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dart / sdk / 1fbff78e68f9572de56e55ef36b84e942f9594ce / . / runtime / vm / image_snapshot.cc
blob: 9093c741b721203092b30a508062587287a043eb [file] [log] [blame]
// Copyright (c) 2017, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/image_snapshot.h"
#include "include/dart_api.h"
#include "platform/assert.h"
#include "platform/elf.h"
#include "vm/bss_relocs.h"
#include "vm/class_id.h"
#include "vm/compiler/runtime_api.h"
#include "vm/dwarf.h"
#include "vm/elf.h"
#include "vm/hash.h"
#include "vm/hash_map.h"
#include "vm/heap/heap.h"
#include "vm/instructions.h"
#include "vm/json_writer.h"
#include "vm/object.h"
#include "vm/object_store.h"
#include "vm/program_visitor.h"
#include "vm/stub_code.h"
#include "vm/timeline.h"
#include "vm/type_testing_stubs.h"
#include "vm/zone_text_buffer.h"
#if !defined(DART_PRECOMPILED_RUNTIME)
#include "vm/compiler/backend/code_statistics.h"
#endif // !defined(DART_PRECOMPILED_RUNTIME)
namespace dart {
#if defined(DART_PRECOMPILER)
DEFINE_FLAG(bool,
print_instruction_stats,
false,
"Print instruction statistics");
DEFINE_FLAG(charp,
print_instructions_sizes_to,
nullptr,
"Print sizes of all instruction objects to the given file");
#endif
const UntaggedInstructionsSection* Image::ExtraInfo(const uword raw_memory,
const uword size) {
#if defined(DART_PRECOMPILED_RUNTIME)
auto const raw_value =
FieldValue(raw_memory, HeaderField::InstructionsSectionOffset);
if (raw_value != kNoInstructionsSection) {
ASSERT(raw_value >= kHeaderSize);
ASSERT(raw_value <= size - InstructionsSection::HeaderSize());
auto const layout = reinterpret_cast<const UntaggedInstructionsSection*>(
raw_memory + raw_value);
// The instructions section is likely non-empty in bare instructions mode
// (unless splitting into multiple outputs and there are no Code objects
// in this particular output), but is guaranteed empty otherwise (the
// instructions follow the InstructionsSection object instead).
ASSERT(raw_value <=
size - InstructionsSection::InstanceSize(layout->payload_length_));
return layout;
}
#endif
return nullptr;
}
uword* Image::bss() const {
#if defined(DART_PRECOMPILED_RUNTIME)
ASSERT(extra_info_ != nullptr);
// There should always be a non-zero BSS offset.
ASSERT(extra_info_->bss_offset_ != 0);
// Returning a non-const uword* is safe because we're translating from
// the start of the instructions (read-only) to the start of the BSS
// (read-write).
return reinterpret_cast<uword*>(raw_memory_ + extra_info_->bss_offset_);
#else
return nullptr;
#endif
}
uword Image::instructions_relocated_address() const {
#if defined(DART_PRECOMPILED_RUNTIME)
ASSERT(extra_info_ != nullptr);
// For assembly snapshots, we need to retrieve this from the initialized BSS.
const uword address =
compiled_to_elf() ? extra_info_->instructions_relocated_address_
: bss()[BSS::RelocationIndex(
BSS::Relocation::InstructionsRelocatedAddress)];
ASSERT(address != kNoRelocatedAddress);
return address;
#else
return kNoRelocatedAddress;
#endif
}
const uint8_t* Image::build_id() const {
#if defined(DART_PRECOMPILED_RUNTIME)
ASSERT(extra_info_ != nullptr);
if (extra_info_->build_id_offset_ != kNoBuildId) {
auto const note = reinterpret_cast<elf::Note*>(
raw_memory_ + extra_info_->build_id_offset_);
return note->data + note->name_size;
}
#endif
return nullptr;
}
intptr_t Image::build_id_length() const {
#if defined(DART_PRECOMPILED_RUNTIME)
ASSERT(extra_info_ != nullptr);
if (extra_info_->build_id_offset_ != kNoBuildId) {
auto const note = reinterpret_cast<elf::Note*>(
raw_memory_ + extra_info_->build_id_offset_);
return note->description_size;
}
#endif
return 0;
}
bool Image::compiled_to_elf() const {
#if defined(DART_PRECOMPILED_RUNTIME)
ASSERT(extra_info_ != nullptr);
// Since assembly snapshots can't set up this field correctly (instead,
// it's initialized in BSS at snapshot load time), we use it to detect
// direct-to-ELF snapshots.
return extra_info_->instructions_relocated_address_ != kNoRelocatedAddress;
#else
return false;
#endif
}
uword ObjectOffsetTrait::Hash(Key key) {
ObjectPtr obj = key;
ASSERT(!obj->IsSmi());
uword body = UntaggedObject::ToAddr(obj) + sizeof(UntaggedObject);
uword end = UntaggedObject::ToAddr(obj) + obj->untag()->HeapSize();
uint32_t hash = obj->GetClassId();
// Don't include the header. Objects in the image are pre-marked, but objects
// in the current isolate are not.
for (uword cursor = body; cursor < end; cursor += sizeof(uint32_t)) {
hash = CombineHashes(hash, *reinterpret_cast<uint32_t*>(cursor));
}
return FinalizeHash(hash, 30);
}
bool ObjectOffsetTrait::IsKeyEqual(Pair pair, Key key) {
ObjectPtr a = pair.object;
ObjectPtr b = key;
ASSERT(!a->IsSmi());
ASSERT(!b->IsSmi());
if (a->GetClassId() != b->GetClassId()) {
return false;
}
intptr_t heap_size = a->untag()->HeapSize();
if (b->untag()->HeapSize() != heap_size) {
return false;
}
// Don't include the header. Objects in the image are pre-marked, but objects
// in the current isolate are not.
uword body_a = UntaggedObject::ToAddr(a) + sizeof(UntaggedObject);
uword body_b = UntaggedObject::ToAddr(b) + sizeof(UntaggedObject);
uword body_size = heap_size - sizeof(UntaggedObject);
return 0 == memcmp(reinterpret_cast<const void*>(body_a),
reinterpret_cast<const void*>(body_b), body_size);
}
#if !defined(DART_PRECOMPILED_RUNTIME)
#if defined(DART_PRECOMPILER)
ImageWriter::ImageWriter(Thread* t,
bool generates_assembly,
const Trie<const char>* deobfuscation_trie)
#else
ImageWriter::ImageWriter(Thread* t, bool generates_assembly)
#endif
: thread_(ASSERT_NOTNULL(t)),
zone_(t->zone()),
next_data_offset_(0),
next_text_offset_(0),
objects_(),
instructions_(),
#if defined(DART_PRECOMPILER)
namer_(t->zone(),
deobfuscation_trie,
/*for_assembly=*/generates_assembly),
#endif
image_type_(TagObjectTypeAsReadOnly(zone_, "Image")),
instructions_section_type_(
TagObjectTypeAsReadOnly(zone_, "InstructionsSection")),
instructions_type_(TagObjectTypeAsReadOnly(zone_, "Instructions")),
trampoline_type_(TagObjectTypeAsReadOnly(zone_, "Trampoline")) {
ResetOffsets();
}
void ImageWriter::PrepareForSerialization(
GrowableArray<ImageWriterCommand>* commands) {
if (commands != nullptr) {
const intptr_t initial_offset = next_text_offset_;
for (auto& inst : *commands) {
ASSERT((initial_offset + inst.expected_offset) == next_text_offset_);
switch (inst.op) {
case ImageWriterCommand::InsertInstructionOfCode: {
Heap* const heap = thread_->heap();
CodePtr code = inst.insert_instruction_of_code.code;
InstructionsPtr instructions = Code::InstructionsOf(code);
const intptr_t offset = next_text_offset_;
instructions_.Add(InstructionsData(instructions, code, offset));
next_text_offset_ += SizeInSnapshot(instructions);
ASSERT(heap->GetObjectId(instructions) == 0);
heap->SetObjectId(instructions, offset);
break;
}
case ImageWriterCommand::InsertBytesOfTrampoline: {
auto trampoline_bytes = inst.insert_trampoline_bytes.buffer;
auto trampoline_length = inst.insert_trampoline_bytes.buffer_length;
const intptr_t offset = next_text_offset_;
instructions_.Add(
InstructionsData(trampoline_bytes, trampoline_length, offset));
next_text_offset_ += trampoline_length;
break;
}
default:
UNREACHABLE();
}
}
}
}
int32_t ImageWriter::GetTextOffsetFor(InstructionsPtr instructions,
CodePtr code) {
Heap* const heap = thread_->heap();
intptr_t offset = heap->GetObjectId(instructions);
if (offset != 0) {
return offset;
}
offset = next_text_offset_;
heap->SetObjectId(instructions, offset);
next_text_offset_ += SizeInSnapshot(instructions);
instructions_.Add(InstructionsData(instructions, code, offset));
ASSERT(offset != 0);
return offset;
}
intptr_t ImageWriter::SizeInSnapshotForBytes(intptr_t length) {
// We are just going to write it out as a string.
