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[InstCombine] Preserve profile branch weights when folding logical booleans #161293

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Merged
merged 1 commit into from
Oct 6, 2025
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[InstCombine] Preserve profile branch weights when folding logical booleans #161293

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11 changes: 7 additions & 4 deletions llvm/include/llvm/IR/IRBuilder.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1722,16 +1722,19 @@ class IRBuilderBase {
return Insert(BinOp, Name);
}

Value *CreateLogicalAnd(Value *Cond1, Value *Cond2, const Twine &Name = "") {
Value *CreateLogicalAnd(Value *Cond1, Value *Cond2, const Twine &Name = "",
Instruction *MDFrom = nullptr) {
assert(Cond2->getType()->isIntOrIntVectorTy(1));
return CreateSelect(Cond1, Cond2,
ConstantInt::getNullValue(Cond2->getType()), Name);
ConstantInt::getNullValue(Cond2->getType()), Name,
MDFrom);
}

Value *CreateLogicalOr(Value *Cond1, Value *Cond2, const Twine &Name = "") {
Value *CreateLogicalOr(Value *Cond1, Value *Cond2, const Twine &Name = "",
Instruction *MDFrom = nullptr) {
assert(Cond2->getType()->isIntOrIntVectorTy(1));
return CreateSelect(Cond1, ConstantInt::getAllOnesValue(Cond2->getType()),
Cond2, Name);
Cond2, Name, MDFrom);
}

Value *CreateLogicalOp(Instruction::BinaryOps Opc, Value *Cond1, Value *Cond2,
Expand Down
10 changes: 8 additions & 2 deletions llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
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Expand Up @@ -3356,7 +3356,10 @@ Instruction *InstCombinerImpl::foldSelectOfBools(SelectInst &SI) {
impliesPoisonOrCond(FalseVal, B, /*Expected=*/false)) {
// (A || B) || C --> A || (B | C)
return replaceInstUsesWith(
SI, Builder.CreateLogicalOr(A, Builder.CreateOr(B, FalseVal)));
SI, Builder.CreateLogicalOr(A, Builder.CreateOr(B, FalseVal), "",
ProfcheckDisableMetadataFixes
? nullptr
: cast<SelectInst>(CondVal)));
}

// (A && B) || (C && B) --> (A || C) && B
Expand Down Expand Up @@ -3398,7 +3401,10 @@ Instruction *InstCombinerImpl::foldSelectOfBools(SelectInst &SI) {
impliesPoisonOrCond(TrueVal, B, /*Expected=*/true)) {
// (A && B) && C --> A && (B & C)
return replaceInstUsesWith(
SI, Builder.CreateLogicalAnd(A, Builder.CreateAnd(B, TrueVal)));
SI, Builder.CreateLogicalAnd(A, Builder.CreateAnd(B, TrueVal), "",
ProfcheckDisableMetadataFixes
? nullptr
: cast<SelectInst>(CondVal)));
}

// (A || B) && (C || B) --> (A && C) || B
Expand Down
27 changes: 18 additions & 9 deletions llvm/test/Transforms/InstCombine/select-safe-bool-transforms.ll
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@@ -1,4 +1,4 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals
; RUN: opt < %s -passes=instcombine -S | FileCheck %s

; TODO: All of these should be optimized to less than or equal to a single
Expand All @@ -7,13 +7,13 @@
; --- (A op B) op' A / (B op A) op' A ---

; (A land B) land A
define i1 @land_land_left1(i1 %A, i1 %B) {
define i1 @land_land_left1(i1 %A, i1 %B) !prof !0 {
; CHECK-LABEL: @land_land_left1(
; CHECK-NEXT: [[C:%.*]] = select i1 [[A:%.*]], i1 [[B:%.*]], i1 false
; CHECK-NEXT: [[C:%.*]] = select i1 [[A:%.*]], i1 [[B:%.*]], i1 false, !prof [[PROF1:![0-9]+]]
; CHECK-NEXT: ret i1 [[C]]
;
%c = select i1 %A, i1 %B, i1 false
%res = select i1 %c, i1 %A, i1 false
%c = select i1 %A, i1 %B, i1 false, !prof !1
%res = select i1 %c, i1 %A, i1 false, !prof !2
ret i1 %res
}
define i1 @land_land_left2(i1 %A, i1 %B) {
Expand Down Expand Up @@ -157,13 +157,13 @@ define i1 @lor_band_left2(i1 %A, i1 %B) {
}

; (A lor B) lor A
define i1 @lor_lor_left1(i1 %A, i1 %B) {
define i1 @lor_lor_left1(i1 %A, i1 %B) !prof !0 {
; CHECK-LABEL: @lor_lor_left1(
; CHECK-NEXT: [[C:%.*]] = select i1 [[A:%.*]], i1 true, i1 [[B:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A:%.*]], i1 true, i1 [[B:%.*]], !prof [[PROF1]]
; CHECK-NEXT: ret i1 [[C]]
;
%c = select i1 %A, i1 true, i1 %B
%res = select i1 %c, i1 true, i1 %A
%c = select i1 %A, i1 true, i1 %B, !prof !1
%res = select i1 %c, i1 true, i1 %A, !prof !2
ret i1 %res
}
define i1 @lor_lor_left2(i1 %A, i1 %B) {
Expand Down Expand Up @@ -506,3 +506,12 @@ define <2 x i1> @PR50500_falseval(<2 x i1> %a, <2 x i1> %b) {
%r = select <2 x i1> %a, <2 x i1> %b, <2 x i1> %s
ret <2 x i1> %r
}

!0 = !{!"function_entry_count", i64 1000}
!1 = !{!"branch_weights", i32 2, i32 3}
!2 = !{!"branch_weights", i32 5, i32 7}

;.
; CHECK: [[META0:![0-9]+]] = !{!"function_entry_count", i64 1000}
; CHECK: [[PROF1]] = !{!"branch_weights", i32 2, i32 3}
;.