Author: barsolo2000 Date: 2025-08-27T19:58:08-05:00 New Revision: c2be0351a725c95e3841a8d59ee432f5b205763f
URL: https://github.com/llvm/llvm-project/commit/c2be0351a725c95e3841a8d59ee432f5b205763f DIFF: https://github.com/llvm/llvm-project/commit/c2be0351a725c95e3841a8d59ee432f5b205763f.diff LOG: [LLDB] Omit loading local symbols in LLDB symbol table (#154809) https://discourse.llvm.org/t/rfc-should-we-omit-local-symbols-in-eekciihgtfvflvnbieicunjlrtnufhuelf-files-from-the-lldb-symbol-table/87384 Improving symbolication by excluding local symbols that are typically not useful for debugging or symbol lookups. This aligns with the discussion that local symbols, especially those with STB_LOCAL binding and STT_NOTYPE type (including .L-prefixed symbols), often interfere with symbol resolution and can be safely omitted. --------- Co-authored-by: Bar Soloveychik <bars...@fb.com> Added: Modified: lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp lldb/unittests/ObjectFile/ELF/TestObjectFileELF.cpp Removed: ################################################################################ diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp index f69358de6a288..931baf5927a04 100644 --- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp +++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp @@ -2037,6 +2037,19 @@ static char FindArmAarch64MappingSymbol(const char *symbol_name) { return '\0'; } +static char FindRISCVMappingSymbol(const char *symbol_name) { + if (!symbol_name) + return '\0'; + + if (strcmp(symbol_name, "$d") == 0) { + return 'd'; + } + if (strcmp(symbol_name, "$x") == 0) { + return 'x'; + } + return '\0'; +} + #define STO_MIPS_ISA (3 << 6) #define STO_MICROMIPS (2 << 6) #define IS_MICROMIPS(ST_OTHER) (((ST_OTHER)&STO_MIPS_ISA) == STO_MICROMIPS) @@ -2102,6 +2115,12 @@ ObjectFileELF::ParseSymbols(Symtab *symtab, user_id_t start_id, if (!symbol_name) symbol_name = ""; + // Skip local symbols starting with ".L" because these are compiler + // generated local labels used for internal purposes (e.g. debugging, + // optimization) and are not relevant for symbol resolution or external + // linkage. + if (llvm::StringRef(symbol_name).starts_with(".L")) + continue; // No need to add non-section symbols that have no names if (symbol.getType() != STT_SECTION && (symbol_name == nullptr || symbol_name[0] == '\0')) @@ -2190,7 +2209,6 @@ ObjectFileELF::ParseSymbols(Symtab *symtab, user_id_t start_id, int64_t symbol_value_offset = 0; uint32_t additional_flags = 0; - if (arch.IsValid()) { if (arch.GetMachine() == llvm::Triple::arm) { if (symbol.getBinding() == STB_LOCAL) { @@ -2235,6 +2253,27 @@ ObjectFileELF::ParseSymbols(Symtab *symtab, user_id_t start_id, if (mapping_symbol) continue; } + } else if (arch.GetTriple().isRISCV()) { + if (symbol.getBinding() == STB_LOCAL) { + char mapping_symbol = FindRISCVMappingSymbol(symbol_name); + if (symbol_type == eSymbolTypeCode) { + // Only handle $d and $x mapping symbols. + // Other mapping symbols are ignored as they don't affect address + // classification. + switch (mapping_symbol) { + case 'x': + // $x - marks a RISCV instruction sequence + address_class_map[symbol.st_value] = AddressClass::eCode; + break; + case 'd': + // $d - marks a RISCV data item sequence + address_class_map[symbol.st_value] = AddressClass::eData; + break; + } + } + if (mapping_symbol) + continue; + } } if (arch.GetMachine() == llvm::Triple::arm) { diff --git a/lldb/unittests/ObjectFile/ELF/TestObjectFileELF.cpp b/lldb/unittests/ObjectFile/ELF/TestObjectFileELF.cpp index 80abc5b80f84d..411387832f733 100644 --- a/lldb/unittests/ObjectFile/ELF/TestObjectFileELF.cpp +++ b/lldb/unittests/ObjectFile/ELF/TestObjectFileELF.cpp @@ -308,3 +308,84 @@ TEST_F(ObjectFileELFTest, GetSymtab_NoSymEntryPointArmAddressClass) { auto entry_point_addr = module_sp->GetObjectFile()->GetEntryPointAddress(); ASSERT_EQ(entry_point_addr.GetAddressClass(), AddressClass::eCode); } + +TEST_F(ObjectFileELFTest, SkipsLocalMappingAndDotLSymbols) { + auto ExpectedFile = TestFile::fromYaml(R"( +--- !ELF + FileHeader: + Class: ELFCLASS64 + Data: ELFDATA2LSB + Type: ET_EXEC + Machine: EM_RISCV + Flags: [ EF_RISCV_RVC, EF_RISCV_FLOAT_ABI_SINGLE ] + Entry: 0xC0A1B010 + Sections: + - Name: .text + Type: SHT_PROGBITS + Flags: [ SHF_ALLOC, SHF_EXECINSTR ] + Address: 0x0000000000400180 + AddressAlign: 0x0000000000000010 + Content: 554889E5 + - Name: .data + Type: SHT_PROGBITS + Flags: [ SHF_WRITE, SHF_ALLOC ] + Address: 0x0000000000601000 + AddressAlign: 0x0000000000000004 + Content: 2F000000 + - Name: .riscv.attributes + Type: SHT_PROGBITS + Flags: [ SHF_ALLOC ] + Address: 0x0000000000610000 + AddressAlign: 0x0000000000000004 + Content: "00" + Symbols: + - Name: $d + Type: STT_NOTYPE + Section: .riscv.attributes + Value: 0x0000000000400180 + Size: 0x10 + Binding: STB_LOCAL + - Name: $x + Type: STT_NOTYPE + Section: .text + Value: 0xC0A1B010 + Size: 0x10 + Binding: STB_LOCAL + - Name: .Lfoo + Type: STT_OBJECT + Section: .data + Value: 0x0000000000601000 + Size: 0x4 + Binding: STB_LOCAL + - Name: global_func + Type: STT_FUNC + Section: .text + Value: 0x00000000004001A0 + Size: 0x10 + Binding: STB_GLOBAL + - Name: global_obj + Type: STT_OBJECT + Section: .data + Value: 0x0000000000601004 + Size: 0x4 + Binding: STB_GLOBAL +... + )"); + ASSERT_THAT_EXPECTED(ExpectedFile, llvm::Succeeded()); + auto module_sp = std::make_shared<Module>(ExpectedFile->moduleSpec()); + auto *symtab = module_sp->GetSymtab(); + ASSERT_NE(nullptr, symtab); + EXPECT_EQ(nullptr, module_sp->FindFirstSymbolWithNameAndType( + ConstString("$d"), eSymbolTypeAny)); + EXPECT_EQ(nullptr, module_sp->FindFirstSymbolWithNameAndType( + ConstString("$x"), eSymbolTypeAny)); + EXPECT_EQ(nullptr, module_sp->FindFirstSymbolWithNameAndType( + ConstString(".Lfoo"), eSymbolTypeAny)); + // assert that other symbols are present + const Symbol *global_func = module_sp->FindFirstSymbolWithNameAndType( + ConstString("global_func"), eSymbolTypeAny); + ASSERT_NE(nullptr, global_func); + const Symbol *global_obj = module_sp->FindFirstSymbolWithNameAndType( + ConstString("global_obj"), eSymbolTypeAny); + ASSERT_NE(nullptr, global_obj); +} _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