return compiler::target::String::InstanceSize(
length * OneByteString::kBytesPerElement);
}
intptr_t ImageWriter::SizeInSnapshot(ObjectPtr raw_object) {
const classid_t cid = raw_object->GetClassId();
switch (cid) {
case kCompressedStackMapsCid: {
auto raw_maps = CompressedStackMaps::RawCast(raw_object);
return compiler::target::CompressedStackMaps::InstanceSize(
CompressedStackMaps::PayloadSizeOf(raw_maps));
}
case kCodeSourceMapCid: {
auto raw_map = CodeSourceMap::RawCast(raw_object);
return compiler::target::CodeSourceMap::InstanceSize(
raw_map->untag()->length_);
}
case kPcDescriptorsCid: {
auto raw_desc = PcDescriptors::RawCast(raw_object);
return compiler::target::PcDescriptors::InstanceSize(
raw_desc->untag()->length_);
}
case kInstructionsCid: {
auto raw_insns = Instructions::RawCast(raw_object);
return compiler::target::Instructions::InstanceSize(
Instructions::Size(raw_insns));
}
case kOneByteStringCid: {
auto raw_str = String::RawCast(raw_object);
return compiler::target::String::InstanceSize(
String::LengthOf(raw_str) * OneByteString::kBytesPerElement);
}
case kTwoByteStringCid: {
auto raw_str = String::RawCast(raw_object);
return compiler::target::String::InstanceSize(
String::LengthOf(raw_str) * TwoByteString::kBytesPerElement);
}
default: {
const Class& clazz = Class::Handle(Object::Handle(raw_object).clazz());
FATAL("Unsupported class %s in rodata section.\n", clazz.ToCString());
return 0;
}
}
}
#if defined(SNAPSHOT_BACKTRACE)
uint32_t ImageWriter::GetDataOffsetFor(ObjectPtr raw_object,
ObjectPtr raw_parent) {
#else
uint32_t ImageWriter::GetDataOffsetFor(ObjectPtr raw_object) {
#endif
const intptr_t snap_size = SizeInSnapshot(raw_object);
const intptr_t offset = next_data_offset_;
next_data_offset_ += snap_size;
#if defined(SNAPSHOT_BACKTRACE)
objects_.Add(ObjectData(raw_object, raw_parent));
#else
objects_.Add(ObjectData(raw_object));
#endif
return offset;
}
uint32_t ImageWriter::AddBytesToData(uint8_t* bytes, intptr_t length) {
const intptr_t snap_size = SizeInSnapshotForBytes(length);
const intptr_t offset = next_data_offset_;
next_data_offset_ += snap_size;
objects_.Add(ObjectData(bytes, length));
return offset;
}
intptr_t ImageWriter::GetTextObjectCount() const {
return instructions_.length();
}
void ImageWriter::GetTrampolineInfo(intptr_t* count, intptr_t* size) const {
ASSERT(count != nullptr && size != nullptr);
*count = 0;
*size = 0;
for (auto const& data : instructions_) {
if (data.trampoline_length != 0) {
*count += 1;
*size += data.trampoline_length;
}
}
}
// Returns nullptr if there is no profile writer.
const char* ImageWriter::ObjectTypeForProfile(const Object& object) const {
if (profile_writer_ == nullptr) return nullptr;
ASSERT(IsROSpace());
REUSABLE_CLASS_HANDLESCOPE(thread_);
REUSABLE_STRING_HANDLESCOPE(thread_);
Class& klass = thread_->ClassHandle();
String& name = thread_->StringHandle();
klass = object.clazz();
name = klass.UserVisibleName();
auto const name_str = name.ToCString();
return TagObjectTypeAsReadOnly(zone_, name_str);
}
const char* ImageWriter::TagObjectTypeAsReadOnly(Zone* zone, const char* type) {
ASSERT(zone != nullptr && type != nullptr);
return OS::SCreate(zone, "(RO) %s", type);
}
#if defined(DART_PRECOMPILER)
void ImageWriter::DumpInstructionStats() {
std::unique_ptr<CombinedCodeStatistics> instruction_stats(
new CombinedCodeStatistics());
for (intptr_t i = 0; i < instructions_.length(); i++) {
auto& data = instructions_[i];
CodeStatistics* stats = data.insns_->stats();
if (stats != nullptr) {
stats->AppendTo(instruction_stats.get());
}
}
instruction_stats->DumpStatistics();
}
void ImageWriter::DumpInstructionsSizes() {
auto& cls = Class::Handle(zone_);
auto& lib = Library::Handle(zone_);
auto& owner = Object::Handle(zone_);
auto& url = String::Handle(zone_);
auto& name = String::Handle(zone_);
intptr_t trampolines_total_size = 0;
JSONWriter js;
js.OpenArray();
for (intptr_t i = 0; i < instructions_.length(); i++) {
auto& data = instructions_[i];
const bool is_trampoline = data.code_ == nullptr;
if (is_trampoline) {
trampolines_total_size += data.trampoline_length;
continue;
}
owner = WeakSerializationReference::Unwrap(data.code_->owner());
js.OpenObject();
if (owner.IsFunction()) {
cls = Function::Cast(owner).Owner();
name = cls.ScrubbedName();
lib = cls.library();
url = lib.url();
js.PrintPropertyStr("l", url);
js.PrintPropertyStr("c", name);
} else if (owner.IsClass()) {
cls ^= owner.ptr();
name = cls.ScrubbedName();
lib = cls.library();
url = lib.url();
js.PrintPropertyStr("l", url);
js.PrintPropertyStr("c", name);
}
js.PrintProperty("n",
data.code_->QualifiedName(
NameFormattingParams::DisambiguatedWithoutClassName(
Object::kInternalName)));
js.PrintProperty("s", SizeInSnapshot(data.insns_->ptr()));
js.CloseObject();
}
if (trampolines_total_size != 0) {
js.OpenObject();
js.PrintProperty("n", "[Stub] Trampoline");
js.PrintProperty("s", trampolines_total_size);
js.CloseObject();
}
js.CloseArray();
auto file_open = Dart::file_open_callback();
auto file_write = Dart::file_write_callback();
auto file_close = Dart::file_close_callback();
if ((file_open == nullptr) || (file_write == nullptr) ||
(file_close == nullptr)) {
OS::PrintErr("warning: Could not access file callbacks.");
return;
}
const char* filename = FLAG_print_instructions_sizes_to;
void* file = file_open(filename, /*write=*/true);
if (file == nullptr) {
OS::PrintErr("warning: Failed to write instruction sizes: %s\n", filename);
return;
}
char* output = nullptr;
intptr_t output_length = 0;
js.Steal(&output, &output_length);
file_write(output, output_length, file);
free(output);
file_close(file);
}
void ImageWriter::DumpStatistics() {
if (FLAG_print_instruction_stats) {
DumpInstructionStats();
}
if (FLAG_print_instructions_sizes_to != nullptr) {
DumpInstructionsSizes();
}
}
#endif
void ImageWriter::Write(NonStreamingWriteStream* clustered_stream, bool vm) {
Heap* heap = thread_->heap();
TIMELINE_DURATION(thread_, Isolate, "WriteInstructions");
// Handlify collected raw pointers as building the names below
// will allocate on the Dart heap.
for (intptr_t i = 0; i < instructions_.length(); i++) {
InstructionsData& data = instructions_[i];
const bool is_trampoline = data.trampoline_bytes != nullptr;
if (is_trampoline) continue;
data.insns_ = &Instructions::Handle(zone_, data.raw_insns_);
ASSERT(data.raw_code_ != nullptr);
data.code_ = &Code::Handle(zone_, data.raw_code_);
// Reset object id as an isolate snapshot after a VM snapshot will not use
// the VM snapshot's text image.
heap->SetObjectId(data.insns_->ptr(), 0);
}
for (auto& data : objects_) {
if (data.is_object()) {
data.obj = &Object::Handle(zone_, data.raw_obj);
#if defined(SNAPSHOT_BACKTRACE)
data.parent = &Object::Handle(zone_, data.raw_parent);
#endif
}
}
// Once we have everything handlified we are going to do convert raw bytes
// to string objects. String is used for simplicity as a bit container,
// can't use TypedData because it has an internal pointer (data_) field.
for (auto& data : objects_) {
if (!data.is_object()) {
const auto bytes = data.bytes;
data.obj = &Object::Handle(
zone_, OneByteString::New(bytes.buf, bytes.length, Heap::kOld));
#if defined(SNAPSHOT_BACKTRACE)
data.parent = &Object::null_object();
#endif
data.set_is_object(true);
String::Cast(*data.obj).Hash();
free(bytes.buf);
}
}
// Needs to happen before WriteText, as we add information about the
// BSSsection in the text section as an initial InstructionsSection object.
