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llvm-mirror/lib/MC/MCDwarf.cpp
Esme-Yi 018bbe154e [Debug-Info] Add names for the debug line prologue. 
Summary: This is a minor patch to add names for the debug line prologue, as a follow-up of D95998.

Reviewed By: dblaikie, ikudrin, shchenz

Differential Revision: https://reviews.llvm.org/D98383
2021-03-12 04:45:08 +00:00

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//===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCDwarf.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/Config/config.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCObjectStreamer.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/EndianStream.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cstdint>
#include <string>
#include <utility>
#include <vector>
using namespace llvm;
MCSymbol *mcdwarf::emitListsTableHeaderStart(MCStreamer &S) {
MCSymbol *Start = S.getContext().createTempSymbol("debug_list_header_start");
MCSymbol *End = S.getContext().createTempSymbol("debug_list_header_end");
auto DwarfFormat = S.getContext().getDwarfFormat();
if (DwarfFormat == dwarf::DWARF64) {
S.AddComment("DWARF64 mark");
S.emitInt32(dwarf::DW_LENGTH_DWARF64);
}
S.AddComment("Length");
S.emitAbsoluteSymbolDiff(End, Start,
dwarf::getDwarfOffsetByteSize(DwarfFormat));
S.emitLabel(Start);
S.AddComment("Version");
S.emitInt16(S.getContext().getDwarfVersion());
S.AddComment("Address size");
S.emitInt8(S.getContext().getAsmInfo()->getCodePointerSize());
S.AddComment("Segment selector size");
S.emitInt8(0);
return End;
}
/// Manage the .debug_line_str section contents, if we use it.
class llvm::MCDwarfLineStr {
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) {
UseRelocs = Ctx.getAsmInfo()->doesDwarfUseRelocationsAcrossSections();
if (UseRelocs)
LineStrLabel =
Ctx.getObjectFileInfo()->getDwarfLineStrSection()->getBeginSymbol();
}
/// Emit a reference to the string.
void emitRef(MCStreamer *MCOS, StringRef Path);
/// Emit the .debug_line_str section if appropriate.
void emitSection(MCStreamer *MCOS);
};
static inline uint64_t ScaleAddrDelta(MCContext &Context, uint64_t AddrDelta) {
unsigned MinInsnLength = Context.getAsmInfo()->getMinInstAlignment();
if (MinInsnLength == 1)
return AddrDelta;
if (AddrDelta % MinInsnLength != 0) {
// TODO: report this error, but really only once.
;
}
return AddrDelta / MinInsnLength;
}
//
// 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.
//
void MCDwarfLineEntry::make(MCStreamer *MCOS, MCSection *Section) {
if (!MCOS->getContext().getDwarfLocSeen())
return;
// Create a symbol at in the current section for use in the line entry.
MCSymbol *LineSym = MCOS->getContext().createTempSymbol();
// Set the value of the symbol to use for the MCDwarfLineEntry.
MCOS->emitLabel(LineSym);
// Get the current .loc info saved in the context.
const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();
// Create a (local) line entry with the symbol and the current .loc info.
MCDwarfLineEntry LineEntry(LineSym, DwarfLoc);
// clear DwarfLocSeen saying the current .loc info is now used.
MCOS->getContext().clearDwarfLocSeen();
// Add the line entry to this section's entries.
MCOS->getContext()
.getMCDwarfLineTable(MCOS->getContext().getDwarfCompileUnitID())
.getMCLineSections()
.addLineEntry(LineEntry, Section);
}
//
// This helper routine returns an expression of End - Start + IntVal .
//
static inline const MCExpr *makeEndMinusStartExpr(MCContext &Ctx,
const MCSymbol &Start,
const MCSymbol &End,
int IntVal) {
MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
const MCExpr *Res = MCSymbolRefExpr::create(&End, Variant, Ctx);
const MCExpr *RHS = MCSymbolRefExpr::create(&Start, Variant, Ctx);
const MCExpr *Res1 = MCBinaryExpr::create(MCBinaryExpr::Sub, Res, RHS, Ctx);
const MCExpr *Res2 = MCConstantExpr::create(IntVal, Ctx);
const MCExpr *Res3 = MCBinaryExpr::create(MCBinaryExpr::Sub, Res1, Res2, Ctx);
return Res3;
}
//
// This helper routine returns an expression of Start + IntVal .
//
static inline const MCExpr *
makeStartPlusIntExpr(MCContext &Ctx, const MCSymbol &Start, int IntVal) {
MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
const MCExpr *LHS = MCSymbolRefExpr::create(&Start, Variant, Ctx);
const MCExpr *RHS = MCConstantExpr::create(IntVal, Ctx);
const MCExpr *Res = MCBinaryExpr::create(MCBinaryExpr::Add, LHS, RHS, Ctx);
return Res;
}
//
// This emits the Dwarf line table for the specified section from the entries
// in the LineSection.
//
static inline void emitDwarfLineTable(
MCStreamer *MCOS, MCSection *Section,
const MCLineSection::MCDwarfLineEntryCollection &LineEntries) {
unsigned FileNum = 1;
unsigned LastLine = 1;
unsigned Column = 0;
unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
unsigned Isa = 0;
unsigned Discriminator = 0;
MCSymbol *LastLabel = nullptr;
// Loop through each MCDwarfLineEntry and encode the dwarf line number table.
for (const MCDwarfLineEntry &LineEntry : LineEntries) {
int64_t LineDelta = static_cast<int64_t>(LineEntry.getLine()) - LastLine;
if (FileNum != LineEntry.getFileNum()) {
FileNum = LineEntry.getFileNum();
MCOS->emitInt8(dwarf::DW_LNS_set_file);
MCOS->emitULEB128IntValue(FileNum);
}
if (Column != LineEntry.getColumn()) {
Column = LineEntry.getColumn();
MCOS->emitInt8(dwarf::DW_LNS_set_column);
MCOS->emitULEB128IntValue(Column);
}
if (Discriminator != LineEntry.getDiscriminator() &&
MCOS->getContext().getDwarfVersion() >= 4) {
Discriminator = LineEntry.getDiscriminator();
unsigned Size = getULEB128Size(Discriminator);
MCOS->emitInt8(dwarf::DW_LNS_extended_op);
MCOS->emitULEB128IntValue(Size + 1);
MCOS->emitInt8(dwarf::DW_LNE_set_discriminator);
MCOS->emitULEB128IntValue(Discriminator);
}
if (Isa != LineEntry.getIsa()) {
Isa = LineEntry.getIsa();
MCOS->emitInt8(dwarf::DW_LNS_set_isa);
MCOS->emitULEB128IntValue(Isa);
}
if ((LineEntry.getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
Flags = LineEntry.getFlags();
MCOS->emitInt8(dwarf::DW_LNS_negate_stmt);
}
if (LineEntry.getFlags() & DWARF2_FLAG_BASIC_BLOCK)
MCOS->emitInt8(dwarf::DW_LNS_set_basic_block);
if (LineEntry.getFlags() & DWARF2_FLAG_PROLOGUE_END)
MCOS->emitInt8(dwarf::DW_LNS_set_prologue_end);
if (LineEntry.getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
MCOS->emitInt8(dwarf::DW_LNS_set_epilogue_begin);
MCSymbol *Label = LineEntry.getLabel();
// At this point we want to emit/create the sequence to encode the delta in
// line numbers and the increment of the address from the previous Label
// and the current Label.
const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
MCOS->emitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label,
asmInfo->getCodePointerSize());
Discriminator = 0;
LastLine = LineEntry.getLine();
LastLabel = Label;
}
// Generate DWARF line end entry.
MCOS->emitDwarfLineEndEntry(Section, LastLabel);
}
//
// This emits the Dwarf file and the line tables.
//
void MCDwarfLineTable::emit(MCStreamer *MCOS, MCDwarfLineTableParams Params) {
MCContext &context = MCOS->getContext();
auto &LineTables = context.getMCDwarfLineTables();
// Bail out early so we don't switch to the debug_line section needlessly and
// in doing so create an unnecessary (if empty) section.
if (LineTables.empty())
return;
// In a v5 non-split line table, put the strings in a separate section.
Optional<MCDwarfLineStr> LineStr;
if (context.getDwarfVersion() >= 5)
LineStr = MCDwarfLineStr(context);
// Switch to the section where the table will be emitted into.
