diff options
Diffstat (limited to 'lib/MC/MCDwarf.cpp')
| -rw-r--r-- | lib/MC/MCDwarf.cpp | 339 |
1 files changed, 339 insertions, 0 deletions
diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp index 8157b4177a..46ab65ffeb 100644 --- a/lib/MC/MCDwarf.cpp +++ b/lib/MC/MCDwarf.cpp @@ -19,9 +19,12 @@ #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/raw_ostream.h" +#include "llvm/Support/Path.h" +#include "llvm/Support/SourceMgr.h" #include "llvm/ADT/FoldingSet.h" #include "llvm/ADT/SmallString.h" #include "llvm/ADT/Twine.h" +#include "llvm/Config/config.h" using namespace llvm; // Given a special op, return the address skip amount (in units of @@ -423,6 +426,342 @@ void MCDwarfFile::dump() const { print(dbgs()); } +// Utility function to write a tuple for .debug_abbrev. +static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) { + MCOS->EmitULEB128IntValue(Name); + MCOS->EmitULEB128IntValue(Form); +} + +// When generating dwarf for assembly source files this emits +// the data for .debug_abbrev section which contains three DIEs. +static void EmitGenDwarfAbbrev(MCStreamer *MCOS) { + MCContext &context = MCOS->getContext(); + MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection()); + + // DW_TAG_compile_unit DIE abbrev (1). + MCOS->EmitULEB128IntValue(1); + MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit); + MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1); + EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4); + EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr); + EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr); + EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string); + EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string); + StringRef DwarfDebugFlags = context.getDwarfDebugFlags(); + if (!DwarfDebugFlags.empty()) + EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string); + EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string); + EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2); + EmitAbbrev(MCOS, 0, 0); + + // DW_TAG_subprogram DIE abbrev (2). + MCOS->EmitULEB128IntValue(2); + MCOS->EmitULEB128IntValue(dwarf::DW_TAG_subprogram); + MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1); + EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string); + EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4); + EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4); + EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr); + EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr); + EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag); + EmitAbbrev(MCOS, 0, 0); + + // DW_TAG_unspecified_parameters DIE abbrev (3). + MCOS->EmitULEB128IntValue(3); + MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters); + MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1); + EmitAbbrev(MCOS, 0, 0); + + // Terminate the abbreviations for this compilation unit. + MCOS->EmitIntValue(0, 1); +} + +// When generating dwarf for assembly source files this emits the data for +// .debug_aranges section. Which contains a header and a table of pairs of +// PointerSize'ed values for the address and size of section(s) with line table +// entries (just the default .text in our case) and a terminating pair of zeros. +static void EmitGenDwarfAranges(MCStreamer *MCOS) { + MCContext &context = MCOS->getContext(); + + // Create a symbol at the end of the section that we are creating the dwarf + // debugging info to use later in here as part of the expression to calculate + // the size of the section for the table. + MCOS->SwitchSection(context.getGenDwarfSection()); + MCSymbol *SectionEndSym = context.CreateTempSymbol(); + MCOS->EmitLabel(SectionEndSym); + context.setGenDwarfSectionEndSym(SectionEndSym); + + MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection()); + + // This will be the length of the .debug_aranges section, first account for + // the size of each item in the header (see below where we emit these items). + int Length = 4 + 2 + 4 + 1 + 1; + + // Figure the padding after the header before the table of address and size + // pairs who's values are PointerSize'ed. + const MCAsmInfo &asmInfo = context.getAsmInfo(); + int AddrSize = asmInfo.getPointerSize(); + int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1)); + if (Pad == 2 * AddrSize) + Pad = 0; + Length += Pad; + + // Add the size of the pair of PointerSize'ed values for the address and size + // of the one default .text section we have in the table. + Length += 2 * AddrSize; + // And the pair of terminating zeros. + Length += 2 * AddrSize; + + + // Emit the header for this section. + // The 4 byte length not including the 4 byte value for the length. + MCOS->EmitIntValue(Length - 4, 4); + // The 2 byte version, which is 