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llvm-6502/lib/MC/MCDwarf.cpp
Bill Wendling fa2b25c573 Relax this assert. It may not hold in all cases. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179814 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-18 23:16:46 +00:00

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//===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCDwarf.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Twine.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/MCObjectWriter.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
// Given a special op, return the address skip amount (in units of
// DWARF2_LINE_MIN_INSN_LENGTH.
#define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)
// The maximum address skip amount that can be encoded with a special op.
#define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255)
// First special line opcode - leave room for the standard opcodes.
// Note: If you want to change this, you'll have to update the
// "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit().
#define DWARF2_LINE_OPCODE_BASE 13
// Minimum line offset in a special line info. opcode. This value
// was chosen to give a reasonable range of values.
#define DWARF2_LINE_BASE -5
// Range of line offsets in a special line info. opcode.
#define DWARF2_LINE_RANGE 14
// Define the architecture-dependent minimum instruction length (in bytes).
// This value should be rather too small than too big.
#define DWARF2_LINE_MIN_INSN_LENGTH 1
// Note: when DWARF2_LINE_MIN_INSN_LENGTH == 1 which is the current setting,
// this routine is a nop and will be optimized away.
static inline uint64_t ScaleAddrDelta(uint64_t AddrDelta) {
if (DWARF2_LINE_MIN_INSN_LENGTH == 1)
return AddrDelta;
if (AddrDelta % DWARF2_LINE_MIN_INSN_LENGTH != 0) {
// TODO: report this error, but really only once.
;
}
return AddrDelta / DWARF2_LINE_MIN_INSN_LENGTH;
}
//
// 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 MCLineEntry::Make(MCStreamer *MCOS, const 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 MCLineEntry.
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.
MCLineEntry LineEntry(LineSym, DwarfLoc);
// clear DwarfLocSeen saying the current .loc info is now used.
MCOS->getContext().ClearDwarfLocSeen();
// Get the MCLineSection for this section, if one does not exist for this
// section create it.
const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
MCOS->getContext().getMCLineSections();
MCLineSection *LineSection = MCLineSections.lookup(Section);
if (!LineSection) {
// Create a new MCLineSection. This will be deleted after the dwarf line
// table is created using it by iterating through the MCLineSections
// DenseMap.
LineSection = new MCLineSection;
// Save a pointer to the new LineSection into the MCLineSections DenseMap.
MCOS->getContext().addMCLineSection(Section, LineSection);
}
// Add the line entry to this section's entries.
LineSection->addLineEntry(LineEntry,
MCOS->getContext().getDwarfCompileUnitID());
}
//
// This helper routine returns an expression of End - Start + IntVal .
//
static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
const MCSymbol &Start,
const MCSymbol &End,
int IntVal) {
MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
const MCExpr *Res =
MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext());
const MCExpr *RHS =
MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext());
const MCExpr *Res1 =
MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
const MCExpr *Res2 =
MCConstantExpr::Create(IntVal, MCOS.getContext());
const MCExpr *Res3 =
MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
return Res3;
}
//
// This emits the Dwarf line table for the specified section from the entries
// in the LineSection.
//
static inline void EmitDwarfLineTable(MCStreamer *MCOS,
const MCSection *Section,
const MCLineSection *LineSection,
unsigned CUID) {
// This LineSection does not contain any LineEntry for the given Compile Unit.
if (!LineSection->containEntriesForID(CUID))
return;
unsigned FileNum = 1;
unsigned LastLine = 1;
unsigned Column = 0;
unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
unsigned Isa = 0;
MCSymbol *LastLabel = NULL;
// Loop through each MCLineEntry and encode the dwarf line number table.
for (MCLineSection::const_iterator
it = LineSection->getMCLineEntries(CUID).begin(),
ie = LineSection->getMCLineEntries(CUID).end(); it != ie; ++it) {
if (FileNum != it->getFileNum()) {
FileNum = it->getFileNum();
MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
MCOS->EmitULEB128IntValue(FileNum);
}
if (Column != it->getColumn()) {
Column = it->getColumn();
MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
MCOS->EmitULEB128IntValue(Column);
}
if (Isa != it->getIsa()) {
Isa = it->getIsa();
MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
MCOS->EmitULEB128IntValue(Isa);
}
if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
Flags = it->getFlags();
MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
}
if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK)
MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END)
MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);
int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine;
MCSymbol *Label = it->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.getPointerSize());
LastLine = it->getLine();
LastLabel = Label;
}
// Emit a DW_LNE_end_sequence for the end of the section.
// Using the pointer Section create a temporary label at the end of the
// section and use that and the LastLabel to compute the address delta
// and use INT64_MAX as the line delta which is the signal that this is
// actually a DW_LNE_end_sequence.
// Switch to the section to be able to create a symbol at its end.
// TODO: keep track of the last subsection so that this symbol appears in the
// correct place.
MCOS->SwitchSection(Section);
MCContext &context = MCOS->getContext();
// Create a symbol at the end of the section.
MCSymbol *SectionEnd = context.CreateTempSymbol();
// Set the value of the symbol, as we are at the end of the section.
MCOS->EmitLabel(SectionEnd);
// Switch back the dwarf line section.
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
const MCAsmInfo &asmInfo = MCOS->getContext().getAsmInfo();
MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd,
asmInfo.getPointerSize());
}
//
// This emits the Dwarf file and the line tables.
//
const MCSymbol *MCDwarfFileTable::Emit(MCStreamer *MCOS) {
MCContext &context = MCOS->getContext();
// Switch to the section where the table will be emitted into.
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
const DenseMap<unsigned, MCSymbol *> &MCLineTableSymbols =
MCOS->getContext().getMCLineTableSymbols();
// CUID and MCLineTableSymbols are set in DwarfDebug, when DwarfDebug does
// not exist, CUID will be 0 and MCLineTableSymbols will be empty.