WriteBss(vm);
offset_space_ = vm ? IdSpace::kVmText : IdSpace::kIsolateText;
WriteText(vm);
// Append the direct-mapped RO data objects after the clustered snapshot
// and then for ELF and assembly outputs, add appropriate sections with
// that combined data.
offset_space_ = vm ? IdSpace::kVmData : IdSpace::kIsolateData;
WriteROData(clustered_stream, vm);
}
void ImageWriter::WriteROData(NonStreamingWriteStream* stream, bool vm) {
ASSERT(Utils::IsAligned(stream->Position(), kRODataAlignment));
// Heap page starts here.
intptr_t section_start = stream->Position();
stream->WriteWord(next_data_offset_); // Data length.
stream->WriteWord(Image::kNoInstructionsSection);
// Zero values for the rest of the Image object header bytes.
stream->Align(Image::kHeaderSize);
ASSERT_EQUAL(stream->Position() - section_start, Image::kHeaderSize);
#if defined(DART_PRECOMPILER)
if (profile_writer_ != nullptr) {
// Attribute the Image header to the artificial root.
profile_writer_->AttributeBytesTo(
V8SnapshotProfileWriter::kArtificialRootId, Image::kHeaderSize);
}
#endif
// Heap page objects start here.
for (auto entry : objects_) {
ASSERT(entry.is_object());
const Object& obj = *entry.obj;
#if defined(DART_PRECOMPILER)
AutoTraceImage(obj, section_start, stream);
const char* object_name = namer_.SnapshotNameFor(entry);
#endif
auto const object_start = stream->Position();
NoSafepointScope no_safepoint;
// Write object header with the mark and read-only bits set.
stream->WriteTargetWord(GetMarkedTags(obj));
if (obj.IsCompressedStackMaps()) {
const CompressedStackMaps& map = CompressedStackMaps::Cast(obj);
const intptr_t payload_size = map.payload_size();
stream->WriteFixed<uint32_t>(
map.ptr()->untag()->payload()->flags_and_size());
stream->WriteBytes(map.ptr()->untag()->payload()->data(), payload_size);
} else if (obj.IsCodeSourceMap()) {
const CodeSourceMap& map = CodeSourceMap::Cast(obj);
stream->WriteTargetWord(map.Length());
ASSERT_EQUAL(stream->Position() - object_start,
compiler::target::CodeSourceMap::HeaderSize());
stream->WriteBytes(map.Data(), map.Length());
} else if (obj.IsPcDescriptors()) {
const PcDescriptors& desc = PcDescriptors::Cast(obj);
stream->WriteTargetWord(desc.Length());
ASSERT_EQUAL(stream->Position() - object_start,
compiler::target::PcDescriptors::HeaderSize());
stream->WriteBytes(desc.ptr()->untag()->data(), desc.Length());
} else if (obj.IsString()) {
const String& str = String::Cast(obj);
RELEASE_ASSERT(String::GetCachedHash(str.ptr()) != 0);
RELEASE_ASSERT(str.IsOneByteString() || str.IsTwoByteString());
#if !defined(HASH_IN_OBJECT_HEADER)
stream->WriteTargetWord(static_cast<uword>(str.ptr()->untag()->hash()));
#endif
stream->WriteTargetWord(static_cast<uword>(str.ptr()->untag()->length()));
ASSERT_EQUAL(stream->Position() - object_start,
compiler::target::String::InstanceSize());
stream->WriteBytes(
str.IsOneByteString()
? static_cast<const void*>(OneByteString::DataStart(str))
: static_cast<const void*>(TwoByteString::DataStart(str)),
str.Length() * (str.IsOneByteString()
? OneByteString::kBytesPerElement
: TwoByteString::kBytesPerElement));
} else {
const Class& clazz = Class::Handle(obj.clazz());
FATAL("Unsupported class %s in rodata section.\n", clazz.ToCString());
}
stream->Align(compiler::target::ObjectAlignment::kObjectAlignment);
ASSERT_EQUAL(stream->Position() - object_start, SizeInSnapshot(obj));
#if defined(DART_PRECOMPILER)
AddDataSymbol(object_name, object_start, stream->Position() - object_start);
#endif
}
}
static constexpr uword kReadOnlyGCBits =
UntaggedObject::OldBit::encode(true) |
UntaggedObject::OldAndNotMarkedBit::encode(false) |
UntaggedObject::OldAndNotRememberedBit::encode(true) |
UntaggedObject::NewBit::encode(false);
uword ImageWriter::GetMarkedTags(classid_t cid,
intptr_t size,
bool is_canonical /* = false */) {
// UntaggedObject::SizeTag expects a size divisible by kObjectAlignment and
// checks this in debug mode, but the size on the target machine may not be
// divisible by the host machine's object alignment if they differ.
//
// We define [adjusted_size] as [size] * m, where m is the host alignment
// divided by the target alignment. This means [adjusted_size] encodes on the
// host machine to the same bits that decode to [size] on the target machine.
// That is,
// [adjusted_size] / host align ==
// [size] * (host align / target align) / host align ==
// [size] / target align
//
// Since alignments are always powers of 2, we use shifts and logs.
const intptr_t adjusted_size =
size << (kObjectAlignmentLog2 -
compiler::target::ObjectAlignment::kObjectAlignmentLog2);
return kReadOnlyGCBits | UntaggedObject::ClassIdTag::encode(cid) |
UntaggedObject::SizeTag::encode(adjusted_size) |
UntaggedObject::CanonicalBit::encode(is_canonical);
}
uword ImageWriter::GetMarkedTags(const Object& obj) {
uword tags = GetMarkedTags(obj.ptr()->untag()->GetClassId(),
SizeInSnapshot(obj), obj.IsCanonical());
#if defined(HASH_IN_OBJECT_HEADER)
tags = UntaggedObject::HashTag::update(obj.ptr()->untag()->GetHeaderHash(),
tags);
#endif
return tags;
}
const char* ImageWriter::SectionSymbol(ProgramSection section, bool vm) {
switch (section) {
case ProgramSection::Text:
return vm ? kVmSnapshotInstructionsAsmSymbol
: kIsolateSnapshotInstructionsAsmSymbol;
case ProgramSection::Data:
return vm ? kVmSnapshotDataAsmSymbol : kIsolateSnapshotDataAsmSymbol;
case ProgramSection::Bss:
return vm ? kVmSnapshotBssAsmSymbol : kIsolateSnapshotBssAsmSymbol;
case ProgramSection::BuildId:
return kSnapshotBuildIdAsmSymbol;
}
UNREACHABLE();
return nullptr;
}
#if (defined(DART_TARGET_OS_MACOS) || defined(DART_TARGET_OS_MACOS_IOS)) && \
defined(TARGET_ARCH_ARM64)
// When generating ARM64 Mach-O LLVM tends to generate Compact Unwind Info
// (__unwind_info) rather than traditional DWARF unwinding information
// (__eh_frame).
//
// Unfortunately when generating __unwind_info LLVM seems to only apply CFI
// rules to the region between two non-local symbols that contains these CFI
// directives. In other words given:
//
// Abc:
// .cfi_startproc
// .cfi_def_cfa x29, 16
// .cfi_offset x30, -8
// .cfi_offset x29, -16
// ;; ...
// Xyz:
// ;; ...
// .cfi_endproc
//
// __unwind_info would specify proper unwinding information only for the region
// between Abc and Xyz symbols. And the region Xyz onwards will have no
// unwinding information.
//
// There also seems to be a difference in how unwinding information is
// canonicalized and compressed: when building __unwind_info from CFI directives
// LLVM will fold together similar entries, the same does not happen for
// __eh_frame. This means that emitting CFI directives for each function would
// balloon the size of __eh_frame.
//
// Hence to work around the problem of incorrect __unwind_info without
// ballooning snapshot size when __eh_frame is generated we choose to emit CFI
// directives per function specifically on ARM64 Mac OS X and iOS.
//
// See also |useCompactUnwind| method in LLVM (https://github.com/llvm/llvm-project/blob/b27430f9f46b88bcd54d992debc8d72e131e1bd0/llvm/lib/MC/MCObjectFileInfo.cpp#L28-L50)
#define EMIT_UNWIND_DIRECTIVES_PER_FUNCTION 1
#endif
void ImageWriter::WriteText(bool vm) {
const bool bare_instruction_payloads = FLAG_precompiled_mode;
// Start snapshot at page boundary.
intptr_t alignment_padding = 0;
if (!EnterSection(ProgramSection::Text, vm, ImageWriter::kTextAlignment,
&alignment_padding)) {
return;
}
intptr_t text_offset = 0;
#if defined(DART_PRECOMPILER)
// Parent used for later profile objects. Starts off as the Image. When
// writing bare instructions payloads, this is later updated with the
// InstructionsSection object which contains all the bare payloads.
