//===- MCDwarf.h - Machine Code Dwarf support -------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains the declaration of the MCDwarfFile to support the dwarf
// .file directive and the .loc directive.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCDWARF_H
#define LLVM_MC_MCDWARF_H
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/MD5.h"
#include "llvm/Support/StringSaver.h"
#include <cassert>
#include <cstdint>
#include <optional>
#include <string>
#include <utility>
#include <vector>
namespace llvm {
template <typename T> class ArrayRef;
class MCAsmBackend;
class MCContext;
class MCObjectStreamer;
class MCSection;
class MCStreamer;
class MCSymbol;
class raw_ostream;
class SMLoc;
class SourceMgr;
namespace mcdwarf {
// Emit the common part of the DWARF 5 range/locations list tables header.
MCSymbol *emitListsTableHeaderStart(MCStreamer &S);
} // namespace mcdwarf
/// Manage the .debug_line_str section contents, if we use it.
class MCDwarfLineStr {
BumpPtrAllocator Alloc;
StringSaver Saver{Alloc};
MCSymbol *LineStrLabel = nullptr;
StringTableBuilder LineStrings{StringTableBuilder::DWARF};
bool UseRelocs = false;
public:
/// Construct an instance that can emit .debug_line_str (for use in a normal
/// v5 line table).
explicit MCDwarfLineStr(MCContext &Ctx);
StringSaver &getSaver() { return Saver; }
/// Emit a reference to the string.
void emitRef(MCStreamer *MCOS, StringRef Path);
/// Emit the .debug_line_str section if appropriate.
void emitSection(MCStreamer *MCOS);
/// Returns finalized section.
SmallString<0> getFinalizedData();
};
/// Instances of this class represent the name of the dwarf .file directive and
/// its associated dwarf file number in the MC file. MCDwarfFile's are created
/// and uniqued by the MCContext class. In Dwarf 4 file numbers start from 1;
/// i.e. the entry with file number 1 is the first element in the vector of
/// DwarfFiles and there is no MCDwarfFile with file number 0. In Dwarf 5 file
/// numbers start from 0, with the MCDwarfFile with file number 0 being the
/// primary source file, and file numbers correspond to their index in the
/// vector.
struct MCDwarfFile {
// The base name of the file without its directory path.
std::string Name;
// The index into the list of directory names for this file name.
unsigned DirIndex = 0;
/// The MD5 checksum, if there is one. Non-owning pointer to data allocated
/// in MCContext.
std::optional<MD5::MD5Result> Checksum;
/// The source code of the file. Non-owning reference to data allocated in
/// MCContext.
std::optional<StringRef> Source;
};
/// Instances of this class represent the information from a
/// dwarf .loc directive.
class MCDwarfLoc {
uint32_t FileNum;
uint32_t Line;
uint16_t Column;
// Flags (see #define's below)
uint8_t Flags;
uint8_t Isa;
uint32_t Discriminator;
// Flag that indicates the initial value of the is_stmt_start flag.
#define DWARF2_LINE_DEFAULT_IS_STMT 1
#define DWARF2_FLAG_IS_STMT (1 << 0)
#define DWARF2_FLAG_BASIC_BLOCK (1 << 1)
#define DWARF2_FLAG_PROLOGUE_END (1 << 2)
#define DWARF2_FLAG_EPILOGUE_BEGIN (1 << 3)
private: // MCContext manages these
friend class MCContext;
friend class MCDwarfLineEntry;
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.
public:
/// Get the FileNum of this MCDwarfLoc.
unsigned getFileNum() const { return FileNum; }
/// Get the Line of this MCDwarfLoc.
unsigned getLine() const { return Line; }
/// Get the Column of this MCDwarfLoc.
unsigned getColumn() const { return Column; }
/// Get the Flags of this MCDwarfLoc.
unsigned getFlags() const { return Flags; }
/// Get the Isa of this MCDwarfLoc.
unsigned getIsa() const { return Isa; }
/// Get the Discriminator of this MCDwarfLoc.
unsigned getDiscriminator() const { return Discriminator; }
/// Set the FileNum of this MCDwarfLoc.
void setFileNum(unsigned fileNum) { FileNum = fileNum; }
/// Set the Line of this MCDwarfLoc.
void setLine(unsigned line) { Line = line; }
/// Set the Column of this MCDwarfLoc.
void setColumn(unsigned column) {
assert(column <= UINT16_MAX);
Column = column;
}
/// Set the Flags of this MCDwarfLoc.
void setFlags(unsigned flags) {
assert(flags <= UINT8_MAX);
Flags = flags;
}
/// Set the Isa of this MCDwarfLoc.
void setIsa(unsigned isa) {
assert(isa <= UINT8_MAX);
Isa = isa;
}
/// Set the Discriminator of this MCDwarfLoc.
void setDiscriminator(unsigned discriminator) {
Discriminator = discriminator;
}
};
/// 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 MCDwarfLineEntry : public MCDwarfLoc {
MCSymbol *Label;
private:
// Allow the default copy constructor and assignment operator to be used
// for an MCDwarfLineEntry object.
public:
// Constructor to create an MCDwarfLineEntry given a symbol and the dwarf loc.