2. + MCOS->EmitIntValue(2, 2); + // The 4 byte offset to the compile unit in the .debug_info from the start + // of the .debug_info, it is at the start of that section so this is zero. + MCOS->EmitIntValue(0, 4); + // The 1 byte size of an address. + MCOS->EmitIntValue(AddrSize, 1); + // The 1 byte size of a segment descriptor, we use a value of zero. + MCOS->EmitIntValue(0, 1); + // Align the header with the padding if needed, before we put out the table. + for(int i = 0; i < Pad; i++) + MCOS->EmitIntValue(0, 1); + + // Now emit the table of pairs of PointerSize'ed values for the section(s) + // address and size, in our case just the one default .text section. + const MCExpr *Addr = MCSymbolRefExpr::Create( + context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context); + const MCExpr *Size = MakeStartMinusEndExpr(*MCOS, + *context.getGenDwarfSectionStartSym(), *SectionEndSym, 0); + MCOS->EmitAbsValue(Addr, AddrSize); + MCOS->EmitAbsValue(Size, AddrSize); + + // And finally the pair of terminating zeros. + MCOS->EmitIntValue(0, AddrSize); + MCOS->EmitIntValue(0, AddrSize); +} + +// When generating dwarf for assembly source files this emits the data for +// .debug_info section which contains three parts. The header, the compile_unit +// DIE and a list of subprogram DIEs. +static void EmitGenDwarfInfo(MCStreamer *MCOS) { + MCContext &context = MCOS->getContext(); + + MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection()); + + // Create a symbol at the start and end of this section used in here for the + // expression to calculate the length in the header. + MCSymbol *InfoStart = context.CreateTempSymbol(); + MCOS->EmitLabel(InfoStart); + MCSymbol *InfoEnd = context.CreateTempSymbol(); + + // First part: the header. + + // The 4 byte total length of the information for this compilation unit, not + // including these 4 bytes. + const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4); + MCOS->EmitAbsValue(Length, 4); + + // The 2 byte DWARF version, which is 2. + MCOS->EmitIntValue(2, 2); + + // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev, + // it is at the start of that section so this is zero. + MCOS->EmitIntValue(0, 4); + + const MCAsmInfo &asmInfo = context.getAsmInfo(); + int AddrSize = asmInfo.getPointerSize(); + // The 1 byte size of an address. + MCOS->EmitIntValue(AddrSize, 1); + + // Second part: the compile_unit DIE. + + // The DW_TAG_compile_unit DIE abbrev (1). + MCOS->EmitULEB128IntValue(1); + + // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section, + // which is at the start of that section so this is zero. + MCOS->EmitIntValue(0, 4); + + // AT_low_pc, the first address of the default .text section. + const MCExpr *Start = MCSymbolRefExpr::Create( + context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context); + MCOS->EmitAbsValue(Start, AddrSize); + + // AT_high_pc, the last address of the default .text section. + const MCExpr *End = MCSymbolRefExpr::Create( + context.getGenDwarfSectionEndSym(), MCSymbolRefExpr::VK_None, context); + MCOS->EmitAbsValue(End, AddrSize); + + // AT_name, the name of the source file. Reconstruct from the first directory + // and file table entries. + const std::vector<StringRef> &MCDwarfDirs = + context.getMCDwarfDirs(); + if (MCDwarfDirs.size() > 0) { + MCOS->EmitBytes(MCDwarfDirs[0], 0); + MCOS->EmitBytes("/", 0); + } + const std::vector<MCDwarfFile *> &MCDwarfFiles = + MCOS->getContext().getMCDwarfFiles(); + MCOS->EmitBytes(MCDwarfFiles[1]->getName(), 0); + MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. + + // AT_comp_dir, the working directory the assembly was done in. + llvm::sys::Path CWD = llvm::sys::Path::GetCurrentDirectory(); + MCOS->EmitBytes(StringRef(CWD.c_str()), 0); + MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. + + // AT_APPLE_flags, the command line arguments of the assembler tool. + StringRef DwarfDebugFlags = context.getDwarfDebugFlags(); + if (!DwarfDebugFlags.empty()){ + MCOS->EmitBytes(DwarfDebugFlags, 0); + MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. + } + + // AT_producer, the version of the assembler tool. + MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM "), 0); + MCOS->EmitBytes(StringRef(PACKAGE_VERSION), 0); + MCOS->EmitBytes(StringRef(")"), 0); + MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. + + // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2 + // draft has no standard code for assembler. + MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2); + + // Third part: the list of subprogram DIEs. + + // Loop on saved info for dwarf subprograms and create the DIEs for them. + const std::vector<const MCGenDwarfSubprogramEntry *> &Entries = + MCOS->getContext().getMCGenDwarfSubprogramEntries(); + for (std::vector<const