V8SnapshotProfileWriter::ObjectId parent_id(offset_space_, text_offset);
#endif
// This head also provides the gap to make the instructions snapshot
// look like a Page.
const intptr_t image_size = Utils::RoundUp(
next_text_offset_, compiler::target::ObjectAlignment::kObjectAlignment);
text_offset += WriteTargetWord(image_size);
// Output the offset to the InstructionsSection object from the start of the
// image, if any.
text_offset +=
WriteTargetWord(FLAG_precompiled_mode ? Image::kHeaderSize
: Image::kNoInstructionsSection);
// Zero values for the rest of the Image object header bytes.
text_offset += Align(Image::kHeaderSize, 0, text_offset);
ASSERT_EQUAL(text_offset, Image::kHeaderSize);
#if defined(DART_PRECOMPILER)
const char* instructions_symbol = SectionSymbol(ProgramSection::Text, vm);
ASSERT(instructions_symbol != nullptr);
intptr_t instructions_label = SectionLabel(ProgramSection::Text, vm);
ASSERT(instructions_label > 0);
const char* bss_symbol = SectionSymbol(ProgramSection::Bss, vm);
ASSERT(bss_symbol != nullptr);
intptr_t bss_label = SectionLabel(ProgramSection::Bss, vm);
ASSERT(bss_label > 0);
if (profile_writer_ != nullptr) {
profile_writer_->SetObjectTypeAndName(parent_id, image_type_,
instructions_symbol);
profile_writer_->AttributeBytesTo(
parent_id, ImageWriter::kTextAlignment + alignment_padding);
profile_writer_->AddRoot(parent_id);
}
if (FLAG_precompiled_mode) {
const intptr_t section_header_length =
compiler::target::InstructionsSection::HeaderSize();
// Calculated using next_text_offset_, which doesn't include post-payload
// padding to object alignment. Note that if not in bare instructions mode,
// the section has no contents, instead the instructions objects follow it.
const intptr_t section_payload_length =
bare_instruction_payloads
? next_text_offset_ - text_offset - section_header_length
: 0;
const intptr_t section_size =
compiler::target::InstructionsSection::InstanceSize(
section_payload_length);
const V8SnapshotProfileWriter::ObjectId id(offset_space_, text_offset);
if (profile_writer_ != nullptr) {
profile_writer_->SetObjectTypeAndName(id, instructions_section_type_,
instructions_symbol);
profile_writer_->AttributeBytesTo(id,
section_size - section_payload_length);
const intptr_t element_offset = id.nonce() - parent_id.nonce();
profile_writer_->AttributeReferenceTo(
parent_id,
V8SnapshotProfileWriter::Reference::Element(element_offset), id);
// Later objects will have the InstructionsSection as a parent if in
// bare instructions mode, otherwise the image.
if (bare_instruction_payloads) {
parent_id = id;
}
}
// Add the RawInstructionsSection header.
text_offset +=
WriteTargetWord(GetMarkedTags(kInstructionsSectionCid, section_size));
// An InstructionsSection has five fields:
// 1) The length of the payload.
text_offset += WriteTargetWord(section_payload_length);
// 2) The BSS offset from this section.
text_offset += Relocation(text_offset, instructions_label, bss_label);
// 3) The relocated address of the instructions.
text_offset += RelocatedAddress(text_offset, instructions_label);
// 4) The GNU build ID note offset from this section.
text_offset += Relocation(text_offset, instructions_label,
SectionLabel(ProgramSection::BuildId, vm));
const intptr_t section_contents_alignment =
bare_instruction_payloads
? compiler::target::Instructions::kBarePayloadAlignment
: compiler::target::ObjectAlignment::kObjectAlignment;
const intptr_t alignment_offset =
compiler::target::ObjectAlignment::kOldObjectAlignmentOffset;
const intptr_t expected_size =
bare_instruction_payloads
? compiler::target::InstructionsSection::HeaderSize()
: compiler::target::InstructionsSection::InstanceSize(0);
text_offset +=
Align(section_contents_alignment, alignment_offset, text_offset);
ASSERT_EQUAL(text_offset - id.nonce(), expected_size);
}
#endif
#if !defined(EMIT_UNWIND_DIRECTIVES_PER_FUNCTION)
FrameUnwindPrologue();
#endif
#if defined(DART_PRECOMPILER)
PcDescriptors& descriptors = PcDescriptors::Handle(zone_);
#endif
ASSERT(offset_space_ != IdSpace::kSnapshot);
for (intptr_t i = 0; i < instructions_.length(); i++) {
auto& data = instructions_[i];
const bool is_trampoline = data.trampoline_bytes != nullptr;
ASSERT_EQUAL(data.text_offset_, text_offset);
#if defined(DART_PRECOMPILER)
const char* object_name = namer_.SnapshotNameFor(data);
if (profile_writer_ != nullptr) {
const V8SnapshotProfileWriter::ObjectId id(offset_space_, text_offset);
auto const type = is_trampoline ? trampoline_type_ : instructions_type_;
const intptr_t size = is_trampoline ? data.trampoline_length
: SizeInSnapshot(data.insns_->ptr());
profile_writer_->SetObjectTypeAndName(id, type, object_name);
profile_writer_->AttributeBytesTo(id, size);
const intptr_t element_offset = id.nonce() - parent_id.nonce();
profile_writer_->AttributeReferenceTo(
parent_id,
V8SnapshotProfileWriter::Reference::Element(element_offset), id);
}
#endif
if (is_trampoline) {
text_offset += WriteBytes(data.trampoline_bytes, data.trampoline_length);
delete[] data.trampoline_bytes;
data.trampoline_bytes = nullptr;
continue;
}
const intptr_t instr_start = text_offset;
const auto& insns = *data.insns_;
// 1. Write from the object start to the payload start. This includes the
// object header and the fixed fields. Not written for AOT snapshots using
// bare instructions.
if (!bare_instruction_payloads) {
NoSafepointScope no_safepoint;
// Write Instructions with the mark and read-only bits set.
text_offset += WriteTargetWord(GetMarkedTags(insns));
text_offset += WriteFixed(insns.untag()->size_and_flags_);
text_offset +=
Align(compiler::target::Instructions::kNonBarePayloadAlignment,
compiler::target::ObjectAlignment::kOldObjectAlignmentOffset,
text_offset);
}
ASSERT_EQUAL(text_offset - instr_start,
compiler::target::Instructions::HeaderSize());
#if defined(DART_PRECOMPILER)
const auto& code = *data.code_;
// 2. Add a symbol for the code at the entry point in precompiled snapshots.
// Linux's perf uses these labels.
AddCodeSymbol(code, object_name, text_offset);
#endif
#if defined(EMIT_UNWIND_DIRECTIVES_PER_FUNCTION)
FrameUnwindPrologue();
#endif
{
NoSafepointScope no_safepoint;
// 3. Write from the payload start to payload end. For AOT snapshots
// with bare instructions, this is the only part serialized other than
// any padding needed for alignment.
auto const payload_start =
reinterpret_cast<const uint8_t*>(insns.PayloadStart());
// Double-check the payload alignment, since we will load and write
// target-sized words starting from that address.
ASSERT(Utils::IsAligned(payload_start, compiler::target::kWordSize));
const uword payload_size = insns.Size();
auto const payload_end = payload_start + payload_size;
auto cursor = payload_start;
#if defined(DART_PRECOMPILER)
descriptors = code.pc_descriptors();
PcDescriptors::Iterator iterator(
descriptors, /*kind_mask=*/UntaggedPcDescriptors::kBSSRelocation);
while (iterator.MoveNext()) {
// We only generate BSS relocations in the precompiler.
ASSERT(FLAG_precompiled_mode);
auto const next_reloc_offset = iterator.PcOffset();
auto const next_reloc_address = payload_start + next_reloc_offset;
// We only generate BSS relocations that are target word-sized and at
// target word-aligned offsets in the payload. Double-check this.
ASSERT(
Utils::IsAligned(next_reloc_address, compiler::target::kWordSize));
text_offset += WriteBytes(cursor, next_reloc_address - cursor);
// The instruction stream at the relocation position holds the target
// offset into the BSS section.
const auto target_offset =
*reinterpret_cast<const compiler::target::word*>(
next_reloc_address);
text_offset += Relocation(text_offset, instructions_label, text_offset,
bss_label, target_offset);
cursor = next_reloc_address + compiler::target::kWordSize;
}
#endif
text_offset += WriteBytes(cursor, payload_end - cursor);
}
// 4. Add appropriate padding. Note we can't simply copy from the object
// because the host object may have less alignment filler than the target
// object in the cross-word case.
const intptr_t alignment =
bare_instruction_payloads
? compiler::target::Instructions::kBarePayloadAlignment
: compiler::target::ObjectAlignment::kObjectAlignment;
text_offset += AlignWithBreakInstructions(alignment, text_offset);
ASSERT_EQUAL(text_offset - instr_start, SizeInSnapshot(insns.ptr()));
#if defined(EMIT_UNWIND_DIRECTIVES_PER_FUNCTION)
FrameUnwindEpilogue();
#endif
}
// Should be a no-op unless writing bare instruction payloads, in which case
// we need to add post-payload padding for the InstructionsSection object.
// Since this follows instructions, we'll use break instructions for padding.
ASSERT(bare_instruction_payloads ||
Utils::IsAligned(text_offset,
compiler::target::ObjectAlignment::kObjectAlignment));
text_offset += AlignWithBreakInstructions(
compiler::target::ObjectAlignment::kObjectAlignment, text_offset);
ASSERT_EQUAL(text_offset, image_size);
#if !defined(EMIT_UNWIND_DIRECTIVES_PER_FUNCTION)
FrameUnwindEpilogue();
#endif
ExitSection(ProgramSection::Text, vm, text_offset);
}
intptr_t ImageWriter::AlignWithBreakInstructions(intptr_t alignment,
intptr_t offset) {
intptr_t bytes_written = 0;
uword remaining;
for (remaining = Utils::RoundUp(offset, alignment) - offset;
remaining >= compiler::target::kWordSize;
remaining -= compiler::target::kWordSize) {
bytes_written += WriteTargetWord(kBreakInstructionFiller);
}
#if defined(TARGET_ARCH_ARM)
// All instructions are 4 bytes long on ARM architectures, so on 32-bit ARM
// there won't be any padding.
