Initial import.

1 files changed, 2199 insertions, 0 deletions

diff --git a/chromium/v8/src/gdb-jit.cc b/chromium/v8/src/gdb-jit.cc
new file mode 100644
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+++ b/chromium/v8/src/gdb-jit.cc
@@ -0,0 +1,2199 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifdef ENABLE_GDB_JIT_INTERFACE
+#include "v8.h"
+#include "gdb-jit.h"
+
+#include "bootstrapper.h"
+#include "compiler.h"
+#include "frames.h"
+#include "frames-inl.h"
+#include "global-handles.h"
+#include "messages.h"
+#include "natives.h"
+#include "platform.h"
+#include "scopes.h"
+
+namespace v8 {
+namespace internal {
+
+#ifdef __APPLE__
+#define __MACH_O
+class MachO;
+class MachOSection;
+typedef MachO DebugObject;
+typedef MachOSection DebugSection;
+#else
+#define __ELF
+class ELF;
+class ELFSection;
+typedef ELF DebugObject;
+typedef ELFSection DebugSection;
+#endif
+
+class Writer BASE_EMBEDDED {
+ public:
+  explicit Writer(DebugObject* debug_object)
+      : debug_object_(debug_object),
+        position_(0),
+        capacity_(1024),
+        buffer_(reinterpret_cast<byte*>(malloc(capacity_))) {
+  }
+
+  ~Writer() {
+    free(buffer_);
+  }
+
+  uintptr_t position() const {
+    return position_;
+  }
+
+  template<typename T>
+  class Slot {
+   public:
+    Slot(Writer* w, uintptr_t offset) : w_(w), offset_(offset) { }
+
+    T* operator-> () {
+      return w_->RawSlotAt<T>(offset_);
+    }
+
+    void set(const T& value) {
+      *w_->RawSlotAt<T>(offset_) = value;
+    }
+
+    Slot<T> at(int i) {
+      return Slot<T>(w_, offset_ + sizeof(T) * i);
+    }
+
+   private:
+    Writer* w_;
+    uintptr_t offset_;
+  };
+
+  template<typename T>
+  void Write(const T& val) {
+    Ensure(position_ + sizeof(T));
+    *RawSlotAt<T>(position_) = val;
+    position_ += sizeof(T);
+  }
+
+  template<typename T>
+  Slot<T> SlotAt(uintptr_t offset) {
+    Ensure(offset + sizeof(T));
+    return Slot<T>(this, offset);
+  }
+
+  template<typename T>
+  Slot<T> CreateSlotHere() {
+    return CreateSlotsHere<T>(1);
+  }
+
+  template<typename T>
+  Slot<T> CreateSlotsHere(uint32_t count) {
+    uintptr_t slot_position = position_;
+    position_ += sizeof(T) * count;
+    Ensure(position_);
+    return SlotAt<T>(slot_position);
+  }
+
+  void Ensure(uintptr_t pos) {
+    if (capacity_ < pos) {
+      while (capacity_ < pos) capacity_ *= 2;
+      buffer_ = reinterpret_cast<byte*>(realloc(buffer_, capacity_));
+    }
+  }
+
+  DebugObject* debug_object() { return debug_object_; }
+
+  byte* buffer() { return buffer_; }
+
+  void Align(uintptr_t align) {
+    uintptr_t delta = position_ % align;
+    if (delta == 0) return;
+    uintptr_t padding = align - delta;
+    Ensure(position_ += padding);
+    ASSERT((position_ % align) == 0);
+  }
+
+  void WriteULEB128(uintptr_t value) {
+    do {
+      uint8_t byte = value & 0x7F;
+      value >>= 7;
+      if (value != 0) byte |= 0x80;
+      Write<uint8_t>(byte);
+    } while (value != 0);
+  }
+
+  void WriteSLEB128(intptr_t value) {
+    bool more = true;
+    while (more) {
+      int8_t byte = value & 0x7F;
+      bool byte_sign = byte & 0x40;
+      value >>= 7;
+
+      if ((value == 0 && !byte_sign) || (value == -1 && byte_sign)) {
+        more = false;
+      } else {
+        byte |= 0x80;
+      }
+
+      Write<int8_t>(byte);
+    }
+  }
+
+  void WriteString(const char* str) {
+    do {
+      Write<char>(*str);
+    } while (*str++);
+  }
+
+ private:
+  template<typename T> friend class Slot;
+
+  template<typename T>
+  T* RawSlotAt(uintptr_t offset) {
+    ASSERT(offset < capacity_ && offset + sizeof(T) <= capacity_);
+    return reinterpret_cast<T*>(&buffer_[offset]);
+  }
+
+  DebugObject* debug_object_;
+  uintptr_t position_;
+  uintptr_t capacity_;
+  byte* buffer_;
+};
+
+class ELFStringTable;
+
+template<typename THeader>
+class DebugSectionBase : public ZoneObject {
+ public:
+  virtual ~DebugSectionBase() { }
+
+  virtual void WriteBody(Writer::Slot<THeader> header, Writer* writer) {
+    uintptr_t start = writer->position();
+    if (WriteBodyInternal(writer)) {
+      uintptr_t end = writer->position();
+      header->offset = start;
+#if defined(__MACH_O)
+      header->addr = 0;
+#endif
+      header->size = end - start;
+    }
+  }
+
+  virtual bool WriteBodyInternal(Writer* writer) {
+    return false;
+  }
+
+  typedef THeader Header;
+};
+
+
+struct MachOSectionHeader {
+  char sectname[16];
+  char segname[16];
+#if V8_TARGET_ARCH_IA32
+  uint32_t addr;
+  uint32_t size;
+#else
+  uint64_t addr;
+  uint64_t size;
+#endif
+  uint32_t offset;
+  uint32_t align;
+  uint32_t reloff;
+  uint32_t nreloc;
+  uint32_t flags;
+  uint32_t reserved1;
+  uint32_t reserved2;
+};
+
+
+class MachOSection : public DebugSectionBase<MachOSectionHeader> {
+ public:
+  enum Type {
+    S_REGULAR = 0x0u,
+    S_ATTR_COALESCED = 0xbu,
+    S_ATTR_SOME_INSTRUCTIONS = 0x400u,
+    S_ATTR_DEBUG = 0x02000000u,
+    S_ATTR_PURE_INSTRUCTIONS = 0x80000000u
+  };
+
+  MachOSection(const char* name,
+               const char* segment,
+               uintptr_t align,
+               uint32_t flags)
+    : name_(name),
+      segment_(segment),
+      align_(align),
+      flags_(flags) {
+    ASSERT(IsPowerOf2(align));
+    if (align_ != 0) {
+      align_ = WhichPowerOf2(align_);
+    }
+  }
+
+  virtual ~MachOSection() { }
+
+  virtual void PopulateHeader(Writer::Slot<Header> header) {
+    header->addr = 0;
+    header->size = 0;
+    header->offset = 0;
+    header->align = align_;
+    header->reloff = 0;
+    header->nreloc = 0;
+    header->flags = flags_;
+    header->reserved1 = 0;
+    header->reserved2 = 0;
+    memset(header->sectname, 0, sizeof(header->sectname));
+    memset(header->segname, 0, sizeof(header->segname));
+    ASSERT(strlen(name_) < sizeof(header->sectname));
+    ASSERT(strlen(segment_) < sizeof(header->segname));
+    strncpy(header->sectname, name_, sizeof(header->sectname));
+    strncpy(header->segname, segment_, sizeof(header->segname));
+  }
+
+ private:
+  const char* name_;
+  const char* segment_;
+  uintptr_t align_;
+  uint32_t flags_;
+};
+
+
+struct ELFSectionHeader {
+  uint32_t name;
+  uint32_t type;
+  uintptr_t flags;
+  uintptr_t address;
+  uintptr_t offset;
+  uintptr_t size;
+  uint32_t link;
+  uint32_t info;
+  uintptr_t alignment;
+  uintptr_t entry_size;
+};
+
+
+#if defined(__ELF)
+class ELFSection : public DebugSectionBase<ELFSectionHeader> {
+ public:
+  enum Type {
+    TYPE_NULL = 0,
+    TYPE_PROGBITS = 1,
+    TYPE_SYMTAB = 2,
+    TYPE_STRTAB = 3,
+    TYPE_RELA = 4,
+    TYPE_HASH = 5,
+    TYPE_DYNAMIC = 6,
+    TYPE_NOTE = 7,
+    TYPE_NOBITS = 8,
+    TYPE_REL = 9,
+    TYPE_SHLIB = 10,
+    TYPE_DYNSYM = 11,
+    TYPE_LOPROC = 0x70000000,
+    TYPE_X86_64_UNWIND = 0x70000001,
+    TYPE_HIPROC = 0x7fffffff,
+    TYPE_LOUSER = 0x80000000,
+    TYPE_HIUSER = 0xffffffff
+  };
+
+  enum Flags {
+    FLAG_WRITE = 1,
+    FLAG_ALLOC = 2,
+    FLAG_EXEC = 4
+  };
+
+  enum SpecialIndexes {
+    INDEX_ABSOLUTE = 0xfff1
+  };
+
+  ELFSection(const char* name, Type type, uintptr_t align)
+      : name_(name), type_(type), align_(align) { }
+
+  virtual ~ELFSection() { }
+
+  void PopulateHeader(Writer::Slot<Header> header, ELFStringTable* strtab);
+
+  virtual void WriteBody(Writer::Slot<Header> header, Writer* w) {
+    uintptr_t start = w->position();
+    if (WriteBodyInternal(w)) {
+      uintptr_t end = w->position();
+      header->offset = start;
+      header->size = end - start;
+    }
+  }
+
+  virtual bool WriteBodyInternal(Writer* w) {
+    return false;
+  }
+
+  uint16_t index() const { return index_; }
+  void set_index(uint16_t index) { index_ = index; }
+
+ protected:
+  virtual void PopulateHeader(Writer::Slot<Header> header) {
+    header->flags = 0;
+    header->address = 0;
+    header->offset = 0;
+    header->size = 0;
+    header->link = 0;
+    header->info = 0;
+    header->entry_size = 0;
+  }
+
+ private:
+  const char* name_;
+  Type type_;
+  uintptr_t align_;
+  uint16_t index_;
+};
+#endif  // defined(__ELF)
+
+
+#if defined(__MACH_O)
+class MachOTextSection : public MachOSection {
+ public:
+  MachOTextSection(uintptr_t align,
+                   uintptr_t addr,
+                   uintptr_t size)
+      : MachOSection("__text",
+                     "__TEXT",
+                     align,
+                     MachOSection::S_REGULAR |
+                         MachOSection::S_ATTR_SOME_INSTRUCTIONS |
+                         MachOSection::S_ATTR_PURE_INSTRUCTIONS),
+        addr_(addr),
+        size_(size) { }
+
+ protected:
+  virtual void PopulateHeader(Writer::Slot<Header> header) {
+    MachOSection::PopulateHeader(header);
+    header->addr = addr_;
+    header->size = size_;
+  }
+
+ private:
+  uintptr_t addr_;
+  uintptr_t size_;
+};
+#endif  // defined(__MACH_O)
+
+
+#if defined(__ELF)
+class FullHeaderELFSection : public ELFSection {
+ public:
+  FullHeaderELFSection(const char* name,
+                       Type type,
+                       uintptr_t align,
+                       uintptr_t addr,
+                       uintptr_t offset,
+                       uintptr_t size,
+                       uintptr_t flags)
+      : ELFSection(name, type, align),
+        addr_(addr),
+        offset_(offset),
+        size_(size),
+        flags_(flags) { }
+
+ protected:
+  virtual void PopulateHeader(Writer::Slot<Header> header) {
+    ELFSection::PopulateHeader(header);
+    header->address = addr_;
+    header->offset = offset_;
+    header->size = size_;
+    header->flags = flags_;
+  }
+
+ private:
+  uintptr_t addr_;
+  uintptr_t offset_;
+  uintptr_t size_;
+  uintptr_t flags_;
+};
+
+
+class ELFStringTable : public ELFSection {
+ public:
+  explicit ELFStringTable(const char* name)
+      : ELFSection(name, TYPE_STRTAB, 1), writer_(NULL), offset_(0), size_(0) {
+  }
+
+  uintptr_t Add(const char* str) {
+    if (*str == '\0') return 0;
+
+    uintptr_t offset = size_;
+    WriteString(str);
+    return offset;
+  }
+
+  void AttachWriter(Writer* w) {
+    writer_ = w;
+    offset_ = writer_->position();
+
+    // First entry in the string table should be an empty string.