// Handle Compile Unit 0, the line table start symbol is the section symbol.
const MCSymbol *LineStartSym = EmitCU(MCOS, 0);
// Handle the rest of the Compile Units.
for (unsigned Is = 1, Ie = MCLineTableSymbols.size(); Is < Ie; Is++)
EmitCU(MCOS, Is);
// Now delete the MCLineSections that were created in MCLineEntry::Make()
// and used to emit the line table.
const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
MCOS->getContext().getMCLineSections();
for (DenseMap<const MCSection *, MCLineSection *>::const_iterator it =
MCLineSections.begin(), ie = MCLineSections.end(); it != ie;
++it)
delete it->second;
return LineStartSym;
}
const MCSymbol *MCDwarfFileTable::EmitCU(MCStreamer *MCOS, unsigned CUID) {
MCContext &context = MCOS->getContext();
// Create a symbol at the beginning of the line table.
MCSymbol *LineStartSym = MCOS->getContext().getMCLineTableSymbol(CUID);
if (!LineStartSym)
LineStartSym = context.CreateTempSymbol();
// Set the value of the symbol, as we are at the start of the line table.
MCOS->EmitLabel(LineStartSym);
// Create a symbol for the end of the section (to be set when we get there).
MCSymbol *LineEndSym = context.CreateTempSymbol();
// The first 4 bytes is the total length of the information for this
// compilation unit (not including these 4 bytes for the length).
MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4),
4);
// Next 2 bytes is the Version, which is Dwarf 2.
MCOS->EmitIntValue(2, 2);
// Create a symbol for the end of the prologue (to be set when we get there).
MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end
// Length of the prologue, is the next 4 bytes. Which is the start of the
// section to the end of the prologue. Not including the 4 bytes for the
// total length, the 2 bytes for the version, and these 4 bytes for the
// length of the prologue.
MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
(4 + 2 + 4)), 4, 0);
// Parameters of the state machine, are next.
MCOS->EmitIntValue(DWARF2_LINE_MIN_INSN_LENGTH, 1);
MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1);
// Standard opcode lengths
MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy
MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc
MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line
MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file
MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column
MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa
// Put out the directory and file tables.
// First the directory table.
const SmallVectorImpl<StringRef> &MCDwarfDirs =
context.getMCDwarfDirs(CUID);
for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
MCOS->EmitBytes(MCDwarfDirs[i]); // the DirectoryName
MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
}
MCOS->EmitIntValue(0, 1); // Terminate the directory list
// Second the file table.
const SmallVectorImpl<MCDwarfFile *> &MCDwarfFiles =
MCOS->getContext().getMCDwarfFiles(CUID);
for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
MCOS->EmitBytes(MCDwarfFiles[i]->getName()); // FileName
MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
// the Directory num
MCOS->EmitULEB128IntValue(MCDwarfFiles[i]->getDirIndex());
MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
MCOS->EmitIntValue(0, 1); // filesize (always 0)
}
MCOS->EmitIntValue(0, 1); // Terminate the file list
// 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);
// Put out the line tables.
const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
MCOS->getContext().getMCLineSections();
const std::vector<const MCSection *> &MCLineSectionOrder =
MCOS->getContext().getMCLineSectionOrder();
for (std::vector<const MCSection*>::const_iterator it =
MCLineSectionOrder.begin(), ie = MCLineSectionOrder.end(); it != ie;
++it) {
const MCSection *Sec = *it;
const MCLineSection *Line = MCLineSections.lookup(Sec);
EmitDwarfLineTable(MCOS, Sec, Line, CUID);
}
if (MCOS->getContext().getAsmInfo().getLinkerRequiresNonEmptyDwarfLines()
&& MCLineSectionOrder.begin() == MCLineSectionOrder.end()) {
// The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
// it requires:
// total_length >= prologue_length + 10
// We are 4 bytes short, since we have total_length = 51 and
// prologue_length = 45
// The regular end_sequence should be sufficient.
MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
}
// 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);
return LineStartSym;
}
/// Utility function to write the encoding to an object writer.
void MCDwarfLineAddr::Write(MCObjectWriter *OW, int64_t LineDelta,
uint64_t AddrDelta) {
SmallString<256> Tmp;
raw_svector_ostream OS(Tmp);
MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
OW->WriteBytes(OS.str());
}
/// Utility function to emit the encoding to a streamer.
void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
uint64_t AddrDelta) {
SmallString<256> Tmp;
raw_svector_ostream OS(Tmp);
MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
MCOS->EmitBytes(OS.str());
}
/// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
void MCDwarfLineAddr::Encode(int64_t LineDelta, uint64_t AddrDelta,
raw_ostream &OS) {
uint64_t Temp, Opcode;
bool NeedCopy = false;
// Scale the address delta by the minimum instruction length.
AddrDelta = ScaleAddrDelta(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 == MAX_SPECIAL_ADDR_DELTA)
OS << char(dwarf::DW_LNS_const_add_pc);
else {
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 - DWARF2_LINE_BASE;
// If the line increment is out of range of a special opcode, we must encode
// it with DW_LNS_advance_line.
if (Temp >= DWARF2_LINE_RANGE) {
OS << char(dwarf::DW_LNS_advance_line);
encodeSLEB128(LineDelta, OS);
LineDelta = 0;
Temp = 0 - DWARF2_LINE_BASE;
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 += DWARF2_LINE_OPCODE_BASE;
// Avoid overflow when addr_delta is large.
if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
// Try using a special opcode.
Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
if (Opcode <= 255) {
OS << char(Opcode);
return;
}
// Try using DW_LNS_const_add_pc followed by special op.
Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
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
OS << char(Temp);
}
void MCDwarfFile::print(raw_ostream &OS) const {
OS << '"' << getName() << '"';
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void MCDwarfFile::dump() const {
print(dbgs());
}
#endif
// Utility function to write a tuple for .debug_abbrev.
static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) {
MCOS->EmitULEB128IntValue(Name);
MCOS->EmitULEB128IntValue(Form);
}
// When generating dwarf for assembly source files this emits
// the data for .debug_abbrev section which contains three DIEs.
static void EmitGenDwarfAbbrev(MCStreamer *MCOS) {
MCContext &context = MCOS->getContext();
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection());
// DW_TAG_compile_unit DIE abbrev (1).
MCOS->EmitULEB128IntValue(1);
MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit);
MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4);
EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr);
EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string);
StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
if (!DwarfDebugFlags.empty())
EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string);
EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string);
EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2);
EmitAbbrev(MCOS, 0, 0);
// DW_TAG_label DIE abbrev (2).
MCOS->EmitULEB128IntValue(2);
MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label);
MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1);
EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string);
EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4);
EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4);
EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr);
EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag);
EmitAbbrev(MCOS, 0, 0);
// DW_TAG_unspecified_parameters DIE abbrev (3).
MCOS->EmitULEB128IntValue(3);
MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters);
MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1);
EmitAbbrev(MCOS, 0, 0);
// Terminate the abbreviations for this compilation unit.
MCOS->EmitIntValue(0, 1);
}
// When generating dwarf for assembly source files this emits the data for
// .debug_aranges section. Which contains a header and a table of pairs of
// PointerSize'ed values for the address and size of section(s) with line table
// entries (just the default .text in our case) and a terminating pair of zeros.
static void EmitGenDwarfAranges(MCStreamer *MCOS,
const MCSymbol *InfoSectionSymbol) {
MCContext &context = MCOS->getContext();
// Create a symbol at the end of the section that we are creating the dwarf
// debugging info to use later in here as part of the expression to calculate
// the size of the section for the table.
MCOS->SwitchSection(context.getGenDwarfSection());
MCSymbol *SectionEndSym = context.CreateTempSymbol();
MCOS->EmitLabel(SectionEndSym);
context.setGenDwarfSectionEndSym(SectionEndSym);
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection());
// This will be the length of the .debug_aranges section, first account for
// the size of each item in the header (see below where we emit these items).
int Length = 4 + 2 + 4 + 1 + 1;
// Figure the padding after the header before the table of address and size
// pairs who's values are PointerSize'ed.
const MCAsmInfo &asmInfo = context.getAsmInfo();
int AddrSize = asmInfo.getPointerSize();
int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1));
if (Pad == 2 * AddrSize)
Pad = 0;
Length += Pad;
// Add the size of the pair of PointerSize'ed values for the address and size
// of the one default .text section we have in the table.
Length += 2 * AddrSize;
// And the pair of terminating zeros.
Length += 2 * AddrSize;
// Emit the header for this section.
// The 4 byte length not including the 4 byte value for the length.
MCOS->EmitIntValue(Length - 4, 4);
// The 2 byte version, which is 2.
MCOS->EmitIntValue(2, 2);
// The 4 byte offset to the compile unit in the .debug_info from the start
// of the .debug_info.
if (InfoSectionSymbol)
MCOS->EmitSymbolValue(InfoSectionSymbol, 4);
else
MCOS->EmitIntValue(0, 4);
// The 1 byte size of an address.
MCOS->EmitIntValue(AddrSize, 1);
// The 1 byte size of a segment descriptor, we use a value of zero.
MCOS->EmitIntValue(0, 1);
// Align the header with the padding if needed, before we put out the table.
for(int i = 0; i < Pad; i++)
MCOS->EmitIntValue(0, 1);
// Now emit the table of pairs of PointerSize'ed values for the section(s)
// address and size, in our case just the one default .text section.
const MCExpr *Addr = MCSymbolRefExpr::Create(
context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
const MCExpr *Size = MakeStartMinusEndExpr(*MCOS,
*context.getGenDwarfSectionStartSym(), *SectionEndSym, 0);
MCOS->EmitAbsValue(Addr, AddrSize);
MCOS->EmitAbsValue(Size, AddrSize);
// And finally the pair of terminating zeros.
MCOS->EmitIntValue(0, AddrSize);
MCOS->EmitIntValue(0, AddrSize);
}
// When generating dwarf for assembly source files this emits the data for
// .debug_info section which contains three parts. The header, the compile_unit
// DIE and a list of label DIEs.
static void EmitGenDwarfInfo(MCStreamer *MCOS,
const MCSymbol *AbbrevSectionSymbol,
const MCSymbol *LineSectionSymbol) {
MCContext &context = MCOS->getContext();
MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection());
// Create a symbol at the start and end of this section used in here for the
// expression to calculate the length in the header.
MCSymbol *InfoStart = context.CreateTempSymbol();
MCOS->EmitLabel(InfoStart);
MCSymbol *InfoEnd = context.CreateTempSymbol();
// First part: the header.
// The 4 byte total length of the information for this compilation unit, not
// including these 4 bytes.
const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4);
MCOS->EmitAbsValue(Length, 4);
// The 2 byte DWARF version, which is 2.
MCOS->EmitIntValue(2, 2);
// The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev,
// it is at the start of that section so this is zero.
if (AbbrevSectionSymbol) {
MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4);
} else {
MCOS->EmitIntValue(0, 4);
}
const MCAsmInfo &asmInfo = context.getAsmInfo();
int AddrSize = asmInfo.getPointerSize();
// The 1 byte size of an address.
MCOS->EmitIntValue(AddrSize, 1);
// Second part: the compile_unit DIE.
// The DW_TAG_compile_unit DIE abbrev (1).