ASSERT_EQUAL(remaining, 0);
#elif defined(TARGET_ARCH_ARM64)
// All instructions are 4 bytes long on ARM architectures, so on 64-bit ARM
// there is only 0 or 4 bytes of padding.
if (remaining != 0) {
ASSERT_EQUAL(remaining, 4);
bytes_written += WriteBytes(&kBreakInstructionFiller, remaining);
}
#elif defined(TARGET_ARCH_X64) || defined(TARGET_ARCH_IA32) || \
defined(TARGET_ARCH_RISCV32) || defined(TARGET_ARCH_RISCV64)
// The break instruction is a single byte, repeated to fill a word.
bytes_written += WriteBytes(&kBreakInstructionFiller, remaining);
#else
#error Unexpected architecture.
#endif
ASSERT_EQUAL(bytes_written, Utils::RoundUp(offset, alignment) - offset);
return bytes_written;
}
#if defined(DART_PRECOMPILER)
// Indices are log2(size in bytes).
static constexpr const char* kSizeDirectives[] = {".byte", ".2byte", ".long",
".quad"};
static constexpr const char* kWordDirective =
kSizeDirectives[compiler::target::kWordSizeLog2];
class DwarfAssemblyStream : public DwarfWriteStream {
public:
explicit DwarfAssemblyStream(Zone* zone,
BaseWriteStream* stream,
const IntMap<const char*>& label_to_name)
: zone_(ASSERT_NOTNULL(zone)),
stream_(ASSERT_NOTNULL(stream)),
label_to_name_(label_to_name) {}
void sleb128(intptr_t value) { stream_->Printf(".sleb128 %" Pd "\n", value); }
void uleb128(uintptr_t value) {
stream_->Printf(".uleb128 %" Pd "\n", value);
}
void u1(uint8_t value) {
stream_->Printf("%s %u\n", kSizeDirectives[kInt8SizeLog2], value);
}
void u2(uint16_t value) {
stream_->Printf("%s %u\n", kSizeDirectives[kInt16SizeLog2], value);
}
void u4(uint32_t value) {
stream_->Printf("%s %" Pu32 "\n", kSizeDirectives[kInt32SizeLog2], value);
}
void u8(uint64_t value) {
stream_->Printf("%s %" Pu64 "\n", kSizeDirectives[kInt64SizeLog2], value);
}
void string(const char* cstr) { // NOLINT
stream_->Printf(".string \"%s\"\n", cstr); // NOLINT
}
void WritePrefixedLength(const char* prefix, std::function<void()> body) {
ASSERT(prefix != nullptr);
const char* const length_prefix_symbol =
OS::SCreate(zone_, ".L%s_length_prefix", prefix);
// Assignment to temp works around buggy Mac assembler.
stream_->Printf("L%s_size = .L%s_end - .L%s_start\n", prefix, prefix,
prefix);
// We assume DWARF v2 currently, so all sizes are 32-bit.
stream_->Printf("%s: %s L%s_size\n", length_prefix_symbol,
kSizeDirectives[kInt32SizeLog2], prefix);
// All sizes for DWARF sections measure the size of the section data _after_
// the size value.
stream_->Printf(".L%s_start:\n", prefix);
body();
stream_->Printf(".L%s_end:\n", prefix);
}
void OffsetFromSymbol(intptr_t label, intptr_t offset) {
const char* symbol = label_to_name_.Lookup(label);
ASSERT(symbol != nullptr);
if (offset == 0) {
PrintNamedAddress(symbol);
} else {
PrintNamedAddressWithOffset(symbol, offset);
}
}
// No-op, we'll be using labels.
void InitializeAbstractOrigins(intptr_t size) {}
void RegisterAbstractOrigin(intptr_t index) {
// Label for DW_AT_abstract_origin references
stream_->Printf(".Lfunc%" Pd ":\n", index);
}
void AbstractOrigin(intptr_t index) {
// Assignment to temp works around buggy Mac assembler.
stream_->Printf("Ltemp%" Pd " = .Lfunc%" Pd " - %s\n", temp_, index,
kDebugInfoLabel);
stream_->Printf("%s Ltemp%" Pd "\n", kSizeDirectives[kInt32SizeLog2],
temp_);
temp_++;
}
// Methods for writing the assembly prologues for various DWARF sections.
void AbbreviationsPrologue() {
#if defined(DART_TARGET_OS_MACOS) || defined(DART_TARGET_OS_MACOS_IOS)
stream_->WriteString(".section __DWARF,__debug_abbrev,regular,debug\n");
#elif defined(DART_TARGET_OS_LINUX) || defined(DART_TARGET_OS_ANDROID) || \
defined(DART_TARGET_OS_FUCHSIA)
stream_->WriteString(".section .debug_abbrev,\"\"\n");
#else
UNIMPLEMENTED();
#endif
}
void DebugInfoPrologue() {
#if defined(DART_TARGET_OS_MACOS) || defined(DART_TARGET_OS_MACOS_IOS)
stream_->WriteString(".section __DWARF,__debug_info,regular,debug\n");
#elif defined(DART_TARGET_OS_LINUX) || defined(DART_TARGET_OS_ANDROID) || \
defined(DART_TARGET_OS_FUCHSIA)
stream_->WriteString(".section .debug_info,\"\"\n");
#else
UNIMPLEMENTED();
#endif
// Used to calculate abstract origin values.
stream_->Printf("%s:\n", kDebugInfoLabel);
}
void LineNumberProgramPrologue() {
#if defined(DART_TARGET_OS_MACOS) || defined(DART_TARGET_OS_MACOS_IOS)
stream_->WriteString(".section __DWARF,__debug_line,regular,debug\n");
#elif defined(DART_TARGET_OS_LINUX) || defined(DART_TARGET_OS_ANDROID) || \
defined(DART_TARGET_OS_FUCHSIA)
stream_->WriteString(".section .debug_line,\"\"\n");
#else
UNIMPLEMENTED();
#endif
}
private:
static constexpr const char* kDebugInfoLabel = ".Ldebug_info";
void PrintNamedAddress(const char* name) {
stream_->Printf("%s \"%s\"\n", kWordDirective, name);
}
void PrintNamedAddressWithOffset(const char* name, intptr_t offset) {
stream_->Printf("%s \"%s\" + %" Pd "\n", kWordDirective, name, offset);
}
Zone* const zone_;
BaseWriteStream* const stream_;
const IntMap<const char*>& label_to_name_;
intptr_t temp_ = 0;
DISALLOW_COPY_AND_ASSIGN(DwarfAssemblyStream);
};
static inline Dwarf* AddDwarfIfUnstripped(
Zone* zone,
bool strip,
Elf* elf,
const Trie<const char>* deobfuscation_trie) {
if (!strip) {
if (elf != nullptr) {
// Reuse the existing DWARF object.
ASSERT(elf->dwarf() != nullptr);
return elf->dwarf();
}
return new (zone) Dwarf(zone, deobfuscation_trie);
}
return nullptr;
}
AssemblyImageWriter::AssemblyImageWriter(
Thread* thread,
BaseWriteStream* stream,
const Trie<const char>* deobfuscation_trie,
bool strip,
Elf* debug_elf)
: ImageWriter(thread, /*generates_assembly=*/true, deobfuscation_trie),
assembly_stream_(stream),
assembly_dwarf_(
AddDwarfIfUnstripped(zone_, strip, debug_elf, deobfuscation_trie)),
debug_elf_(debug_elf),
label_to_symbol_name_(zone_) {
// Set up the label mappings for the section symbols for use in relocations.
for (intptr_t i = 0; i < kNumProgramSections; i++) {
auto const section = static_cast<ProgramSection>(i);
auto const vm_name = SectionSymbol(section, /*vm=*/true);
auto const vm_label = SectionLabel(section, /*vm=*/true);
label_to_symbol_name_.Insert(vm_label, vm_name);
auto const isolate_name = SectionSymbol(section, /*vm=*/false);
auto const isolate_label = SectionLabel(section, /*vm=*/false);
if (vm_label != isolate_label) {
label_to_symbol_name_.Insert(isolate_label, isolate_name);
} else {
// Make sure the names also match.
ASSERT_EQUAL(strcmp(vm_name, isolate_name), 0);
}
}
}
void AssemblyImageWriter::Finalize() {
if (assembly_dwarf_ != nullptr) {
DwarfAssemblyStream dwarf_stream(zone_, assembly_stream_,
label_to_symbol_name_);
dwarf_stream.AbbreviationsPrologue();
assembly_dwarf_->WriteAbbreviations(&dwarf_stream);
dwarf_stream.DebugInfoPrologue();
assembly_dwarf_->WriteDebugInfo(&dwarf_stream);
dwarf_stream.LineNumberProgramPrologue();
assembly_dwarf_->WriteLineNumberProgram(&dwarf_stream);
}
if (debug_elf_ != nullptr) {
debug_elf_->Finalize();
}
#if defined(DART_TARGET_OS_LINUX) || defined(DART_TARGET_OS_ANDROID) || \
defined(DART_TARGET_OS_FUCHSIA)
// Non-executable stack.
assembly_stream_->WriteString(".section .note.GNU-stack,\"\"\n");
#endif
}
void ImageWriter::SnapshotTextObjectNamer::AddNonUniqueNameFor(
BaseTextBuffer* buffer,
const Object& object) {
if (object.IsCode()) {
const Code& code = Code::Cast(object);
if (code.IsStubCode()) {
buffer->AddString("stub ");
insns_ = code.instructions();
const char* name = StubCode::NameOfStub(insns_.EntryPoint());
ASSERT(name != nullptr);
buffer->AddString(name);
} else {
if (code.IsAllocationStubCode()) {
buffer->AddString("new ");
} else if (code.IsTypeTestStubCode()) {
buffer->AddString("assert type is ");
} else {
ASSERT(code.IsFunctionCode());
}
owner_ = code.owner();
AddNonUniqueNameFor(buffer, owner_);
}
} else if (object.IsClass()) {
const char* name = Class::Cast(object).UserVisibleNameCString();
const char* deobfuscated_name =
ImageWriter::Deobfuscate(zone_, deobfuscation_trie_, name);
buffer->AddString(deobfuscated_name);
} else if (object.IsAbstractType()) {
const AbstractType& type = AbstractType::Cast(object);
if (deobfuscation_trie_ == nullptr) {
// Print directly to the output buffer.
type.PrintName(Object::kUserVisibleName, buffer);
} else {
// Use an intermediate buffer for deobfuscation purposes.
