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//===- MCDwarf.h - Machine Code Dwarf support -------------------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file contains the declaration of the MCDwarfFile to support the dwarf
// .file directive and the .loc directive.
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/raw_ostream.h"
#include <map>
#include <vector>
#include <string>
#include <utility>
namespace llvm {
class MCAsmBackend;
class MCContext;
class MCObjectStreamer;
class MCSection;
class MCStreamer;
class MCSymbol;
class SourceMgr;
class SMLoc;
/// MCDwarfFile - Instances of this class represent the name of the dwarf
/// .file directive and its associated dwarf file number in the MC file,
/// and MCDwarfFile's are created and unique'd by the MCContext class where
/// the file number for each is its index into the vector of DwarfFiles (note
/// index 0 is not used and not a valid dwarf file number).
struct MCDwarfFile {
// Name - the base name of the file without its directory path.
// The StringRef references memory allocated in the MCContext.
std::string Name;
// DirIndex - the index into the list of directory names for this file name.
unsigned DirIndex;
/// MCDwarfLoc - Instances of this class represent the information from a
/// dwarf .loc directive.
class MCDwarfLoc {
// FileNum - the file number.
unsigned FileNum;
// Line - the line number.
unsigned Line;
// Column - the column position.
unsigned Column;
// Flags (see #define's below)
unsigned Flags;
// Isa
unsigned Isa;
// Discriminator
unsigned Discriminator;
// Flag that indicates the initial value of the is_stmt_start flag.
#define DWARF2_FLAG_IS_STMT (1 << 0)
#define DWARF2_FLAG_BASIC_BLOCK (1 << 1)
#define DWARF2_FLAG_PROLOGUE_END (1 << 2)
private: // MCContext manages these
friend class MCContext;
friend class MCLineEntry;
MCDwarfLoc(unsigned fileNum, unsigned line, unsigned column, unsigned flags,
unsigned isa, unsigned discriminator)
: FileNum(fileNum), Line(line), Column(column), Flags(flags), Isa(isa),
Discriminator(discriminator) {}
// Allow the default copy constructor and assignment operator to be used
// for an MCDwarfLoc object.
/// getFileNum - Get the FileNum of this MCDwarfLoc.
unsigned getFileNum() const { return FileNum; }
/// getLine - Get the Line of this MCDwarfLoc.
unsigned getLine() const { return Line; }
/// getColumn - Get the Column of this MCDwarfLoc.
unsigned getColumn() const { return Column; }
/// getFlags - Get the Flags of this MCDwarfLoc.
unsigned getFlags() const { return Flags; }
/// getIsa - Get the Isa of this MCDwarfLoc.
unsigned getIsa() const { return Isa; }
/// getDiscriminator - Get the Discriminator of this MCDwarfLoc.
unsigned getDiscriminator() const { return Discriminator; }
/// setFileNum - Set the FileNum of this MCDwarfLoc.
void setFileNum(unsigned fileNum) { FileNum = fileNum; }
/// setLine - Set the Line of this MCDwarfLoc.
void setLine(unsigned line) { Line = line; }
/// setColumn - Set the Column of this MCDwarfLoc.
void setColumn(unsigned column) { Column = column; }
/// setFlags - Set the Flags of this MCDwarfLoc.
void setFlags(unsigned flags) { Flags = flags; }
/// setIsa - Set the Isa of this MCDwarfLoc.
void setIsa(unsigned isa) { Isa = isa; }
/// setDiscriminator - Set the Discriminator of this MCDwarfLoc.
void setDiscriminator(unsigned discriminator) {
Discriminator = discriminator;
/// MCLineEntry - Instances of this class represent the line information for
/// the dwarf line table entries. Which is created after a machine
/// instruction is assembled and uses an address from a temporary label
/// created at the current address in the current section and the info from
/// the last .loc directive seen as stored in the context.
class MCLineEntry : public MCDwarfLoc {
MCSymbol *Label;
// Allow the default copy constructor and assignment operator to be used
// for an MCLineEntry object.