+    WriteString("");
+  }
+
+  void DetachWriter() {
+    writer_ = NULL;
+  }
+
+  virtual void WriteBody(Writer::Slot<Header> header, Writer* w) {
+    ASSERT(writer_ == NULL);
+    header->offset = offset_;
+    header->size = size_;
+  }
+
+ private:
+  void WriteString(const char* str) {
+    uintptr_t written = 0;
+    do {
+      writer_->Write(*str);
+      written++;
+    } while (*str++);
+    size_ += written;
+  }
+
+  Writer* writer_;
+
+  uintptr_t offset_;
+  uintptr_t size_;
+};
+
+
+void ELFSection::PopulateHeader(Writer::Slot<ELFSection::Header> header,
+                                ELFStringTable* strtab) {
+  header->name = strtab->Add(name_);
+  header->type = type_;
+  header->alignment = align_;
+  PopulateHeader(header);
+}
+#endif  // defined(__ELF)
+
+
+#if defined(__MACH_O)
+class MachO BASE_EMBEDDED {
+ public:
+  explicit MachO(Zone* zone) : zone_(zone), sections_(6, zone) { }
+
+  uint32_t AddSection(MachOSection* section) {
+    sections_.Add(section, zone_);
+    return sections_.length() - 1;
+  }
+
+  void Write(Writer* w, uintptr_t code_start, uintptr_t code_size) {
+    Writer::Slot<MachOHeader> header = WriteHeader(w);
+    uintptr_t load_command_start = w->position();
+    Writer::Slot<MachOSegmentCommand> cmd = WriteSegmentCommand(w,
+                                                                code_start,
+                                                                code_size);
+    WriteSections(w, cmd, header, load_command_start);
+  }
+
+ private:
+  struct MachOHeader {
+    uint32_t magic;
+    uint32_t cputype;
+    uint32_t cpusubtype;
+    uint32_t filetype;
+    uint32_t ncmds;
+    uint32_t sizeofcmds;
+    uint32_t flags;
+#if V8_TARGET_ARCH_X64
+    uint32_t reserved;
+#endif
+  };
+
+  struct MachOSegmentCommand {
+    uint32_t cmd;
+    uint32_t cmdsize;
+    char segname[16];
+#if V8_TARGET_ARCH_IA32
+    uint32_t vmaddr;
+    uint32_t vmsize;
+    uint32_t fileoff;
+    uint32_t filesize;
+#else
+    uint64_t vmaddr;
+    uint64_t vmsize;
+    uint64_t fileoff;
+    uint64_t filesize;
+#endif
+    uint32_t maxprot;
+    uint32_t initprot;
+    uint32_t nsects;
+    uint32_t flags;
+  };
+
+  enum MachOLoadCommandCmd {
+    LC_SEGMENT_32 = 0x00000001u,
+    LC_SEGMENT_64 = 0x00000019u
+  };
+
+
+  Writer::Slot<MachOHeader> WriteHeader(Writer* w) {
+    ASSERT(w->position() == 0);
+    Writer::Slot<MachOHeader> header = w->CreateSlotHere<MachOHeader>();
+#if V8_TARGET_ARCH_IA32
+    header->magic = 0xFEEDFACEu;
+    header->cputype = 7;  // i386
+    header->cpusubtype = 3;  // CPU_SUBTYPE_I386_ALL
+#elif V8_TARGET_ARCH_X64
+    header->magic = 0xFEEDFACFu;
+    header->cputype = 7 | 0x01000000;  // i386 | 64-bit ABI
+    header->cpusubtype = 3;  // CPU_SUBTYPE_I386_ALL
+    header->reserved = 0;
+#else
+#error Unsupported target architecture.
+#endif
+    header->filetype = 0x1;  // MH_OBJECT
+    header->ncmds = 1;
+    header->sizeofcmds = 0;
+    header->flags = 0;
+    return header;
+  }
+
+
+  Writer::Slot<MachOSegmentCommand> WriteSegmentCommand(Writer* w,
+                                                        uintptr_t code_start,
+                                                        uintptr_t code_size) {
+    Writer::Slot<MachOSegmentCommand> cmd =
+        w->CreateSlotHere<MachOSegmentCommand>();
+#if V8_TARGET_ARCH_IA32
+    cmd->cmd = LC_SEGMENT_32;
+#else
+    cmd->cmd = LC_SEGMENT_64;
+#endif
+    cmd->vmaddr = code_start;
+    cmd->vmsize = code_size;
+    cmd->fileoff = 0;
+    cmd->filesize = 0;
+    cmd->maxprot = 7;
+    cmd->initprot = 7;
+    cmd->flags = 0;
+    cmd->nsects = sections_.length();
+    memset(cmd->segname, 0, 16);
+    cmd->cmdsize = sizeof(MachOSegmentCommand) + sizeof(MachOSection::Header) *
+        cmd->nsects;
+    return cmd;
+  }
+
+
+  void WriteSections(Writer* w,
+                     Writer::Slot<MachOSegmentCommand> cmd,
+                     Writer::Slot<MachOHeader> header,
+                     uintptr_t load_command_start) {
+    Writer::Slot<MachOSection::Header> headers =
+        w->CreateSlotsHere<MachOSection::Header>(sections_.length());
+    cmd->fileoff = w->position();
+    header->sizeofcmds = w->position() - load_command_start;
+    for (int section = 0; section < sections_.length(); ++section) {
+      sections_[section]->PopulateHeader(headers.at(section));
+      sections_[section]->WriteBody(headers.at(section), w);
+    }
+    cmd->filesize = w->position() - (uintptr_t)cmd->fileoff;
+  }
+
+  Zone* zone_;
+  ZoneList<MachOSection*> sections_;
+};
+#endif  // defined(__MACH_O)
+
+
+#if defined(__ELF)
+class ELF BASE_EMBEDDED {
+ public:
+  explicit ELF(Zone* zone) : zone_(zone), sections_(6, zone) {
+    sections_.Add(new(zone) ELFSection("", ELFSection::TYPE_NULL, 0), zone);
+    sections_.Add(new(zone) ELFStringTable(".shstrtab"), zone);
+  }
+
+  void Write(Writer* w) {
+    WriteHeader(w);
+    WriteSectionTable(w);
+    WriteSections(w);
+  }
+
+  ELFSection* SectionAt(uint32_t index) {
+    return sections_[index];
+  }
+
+  uint32_t AddSection(ELFSection* section) {
+    sections_.Add(section, zone_);
+    section->set_index(sections_.length() - 1);
+    return sections_.length() - 1;
+  }
+
+ private:
+  struct ELFHeader {
+    uint8_t ident[16];
+    uint16_t type;
+    uint16_t machine;
+    uint32_t version;
+    uintptr_t entry;
+    uintptr_t pht_offset;
+    uintptr_t sht_offset;
+    uint32_t flags;
+    uint16_t header_size;
+    uint16_t pht_entry_size;
+    uint16_t pht_entry_num;
+    uint16_t sht_entry_size;
+    uint16_t sht_entry_num;
+    uint16_t sht_strtab_index;
+  };
+
+
+  void WriteHeader(Writer* w) {
+    ASSERT(w->position() == 0);
+    Writer::Slot<ELFHeader> header = w->CreateSlotHere<ELFHeader>();
+#if V8_TARGET_ARCH_IA32 || V8_TARGET_ARCH_ARM
+    const uint8_t ident[16] =
+        { 0x7f, 'E', 'L', 'F', 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+#elif V8_TARGET_ARCH_X64
+    const uint8_t ident[16] =
+        { 0x7f, 'E', 'L', 'F', 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+#else
+#error Unsupported target architecture.