ZoneTextBuffer temp_buffer(zone_);
type.PrintName(Object::kUserVisibleName, &temp_buffer);
const char* deobfuscated_name = ImageWriter::Deobfuscate(
zone_, deobfuscation_trie_, temp_buffer.buffer());
buffer->AddString(deobfuscated_name);
}
} else if (object.IsFunction()) {
const Function& func = Function::Cast(object);
NameFormattingParams params(
{Object::kUserVisibleName, Object::NameDisambiguation::kNo});
if (deobfuscation_trie_ == nullptr) {
// Print directly to the output buffer.
func.PrintName(params, buffer);
} else {
// Use an intermediate buffer for deobfuscation purposes.
ZoneTextBuffer temp_buffer(zone_);
func.PrintName(params, &temp_buffer);
const char* deobfuscated_name = ImageWriter::Deobfuscate(
zone_, deobfuscation_trie_, temp_buffer.buffer());
buffer->AddString(deobfuscated_name);
}
} else if (object.IsCompressedStackMaps()) {
buffer->AddString("CompressedStackMaps");
} else if (object.IsPcDescriptors()) {
buffer->AddString("PcDescriptors");
} else if (object.IsCodeSourceMap()) {
buffer->AddString("CodeSourceMap");
} else if (object.IsString()) {
const String& str = String::Cast(object);
if (str.IsOneByteString()) {
buffer->AddString("OneByteString");
} else if (str.IsTwoByteString()) {
buffer->AddString("TwoByteString");
}
} else {
UNREACHABLE();
}
}
void ImageWriter::SnapshotTextObjectNamer::ModifyForAssembly(
BaseTextBuffer* buffer) {
if (buffer->buffer()[0] == 'L') {
// Assembler treats labels starting with `L` as local which can cause
// some issues down the line e.g. on Mac the linker might fail to encode
// compact unwind information because multiple functions end up being
// treated as a single function. See https://github.com/flutter/flutter/issues/102281.
//
// Avoid this by prepending an underscore.
auto* const result = OS::SCreate(zone_, "_%s", buffer->buffer());
buffer->Clear();
buffer->AddString(result);
}
auto* const pair = usage_count_.Lookup(buffer->buffer());
if (pair == nullptr) {
usage_count_.Insert({buffer->buffer(), 1});
} else {
buffer->Printf(" (#%" Pd ")", ++pair->value);
}
}
const char* ImageWriter::SnapshotTextObjectNamer::SnapshotNameFor(
const InstructionsData& data) {
ZoneTextBuffer printer(zone_);
if (data.trampoline_bytes != nullptr) {
printer.AddString("Trampoline");
} else {
AddNonUniqueNameFor(&printer, *data.code_);
}
if (for_assembly_) {
ModifyForAssembly(&printer);
}
return printer.buffer();
}
const char* ImageWriter::SnapshotTextObjectNamer::SnapshotNameFor(
const ObjectData& data) {
ASSERT(data.is_object());
ZoneTextBuffer printer(zone_);
if (data.is_original_object()) {
const Object& obj = *data.obj;
AddNonUniqueNameFor(&printer, obj);
#if defined(SNAPSHOT_BACKTRACE)
// It's less useful knowing the parent of a String than other read-only
// data objects, and this avoids us having to handle other classes
// in AddNonUniqueNameFor.
if (!obj.IsString()) {
const Object& parent = *data.parent;
if (!parent.IsNull()) {
printer.AddString(" (");
AddNonUniqueNameFor(&printer, parent);
printer.AddString(")");
}
}
#endif
} else {
printer.AddString("RawBytes");
}
if (for_assembly_) {
ModifyForAssembly(&printer);
}
return printer.buffer();
}
Trie<const char>* ImageWriter::CreateReverseObfuscationTrie(Thread* thread) {
auto* const zone = thread->zone();
auto* const map_array = thread->isolate_group()->obfuscation_map();
if (map_array == nullptr) return nullptr;
Trie<const char>* trie = nullptr;
for (intptr_t i = 0; map_array[i] != nullptr; i += 2) {
auto const key = map_array[i];
auto const value = map_array[i + 1];
ASSERT(value != nullptr);
// Don't include identity mappings.
if (strcmp(key, value) == 0) continue;
// Otherwise, any value in the obfuscation map should be a valid key.
ASSERT(Trie<const char>::IsValidKey(value));
trie = Trie<const char>::AddString(zone, trie, value, key);
}
return trie;
}
const char* ImageWriter::Deobfuscate(Zone* zone,
const Trie<const char>* trie,
const char* cstr) {
if (trie == nullptr) return cstr;
TextBuffer buffer(256);
// Used to avoid Zone-allocating strings if no deobfuscation was performed.
bool changed = false;
intptr_t i = 0;
while (cstr[i] != '\0') {
intptr_t offset;
auto const value = trie->Lookup(cstr + i, &offset);
if (offset == 0) {
// The first character was an invalid key element (that isn't the null
// terminator due to the while condition), copy it and skip to the next.
buffer.AddChar(cstr[i++]);
} else if (value != nullptr) {
changed = true;
buffer.AddString(value);
} else {
buffer.AddRaw(reinterpret_cast<const uint8_t*>(cstr + i), offset);
}
i += offset;
}
if (!changed) return cstr;
return OS::SCreate(zone, "%s", buffer.buffer());
}
void AssemblyImageWriter::WriteBss(bool vm) {
EnterSection(ProgramSection::Bss, vm, ImageWriter::kBssAlignment);
auto const entry_count =
vm ? BSS::kVmEntryCount : BSS::kIsolateGroupEntryCount;
for (intptr_t i = 0; i < entry_count; i++) {
// All bytes in the .bss section must be zero.
WriteTargetWord(0);
}
ExitSection(ProgramSection::Bss, vm,
entry_count * compiler::target::kWordSize);
}
void AssemblyImageWriter::WriteROData(NonStreamingWriteStream* clustered_stream,
bool vm) {
if (!EnterSection(ProgramSection::Data, vm, ImageWriter::kRODataAlignment)) {
return;
}
// The clustered stream already has some data on it from the serializer, so
// make sure that the read-only objects start at the appropriate alignment
// within the stream, as we'll write the entire clustered stream to the
// assembly output (which was aligned in EnterSection).
const intptr_t start_position = clustered_stream->Position();
clustered_stream->Align(ImageWriter::kRODataAlignment);
if (profile_writer_ != nullptr) {
// Attribute any padding needed to the artificial root.
const intptr_t padding = clustered_stream->Position() - start_position;
profile_writer_->AttributeBytesTo(
V8SnapshotProfileWriter::kArtificialRootId, padding);
}
// First write the read-only data objects to the clustered stream.
ImageWriter::WriteROData(clustered_stream, vm);
// Next, write the bytes of the clustered stream (along with any symbols
// if appropriate) to the assembly output.
const uint8_t* bytes = clustered_stream->buffer();
const intptr_t len = clustered_stream->bytes_written();
intptr_t last_position = 0;
for (const auto& symbol : *current_symbols_) {
WriteBytes(bytes + last_position, symbol.offset - last_position);
assembly_stream_->Printf("\"%s\":\n", symbol.name);
#if defined(DART_TARGET_OS_LINUX) || defined(DART_TARGET_OS_ANDROID) || \
defined(DART_TARGET_OS_FUCHSIA)
// Output size and type of the read-only data symbol to the assembly stream.
assembly_stream_->Printf(".size \"%s\", %zu\n", symbol.name, symbol.size);
assembly_stream_->Printf(".type \"%s\", %%object\n", symbol.name);
#elif defined(DART_TARGET_OS_MACOS) || defined(DART_TARGET_OS_MACOS_IOS)
// MachO symbol tables don't include the size of the symbol, so don't bother
// printing it to the assembly output.
#else
UNIMPLEMENTED();
#endif
last_position = symbol.offset;
}
WriteBytes(bytes + last_position, len - last_position);
ExitSection(ProgramSection::Data, vm, len);
}
bool AssemblyImageWriter::EnterSection(ProgramSection section,
bool vm,
intptr_t alignment,
intptr_t* alignment_padding) {
ASSERT(FLAG_precompiled_mode);
ASSERT(current_symbols_ == nullptr);
bool global_symbol = false;
switch (section) {
case ProgramSection::Text:
if (debug_elf_ != nullptr) {
current_symbols_ =
new (zone_) ZoneGrowableArray<Elf::SymbolData>(zone_, 0);
}
assembly_stream_->WriteString(".text\n");
global_symbol = true;
break;
case ProgramSection::Data:
// We create a SymbolData array even if there is no debug_elf_ because we
// may be writing RO data symbols, and RO data is written in two steps:
// 1. Serializing the read-only data objects to the clustered stream
// 2. Writing the bytes of the clustered stream to the assembly output.
