[llvm] [BPF] Support wrapping BPF map structs into nested, single field structs (PR #144097)

[Tamir Duberstein via llvm-commits]

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@@ -976,11 +978,23 @@ void BTFDebug::visitMapDefType(const DIType *Ty, uint32_t &TypeId) {
   if (Tag != dwarf::DW_TAG_structure_type || CTy->isForwardDecl())
     return;
 
-  // Visit all struct members to ensure pointee type is visited
+  // Visit all struct members to ensure their types are visited.
   const DINodeArray Elements = CTy->getElements();
   for (const auto *Element : Elements) {
     const auto *MemberType = cast<DIDerivedType>(Element);
-    visitTypeEntry(MemberType->getBaseType());
+    const DIType *MemberBaseType = MemberType->getBaseType();
+
+    // If the member is a composite type, that may indicate the currently
+    // visited composite type is a wrapper, and the member represents the
+    // actual map definition.
+    // In that case, visit the member with `visitMapDefType` instead of
+    // `visitTypeEntry`, treating it specifically as a map definition rather
+    // than as a regular composite type.
+    const auto *MemberCTy = dyn_cast<DICompositeType>(MemberBaseType);
+    if (MemberCTy) {
+      visitMapDefType(MemberBaseType, TypeId);
+    } else
+      visitTypeEntry(MemberBaseType);
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tamird wrote:

I think this suggestion came from the fact that the commit message and/or PR description haven't been updated?

https://github.com/llvm/llvm-project/pull/144097