[InstCombine][profcheck] Preserve profile when folding constant value equivalences #162736
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…e equivalences For transforms of the form: ``` (X == C) && (Y Pred1 X) --> (X == C) && (Y Pred1 C) (X != C) || (Y Pred1 X) --> (X != C) || (Y Pred1 C) ``` we can preserve the profile branch weights of the select statement because the first condition is unchanged. Tracking issue: llvm#147390
llvmbot
added
llvm:instcombine
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@llvm/pr-subscribers-llvm-transforms Author: Alan Zhao (alanzhao1) ChangesFor transforms of the form: we can preserve the profile branch weights of the select statement because the first condition is unchanged. Tracking issue: #147390 Full diff: https://github.com/llvm/llvm-project/pull/162736.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 9b272c4721cbd..3ddf182149e57 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -28,6 +28,10 @@ using namespace PatternMatch;
#define DEBUG_TYPE "instcombine"
+namespace llvm {
+extern cl::opt<bool> ProfcheckDisableMetadataFixes;
+}
+
/// This is the complement of getICmpCode, which turns an opcode and two
/// operands into either a constant true or false, or a brand new ICmp
/// instruction. The sign is passed in to determine which kind of predicate to
@@ -1272,7 +1276,8 @@ Value *InstCombinerImpl::foldEqOfParts(Value *Cmp0, Value *Cmp1, bool IsAnd) {
static Value *foldAndOrOfICmpsWithConstEq(ICmpInst *Cmp0, ICmpInst *Cmp1,
bool IsAnd, bool IsLogical,
InstCombiner::BuilderTy &Builder,
- const SimplifyQuery &Q) {
+ const SimplifyQuery &Q,
+ Instruction &I) {
// Match an equality compare with a non-poison constant as Cmp0.
// Also, give up if the compare can be constant-folded to avoid looping.
CmpPredicate Pred0;
@@ -1306,9 +1311,12 @@ static Value *foldAndOrOfICmpsWithConstEq(ICmpInst *Cmp0, ICmpInst *Cmp1,
return nullptr;
SubstituteCmp = Builder.CreateICmp(Pred1, Y, C);
}
- if (IsLogical)
- return IsAnd ? Builder.CreateLogicalAnd(Cmp0, SubstituteCmp)
- : Builder.CreateLogicalOr(Cmp0, SubstituteCmp);
+ if (IsLogical) {
+ Instruction *MDFrom =
+ ProfcheckDisableMetadataFixes && isa<SelectInst>(I) ? nullptr : &I;
+ return IsAnd ? Builder.CreateLogicalAnd(Cmp0, SubstituteCmp, "", MDFrom)
+ : Builder.CreateLogicalOr(Cmp0, SubstituteCmp, "", MDFrom);
+ }
return Builder.CreateBinOp(IsAnd ? Instruction::And : Instruction::Or, Cmp0,
SubstituteCmp);
}
@@ -3396,13 +3404,13 @@ Value *InstCombinerImpl::foldAndOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
/*IsLogical*/ false, Builder))
return V;
- if (Value *V =
- foldAndOrOfICmpsWithConstEq(LHS, RHS, IsAnd, IsLogical, Builder, Q))
+ if (Value *V = foldAndOrOfICmpsWithConstEq(LHS, RHS, IsAnd, IsLogical,
+ Builder, Q, I))
return V;
// We can convert this case to bitwise and, because both operands are used
// on the LHS, and as such poison from both will propagate.
- if (Value *V = foldAndOrOfICmpsWithConstEq(RHS, LHS, IsAnd,
- /*IsLogical=*/false, Builder, Q)) {
+ if (Value *V = foldAndOrOfICmpsWithConstEq(
+ RHS, LHS, IsAnd, /*IsLogical=*/false, Builder, Q, I)) {
// If RHS is still used, we should drop samesign flag.
if (IsLogical && RHS->hasSameSign() && !RHS->use_empty()) {
RHS->setSameSign(false);
diff --git a/llvm/test/Transforms/InstCombine/select-safe-transforms.ll b/llvm/test/Transforms/InstCombine/select-safe-transforms.ll
index ebea5bf2eadf4..d88eaf8aa9ddc 100644
--- a/llvm/test/Transforms/InstCombine/select-safe-transforms.ll
+++ b/llvm/test/Transforms/InstCombine/select-safe-transforms.ll
@@ -1,8 +1,11 @@
-; 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
declare i1 @gen1()
+;.
