Improve the arm/aarch64 mapping symbol handling

[tberghammer]

Summary

Improve the arm/aarch64 mapping symbol handling

Change the mapping symbol handling to handle the case when the mapping
symbols are prefixed with an arbitrary prefix. This isn't strictly standard
compliance, but if all symbols in an object file is prefixed with objcopy
then the prefix will be added to the mapping symbol also. We still want to
treat these symbols as mapping symbols to get the correct address class data.

[clayborg]

Looks good.

[sas]

source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

1857 ↗

(On Diff #34432)

Not very important, but maping vs mapping.

lldb/trunk/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

if (m_sections_ap.get())
         }
         else
         {
             unified_section_list = *m_sections_ap;
         }
     }
 }
 
+// Find the arm/aarch64 mapping symbol character in the given symbol name. Maping symbols have the
+// form of "$<char>[.<any>]*". Additionally we recognize cases when the mapping symbol prefixed by
+// an arbitrary string because if a symbol prefix added to each symbol in the object file with
+// objcopy then the mapping symbols are also prefixed.
+static char
+FindArmAarch64MappingSymbol(const char* symbol_name)
+{
+    if (!symbol_name)
+        return '\0';
+
+    const char* dollar_pos = ::strchr(symbol_name, '$');
+    if (!dollar_pos || dollar_pos[1] == '\0')
+        return '\0';
+
+    if (dollar_pos[2] == '\0' || dollar_pos[2] == '.')
+        return dollar_pos[1];
+    return '\0';
+}
+
 // private
 unsigned
 ObjectFileELF::ParseSymbols (Symtab *symtab,
                              user_id_t start_id,
                              SectionList *section_list,
                              const size_t num_symbols,
                              const DataExtractor &symtab_data,
                              const DataExtractor &strtab_data)
for (i = 0; i < num_symbols; ++i)
         int64_t symbol_value_offset = 0;
         uint32_t additional_flags = 0;
 
         ArchSpec arch;
         if (GetArchitecture(arch))
         {
             if (arch.GetMachine() == llvm::Triple::arm)
             {
-                if (symbol.getBinding() == STB_LOCAL && symbol_name && symbol_name[0] == '$')
+                if (symbol.getBinding() == STB_LOCAL)
                 {
-                    // These are reserved for the specification (e.g.: mapping
-                    // symbols). We don't want to add them to the symbol table.
-
+                    char mapping_symbol = FindArmAarch64MappingSymbol(symbol_name);
                     if (symbol_type == eSymbolTypeCode)
                     {
-                        llvm::StringRef symbol_name_ref(symbol_name);
-                        if (symbol_name_ref == "$a" || symbol_name_ref.startswith("$a."))
+                        switch (mapping_symbol)
                         {
+                            case 'a':
                                 // $a[.<any>]* - marks an ARM instruction sequence
                                 m_address_class_map[symbol.st_value] = eAddressClassCode;
-                        }
-                        else if (symbol_name_ref == "$b" || symbol_name_ref.startswith("$b.") ||
-                                 symbol_name_ref == "$t" || symbol_name_ref.startswith("$t."))
-                        {
+                                break;
+                            case 'b':
+                            case 't':
                                 // $b[.<any>]* - marks a THUMB BL instruction sequence
                                 // $t[.<any>]* - marks a THUMB instruction sequence
                                 m_address_class_map[symbol.st_value] = eAddressClassCodeAlternateISA;
-                        }
-                        else if (symbol_name_ref == "$d" || symbol_name_ref.startswith("$d."))
-                        {
+                                break;
+                            case 'd':
                                 // $d[.<any>]* - marks a data item sequence (e.g. lit pool)
                                 m_address_class_map[symbol.st_value] = eAddressClassData;
+                                break;
                         }
                     }
+                    if (mapping_symbol)
                         continue;
                 }
             }
             else if (arch.GetMachine() == llvm::Triple::aarch64)
             {
-                if (symbol.getBinding() == STB_LOCAL && symbol_name && symbol_name[0] == '$')
+                if (symbol.getBinding() == STB_LOCAL)
                 {
-                    // These are reserved for the specification (e.g.: mapping
-                    // symbols). We don't want to add them to the symbol table.
-
+                    char mapping_symbol = FindArmAarch64MappingSymbol(symbol_name);
                     if (symbol_type == eSymbolTypeCode)
                     {
-                        llvm::StringRef symbol_name_ref(symbol_name);
-                        if (symbol_name_ref == "$x" || symbol_name_ref.startswith("$x."))
+                        switch (mapping_symbol)
                         {
+                            case 'x':
                                 // $x[.<any>]* - marks an A64 instruction sequence
                                 m_address_class_map[symbol.st_value] = eAddressClassCode;
-                        }
-                        else if (symbol_name_ref == "$d" || symbol_name_ref.startswith("$d."))
-                        {
+                                break;
+                            case 'd':
                                 // $d[.<any>]* - marks a data item sequence (e.g. lit pool)
                                 m_address_class_map[symbol.st_value] = eAddressClassData;
+                                break;
                         }
                     }
-
+                    if (mapping_symbol)
                         continue;
                 }
             }
 
             if (arch.GetMachine() == llvm::Triple::arm)
             {
                 if (symbol_type == eSymbolTypeCode)
                 {
                     if (symbol.st_value & 1)