+#endif
+    OS::MemCopy(header->ident, ident, 16);
+    header->type = 1;
+#if V8_TARGET_ARCH_IA32
+    header->machine = 3;
+#elif V8_TARGET_ARCH_X64
+    // Processor identification value for x64 is 62 as defined in
+    //    System V ABI, AMD64 Supplement
+    //    http://www.x86-64.org/documentation/abi.pdf
+    header->machine = 62;
+#elif V8_TARGET_ARCH_ARM
+    // Set to EM_ARM, defined as 40, in "ARM ELF File Format" at
+    // infocenter.arm.com/help/topic/com.arm.doc.dui0101a/DUI0101A_Elf.pdf
+    header->machine = 40;
+#else
+#error Unsupported target architecture.
+#endif
+    header->version = 1;
+    header->entry = 0;
+    header->pht_offset = 0;
+    header->sht_offset = sizeof(ELFHeader);  // Section table follows header.
+    header->flags = 0;
+    header->header_size = sizeof(ELFHeader);
+    header->pht_entry_size = 0;
+    header->pht_entry_num = 0;
+    header->sht_entry_size = sizeof(ELFSection::Header);
+    header->sht_entry_num = sections_.length();
+    header->sht_strtab_index = 1;
+  }
+
+  void WriteSectionTable(Writer* w) {
+    // Section headers table immediately follows file header.
+    ASSERT(w->position() == sizeof(ELFHeader));
+
+    Writer::Slot<ELFSection::Header> headers =
+        w->CreateSlotsHere<ELFSection::Header>(sections_.length());
+
+    // String table for section table is the first section.
+    ELFStringTable* strtab = static_cast<ELFStringTable*>(SectionAt(1));
+    strtab->AttachWriter(w);
+    for (int i = 0, length = sections_.length();
+         i < length;
+         i++) {
+      sections_[i]->PopulateHeader(headers.at(i), strtab);
+    }
+    strtab->DetachWriter();
+  }
+
+  int SectionHeaderPosition(uint32_t section_index) {
+    return sizeof(ELFHeader) + sizeof(ELFSection::Header) * section_index;
+  }
+
+  void WriteSections(Writer* w) {
+    Writer::Slot<ELFSection::Header> headers =
+        w->SlotAt<ELFSection::Header>(sizeof(ELFHeader));
+
+    for (int i = 0, length = sections_.length();
+         i < length;
+         i++) {
+      sections_[i]->WriteBody(headers.at(i), w);
+    }
+  }
+
+  Zone* zone_;
+  ZoneList<ELFSection*> sections_;
+};
+
+
+class ELFSymbol BASE_EMBEDDED {
+ public:
+  enum Type {
+    TYPE_NOTYPE = 0,
+    TYPE_OBJECT = 1,
+    TYPE_FUNC = 2,
+    TYPE_SECTION = 3,
+    TYPE_FILE = 4,
+    TYPE_LOPROC = 13,
+    TYPE_HIPROC = 15
+  };
+
+  enum Binding {
+    BIND_LOCAL = 0,
+    BIND_GLOBAL = 1,
+    BIND_WEAK = 2,
+    BIND_LOPROC = 13,
+    BIND_HIPROC = 15
+  };
+
+  ELFSymbol(const char* name,
+            uintptr_t value,
+            uintptr_t size,
+            Binding binding,
+            Type type,
+            uint16_t section)
+      : name(name),
+        value(value),
+        size(size),
+        info((binding << 4) | type),
+        other(0),
+        section(section) {
+  }
+
+  Binding binding() const {
+    return static_cast<Binding>(info >> 4);
+  }
+#if V8_TARGET_ARCH_IA32 || V8_TARGET_ARCH_ARM
+  struct SerializedLayout {
+    SerializedLayout(uint32_t name,
+                     uintptr_t value,
+                     uintptr_t size,
+                     Binding binding,
+                     Type type,
+                     uint16_t section)
+        : name(name),
+          value(value),
+          size(size),
+          info((binding << 4) | type),
+          other(0),
+          section(section) {
+    }
+
+    uint32_t name;
+    uintptr_t value;
+    uintptr_t size;
+    uint8_t info;
+    uint8_t other;
+    uint16_t section;
+  };
+#elif V8_TARGET_ARCH_X64
+  struct SerializedLayout {
+    SerializedLayout(uint32_t name,
+                     uintptr_t value,
+                     uintptr_t size,
+                     Binding binding,
+                     Type type,
+                     uint16_t section)
+        : name(name),
+          info((binding << 4) | type),
+          other(0),
+          section(section),
+          value(value),
+          size(size) {
+    }
+
+    uint32_t name;
+    uint8_t info;
+    uint8_t other;
+    uint16_t section;
+    uintptr_t value;
+    uintptr_t size;
+  };
+#endif
+
+  void Write(Writer::Slot<SerializedLayout> s, ELFStringTable* t) {
+    // Convert symbol names from strings to indexes in the string table.
+    s->name = t->Add(name);
+    s->value = value;
+    s->size = size;
+    s->info = info;
+    s->other = other;
+    s->section = section;
+  }
+
+ private:
+  const char* name;
+  uintptr_t value;
+  uintptr_t size;
+  uint8_t info;
+  uint8_t other;
+  uint16_t section;
+};
+
+
+class ELFSymbolTable : public ELFSection {
+ public:
+  ELFSymbolTable(const char* name, Zone* zone)
+      : ELFSection(name, TYPE_SYMTAB, sizeof(uintptr_t)),
+        locals_(1, zone),
+        globals_(1, zone) {
+  }
+
+  virtual void WriteBody(Writer::Slot<Header> header, Writer* w) {
+    w->Align(header->alignment);
+    int total_symbols = locals_.length() + globals_.length() + 1;
+    header->offset = w->position();
+
+    Writer::Slot<ELFSymbol::SerializedLayout> symbols =
+        w->CreateSlotsHere<ELFSymbol::SerializedLayout>(total_symbols);
+
+    header->size = w->position() - header->offset;
+
+    // String table for this symbol table should follow it in the section table.
+    ELFStringTable* strtab =
+        static_cast<ELFStringTable*>(w->debug_object()->SectionAt(index() + 1));
+    strtab->AttachWriter(w);
+    symbols.at(0).set(ELFSymbol::SerializedLayout(0,
+                                                  0,
+                                                  0,
+                                                  ELFSymbol::BIND_LOCAL,
+                                                  ELFSymbol::TYPE_NOTYPE,
+                                                  0));
+    WriteSymbolsList(&locals_, symbols.at(1), strtab);
+    WriteSymbolsList(&globals_, symbols.at(locals_.length() + 1), strtab);
+    strtab->DetachWriter();
+  }
+
+  void Add(const ELFSymbol& symbol, Zone* zone) {
+    if (symbol.binding() == ELFSymbol::BIND_LOCAL) {
+      locals_.Add(symbol, zone);
+    } else {
+      globals_.Add(symbol, zone);
+    }
+  }
+
+ protected:
+  virtual void PopulateHeader(Writer::Slot<Header> header) {
+    ELFSection::PopulateHeader(header);
+    // We are assuming that string table will follow symbol table.
+    header->link = index() + 1;
+    header->info = locals_.length() + 1;
+    header->entry_size = sizeof(ELFSymbol::SerializedLayout);
+  }
+
+ private:
+  void WriteSymbolsList(const ZoneList<ELFSymbol>* src,
+                        Writer::Slot<ELFSymbol::SerializedLayout> dst,
+                        ELFStringTable* strtab) {
+    for (int i = 0, len = src->length();
+         i < len;
+         i++) {
+      src->at(i).Write(dst.at(i), strtab);
+    }
+  }
+
+  ZoneList<ELFSymbol> locals_;
+  ZoneList<ELFSymbol> globals_;
+};
+#endif  // defined(__ELF)
+
+
+class CodeDescription BASE_EMBEDDED {
+ public:
+#if V8_TARGET_ARCH_X64
+  enum StackState {
+    POST_RBP_PUSH,
+    POST_RBP_SET,
+    POST_RBP_POP,
+    STACK_STATE_MAX
+  };
+#endif
+
+  CodeDescription(const char* name,
+                  Code* code,
+                  Handle<Script> script,
+                  GDBJITLineInfo* lineinfo,
+                  GDBJITInterface::CodeTag tag,
+                  CompilationInfo* info)
+      : name_(name),
+        code_(code),
+        script_(script),
+        lineinfo_(lineinfo),
+        tag_(tag),
+        info_(info) {
+  }
+
+  const char* name() const {
+    return name_;
+  }
+
+  GDBJITLineInfo* lineinfo() const {
+    return lineinfo_;
+  }
+
+  GDBJITInterface::CodeTag tag() const {
+    return tag_;
+  }
+
+  CompilationInfo* info() const {
+    return info_;
+  }
+
+  bool IsInfoAvailable() const {
+    return info_ != NULL;
+  }
+
+  uintptr_t CodeStart() const {
+    return reinterpret_cast<uintptr_t>(code_->instruction_start());
+  }
+
+  uintptr_t CodeEnd() const {
+    return reinterpret_cast<uintptr_t>(code_->instruction_end());
+  }
+
+  uintptr_t CodeSize() const {
+    return CodeEnd() - CodeStart();
+  }
+
+  bool IsLineInfoAvailable() {
+    return !script_.is_null() &&
+        script_->source()->IsString() &&
+        script_->HasValidSource() &&
+        script_->name()->IsString() &&
+        lineinfo_ != NULL;
+  }
+
+#if V8_TARGET_ARCH_X64
+  uintptr_t GetStackStateStartAddress(StackState state) const {
+    ASSERT(state < STACK_STATE_MAX);
+    return stack_state_start_addresses_[state];
+  }
+
+  void SetStackStateStartAddress(StackState state, uintptr_t addr) {
+    ASSERT(state < STACK_STATE_MAX);
+    stack_state_start_addresses_[state] = addr;
+  }
+#endif
+
+  SmartArrayPointer<char> GetFilename() {
+    return String::cast(script_->name())->ToCString();
+  }
+
+  int GetScriptLineNumber(int pos) {
+    return GetScriptLineNumberSafe(script_, pos) + 1;
+  }
+
+
+ private:
+  const char* name_;
+  Code* code_;
+  Handle<Script> script_;
+  GDBJITLineInfo* lineinfo_;
+  GDBJITInterface::CodeTag tag_;
+  CompilationInfo* info_;
+#if V8_TARGET_ARCH_X64
+  uintptr_t stack_state_start_addresses_[STACK_STATE_MAX];
+#endif
+};
+
+#if defined(__ELF)
+static void CreateSymbolsTable(CodeDescription* desc,
+                               Zone* zone,
+                               ELF* elf,
+                               int text_section_index) {
+  ELFSymbolTable* symtab = new(zone) ELFSymbolTable(".symtab", zone);
+  ELFStringTable* strtab = new(zone) ELFStringTable(".strtab");
+
+  // Symbol table should be followed by the linked string table.