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
// Handle the rest of the Compile Units.
for (const auto &CUIDTablePair : LineTables) {
CUIDTablePair.second.emitCU(MCOS, Params, LineStr);
}
if (LineStr)
LineStr->emitSection(MCOS);
}
void MCDwarfDwoLineTable::Emit(MCStreamer &MCOS, MCDwarfLineTableParams Params,
MCSection *Section) const {
if (!HasSplitLineTable)
return;
Optional<MCDwarfLineStr> NoLineStr(None);
MCOS.SwitchSection(Section);
MCOS.emitLabel(Header.Emit(&MCOS, Params, None, NoLineStr).second);
}
std::pair<MCSymbol *, MCSymbol *>
MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
Optional<MCDwarfLineStr> &LineStr) const {
static const char StandardOpcodeLengths[] = {
0, // length of DW_LNS_copy
1, // length of DW_LNS_advance_pc
1, // length of DW_LNS_advance_line
1, // length of DW_LNS_set_file
1, // length of DW_LNS_set_column
0, // length of DW_LNS_negate_stmt
0, // length of DW_LNS_set_basic_block
0, // length of DW_LNS_const_add_pc
1, // length of DW_LNS_fixed_advance_pc
0, // length of DW_LNS_set_prologue_end
0, // length of DW_LNS_set_epilogue_begin
1 // DW_LNS_set_isa
};
assert(array_lengthof(StandardOpcodeLengths) >=
(Params.DWARF2LineOpcodeBase - 1U));
return Emit(
MCOS, Params,
makeArrayRef(StandardOpcodeLengths, Params.DWARF2LineOpcodeBase - 1),
LineStr);
}
static const MCExpr *forceExpAbs(MCStreamer &OS, const MCExpr* Expr) {
MCContext &Context = OS.getContext();
assert(!isa<MCSymbolRefExpr>(Expr));
if (Context.getAsmInfo()->hasAggressiveSymbolFolding())
return Expr;
MCSymbol *ABS = Context.createTempSymbol();
OS.emitAssignment(ABS, Expr);
return MCSymbolRefExpr::create(ABS, Context);
}
static void emitAbsValue(MCStreamer &OS, const MCExpr *Value, unsigned Size) {
const MCExpr *ABS = forceExpAbs(OS, Value);
OS.emitValue(ABS, Size);
}
void MCDwarfLineStr::emitSection(MCStreamer *MCOS) {
// Switch to the .debug_line_str section.
MCOS->SwitchSection(
MCOS->getContext().getObjectFileInfo()->getDwarfLineStrSection());
// Emit the strings without perturbing the offsets we used.
LineStrings.finalizeInOrder();
SmallString<0> Data;
Data.resize(LineStrings.getSize());
LineStrings.write((uint8_t *)Data.data());
MCOS->emitBinaryData(Data.str());
}
void MCDwarfLineStr::emitRef(MCStreamer *MCOS, StringRef Path) {
int RefSize =
dwarf::getDwarfOffsetByteSize(MCOS->getContext().getDwarfFormat());
size_t Offset = LineStrings.add(Path);
if (UseRelocs) {
MCContext &Ctx = MCOS->getContext();
MCOS->emitValue(makeStartPlusIntExpr(Ctx, *LineStrLabel, Offset), RefSize);
} else
MCOS->emitIntValue(Offset, RefSize);
}
void MCDwarfLineTableHeader::emitV2FileDirTables(MCStreamer *MCOS) const {
// First the directory table.
for (auto &Dir : MCDwarfDirs) {
MCOS->emitBytes(Dir); // The DirectoryName, and...
MCOS->emitBytes(StringRef("\0", 1)); // its null terminator.
}
MCOS->emitInt8(0); // Terminate the directory list.
// Second the file table.
for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
assert(!MCDwarfFiles[i].Name.empty());
MCOS->emitBytes(MCDwarfFiles[i].Name); // FileName and...
MCOS->emitBytes(StringRef("\0", 1)); // its null terminator.
MCOS->emitULEB128IntValue(MCDwarfFiles[i].DirIndex); // Directory number.
MCOS->emitInt8(0); // Last modification timestamp (always 0).
MCOS->emitInt8(0); // File size (always 0).
}
MCOS->emitInt8(0); // Terminate the file list.
}
static void emitOneV5FileEntry(MCStreamer *MCOS, const MCDwarfFile &DwarfFile,
bool EmitMD5, bool HasSource,
Optional<MCDwarfLineStr> &LineStr) {
assert(!DwarfFile.Name.empty());
if (LineStr)
LineStr->emitRef(MCOS, DwarfFile.Name);
else {
MCOS->emitBytes(DwarfFile.Name); // FileName and...
MCOS->emitBytes(StringRef("\0", 1)); // its null terminator.
}
MCOS->emitULEB128IntValue(DwarfFile.DirIndex); // Directory number.
if (EmitMD5) {
const MD5::MD5Result &Cksum = *DwarfFile.Checksum;
MCOS->emitBinaryData(
StringRef(reinterpret_cast<const char *>(Cksum.Bytes.data()),
Cksum.Bytes.size()));
}
if (HasSource) {
if (LineStr)
LineStr->emitRef(MCOS, DwarfFile.Source.getValueOr(StringRef()));
else {
MCOS->emitBytes(
DwarfFile.Source.getValueOr(StringRef())); // Source and...
MCOS->emitBytes(StringRef("\0", 1)); // its null terminator.
}
}
}
void MCDwarfLineTableHeader::emitV5FileDirTables(
MCStreamer *MCOS, Optional<MCDwarfLineStr> &LineStr) const {
// The directory format, which is just a list of the directory paths. In a
// non-split object, these are references to .debug_line_str; in a split
// object, they are inline strings.
MCOS->emitInt8(1);
MCOS->emitULEB128IntValue(dwarf::DW_LNCT_path);
MCOS->emitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp
: dwarf::DW_FORM_string);
MCOS->emitULEB128IntValue(MCDwarfDirs.size() + 1);
// Try not to emit an empty compilation directory.
const StringRef CompDir = CompilationDir.empty()
? MCOS->getContext().getCompilationDir()
: StringRef(CompilationDir);
if (LineStr) {
// Record path strings, emit references here.
LineStr->emitRef(MCOS, CompDir);
for (const auto &Dir : MCDwarfDirs)
LineStr->emitRef(MCOS, Dir);
} else {
// The list of directory paths. Compilation directory comes first.
MCOS->emitBytes(CompDir);
MCOS->emitBytes(StringRef("\0", 1));
for (const auto &Dir : MCDwarfDirs) {
MCOS->emitBytes(Dir); // The DirectoryName, and...
MCOS->emitBytes(StringRef("\0", 1)); // its null terminator.
}
}
// The file format, which is the inline null-terminated filename and a
// directory index. We don't track file size/timestamp so don't emit them
// in the v5 table. Emit MD5 checksums and source if we have them.
uint64_t Entries = 2;
if (HasAllMD5)
Entries += 1;
if (HasSource)
Entries += 1;
MCOS->emitInt8(Entries);
MCOS->emitULEB128IntValue(dwarf::DW_LNCT_path);
MCOS->emitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp
: dwarf::DW_FORM_string);
MCOS->emitULEB128IntValue(dwarf::DW_LNCT_directory_index);
MCOS->emitULEB128IntValue(dwarf::DW_FORM_udata);
if (HasAllMD5) {
MCOS->emitULEB128IntValue(dwarf::DW_LNCT_MD5);
MCOS->emitULEB128IntValue(dwarf::DW_FORM_data16);
}
if (HasSource) {
MCOS->emitULEB128IntValue(dwarf::DW_LNCT_LLVM_source);
MCOS->emitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp
: dwarf::DW_FORM_string);
}
// Then the counted list of files. The root file is file #0, then emit the
// files as provide by .file directives.
// MCDwarfFiles has an unused element [0] so use size() not size()+1.
// But sometimes MCDwarfFiles is empty, in which case we still emit one file.
MCOS->emitULEB128IntValue(MCDwarfFiles.empty() ? 1 : MCDwarfFiles.size());
// To accommodate assembler source written for DWARF v4 but trying to emit
// v5: If we didn't see a root file explicitly, replicate file #1.
assert((!RootFile.Name.empty() || MCDwarfFiles.size() >= 1) &&
"No root file and no .file directives");
emitOneV5FileEntry(MCOS, RootFile.Name.empty() ? MCDwarfFiles[1] : RootFile,
HasAllMD5, HasSource, LineStr);
for (unsigned i = 1; i < MCDwarfFiles.size(); ++i)
emitOneV5FileEntry(MCOS, MCDwarfFiles[i], HasAllMD5, HasSource, LineStr);
}
std::pair<MCSymbol *, MCSymbol *>
MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
ArrayRef<char> StandardOpcodeLengths,
Optional<MCDwarfLineStr> &LineStr) const {
MCContext &context = MCOS->getContext();
// Create a symbol at the beginning of the line table.
MCSymbol *LineStartSym = Label;
if (!LineStartSym)
LineStartSym = context.createTempSymbol();
// Set the value of the symbol, as we are at the start of the line table.
