[DebugInfo] Update DebugInfoFinder to take retainedNodes into account

[dzhidzhoev]

Since https://reviews.llvm.org/D144004, DISubprogram's retainedNodes field is used to track DIImportedEntities, in addition to local variables and labels.

However, the corresponding update for DebugInfoFinder, to make it visit DISubprogram's retainedNodes, was missing.
This is the fix for it.

This change is separated from #119001 to simplify it.

[llvmbot]

@llvm/pr-subscribers-debuginfo

@llvm/pr-subscribers-llvm-ir

Author: Vladislav Dzhidzhoev (dzhidzhoev)

Changes

Since https://reviews.llvm.org/D144004, DISubprogram's retainedNodes field is used to track DIImportedEntities, in addition to local variables and labels.

However, the corresponding update for DebugInfoFinder, to make it visit DISubprogram's retainedNodes, was missing.
This is the fix for it.

This change is separated from #119001 to simplify it.

---

Full diff: https://github.com/llvm/llvm-project/pull/140285.diff

3 Files Affected:

• (modified) llvm/include/llvm/IR/DebugInfo.h (+2-1)
• (modified) llvm/lib/IR/DebugInfo.cpp (+22-13)
• (added) llvm/test/DebugInfo/Generic/debuginfofinder-retained-nodes.ll (+38)

diff --git a/llvm/include/llvm/IR/DebugInfo.h b/llvm/include/llvm/IR/DebugInfo.h
index 73f45c3769be4..c47738a6442e6 100644
--- a/llvm/include/llvm/IR/DebugInfo.h
+++ b/llvm/include/llvm/IR/DebugInfo.h
@@ -110,7 +110,7 @@ class DebugInfoFinder {
   void processInstruction(const Module &M, const Instruction &I);
 
   /// Process a DILocalVariable.
-  void processVariable(const Module &M, const DILocalVariable *DVI);
+  void processVariable(DILocalVariable *DVI);
   /// Process debug info location.
   void processLocation(const Module &M, const DILocation *Loc);
   /// Process a DbgRecord (e.g, treat a DbgVariableRecord like a
@@ -127,6 +127,7 @@ class DebugInfoFinder {
   void processCompileUnit(DICompileUnit *CU);
   void processScope(DIScope *Scope);
   void processType(DIType *DT);
+  void processImportedEntity(DIImportedEntity *Import);
   bool addCompileUnit(DICompileUnit *CU);
   bool addGlobalVariable(DIGlobalVariableExpression *DIG);
   bool addScope(DIScope *Scope);
diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index dff9a08c2c8e0..9abde9023d057 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -242,22 +242,14 @@ void DebugInfoFinder::processCompileUnit(DICompileUnit *CU) {
     else
       processSubprogram(cast<DISubprogram>(RT));
   for (auto *Import : CU->getImportedEntities()) {
-    auto *Entity = Import->getEntity();
-    if (auto *T = dyn_cast<DIType>(Entity))
-      processType(T);
-    else if (auto *SP = dyn_cast<DISubprogram>(Entity))
-      processSubprogram(SP);
-    else if (auto *NS = dyn_cast<DINamespace>(Entity))
-      processScope(NS->getScope());
-    else if (auto *M = dyn_cast<DIModule>(Entity))
-      processScope(M->getScope());
+    processImportedEntity(Import);
   }
 }
 
 void DebugInfoFinder::processInstruction(const Module &M,
                                          const Instruction &I) {
   if (auto *DVI = dyn_cast<DbgVariableIntrinsic>(&I))
-    processVariable(M, DVI->getVariable());
+    processVariable(DVI->getVariable());
 
   if (auto DbgLoc = I.getDebugLoc())
     processLocation(M, DbgLoc.get());
@@ -275,7 +267,7 @@ void DebugInfoFinder::processLocation(const Module &M, const DILocation *Loc) {
 
 void DebugInfoFinder::processDbgRecord(const Module &M, const DbgRecord &DR) {
   if (const DbgVariableRecord *DVR = dyn_cast<const DbgVariableRecord>(&DR))
-    processVariable(M, DVR->getVariable());
+    processVariable(DVR->getVariable());
   processLocation(M, DR.getDebugLoc().get());
 }
 