MCOS->EmitULEB128IntValue(1);
// DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section,
// which is at the start of that section so this is zero.
if (LineSectionSymbol) {
MCOS->EmitSymbolValue(LineSectionSymbol, 4);
} else {
MCOS->EmitIntValue(0, 4);
}
// AT_low_pc, the first address of the default .text section.
const MCExpr *Start = MCSymbolRefExpr::Create(
context.getGenDwarfSectionStartSym(), MCSymbolRefExpr::VK_None, context);
MCOS->EmitAbsValue(Start, AddrSize);
// AT_high_pc, the last address of the default .text section.
const MCExpr *End = MCSymbolRefExpr::Create(
context.getGenDwarfSectionEndSym(), MCSymbolRefExpr::VK_None, context);
MCOS->EmitAbsValue(End, AddrSize);
// AT_name, the name of the source file. Reconstruct from the first directory
// and file table entries.
const SmallVectorImpl<StringRef> &MCDwarfDirs =
context.getMCDwarfDirs();
if (MCDwarfDirs.size() > 0) {
MCOS->EmitBytes(MCDwarfDirs[0]);
MCOS->EmitBytes("/");
}
const SmallVectorImpl<MCDwarfFile *> &MCDwarfFiles =
MCOS->getContext().getMCDwarfFiles();
MCOS->EmitBytes(MCDwarfFiles[1]->getName());
MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
// AT_comp_dir, the working directory the assembly was done in.
MCOS->EmitBytes(context.getCompilationDir());
MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
// AT_APPLE_flags, the command line arguments of the assembler tool.
StringRef DwarfDebugFlags = context.getDwarfDebugFlags();
if (!DwarfDebugFlags.empty()){
MCOS->EmitBytes(DwarfDebugFlags);
MCOS->EmitIntValue(0, 1); // 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 "));
MCOS->EmitBytes(StringRef(PACKAGE_VERSION));
MCOS->EmitBytes(StringRef(")"));
}
MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
// AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2
// draft has no standard code for assembler.
MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2);
// Third part: the list of label DIEs.
// Loop on saved info for dwarf labels and create the DIEs for them.
const std::vector<const MCGenDwarfLabelEntry *> &Entries =
MCOS->getContext().getMCGenDwarfLabelEntries();
for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
Entries.begin(), ie = Entries.end(); it != ie;
++it) {
const MCGenDwarfLabelEntry *Entry = *it;
// The DW_TAG_label DIE abbrev (2).
MCOS->EmitULEB128IntValue(2);
// AT_name, of the label without any leading underbar.
MCOS->EmitBytes(Entry->getName());
MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string.
// AT_decl_file, index into the file table.
MCOS->EmitIntValue(Entry->getFileNumber(), 4);
// AT_decl_line, source line number.
MCOS->EmitIntValue(Entry->getLineNumber(), 4);
// AT_low_pc, start address of the label.
const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry->getLabel(),
MCSymbolRefExpr::VK_None, context);
MCOS->EmitAbsValue(AT_low_pc, AddrSize);
// DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype.
MCOS->EmitIntValue(0, 1);
// The DW_TAG_unspecified_parameters DIE abbrev (3).
MCOS->EmitULEB128IntValue(3);
// Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's.
MCOS->EmitIntValue(0, 1);
}
// Deallocate the MCGenDwarfLabelEntry classes that saved away the info
// for the dwarf labels.
for (std::vector<const MCGenDwarfLabelEntry *>::const_iterator it =
Entries.begin(), ie = Entries.end(); it != ie;
++it) {
const MCGenDwarfLabelEntry *Entry = *it;
delete Entry;
}
// Add the NULL DIE terminating the Compile Unit DIE's.
MCOS->EmitIntValue(0, 1);
// Now set the value of the symbol at the end of the info section.
MCOS->EmitLabel(InfoEnd);
}
//
// When generating dwarf for assembly source files this emits the Dwarf
// sections.
//
void MCGenDwarfInfo::Emit(MCStreamer *MCOS, const MCSymbol *LineSectionSymbol) {
// Create the dwarf sections in this order (.debug_line already created).
MCContext &context = MCOS->getContext();
const MCAsmInfo &AsmInfo = context.getAsmInfo();
bool CreateDwarfSectionSymbols =
AsmInfo.doesDwarfUseRelocationsAcrossSections();
if (!CreateDwarfSectionSymbols)
LineSectionSymbol = NULL;
MCSymbol *AbbrevSectionSymbol = NULL;
MCSymbol *InfoSectionSymbol = NULL;
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());
// If there are no line table entries then do not emit any section contents.
if (context.getMCLineSections().empty())
return;
// Output the data for .debug_aranges section.
EmitGenDwarfAranges(MCOS, InfoSectionSymbol);
// Output the data for .debug_abbrev section.
EmitGenDwarfAbbrev(MCOS);
// Output the data for .debug_info section.
EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol);
}
//
// 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 or symbols not in
// the default text.
if (Symbol->isTemporary())
return;
MCContext &context = MCOS->getContext();
if (context.getGenDwarfSection() != MCOS->getCurrentSection().first)
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.
int CurBuffer = SrcMgr.FindBufferContainingLoc(Loc);
unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer);
// We create a temporary symbol for use for the AT_high_pc and AT_low_pc
// values so that they don't have things like an ARM thumb bit from the
// original symbol. So when used they won't get a low bit set after
// relocation.
MCSymbol *Label = context.CreateTempSymbol();
MCOS->EmitLabel(Label);
// Create and entry for the info and add it to the other entries.
