID, X, ConstantInt::get(X->getType(), *MaxC));
return replaceInstUsesWith(
*II, Builder.CreateBinaryIntrinsic(
MinIID, NewMax, ConstantInt::get(X->getType(), *MinC)));
};
if (IID == Intrinsic::smax &&
match(I0, m_OneUse(m_Intrinsic<Intrinsic::smin>(m_Value(X),
m_APInt(MinC)))) &&
match(I1, m_APInt(MaxC)) && MinC->sgt(*MaxC))
return CreateCanonicalClampForm(true);
if (IID == Intrinsic::umax &&
match(I0, m_OneUse(m_Intrinsic<Intrinsic::umin>(m_Value(X),
m_APInt(MinC)))) &&
match(I1, m_APInt(MaxC)) && MinC->ugt(*MaxC))
return CreateCanonicalClampForm(false);

// umin(i1 X, i1 Y) -> and i1 X, Y
// smax(i1 X, i1 Y) -> and i1 X, Y
if ((IID == Intrinsic::umin || IID == Intrinsic::smax) &&
Expand Down
28 changes: 14 additions & 14 deletions llvm/test/Transforms/InstCombine/clamp-to-minmax.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -83,7 +83,7 @@ define float @clamp_float_fast_unordered_strict_maxmin(float %x) {
; (X <= C1) ? C1 : MIN(X, C2)
define float @clamp_float_fast_unordered_nonstrict_maxmin(float %x) {
; CHECK-LABEL: @clamp_float_fast_unordered_nonstrict_maxmin(
; CHECK-NEXT: [[MIN:%.*]] = call fast float @llvm.minnum.f32(float [[X:%.*]], float 2.550000e+02)
; CHECK-NEXT: [[MIN:%.*]] = call fast float @llvm.minnum.f32(float [[X:%.*]], float 2.550000e+02)
; CHECK-NEXT: [[CMP1:%.*]] = fcmp fast ule float [[X]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP1]], float 1.000000e+00, float [[MIN]]
; CHECK-NEXT: ret float [[R]]
Expand All @@ -98,7 +98,7 @@ define float @clamp_float_fast_unordered_nonstrict_maxmin(float %x) {
; (X > C1) ? C1 : MAX(X, C2)
define float @clamp_float_fast_unordered_strict_minmax(float %x) {
; CHECK-LABEL: @clamp_float_fast_unordered_strict_minmax(
; CHECK-NEXT: [[MAX:%.*]] = call fast float @llvm.maxnum.f32(float [[X:%.*]], float 1.000000e+00)
; CHECK-NEXT: [[MAX:%.*]] = call fast float @llvm.maxnum.f32(float [[X:%.*]], float 1.000000e+00)
; CHECK-NEXT: [[CMP1:%.*]] = fcmp fast ugt float [[X]], 2.550000e+02
; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP1]], float 2.550000e+02, float [[MAX]]
; CHECK-NEXT: ret float [[R]]
Expand All @@ -113,7 +113,7 @@ define float @clamp_float_fast_unordered_strict_minmax(float %x) {
; (X >= C1) ? C1 : MAX(X, C2)
define float @clamp_float_fast_unordered_nonstrict_minmax(float %x) {
; CHECK-LABEL: @clamp_float_fast_unordered_nonstrict_minmax(
; CHECK-NEXT: [[MAX:%.*]] = call fast float @llvm.maxnum.f32(float [[X:%.*]], float 1.000000e+00)
; CHECK-NEXT: [[MAX:%.*]] = call fast float @llvm.maxnum.f32(float [[X:%.*]], float 1.000000e+00)
; CHECK-NEXT: [[CMP1:%.*]] = fcmp fast uge float [[X]], 2.550000e+02
; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP1]], float 2.550000e+02, float [[MAX]]
; CHECK-NEXT: ret float [[R]]
Expand Down Expand Up @@ -147,7 +147,7 @@ define float @clamp_test_1(float %x) {
; Like @clamp_test_1 but HighConst < LowConst
define float @clamp_negative_wrong_const(float %x) {
; CHECK-LABEL: @clamp_negative_wrong_const(
; CHECK-NEXT: [[INNER_SEL:%.*]] = call fast float @llvm.minnum.f32(float [[X:%.*]], float 2.550000e+02)
; CHECK-NEXT: [[INNER_SEL:%.*]] = call fast float @llvm.minnum.f32(float [[X:%.*]], float 2.550000e+02)
; CHECK-NEXT: [[OUTER_CMP:%.*]] = fcmp fast ugt float [[X]], 5.120000e+02
; CHECK-NEXT: [[R:%.*]] = select i1 [[OUTER_CMP]], float [[INNER_SEL]], float 5.120000e+02
; CHECK-NEXT: ret float [[R]]
Expand All @@ -162,7 +162,7 @@ define float @clamp_negative_wrong_const(float %x) {
; Like @clamp_test_1 but both are min
define float @clamp_negative_same_op(float %x) {
; CHECK-LABEL: @clamp_negative_same_op(
; CHECK-NEXT: [[INNER_SEL:%.*]] = call fast float @llvm.minnum.f32(float [[X:%.*]], float 2.550000e+02)
; CHECK-NEXT: [[INNER_SEL:%.*]] = call fast float @llvm.minnum.f32(float [[X:%.*]], float 2.550000e+02)
; CHECK-NEXT: [[OUTER_CMP:%.*]] = fcmp fast ult float [[X]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select i1 [[OUTER_CMP]], float [[INNER_SEL]], float 1.000000e+00
; CHECK-NEXT: ret float [[R]]
Expand Down Expand Up @@ -500,9 +500,9 @@ define float @ui64_clamp_and_cast_to_float(i64 %x) {