+  elf->AddSection(symtab);
+  elf->AddSection(strtab);
+
+  symtab->Add(ELFSymbol("V8 Code",
+                        0,
+                        0,
+                        ELFSymbol::BIND_LOCAL,
+                        ELFSymbol::TYPE_FILE,
+                        ELFSection::INDEX_ABSOLUTE),
+              zone);
+
+  symtab->Add(ELFSymbol(desc->name(),
+                        0,
+                        desc->CodeSize(),
+                        ELFSymbol::BIND_GLOBAL,
+                        ELFSymbol::TYPE_FUNC,
+                        text_section_index),
+              zone);
+}
+#endif  // defined(__ELF)
+
+
+class DebugInfoSection : public DebugSection {
+ public:
+  explicit DebugInfoSection(CodeDescription* desc)
+#if defined(__ELF)
+      : ELFSection(".debug_info", TYPE_PROGBITS, 1),
+#else
+      : MachOSection("__debug_info",
+                     "__DWARF",
+                     1,
+                     MachOSection::S_REGULAR | MachOSection::S_ATTR_DEBUG),
+#endif
+        desc_(desc) { }
+
+  // DWARF2 standard
+  enum DWARF2LocationOp {
+    DW_OP_reg0 = 0x50,
+    DW_OP_reg1 = 0x51,
+    DW_OP_reg2 = 0x52,
+    DW_OP_reg3 = 0x53,
+    DW_OP_reg4 = 0x54,
+    DW_OP_reg5 = 0x55,
+    DW_OP_reg6 = 0x56,
+    DW_OP_reg7 = 0x57,
+    DW_OP_fbreg = 0x91  // 1 param: SLEB128 offset
+  };
+
+  enum DWARF2Encoding {
+    DW_ATE_ADDRESS = 0x1,
+    DW_ATE_SIGNED = 0x5
+  };
+
+  bool WriteBodyInternal(Writer* w) {
+    uintptr_t cu_start = w->position();
+    Writer::Slot<uint32_t> size = w->CreateSlotHere<uint32_t>();
+    uintptr_t start = w->position();
+    w->Write<uint16_t>(2);  // DWARF version.
+    w->Write<uint32_t>(0);  // Abbreviation table offset.
+    w->Write<uint8_t>(sizeof(intptr_t));
+
+    w->WriteULEB128(1);  // Abbreviation code.
+    w->WriteString(*desc_->GetFilename());
+    w->Write<intptr_t>(desc_->CodeStart());
+    w->Write<intptr_t>(desc_->CodeStart() + desc_->CodeSize());
+    w->Write<uint32_t>(0);
+
+    uint32_t ty_offset = static_cast<uint32_t>(w->position() - cu_start);
+    w->WriteULEB128(3);
+    w->Write<uint8_t>(kPointerSize);
+    w->WriteString("v8value");
+
+    if (desc_->IsInfoAvailable()) {
+      Scope* scope = desc_->info()->scope();
+      w->WriteULEB128(2);
+      w->WriteString(desc_->name());
+      w->Write<intptr_t>(desc_->CodeStart());
+      w->Write<intptr_t>(desc_->CodeStart() + desc_->CodeSize());
+      Writer::Slot<uint32_t> fb_block_size = w->CreateSlotHere<uint32_t>();
+      uintptr_t fb_block_start = w->position();
+#if V8_TARGET_ARCH_IA32
+      w->Write<uint8_t>(DW_OP_reg5);  // The frame pointer's here on ia32
+#elif V8_TARGET_ARCH_X64
+      w->Write<uint8_t>(DW_OP_reg6);  // and here on x64.
+#elif V8_TARGET_ARCH_ARM
+      UNIMPLEMENTED();
+#elif V8_TARGET_ARCH_MIPS
+      UNIMPLEMENTED();
+#else
+#error Unsupported target architecture.
+#endif
+      fb_block_size.set(static_cast<uint32_t>(w->position() - fb_block_start));
+
+      int params = scope->num_parameters();
+      int slots = scope->num_stack_slots();
+      int context_slots = scope->ContextLocalCount();
+      // The real slot ID is internal_slots + context_slot_id.
+      int internal_slots = Context::MIN_CONTEXT_SLOTS;
+      int locals = scope->StackLocalCount();
+      int current_abbreviation = 4;
+
+      for (int param = 0; param < params; ++param) {
+        w->WriteULEB128(current_abbreviation++);
+        w->WriteString(
+            *scope->parameter(param)->name()->ToCString(DISALLOW_NULLS));
+        w->Write<uint32_t>(ty_offset);
+        Writer::Slot<uint32_t> block_size = w->CreateSlotHere<uint32_t>();
+        uintptr_t block_start = w->position();
+        w->Write<uint8_t>(DW_OP_fbreg);
+        w->WriteSLEB128(
+          JavaScriptFrameConstants::kLastParameterOffset +
+              kPointerSize * (params - param - 1));
+        block_size.set(static_cast<uint32_t>(w->position() - block_start));
+      }
+
+      EmbeddedVector<char, 256> buffer;
+      StringBuilder builder(buffer.start(), buffer.length());
+
+      for (int slot = 0; slot < slots; ++slot) {
+        w->WriteULEB128(current_abbreviation++);
+        builder.Reset();
+        builder.AddFormatted("slot%d", slot);
+        w->WriteString(builder.Finalize());
+      }
+
+      // See contexts.h for more information.
+      ASSERT(Context::MIN_CONTEXT_SLOTS == 4);
+      ASSERT(Context::CLOSURE_INDEX == 0);
+      ASSERT(Context::PREVIOUS_INDEX == 1);
+      ASSERT(Context::EXTENSION_INDEX == 2);
+      ASSERT(Context::GLOBAL_OBJECT_INDEX == 3);
+      w->WriteULEB128(current_abbreviation++);
+      w->WriteString(".closure");
+      w->WriteULEB128(current_abbreviation++);
+      w->WriteString(".previous");
+      w->WriteULEB128(current_abbreviation++);
+      w->WriteString(".extension");
+      w->WriteULEB128(current_abbreviation++);
+      w->WriteString(".global");
+
+      for (int context_slot = 0;
+           context_slot < context_slots;
+           ++context_slot) {
+        w->WriteULEB128(current_abbreviation++);
+        builder.Reset();
+        builder.AddFormatted("context_slot%d", context_slot + internal_slots);
+        w->WriteString(builder.Finalize());
+      }
+
+      ZoneList<Variable*> stack_locals(locals, scope->zone());
+      ZoneList<Variable*> context_locals(context_slots, scope->zone());
+      scope->CollectStackAndContextLocals(&stack_locals, &context_locals);
+      for (int local = 0; local < locals; ++local) {
+        w->WriteULEB128(current_abbreviation++);
+        w->WriteString(
+            *stack_locals[local]->name()->ToCString(DISALLOW_NULLS));
+        w->Write<uint32_t>(ty_offset);
+        Writer::Slot<uint32_t> block_size = w->CreateSlotHere<uint32_t>();
+        uintptr_t block_start = w->position();
+        w->Write<uint8_t>(DW_OP_fbreg);
+        w->WriteSLEB128(
+          JavaScriptFrameConstants::kLocal0Offset -
+              kPointerSize * local);
+        block_size.set(static_cast<uint32_t>(w->position() - block_start));
+      }
+
+      {
+        w->WriteULEB128(current_abbreviation++);
+        w->WriteString("__function");
+        w->Write<uint32_t>(ty_offset);
+        Writer::Slot<uint32_t> block_size = w->CreateSlotHere<uint32_t>();
+        uintptr_t block_start = w->position();
+        w->Write<uint8_t>(DW_OP_fbreg);
+        w->WriteSLEB128(JavaScriptFrameConstants::kFunctionOffset);
+        block_size.set(static_cast<uint32_t>(w->position() - block_start));
+      }
+
+      {
+        w->WriteULEB128(current_abbreviation++);
+        w->WriteString("__context");
+        w->Write<uint32_t>(ty_offset);
+        Writer::Slot<uint32_t> block_size = w->CreateSlotHere<uint32_t>();
+        uintptr_t block_start = w->position();
+        w->Write<uint8_t>(DW_OP_fbreg);
+        w->WriteSLEB128(StandardFrameConstants::kContextOffset);
+        block_size.set(static_cast<uint32_t>(w->position() - block_start));
+      }
+
+      w->WriteULEB128(0);  // Terminate the sub program.
