[Lldb-commits] [PATCH] D40283: lldb: Use the DWARF linkage name when importing C++ methods

[Nelson Elhage via Phabricator via lldb-commits]

nelhage created this revision.
Herald added subscribers: JDevlieghere, aprantl.

When importing C++ methods into clang AST nodes from the DWARF symbol table, preserve the `DW_AT_linkage_name` and use it as the linker ("asm") name for the symbol.

Concretely, this enables `expression` to call into names that use the GNU `abi_tag` extension, and enables lldb to call into code using `std::string` or `std::list` from recent versions of libstdc++, as described in https://bugs.llvm.org/show_bug.cgi?id=35310 . This also seems potentially broadly more robust than relying on the DWARF->clang->codegen pipeline to roundtrip properly, but I'm not immediately aware of any other cases in which it makes a difference.


https://reviews.llvm.org/D40283

Files:
  include/lldb/Symbol/ClangASTContext.h
  source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
  source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
  source/Symbol/ClangASTContext.cpp


Index: source/Symbol/ClangASTContext.cpp
===================================================================
--- source/Symbol/ClangASTContext.cpp
+++ source/Symbol/ClangASTContext.cpp
@@ -7960,7 +7960,7 @@
 }
 
 clang::CXXMethodDecl *ClangASTContext::AddMethodToCXXRecordType(
-    lldb::opaque_compiler_type_t type, const char *name,
+    lldb::opaque_compiler_type_t type, const char *name, const char *mangled_name,
     const CompilerType &method_clang_type, lldb::AccessType access,
     bool is_virtual, bool is_static, bool is_inline, bool is_explicit,
     bool is_attr_used, bool is_artificial) {
@@ -8080,6 +8080,11 @@
   if (is_attr_used)
     cxx_method_decl->addAttr(clang::UsedAttr::CreateImplicit(*getASTContext()));
 
+  if (mangled_name != NULL) {
+    cxx_method_decl->addAttr(
+        clang::AsmLabelAttr::CreateImplicit(*getASTContext(), mangled_name));
+  }
+
   // Populate the method decl with parameter decls
 
   llvm::SmallVector<clang::ParmVarDecl *, 12> params;
Index: source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
===================================================================
--- source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -220,6 +220,7 @@
       bool is_forward_declaration = false;
       DWARFAttributes attributes;
       const char *type_name_cstr = NULL;
+      const char *mangled_name_cstr = NULL;
       ConstString type_name_const_str;
       Type::ResolveState resolve_state = Type::eResolveStateUnresolved;
       uint64_t byte_size = 0;
@@ -1135,9 +1136,8 @@
 
               case DW_AT_linkage_name:
               case DW_AT_MIPS_linkage_name:
-                break; // mangled =
-                       // form_value.AsCString(&dwarf->get_debug_str_data());
-                       // break;
+                mangled_name_cstr = form_value.AsCString();
+                break;
               case DW_AT_type:
                 type_die_form = form_value;
                 break;
@@ -1498,9 +1498,10 @@
                           clang::CXXMethodDecl *cxx_method_decl =
                               m_ast.AddMethodToCXXRecordType(
                                   class_opaque_type.GetOpaqueQualType(),
-                                  type_name_cstr, clang_type, accessibility,
-                                  is_virtual, is_static, is_inline, is_explicit,
-                                  is_attr_used, is_artificial);
+                                  type_name_cstr, mangled_name_cstr, clang_type,
+                                  accessibility, is_virtual, is_static,
+                                  is_inline, is_explicit, is_attr_used,
+                                  is_artificial);
 
                           type_handled = cxx_method_decl != NULL;
 
Index: source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
===================================================================
--- source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
+++ source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
@@ -2165,7 +2165,7 @@
     CXXMethodDecl *method_decl =
         ClangASTContext::GetASTContext(m_ast_context)
             ->AddMethodToCXXRecordType(
-                copied_clang_type.GetOpaqueQualType(), "$__lldb_expr",
+                copied_clang_type.GetOpaqueQualType(), "$__lldb_expr", NULL,
                 method_type, lldb::eAccessPublic, is_virtual, is_static,
                 is_inline, is_explicit, is_attr_used, is_artificial);
 
Index: include/lldb/Symbol/ClangASTContext.h
===================================================================
--- include/lldb/Symbol/ClangASTContext.h
+++ include/lldb/Symbol/ClangASTContext.h
@@ -821,6 +821,7 @@
 
   clang::CXXMethodDecl *
   AddMethodToCXXRecordType(lldb::opaque_compiler_type_t type, const char *name,
+                           const char *mangled_name,
                            const CompilerType &method_type,
                            lldb::AccessType access, bool is_virtual,
                            bool is_static, bool is_inline, bool is_explicit,


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