MCOS->emitDwarfLineStartLabel(LineStartSym);
unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(context.getDwarfFormat());
MCSymbol *LineEndSym = MCOS->emitDwarfUnitLength("debug_line", "unit length");
// Next 2 bytes is the Version.
unsigned LineTableVersion = context.getDwarfVersion();
MCOS->emitInt16(LineTableVersion);
// In v5, we get address info next.
if (LineTableVersion >= 5) {
MCOS->emitInt8(context.getAsmInfo()->getCodePointerSize());
MCOS->emitInt8(0); // Segment selector; same as EmitGenDwarfAranges.
}
// Create symbols for the start/end of the prologue.
MCSymbol *ProStartSym = context.createTempSymbol("prologue_start");
MCSymbol *ProEndSym = context.createTempSymbol("prologue_end");
// Length of the prologue, is the next 4 bytes (8 bytes for DWARF64). This is
// actually the length from after the length word, to the end of the prologue.
MCOS->emitAbsoluteSymbolDiff(ProEndSym, ProStartSym, OffsetSize);
MCOS->emitLabel(ProStartSym);
// Parameters of the state machine, are next.
MCOS->emitInt8(context.getAsmInfo()->getMinInstAlignment());
// maximum_operations_per_instruction
// For non-VLIW architectures this field is always 1.
// FIXME: VLIW architectures need to update this field accordingly.
if (LineTableVersion >= 4)
MCOS->emitInt8(1);
MCOS->emitInt8(DWARF2_LINE_DEFAULT_IS_STMT);
MCOS->emitInt8(Params.DWARF2LineBase);
MCOS->emitInt8(Params.DWARF2LineRange);
MCOS->emitInt8(StandardOpcodeLengths.size() + 1);
// Standard opcode lengths
for (char Length : StandardOpcodeLengths)
MCOS->emitInt8(Length);
// Put out the directory and file tables. The formats vary depending on
// the version.
if (LineTableVersion >= 5)
emitV5FileDirTables(MCOS, LineStr);
else
emitV2FileDirTables(MCOS);
// This is the end of the prologue, so set the value of the symbol at the
// end of the prologue (that was used in a previous expression).
MCOS->emitLabel(ProEndSym);
return std::make_pair(LineStartSym, LineEndSym);
}
void MCDwarfLineTable::emitCU(MCStreamer *MCOS, MCDwarfLineTableParams Params,
Optional<MCDwarfLineStr> &LineStr) const {
MCSymbol *LineEndSym = Header.Emit(MCOS, Params, LineStr).second;
// Put out the line tables.
for (const auto &LineSec : MCLineSections.getMCLineEntries())
emitDwarfLineTable(MCOS, LineSec.first, LineSec.second);
// This is the end of the section, so set the value of the symbol at the end
// of this section (that was used in a previous expression).
MCOS->emitLabel(LineEndSym);
}
Expected<unsigned> MCDwarfLineTable::tryGetFile(StringRef &Directory,
StringRef &FileName,
Optional<MD5::MD5Result> Checksum,
Optional<StringRef> Source,
uint16_t DwarfVersion,
unsigned FileNumber) {
return Header.tryGetFile(Directory, FileName, Checksum, Source, DwarfVersion,
FileNumber);
}
static bool isRootFile(const MCDwarfFile &RootFile, StringRef &Directory,
StringRef &FileName, Optional<MD5::MD5Result> Checksum) {
if (RootFile.Name.empty() || RootFile.Name != FileName.data())
return false;
return RootFile.Checksum == Checksum;
}
Expected<unsigned>
MCDwarfLineTableHeader::tryGetFile(StringRef &Directory,
StringRef &FileName,
Optional<MD5::MD5Result> Checksum,
Optional<StringRef> Source,
uint16_t DwarfVersion,
unsigned FileNumber) {
if (Directory == CompilationDir)
Directory = "";
if (FileName.empty()) {
FileName = "<stdin>";
Directory = "";
}
assert(!FileName.empty());
// Keep track of whether any or all files have an MD5 checksum.
// If any files have embedded source, they all must.
if (MCDwarfFiles.empty()) {
trackMD5Usage(Checksum.hasValue());
HasSource = (Source != None);
}
if (isRootFile(RootFile, Directory, FileName, Checksum) && DwarfVersion >= 5)
return 0;
if (FileNumber == 0) {
// File numbers start with 1 and/or after any file numbers
// allocated by inline-assembler .file directives.
FileNumber = MCDwarfFiles.empty() ? 1 : MCDwarfFiles.size();
SmallString<256> Buffer;
auto IterBool = SourceIdMap.insert(
std::make_pair((Directory + Twine('\0') + FileName).toStringRef(Buffer),
FileNumber));
if (!IterBool.second)
return IterBool.first->second;
}
// Make space for this FileNumber in the MCDwarfFiles vector if needed.
if (FileNumber >= MCDwarfFiles.size())
MCDwarfFiles.resize(FileNumber + 1);
// Get the new MCDwarfFile slot for this FileNumber.
MCDwarfFile &File = MCDwarfFiles[FileNumber];
// It is an error to see the same number more than once.
if (!File.Name.empty())
return make_error<StringError>("file number already allocated",
inconvertibleErrorCode());
// If any files have embedded source, they all must.
if (HasSource != (Source != None))
return make_error<StringError>("inconsistent use of embedded source",
inconvertibleErrorCode());
if (Directory.empty()) {
// Separate the directory part from the basename of the FileName.
StringRef tFileName = sys::path::filename(FileName);
if (!tFileName.empty()) {
Directory = sys::path::parent_path(FileName);
if (!Directory.empty())
FileName = tFileName;
}
}
// Find or make an entry in the MCDwarfDirs vector for this Directory.
// Capture directory name.
unsigned DirIndex;
if (Directory.empty()) {
// For FileNames with no directories a DirIndex of 0 is used.
DirIndex = 0;
} else {
DirIndex = llvm::find(MCDwarfDirs, Directory) - MCDwarfDirs.begin();
if (DirIndex >= MCDwarfDirs.size())
MCDwarfDirs.push_back(std::string(Directory));
// The DirIndex is one based, as DirIndex of 0 is used for FileNames with
// no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the
// directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames
// are stored at MCDwarfFiles[FileNumber].Name .
DirIndex++;
}
File.Name = std::string(FileName);
File.DirIndex = DirIndex;
File.Checksum = Checksum;
trackMD5Usage(Checksum.hasValue());
File.Source = Source;
if (Source)
HasSource = true;
// return the allocated FileNumber.
return FileNumber;
}
/// Utility function to emit the encoding to a streamer.
void MCDwarfLineAddr::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
int64_t LineDelta, uint64_t AddrDelta) {
MCContext &Context = MCOS->getContext();
SmallString<256> Tmp;
raw_svector_ostream OS(Tmp);
MCDwarfLineAddr::Encode(Context, Params, LineDelta, AddrDelta, OS);
MCOS->emitBytes(OS.str());
}
/// Given a special op, return the address skip amount (in units of
/// DWARF2_LINE_MIN_INSN_LENGTH).
static uint64_t SpecialAddr(MCDwarfLineTableParams Params, uint64_t op) {
return (op - Params.DWARF2LineOpcodeBase) / Params.DWARF2LineRange;
}
/// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
void MCDwarfLineAddr::Encode(MCContext &Context, MCDwarfLineTableParams Params,
int64_t LineDelta, uint64_t AddrDelta,
raw_ostream &OS) {
uint64_t Temp, Opcode;
bool NeedCopy = false;
// The maximum address skip amount that can be encoded with a special op.
uint64_t MaxSpecialAddrDelta = SpecialAddr(Params, 255);
// Scale the address delta by the minimum instruction length.
AddrDelta = ScaleAddrDelta(Context, AddrDelta);
// A LineDelta of INT64_MAX is a signal that this is actually a
// DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
// end_sequence to emit the matrix entry.
if (LineDelta == INT64_MAX) {
if (AddrDelta == MaxSpecialAddrDelta)
OS << char(dwarf::DW_LNS_const_add_pc);
else if (AddrDelta) {
OS << char(dwarf::DW_LNS_advance_pc);
encodeULEB128(AddrDelta, OS);
}
OS << char(dwarf::DW_LNS_extended_op);
OS << char(1);
OS << char(dwarf::DW_LNE_end_sequence);
return;
}
// Bias the line delta by the base.
Temp = LineDelta - Params.DWARF2LineBase;
// If the line increment is out of range of a special opcode, we must encode
// it with DW_LNS_advance_line.
if (Temp >= Params.DWARF2LineRange ||
Temp + Params.DWARF2LineOpcodeBase > 255) {
OS << char(dwarf::DW_LNS_advance_line);
encodeSLEB128(LineDelta, OS);
LineDelta = 0;
Temp = 0 - Params.DWARF2LineBase;
NeedCopy = true;
}
// Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
if (LineDelta == 0 && AddrDelta == 0) {
OS << char(dwarf::DW_LNS_copy);
return;
}
// Bias the opcode by the special opcode base.
