Author: Felipe de Azevedo Piovezan Date: 2023-07-13T08:27:29-04:00 New Revision: 85c2e420c87c20af6a7e1699a7317d8adc51b5ff
URL: https://github.com/llvm/llvm-project/commit/85c2e420c87c20af6a7e1699a7317d8adc51b5ff DIFF: https://github.com/llvm/llvm-project/commit/85c2e420c87c20af6a7e1699a7317d8adc51b5ff.diff LOG: [lldb][NFC] Factor out code linking OSO addr of uninitialized GVs This code was introduced in 2fc93eabf7e132abd51d0ea0ad599beb3fa44334. In order to improve readability of ParseVariableDIE, we move this code into a helper function. The issue this code attempted to address was fixed between Clangs 9 and 11; as such, if we ever want to delete this code, it is a lot easier to do so after the refactor. Differential Revision: https://reviews.llvm.org/D155100 Added: Modified: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp Removed: ################################################################################ diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp index 94baa5553c4bb3..6e5482dba9d262 100644 --- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp +++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp @@ -3323,6 +3323,38 @@ GetExprListFromAtConstValue(DWARFFormValue form_value, ModuleSP module, return DWARFExpressionList(module, DWARFExpression(), die.GetCU()); } +/// Global variables that are not initialized may have their address set to +/// zero. Since multiple variables may have this address, we cannot apply the +/// OSO relink address approach we normally use. +/// However, the executable will have a matching symbol with a good address; +/// this function attempts to find the correct address by looking into the +/// executable's symbol table. If it succeeds, the expr_list is updated with +/// the new address and the executable's symbol is returned. +static Symbol *fixupExternalAddrZeroVariable( + SymbolFileDWARFDebugMap &debug_map_symfile, llvm::StringRef name, + DWARFExpressionList &expr_list, const DWARFDIE &die) { + ObjectFile *debug_map_objfile = debug_map_symfile.GetObjectFile(); + if (!debug_map_objfile) + return nullptr; + + Symtab *debug_map_symtab = debug_map_objfile->GetSymtab(); + if (!debug_map_symtab) + return nullptr; + Symbol *exe_symbol = debug_map_symtab->FindFirstSymbolWithNameAndType( + ConstString(name), eSymbolTypeData, Symtab::eDebugYes, + Symtab::eVisibilityExtern); + if (!exe_symbol || !exe_symbol->ValueIsAddress()) + return nullptr; + const addr_t exe_file_addr = exe_symbol->GetAddressRef().GetFileAddress(); + if (exe_file_addr == LLDB_INVALID_ADDRESS) + return nullptr; + + DWARFExpression *location = expr_list.GetMutableExpressionAtAddress(); + if (location->Update_DW_OP_addr(die.GetCU(), exe_file_addr)) + return exe_symbol; + return nullptr; +} + VariableSP SymbolFileDWARF::ParseVariableDIE(const SymbolContext &sc, const DWARFDIE &die, const lldb::addr_t func_low_pc) { @@ -3496,49 +3528,14 @@ VariableSP SymbolFileDWARF::ParseVariableDIE(const SymbolContext &sc, scope = eValueTypeVariableStatic; if (debug_map_symfile) { - // When leaving the DWARF in the .o files on darwin, when we have a - // global variable that wasn't initialized, the .o file might not - // have allocated a virtual address for the global variable. In - // this case it will have created a symbol for the global variable - // that is undefined/data and external and the value will be the - // byte size of the variable. When we do the address map in - // SymbolFileDWARFDebugMap we rely on having an address, we need to - // do some magic here so we can get the correct address for our - // global variable. The address for all of these entries will be - // zero, and there will be an undefined symbol in this object file, - // and the executable will have a matching symbol with a good - // address. So here we dig up the correct address and replace it in - // the location for the variable, and set the variable's symbol - // context scope to be that of the main executable so the file - // address will resolve correctly. bool linked_oso_file_addr = false; + if (is_external && location_DW_OP_addr == 0) { - // we have a possible uninitialized extern global - ConstString const_name(mangled ? mangled : name); - ObjectFile *debug_map_objfile = debug_map_symfile->GetObjectFile(); - if (debug_map_objfile) { - Symtab *debug_map_symtab = debug_map_objfile->GetSymtab(); - if (debug_map_symtab) { - Symbol *exe_symbol = - debug_map_symtab->FindFirstSymbolWithNameAndType( - const_name, eSymbolTypeData, Symtab::eDebugYes, - Symtab::eVisibilityExtern); - if (exe_symbol) { - if (exe_symbol->ValueIsAddress()) { - const addr_t exe_file_addr = - exe_symbol->GetAddressRef().GetFileAddress(); - if (exe_file_addr != LLDB_INVALID_ADDRESS) { - DWARFExpression *location = - location_list.GetMutableExpressionAtAddress(); - if (location->Update_DW_OP_addr(die.GetCU(), - exe_file_addr)) { - linked_oso_file_addr = true; - symbol_context_scope = exe_symbol; - } - } - } - } - } + if (Symbol *exe_symbol = fixupExternalAddrZeroVariable( + *debug_map_symfile, mangled ? mangled : name, location_list, + die)) { + linked_oso_file_addr = true; + symbol_context_scope = exe_symbol; } } _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