// Constructor to create an MCLineEntry given a symbol and the dwarf loc.
MCLineEntry(MCSymbol *label, const MCDwarfLoc loc)
: MCDwarfLoc(loc), Label(label) {}
MCSymbol *getLabel() const { return Label; }
// This is called when an instruction is assembled into the specified
// section and if there is information from the last .loc directive that
// has yet to have a line entry made for it is made.
static void Make(MCObjectStreamer *MCOS, const MCSection *Section);
/// MCLineSection - Instances of this class represent the line information
/// for a compile unit where machine instructions have been assembled after seeing
/// .loc directives. This is the information used to build the dwarf line
/// table for a section.
class MCLineSection {
// addLineEntry - adds an entry to this MCLineSection's line entries
void addLineEntry(const MCLineEntry &LineEntry, const MCSection *Sec) {
typedef std::vector<MCLineEntry> MCLineEntryCollection;
typedef MCLineEntryCollection::iterator iterator;
typedef MCLineEntryCollection::const_iterator const_iterator;
typedef MapVector<const MCSection *, MCLineEntryCollection> MCLineDivisionMap;
// A collection of MCLineEntry for each section.
MCLineDivisionMap MCLineDivisions;
// Returns the collection of MCLineEntry for a given Compile Unit ID.
const MCLineDivisionMap &getMCLineEntries() const {
return MCLineDivisions;
struct MCDwarfLineTableHeader {
MCSymbol *Label;
SmallVector<std::string, 3> MCDwarfDirs;
SmallVector<MCDwarfFile, 3> MCDwarfFiles;
StringMap<unsigned> SourceIdMap;
StringRef CompilationDir;
MCDwarfLineTableHeader() : Label(nullptr) {}
unsigned getFile(StringRef &Directory, StringRef &FileName,
unsigned FileNumber = 0);
std::pair<MCSymbol *, MCSymbol *> Emit(MCStreamer *MCOS) const;
std::pair<MCSymbol *, MCSymbol *>
Emit(MCStreamer *MCOS, ArrayRef<char> SpecialOpcodeLengths) const;
class MCDwarfDwoLineTable {
MCDwarfLineTableHeader Header;
void setCompilationDir(StringRef CompilationDir) {
Header.CompilationDir = CompilationDir;
unsigned getFile(StringRef Directory, StringRef FileName) {
return Header.getFile(Directory, FileName);
void Emit(MCStreamer &MCOS) const;
class MCDwarfLineTable {
MCDwarfLineTableHeader Header;
MCLineSection MCLineSections;
// This emits the Dwarf file and the line tables for all Compile Units.
static void Emit(MCObjectStreamer *MCOS);
// This emits the Dwarf file and the line tables for a given Compile Unit.
void EmitCU(MCObjectStreamer *MCOS) const;
unsigned getFile(StringRef &Directory, StringRef &FileName,
unsigned FileNumber = 0);
MCSymbol *getLabel() const {
return Header.Label;
void setLabel(MCSymbol *Label) {
Header.Label = Label;
void setCompilationDir(StringRef CompilationDir) {
Header.CompilationDir = CompilationDir;
const SmallVectorImpl<std::string> &getMCDwarfDirs() const {
return Header.MCDwarfDirs;
SmallVectorImpl<std::string> &getMCDwarfDirs() {
return Header.MCDwarfDirs;
const SmallVectorImpl<MCDwarfFile> &getMCDwarfFiles() const {
return Header.MCDwarfFiles;
SmallVectorImpl<MCDwarfFile> &getMCDwarfFiles() {
return Header.MCDwarfFiles;
const MCLineSection &getMCLineSections() const {
return MCLineSections;
MCLineSection &getMCLineSections() {
return MCLineSections;
class MCDwarfLineAddr {
/// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
static void Encode(MCContext &Context, int64_t LineDelta, uint64_t AddrDelta,
raw_ostream &OS);
/// Utility function to emit the encoding to a streamer.