+    }
+
+    w->WriteULEB128(0);  // Terminate the compile unit.
+    size.set(static_cast<uint32_t>(w->position() - start));
+    return true;
+  }
+
+ private:
+  CodeDescription* desc_;
+};
+
+
+class DebugAbbrevSection : public DebugSection {
+ public:
+  explicit DebugAbbrevSection(CodeDescription* desc)
+#ifdef __ELF
+      : ELFSection(".debug_abbrev", TYPE_PROGBITS, 1),
+#else
+      : MachOSection("__debug_abbrev",
+                     "__DWARF",
+                     1,
+                     MachOSection::S_REGULAR | MachOSection::S_ATTR_DEBUG),
+#endif
+        desc_(desc) { }
+
+  // DWARF2 standard, figure 14.
+  enum DWARF2Tags {
+    DW_TAG_FORMAL_PARAMETER = 0x05,
+    DW_TAG_POINTER_TYPE = 0xf,
+    DW_TAG_COMPILE_UNIT = 0x11,
+    DW_TAG_STRUCTURE_TYPE = 0x13,
+    DW_TAG_BASE_TYPE = 0x24,
+    DW_TAG_SUBPROGRAM = 0x2e,
+    DW_TAG_VARIABLE = 0x34
+  };
+
+  // DWARF2 standard, figure 16.
+  enum DWARF2ChildrenDetermination {
+    DW_CHILDREN_NO = 0,
+    DW_CHILDREN_YES = 1
+  };
+
+  // DWARF standard, figure 17.
+  enum DWARF2Attribute {
+    DW_AT_LOCATION = 0x2,
+    DW_AT_NAME = 0x3,
+    DW_AT_BYTE_SIZE = 0xb,
+    DW_AT_STMT_LIST = 0x10,
+    DW_AT_LOW_PC = 0x11,
+    DW_AT_HIGH_PC = 0x12,
+    DW_AT_ENCODING = 0x3e,
+    DW_AT_FRAME_BASE = 0x40,
+    DW_AT_TYPE = 0x49
+  };
+
+  // DWARF2 standard, figure 19.
+  enum DWARF2AttributeForm {
+    DW_FORM_ADDR = 0x1,
+    DW_FORM_BLOCK4 = 0x4,
+    DW_FORM_STRING = 0x8,
+    DW_FORM_DATA4 = 0x6,
+    DW_FORM_BLOCK = 0x9,
+    DW_FORM_DATA1 = 0xb,
+    DW_FORM_FLAG = 0xc,
+    DW_FORM_REF4 = 0x13
+  };
+
+  void WriteVariableAbbreviation(Writer* w,
+                                 int abbreviation_code,
+                                 bool has_value,
+                                 bool is_parameter) {
+    w->WriteULEB128(abbreviation_code);
+    w->WriteULEB128(is_parameter ? DW_TAG_FORMAL_PARAMETER : DW_TAG_VARIABLE);
+    w->Write<uint8_t>(DW_CHILDREN_NO);
+    w->WriteULEB128(DW_AT_NAME);
+    w->WriteULEB128(DW_FORM_STRING);
+    if (has_value) {
+      w->WriteULEB128(DW_AT_TYPE);
+      w->WriteULEB128(DW_FORM_REF4);
+      w->WriteULEB128(DW_AT_LOCATION);
+      w->WriteULEB128(DW_FORM_BLOCK4);
+    }
+    w->WriteULEB128(0);
+    w->WriteULEB128(0);
+  }
+
+  bool WriteBodyInternal(Writer* w) {
+    int current_abbreviation = 1;
+    bool extra_info = desc_->IsInfoAvailable();
+    ASSERT(desc_->IsLineInfoAvailable());
+    w->WriteULEB128(current_abbreviation++);
+    w->WriteULEB128(DW_TAG_COMPILE_UNIT);
+    w->Write<uint8_t>(extra_info ? DW_CHILDREN_YES : DW_CHILDREN_NO);
+    w->WriteULEB128(DW_AT_NAME);
+    w->WriteULEB128(DW_FORM_STRING);
+    w->WriteULEB128(DW_AT_LOW_PC);
+    w->WriteULEB128(DW_FORM_ADDR);
+    w->WriteULEB128(DW_AT_HIGH_PC);
+    w->WriteULEB128(DW_FORM_ADDR);
+    w->WriteULEB128(DW_AT_STMT_LIST);
+    w->WriteULEB128(DW_FORM_DATA4);
+    w->WriteULEB128(0);
+    w->WriteULEB128(0);
+
+    if (extra_info) {
+      Scope* scope = desc_->info()->scope();
+      int params = scope->num_parameters();
+      int slots = scope->num_stack_slots();
+      int context_slots = scope->ContextLocalCount();
+      // The real slot ID is internal_slots + context_slot_id.
+      int internal_slots = Context::MIN_CONTEXT_SLOTS;
+      int locals = scope->StackLocalCount();
+      // Total children is params + slots + context_slots + internal_slots +
+      // locals + 2 (__function and __context).
+
+      // The extra duplication below seems to be necessary to keep
+      // gdb from getting upset on OSX.
+      w->WriteULEB128(current_abbreviation++);  // Abbreviation code.
+      w->WriteULEB128(DW_TAG_SUBPROGRAM);
+      w->Write<uint8_t>(DW_CHILDREN_YES);
+      w->WriteULEB128(DW_AT_NAME);
+      w->WriteULEB128(DW_FORM_STRING);
+      w->WriteULEB128(DW_AT_LOW_PC);
+      w->WriteULEB128(DW_FORM_ADDR);
+      w->WriteULEB128(DW_AT_HIGH_PC);
+      w->WriteULEB128(DW_FORM_ADDR);
+      w->WriteULEB128(DW_AT_FRAME_BASE);
+      w->WriteULEB128(DW_FORM_BLOCK4);
+      w->WriteULEB128(0);
+      w->WriteULEB128(0);
+
+      w->WriteULEB128(current_abbreviation++);
+      w->WriteULEB128(DW_TAG_STRUCTURE_TYPE);
+      w->Write<uint8_t>(DW_CHILDREN_NO);
+      w->WriteULEB128(DW_AT_BYTE_SIZE);
+      w->WriteULEB128(DW_FORM_DATA1);
+      w->WriteULEB128(DW_AT_NAME);
+      w->WriteULEB128(DW_FORM_STRING);
+      w->WriteULEB128(0);
+      w->WriteULEB128(0);
+
+      for (int param = 0; param < params; ++param) {
+        WriteVariableAbbreviation(w, current_abbreviation++, true, true);
+      }
+
+      for (int slot = 0; slot < slots; ++slot) {
+        WriteVariableAbbreviation(w, current_abbreviation++, false, false);
+      }
+
+      for (int internal_slot = 0;
+           internal_slot < internal_slots;
+           ++internal_slot) {
+        WriteVariableAbbreviation(w, current_abbreviation++, false, false);
+      }
+
+      for (int context_slot = 0;
+           context_slot < context_slots;
+           ++context_slot) {
+        WriteVariableAbbreviation(w, current_abbreviation++, false, false);
+      }
+
+      for (int local = 0; local < locals; ++local) {
+        WriteVariableAbbreviation(w, current_abbreviation++, true, false);
+      }
+
+      // The function.
+      WriteVariableAbbreviation(w, current_abbreviation++, true, false);
+
+      // The context.
+      WriteVariableAbbreviation(w, current_abbreviation++, true, false);
+
+      w->WriteULEB128(0);  // Terminate the sibling list.
+    }
+
+    w->WriteULEB128(0);  // Terminate the table.
+    return true;
+  }
+
+ private:
+  CodeDescription* desc_;
+};
+
+
+class DebugLineSection : public DebugSection {
+ public:
+  explicit DebugLineSection(CodeDescription* desc)
+#ifdef __ELF
+      : ELFSection(".debug_line", TYPE_PROGBITS, 1),
+#else
+      : MachOSection("__debug_line",
+                     "__DWARF",
+                     1,
+                     MachOSection::S_REGULAR | MachOSection::S_ATTR_DEBUG),
+#endif
+        desc_(desc) { }
+
+  // DWARF2 standard, figure 34.
+  enum DWARF2Opcodes {
+    DW_LNS_COPY = 1,
+    DW_LNS_ADVANCE_PC = 2,
+    DW_LNS_ADVANCE_LINE = 3,
+    DW_LNS_SET_FILE = 4,
+    DW_LNS_SET_COLUMN = 5,
+    DW_LNS_NEGATE_STMT = 6
+  };
+
+  // DWARF2 standard, figure 35.
+  enum DWARF2ExtendedOpcode {
+    DW_LNE_END_SEQUENCE = 1,
+    DW_LNE_SET_ADDRESS = 2,
+    DW_LNE_DEFINE_FILE = 3
+  };
+
+  bool WriteBodyInternal(Writer* w) {
+    // Write prologue.
+    Writer::Slot<uint32_t> total_length = w->CreateSlotHere<uint32_t>();
+    uintptr_t start = w->position();
+
+    // Used for special opcodes
+    const int8_t line_base = 1;
+    const uint8_t line_range = 7;
+    const int8_t max_line_incr = (line_base + line_range - 1);
+    const uint8_t opcode_base = DW_LNS_NEGATE_STMT + 1;
+
+    w->Write<uint16_t>(2);  // Field version.
+    Writer::Slot<uint32_t> prologue_length = w->CreateSlotHere<uint32_t>();
+    uintptr_t prologue_start = w->position();
+    w->Write<uint8_t>(1);  // Field minimum_instruction_length.
+    w->Write<uint8_t>(1);  // Field default_is_stmt.
+    w->Write<int8_t>(line_base);  // Field line_base.
+    w->Write<uint8_t>(line_range);  // Field line_range.
+    w->Write<uint8_t>(opcode_base);  // Field opcode_base.