MCGenDwarfLabelEntry *Entry =
new MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label);
MCOS->getContext().addMCGenDwarfLabelEntry(Entry);
}
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().getPointerSize();
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 EmitSymbol(MCStreamer &streamer, const MCSymbol &symbol,
unsigned symbolEncoding, const char *comment = 0) {
MCContext &context = streamer.getContext();
const MCAsmInfo &asmInfo = context.getAsmInfo();
const MCExpr *v = asmInfo.getExprForFDESymbol(&symbol,
symbolEncoding,
streamer);
unsigned size = getSizeForEncoding(streamer, symbolEncoding);
if (streamer.isVerboseAsm() && comment) streamer.AddComment(comment);
streamer.EmitAbsValue(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);
}
static const MachineLocation TranslateMachineLocation(
const MCRegisterInfo &MRI,
const MachineLocation &Loc) {
unsigned Reg = Loc.getReg() == MachineLocation::VirtualFP ?
MachineLocation::VirtualFP :
unsigned(MRI.getDwarfRegNum(Loc.getReg(), true));
const MachineLocation &NewLoc = Loc.isReg() ?
MachineLocation(Reg) : MachineLocation(Reg, Loc.getOffset());
return NewLoc;
}
namespace {
class FrameEmitterImpl {
int CFAOffset;
int CIENum;
bool UsingCFI;
bool IsEH;
const MCSymbol *SectionStart;
public:
FrameEmitterImpl(bool usingCFI, bool isEH)
: CFAOffset(0), CIENum(0), UsingCFI(usingCFI), IsEH(isEH),
SectionStart(0) {}
void setSectionStart(const MCSymbol *Label) { SectionStart = Label; }
/// EmitCompactUnwind - Emit the unwind information in a compact way. If
/// we're successful, return 'true'. Otherwise, return 'false' and it will
/// emit the normal CIE and FDE.
void EmitCompactUnwind(MCStreamer &streamer,
const MCDwarfFrameInfo &frame);
const MCSymbol &EmitCIE(MCStreamer &streamer,
const MCSymbol *personality,
unsigned personalityEncoding,
const MCSymbol *lsda,
bool IsSignalFrame,
unsigned lsdaEncoding);
MCSymbol *EmitFDE(MCStreamer &streamer,
const MCSymbol &cieStart,
const MCDwarfFrameInfo &frame);
void EmitCFIInstructions(MCStreamer &streamer,
const std::vector<MCCFIInstruction> &Instrs,
MCSymbol *BaseLabel);
void EmitCFIInstruction(MCStreamer &Streamer,
const MCCFIInstruction &Instr);
};
} // end anonymous namespace
static void EmitEncodingByte(MCStreamer &Streamer, unsigned Encoding,
StringRef Prefix) {
if (Streamer.isVerboseAsm()) {
const char *EncStr;
switch (Encoding) {
default: EncStr = "<unknown encoding>"; break;
case dwarf::DW_EH_PE_absptr: EncStr = "absptr"; break;
case dwarf::DW_EH_PE_omit: EncStr = "omit"; break;
case dwarf::DW_EH_PE_pcrel: EncStr = "pcrel"; break;
case dwarf::DW_EH_PE_udata4: EncStr = "udata4"; break;
case dwarf::DW_EH_PE_udata8: EncStr = "udata8"; break;
case dwarf::DW_EH_PE_sdata4: EncStr = "sdata4"; break;
case dwarf::DW_EH_PE_sdata8: EncStr = "sdata8"; break;
case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
EncStr = "pcrel udata4";
break;
case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
EncStr = "pcrel sdata4";
break;
case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
EncStr = "pcrel udata8";
break;
case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
EncStr = "screl sdata8";
break;
case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata4:
EncStr = "indirect pcrel udata4";
break;
case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata4:
EncStr = "indirect pcrel sdata4";
break;
case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_udata8:
EncStr = "indirect pcrel udata8";
break;
case dwarf::DW_EH_PE_indirect |dwarf::DW_EH_PE_pcrel|dwarf::DW_EH_PE_sdata8:
EncStr = "indirect pcrel sdata8";
break;
}
Streamer.AddComment(Twine(Prefix) + " = " + EncStr);
}
Streamer.EmitIntValue(Encoding, 1);
}
void FrameEmitterImpl::EmitCFIInstruction(MCStreamer &Streamer,
const MCCFIInstruction &Instr) {
int dataAlignmentFactor = getDataAlignmentFactor(Streamer);
bool VerboseAsm = Streamer.isVerboseAsm();
switch (Instr.getOperation()) {
case MCCFIInstruction::OpRegister: {
unsigned Reg1 = Instr.getRegister();
unsigned Reg2 = Instr.getRegister2();
if (VerboseAsm) {
Streamer.AddComment("DW_CFA_register");
Streamer.AddComment(Twine("Reg1 ") + Twine(Reg1));
Streamer.AddComment(Twine("Reg2 ") + Twine(Reg2));
}
Streamer.EmitIntValue(dwarf::DW_CFA_register, 1);
Streamer.EmitULEB128IntValue(Reg1);
Streamer.EmitULEB128IntValue(Reg2);
return;
}
case MCCFIInstruction::OpUndefined: {
unsigned Reg = Instr.getRegister();
if (VerboseAsm) {
Streamer.AddComment("DW_CFA_undefined");
Streamer.AddComment(Twine("Reg ") + Twine(Reg));
}
Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);
Streamer.EmitULEB128IntValue(Reg);
return;
}
case MCCFIInstruction::OpAdjustCfaOffset:
case MCCFIInstruction::OpDefCfaOffset: {
const bool IsRelative =
Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset;
if (VerboseAsm)
Streamer.AddComment("DW_CFA_def_cfa_offset");
Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
if (IsRelative)