static void Emit(MCStreamer *MCOS, int64_t LineDelta, uint64_t AddrDelta);
class MCGenDwarfInfo {
// When generating dwarf for assembly source files this emits the Dwarf
// sections.
static void Emit(MCStreamer *MCOS);
// When generating dwarf for assembly source files this is the info that is
// needed to be gathered for each symbol that will have a dwarf label.
class MCGenDwarfLabelEntry {
// Name of the symbol without a leading underbar, if any.
StringRef Name;
// The dwarf file number this symbol is in.
unsigned FileNumber;
// The line number this symbol is at.
unsigned LineNumber;
// The low_pc for the dwarf label is taken from this symbol.
MCSymbol *Label;
MCGenDwarfLabelEntry(StringRef name, unsigned fileNumber, unsigned lineNumber,
MCSymbol *label)
: Name(name), FileNumber(fileNumber), LineNumber(lineNumber),
Label(label) {}
StringRef getName() const { return Name; }
unsigned getFileNumber() const { return FileNumber; }
unsigned getLineNumber() const { return LineNumber; }
MCSymbol *getLabel() const { return Label; }
// This is called when label is created when we are generating dwarf for
// assembly source files.
static void Make(MCSymbol *Symbol, MCStreamer *MCOS, SourceMgr &SrcMgr,
SMLoc &Loc);
class MCCFIInstruction {
enum OpType {
OpType Operation;
MCSymbol *Label;
unsigned Register;
union {
int Offset;
unsigned Register2;
std::vector<char> Values;
MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R, int O, StringRef V)
: Operation(Op), Label(L), Register(R), Offset(O),
Values(V.begin(), V.end()) {
assert(Op != OpRegister);
MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R1, unsigned R2)
: Operation(Op), Label(L), Register(R1), Register2(R2) {
assert(Op == OpRegister);
/// \brief .cfi_def_cfa defines a rule for computing CFA as: take address from
/// Register and add Offset to it.
static MCCFIInstruction createDefCfa(MCSymbol *L, unsigned Register,
int Offset) {
return MCCFIInstruction(OpDefCfa, L, Register, -Offset, "");
/// \brief .cfi_def_cfa_register modifies a rule for computing CFA. From now
/// on Register will be used instead of the old one. Offset remains the same.
static MCCFIInstruction createDefCfaRegister(MCSymbol *L, unsigned Register) {
return MCCFIInstruction(OpDefCfaRegister, L, Register, 0, "");
/// \brief .cfi_def_cfa_offset modifies a rule for computing CFA. Register
/// remains the same, but offset is new. Note that it is the absolute offset
/// that will be added to a defined register to the compute CFA address.
static MCCFIInstruction createDefCfaOffset(MCSymbol *L, int Offset) {
return MCCFIInstruction(OpDefCfaOffset, L, 0, -Offset, "");
/// \brief .cfi_adjust_cfa_offset Same as .cfi_def_cfa_offset, but
/// Offset is a relative value that is added/subtracted from the previous
/// offset.
static MCCFIInstruction createAdjustCfaOffset(MCSymbol *L, int Adjustment) {
return MCCFIInstruction(OpAdjustCfaOffset, L, 0, Adjustment, "");
/// \brief .cfi_offset Previous value of Register is saved at offset Offset
/// from CFA.
static MCCFIInstruction createOffset(MCSymbol *L, unsigned Register,
int Offset) {
return MCCFIInstruction(OpOffset, L, Register, Offset, "");
/// \brief .cfi_rel_offset Previous value of Register is saved at offset
/// Offset from the current CFA register. This is transformed to .cfi_offset
/// using the known displacement of the CFA register from the CFA.