MCGenDwarfSubprogramEntry *>::const_iterator it = + Entries.begin(), ie = Entries.end(); it != ie; + ++it) { + const MCGenDwarfSubprogramEntry *Entry = *it; + + // The DW_TAG_subprogram DIE abbrev (2). + MCOS->EmitULEB128IntValue(2); + + // AT_name, of the label without any leading underbar. + MCOS->EmitBytes(Entry->getName(), 0); + MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. + + // AT_decl_file, index into the file table. + MCOS->EmitIntValue(Entry->getFileNumber(), 4); + + // AT_decl_line, source line number. + MCOS->EmitIntValue(Entry->getLineNumber(), 4); + + // AT_low_pc, start address of the label. + const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry->getLabel(), + MCSymbolRefExpr::VK_None, context); + MCOS->EmitAbsValue(AT_low_pc, AddrSize); + + // AT_high_pc, end address which is the next label or end of the section. + std::vector<const MCGenDwarfSubprogramEntry *>::const_iterator next = it+1; + if (next != Entries.end()){ + const MCGenDwarfSubprogramEntry *NextEntry = *next; + const MCExpr *AT_high_pc = MCSymbolRefExpr::Create(NextEntry->getLabel(), + MCSymbolRefExpr::VK_None, context); + MCOS->EmitAbsValue(AT_high_pc, AddrSize); + } else { + MCOS->EmitAbsValue(End, AddrSize); + } + + // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype. + MCOS->EmitIntValue(0, 1); + + // The DW_TAG_unspecified_parameters DIE abbrev (3). + MCOS->EmitULEB128IntValue(3); + + // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's. + MCOS->EmitIntValue(0, 1); + } + // Deallocate the MCGenDwarfSubprogramEntry classes that saved away the info + // for the dwarf subprograms. + for (std::vector<const MCGenDwarfSubprogramEntry *>::const_iterator it = + Entries.begin(), ie = Entries.end(); it != ie; + ++it) { + const MCGenDwarfSubprogramEntry *Entry = *it; + delete Entry; + } + + // Add the NULL DIE terminating the Compile Unit DIE's. + MCOS->EmitIntValue(0, 1); + + // Now set the value of the symbol at the end of the info section. + MCOS->EmitLabel(InfoEnd); +} + +// +// When generating dwarf for assembly source files this emits the Dwarf +// sections. +// +void MCGenDwarfInfo::Emit(MCStreamer *MCOS) { + // Create the dwarf sections in this order (.debug_line already created). + MCContext &context = MCOS->getContext(); + MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection()); + MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection()); + MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection()); + + // If there are no line table entries then do not emit any section contents. + if (context.getMCLineSections().empty()) + return; + + // Output the data for .debug_aranges section. + EmitGenDwarfAranges(MCOS); + + // Output the data for .debug_abbrev section. + EmitGenDwarfAbbrev(MCOS); + + // Output the data for .debug_info section. + EmitGenDwarfInfo(MCOS); +} + +// +// When generating dwarf for assembly source files this is called when symbol +// for a label is created. If this symbol is not a temporary and is in the +// section that dwarf is being generated for, save the needed info to create +// a dwarf subprogram. +// +void MCGenDwarfSubprogramEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS, + SourceMgr &SrcMgr, SMLoc &Loc) { + // We won't create dwarf subprogram's for temporary symbols or symbols not in + // the default text. + if (Symbol->isTemporary()) + return; + MCContext &context = MCOS->getContext(); + if (context.getGenDwarfSection() != MCOS->getCurrentSection()) + return; + + // The dwarf subprogram's name does not have the symbol name's leading + // underbar if any. + StringRef Name = Symbol->getName(); + if (Name.startswith("_")) + Name = Name.substr(1, Name.size()-1); + + // Get the dwarf file number to be used for the dwarf subprogram. + unsigned FileNumber = context.getGenDwarfFileNumber(); + + // Finding the line number is the expensive part which is why we just don't + // pass it in as for some symbols we won't create a dwarf subprogram. + int CurBuffer = SrcMgr.FindBufferContainingLoc(Loc); + unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer); + + // We create a temporary symbol for use for the AT_high_pc and AT_low_pc + // values so that they don't have things like an ARM thumb bit from the + // original symbol. So when used they won't get a low bit set after + // relocation. + MCSymbol *Label = context.CreateTempSymbol(); + MCOS->EmitLabel(Label); + + // Create and entry for the info and add it to the other entries. + MCGenDwarfSubprogramEntry *Entry = + new MCGenDwarfSubprogramEntry(Name, FileNumber, LineNumber, Label); + MCOS->getContext().addMCGenDwarfSubprogramEntry(Entry); +} + static int getDataAlignmentFactor(MCStreamer &streamer) { MCContext &context = streamer.getContext(); const MCAsmInfo &asmInfo = context.getAsmInfo(); |