+    w->Write<uint8_t>(0);  // DW_LNS_COPY operands count.
+    w->Write<uint8_t>(1);  // DW_LNS_ADVANCE_PC operands count.
+    w->Write<uint8_t>(1);  // DW_LNS_ADVANCE_LINE operands count.
+    w->Write<uint8_t>(1);  // DW_LNS_SET_FILE operands count.
+    w->Write<uint8_t>(1);  // DW_LNS_SET_COLUMN operands count.
+    w->Write<uint8_t>(0);  // DW_LNS_NEGATE_STMT operands count.
+    w->Write<uint8_t>(0);  // Empty include_directories sequence.
+    w->WriteString(*desc_->GetFilename());  // File name.
+    w->WriteULEB128(0);  // Current directory.
+    w->WriteULEB128(0);  // Unknown modification time.
+    w->WriteULEB128(0);  // Unknown file size.
+    w->Write<uint8_t>(0);
+    prologue_length.set(static_cast<uint32_t>(w->position() - prologue_start));
+
+    WriteExtendedOpcode(w, DW_LNE_SET_ADDRESS, sizeof(intptr_t));
+    w->Write<intptr_t>(desc_->CodeStart());
+    w->Write<uint8_t>(DW_LNS_COPY);
+
+    intptr_t pc = 0;
+    intptr_t line = 1;
+    bool is_statement = true;
+
+    List<GDBJITLineInfo::PCInfo>* pc_info = desc_->lineinfo()->pc_info();
+    pc_info->Sort(&ComparePCInfo);
+
+    int pc_info_length = pc_info->length();
+    for (int i = 0; i < pc_info_length; i++) {
+      GDBJITLineInfo::PCInfo* info = &pc_info->at(i);
+      ASSERT(info->pc_ >= pc);
+
+      // Reduce bloating in the debug line table by removing duplicate line
+      // entries (per DWARF2 standard).
+      intptr_t  new_line = desc_->GetScriptLineNumber(info->pos_);
+      if (new_line == line) {
+        continue;
+      }
+
+      // Mark statement boundaries.  For a better debugging experience, mark
+      // the last pc address in the function as a statement (e.g. "}"), so that
+      // a user can see the result of the last line executed in the function,
+      // should control reach the end.
+      if ((i+1) == pc_info_length) {
+        if (!is_statement) {
+          w->Write<uint8_t>(DW_LNS_NEGATE_STMT);
+        }
+      } else if (is_statement != info->is_statement_) {
+        w->Write<uint8_t>(DW_LNS_NEGATE_STMT);
+        is_statement = !is_statement;
+      }
+
+      // Generate special opcodes, if possible.  This results in more compact
+      // debug line tables.  See the DWARF 2.0 standard to learn more about
+      // special opcodes.
+      uintptr_t pc_diff = info->pc_ - pc;
+      intptr_t line_diff = new_line - line;
+
+      // Compute special opcode (see DWARF 2.0 standard)
+      intptr_t special_opcode = (line_diff - line_base) +
+                                (line_range * pc_diff) + opcode_base;
+
+      // If special_opcode is less than or equal to 255, it can be used as a
+      // special opcode.  If line_diff is larger than the max line increment
+      // allowed for a special opcode, or if line_diff is less than the minimum
+      // line that can be added to the line register (i.e. line_base), then
+      // special_opcode can't be used.
+      if ((special_opcode >= opcode_base) && (special_opcode <= 255) &&
+          (line_diff <= max_line_incr) && (line_diff >= line_base)) {
+        w->Write<uint8_t>(special_opcode);
+      } else {
+        w->Write<uint8_t>(DW_LNS_ADVANCE_PC);
+        w->WriteSLEB128(pc_diff);
+        w->Write<uint8_t>(DW_LNS_ADVANCE_LINE);
+        w->WriteSLEB128(line_diff);
+        w->Write<uint8_t>(DW_LNS_COPY);
+      }
+
+      // Increment the pc and line operands.
+      pc += pc_diff;
+      line += line_diff;
+    }
+    // Advance the pc to the end of the routine, since the end sequence opcode
+    // requires this.
+    w->Write<uint8_t>(DW_LNS_ADVANCE_PC);
+    w->WriteSLEB128(desc_->CodeSize() - pc);
+    WriteExtendedOpcode(w, DW_LNE_END_SEQUENCE, 0);
+    total_length.set(static_cast<uint32_t>(w->position() - start));
+    return true;
+  }
+
+ private:
+  void WriteExtendedOpcode(Writer* w,
+                           DWARF2ExtendedOpcode op,
+                           size_t operands_size) {
+    w->Write<uint8_t>(0);
+    w->WriteULEB128(operands_size + 1);
+    w->Write<uint8_t>(op);
+  }
+
+  static int ComparePCInfo(const GDBJITLineInfo::PCInfo* a,
+                           const GDBJITLineInfo::PCInfo* b) {
+    if (a->pc_ == b->pc_) {
+      if (a->is_statement_ != b->is_statement_) {
+        return b->is_statement_ ? +1 : -1;
+      }
+      return 0;
+    } else if (a->pc_ > b->pc_) {
+      return +1;
+    } else {
+      return -1;
+    }
+  }
+
+  CodeDescription* desc_;
+};
+
+
+#if V8_TARGET_ARCH_X64
+
+class UnwindInfoSection : public DebugSection {
+ public:
+  explicit UnwindInfoSection(CodeDescription* desc);
+  virtual bool WriteBodyInternal(Writer* w);
+
+  int WriteCIE(Writer* w);
+  void WriteFDE(Writer* w, int);
+
+  void WriteFDEStateOnEntry(Writer* w);
+  void WriteFDEStateAfterRBPPush(Writer* w);
+  void WriteFDEStateAfterRBPSet(Writer* w);
+  void WriteFDEStateAfterRBPPop(Writer* w);
+
+  void WriteLength(Writer* w,
+                   Writer::Slot<uint32_t>* length_slot,
+                   int initial_position);
+
+ private:
+  CodeDescription* desc_;
+
+  // DWARF3 Specification, Table 7.23
+  enum CFIInstructions {
+    DW_CFA_ADVANCE_LOC = 0x40,
+    DW_CFA_OFFSET = 0x80,
+    DW_CFA_RESTORE = 0xC0,
+    DW_CFA_NOP = 0x00,
+    DW_CFA_SET_LOC = 0x01,
+    DW_CFA_ADVANCE_LOC1 = 0x02,
+    DW_CFA_ADVANCE_LOC2 = 0x03,
+    DW_CFA_ADVANCE_LOC4 = 0x04,
+    DW_CFA_OFFSET_EXTENDED = 0x05,
+    DW_CFA_RESTORE_EXTENDED = 0x06,
+    DW_CFA_UNDEFINED = 0x07,
+    DW_CFA_SAME_VALUE = 0x08,
+    DW_CFA_REGISTER = 0x09,
+    DW_CFA_REMEMBER_STATE = 0x0A,
+    DW_CFA_RESTORE_STATE = 0x0B,
+    DW_CFA_DEF_CFA = 0x0C,
+    DW_CFA_DEF_CFA_REGISTER = 0x0D,
+    DW_CFA_DEF_CFA_OFFSET = 0x0E,
+
+    DW_CFA_DEF_CFA_EXPRESSION = 0x0F,
+    DW_CFA_EXPRESSION = 0x10,
+    DW_CFA_OFFSET_EXTENDED_SF = 0x11,
+    DW_CFA_DEF_CFA_SF = 0x12,
+    DW_CFA_DEF_CFA_OFFSET_SF = 0x13,
+    DW_CFA_VAL_OFFSET = 0x14,
+    DW_CFA_VAL_OFFSET_SF = 0x15,
+    DW_CFA_VAL_EXPRESSION = 0x16
+  };
+
+  // System V ABI, AMD64 Supplement, Version 0.99.5, Figure 3.36
+  enum RegisterMapping {
+    // Only the relevant ones have been added to reduce clutter.
+    AMD64_RBP = 6,
+    AMD64_RSP = 7,
+    AMD64_RA = 16
+  };
+
+  enum CFIConstants {
+    CIE_ID = 0,
+    CIE_VERSION = 1,
+    CODE_ALIGN_FACTOR = 1,
+    DATA_ALIGN_FACTOR = 1,
+    RETURN_ADDRESS_REGISTER = AMD64_RA
+  };
+};
+
+
+void UnwindInfoSection::WriteLength(Writer* w,
+                                    Writer::Slot<uint32_t>* length_slot,
+                                    int initial_position) {
+  uint32_t align = (w->position() - initial_position) % kPointerSize;
+
+  if (align != 0) {
+    for (uint32_t i = 0; i < (kPointerSize - align); i++) {
+      w->Write<uint8_t>(DW_CFA_NOP);
+    }
+  }
+
+  ASSERT((w->position() - initial_position) % kPointerSize == 0);
+  length_slot->set(w->position() - initial_position);
+}
+
+
+UnwindInfoSection::UnwindInfoSection(CodeDescription* desc)
+#ifdef __ELF
+    : ELFSection(".eh_frame", TYPE_X86_64_UNWIND, 1),
+#else
+    : MachOSection("__eh_frame", "__TEXT", sizeof(uintptr_t),
+                   MachOSection::S_REGULAR),
+#endif
+      desc_(desc) { }
+
+int UnwindInfoSection::WriteCIE(Writer* w) {
+  Writer::Slot<uint32_t> cie_length_slot = w->CreateSlotHere<uint32_t>();
+  uint32_t cie_position = w->position();
+
+  // Write out the CIE header. Currently no 'common instructions' are
+  // emitted onto the CIE; every FDE has its own set of instructions.
+
+  w->Write<uint32_t>(CIE_ID);
+  w->Write<uint8_t>(CIE_VERSION);
+  w->Write<uint8_t>(0);  // Null augmentation string.