// Thus, we'll need to interleave the symbols with the cluster bytes
// during step 2.
current_symbols_ =
new (zone_) ZoneGrowableArray<Elf::SymbolData>(zone_, 0);
#if defined(DART_TARGET_OS_LINUX) || defined(DART_TARGET_OS_ANDROID) || \
defined(DART_TARGET_OS_FUCHSIA)
assembly_stream_->WriteString(".section .rodata\n");
#elif defined(DART_TARGET_OS_MACOS) || defined(DART_TARGET_OS_MACOS_IOS)
assembly_stream_->WriteString(".const\n");
#else
UNIMPLEMENTED();
#endif
global_symbol = true;
break;
case ProgramSection::Bss:
assembly_stream_->WriteString(".bss\n");
break;
case ProgramSection::BuildId:
break;
}
current_section_label_ = SectionLabel(section, vm);
ASSERT(current_section_label_ > 0);
if (global_symbol) {
assembly_stream_->Printf(".globl %s\n", SectionSymbol(section, vm));
}
intptr_t padding = Align(alignment, 0, 0);
if (alignment_padding != nullptr) {
*alignment_padding = padding;
}
assembly_stream_->Printf("%s:\n", SectionSymbol(section, vm));
return true;
}
static void ElfAddSection(
Elf* elf,
ImageWriter::ProgramSection section,
const char* symbol,
intptr_t label,
uint8_t* bytes,
intptr_t size,
ZoneGrowableArray<Elf::SymbolData>* symbols,
ZoneGrowableArray<Elf::Relocation>* relocations = nullptr) {
if (elf == nullptr) return;
switch (section) {
case ImageWriter::ProgramSection::Text:
elf->AddText(symbol, label, bytes, size, relocations, symbols);
break;
case ImageWriter::ProgramSection::Data:
elf->AddROData(symbol, label, bytes, size, relocations, symbols);
break;
default:
// Other sections are handled by the Elf object internally.
break;
}
}
void AssemblyImageWriter::ExitSection(ProgramSection name,
bool vm,
intptr_t size) {
// We should still be in the same section as the last EnterSection.
ASSERT_EQUAL(current_section_label_, SectionLabel(name, vm));
#if defined(DART_TARGET_OS_LINUX) || defined(DART_TARGET_OS_ANDROID) || \
defined(DART_TARGET_OS_FUCHSIA)
// Output the size of the section symbol to the assembly stream.
assembly_stream_->Printf(".size %s, %zu\n", SectionSymbol(name, vm), size);
assembly_stream_->Printf(".type %s, %%object\n", SectionSymbol(name, vm));
#elif defined(DART_TARGET_OS_MACOS) || defined(DART_TARGET_OS_MACOS_IOS)
// MachO symbol tables don't include the size of the symbol, so don't bother
// printing it to the assembly output.
#else
UNIMPLEMENTED();
#endif
// We need to generate a text segment of the appropriate size in the ELF
// for two reasons:
//
// * We need unique virtual addresses for each text section in the DWARF
// file and that the virtual addresses for payloads within those sections
// do not overlap.
//
// * Our tools for converting DWARF stack traces back to "normal" Dart
// stack traces calculate an offset into the appropriate instructions
// section, and then add that offset to the virtual address of the
// corresponding segment to get the virtual address for the frame.
//
// Since we don't want to add the actual contents of the segment in the
// separate debugging information, we pass nullptr for the bytes, which
// creates an appropriate NOBITS section instead of PROGBITS.
ElfAddSection(debug_elf_, name, SectionSymbol(name, vm),
current_section_label_, /*bytes=*/nullptr, size,
current_symbols_);
current_section_label_ = 0;
current_symbols_ = nullptr;
}
intptr_t AssemblyImageWriter::WriteTargetWord(word value) {
ASSERT(Utils::BitLength(value) <= compiler::target::kBitsPerWord);
// Padding is helpful for comparing the .S with --disassemble.
assembly_stream_->Printf("%s 0x%.*" Px "\n", kWordDirective,
2 * compiler::target::kWordSize, value);
return compiler::target::kWordSize;
}
intptr_t AssemblyImageWriter::Relocation(intptr_t section_offset,
intptr_t source_label,
intptr_t source_offset,
intptr_t target_label,
intptr_t target_offset) {
// TODO(dartbug.com/43274): Remove once we generate consistent build IDs
// between assembly snapshots and their debugging information.
if (target_label == SectionLabel(ProgramSection::BuildId, /*vm=*/false)) {
return WriteTargetWord(Image::kNoBuildId);
}
// All relocations are word-sized.
assembly_stream_->Printf("%s ", kWordDirective);
if (target_label == current_section_label_) {
assembly_stream_->WriteString("(.)");
target_offset -= section_offset;
} else {
const char* target_symbol = label_to_symbol_name_.Lookup(target_label);
ASSERT(target_symbol != nullptr);
assembly_stream_->Printf("%s", target_symbol);
}
if (target_offset != 0) {
assembly_stream_->Printf(" + %" Pd "", target_offset);
}
if (source_label == current_section_label_) {
assembly_stream_->WriteString(" - (.)");
source_offset -= section_offset;
} else {
const char* source_symbol = label_to_symbol_name_.Lookup(source_label);
ASSERT(source_symbol != nullptr);
assembly_stream_->Printf(" - %s", source_symbol);
}
if (source_offset != 0) {
assembly_stream_->Printf(" - %" Pd "", source_offset);
}
assembly_stream_->WriteString("\n");
return compiler::target::kWordSize;
}
void AssemblyImageWriter::AddCodeSymbol(const Code& code,
const char* symbol,
intptr_t offset) {
auto const label = next_label_++;
label_to_symbol_name_.Insert(label, symbol);
if (assembly_dwarf_ != nullptr) {
assembly_dwarf_->AddCode(code, label);
}
if (debug_elf_ != nullptr) {
current_symbols_->Add({symbol, elf::STT_FUNC, offset, code.Size(), label});
debug_elf_->dwarf()->AddCode(code, label);
}
assembly_stream_->Printf("\"%s\":\n", symbol);
#if defined(DART_TARGET_OS_LINUX) || defined(DART_TARGET_OS_ANDROID) || \
defined(DART_TARGET_OS_FUCHSIA)
// Output the size of the code symbol to the assembly stream.
assembly_stream_->Printf(".size \"%s\", %zu\n", symbol, code.Size());
assembly_stream_->Printf(".type \"%s\", %%function\n", symbol);
#elif defined(DART_TARGET_OS_MACOS) || defined(DART_TARGET_OS_MACOS_IOS)
// MachO symbol tables don't include the size of the symbol, so don't bother
// printing it to the assembly output.
#else
UNIMPLEMENTED();
#endif
}
void AssemblyImageWriter::AddDataSymbol(const char* symbol,
intptr_t offset,
size_t size) {
if (!FLAG_add_readonly_data_symbols) return;
auto const label = next_label_++;
label_to_symbol_name_.Insert(label, symbol);
current_symbols_->Add({symbol, elf::STT_OBJECT, offset, size, label});
}
void AssemblyImageWriter::FrameUnwindPrologue() {
// Creates DWARF's .debug_frame
// CFI = Call frame information
// CFA = Canonical frame address
assembly_stream_->WriteString(".cfi_startproc\n");
// Below .cfi_def_cfa defines CFA as caller's SP, while .cfi_offset R, offs
// tells unwinder that caller's value of register R is stored at address
// CFA+offs.
// In the code below we emit .cfi_offset directive in the specific order:
// PC first then FP. This should not actually matter, but we discovered
// that LLVM code responsible for emitting compact unwind information
// expects this specific ordering of CFI directives. If we don't
// follow the order then LLVM fails to emit compact unwind info and emits
// __eh_frame instead which is very large.
// See also https://github.com/llvm/llvm-project/issues/62574 and
// https://github.com/flutter/flutter/issues/126004.