+; CHECK: @glb = global i8 0
+;.
define i1 @cond_eq_and(i8 %X, i8 %Y, i8 noundef %C) {
; CHECK-LABEL: @cond_eq_and(
; CHECK-NEXT: [[COND:%.*]] = icmp eq i8 [[X:%.*]], [[C:%.*]]
@@ -16,16 +19,16 @@ define i1 @cond_eq_and(i8 %X, i8 %Y, i8 noundef %C) {
ret i1 %res
}
-define i1 @cond_eq_and_const(i8 %X, i8 %Y) {
+define i1 @cond_eq_and_const(i8 %X, i8 %Y) !prof !0 {
; CHECK-LABEL: @cond_eq_and_const(
; CHECK-NEXT: [[COND:%.*]] = icmp eq i8 [[X:%.*]], 10
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i8 [[Y:%.*]], 10
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND]], i1 [[TMP1]], i1 false
+; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND]], i1 [[TMP1]], i1 false, !prof [[PROF1:![0-9]+]]
; CHECK-NEXT: ret i1 [[RES]]
;
%cond = icmp eq i8 %X, 10
%lhs = icmp ult i8 %X, %Y
- %res = select i1 %cond, i1 %lhs, i1 false
+ %res = select i1 %cond, i1 %lhs, i1 false, !prof !1
ret i1 %res
}
@@ -42,16 +45,16 @@ define i1 @cond_eq_or(i8 %X, i8 %Y, i8 noundef %C) {
ret i1 %res
}
-define i1 @cond_eq_or_const(i8 %X, i8 %Y) {
+define i1 @cond_eq_or_const(i8 %X, i8 %Y) !prof !0 {
; CHECK-LABEL: @cond_eq_or_const(
; CHECK-NEXT: [[COND:%.*]] = icmp ne i8 [[X:%.*]], 10
; CHECK-NEXT: [[TMP1:%.*]] = icmp ugt i8 [[Y:%.*]], 10
-; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND]], i1 true, i1 [[TMP1]]
+; CHECK-NEXT: [[RES:%.*]] = select i1 [[COND]], i1 true, i1 [[TMP1]], !prof [[PROF1]]
; CHECK-NEXT: ret i1 [[RES]]
;
%cond = icmp ne i8 %X, 10
%lhs = icmp ult i8 %X, %Y
- %res = select i1 %cond, i1 true, i1 %lhs
+ %res = select i1 %cond, i1 true, i1 %lhs, !prof !1
ret i1 %res
}
@@ -793,3 +796,10 @@ define <2 x i1> @not_logical_and2(i1 %b, <2 x i32> %a) {
%or = select <2 x i1> %and, <2 x i1> <i1 true, i1 true>, <2 x i1> %implied
ret <2 x i1> %or
}
+
+!0 = !{!"function_entry_count", i64 1000}
+!1 = !{!"branch_weights", i32 2, i32 3}
+;.
+; CHECK: [[META0:![0-9]+]] = !{!"function_entry_count", i64 1000}
+; CHECK: [[PROF1]] = !{!"branch_weights", i32 2, i32 3}
+;.
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mtrofin
approved these changes
Oct 9, 2025
nikic
approved these changes
Oct 9, 2025
boomanaiden154
approved these changes
Oct 9, 2025
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/65/builds/23817 Here is the relevant piece of the build log for the reference |
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/51/builds/25008 Here is the relevant piece of the build log for the reference |
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For transforms of the form:
we can preserve the profile branch weights of the select statement because the first condition is unchanged.
Tracking issue: #147390