static MCCFIInstruction createRelOffset(MCSymbol *L, unsigned Register,
int Offset) {
return MCCFIInstruction(OpRelOffset, L, Register, Offset, "");
/// \brief .cfi_register Previous value of Register1 is saved in
/// register Register2.
static MCCFIInstruction createRegister(MCSymbol *L, unsigned Register1,
unsigned Register2) {
return MCCFIInstruction(OpRegister, L, Register1, Register2);
/// \brief .cfi_window_save SPARC register window is saved.
static MCCFIInstruction createWindowSave(MCSymbol *L) {
return MCCFIInstruction(OpWindowSave, L, 0, 0, "");
/// \brief .cfi_restore says that the rule for Register is now the same as it
/// was at the beginning of the function, after all initial instructions added
/// by .cfi_startproc were executed.
static MCCFIInstruction createRestore(MCSymbol *L, unsigned Register) {
return MCCFIInstruction(OpRestore, L, Register, 0, "");
/// \brief .cfi_undefined From now on the previous value of Register can't be
/// restored anymore.
static MCCFIInstruction createUndefined(MCSymbol *L, unsigned Register) {
return MCCFIInstruction(OpUndefined, L, Register, 0, "");
/// \brief .cfi_same_value Current value of Register is the same as in the
/// previous frame. I.e., no restoration is needed.
static MCCFIInstruction createSameValue(MCSymbol *L, unsigned Register) {
return MCCFIInstruction(OpSameValue, L, Register, 0, "");
/// \brief .cfi_remember_state Save all current rules for all registers.
static MCCFIInstruction createRememberState(MCSymbol *L) {
return MCCFIInstruction(OpRememberState, L, 0, 0, "");
/// \brief .cfi_restore_state Restore the previously saved state.
static MCCFIInstruction createRestoreState(MCSymbol *L) {
return MCCFIInstruction(OpRestoreState, L, 0, 0, "");
/// \brief .cfi_escape Allows the user to add arbitrary bytes to the unwind
/// info.
static MCCFIInstruction createEscape(MCSymbol *L, StringRef Vals) {
return MCCFIInstruction(OpEscape, L, 0, 0, Vals);
OpType getOperation() const { return Operation; }
MCSymbol *getLabel() const { return Label; }
unsigned getRegister() const {
assert(Operation == OpDefCfa || Operation == OpOffset ||
Operation == OpRestore || Operation == OpUndefined ||
Operation == OpSameValue || Operation == OpDefCfaRegister ||
Operation == OpRelOffset || Operation == OpRegister);
return Register;
unsigned getRegister2() const {
assert(Operation == OpRegister);
return Register2;
int getOffset() const {
assert(Operation == OpDefCfa || Operation == OpOffset ||
Operation == OpRelOffset || Operation == OpDefCfaOffset ||
Operation == OpAdjustCfaOffset);
return Offset;
const StringRef getValues() const {
assert(Operation == OpEscape);
return StringRef(&Values[0], Values.size());
struct MCDwarfFrameInfo {
: Begin(nullptr), End(nullptr), Personality(nullptr), Lsda(nullptr),
Instructions(), PersonalityEncoding(), LsdaEncoding(0),
CompactUnwindEncoding(0), IsSignalFrame(false), IsSimple(false) {}
MCSymbol *Begin;
MCSymbol *End;
const MCSymbol *Personality;
const MCSymbol *Lsda;
std::vector<MCCFIInstruction> Instructions;
unsigned PersonalityEncoding;
unsigned LsdaEncoding;
uint32_t CompactUnwindEncoding;
bool IsSignalFrame;
bool IsSimple;
class MCDwarfFrameEmitter {
// This emits the frame info section.
static void Emit(MCObjectStreamer &streamer, MCAsmBackend *MAB, bool isEH);
static void EmitAdvanceLoc(MCObjectStreamer &Streamer, uint64_t AddrDelta);
static void EncodeAdvanceLoc(MCContext &Context, uint64_t AddrDelta,
raw_ostream &OS);
} // end namespace llvm