Temp += Params.DWARF2LineOpcodeBase;
// Avoid overflow when addr_delta is large.
if (AddrDelta < 256 + MaxSpecialAddrDelta) {
// Try using a special opcode.
Opcode = Temp + AddrDelta * Params.DWARF2LineRange;
if (Opcode <= 255) {
OS << char(Opcode);
return;
}
// Try using DW_LNS_const_add_pc followed by special op.
Opcode = Temp + (AddrDelta - MaxSpecialAddrDelta) * Params.DWARF2LineRange;
if (Opcode <= 255) {
OS << char(dwarf::DW_LNS_const_add_pc);
OS << char(Opcode);
return;
}
}
// Otherwise use DW_LNS_advance_pc.
OS << char(dwarf::DW_LNS_advance_pc);
encodeULEB128(AddrDelta, OS);
if (NeedCopy)
OS << char(dwarf::DW_LNS_copy);
else {
assert(Temp <= 255 && "Buggy special opcode encoding.");
OS << char(Temp);
}
}
std::tuple<uint32_t, uint32_t, bool>
MCDwarfLineAddr::fixedEncode(MCContext &Context, int64_t LineDelta,
uint64_t AddrDelta, raw_ostream &OS) {
uint32_t Offset, Size;
if (LineDelta != INT64_MAX) {
OS << char(dwarf::DW_LNS_advance_line);
encodeSLEB128(LineDelta, OS);
}
// Use address delta to adjust address or use absolute address to adjust
// address.
bool SetDelta;
// According to DWARF spec., the DW_LNS_fixed_advance_pc opcode takes a
// single uhalf (unencoded) operand. So, the maximum value of AddrDelta
// is 65535. We set a conservative upper bound for it for relaxation.
if (AddrDelta > 60000) {
const MCAsmInfo *asmInfo = Context.getAsmInfo();
unsigned AddrSize = asmInfo->getCodePointerSize();
OS << char(dwarf::DW_LNS_extended_op);
encodeULEB128(1 + AddrSize, OS);
OS << char(dwarf::DW_LNE_set_address);
// Generate fixup for the address.
Offset = OS.tell();
Size = AddrSize;
SetDelta = false;
OS.write_zeros(AddrSize);
} else {
OS << char(dwarf::DW_LNS_fixed_advance_pc);
// Generate fixup for 2-bytes address delta.
Offset = OS.tell();
Size = 2;
SetDelta = true;
OS << char(0);
OS << char(0);
}
if (LineDelta == INT64_MAX) {
OS << char(dwarf::DW_LNS_extended_op);
OS << char(1);
OS << char(dwarf::DW_LNE_end_sequence);
} else {
OS << char(dwarf::DW_LNS_copy);
}
return std::make_tuple(Offset, Size, SetDelta);
}
// 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->emitInt8(dwarf::DW_CHILDREN_yes);
dwarf::Form SecOffsetForm =
context.getDwarfVersion() >= 4
? dwarf::DW_FORM_sec_offset
: (context.getDwarfFormat() == dwarf::DWARF64 ? dwarf::DW_FORM_data8
: dwarf::DW_FORM_data4);
EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, SecOffsetForm);
if (context.getGenDwarfSectionSyms().size() > 1 &&
context.getDwarfVersion() >= 3) {
EmitAbbrev(MCOS, dwarf::DW_AT_ranges, SecOffsetForm);
} else {
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);
if (!context.getCompilationDir().empty())
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_label DIE abbrev (2).
MCOS->emitULEB128IntValue(2);
MCOS->emitULEB128IntValue(dwarf::DW_TAG_label);
MCOS->emitInt8(dwarf::DW_CHILDREN_no);
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, 0, 0);
// Terminate the abbreviations for this compilation unit.
MCOS->emitInt8(0);
}
// When generating dwarf for assembly source files this emits the data for
// .debug_aranges section. This section contains a header and a table of pairs
// of PointerSize'ed values for the address and size of section(s) with line
// table entries.
static void EmitGenDwarfAranges(MCStreamer *MCOS,
const MCSymbol *InfoSectionSymbol) {
MCContext &context = MCOS->getContext();
auto &Sections = context.getGenDwarfSectionSyms();
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
unsigned UnitLengthBytes =
dwarf::getUnitLengthFieldByteSize(context.getDwarfFormat());
unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(context.getDwarfFormat());
// 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 = UnitLengthBytes + 2 + OffsetSize + 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->getCodePointerSize();
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 each section we have in the table.
Length += 2 * AddrSize * Sections.size();
// And the pair of terminating zeros.
Length += 2 * AddrSize;
// Emit the header for this section.
if (context.getDwarfFormat() == dwarf::DWARF64)
// The DWARF64 mark.
MCOS->emitInt32(dwarf::DW_LENGTH_DWARF64);
// The 4 (8 for DWARF64) byte length not including the length of the unit
// length field itself.
MCOS->emitIntValue(Length - UnitLengthBytes, OffsetSize);
// The 2 byte version, which is 2.
MCOS->emitInt16(2);
// The 4 (8 for DWARF64) byte offset to the compile unit in the .debug_info
// from the start of the .debug_info.
if (InfoSectionSymbol)
MCOS->emitSymbolValue(InfoSectionSymbol, OffsetSize,
asmInfo->needsDwarfSectionOffsetDirective());
else
MCOS->emitIntValue(0, OffsetSize);
// The 1 byte size of an address.
MCOS->emitInt8(AddrSize);
// The 1 byte size of a segment descriptor, we use a value of zero.
MCOS->emitInt8(0);
// Align the header with the padding if needed, before we put out the table.
for(int i = 0; i < Pad; i++)
MCOS->emitInt8(0);
// Now emit the table of pairs of PointerSize'ed values for the section
// addresses and sizes.
for (MCSection *Sec : Sections) {
const MCSymbol *StartSymbol = Sec->getBeginSymbol();
MCSymbol *EndSymbol = Sec->getEndSymbol(context);
assert(StartSymbol && "StartSymbol must not be NULL");
assert(EndSymbol && "EndSymbol must not be NULL");
const MCExpr *Addr = MCSymbolRefExpr::create(
StartSymbol, MCSymbolRefExpr::VK_None, context);
const MCExpr *Size =
makeEndMinusStartExpr(context, *StartSymbol, *EndSymbol, 0);
MCOS->emitValue(Addr, AddrSize);
emitAbsValue(*MCOS, 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 label DIEs.
static void EmitGenDwarfInfo(MCStreamer *MCOS,
const MCSymbol *AbbrevSectionSymbol,
const MCSymbol *LineSectionSymbol,
const MCSymbol *RangesSymbol) {
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.
unsigned UnitLengthBytes =
dwarf::getUnitLengthFieldByteSize(context.getDwarfFormat());
unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(context.getDwarfFormat());
if (context.getDwarfFormat() == dwarf::DWARF64)
// Emit DWARF64 mark.
MCOS->emitInt32(dwarf::DW_LENGTH_DWARF64);
// The 4 (8 for DWARF64) byte total length of the information for this
// compilation unit, not including the unit length field itself.
const MCExpr *Length =
makeEndMinusStartExpr(context, *InfoStart, *InfoEnd, UnitLengthBytes);
emitAbsValue(*MCOS, Length, OffsetSize);
// The 2 byte DWARF version.
MCOS->emitInt16(context.getDwarfVersion());
// The DWARF v5 header has unit type, address size, abbrev offset.
// Earlier versions have abbrev offset, address size.
const MCAsmInfo &AsmInfo = *context.getAsmInfo();
int AddrSize = AsmInfo.getCodePointerSize();
if (context.getDwarfVersion() >= 5) {
MCOS->emitInt8(dwarf::DW_UT_compile);
MCOS->emitInt8(AddrSize);
}
// The 4 (8 for DWARF64) byte offset to the debug abbrevs from the start of
// the .debug_abbrev.
if (AbbrevSectionSymbol)
MCOS->emitSymbolValue(AbbrevSectionSymbol, OffsetSize,
AsmInfo.needsDwarfSectionOffsetDirective());
else
// Since the abbrevs are at the start of the section, the offset is zero.
MCOS->emitIntValue(0, OffsetSize);
if (context.getDwarfVersion() <= 4)
MCOS->emitInt8(AddrSize);
// Second part: the compile_unit DIE.
// The DW_TAG_compile_unit DIE abbrev (1).