MCDwarfLineEntry(MCSymbol *label, const MCDwarfLoc loc)
: MCDwarfLoc(loc), Label(label) {}
MCSymbol *getLabel() const { return Label; }
// This indicates the line entry is synthesized for an end entry.
bool IsEndEntry = false;
// Override the label with the given EndLabel.
void setEndLabel(MCSymbol *EndLabel) {
Label = EndLabel;
IsEndEntry = true;
}
// 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(MCStreamer *MCOS, MCSection *Section);
};
/// 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 {
public:
// Add an entry to this MCLineSection's line entries.
void addLineEntry(const MCDwarfLineEntry &LineEntry, MCSection *Sec) {
MCLineDivisions[Sec].push_back(LineEntry);
}
// Add an end entry by cloning the last entry, if exists, for the section
// the given EndLabel belongs to. The label is replaced by the given EndLabel.
void addEndEntry(MCSymbol *EndLabel);
using MCDwarfLineEntryCollection = std::vector<MCDwarfLineEntry>;
using iterator = MCDwarfLineEntryCollection::iterator;
using const_iterator = MCDwarfLineEntryCollection::const_iterator;
using MCLineDivisionMap = MapVector<MCSection *, MCDwarfLineEntryCollection>;
private:
// A collection of MCDwarfLineEntry for each section.
MCLineDivisionMap MCLineDivisions;
public:
// Returns the collection of MCDwarfLineEntry for a given Compile Unit ID.
const MCLineDivisionMap &getMCLineEntries() const {
return MCLineDivisions;
}
};
struct MCDwarfLineTableParams {
/// First special line opcode - leave room for the standard opcodes.
/// Note: If you want to change this, you'll have to update the
/// "StandardOpcodeLengths" table that is emitted in
/// \c Emit().
uint8_t DWARF2LineOpcodeBase = 13;
/// Minimum line offset in a special line info. opcode. The value
/// -5 was chosen to give a reasonable range of values.
int8_t DWARF2LineBase = -5;
/// Range of line offsets in a special line info. opcode.
uint8_t DWARF2LineRange = 14;
};
struct MCDwarfLineTableHeader {
MCSymbol *Label = nullptr;
SmallVector<std::string, 3> MCDwarfDirs;
SmallVector<MCDwarfFile, 3> MCDwarfFiles;
StringMap<unsigned> SourceIdMap;
std::string CompilationDir;
MCDwarfFile RootFile;
bool HasSource = false;
private:
bool HasAllMD5 = true;
bool HasAnyMD5 = false;
public:
MCDwarfLineTableHeader() = default;
Expected<unsigned> tryGetFile(StringRef &Directory, StringRef &FileName,
std::optional<MD5::MD5Result> Checksum,
std::optional<StringRef> Source,
uint16_t DwarfVersion, unsigned FileNumber = 0);
std::pair<MCSymbol *, MCSymbol *>
Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
std::optional<MCDwarfLineStr> &LineStr) const;
std::pair<MCSymbol *, MCSymbol *>
Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
ArrayRef<char> SpecialOpcodeLengths,
std::optional<MCDwarfLineStr> &LineStr) const;
void resetMD5Usage() {
HasAllMD5 = true;
HasAnyMD5 = false;
}
void trackMD5Usage(bool MD5Used) {
HasAllMD5 &= MD5Used;
HasAnyMD5 |= MD5Used;
}
bool isMD5UsageConsistent() const {
return MCDwarfFiles.empty() || (HasAllMD5 == HasAnyMD5);
}
void setRootFile(StringRef Directory, StringRef FileName,
std::optional<MD5::MD5Result> Checksum,
std::optional<StringRef> Source) {
CompilationDir = std::string(Directory);
RootFile.Name = std::string(FileName);
RootFile.DirIndex = 0;
RootFile.Checksum = Checksum;
RootFile.Source = Source;
trackMD5Usage(Checksum.has_value());
HasSource = Source.has_value();
}
void resetFileTable() {
MCDwarfDirs.clear();
MCDwarfFiles.clear();
RootFile.Name.clear();
resetMD5Usage();
HasSource = false;
}
private:
void emitV2FileDirTables(MCStreamer *MCOS) const;
void emitV5FileDirTables(MCStreamer *MCOS,
std::optional<MCDwarfLineStr> &LineStr) const;
};
class MCDwarfDwoLineTable {
MCDwarfLineTableHeader Header;
bool HasSplitLineTable = false;
public:
void maybeSetRootFile(StringRef Directory, StringRef FileName,
std::optional<MD5::MD5Result> Checksum,
std::optional<StringRef> Source) {
if (!Header.RootFile.Name.empty())
return;
Header.setRootFile(Directory, FileName, Checksum, Source);
}
unsigned getFile(StringRef Directory, StringRef FileName,
std::optional<MD5::MD5Result> Checksum,
uint16_t DwarfVersion, std::optional<StringRef> Source) {
HasSplitLineTable = true;
return cantFail(Header.tryGetFile(Directory, FileName, Checksum, Source,
DwarfVersion));
}
void Emit(MCStreamer &MCOS, MCDwarfLineTableParams Params,
MCSection *Section) const;
};
class MCDwarfLineTable {
MCDwarfLineTableHeader Header;
MCLineSection MCLineSections;
public:
// This emits the Dwarf file and the line tables for all Compile Units.