CFAOffset += Instr.getOffset();
else
CFAOffset = -Instr.getOffset();
if (VerboseAsm)
Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
Streamer.EmitULEB128IntValue(CFAOffset);
return;
}
case MCCFIInstruction::OpDefCfa: {
if (VerboseAsm)
Streamer.AddComment("DW_CFA_def_cfa");
Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
if (VerboseAsm)
Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
Streamer.EmitULEB128IntValue(Instr.getRegister());
CFAOffset = -Instr.getOffset();
if (VerboseAsm)
Streamer.AddComment(Twine("Offset " + Twine(CFAOffset)));
Streamer.EmitULEB128IntValue(CFAOffset);
return;
}
case MCCFIInstruction::OpDefCfaRegister: {
if (VerboseAsm)
Streamer.AddComment("DW_CFA_def_cfa_register");
Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
if (VerboseAsm)
Streamer.AddComment(Twine("Reg ") + Twine(Instr.getRegister()));
Streamer.EmitULEB128IntValue(Instr.getRegister());
return;
}
case MCCFIInstruction::OpOffset:
case MCCFIInstruction::OpRelOffset: {
const bool IsRelative =
Instr.getOperation() == MCCFIInstruction::OpRelOffset;
unsigned Reg = Instr.getRegister();
int Offset = Instr.getOffset();
if (IsRelative)
Offset -= CFAOffset;
Offset = Offset / dataAlignmentFactor;
if (Offset < 0) {
if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended_sf");
Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
Streamer.EmitULEB128IntValue(Reg);
if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
Streamer.EmitSLEB128IntValue(Offset);
} else if (Reg < 64) {
if (VerboseAsm) Streamer.AddComment(Twine("DW_CFA_offset + Reg(") +
Twine(Reg) + ")");
Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
Streamer.EmitULEB128IntValue(Offset);
} else {
if (VerboseAsm) Streamer.AddComment("DW_CFA_offset_extended");
Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
Streamer.EmitULEB128IntValue(Reg);
if (VerboseAsm) Streamer.AddComment(Twine("Offset ") + Twine(Offset));
Streamer.EmitULEB128IntValue(Offset);
}
return;
}
case MCCFIInstruction::OpRememberState:
if (VerboseAsm) Streamer.AddComment("DW_CFA_remember_state");
Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1);
return;
case MCCFIInstruction::OpRestoreState:
if (VerboseAsm) Streamer.AddComment("DW_CFA_restore_state");
Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1);
return;
case MCCFIInstruction::OpSameValue: {
unsigned Reg = Instr.getRegister();
if (VerboseAsm) Streamer.AddComment("DW_CFA_same_value");
Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1);
if (VerboseAsm) Streamer.AddComment(Twine("Reg ") + Twine(Reg));
Streamer.EmitULEB128IntValue(Reg);
return;
}
case MCCFIInstruction::OpRestore: {
unsigned Reg = Instr.getRegister();
if (VerboseAsm) {
Streamer.AddComment("DW_CFA_restore");
Streamer.AddComment(Twine("Reg ") + Twine(Reg));
}
Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
return;
}
case MCCFIInstruction::OpEscape:
if (VerboseAsm) Streamer.AddComment("Escape bytes");
Streamer.EmitBytes(Instr.getValues());
return;
}
llvm_unreachable("Unhandled case in switch");
}
/// EmitFrameMoves - Emit frame instructions to describe the layout of the
/// frame.
void FrameEmitterImpl::EmitCFIInstructions(MCStreamer &streamer,
const std::vector<MCCFIInstruction> &Instrs,
MCSymbol *BaseLabel) {
for (unsigned i = 0, N = Instrs.size(); i < N; ++i) {
const MCCFIInstruction &Instr = Instrs[i];
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) {
if (streamer.isVerboseAsm()) streamer.AddComment("DW_CFA_advance_loc4");
streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym);
BaseLabel = ThisSym;
}
}
EmitCFIInstruction(streamer, Instr);
}
}
/// EmitCompactUnwind - Emit the unwind information in a compact way. If we're
/// successful, return 'true'. Otherwise, return 'false' and it will emit the
/// normal CIE and FDE.
void FrameEmitterImpl::EmitCompactUnwind(MCStreamer &Streamer,
const MCDwarfFrameInfo &Frame) {
MCContext &Context = Streamer.getContext();
const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
bool VerboseAsm = Streamer.isVerboseAsm();
// 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;
Streamer.SwitchSection(MOFI->getCompactUnwindSection());
// Range Start
unsigned FDEEncoding = MOFI->getFDEEncoding(UsingCFI);
unsigned Size = getSizeForEncoding(Streamer, FDEEncoding);
if (VerboseAsm) Streamer.AddComment("Range Start");
Streamer.EmitSymbolValue(Frame.Function, Size);
// Range Length
const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin,
*Frame.End, 0);
if (VerboseAsm) Streamer.AddComment("Range Length");
Streamer.EmitAbsValue(Range, 4);
// Compact Encoding
Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4);
if (VerboseAsm) Streamer.AddComment("Compact Unwind Encoding: 0x" +
Twine::utohexstr(Encoding));
Streamer.EmitIntValue(Encoding, Size);
// Personality Function
Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr);
if (VerboseAsm) Streamer.AddComment("Personality Function");
if (!DwarfEHFrameOnly && Frame.Personality)