MCOS->emitULEB128IntValue(1);
// DW_AT_stmt_list, a 4 (8 for DWARF64) byte offset from the start of the
// .debug_line section.
if (LineSectionSymbol)
MCOS->emitSymbolValue(LineSectionSymbol, OffsetSize,
AsmInfo.needsDwarfSectionOffsetDirective());
else
// The line table is at the start of the section, so the offset is zero.
MCOS->emitIntValue(0, OffsetSize);
if (RangesSymbol) {
// There are multiple sections containing code, so we must use
// .debug_ranges/.debug_rnglists. AT_ranges, the 4/8 byte offset from the
// start of the .debug_ranges/.debug_rnglists.
MCOS->emitSymbolValue(RangesSymbol, OffsetSize);
} else {
// If we only have one non-empty code section, we can use the simpler
// AT_low_pc and AT_high_pc attributes.
// Find the first (and only) non-empty text section
auto &Sections = context.getGenDwarfSectionSyms();
const auto TextSection = Sections.begin();
assert(TextSection != Sections.end() && "No text section found");
MCSymbol *StartSymbol = (*TextSection)->getBeginSymbol();
MCSymbol *EndSymbol = (*TextSection)->getEndSymbol(context);
assert(StartSymbol && "StartSymbol must not be NULL");
assert(EndSymbol && "EndSymbol must not be NULL");
// AT_low_pc, the first address of the default .text section.
const MCExpr *Start = MCSymbolRefExpr::create(
StartSymbol, MCSymbolRefExpr::VK_None, context);
MCOS->emitValue(Start, AddrSize);
// AT_high_pc, the last address of the default .text section.
const MCExpr *End = MCSymbolRefExpr::create(
EndSymbol, MCSymbolRefExpr::VK_None, context);
MCOS->emitValue(End, AddrSize);
}
// AT_name, the name of the source file. Reconstruct from the first directory
// and file table entries.
const SmallVectorImpl<std::string> &MCDwarfDirs = context.getMCDwarfDirs();
if (MCDwarfDirs.size() > 0) {
MCOS->emitBytes(MCDwarfDirs[0]);
MCOS->emitBytes(sys::path::get_separator());
}
const SmallVectorImpl<MCDwarfFile> &MCDwarfFiles = context.getMCDwarfFiles();
// MCDwarfFiles might be empty if we have an empty source file.
// If it's not empty, [0] is unused and [1] is the first actual file.
assert(MCDwarfFiles.empty() || MCDwarfFiles.size() >= 2);
const MCDwarfFile &RootFile =
MCDwarfFiles.empty()
? context.getMCDwarfLineTable(/*CUID=*/0).getRootFile()
: MCDwarfFiles[1];
MCOS->emitBytes(RootFile.Name);
MCOS->emitInt8(0); // NULL byte to terminate the string.
// AT_comp_dir, the working directory the assembly was done in.
if (!context.getCompilationDir().empty()) {
MCOS->emitBytes(context.getCompilationDir());
MCOS->emitInt8(0); // 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);
MCOS->emitInt8(0); // NULL byte to terminate the string.
}
// AT_producer, the version of the assembler tool.
StringRef DwarfDebugProducer = context.getDwarfDebugProducer();
if (!DwarfDebugProducer.empty())
MCOS->emitBytes(DwarfDebugProducer);
else
MCOS->emitBytes(StringRef("llvm-mc (based on LLVM " PACKAGE_VERSION ")"));
MCOS->emitInt8(0); // 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->emitInt16(dwarf::DW_LANG_Mips_Assembler);
// Third part: the list of label DIEs.
// Loop on saved info for dwarf labels and create the DIEs for them.
const std::vector<MCGenDwarfLabelEntry> &Entries =
MCOS->getContext().getMCGenDwarfLabelEntries();
for (const auto &Entry : Entries) {
// The DW_TAG_label DIE abbrev (2).
MCOS->emitULEB128IntValue(2);
// AT_name, of the label without any leading underbar.
MCOS->emitBytes(Entry.getName());
MCOS->emitInt8(0); // NULL byte to terminate the string.
// AT_decl_file, index into the file table.
MCOS->emitInt32(Entry.getFileNumber());
// AT_decl_line, source line number.
MCOS->emitInt32(Entry.getLineNumber());
// AT_low_pc, start address of the label.
const MCExpr *AT_low_pc = MCSymbolRefExpr::create(Entry.getLabel(),
MCSymbolRefExpr::VK_None, context);
MCOS->emitValue(AT_low_pc, AddrSize);
}
// Add the NULL DIE terminating the Compile Unit DIE's.
MCOS->emitInt8(0);
// 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 data for
// .debug_ranges section. We only emit one range list, which spans all of the
// executable sections of this file.
static MCSymbol *emitGenDwarfRanges(MCStreamer *MCOS) {
MCContext &context = MCOS->getContext();
auto &Sections = context.getGenDwarfSectionSyms();
const MCAsmInfo *AsmInfo = context.getAsmInfo();
int AddrSize = AsmInfo->getCodePointerSize();
MCSymbol *RangesSymbol;
if (MCOS->getContext().getDwarfVersion() >= 5) {
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRnglistsSection());
MCSymbol *EndSymbol = mcdwarf::emitListsTableHeaderStart(*MCOS);
MCOS->AddComment("Offset entry count");
MCOS->emitInt32(0);
RangesSymbol = context.createTempSymbol("debug_rnglist0_start");
MCOS->emitLabel(RangesSymbol);
for (MCSection *Sec : Sections) {
const MCSymbol *StartSymbol = Sec->getBeginSymbol();
const MCSymbol *EndSymbol = Sec->getEndSymbol(context);
const MCExpr *SectionStartAddr = MCSymbolRefExpr::create(
StartSymbol, MCSymbolRefExpr::VK_None, context);
const MCExpr *SectionSize =
makeEndMinusStartExpr(context, *StartSymbol, *EndSymbol, 0);
MCOS->emitInt8(dwarf::DW_RLE_start_length);
MCOS->emitValue(SectionStartAddr, AddrSize);
MCOS->emitULEB128Value(SectionSize);
}
MCOS->emitInt8(dwarf::DW_RLE_end_of_list);
MCOS->emitLabel(EndSymbol);
} else {
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
RangesSymbol = context.createTempSymbol("debug_ranges_start");
MCOS->emitLabel(RangesSymbol);
for (MCSection *Sec : Sections) {
const MCSymbol *StartSymbol = Sec->getBeginSymbol();
const MCSymbol *EndSymbol = Sec->getEndSymbol(context);
// Emit a base address selection entry for the section start.
const MCExpr *SectionStartAddr = MCSymbolRefExpr::create(
StartSymbol, MCSymbolRefExpr::VK_None, context);
MCOS->emitFill(AddrSize, 0xFF);
MCOS->emitValue(SectionStartAddr, AddrSize);
// Emit a range list entry spanning this section.
const MCExpr *SectionSize =
makeEndMinusStartExpr(context, *StartSymbol, *EndSymbol, 0);
MCOS->emitIntValue(0, AddrSize);
emitAbsValue(*MCOS, SectionSize, AddrSize);
}
// Emit end of list entry
MCOS->emitIntValue(0, AddrSize);
MCOS->emitIntValue(0, AddrSize);
}
return RangesSymbol;
}
//
// When generating dwarf for assembly source files this emits the Dwarf
// sections.
//
void MCGenDwarfInfo::Emit(MCStreamer *MCOS) {
MCContext &context = MCOS->getContext();
// Create the dwarf sections in this order (.debug_line already created).
const MCAsmInfo *AsmInfo = context.getAsmInfo();
bool CreateDwarfSectionSymbols =
AsmInfo->doesDwarfUseRelocationsAcrossSections();
MCSymbol *LineSectionSymbol = nullptr;
if (CreateDwarfSectionSymbols)
LineSectionSymbol = MCOS->getDwarfLineTableSymbol(0);
MCSymbol *AbbrevSectionSymbol = nullptr;
MCSymbol *InfoSectionSymbol = nullptr;
MCSymbol *RangesSymbol = nullptr;
// Create end symbols for each section, and remove empty sections
MCOS->getContext().finalizeDwarfSections(*MCOS);
// If there are no sections to generate debug info for, we don't need
// to do anything
if (MCOS->getContext().getGenDwarfSectionSyms().empty())
return;
// We only use the .debug_ranges section if we have multiple code sections,
// and we are emitting a DWARF version which supports it.
const bool UseRangesSection =
MCOS->getContext().getGenDwarfSectionSyms().size() > 1 &&
MCOS->getContext().getDwarfVersion() >= 3;
CreateDwarfSectionSymbols |= UseRangesSection;
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
if (CreateDwarfSectionSymbols) {
InfoSectionSymbol = context.createTempSymbol();
MCOS->emitLabel(InfoSectionSymbol);
}
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
if (CreateDwarfSectionSymbols) {
AbbrevSectionSymbol = context.createTempSymbol();
MCOS->emitLabel(AbbrevSectionSymbol);
}
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
// Output the data for .debug_aranges section.
EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
if (UseRangesSection) {
RangesSymbol = emitGenDwarfRanges(MCOS);
assert(RangesSymbol);
}
// Output the data for .debug_abbrev section.
EmitGenDwarfAbbrev(MCOS);
// Output the data for .debug_info section.
EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol, RangesSymbol);
}
//
// 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 label.
//
void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS,
SourceMgr &SrcMgr, SMLoc &Loc) {
// We won't create dwarf labels for temporary symbols.
if (Symbol->isTemporary())
return;
MCContext &context = MCOS->getContext();
// We won't create dwarf labels for symbols in sections that we are not
// generating debug info for.
if (!context.getGenDwarfSectionSyms().count(MCOS->getCurrentSectionOnly()))
return;
// The dwarf label'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 label.
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 label.
unsigned 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.
MCOS->getContext().addMCGenDwarfLabelEntry(
MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label));
}
static int getDataAlignmentFactor(MCStreamer &streamer) {
MCContext &context = streamer.getContext();
const MCAsmInfo *asmInfo = context.getAsmInfo();
int size = asmInfo->getCalleeSaveStackSlotSize();
if (asmInfo->isStackGrowthDirectionUp())
return size;
else
return -size;
}
static unsigned getSizeForEncoding(MCStreamer &streamer,
unsigned symbolEncoding) {
MCContext &context = streamer.getContext();
unsigned format = symbolEncoding & 0x0f;
switch (format) {
default: llvm_unreachable("Unknown Encoding");
case dwarf::DW_EH_PE_absptr:
case dwarf::DW_EH_PE_signed:
return context.getAsmInfo()->getCodePointerSize();
case dwarf::DW_EH_PE_udata2:
case dwarf::DW_EH_PE_sdata2:
return 2;
case dwarf::DW_EH_PE_udata4:
case dwarf::DW_EH_PE_sdata4:
return 4;
case dwarf::DW_EH_PE_udata8:
case dwarf::DW_EH_PE_sdata8:
return 8;
}
}
static void emitFDESymbol(MCObjectStreamer &streamer, const MCSymbol &symbol,
unsigned symbolEncoding, bool isEH) {
MCContext &context = streamer.getContext();
const MCAsmInfo *asmInfo = context.getAsmInfo();
const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol,
symbolEncoding,
streamer);
unsigned size = getSizeForEncoding(streamer, symbolEncoding);
if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH)
emitAbsValue(streamer, v, size);
else
streamer.emitValue(v, size);
}
static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol,
unsigned symbolEncoding) {
MCContext &context = streamer.getContext();
const MCAsmInfo *asmInfo = context.getAsmInfo();
const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol,
symbolEncoding,
streamer);
unsigned size = getSizeForEncoding(streamer, symbolEncoding);
streamer.emitValue(v, size);
}
namespace {
class FrameEmitterImpl {
int CFAOffset = 0;
int InitialCFAOffset = 0;
bool IsEH;
MCObjectStreamer &Streamer;
public:
FrameEmitterImpl(bool IsEH, MCObjectStreamer &Streamer)
: IsEH(IsEH), Streamer(Streamer) {}
/// Emit the unwind information in a compact way.
void EmitCompactUnwind(const MCDwarfFrameInfo &frame);
const MCSymbol &EmitCIE(const MCDwarfFrameInfo &F);
void EmitFDE(const MCSymbol &cieStart, const MCDwarfFrameInfo &frame,
bool LastInSection, const MCSymbol &SectionStart);
void emitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
MCSymbol *BaseLabel);
void emitCFIInstruction(const MCCFIInstruction &Instr);
};
} // end anonymous namespace
static void emitEncodingByte(MCObjectStreamer &Streamer, unsigned Encoding) {
Streamer.emitInt8(Encoding);
}
void FrameEmitterImpl::emitCFIInstruction(const MCCFIInstruction &Instr) {
int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
auto *MRI = Streamer.getContext().getRegisterInfo();
switch (Instr.getOperation()) {
case MCCFIInstruction::OpRegister: {
unsigned Reg1 = Instr.getRegister();
unsigned Reg2 = Instr.getRegister2();
if (!IsEH) {
Reg1 = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg1);
Reg2 = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg2);
}
Streamer.emitInt8(dwarf::DW_CFA_register);
Streamer.emitULEB128IntValue(Reg1);
Streamer.emitULEB128IntValue(Reg2);
return;
}
case MCCFIInstruction::OpWindowSave:
Streamer.emitInt8(dwarf::DW_CFA_GNU_window_save);
return;
case MCCFIInstruction::OpNegateRAState:
Streamer.emitInt8(dwarf::DW_CFA_AARCH64_negate_ra_state);
return;
case MCCFIInstruction::OpUndefined: {
unsigned Reg = Instr.getRegister();
Streamer.emitInt8(dwarf::DW_CFA_undefined);
Streamer.emitULEB128IntValue(Reg);
return;
}
case MCCFIInstruction::OpAdjustCfaOffset:
case MCCFIInstruction::OpDefCfaOffset: {
const bool IsRelative =
Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
Streamer.emitInt8(dwarf::DW_CFA_def_cfa_offset);
if (IsRelative)
CFAOffset += Instr.getOffset();
else
CFAOffset = Instr.getOffset();
Streamer.emitULEB128IntValue(CFAOffset);
return;
}
case MCCFIInstruction::OpDefCfa: {
unsigned Reg = Instr.getRegister();
if (!IsEH)
Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
Streamer.emitInt8(dwarf::DW_CFA_def_cfa);
Streamer.emitULEB128IntValue(Reg);
CFAOffset = Instr.getOffset();
Streamer.emitULEB128IntValue(CFAOffset);
return;
}
case MCCFIInstruction::OpDefCfaRegister: {
unsigned Reg = Instr.getRegister();
if (!IsEH)
Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
Streamer.emitInt8(dwarf::DW_CFA_def_cfa_register);
Streamer.emitULEB128IntValue(Reg);
return;
}
case MCCFIInstruction::OpOffset:
case MCCFIInstruction::OpRelOffset: {
const bool IsRelative =
Instr.getOperation() == MCCFIInstruction::OpRelOffset;
unsigned Reg = Instr.getRegister();
if (!IsEH)
Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
int Offset = Instr.getOffset();
if (IsRelative)
Offset -= CFAOffset;
Offset = Offset / dataAlignmentFactor;
if (Offset < 0) {
Streamer.emitInt8(dwarf::DW_CFA_offset_extended_sf);
Streamer.emitULEB128IntValue(Reg);
Streamer.emitSLEB128IntValue(Offset);
} else if (Reg < 64) {
Streamer.emitInt8(dwarf::DW_CFA_offset + Reg);
Streamer.emitULEB128IntValue(Offset);
} else {
Streamer.emitInt8(dwarf::DW_CFA_offset_extended);
Streamer.emitULEB128IntValue(Reg);
Streamer.emitULEB128IntValue(Offset);
}
return;
}
case MCCFIInstruction::OpRememberState:
Streamer.emitInt8(dwarf::DW_CFA_remember_state);
return;
case MCCFIInstruction::OpRestoreState:
Streamer.emitInt8(dwarf::DW_CFA_restore_state);
return;
case MCCFIInstruction::OpSameValue: {
unsigned Reg = Instr.getRegister();
Streamer.emitInt8(dwarf::DW_CFA_same_value);
Streamer.emitULEB128IntValue(Reg);
return;
}
case MCCFIInstruction::OpRestore: {
unsigned Reg = Instr.getRegister();
if (!IsEH)
Reg = MRI->getDwarfRegNumFromDwarfEHRegNum(Reg);
if (Reg < 64) {
Streamer.emitInt8(dwarf::DW_CFA_restore | Reg);
} else {
Streamer.emitInt8(dwarf::DW_CFA_restore_extended);
Streamer.emitULEB128IntValue(Reg);
}
return;
}
case MCCFIInstruction::OpGnuArgsSize:
Streamer.emitInt8(dwarf::DW_CFA_GNU_args_size);
Streamer.emitULEB128IntValue(Instr.getOffset());
return;
case MCCFIInstruction::OpEscape:
Streamer.emitBytes(Instr.getValues());
return;
}
llvm_unreachable("Unhandled case in switch");
}
/// Emit frame instructions to describe the layout of the frame.
void FrameEmitterImpl::emitCFIInstructions(ArrayRef<MCCFIInstruction> Instrs,
MCSymbol *BaseLabel) {
for (const MCCFIInstruction &Instr : Instrs) {
MCSymbol *Label = Instr.getLabel();
// Throw out move if the label is invalid.
