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[profcheck][InstCombine] Preserve branch weights in logical identities #165810

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Merged
merged 4 commits into from
Nov 3, 2025
Merged

[profcheck][InstCombine] Preserve branch weights in logical identities #165810

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d2e9a89
[profcheck][InstCombine] Preserve branch weights in logical identities
alanzhao1 Oct 31, 2025
3a8ee93
initialize variables to nullptr to silence a warning
alanzhao1 Oct 31, 2025
4a250ba
fix test failures
alanzhao1 Oct 31, 2025
213ab45
nit, next prime is 13 not 17
alanzhao1 Oct 31, 2025
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29 changes: 29 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3599,6 +3599,21 @@ Instruction *InstCombinerImpl::foldSelectOfBools(SelectInst &SI) {
m_Not(m_Specific(SelCond->getTrueValue())));
if (MayNeedFreeze)
C = Builder.CreateFreeze(C);
if (!ProfcheckDisableMetadataFixes) {
Value *C2 = nullptr, *A2 = nullptr, *B2 = nullptr;
if (match(CondVal, m_LogicalAnd(m_Specific(C), m_Value(A2))) &&
SelCond) {
return SelectInst::Create(C, A, B, "", nullptr, SelCond);
} else if (match(FalseVal,
m_LogicalAnd(m_Not(m_Value(C2)), m_Value(B2))) &&
SelFVal) {
SelectInst *NewSI = SelectInst::Create(C, A, B, "", nullptr, SelFVal);
NewSI->swapProfMetadata();
return NewSI;
} else {
return createSelectInstWithUnknownProfile(C, A, B);
}
}
return SelectInst::Create(C, A, B);
}

Expand All @@ -3615,6 +3630,20 @@ Instruction *InstCombinerImpl::foldSelectOfBools(SelectInst &SI) {
m_Not(m_Specific(SelFVal->getTrueValue())));
if (MayNeedFreeze)
C = Builder.CreateFreeze(C);
if (!ProfcheckDisableMetadataFixes) {
Value *C2 = nullptr, *A2 = nullptr, *B2 = nullptr;
if (match(CondVal, m_LogicalAnd(m_Not(m_Value(C2)), m_Value(A2))) &&
SelCond) {
SelectInst *NewSI = SelectInst::Create(C, B, A, "", nullptr, SelCond);
NewSI->swapProfMetadata();
return NewSI;
} else if (match(FalseVal, m_LogicalAnd(m_Specific(C), m_Value(B2))) &&
SelFVal) {
return SelectInst::Create(C, B, A, "", nullptr, SelFVal);
} else {
return createSelectInstWithUnknownProfile(C, B, A);
}
}
return SelectInst::Create(C, B, A);
}
}
Expand Down
51 changes: 27 additions & 24 deletions llvm/test/Transforms/InstCombine/select-safe-transforms.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -256,27 +256,27 @@ define <2 x i1> @not_logical_or2(i1 %b, <2 x i32> %a) {
ret <2 x i1> %and
}

define i1 @bools_logical_commute0(i1 %a, i1 %b, i1 %c) {
define i1 @bools_logical_commute0(i1 %a, i1 %b, i1 %c) !prof !0 {
; CHECK-LABEL: @bools_logical_commute0(
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[B:%.*]], i1 [[A:%.*]]
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[B:%.*]], i1 [[A:%.*]], !prof [[PROF2]]
; CHECK-NEXT: ret i1 [[OR]]
;
%not = xor i1 %c, -1
%and1 = select i1 %not, i1 %a, i1 false
%and2 = select i1 %c, i1 %b, i1 false
%or = select i1 %and1, i1 true, i1 %and2
%and1 = select i1 %not, i1 %a, i1 false, !prof!1
%and2 = select i1 %c, i1 %b, i1 false, !prof !2
%or = select i1 %and1, i1 true, i1 %and2, !prof !3
ret i1 %or
}

define i1 @bools_logical_commute0_and1(i1 %a, i1 %b, i1 %c) {
define i1 @bools_logical_commute0_and1(i1 %a, i1 %b, i1 %c) !prof !0 {
; CHECK-LABEL: @bools_logical_commute0_and1(
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[B:%.*]], i1 [[A:%.*]]
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[B:%.*]], i1 [[A:%.*]], !prof [[PROF1]]
; CHECK-NEXT: ret i1 [[OR]]
;
%not = xor i1 %c, -1
%and1 = and i1 %not, %a
%and2 = select i1 %c, i1 %b, i1 false
%or = select i1 %and1, i1 true, i1 %and2
%and2 = select i1 %c, i1 %b, i1 false, !prof !1
%or = select i1 %and1, i1 true, i1 %and2, !prof !2
ret i1 %or
}