static void emit(MCStreamer *MCOS, MCDwarfLineTableParams Params);
// This emits the Dwarf file and the line tables for a given Compile Unit.
void emitCU(MCStreamer *MCOS, MCDwarfLineTableParams Params,
std::optional<MCDwarfLineStr> &LineStr) const;
// This emits a single line table associated with a given Section.
static void
emitOne(MCStreamer *MCOS, MCSection *Section,
const MCLineSection::MCDwarfLineEntryCollection &LineEntries);
Expected<unsigned> tryGetFile(StringRef &Directory, StringRef &FileName,
std::optional<MD5::MD5Result> Checksum,
std::optional<StringRef> Source,
uint16_t DwarfVersion, unsigned FileNumber = 0);
unsigned getFile(StringRef &Directory, StringRef &FileName,
std::optional<MD5::MD5Result> Checksum,
std::optional<StringRef> Source, uint16_t DwarfVersion,
unsigned FileNumber = 0) {
return cantFail(tryGetFile(Directory, FileName, Checksum, Source,
DwarfVersion, FileNumber));
}
void setRootFile(StringRef Directory, StringRef FileName,
std::optional<MD5::MD5Result> Checksum,
std::optional<StringRef> Source) {
Header.CompilationDir = std::string(Directory);
Header.RootFile.Name = std::string(FileName);
Header.RootFile.DirIndex = 0;
Header.RootFile.Checksum = Checksum;
Header.RootFile.Source = Source;
Header.trackMD5Usage(Checksum.has_value());
Header.HasSource = Source.has_value();
}
void resetFileTable() { Header.resetFileTable(); }
bool hasRootFile() const { return !Header.RootFile.Name.empty(); }
MCDwarfFile &getRootFile() { return Header.RootFile; }
const MCDwarfFile &getRootFile() const { return Header.RootFile; }
// Report whether MD5 usage has been consistent (all-or-none).
bool isMD5UsageConsistent() const { return Header.isMD5UsageConsistent(); }
MCSymbol *getLabel() const {
return Header.Label;
}
void setLabel(MCSymbol *Label) {
Header.Label = Label;
}
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 {
public:
/// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
static void Encode(MCContext &Context, MCDwarfLineTableParams Params,
int64_t LineDelta, uint64_t AddrDelta, raw_ostream &OS);
/// Utility function to emit the encoding to a streamer.
static void Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
int64_t LineDelta, uint64_t AddrDelta);
};
class MCGenDwarfInfo {
public:
//
// 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 {
private:
// 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;
public:
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 {
public:
enum OpType {
OpSameValue,
OpRememberState,
OpRestoreState,
OpOffset,
OpLLVMDefAspaceCfa,
OpDefCfaRegister,
OpDefCfaOffset,
OpDefCfa,
OpRelOffset,
OpAdjustCfaOffset,
OpEscape,
OpRestore,
OpUndefined,
OpRegister,
OpWindowSave,
OpNegateRAState,
OpGnuArgsSize
};
private:
OpType Operation;
MCSymbol *Label;
unsigned Register;
union {
int Offset;
unsigned Register2;
};
unsigned AddressSpace;
std::vector<char> Values;
std::string Comment;
MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R, int O, StringRef V,
StringRef Comment = "")
: Operation(Op), Label(L), Register(R), Offset(O),
Values(V.begin(), V.end()), Comment(Comment) {
assert(Op != OpRegister && Op != OpLLVMDefAspaceCfa);
}
MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R1, unsigned R2)
: Operation(Op), Label(L), Register(R1), Register2(R2) {
assert(Op == OpRegister);
}
MCCFIInstruction(OpType Op, MCSymbol *L, unsigned R, int O, unsigned AS)
: Operation(Op), Label(L), Register(R), Offset(O), AddressSpace(AS) {
assert(Op == OpLLVMDefAspaceCfa);
}
public:
/// .cfi_def_cfa defines a rule for computing CFA as: take address from
/// Register and add Offset to it.