if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
// Advance row if new location.
if (BaseLabel && Label) {
MCSymbol *ThisSym = Label;
if (ThisSym != BaseLabel) {
Streamer.emitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
BaseLabel = ThisSym;
}
}
emitCFIInstruction(Instr);
}
}
/// Emit the unwind information in a compact way.
void FrameEmitterImpl::EmitCompactUnwind(const MCDwarfFrameInfo &Frame) {
MCContext &Context = Streamer.getContext();
const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
// range-start range-length compact-unwind-enc personality-func lsda
// _foo LfooEnd-_foo 0x00000023 0 0
// _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1
//
// .section __LD,__compact_unwind,regular,debug
//
// # compact unwind for _foo
// .quad _foo
// .set L1,LfooEnd-_foo
// .long L1
// .long 0x01010001
// .quad 0
// .quad 0
//
// # compact unwind for _bar
// .quad _bar
// .set L2,LbarEnd-_bar
// .long L2
// .long 0x01020011
// .quad __gxx_personality
// .quad except_tab1
uint32_t Encoding = Frame.CompactUnwindEncoding;
if (!Encoding) return;
bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly());
// The encoding needs to know we have an LSDA.
if (!DwarfEHFrameOnly && Frame.Lsda)
Encoding |= 0x40000000;
// Range Start
unsigned FDEEncoding = MOFI->getFDEEncoding();
unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
Streamer.emitSymbolValue(Frame.Begin, Size);
// Range Length
const MCExpr *Range =
makeEndMinusStartExpr(Context, *Frame.Begin, *Frame.End, 0);
emitAbsValue(Streamer, Range, 4);
// Compact Encoding
Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
Streamer.emitIntValue(Encoding, Size);
// Personality Function
Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
if (!DwarfEHFrameOnly && Frame.Personality)
Streamer.emitSymbolValue(Frame.Personality, Size);
else
Streamer.emitIntValue(0, Size); // No personality fn
// LSDA
Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
if (!DwarfEHFrameOnly && Frame.Lsda)
Streamer.emitSymbolValue(Frame.Lsda, Size);
else
Streamer.emitIntValue(0, Size); // No LSDA
}
static unsigned getCIEVersion(bool IsEH, unsigned DwarfVersion) {
if (IsEH)
return 1;
switch (DwarfVersion) {
case 2:
return 1;
case 3:
return 3;
case 4:
case 5:
return 4;
}
llvm_unreachable("Unknown version");
}
const MCSymbol &FrameEmitterImpl::EmitCIE(const MCDwarfFrameInfo &Frame) {
MCContext &context = Streamer.getContext();
const MCRegisterInfo *MRI = context.getRegisterInfo();
const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
MCSymbol *sectionStart = context.createTempSymbol();
Streamer.emitLabel(sectionStart);
MCSymbol *sectionEnd = context.createTempSymbol();
dwarf::DwarfFormat Format = IsEH ? dwarf::DWARF32 : context.getDwarfFormat();
unsigned UnitLengthBytes = dwarf::getUnitLengthFieldByteSize(Format);
unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(Format);
bool IsDwarf64 = Format == dwarf::DWARF64;
if (IsDwarf64)
// DWARF64 mark
Streamer.emitInt32(dwarf::DW_LENGTH_DWARF64);
// Length
const MCExpr *Length = makeEndMinusStartExpr(context, *sectionStart,
*sectionEnd, UnitLengthBytes);
emitAbsValue(Streamer, Length, OffsetSize);
// CIE ID
uint64_t CIE_ID =
IsEH ? 0 : (IsDwarf64 ? dwarf::DW64_CIE_ID : dwarf::DW_CIE_ID);
Streamer.emitIntValue(CIE_ID, OffsetSize);
// Version
uint8_t CIEVersion = getCIEVersion(IsEH, context.getDwarfVersion());
Streamer.emitInt8(CIEVersion);
if (IsEH) {
SmallString<8> Augmentation;
Augmentation += "z";
if (Frame.Personality)
Augmentation += "P";
if (Frame.Lsda)
Augmentation += "L";
Augmentation += "R";
if (Frame.IsSignalFrame)
Augmentation += "S";
if (Frame.IsBKeyFrame)
Augmentation += "B";
Streamer.emitBytes(Augmentation);
}
Streamer.emitInt8(0);
if (CIEVersion >= 4) {
// Address Size
Streamer.emitInt8(context.getAsmInfo()->getCodePointerSize());
// Segment Descriptor Size
Streamer.emitInt8(0);
}
// Code Alignment Factor
Streamer.emitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment());
// Data Alignment Factor
Streamer.emitSLEB128IntValue(getDataAlignmentFactor(Streamer));
// Return Address Register
unsigned RAReg = Frame.RAReg;
if (RAReg == static_cast<unsigned>(INT_MAX))
RAReg = MRI->getDwarfRegNum(MRI->getRARegister(), IsEH);
if (CIEVersion == 1) {
assert(RAReg <= 255 &&
"DWARF 2 encodes return_address_register in one byte");
Streamer.emitInt8(RAReg);
} else {
Streamer.emitULEB128IntValue(RAReg);
}
// Augmentation Data Length (optional)
unsigned augmentationLength = 0;
if (IsEH) {
if (Frame.Personality) {
// Personality Encoding
augmentationLength += 1;
// Personality
augmentationLength +=
getSizeForEncoding(Streamer, Frame.PersonalityEncoding);
}
if (Frame.Lsda)
augmentationLength += 1;
// Encoding of the FDE pointers
augmentationLength += 1;
Streamer.emitULEB128IntValue(augmentationLength);
// Augmentation Data (optional)
if (Frame.Personality) {
// Personality Encoding
emitEncodingByte(Streamer, Frame.PersonalityEncoding);
// Personality
EmitPersonality(Streamer, *Frame.Personality, Frame.PersonalityEncoding);
}
if (Frame.Lsda)
emitEncodingByte(Streamer, Frame.LsdaEncoding);
// Encoding of the FDE pointers
emitEncodingByte(Streamer, MOFI->getFDEEncoding());
}
// Initial Instructions
const MCAsmInfo *MAI = context.getAsmInfo();
if (!Frame.IsSimple) {
const std::vector<MCCFIInstruction> &Instructions =
MAI->getInitialFrameState();
emitCFIInstructions(Instructions, nullptr);
}
InitialCFAOffset = CFAOffset;
// Padding
Streamer.emitValueToAlignment(IsEH ? 4 : MAI->getCodePointerSize());
Streamer.emitLabel(sectionEnd);
return *sectionStart;
}
void FrameEmitterImpl::EmitFDE(const MCSymbol &cieStart,
const MCDwarfFrameInfo &frame,
bool LastInSection,
const MCSymbol &SectionStart) {
MCContext &context = Streamer.getContext();
MCSymbol *fdeStart = context.createTempSymbol();
MCSymbol *fdeEnd = context.createTempSymbol();
const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
CFAOffset = InitialCFAOffset;
dwarf::DwarfFormat Format = IsEH ? dwarf::DWARF32 : context.getDwarfFormat();
unsigned OffsetSize = dwarf::getDwarfOffsetByteSize(Format);
if (Format == dwarf::DWARF64)
// DWARF64 mark
Streamer.emitInt32(dwarf::DW_LENGTH_DWARF64);
// Length
const MCExpr *Length = makeEndMinusStartExpr(context, *fdeStart, *fdeEnd, 0);
emitAbsValue(Streamer, Length, OffsetSize);
Streamer.emitLabel(fdeStart);
// CIE Pointer
const MCAsmInfo *asmInfo = context.getAsmInfo();
if (IsEH) {
const MCExpr *offset =
makeEndMinusStartExpr(context, cieStart, *fdeStart, 0);
emitAbsValue(Streamer, offset, OffsetSize);
} else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) {
const MCExpr *offset =
makeEndMinusStartExpr(context, SectionStart, cieStart, 0);
emitAbsValue(Streamer, offset, OffsetSize);
} else {
Streamer.emitSymbolValue(&cieStart, OffsetSize,
asmInfo->needsDwarfSectionOffsetDirective());
}
// PC Begin
unsigned PCEncoding =
IsEH ? MOFI->getFDEEncoding() : (unsigned)dwarf::DW_EH_PE_absptr;
unsigned PCSize = getSizeForEncoding(Streamer, PCEncoding);
emitFDESymbol(Streamer, *frame.Begin, PCEncoding, IsEH);
// PC Range
const MCExpr *Range =
makeEndMinusStartExpr(context, *frame.Begin, *frame.End, 0);
emitAbsValue(Streamer, Range, PCSize);
if (IsEH) {
// Augmentation Data Length
unsigned augmentationLength = 0;
if (frame.Lsda)
augmentationLength += getSizeForEncoding(Streamer, frame.LsdaEncoding);
Streamer.emitULEB128IntValue(augmentationLength);
// Augmentation Data
if (frame.Lsda)
emitFDESymbol(Streamer, *frame.Lsda, frame.LsdaEncoding, true);
}
// Call Frame Instructions
emitCFIInstructions(frame.Instructions, frame.Begin);
// Padding
// The size of a .eh_frame section has to be a multiple of the alignment
// since a null CIE is interpreted as the end. Old systems overaligned
// .eh_frame, so we do too and account for it in the last FDE.
