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[ValueTracking] Fix poison propagation in matchFastFloatClamp #144215

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[ValueTracking] Fix poison propagation in matchFastFloatClamp #144215

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2bd37f1
[InstCombine] Add pre-commit tests. NFC.
dtcxzyw Jun 14, 2025
02ff6ba
[ValueTracking] Fix poison propagation in `matchFastFloatClamp`
dtcxzyw Jun 14, 2025
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3 changes: 2 additions & 1 deletion llvm/lib/Analysis/ValueTracking.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8181,7 +8181,8 @@ static SelectPatternResult matchFastFloatClamp(CmpInst::Predicate Pred,
RHS = FalseVal;

const APFloat *FC1;
if (CmpRHS != TrueVal || !match(CmpRHS, m_APFloat(FC1)) || !FC1->isFinite())
if (CmpRHS != TrueVal || !match(CmpRHS, m_APFloat(FC1)) || !FC1->isFinite() ||
!isGuaranteedNotToBePoison(FalseVal))
return {SPF_UNKNOWN, SPNB_NA, false};

const APFloat *FC2;
Expand Down
84 changes: 50 additions & 34 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 @@ -3,63 +3,63 @@
; RUN: opt < %s -passes=instcombine -use-constant-fp-for-fixed-length-splat -use-constant-int-for-fixed-length-splat -S | FileCheck %s

; (X < C1) ? C1 : MIN(X, C2)
define float @clamp_float_fast_ordered_strict_maxmin(float %x) {
define float @clamp_float_fast_ordered_strict_maxmin(float noundef %x) {
; CHECK-LABEL: @clamp_float_fast_ordered_strict_maxmin(
; CHECK-NEXT: [[CMP2:%.*]] = fcmp fast olt float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[CMP2:%.*]] = fcmp olt float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[MIN:%.*]] = select i1 [[CMP2]], float [[X]], float 2.550000e+02
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast oge float [[MIN]], 1.000000e+00
; CHECK-NEXT: [[R1:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MIN]], float 1.000000e+00
; CHECK-NEXT: ret float [[R1]]
;
%cmp2 = fcmp fast olt float %x, 255.0
%cmp2 = fcmp olt float %x, 255.0
%min = select i1 %cmp2, float %x, float 255.0
%cmp1 = fcmp fast olt float %x, 1.0
%r = select i1 %cmp1, float 1.0, float %min
ret float %r
}

; (X <= C1) ? C1 : MIN(X, C2)
define float @clamp_float_fast_ordered_nonstrict_maxmin(float %x) {
define float @clamp_float_fast_ordered_nonstrict_maxmin(float noundef %x) {
; CHECK-LABEL: @clamp_float_fast_ordered_nonstrict_maxmin(
; CHECK-NEXT: [[CMP2:%.*]] = fcmp fast olt float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[CMP2:%.*]] = fcmp olt float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[MIN:%.*]] = select i1 [[CMP2]], float [[X]], float 2.550000e+02
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast oge float [[MIN]], 1.000000e+00
; CHECK-NEXT: [[R1:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MIN]], float 1.000000e+00
; CHECK-NEXT: ret float [[R1]]
;
%cmp2 = fcmp fast olt float %x, 255.0
%cmp2 = fcmp olt float %x, 255.0
%min = select i1 %cmp2, float %x, float 255.0
%cmp1 = fcmp fast ole float %x, 1.0
%r = select i1 %cmp1, float 1.0, float %min
ret float %r
}

; (X > C1) ? C1 : MAX(X, C2)
define float @clamp_float_fast_ordered_strict_minmax(float %x) {
define float @clamp_float_fast_ordered_strict_minmax(float noundef %x) {
; CHECK-LABEL: @clamp_float_fast_ordered_strict_minmax(
; CHECK-NEXT: [[CMP2:%.*]] = fcmp fast ogt float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[CMP2:%.*]] = fcmp ogt float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[MAX:%.*]] = select i1 [[CMP2]], float [[X]], float 1.000000e+00
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast ole float [[MAX]], 2.550000e+02
; CHECK-NEXT: [[R1:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MAX]], float 2.550000e+02
; CHECK-NEXT: ret float [[R1]]
;
%cmp2 = fcmp fast ogt float %x, 1.0
%cmp2 = fcmp ogt float %x, 1.0
%max = select i1 %cmp2, float %x, float 1.0
%cmp1 = fcmp fast ogt float %x, 255.0
%r = select i1 %cmp1, float 255.0, float %max
ret float %r
}