Expand All @@ -292,15 +292,15 @@ define i1 @bools_logical_commute0_and2(i1 %a, i1 %b, i1 %c) {
ret i1 %or
}

define i1 @bools_logical_commute0_and1_and2(i1 %a, i1 %b, i1 %c) {
define i1 @bools_logical_commute0_and1_and2(i1 %a, i1 %b, i1 %c) !prof !0 {
; CHECK-LABEL: @bools_logical_commute0_and1_and2(
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[B:%.*]], i1 [[A:%.*]]
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[B:%.*]], i1 [[A:%.*]], !prof [[PROF3:![0-9]+]]
; CHECK-NEXT: ret i1 [[OR]]
;
%not = xor i1 %c, -1
%and1 = and i1 %not, %a
%and2 = and i1 %c, %b
%or = select i1 %and1, i1 true, i1 %and2
%or = select i1 %and1, i1 true, i1 %and2, !prof !1
ret i1 %or
}

Expand Down Expand Up @@ -457,27 +457,27 @@ define i1 @bools_logical_commute3_and1_and2(i1 %b, i1 %c) {
ret i1 %or
}

define i1 @bools2_logical_commute0(i1 %a, i1 %b, i1 %c) {
define i1 @bools2_logical_commute0(i1 %a, i1 %b, i1 %c) !prof !0 {
; CHECK-LABEL: @bools2_logical_commute0(
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[A:%.*]], i1 [[B:%.*]]
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[A:%.*]], i1 [[B:%.*]], !prof [[PROF1]]
; CHECK-NEXT: ret i1 [[OR]]
;
%not = xor i1 %c, -1
%and1 = select i1 %c, i1 %a, i1 false
%and2 = select i1 %not, i1 %b, i1 false
%or = select i1 %and1, i1 true, i1 %and2
%and1 = select i1 %c, i1 %a, i1 false, !prof !1
%and2 = select i1 %not, i1 %b, i1 false, !prof !2
%or = select i1 %and1, i1 true, i1 %and2, !prof !3
ret i1 %or
}

define i1 @bools2_logical_commute0_and1(i1 %a, i1 %b, i1 %c) {
define i1 @bools2_logical_commute0_and1(i1 %a, i1 %b, i1 %c) !prof !0 {
; CHECK-LABEL: @bools2_logical_commute0_and1(
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[A:%.*]], i1 [[B:%.*]]
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[A:%.*]], i1 [[B:%.*]], !prof [[PROF2]]
; CHECK-NEXT: ret i1 [[OR]]
;
%not = xor i1 %c, -1
%and1 = and i1 %c, %a
%and2 = select i1 %not, i1 %b, i1 false
%or = select i1 %and1, i1 true, i1 %and2
%and2 = select i1 %not, i1 %b, i1 false, !prof !1
%or = select i1 %and1, i1 true, i1 %and2, !prof !2
ret i1 %or
}

Expand All @@ -493,15 +493,15 @@ define i1 @bools2_logical_commute0_and2(i1 %a, i1 %b, i1 %c) {
ret i1 %or
}

define i1 @bools2_logical_commute0_and1_and2(i1 %a, i1 %b, i1 %c) {
define i1 @bools2_logical_commute0_and1_and2(i1 %a, i1 %b, i1 %c) !prof !0 {
; CHECK-LABEL: @bools2_logical_commute0_and1_and2(
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[A:%.*]], i1 [[B:%.*]]
; CHECK-NEXT: [[OR:%.*]] = select i1 [[C:%.*]], i1 [[A:%.*]], i1 [[B:%.*]], !prof [[PROF3]]
; CHECK-NEXT: ret i1 [[OR]]
;
%not = xor i1 %c, -1
%and1 = and i1 %c, %a
%and2 = and i1 %not, %b
%or = select i1 %and1, i1 true, i1 %and2
%or = select i1 %and1, i1 true, i1 %and2, !prof !1
ret i1 %or
}

Expand Down Expand Up @@ -799,8 +799,11 @@ define <2 x i1> @not_logical_and2(i1 %b, <2 x i32> %a) {

!0 = !{!"function_entry_count", i64 1000}
!1 = !{!"branch_weights", i32 2, i32 3}
!2 = !{!"branch_weights", i32 5, i32 7}
!3 = !{!"branch_weights", i32 11, i32 13}
;.
; CHECK: [[META0:![0-9]+]] = !{!"function_entry_count", i64 1000}
; CHECK: [[PROF1]] = !{!"branch_weights", i32 2, i32 3}
; CHECK: [[PROF2]] = !{!"branch_weights", i32 3, i32 2}
; CHECK: [[PROF3]] = !{!"unknown", !"instcombine"}
;.
1 change: 0 additions & 1 deletion llvm/utils/profcheck-xfail.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -913,7 +913,6 @@ Transforms/InstCombine/select_frexp.ll
Transforms/InstCombine/select.ll
Transforms/InstCombine/select-min-max.ll
Transforms/InstCombine/select-of-symmetric-selects.ll
Transforms/InstCombine/select-safe-transforms.ll
Transforms/InstCombine/select-select.ll
Transforms/InstCombine/select-with-extreme-eq-cond.ll
Transforms/InstCombine/shift.ll
Expand Down