[llvm] [DebugInfo] Limit stripNonLineTableDebugInfo to debug named metadata (PR #225858)

[Fabian Parzefall via llvm-commits]

https://github.com/pzfl updated https://github.com/llvm/llvm-project/pull/225858

>From 17284ca85898ec2bb8f8af7722392b7805b37761 Mon Sep 17 00:00:00 2001
From: Fabian Parzefall <parzefall at meta.com>
Date: Wed, 23 Sep 2026 10:15:45 -0700
Subject: [PATCH] [DebugInfo] Limit stripNonLineTableDebugInfo to debug named
 metadata

stripNonLineTableDebugInfo processes all named metadata nodes in the
module. Since remapping discards null-nodes, this might modify metadata
that is not related to debug info. Limit this to only llvm.dbg.* and
llvm.gcov named metadata. Also, remove a dead loop.
---
 llvm/lib/IR/DebugInfo.cpp                           | 13 +++----------
 .../Util/strip-nonlinetable-debuginfo-cus.ll        |  4 ++++
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index 8a119a98784a6b..881e83a0077c5a 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -954,16 +954,6 @@ void DebugTypeInfoRemoval::traverse(MDNode *N) {
 bool llvm::stripNonLineTableDebugInfo(Module &M) {
   bool Changed = false;
 
-  // Delete non-CU debug info named metadata nodes.
-  for (auto NMI = M.named_metadata_begin(), NME = M.named_metadata_end();
-       NMI != NME;) {
-    NamedMDNode *NMD = &*NMI;
-    ++NMI;
-    // Specifically keep dbg.cu around.
-    if (NMD->getName() == "llvm.dbg.cu")
-      continue;
-  }
-
   // Drop all dbg attachments from global variables.
   for (auto &GV : M.globals())
     GV.eraseMetadata(LLVMContext::MD_dbg);
@@ -1022,6 +1012,9 @@ bool llvm::stripNonLineTableDebugInfo(Module &M) {
   // Create a new llvm.dbg.cu, which is equivalent to the one
   // -gline-tables-only would have created.
   for (auto &NMD : M.named_metadata()) {
+    if (!NMD.getName().starts_with("llvm.dbg.") && NMD.getName() != "llvm.gcov")
+      continue;
+
     SmallVector<MDNode *, 8> Ops;
     for (MDNode *Op : NMD.operands())
       Ops.push_back(remap(Op));
diff --git a/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo-cus.ll b/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo-cus.ll
index 47074048d8769c..6129e8c45d2cba 100644
--- a/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo-cus.ll
+++ b/llvm/test/Transforms/Util/strip-nonlinetable-debuginfo-cus.ll
@@ -2,15 +2,18 @@
 !llvm.dbg.cu = !{!2, !6}
 !llvm.gcov = !{!3}
 !llvm.module.flags = !{!7}
+!llvm.other.md = !{!8}
 
 !1 = !DIFile(filename: "path/to/file", directory: "/path/to/dir")
 ; The first CU is used for the line table, the second one is a module skeleton
 ; and should be stripped.
 ; CHECK: !llvm.dbg.cu = !{![[CU:[0-9]+]]}
+; CHECK: !llvm.other.md = !{![[OTHER:[0-9]+]]}
 ; CHECK: ![[CU]] = distinct !DICompileUnit({{.*}}"abc.debug"{{.*}}LineTablesOnly
 ; CHECK-NOT: retainedTypes:
 ; CHECK-SAME: )
 ; CHECK-NOT: DICompositeType
+; CHECK: ![[OTHER]] = distinct !{null, i32 8}
 !2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang",
                              isOptimized: true, flags: "-O2", runtimeVersion: 2,
                              splitDebugFilename: "abc.debug", emissionKind: FullDebug,
@@ -22,3 +25,4 @@
                              splitDebugFilename: "abc.dwo", emissionKind: FullDebug,
                              dwoId: 1234)
 !7 = !{i32 1, !"Debug Info Version", i32 3}
+!8 = distinct !{null, i32 8}