[Lldb-commits] [lldb] [LLDB][NativePDB] Use undecorated name for types if UniqueName isn't mangled (PR #152114)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lldb

Author: nerix (Nerixyz)

<details>
<summary>Changes</summary>

Languages other than C/C++ don't necessarily emit mangled names in the  `UniqueName` field of type records. Rust specifically emits a unique ID that doesn't contain the name.

For example, `(i32, i32)` is emitted as

```llvm
!266 = !DICompositeType(
  tag: DW_TAG_structure_type, name: "tuple$<i32,i32>", file: !9, size: 64, align: 32,
  elements: !267, templateParams: !17, identifier: "19122721b0632fe96c0dd37477674472"
)
```

which results in

```
  0x1091 | LF_STRUCTURE [size = 72, hash = 0x1AC67] `tuple$<i32,i32>`
           unique name: `19122721b0632fe96c0dd37477674472`
           vtable: <no type>, base list: <no type>, field list: 0x1090
           options: has unique name, sizeof 8
```

In C++ with Clang and MSVC, a structure similar to this would result in
```
   0x136F | LF_STRUCTURE [size = 44, hash = 0x30BE2] `MyTuple`
            unique name: `.?AUMyTuple@@`
            vtable: <no type>, base list: <no type>, field list: 0x136E
            options: has unique name, sizeof 8
```

With this PR, if a `UniqueName` is encountered that couldn't be parsed, it will fall back to using the undecorated (→ do the same as if the unique name is empty/unavailable).

I'm not sure how to test this. Maybe compiling the LLVM IR that rustc emits?

Fixes #<!-- -->152051.

---
Full diff: https://github.com/llvm/llvm-project/pull/152114.diff


2 Files Affected:

- (modified) lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp (+1-1) 
- (modified) lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp (+3-7) 


``````````diff
diff --git a/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp b/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
index 8137622842253..36950c00f9e7f 100644
--- a/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
+++ b/lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
@@ -178,7 +178,7 @@ PdbAstBuilder::CreateDeclInfoForType(const TagRecord &record, TypeIndex ti) {
   std::string_view sv(record.UniqueName.begin(), record.UniqueName.size());
   llvm::ms_demangle::TagTypeNode *ttn = demangler.parseTagUniqueName(sv);
   if (demangler.Error)
-    return {m_clang.GetTranslationUnitDecl(), std::string(record.UniqueName)};
+    return CreateDeclInfoForUndecoratedName(record.Name);
 
   llvm::ms_demangle::IdentifierNode *idn =
       ttn->QualifiedName->getUnqualifiedIdentifier();
diff --git a/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp b/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
index 7af53e16ce9d5..24b80c13a10d8 100644
--- a/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
+++ b/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
@@ -618,18 +618,14 @@ lldb::TypeSP SymbolFileNativePDB::CreateSimpleType(TypeIndex ti,
 }
 
 static std::string GetUnqualifiedTypeName(const TagRecord &record) {
-  if (!record.hasUniqueName()) {
-    MSVCUndecoratedNameParser parser(record.Name);
-    llvm::ArrayRef<MSVCUndecoratedNameSpecifier> specs = parser.GetSpecifiers();
-
-    return std::string(specs.back().GetBaseName());
-  }
+  if (!record.hasUniqueName())
+    return std::string(MSVCUndecoratedNameParser::DropScope(record.Name));
 
   llvm::ms_demangle::Demangler demangler;
   std::string_view sv(record.UniqueName.begin(), record.UniqueName.size());
   llvm::ms_demangle::TagTypeNode *ttn = demangler.parseTagUniqueName(sv);
   if (demangler.Error)
-    return std::string(record.Name);
+    return std::string(MSVCUndecoratedNameParser::DropScope(record.Name));
 
   llvm::ms_demangle::IdentifierNode *idn =
       ttn->QualifiedName->getUnqualifiedIdentifier();

``````````

</details>


https://github.com/llvm/llvm-project/pull/152114