+  w->WriteSLEB128(CODE_ALIGN_FACTOR);
+  w->WriteSLEB128(DATA_ALIGN_FACTOR);
+  w->Write<uint8_t>(RETURN_ADDRESS_REGISTER);
+
+  WriteLength(w, &cie_length_slot, cie_position);
+
+  return cie_position;
+}
+
+
+void UnwindInfoSection::WriteFDE(Writer* w, int cie_position) {
+  // The only FDE for this function. The CFA is the current RBP.
+  Writer::Slot<uint32_t> fde_length_slot = w->CreateSlotHere<uint32_t>();
+  int fde_position = w->position();
+  w->Write<int32_t>(fde_position - cie_position + 4);
+
+  w->Write<uintptr_t>(desc_->CodeStart());
+  w->Write<uintptr_t>(desc_->CodeSize());
+
+  WriteFDEStateOnEntry(w);
+  WriteFDEStateAfterRBPPush(w);
+  WriteFDEStateAfterRBPSet(w);
+  WriteFDEStateAfterRBPPop(w);
+
+  WriteLength(w, &fde_length_slot, fde_position);
+}
+
+
+void UnwindInfoSection::WriteFDEStateOnEntry(Writer* w) {
+  // The first state, just after the control has been transferred to the the
+  // function.
+
+  // RBP for this function will be the value of RSP after pushing the RBP
+  // for the previous function. The previous RBP has not been pushed yet.
+  w->Write<uint8_t>(DW_CFA_DEF_CFA_SF);
+  w->WriteULEB128(AMD64_RSP);
+  w->WriteSLEB128(-kPointerSize);
+
+  // The RA is stored at location CFA + kCallerPCOffset. This is an invariant,
+  // and hence omitted from the next states.
+  w->Write<uint8_t>(DW_CFA_OFFSET_EXTENDED);
+  w->WriteULEB128(AMD64_RA);
+  w->WriteSLEB128(StandardFrameConstants::kCallerPCOffset);
+
+  // The RBP of the previous function is still in RBP.
+  w->Write<uint8_t>(DW_CFA_SAME_VALUE);
+  w->WriteULEB128(AMD64_RBP);
+
+  // Last location described by this entry.
+  w->Write<uint8_t>(DW_CFA_SET_LOC);
+  w->Write<uint64_t>(
+      desc_->GetStackStateStartAddress(CodeDescription::POST_RBP_PUSH));
+}
+
+
+void UnwindInfoSection::WriteFDEStateAfterRBPPush(Writer* w) {
+  // The second state, just after RBP has been pushed.
+
+  // RBP / CFA for this function is now the current RSP, so just set the
+  // offset from the previous rule (from -8) to 0.
+  w->Write<uint8_t>(DW_CFA_DEF_CFA_OFFSET);
+  w->WriteULEB128(0);
+
+  // The previous RBP is stored at CFA + kCallerFPOffset. This is an invariant
+  // in this and the next state, and hence omitted in the next state.
+  w->Write<uint8_t>(DW_CFA_OFFSET_EXTENDED);
+  w->WriteULEB128(AMD64_RBP);
+  w->WriteSLEB128(StandardFrameConstants::kCallerFPOffset);
+
+  // Last location described by this entry.
+  w->Write<uint8_t>(DW_CFA_SET_LOC);
+  w->Write<uint64_t>(
+      desc_->GetStackStateStartAddress(CodeDescription::POST_RBP_SET));
+}
+
+
+void UnwindInfoSection::WriteFDEStateAfterRBPSet(Writer* w) {
+  // The third state, after the RBP has been set.
+
+  // The CFA can now directly be set to RBP.
+  w->Write<uint8_t>(DW_CFA_DEF_CFA);
+  w->WriteULEB128(AMD64_RBP);
+  w->WriteULEB128(0);
+
+  // Last location described by this entry.
+  w->Write<uint8_t>(DW_CFA_SET_LOC);
+  w->Write<uint64_t>(
+      desc_->GetStackStateStartAddress(CodeDescription::POST_RBP_POP));
+}
+
+
+void UnwindInfoSection::WriteFDEStateAfterRBPPop(Writer* w) {
+  // The fourth (final) state. The RBP has been popped (just before issuing a
+  // return).
+
+  // The CFA can is now calculated in the same way as in the first state.
+  w->Write<uint8_t>(DW_CFA_DEF_CFA_SF);
+  w->WriteULEB128(AMD64_RSP);
+  w->WriteSLEB128(-kPointerSize);
+
+  // The RBP
+  w->Write<uint8_t>(DW_CFA_OFFSET_EXTENDED);
+  w->WriteULEB128(AMD64_RBP);
+  w->WriteSLEB128(StandardFrameConstants::kCallerFPOffset);
+
+  // Last location described by this entry.
+  w->Write<uint8_t>(DW_CFA_SET_LOC);
+  w->Write<uint64_t>(desc_->CodeEnd());
+}
+
+
+bool UnwindInfoSection::WriteBodyInternal(Writer* w) {
+  uint32_t cie_position = WriteCIE(w);
+  WriteFDE(w, cie_position);
+  return true;
+}
+
+
+#endif  // V8_TARGET_ARCH_X64
+
+static void CreateDWARFSections(CodeDescription* desc,
+                                Zone* zone,
+                                DebugObject* obj) {
+  if (desc->IsLineInfoAvailable()) {
+    obj->AddSection(new(zone) DebugInfoSection(desc));
+    obj->AddSection(new(zone) DebugAbbrevSection(desc));
+    obj->AddSection(new(zone) DebugLineSection(desc));
+  }
+#if V8_TARGET_ARCH_X64
+  obj->AddSection(new(zone) UnwindInfoSection(desc));
+#endif
+}
+
+
+// -------------------------------------------------------------------
+// Binary GDB JIT Interface as described in
+//   http://sourceware.org/gdb/onlinedocs/gdb/Declarations.html
+extern "C" {
+  typedef enum {
+    JIT_NOACTION = 0,
+    JIT_REGISTER_FN,
+    JIT_UNREGISTER_FN
+  } JITAction;
+
+  struct JITCodeEntry {
+    JITCodeEntry* next_;
+    JITCodeEntry* prev_;
+    Address symfile_addr_;
+    uint64_t symfile_size_;
+  };
+
+  struct JITDescriptor {
+    uint32_t version_;
+    uint32_t action_flag_;
+    JITCodeEntry* relevant_entry_;
+    JITCodeEntry* first_entry_;
+  };
+
+  // GDB will place breakpoint into this function.
+  // To prevent GCC from inlining or removing it we place noinline attribute
+  // and inline assembler statement inside.
+  void __attribute__((noinline)) __jit_debug_register_code() {
+    __asm__("");
+  }
+
+  // GDB will inspect contents of this descriptor.
+  // Static initialization is necessary to prevent GDB from seeing
+  // uninitialized descriptor.
+  JITDescriptor __jit_debug_descriptor = { 1, 0, 0, 0 };
+
+#ifdef OBJECT_PRINT
+  void __gdb_print_v8_object(MaybeObject* object) {
+    object->Print();
+    PrintF(stdout, "\n");
+  }
+#endif
+}
+
+
+static JITCodeEntry* CreateCodeEntry(Address symfile_addr,
+                                     uintptr_t symfile_size) {
+  JITCodeEntry* entry = static_cast<JITCodeEntry*>(
+      malloc(sizeof(JITCodeEntry) + symfile_size));
+
+  entry->symfile_addr_ = reinterpret_cast<Address>(entry + 1);
+  entry->symfile_size_ = symfile_size;
+  OS::MemCopy(entry->symfile_addr_, symfile_addr, symfile_size);
+
+  entry->prev_ = entry->next_ = NULL;
+
+  return entry;
+}
+
+
+static void DestroyCodeEntry(JITCodeEntry* entry) {
+  free(entry);
+}
+
+
+static void RegisterCodeEntry(JITCodeEntry* entry,
+                              bool dump_if_enabled,
+                              const char* name_hint) {
+#if defined(DEBUG) && !defined(WIN32)
+  static int file_num = 0;
+  if (FLAG_gdbjit_dump && dump_if_enabled) {
+    static const int kMaxFileNameSize = 64;
+    static const char* kElfFilePrefix = "/tmp/elfdump";
+    static const char* kObjFileExt = ".o";
+    char file_name[64];
+
+    OS::SNPrintF(Vector<char>(file_name, kMaxFileNameSize),
+                 "%s%s%d%s",
+                 kElfFilePrefix,
+                 (name_hint != NULL) ? name_hint : "",
+                 file_num++,
+                 kObjFileExt);
+    WriteBytes(file_name, entry->symfile_addr_, entry->symfile_size_);
+  }
+#endif
+
+  entry->next_ = __jit_debug_descriptor.first_entry_;
+  if (entry->next_ != NULL) entry->next_->prev_ = entry;
+  __jit_debug_descriptor.first_entry_ =
+      __jit_debug_descriptor.relevant_entry_ = entry;
+
+  __jit_debug_descriptor.action_flag_ = JIT_REGISTER_FN;
+  __jit_debug_register_code();
+}
+
+
+static void UnregisterCodeEntry(JITCodeEntry* entry) {
+  if (entry->prev_ != NULL) {
+    entry->prev_->next_ = entry->next_;
+  } else {
+    __jit_debug_descriptor.first_entry_ = entry->next_;
+  }
+
+  if (entry->next_ != NULL) {
+    entry->next_->prev_ = entry->prev_;
+  }
+
+  __jit_debug_descriptor.relevant_entry_ = entry;
+  __jit_debug_descriptor.action_flag_ = JIT_UNREGISTER_FN;
+  __jit_debug_register_code();
+}
+
+
+static JITCodeEntry* CreateELFObject(CodeDescription* desc, Isolate* isolate) {
+#ifdef __MACH_O
+  Zone zone(isolate);
+  MachO mach_o(&zone);
+  Writer w(&mach_o);
+
+  mach_o.AddSection(new(&zone) MachOTextSection(kCodeAlignment,
+                                                desc->CodeStart(),
+                                                desc->CodeSize()));
+
+  CreateDWARFSections(desc, &zone, &mach_o);
+
+  mach_o.Write(&w, desc->CodeStart(), desc->CodeSize());
+#else
+  Zone zone(isolate);
+  ELF elf(&zone);
+  Writer w(&elf);
+
+  int text_section_index = elf.AddSection(
+      new(&zone) FullHeaderELFSection(
+          ".text",
+          ELFSection::TYPE_NOBITS,
+          kCodeAlignment,
+          desc->CodeStart(),
+          0,
+          desc->CodeSize(),
+          ELFSection::FLAG_ALLOC | ELFSection::FLAG_EXEC));
+
+  CreateSymbolsTable(desc, &zone, &elf, text_section_index);
+
+  CreateDWARFSections(desc, &zone, &elf);
+
+  elf.Write(&w);
+#endif
+
+  return CreateCodeEntry(w.buffer(), w.position());
+}
+
+
+static bool SameCodeObjects(void* key1, void* key2) {
+  return key1 == key2;
+}
+
+
+static HashMap* GetEntries() {
+  static HashMap* entries = NULL;
+  if (entries == NULL) {
+    entries = new HashMap(&SameCodeObjects);
+  }
+  return entries;
+}
+
+
+static uint32_t HashForCodeObject(Code* code) {
+  static const uintptr_t kGoldenRatio = 2654435761u;
+  uintptr_t hash = reinterpret_cast<uintptr_t>(code->address());
+  return static_cast<uint32_t>((hash >> kCodeAlignmentBits) * kGoldenRatio);
+}
+
+
+static const intptr_t kLineInfoTag = 0x1;
+
+
+static bool IsLineInfoTagged(void* ptr) {
+  return 0 != (reinterpret_cast<intptr_t>(ptr) & kLineInfoTag);
+}
+
+
+static void* TagLineInfo(GDBJITLineInfo* ptr) {
+  return reinterpret_cast<void*>(
+      reinterpret_cast<intptr_t>(ptr) | kLineInfoTag);
+}
+
+
+static GDBJITLineInfo* UntagLineInfo(void* ptr) {
+  return reinterpret_cast<GDBJITLineInfo*>(
+      reinterpret_cast<intptr_t>(ptr) & ~kLineInfoTag);
+}
+
+
+void GDBJITInterface::AddCode(Handle<Name> name,
+                              Handle<Script> script,
+                              Handle<Code> code,
+                              CompilationInfo* info) {
+  if (!FLAG_gdbjit) return;
+
+  // Force initialization of line_ends array.
