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// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <cinttypes>
#if !defined(V8_OS_STARBOARD)
#include <cstdio>
#include <cstring>
#include "src/common/globals.h"
#include "src/snapshot/embedded/embedded-data.h"
#include "src/snapshot/embedded/platform-embedded-file-writer-base.h"
#if defined(V8_OS_WIN_X64)
#include "src/diagnostics/unwinding-info-win64.h"
namespace v8 {
namespace internal {
static constexpr char kDefaultEmbeddedVariant[] = "Default";
// Detailed source-code information about builtins can only be obtained by
// registration on the isolate during compilation.
class EmbeddedFileWriterInterface {
// We maintain a database of filenames to synthetic IDs.
virtual int LookupOrAddExternallyCompiledFilename(const char* filename) = 0;
virtual const char* GetExternallyCompiledFilename(int index) const = 0;
virtual int GetExternallyCompiledFilenameCount() const = 0;
// The isolate will call the method below just prior to replacing the
// compiled builtin Code objects with trampolines.
virtual void PrepareBuiltinSourcePositionMap(Builtins* builtins) = 0;
#if defined(V8_OS_WIN_X64)
virtual void SetBuiltinUnwindData(
int builtin_index,
const win64_unwindinfo::BuiltinUnwindInfo& unwinding_info) = 0;
// Generates the embedded.S file which is later compiled into the final v8
// binary. Its contents are exported through two symbols:
// v8_<variant>_embedded_blob_ (intptr_t):
// a pointer to the start of the embedded blob.
// v8_<variant>_embedded_blob_size_ (uint32_t):
// size of the embedded blob in bytes.
// The variant is usually "Default" but can be modified in multisnapshot builds.
class EmbeddedFileWriter : public EmbeddedFileWriterInterface {
int LookupOrAddExternallyCompiledFilename(const char* filename) override;
const char* GetExternallyCompiledFilename(int fileid) const override;
int GetExternallyCompiledFilenameCount() const override;
void PrepareBuiltinSourcePositionMap(Builtins* builtins) override;
#if defined(V8_OS_WIN_X64)
void SetBuiltinUnwindData(
int builtin_index,
const win64_unwindinfo::BuiltinUnwindInfo& unwinding_info) override {
DCHECK_LT(builtin_index, Builtins::builtin_count);
unwind_infos_[builtin_index] = unwinding_info;
void SetEmbeddedFile(const char* embedded_src_path) {
embedded_src_path_ = embedded_src_path;
void SetEmbeddedVariant(const char* embedded_variant) {
if (embedded_variant == nullptr) return;
embedded_variant_ = embedded_variant;
void SetTargetArch(const char* target_arch) { target_arch_ = target_arch; }
void SetTargetOs(const char* target_os) { target_os_ = target_os; }
void WriteEmbedded(const i::EmbeddedData* blob) const {
void MaybeWriteEmbeddedFile(const i::EmbeddedData* blob) const {
if (embedded_src_path_ == nullptr) return;
FILE* fp = GetFileDescriptorOrDie(embedded_src_path_);
std::unique_ptr<PlatformEmbeddedFileWriterBase> writer =
NewPlatformEmbeddedFileWriter(target_arch_, target_os_);
WriteMetadataSection(writer.get(), blob);
WriteInstructionStreams(writer.get(), blob);
WriteFileEpilogue(writer.get(), blob);
static FILE* GetFileDescriptorOrDie(const char* filename) {
FILE* fp = v8::base::OS::FOpen(filename, "wb");
if (fp == nullptr) {
i::PrintF("Unable to open file \"%s\" for writing.\n", filename);
return fp;
void WriteFilePrologue(PlatformEmbeddedFileWriterBase* w) const {
w->Comment("Autogenerated file. Do not edit.");
void WriteExternalFilenames(PlatformEmbeddedFileWriterBase* w) const {
"Source positions in the embedded blob refer to filenames by id.");
w->Comment("Assembly directives here map the id to a filename.");
// Write external filenames.
int size = static_cast<int>(external_filenames_by_index_.size());
for (int i = 0; i < size; i++) {
// Fairly arbitrary but should fit all symbol names.
static constexpr int kTemporaryStringLength = 256;
std::string EmbeddedBlobDataSymbol() const {
i::EmbeddedVector<char, kTemporaryStringLength> embedded_blob_data_symbol;
i::SNPrintF(embedded_blob_data_symbol, "v8_%s_embedded_blob_data_",
return std::string{embedded_blob_data_symbol.begin()};
void WriteMetadataSection(PlatformEmbeddedFileWriterBase* w,
const i::EmbeddedData* blob) const {
w->Comment("The embedded blob starts here. Metadata comes first, followed");
w->Comment("by builtin instruction streams.");
WriteBinaryContentsAsInlineAssembly(w, blob->data(),
void WriteBuiltin(PlatformEmbeddedFileWriterBase* w,
const i::EmbeddedData* blob, const int builtin_id) const;
void WriteInstructionStreams(PlatformEmbeddedFileWriterBase* w,
const i::EmbeddedData* blob) const {
for (int i = 0; i < i::Builtins::builtin_count; i++) {
if (!blob->ContainsBuiltin(i)) continue;
WriteBuiltin(w, blob, i);
void WriteFileEpilogue(PlatformEmbeddedFileWriterBase* w,
const i::EmbeddedData* blob) const;
#if defined(V8_OS_WIN_X64)
std::string BuiltinsUnwindInfoLabel() const;
void WriteUnwindInfo(PlatformEmbeddedFileWriterBase* w,
const i::EmbeddedData* blob) const;
void WriteUnwindInfoEntry(PlatformEmbeddedFileWriterBase* w,
uint64_t rva_start, uint64_t rva_end) const;
static void WriteBinaryContentsAsInlineAssembly(
PlatformEmbeddedFileWriterBase* w, const uint8_t* data, uint32_t size);
// In assembly directives, filename ids need to begin with 1.
static constexpr int kFirstExternalFilenameId = 1;
static int ExternalFilenameIndexToId(int index) {
return kFirstExternalFilenameId + index;
static int ExternalFilenameIdToIndex(int id) {
return id - kFirstExternalFilenameId;
std::vector<byte> source_positions_[Builtins::builtin_count];
#if defined(V8_OS_WIN_X64)
win64_unwindinfo::BuiltinUnwindInfo unwind_infos_[Builtins::builtin_count];
std::map<const char*, int> external_filenames_;
std::vector<const char*> external_filenames_by_index_;
// The file to generate or nullptr.
const char* embedded_src_path_ = nullptr;
// The variant is only used in multi-snapshot builds and otherwise set to
// "Default".
const char* embedded_variant_ = kDefaultEmbeddedVariant;
// {target_arch} and {target_os} control the generated assembly format. Note
// these may differ from both host- and target-platforms specified through
// e.g. V8_OS_* and V8_TARGET_ARCH_* defines.
const char* target_arch_ = nullptr;
const char* target_os_ = nullptr;
} // namespace internal
} // namespace v8