; (X >= C1) ? C1 : MAX(X, C2)
define float @clamp_float_fast_ordered_nonstrict_minmax(float %x) {
define float @clamp_float_fast_ordered_nonstrict_minmax(float noundef %x) {
; CHECK-LABEL: @clamp_float_fast_ordered_nonstrict_minmax(
; CHECK-NEXT: [[CMP2:%.*]] = fcmp fast ogt float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[CMP2:%.*]] = fcmp ogt float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[MAX:%.*]] = select i1 [[CMP2]], float [[X]], float 1.000000e+00
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast ole float [[MAX]], 2.550000e+02
; CHECK-NEXT: [[R1:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MAX]], float 2.550000e+02
; CHECK-NEXT: ret float [[R1]]
;
%cmp2 = fcmp fast ogt float %x, 1.0
%cmp2 = fcmp ogt float %x, 1.0
%max = select i1 %cmp2, float %x, float 1.0
%cmp1 = fcmp fast oge float %x, 255.0
%r = select i1 %cmp1, float 255.0, float %max
Expand All @@ -70,63 +70,63 @@ define float @clamp_float_fast_ordered_nonstrict_minmax(float %x) {
; The same for unordered

; (X < C1) ? C1 : MIN(X, C2)
define float @clamp_float_fast_unordered_strict_maxmin(float %x) {
define float @clamp_float_fast_unordered_strict_maxmin(float noundef %x) {
; CHECK-LABEL: @clamp_float_fast_unordered_strict_maxmin(
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp fast oge float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[MIN:%.*]] = select nnan ninf i1 [[CMP2_INV]], float 2.550000e+02, float [[X]]
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp oge float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[MIN:%.*]] = select i1 [[CMP2_INV]], float 2.550000e+02, float [[X]]
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast oge float [[MIN]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MIN]], float 1.000000e+00
; CHECK-NEXT: ret float [[R]]
;
%cmp2 = fcmp fast ult float %x, 255.0
%cmp2 = fcmp ult float %x, 255.0
%min = select i1 %cmp2, float %x, float 255.0
%cmp1 = fcmp fast ult float %x, 1.0
%r = select i1 %cmp1, float 1.0, float %min
ret float %r
}

; (X <= C1) ? C1 : MIN(X, C2)
define float @clamp_float_fast_unordered_nonstrict_maxmin(float %x) {
define float @clamp_float_fast_unordered_nonstrict_maxmin(float noundef %x) {
; CHECK-LABEL: @clamp_float_fast_unordered_nonstrict_maxmin(
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp fast oge float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[MIN:%.*]] = select nnan ninf i1 [[CMP2_INV]], float 2.550000e+02, float [[X]]
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp oge float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[MIN:%.*]] = select i1 [[CMP2_INV]], float 2.550000e+02, float [[X]]
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast oge float [[MIN]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MIN]], float 1.000000e+00
; CHECK-NEXT: ret float [[R]]
;
%cmp2 = fcmp fast ult float %x, 255.0
%cmp2 = fcmp ult float %x, 255.0
%min = select i1 %cmp2, float %x, float 255.0
%cmp1 = fcmp fast ule float %x, 1.0
%r = select i1 %cmp1, float 1.0, float %min
ret float %r
}

; (X > C1) ? C1 : MAX(X, C2)
define float @clamp_float_fast_unordered_strict_minmax(float %x) {
define float @clamp_float_fast_unordered_strict_minmax(float noundef %x) {
; CHECK-LABEL: @clamp_float_fast_unordered_strict_minmax(
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp fast ole float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[MAX:%.*]] = select nnan ninf i1 [[CMP2_INV]], float 1.000000e+00, float [[X]]
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp ole float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[MAX:%.*]] = select i1 [[CMP2_INV]], float 1.000000e+00, float [[X]]
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast ole float [[MAX]], 2.550000e+02
; CHECK-NEXT: [[R:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MAX]], float 2.550000e+02
; CHECK-NEXT: ret float [[R]]
;
%cmp2 = fcmp fast ugt float %x, 1.0
%cmp2 = fcmp ugt float %x, 1.0
%max = select i1 %cmp2, float %x, float 1.0
%cmp1 = fcmp fast ugt float %x, 255.0
%r = select i1 %cmp1, float 255.0, float %max
ret float %r
}