Streamer.EmitSymbolValue(Frame.Personality, Size);
else
Streamer.EmitIntValue(0, Size); // No personality fn
// LSDA
Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding);
if (VerboseAsm) Streamer.AddComment("LSDA");
if (!DwarfEHFrameOnly && Frame.Lsda)
Streamer.EmitSymbolValue(Frame.Lsda, Size);
else
Streamer.EmitIntValue(0, Size); // No LSDA
}
const MCSymbol &FrameEmitterImpl::EmitCIE(MCStreamer &streamer,
const MCSymbol *personality,
unsigned personalityEncoding,
const MCSymbol *lsda,
bool IsSignalFrame,
unsigned lsdaEncoding) {
MCContext &context = streamer.getContext();
const MCRegisterInfo &MRI = context.getRegisterInfo();
const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
bool verboseAsm = streamer.isVerboseAsm();
MCSymbol *sectionStart;
if (MOFI->isFunctionEHFrameSymbolPrivate() || !IsEH)
sectionStart = context.CreateTempSymbol();
else
sectionStart = context.GetOrCreateSymbol(Twine("EH_frame") + Twine(CIENum));
streamer.EmitLabel(sectionStart);
CIENum++;
MCSymbol *sectionEnd = context.CreateTempSymbol();
// Length
const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
*sectionEnd, 4);
if (verboseAsm) streamer.AddComment("CIE Length");
streamer.EmitAbsValue(Length, 4);
// CIE ID
unsigned CIE_ID = IsEH ? 0 : -1;
if (verboseAsm) streamer.AddComment("CIE ID Tag");
streamer.EmitIntValue(CIE_ID, 4);
// Version
if (verboseAsm) streamer.AddComment("DW_CIE_VERSION");
streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);
// Augmentation String
SmallString<8> Augmentation;
if (IsEH) {
if (verboseAsm) streamer.AddComment("CIE Augmentation");
Augmentation += "z";
if (personality)
Augmentation += "P";
if (lsda)
Augmentation += "L";
Augmentation += "R";
if (IsSignalFrame)
Augmentation += "S";
streamer.EmitBytes(Augmentation.str());
}
streamer.EmitIntValue(0, 1);
// Code Alignment Factor
if (verboseAsm) streamer.AddComment("CIE Code Alignment Factor");
streamer.EmitULEB128IntValue(1);
// Data Alignment Factor
if (verboseAsm) streamer.AddComment("CIE Data Alignment Factor");
streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));
// Return Address Register
if (verboseAsm) streamer.AddComment("CIE Return Address Column");
streamer.EmitULEB128IntValue(MRI.getDwarfRegNum(MRI.getRARegister(), true));
// Augmentation Data Length (optional)
unsigned augmentationLength = 0;
if (IsEH) {
if (personality) {
// Personality Encoding
augmentationLength += 1;
// Personality
augmentationLength += getSizeForEncoding(streamer, personalityEncoding);
}
if (lsda)
augmentationLength += 1;
// Encoding of the FDE pointers
augmentationLength += 1;
if (verboseAsm) streamer.AddComment("Augmentation Size");
streamer.EmitULEB128IntValue(augmentationLength);
// Augmentation Data (optional)
if (personality) {
// Personality Encoding
EmitEncodingByte(streamer, personalityEncoding,
"Personality Encoding");
// Personality
if (verboseAsm) streamer.AddComment("Personality");
EmitPersonality(streamer, *personality, personalityEncoding);
}
if (lsda)
EmitEncodingByte(streamer, lsdaEncoding, "LSDA Encoding");
// Encoding of the FDE pointers
EmitEncodingByte(streamer, MOFI->getFDEEncoding(UsingCFI),
"FDE Encoding");
}
// Initial Instructions
const MCAsmInfo &MAI = context.getAsmInfo();
const std::vector<MachineMove> &Moves = MAI.getInitialFrameState();
std::vector<MCCFIInstruction> Instructions;
for (int i = 0, n = Moves.size(); i != n; ++i) {
MCSymbol *Label = Moves[i].getLabel();
const MachineLocation &Dst =
TranslateMachineLocation(MRI, Moves[i].getDestination());
const MachineLocation &Src =
TranslateMachineLocation(MRI, Moves[i].getSource());
if (Dst.isReg()) {
assert(Dst.getReg() == MachineLocation::VirtualFP);
assert(!Src.isReg());
MCCFIInstruction Inst =
MCCFIInstruction::createDefCfa(Label, Src.getReg(), -Src.getOffset());
Instructions.push_back(Inst);
} else {
assert(Src.isReg());
unsigned Reg = Src.getReg();
int Offset = Dst.getOffset();
MCCFIInstruction Inst =
MCCFIInstruction::createOffset(Label, Reg, Offset);
Instructions.push_back(Inst);
}
}
EmitCFIInstructions(streamer, Instructions, NULL);
// Padding
streamer.EmitValueToAlignment(IsEH
? 4 : context.getAsmInfo().getPointerSize());
streamer.EmitLabel(sectionEnd);
return *sectionStart;
}
MCSymbol *FrameEmitterImpl::EmitFDE(MCStreamer &streamer,
const MCSymbol &cieStart,
const MCDwarfFrameInfo &frame) {
MCContext &context = streamer.getContext();
MCSymbol *fdeStart = context.CreateTempSymbol();
MCSymbol *fdeEnd = context.CreateTempSymbol();
const MCObjectFileInfo *MOFI = context.getObjectFileInfo();
bool verboseAsm = streamer.isVerboseAsm();
if (IsEH && frame.Function && !MOFI->isFunctionEHFrameSymbolPrivate()) {
MCSymbol *EHSym =
context.GetOrCreateSymbol(frame.Function->getName() + Twine(".eh"));
streamer.EmitEHSymAttributes(frame.Function, EHSym);
streamer.EmitLabel(EHSym);
}
// Length
const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