+  GetScriptLineNumber(script, 0);
+
+  if (!name.is_null() && name->IsString()) {
+    SmartArrayPointer<char> name_cstring =
+        Handle<String>::cast(name)->ToCString(DISALLOW_NULLS);
+    AddCode(*name_cstring, *code, GDBJITInterface::FUNCTION, *script, info);
+  } else {
+    AddCode("", *code, GDBJITInterface::FUNCTION, *script, info);
+  }
+}
+
+
+static void AddUnwindInfo(CodeDescription* desc) {
+#if V8_TARGET_ARCH_X64
+  if (desc->tag() == GDBJITInterface::FUNCTION) {
+    // To avoid propagating unwinding information through
+    // compilation pipeline we use an approximation.
+    // For most use cases this should not affect usability.
+    static const int kFramePointerPushOffset = 1;
+    static const int kFramePointerSetOffset = 4;
+    static const int kFramePointerPopOffset = -3;
+
+    uintptr_t frame_pointer_push_address =
+        desc->CodeStart() + kFramePointerPushOffset;
+
+    uintptr_t frame_pointer_set_address =
+        desc->CodeStart() + kFramePointerSetOffset;
+
+    uintptr_t frame_pointer_pop_address =
+        desc->CodeEnd() + kFramePointerPopOffset;
+
+    desc->SetStackStateStartAddress(CodeDescription::POST_RBP_PUSH,
+                                    frame_pointer_push_address);
+    desc->SetStackStateStartAddress(CodeDescription::POST_RBP_SET,
+                                    frame_pointer_set_address);
+    desc->SetStackStateStartAddress(CodeDescription::POST_RBP_POP,
+                                    frame_pointer_pop_address);
+  } else {
+    desc->SetStackStateStartAddress(CodeDescription::POST_RBP_PUSH,
+                                    desc->CodeStart());
+    desc->SetStackStateStartAddress(CodeDescription::POST_RBP_SET,
+                                    desc->CodeStart());
+    desc->SetStackStateStartAddress(CodeDescription::POST_RBP_POP,
+                                    desc->CodeEnd());
+  }
+#endif  // V8_TARGET_ARCH_X64
+}
+
+
+static LazyMutex mutex = LAZY_MUTEX_INITIALIZER;
+
+
+void GDBJITInterface::AddCode(const char* name,
+                              Code* code,
+                              GDBJITInterface::CodeTag tag,
+                              Script* script,
+                              CompilationInfo* info) {
+  if (!FLAG_gdbjit) return;
+
+  ScopedLock lock(mutex.Pointer());
+  DisallowHeapAllocation no_gc;
+
+  HashMap::Entry* e = GetEntries()->Lookup(code, HashForCodeObject(code), true);
+  if (e->value != NULL && !IsLineInfoTagged(e->value)) return;
+
+  GDBJITLineInfo* lineinfo = UntagLineInfo(e->value);
+  CodeDescription code_desc(name,
+                            code,
+                            script != NULL ? Handle<Script>(script)
+                                           : Handle<Script>(),
+                            lineinfo,
+                            tag,
+                            info);
+
+  if (!FLAG_gdbjit_full && !code_desc.IsLineInfoAvailable()) {
+    delete lineinfo;
+    GetEntries()->Remove(code, HashForCodeObject(code));
+    return;
+  }
+
+  AddUnwindInfo(&code_desc);
+  Isolate* isolate = code->GetIsolate();
+  JITCodeEntry* entry = CreateELFObject(&code_desc, isolate);
+  ASSERT(!IsLineInfoTagged(entry));
+
+  delete lineinfo;
+  e->value = entry;
+
+  const char* name_hint = NULL;
+  bool should_dump = false;
+  if (FLAG_gdbjit_dump) {
+    if (strlen(FLAG_gdbjit_dump_filter) == 0) {
+      name_hint = name;
+      should_dump = true;
+    } else if (name != NULL) {
+      name_hint = strstr(name, FLAG_gdbjit_dump_filter);
+      should_dump = (name_hint != NULL);
+    }
+  }
+  RegisterCodeEntry(entry, should_dump, name_hint);
+}
+
+
+void GDBJITInterface::AddCode(GDBJITInterface::CodeTag tag,
+                              const char* name,
+                              Code* code) {
+  if (!FLAG_gdbjit) return;
+
+  EmbeddedVector<char, 256> buffer;
+  StringBuilder builder(buffer.start(), buffer.length());
+
+  builder.AddString(Tag2String(tag));
+  if ((name != NULL) && (*name != '\0')) {
+    builder.AddString(": ");
+    builder.AddString(name);
+  } else {
+    builder.AddFormatted(": code object %p", static_cast<void*>(code));
+  }
+
+  AddCode(builder.Finalize(), code, tag, NULL, NULL);
+}
+
+
+void GDBJITInterface::AddCode(GDBJITInterface::CodeTag tag,
+                              Name* name,
+                              Code* code) {
+  if (!FLAG_gdbjit) return;
+  if (name != NULL && name->IsString()) {
+    AddCode(tag, *String::cast(name)->ToCString(DISALLOW_NULLS), code);
+  } else {
+    AddCode(tag, "", code);
+  }
+}
+
+
+void GDBJITInterface::AddCode(GDBJITInterface::CodeTag tag, Code* code) {
+  if (!FLAG_gdbjit) return;
+
+  AddCode(tag, "", code);
+}
+
+
+void GDBJITInterface::RemoveCode(Code* code) {
+  if (!FLAG_gdbjit) return;
+
+  ScopedLock lock(mutex.Pointer());
+  HashMap::Entry* e = GetEntries()->Lookup(code,
+                                           HashForCodeObject(code),
+                                           false);
+  if (e == NULL) return;
+
+  if (IsLineInfoTagged(e->value)) {
+    delete UntagLineInfo(e->value);
+  } else {
+    JITCodeEntry* entry = static_cast<JITCodeEntry*>(e->value);
+    UnregisterCodeEntry(entry);
+    DestroyCodeEntry(entry);
+  }
+  e->value = NULL;
+  GetEntries()->Remove(code, HashForCodeObject(code));
+}
+
+
+void GDBJITInterface::RemoveCodeRange(Address start, Address end) {
+  HashMap* entries = GetEntries();
+  Zone zone(Isolate::Current());
+  ZoneList<Code*> dead_codes(1, &zone);
+
+  for (HashMap::Entry* e = entries->Start(); e != NULL; e = entries->Next(e)) {
+    Code* code = reinterpret_cast<Code*>(e->key);
+    if (code->address() >= start && code->address() < end) {
+      dead_codes.Add(code, &zone);
+    }
+  }
+
+  for (int i = 0; i < dead_codes.length(); i++) {
+    RemoveCode(dead_codes.at(i));
+  }
+}
+
+
+void GDBJITInterface::RegisterDetailedLineInfo(Code* code,
+                                               GDBJITLineInfo* line_info) {
+  ScopedLock lock(mutex.Pointer());
+  ASSERT(!IsLineInfoTagged(line_info));
+  HashMap::Entry* e = GetEntries()->Lookup(code, HashForCodeObject(code), true);
+  ASSERT(e->value == NULL);
+  e->value = TagLineInfo(line_info);
+}
+
+
+} }  // namespace v8::internal
+#endif