; (X >= C1) ? C1 : MAX(X, C2)
define float @clamp_float_fast_unordered_nonstrict_minmax(float %x) {
define float @clamp_float_fast_unordered_nonstrict_minmax(float noundef %x) {
; CHECK-LABEL: @clamp_float_fast_unordered_nonstrict_minmax(
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp fast ole float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[MAX:%.*]] = select nnan ninf i1 [[CMP2_INV]], float 1.000000e+00, float [[X]]
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp ole float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[MAX:%.*]] = select i1 [[CMP2_INV]], float 1.000000e+00, float [[X]]
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast ole float [[MAX]], 2.550000e+02
; CHECK-NEXT: [[R:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MAX]], float 2.550000e+02
; CHECK-NEXT: ret float [[R]]
;
%cmp2 = fcmp fast ugt float %x, 1.0
%cmp2 = fcmp ugt float %x, 1.0
%max = select i1 %cmp2, float %x, float 1.0
%cmp1 = fcmp fast uge float %x, 255.0
%r = select i1 %cmp1, float 255.0, float %max
Expand All @@ -136,15 +136,15 @@ define float @clamp_float_fast_unordered_nonstrict_minmax(float %x) {
; Some more checks with fast

; (X > 1.0) ? min(x, 255.0) : 1.0
define float @clamp_test_1(float %x) {
define float @clamp_test_1(float noundef %x) {
; CHECK-LABEL: @clamp_test_1(
; CHECK-NEXT: [[INNER_CMP_INV:%.*]] = fcmp fast oge float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[INNER_SEL:%.*]] = select nnan ninf i1 [[INNER_CMP_INV]], float 2.550000e+02, float [[X]]
; CHECK-NEXT: [[OUTER_CMP:%.*]] = fcmp fast oge float [[INNER_SEL]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select nnan ninf i1 [[OUTER_CMP]], float [[INNER_SEL]], float 1.000000e+00
; CHECK-NEXT: [[INNER_CMP_INV:%.*]] = fcmp oge float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[INNER_SEL:%.*]] = select i1 [[INNER_CMP_INV]], float 2.550000e+02, float [[X]]
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast oge float [[INNER_SEL]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select nnan ninf i1 [[DOTINV]], float [[INNER_SEL]], float 1.000000e+00
; CHECK-NEXT: ret float [[R]]
;
%inner_cmp = fcmp fast ult float %x, 255.0
%inner_cmp = fcmp ult float %x, 255.0
%inner_sel = select i1 %inner_cmp, float %x, float 255.0
%outer_cmp = fcmp fast ugt float %x, 1.0
%r = select i1 %outer_cmp, float %inner_sel, float 1.0
Expand Down Expand Up @@ -185,6 +185,22 @@ define float @clamp_negative_same_op(float %x) {
ret float %r
}

define float @clamp_negative_propagate_poison(float %x) {
; CHECK-LABEL: @clamp_negative_propagate_poison(
; CHECK-NEXT: [[CMP1:%.*]] = fcmp ninf ole float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[MAX:%.*]] = select i1 [[CMP1]], float 1.000000e+00, float [[X]]
; CHECK-NEXT: [[CMP2:%.*]] = fcmp nnan ole float [[X]], 2.550000e+02
; CHECK-NEXT: [[R1:%.*]] = select i1 [[CMP2]], float [[MAX]], float 2.550000e+02
; CHECK-NEXT: ret float [[R1]]
;
%cmp1 = fcmp ninf ole float %x, 1.000000e+00
%max = select i1 %cmp1, float 1.000000e+00, float %x
%cmp2 = fcmp nnan ole float %x, 2.550000e+02
%r = select i1 %cmp2, float %max, float 2.550000e+02
ret float %r
}



; And now without fast.

Expand Down
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