if (verboseAsm) streamer.AddComment("FDE Length");
streamer.EmitAbsValue(Length, 4);
streamer.EmitLabel(fdeStart);
// CIE Pointer
const MCAsmInfo &asmInfo = context.getAsmInfo();
if (IsEH) {
const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
0);
if (verboseAsm) streamer.AddComment("FDE CIE Offset");
streamer.EmitAbsValue(offset, 4);
} else if (!asmInfo.doesDwarfUseRelocationsAcrossSections()) {
const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart,
cieStart, 0);
streamer.EmitAbsValue(offset, 4);
} else {
streamer.EmitSymbolValue(&cieStart, 4);
}
// PC Begin
unsigned PCEncoding = IsEH ? MOFI->getFDEEncoding(UsingCFI)
: (unsigned)dwarf::DW_EH_PE_absptr;
unsigned PCSize = getSizeForEncoding(streamer, PCEncoding);
EmitSymbol(streamer, *frame.Begin, PCEncoding, "FDE initial location");
// PC Range
const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
*frame.End, 0);
if (verboseAsm) streamer.AddComment("FDE address range");
streamer.EmitAbsValue(Range, PCSize);
if (IsEH) {
// Augmentation Data Length
unsigned augmentationLength = 0;
if (frame.Lsda)
augmentationLength += getSizeForEncoding(streamer, frame.LsdaEncoding);
if (verboseAsm) streamer.AddComment("Augmentation size");
streamer.EmitULEB128IntValue(augmentationLength);
// Augmentation Data
if (frame.Lsda)
EmitSymbol(streamer, *frame.Lsda, frame.LsdaEncoding,
"Language Specific Data Area");
}
// Call Frame Instructions
EmitCFIInstructions(streamer, frame.Instructions, frame.Begin);
// Padding
streamer.EmitValueToAlignment(PCSize);
return fdeEnd;
}
namespace {
struct CIEKey {
static const CIEKey getEmptyKey() { return CIEKey(0, 0, -1, false); }
static const CIEKey getTombstoneKey() { return CIEKey(0, -1, 0, false); }
CIEKey(const MCSymbol* Personality_, unsigned PersonalityEncoding_,
unsigned LsdaEncoding_, bool IsSignalFrame_) :
Personality(Personality_), PersonalityEncoding(PersonalityEncoding_),
LsdaEncoding(LsdaEncoding_), IsSignalFrame(IsSignalFrame_) {
}
const MCSymbol* Personality;
unsigned PersonalityEncoding;
unsigned LsdaEncoding;
bool IsSignalFrame;
};
}
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));
}
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;
}
};
}
void MCDwarfFrameEmitter::Emit(MCStreamer &Streamer,
bool UsingCFI,
bool IsEH) {
MCContext &Context = Streamer.getContext();
MCObjectFileInfo *MOFI =
const_cast<MCObjectFileInfo*>(Context.getObjectFileInfo());
FrameEmitterImpl Emitter(UsingCFI, IsEH);
ArrayRef<MCDwarfFrameInfo> FrameArray = Streamer.getFrameInfos();
// Emit the compact unwind info if available.
if (IsEH && MOFI->getCompactUnwindSection())
for (unsigned i = 0, n = Streamer.getNumFrameInfos(); i < n; ++i) {
const MCDwarfFrameInfo &Frame = Streamer.getFrameInfo(i);
Emitter.EmitCompactUnwind(Streamer, Frame);
}
const MCSection &Section = IsEH ? *MOFI->getEHFrameSection() :
*MOFI->getDwarfFrameSection();
Streamer.SwitchSection(&Section);
MCSymbol *SectionStart = Context.CreateTempSymbol();
Streamer.EmitLabel(SectionStart);
Emitter.setSectionStart(SectionStart);
MCSymbol *FDEEnd = NULL;
DenseMap<CIEKey, const MCSymbol*> CIEStarts;
const MCSymbol *DummyDebugKey = NULL;
for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) {
const MCDwarfFrameInfo &Frame = FrameArray[i];
CIEKey Key(Frame.Personality, Frame.PersonalityEncoding,
Frame.LsdaEncoding, Frame.IsSignalFrame);
const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey;
if (!CIEStart)
CIEStart = &Emitter.EmitCIE(Streamer, Frame.Personality,
Frame.PersonalityEncoding, Frame.Lsda,
Frame.IsSignalFrame,
Frame.LsdaEncoding);
FDEEnd = Emitter.EmitFDE(Streamer, *CIEStart, Frame);
if (i != n - 1)
Streamer.EmitLabel(FDEEnd);
}
Streamer.EmitValueToAlignment(Context.getAsmInfo().getPointerSize());
if (FDEEnd)
Streamer.EmitLabel(FDEEnd);
}
void MCDwarfFrameEmitter::EmitAdvanceLoc(MCStreamer &Streamer,
uint64_t AddrDelta) {
SmallString<256> Tmp;
raw_svector_ostream OS(Tmp);
MCDwarfFrameEmitter::EncodeAdvanceLoc(AddrDelta, OS);
Streamer.EmitBytes(OS.str());
}
void MCDwarfFrameEmitter::EncodeAdvanceLoc(uint64_t AddrDelta,
raw_ostream &OS) {
// FIXME: Assumes the code alignment factor is 1.
if (AddrDelta == 0) {
} else if (isUIntN(6, AddrDelta)) {
uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
OS << Opcode;
} else if (isUInt<8>(AddrDelta)) {
OS << uint8_t(dwarf::DW_CFA_advance_loc1);
OS << uint8_t(AddrDelta);
} else if (isUInt<16>(AddrDelta)) {
// FIXME: check what is the correct behavior on a big endian machine.
OS << uint8_t(dwarf::DW_CFA_advance_loc2);
OS << uint8_t( AddrDelta & 0xff);
OS << uint8_t((AddrDelta >> 8) & 0xff);
} else {
// FIXME: check what is the correct behavior on a big endian machine.
assert(isUInt<32>(AddrDelta));
OS << uint8_t(dwarf::DW_CFA_advance_loc4);
OS << uint8_t( AddrDelta & 0xff);
OS << uint8_t((AddrDelta >> 8) & 0xff);
OS << uint8_t((AddrDelta >> 16) & 0xff);
OS << uint8_t((AddrDelta >> 24) & 0xff);
}
}
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