unsigned Align = LastInSection ? asmInfo->getCodePointerSize() : PCSize;
Streamer.emitValueToAlignment(Align);
Streamer.emitLabel(fdeEnd);
}
namespace {
struct CIEKey {
static const CIEKey getEmptyKey() {
return CIEKey(nullptr, 0, -1, false, false, static_cast<unsigned>(INT_MAX),
false);
}
static const CIEKey getTombstoneKey() {
return CIEKey(nullptr, -1, 0, false, false, static_cast<unsigned>(INT_MAX),
false);
}
CIEKey(const MCSymbol *Personality, unsigned PersonalityEncoding,
unsigned LSDAEncoding, bool IsSignalFrame, bool IsSimple,
unsigned RAReg, bool IsBKeyFrame)
: Personality(Personality), PersonalityEncoding(PersonalityEncoding),
LsdaEncoding(LSDAEncoding), IsSignalFrame(IsSignalFrame),
IsSimple(IsSimple), RAReg(RAReg), IsBKeyFrame(IsBKeyFrame) {}
explicit CIEKey(const MCDwarfFrameInfo &Frame)
: Personality(Frame.Personality),
PersonalityEncoding(Frame.PersonalityEncoding),
LsdaEncoding(Frame.LsdaEncoding), IsSignalFrame(Frame.IsSignalFrame),
IsSimple(Frame.IsSimple), RAReg(Frame.RAReg),
IsBKeyFrame(Frame.IsBKeyFrame) {}
StringRef PersonalityName() const {
if (!Personality)
return StringRef();
return Personality->getName();
}
bool operator<(const CIEKey &Other) const {
return std::make_tuple(PersonalityName(), PersonalityEncoding, LsdaEncoding,
IsSignalFrame, IsSimple, RAReg) <
std::make_tuple(Other.PersonalityName(), Other.PersonalityEncoding,
Other.LsdaEncoding, Other.IsSignalFrame,
Other.IsSimple, Other.RAReg);
}
const MCSymbol *Personality;
unsigned PersonalityEncoding;
unsigned LsdaEncoding;
bool IsSignalFrame;
bool IsSimple;
unsigned RAReg;
bool IsBKeyFrame;
};
} // end anonymous namespace
namespace llvm {
template <> struct DenseMapInfo<CIEKey> {
static CIEKey getEmptyKey() { return CIEKey::getEmptyKey(); }
static CIEKey getTombstoneKey() { return CIEKey::getTombstoneKey(); }
static unsigned getHashValue(const CIEKey &Key) {
return static_cast<unsigned>(hash_combine(
Key.Personality, Key.PersonalityEncoding, Key.LsdaEncoding,
Key.IsSignalFrame, Key.IsSimple, Key.RAReg, Key.IsBKeyFrame));
}
static bool isEqual(const CIEKey &LHS, const CIEKey &RHS) {
return LHS.Personality == RHS.Personality &&
LHS.PersonalityEncoding == RHS.PersonalityEncoding &&
LHS.LsdaEncoding == RHS.LsdaEncoding &&
LHS.IsSignalFrame == RHS.IsSignalFrame &&
LHS.IsSimple == RHS.IsSimple && LHS.RAReg == RHS.RAReg &&
LHS.IsBKeyFrame == RHS.IsBKeyFrame;
}
};
} // end namespace llvm
void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
bool IsEH) {
Streamer.generateCompactUnwindEncodings(MAB);
MCContext &Context = Streamer.getContext();
const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
const MCAsmInfo *AsmInfo = Context.getAsmInfo();
FrameEmitterImpl Emitter(IsEH, Streamer);
ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getDwarfFrameInfos();
// Emit the compact unwind info if available.
bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
if (IsEH && MOFI->getCompactUnwindSection()) {
bool SectionEmitted = false;
for (const MCDwarfFrameInfo &Frame : FrameArray) {
if (Frame.CompactUnwindEncoding == 0) continue;
if (!SectionEmitted) {
Streamer.SwitchSection(MOFI->getCompactUnwindSection());
Streamer.emitValueToAlignment(AsmInfo->getCodePointerSize());
SectionEmitted = true;
}
NeedsEHFrameSection |=
Frame.CompactUnwindEncoding ==
MOFI->getCompactUnwindDwarfEHFrameOnly();
Emitter.EmitCompactUnwind(Frame);
}
}
if (!NeedsEHFrameSection) return;
MCSection &Section =
IsEH ? *const_cast<MCObjectFileInfo *>(MOFI)->getEHFrameSection()
: *MOFI->getDwarfFrameSection();
Streamer.SwitchSection(&Section);
MCSymbol *SectionStart = Context.createTempSymbol();
Streamer.emitLabel(SectionStart);
DenseMap<CIEKey, const MCSymbol *> CIEStarts;
const MCSymbol *DummyDebugKey = nullptr;
bool CanOmitDwarf = MOFI->getOmitDwarfIfHaveCompactUnwind();
// Sort the FDEs by their corresponding CIE before we emit them.
// This isn't technically necessary according to the DWARF standard,
// but the Android libunwindstack rejects eh_frame sections where
// an FDE refers to a CIE other than the closest previous CIE.
std::vector<MCDwarfFrameInfo> FrameArrayX(FrameArray.begin(), FrameArray.end());
llvm::stable_sort(FrameArrayX,
[](const MCDwarfFrameInfo &X, const MCDwarfFrameInfo &Y) {
return CIEKey(X) < CIEKey(Y);
});
for (auto I = FrameArrayX.begin(), E = FrameArrayX.end(); I != E;) {
const MCDwarfFrameInfo &Frame = *I;
++I;
if (CanOmitDwarf && Frame.CompactUnwindEncoding !=
MOFI->getCompactUnwindDwarfEHFrameOnly())
// Don't generate an EH frame if we don't need one. I.e., it's taken care
// of by the compact unwind encoding.
continue;
CIEKey Key(Frame);
const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
if (!CIEStart)
CIEStart = &Emitter.EmitCIE(Frame);
Emitter.EmitFDE(*CIEStart, Frame, I == E, *SectionStart);
}
}
void MCDwarfFrameEmitter::EmitAdvanceLoc(MCObjectStreamer &Streamer,
uint64_t AddrDelta) {
MCContext &Context = Streamer.getContext();
SmallString<256> Tmp;
raw_svector_ostream OS(Tmp);
MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS);
Streamer.emitBytes(OS.str());
}
void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
uint64_t AddrDelta, raw_ostream &OS,
uint32_t *Offset, uint32_t *Size) {
// Scale the address delta by the minimum instruction length.
AddrDelta = ScaleAddrDelta(Context, AddrDelta);
bool WithFixups = false;
if (Offset && Size)
WithFixups = true;
support::endianness E =
Context.getAsmInfo()->isLittleEndian() ? support::little : support::big;
if (AddrDelta == 0) {
if (WithFixups) {
*Offset = 0;
*Size = 0;
}
} else if (isUIntN(6, AddrDelta)) {
uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
if (WithFixups) {
*Offset = OS.tell();
*Size = 6;
OS << uint8_t(dwarf::DW_CFA_advance_loc);
} else
OS << Opcode;
} else if (isUInt<8>(AddrDelta)) {
OS << uint8_t(dwarf::DW_CFA_advance_loc1);
if (WithFixups) {
*Offset = OS.tell();
*Size = 8;
OS.write_zeros(1);
} else
OS << uint8_t(AddrDelta);
} else if (isUInt<16>(AddrDelta)) {
OS << uint8_t(dwarf::DW_CFA_advance_loc2);
if (WithFixups) {
*Offset = OS.tell();
*Size = 16;
OS.write_zeros(2);
} else
support::endian::write<uint16_t>(OS, AddrDelta, E);
} else {
assert(isUInt<32>(AddrDelta));
OS << uint8_t(dwarf::DW_CFA_advance_loc4);
if (WithFixups) {
*Offset = OS.tell();
*Size = 32;
OS.write_zeros(4);
} else
support::endian::write<uint32_t>(OS, AddrDelta, E);
}
}
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