@@ -303,6 +295,18 @@ void DebugInfoFinder::processType(DIType *DT) {
   }
 }
 
+void DebugInfoFinder::processImportedEntity(DIImportedEntity *Import) {
+  auto *Entity = Import->getEntity();
+  if (auto *T = dyn_cast<DIType>(Entity))
+    processType(T);
+  else if (auto *SP = dyn_cast<DISubprogram>(Entity))
+    processSubprogram(SP);
+  else if (auto *NS = dyn_cast<DINamespace>(Entity))
+    processScope(NS->getScope());
+  else if (auto *M = dyn_cast<DIModule>(Entity))
+    processScope(M->getScope());
+}
+
 void DebugInfoFinder::processScope(DIScope *Scope) {
   if (!Scope)
     return;
@@ -350,10 +354,15 @@ void DebugInfoFinder::processSubprogram(DISubprogram *SP) {
       processType(TVal->getType());
     }
   }
+
+  for (auto *N : SP->getRetainedNodes())
+    if (auto *Var = dyn_cast_or_null<DILocalVariable>(N))
+      processVariable(Var);
+    else if (auto *Import = dyn_cast_or_null<DIImportedEntity>(N))
+      processImportedEntity(Import);
 }
 
-void DebugInfoFinder::processVariable(const Module &M,
-                                      const DILocalVariable *DV) {
+void DebugInfoFinder::processVariable(DILocalVariable *DV) {
   if (!NodesSeen.insert(DV).second)
     return;
   processScope(DV->getScope());
diff --git a/llvm/test/DebugInfo/Generic/debuginfofinder-retained-nodes.ll b/llvm/test/DebugInfo/Generic/debuginfofinder-retained-nodes.ll
new file mode 100644
index 0000000000000..f8185c65639d6
--- /dev/null
+++ b/llvm/test/DebugInfo/Generic/debuginfofinder-retained-nodes.ll
@@ -0,0 +1,38 @@
+; RUN: opt -passes='print<module-debuginfo>' -disable-output 2>&1 < %s \
+; RUN:   | FileCheck %s
+
+; This is to track DebugInfoFinder's ability to find the debug info metadata,
+; in particular, properly visit DISubprogram's retainedNodes.
+
+; CHECK: Compile unit: DW_LANG_C_plus_plus from /somewhere/source.cpp
+; CHECK: Subprogram: foo from /somewhere/source.cpp:1 ('_Z3foov')
+; CHECK: Subprogram: bar from /somewhere/source.cpp:5
+; CHECK: Type: T from /somewhere/source.cpp:2 DW_TAG_structure_type
+
+%struct.T = type { i32 }
+
+; Function Attrs: mustprogress noinline nounwind optnone ssp uwtable(sync)
+define noundef i32 @_Z3foov() !dbg !7 {
+entry:
+  ret i32 0
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 21.0.0git", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
+!1 = !DIFile(filename: "source.cpp", directory: "/somewhere")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 8, !"PIC Level", i32 2}
+!6 = !{!"clang version 21.0.0git"}
+!7 = distinct !DISubprogram(name: "foo", linkageName: "_Z3foov", scope: !1, file: !1, line: 1, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !8)
+!8 = !{!9}
+!9 = !DILocalVariable(name: "v", scope: !7, file: !1, line: 8, type: !10)
+!10 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "T", scope: !7, file: !1, line: 2, size: 32, flags: DIFlagTypePassByValue, elements: !11)
+!11 = !{!12, !14}
+!12 = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: !10, file: !1, line: 3, baseType: !13, size: 32)
+!13 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!14 = !DISubprogram(name: "bar", scope: !10, file: !1, line: 5, scopeLine: 5, flags: DIFlagPrototyped | DIFlagStaticMember, spFlags: DISPFlagLocalToUnit)
\ No newline at end of file

[SLTozer]

Change LGTM, but might be a good idea to add a DIImportedEntity to the test as well.

[SLTozer]

Requesting braces for the for block here.

[dzhidzhoev]

Fixed.

[dzhidzhoev]

Change LGTM, but might be a good idea to add a DIImportedEntity to the test as well.

The test case was added. Should I merge it? (Asking since the "approve" button wasn't pressed 🙂 ).