define float @mixed_clamp_to_float_1(i32 %x) {
; CHECK-LABEL: @mixed_clamp_to_float_1(
; CHECK-NEXT: [[SI_MIN:%.*]] = call i32 @llvm.smin.i32(i32 [[X:%.*]], i32 255)
; CHECK-NEXT: [[R1:%.*]] = call i32 @llvm.smax.i32(i32 [[SI_MIN]], i32 1)
; CHECK-NEXT: [[R:%.*]] = uitofp nneg i32 [[R1]] to float
; CHECK-NEXT: [[R1:%.*]] = call i32 @llvm.smax.i32(i32 [[SI_MIN:%.*]], i32 1)
; CHECK-NEXT: [[R2:%.*]] = call i32 @llvm.smin.i32(i32 [[R1]], i32 255)
; CHECK-NEXT: [[R:%.*]] = uitofp nneg i32 [[R2]] to float
; CHECK-NEXT: ret float [[R]]
;
%si_min_cmp = icmp sgt i32 %x, 255
Expand Down Expand Up @@ -535,9 +535,9 @@ define i32 @mixed_clamp_to_i32_1(float %x) {

define float @mixed_clamp_to_float_2(i32 %x) {
; CHECK-LABEL: @mixed_clamp_to_float_2(
; CHECK-NEXT: [[SI_MIN:%.*]] = call i32 @llvm.smin.i32(i32 [[X:%.*]], i32 255)
; CHECK-NEXT: [[R1:%.*]] = call i32 @llvm.smax.i32(i32 [[SI_MIN]], i32 1)
; CHECK-NEXT: [[R:%.*]] = uitofp nneg i32 [[R1]] to float
; CHECK-NEXT: [[R1:%.*]] = call i32 @llvm.smax.i32(i32 [[SI_MIN:%.*]], i32 1)
; CHECK-NEXT: [[R2:%.*]] = call i32 @llvm.smin.i32(i32 [[R1]], i32 255)
; CHECK-NEXT: [[R:%.*]] = uitofp nneg i32 [[R2]] to float
; CHECK-NEXT: ret float [[R]]
;
%si_min_cmp = icmp sgt i32 %x, 255
Expand Down Expand Up @@ -568,9 +568,9 @@ define i32 @mixed_clamp_to_i32_2(float %x) {

define <2 x float> @mixed_clamp_to_float_vec(<2 x i32> %x) {
; CHECK-LABEL: @mixed_clamp_to_float_vec(
; CHECK-NEXT: [[SI_MIN:%.*]] = call <2 x i32> @llvm.smin.v2i32(<2 x i32> [[X:%.*]], <2 x i32> splat (i32 255))
; CHECK-NEXT: [[R1:%.*]] = call <2 x i32> @llvm.smax.v2i32(<2 x i32> [[SI_MIN]], <2 x i32> splat (i32 1))
; CHECK-NEXT: [[R:%.*]] = uitofp nneg <2 x i32> [[R1]] to <2 x float>
; CHECK-NEXT: [[R1:%.*]] = call <2 x i32> @llvm.smax.v2i32(<2 x i32> [[SI_MIN:%.*]], <2 x i32> splat (i32 1))
; CHECK-NEXT: [[R2:%.*]] = call <2 x i32> @llvm.smin.v2i32(<2 x i32> [[R1]], <2 x i32> splat (i32 255))
; CHECK-NEXT: [[R:%.*]] = uitofp nneg <2 x i32> [[R2]] to <2 x float>
; CHECK-NEXT: ret <2 x float> [[R]]
;
%si_min_cmp = icmp sgt <2 x i32> %x, <i32 255, i32 255>
Expand Down
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