[lldb] Preserve original symbol of Mangled function names

[kastiglione]

Fixes a bug that surfaces in frame recognizers.

Details about the bug:

A new frame recognizer is configured to match a specific symbol (swift_willThrow). This is an extern "C" symbol defined in a C++ source file. When Swift is built with debug info, the function ParseFunctionFromDWARF will use the debug info to construct a function name that looks like a C++ declaration (::swift_willThrow(void *, SwiftError**)). The Mangled instance will have this string as its m_demangled field, and have no string for its m_mangled field.

The result is the frame recognizer would not match the symbol to the name (swift_willThrow != ::swift_willThrow(void *, SwiftError**).

By changing ParseFunctionFromDWARF to assign both a demangled name and a mangled, frame recognizers can successfully match symbols in this configuration.

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Dave Lee (kastiglione)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/152201.diff

1 Files Affected:

• (modified) lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp (+3-1)

diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
index 4c6c3054ba179..a429ea848b7f7 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -2509,7 +2509,9 @@ Function *DWARFASTParserClang::ParseFunctionFromDWARF(
       // If the mangled name is not present in the DWARF, generate the
       // demangled name using the decl context. We skip if the function is
       // "main" as its name is never mangled.
-      func_name.SetValue(ConstructDemangledNameFromDWARF(die));
+      func_name.SetDemangledName(ConstructDemangledNameFromDWARF(die));
+      // Ensure symbol is preserved (as the mangled name).
+      func_name.SetMangledName(ConstString(name));
     } else
       func_name.SetValue(ConstString(name));
 

[github-actions]

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