static MCCFIInstruction cfiDefCfa(MCSymbol *L, unsigned Register,
int Offset) {
return MCCFIInstruction(OpDefCfa, L, Register, Offset, "");
}
/// .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, "");
}
/// .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 cfiDefCfaOffset(MCSymbol *L, int Offset) {
return MCCFIInstruction(OpDefCfaOffset, L, 0, Offset, "");
}
/// .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, "");
}
// FIXME: Update the remaining docs to use the new proposal wording.
/// .cfi_llvm_def_aspace_cfa defines the rule for computing the CFA to
/// be the result of evaluating the DWARF operation expression
/// `DW_OP_constu AS; DW_OP_aspace_bregx R, B` as a location description.
static MCCFIInstruction createLLVMDefAspaceCfa(MCSymbol *L, unsigned Register,
int Offset,
unsigned AddressSpace) {
return MCCFIInstruction(OpLLVMDefAspaceCfa, L, Register, Offset,
AddressSpace);
}
/// .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, "");
}
/// .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, "");
}
/// .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);
}
/// .cfi_window_save SPARC register window is saved.
static MCCFIInstruction createWindowSave(MCSymbol *L) {
return MCCFIInstruction(OpWindowSave, L, 0, 0, "");
}
/// .cfi_negate_ra_state AArch64 negate RA state.
static MCCFIInstruction createNegateRAState(MCSymbol *L) {
return MCCFIInstruction(OpNegateRAState, L, 0, 0, "");
}
/// .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, "");
}
/// .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, "");
}
/// .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, "");
}
/// .cfi_remember_state Save all current rules for all registers.
static MCCFIInstruction createRememberState(MCSymbol *L) {
return MCCFIInstruction(OpRememberState, L, 0, 0, "");
}
/// .cfi_restore_state Restore the previously saved state.
static MCCFIInstruction createRestoreState(MCSymbol *L) {
return MCCFIInstruction(OpRestoreState, L, 0, 0, "");
}
/// .cfi_escape Allows the user to add arbitrary bytes to the unwind
/// info.
static MCCFIInstruction createEscape(MCSymbol *L, StringRef Vals,
StringRef Comment = "") {
return MCCFIInstruction(OpEscape, L, 0, 0, Vals, Comment);
}
/// A special wrapper for .cfi_escape that indicates GNU_ARGS_SIZE
static MCCFIInstruction createGnuArgsSize(MCSymbol *L, int Size) {
return MCCFIInstruction(OpGnuArgsSize, L, 0, Size, "");
}
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 ||
Operation == OpLLVMDefAspaceCfa);
return Register;
}
unsigned getRegister2() const {
assert(Operation == OpRegister);
return Register2;
}
unsigned getAddressSpace() const {
assert(Operation == OpLLVMDefAspaceCfa);
return AddressSpace;
}
int getOffset() const {
assert(Operation == OpDefCfa || Operation == OpOffset ||
Operation == OpRelOffset || Operation == OpDefCfaOffset ||
Operation == OpAdjustCfaOffset || Operation == OpGnuArgsSize ||
Operation == OpLLVMDefAspaceCfa);
return Offset;
}
StringRef getValues() const {
assert(Operation == OpEscape);
return StringRef(&Values[0], Values.size());
}
StringRef getComment() const {
return Comment;
}
};
struct MCDwarfFrameInfo {
MCDwarfFrameInfo() = default;
MCSymbol *Begin = nullptr;
MCSymbol *End = nullptr;
const MCSymbol *Personality = nullptr;
const MCSymbol *Lsda = nullptr;
std::vector<MCCFIInstruction> Instructions;
unsigned CurrentCfaRegister = 0;
unsigned PersonalityEncoding = 0;
unsigned LsdaEncoding = 0;
uint32_t CompactUnwindEncoding = 0;
bool IsSignalFrame = false;
bool IsSimple = false;
unsigned RAReg = static_cast<unsigned>(INT_MAX);
bool IsBKeyFrame = false;
bool IsMTETaggedFrame = false;
};
class MCDwarfFrameEmitter {
public:
//
// 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
#endif // LLVM_MC_MCDWARF_H