https://github.com/mtrofin updated
https://github.com/llvm/llvm-project/pull/154635
>From 15b033f3c0542ae3d7cd53f7e9c65b3d3e31290f Mon Sep 17 00:00:00 2001
From: Mircea Trofin <mtro...@google.com>
Date: Wed, 20 Aug 2025 15:04:49 -0700
Subject: [PATCH] [Local] preserve `MD_prof` in `hoistAllInstructionsInto`
---
llvm/include/llvm/Transforms/Utils/Local.h | 1 +
llvm/lib/Transforms/Utils/Local.cpp | 14 ++++++++++---
.../Transforms/SimplifyCFG/PhiBlockMerge.ll | 21 ++++++++++++-------
3 files changed, 26 insertions(+), 10 deletions(-)
diff --git a/llvm/include/llvm/Transforms/Utils/Local.h
b/llvm/include/llvm/Transforms/Utils/Local.h
index 3f5f4278a2766..605f8d6a19ebe 100644
--- a/llvm/include/llvm/Transforms/Utils/Local.h
+++ b/llvm/include/llvm/Transforms/Utils/Local.h
@@ -498,6 +498,7 @@ LLVM_ABI void dropDebugUsers(Instruction &I);
///
/// The moved instructions receive the insertion point debug location values
/// (DILocations) and their debug intrinsic instructions are removed.
+/// Selects and indirect calls keep their MD_prof metadata.
LLVM_ABI void hoistAllInstructionsInto(BasicBlock *DomBlock,
Instruction *InsertPt, BasicBlock *BB);
diff --git a/llvm/lib/Transforms/Utils/Local.cpp
b/llvm/lib/Transforms/Utils/Local.cpp
index ac344904f90f0..ad796f8605de0 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -116,6 +116,8 @@ static cl::opt<unsigned>
MaxPhiEntriesIncreaseAfterRemovingEmptyBlock(
cl::desc("Stop removing an empty block if removing it will introduce more "
"than this number of phi entries in its successor"));
+extern cl::opt<bool> ProfcheckDisableMetadataFixes;
+
// Max recursion depth for collectBitParts used when detecting bswap and
// bitreverse idioms.
static const unsigned BitPartRecursionMaxDepth = 48;
@@ -3342,8 +3344,11 @@ void llvm::hoistAllInstructionsInto(BasicBlock
*DomBlock, Instruction *InsertPt,
// retain their original debug locations (DILocations) and debug intrinsic
// instructions.
//
- // Doing so would degrade the debugging experience and adversely affect the
- // accuracy of profiling information.
+ // Doing so would degrade the debugging experience.
+ //
+ // FIXME: Issue #152767: debug info should also be the same as the
+ // original branch, **if** the user explicitly indicated that (for sampling
+ // PGO)
//
// Currently, when hoisting the instructions, we take the following actions:
// - Remove their debug intrinsic instructions.
@@ -3362,7 +3367,10 @@ void llvm::hoistAllInstructionsInto(BasicBlock
*DomBlock, Instruction *InsertPt,
for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE;) {
Instruction *I = &*II;
- I->dropUBImplyingAttrsAndMetadata();
+ if (ProfcheckDisableMetadataFixes)
+ I->dropUBImplyingAttrsAndMetadata();
+ else
+ I->dropUBImplyingAttrsAndMetadata({LLVMContext::MD_prof});
if (I->isUsedByMetadata())
dropDebugUsers(*I);
// RemoveDIs: drop debug-info too as the following code does.
diff --git a/llvm/test/Transforms/SimplifyCFG/PhiBlockMerge.ll
b/llvm/test/Transforms/SimplifyCFG/PhiBlockMerge.ll
index 2c5889a981db2..08397b5755a3f 100644
--- a/llvm/test/Transforms/SimplifyCFG/PhiBlockMerge.ll
+++ b/llvm/test/Transforms/SimplifyCFG/PhiBlockMerge.ll
@@ -1,20 +1,21 @@
-; NOTE: Assertions have been autogenerated by update_test_checks.py
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
UTC_ARGS: --check-globals all --version 5
; Test merging of blocks that only have PHI nodes in them
;
; RUN: opt < %s -passes=simplifycfg
-simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
;
define i32 @test(i1 %a, i1 %b) {
-; CHECK-LABEL: @test(
-; CHECK: M:
-; CHECK-NEXT: [[DOT:%.*]] = select i1 %b, i32 0, i32 1
-; CHECK-NEXT: [[W:%.*]] = select i1 %a, i32 2, i32 [[DOT]]
+; CHECK-LABEL: define i32 @test(
+; CHECK-SAME: i1 [[A:%.*]], i1 [[B:%.*]]) {
+; CHECK-NEXT: [[M:.*:]]
+; CHECK-NEXT: [[SPEC_SELECT:%.*]] = select i1 [[B]], i32 0, i32 1, !prof
[[PROF0:![0-9]+]]
+; CHECK-NEXT: [[W:%.*]] = select i1 [[A]], i32 2, i32 [[SPEC_SELECT]],
!prof [[PROF1:![0-9]+]]
; CHECK-NEXT: [[R:%.*]] = add i32 [[W]], 1
; CHECK-NEXT: ret i32 [[R]]
;
- br i1 %a, label %M, label %O
+ br i1 %a, label %M, label %O, !prof !0
O: ; preds = %0
- br i1 %b, label %N, label %Q
+ br i1 %b, label %N, label %Q, !prof !1
Q: ; preds = %O
br label %N
N: ; preds = %Q, %O
@@ -27,3 +28,9 @@ M: ; preds = %N, %0
ret i32 %R
}
+!0 = !{!"branch_weights", i32 11, i32 7}
+!1 = !{!"branch_weights", i32 3, i32 5}
+;.
+; CHECK: [[PROF0]] = !{!"branch_weights", i32 3, i32 5}
+; CHECK: [[PROF1]] = !{!"branch_weights", i32 11, i32 7}
+;.
_______________________________________________
llvm-branch-commits mailing list
llvm-branch-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