#if defined(TARGET_ARCH_IA32)
UNREACHABLE();
#elif defined(TARGET_ARCH_X64)
assembly_stream_->WriteString(".cfi_def_cfa rbp, 16\n");
assembly_stream_->WriteString(".cfi_offset rip, -8\n");
assembly_stream_->WriteString(".cfi_offset rbp, -16\n");
#elif defined(TARGET_ARCH_ARM64)
COMPILE_ASSERT(R29 == FP);
COMPILE_ASSERT(R30 == LINK_REGISTER);
assembly_stream_->WriteString(".cfi_def_cfa x29, 16\n");
assembly_stream_->WriteString(".cfi_offset x30, -8\n");
assembly_stream_->WriteString(".cfi_offset x29, -16\n");
#elif defined(TARGET_ARCH_ARM)
#if defined(DART_TARGET_OS_MACOS) || defined(DART_TARGET_OS_MACOS_IOS)
COMPILE_ASSERT(FP == R7);
assembly_stream_->WriteString(".cfi_def_cfa r7, 8\n");
#else
COMPILE_ASSERT(FP == R11);
assembly_stream_->WriteString(".cfi_def_cfa r11, 8\n");
#endif
assembly_stream_->WriteString(".cfi_offset lr, -4\n");
#if defined(DART_TARGET_OS_MACOS) || defined(DART_TARGET_OS_MACOS_IOS)
COMPILE_ASSERT(FP == R7);
assembly_stream_->WriteString(".cfi_offset r7, -8\n");
#else
COMPILE_ASSERT(FP == R11);
assembly_stream_->WriteString(".cfi_offset r11, -8\n");
#endif
// libunwind on ARM may use .ARM.exidx instead of .debug_frame
#if !defined(DART_TARGET_OS_MACOS) && !defined(DART_TARGET_OS_MACOS_IOS)
COMPILE_ASSERT(FP == R11);
assembly_stream_->WriteString(".fnstart\n");
assembly_stream_->WriteString(".save {r11, lr}\n");
assembly_stream_->WriteString(".setfp r11, sp, #0\n");
#endif
#elif defined(TARGET_ARCH_RISCV32)
assembly_stream_->WriteString(".cfi_def_cfa fp, 0\n");
assembly_stream_->WriteString(".cfi_offset ra, -4\n");
assembly_stream_->WriteString(".cfi_offset fp, -8\n");
#elif defined(TARGET_ARCH_RISCV64)
assembly_stream_->WriteString(".cfi_def_cfa fp, 0\n");
assembly_stream_->WriteString(".cfi_offset ra, -8\n");
assembly_stream_->WriteString(".cfi_offset fp, -16\n");
#else
#error Unexpected architecture.
#endif
}
void AssemblyImageWriter::FrameUnwindEpilogue() {
#if defined(TARGET_ARCH_ARM)
#if !defined(DART_TARGET_OS_MACOS) && !defined(DART_TARGET_OS_MACOS_IOS)
assembly_stream_->WriteString(".fnend\n");
#endif
#endif
assembly_stream_->WriteString(".cfi_endproc\n");
}
intptr_t AssemblyImageWriter::WriteBytes(const void* bytes, intptr_t size) {
ASSERT(size >= 0);
auto const start = reinterpret_cast<const uint8_t*>(bytes);
auto const end_of_words =
start + Utils::RoundDown(size, compiler::target::kWordSize);
for (auto cursor = reinterpret_cast<const compiler::target::word*>(start);
cursor < reinterpret_cast<const compiler::target::word*>(end_of_words);
cursor++) {
WriteTargetWord(*cursor);
}
auto const end = start + size;
if (end != end_of_words) {
assembly_stream_->WriteString(kSizeDirectives[kInt8SizeLog2]);
for (auto cursor = end_of_words; cursor < end; cursor++) {
assembly_stream_->Printf("%s 0x%.2x", cursor != end_of_words ? "," : "",
*cursor);
}
assembly_stream_->WriteString("\n");
}
return size;
}
intptr_t AssemblyImageWriter::Align(intptr_t alignment,
intptr_t offset,
intptr_t position) {
ASSERT(offset == 0);
const intptr_t next_position = Utils::RoundUp(position, alignment);
assembly_stream_->Printf(".balign %" Pd ", 0\n", alignment);
return next_position - position;
}
#endif // defined(DART_PRECOMPILER)
#if defined(DART_PRECOMPILER)
BlobImageWriter::BlobImageWriter(Thread* thread,
NonStreamingWriteStream* vm_instructions,
NonStreamingWriteStream* isolate_instructions,
const Trie<const char>* deobfuscation_trie,
Elf* debug_elf,
Elf* elf)
: ImageWriter(thread, /*generates_assembly=*/false, deobfuscation_trie),
#else
BlobImageWriter::BlobImageWriter(Thread* thread,
NonStreamingWriteStream* vm_instructions,
NonStreamingWriteStream* isolate_instructions,
Elf* debug_elf,
Elf* elf)
: ImageWriter(thread, /*generates_assembly=*/false),
#endif
vm_instructions_(vm_instructions),
isolate_instructions_(isolate_instructions),
elf_(elf),
debug_elf_(debug_elf) {
#if defined(DART_PRECOMPILER)
ASSERT_EQUAL(FLAG_precompiled_mode, elf_ != nullptr);
ASSERT(debug_elf_ == nullptr || debug_elf_->dwarf() != nullptr);
#else
RELEASE_ASSERT(elf_ == nullptr);
#endif
}
intptr_t BlobImageWriter::WriteBytes(const void* bytes, intptr_t size) {
current_section_stream_->WriteBytes(bytes, size);
return size;
}
void BlobImageWriter::WriteBss(bool vm) {
#if defined(DART_PRECOMPILER)
// We don't actually write a BSS segment, it's created as part of the
// Elf constructor.
#endif
}
void BlobImageWriter::WriteROData(NonStreamingWriteStream* clustered_stream,
bool vm) {
#if defined(DART_PRECOMPILER)
const intptr_t start_position = clustered_stream->Position();
#endif
current_section_stream_ = ASSERT_NOTNULL(clustered_stream);
if (!EnterSection(ProgramSection::Data, vm, ImageWriter::kRODataAlignment)) {
return;
}
#if defined(DART_PRECOMPILER)
if (profile_writer_ != nullptr) {
// Attribute any padding needed to the artificial root.
const intptr_t padding = clustered_stream->Position() - start_position;
profile_writer_->AttributeBytesTo(
V8SnapshotProfileWriter::kArtificialRootId, padding);
}
#endif
ImageWriter::WriteROData(clustered_stream, vm);
ExitSection(ProgramSection::Data, vm, clustered_stream->bytes_written());
}
bool BlobImageWriter::EnterSection(ProgramSection section,
bool vm,
intptr_t alignment,
intptr_t* alignment_padding) {
#if defined(DART_PRECOMPILER)
ASSERT_EQUAL(elf_ != nullptr, FLAG_precompiled_mode);
ASSERT(current_relocations_ == nullptr);
ASSERT(current_symbols_ == nullptr);
#endif
ASSERT(section == ProgramSection::Data || current_section_stream_ == nullptr);
switch (section) {
case ProgramSection::Text:
current_section_stream_ =
ASSERT_NOTNULL(vm ? vm_instructions_ : isolate_instructions_);
#if defined(DART_PRECOMPILER)
current_relocations_ =
new (zone_) ZoneGrowableArray<Elf::Relocation>(zone_, 0);
current_symbols_ =
new (zone_) ZoneGrowableArray<Elf::SymbolData>(zone_, 0);
#endif
break;
case ProgramSection::Data:
// The stream to use is passed into WriteROData and set there.
ASSERT(current_section_stream_ != nullptr);
#if defined(DART_PRECOMPILER)
current_relocations_ =
new (zone_) ZoneGrowableArray<Elf::Relocation>(zone_, 0);
current_symbols_ =
new (zone_) ZoneGrowableArray<Elf::SymbolData>(zone_, 0);
#endif
break;
case ProgramSection::Bss:
// The BSS section is pre-made in the Elf object for precompiled snapshots
// and unused otherwise, so there's no work that needs doing here.
return false;
case ProgramSection::BuildId:
// The GNU build ID is handled specially in the Elf object, and does not
// get used for non-precompiled snapshots.
return false;
}
intptr_t padding = current_section_stream_->Align(alignment);
if (alignment_padding != nullptr) {
*alignment_padding = padding;
}
return true;
}
void BlobImageWriter::ExitSection(ProgramSection name, bool vm, intptr_t size) {
#if defined(DART_PRECOMPILER)
ElfAddSection(elf_, name, SectionSymbol(name, vm), SectionLabel(name, vm),
current_section_stream_->buffer(), size, current_symbols_,
current_relocations_);
// We create the corresponding segment in the debugging information as well,
// since it needs the contents to create the correct build ID.
ElfAddSection(debug_elf_, name, SectionSymbol(name, vm),
SectionLabel(name, vm), current_section_stream_->buffer(), size,
current_symbols_, current_relocations_);
current_relocations_ = nullptr;
current_symbols_ = nullptr;
#endif
current_section_stream_ = nullptr;
}
intptr_t BlobImageWriter::WriteTargetWord(word value) {
current_section_stream_->WriteTargetWord(value);
return compiler::target::kWordSize;
}
intptr_t BlobImageWriter::Align(intptr_t alignment,
intptr_t offset,
intptr_t position) {
const intptr_t stream_padding =
current_section_stream_->Align(alignment, offset);
// Double-check that the position has the same alignment.
ASSERT_EQUAL(Utils::RoundUp(position, alignment, offset) - position,
stream_padding);
return stream_padding;
}
#if defined(DART_PRECOMPILER)
intptr_t BlobImageWriter::Relocation(intptr_t section_offset,
intptr_t source_label,
intptr_t source_offset,
intptr_t target_label,
intptr_t target_offset) {
ASSERT(FLAG_precompiled_mode);
current_relocations_->Add({compiler::target::kWordSize, section_offset,
source_label, source_offset, target_label,
target_offset});
// We write break instructions so it's easy to tell if a relocation doesn't
// get replaced appropriately.
return WriteTargetWord(kBreakInstructionFiller);
}
void BlobImageWriter::AddCodeSymbol(const Code& code,
const char* symbol,
intptr_t offset) {
const intptr_t label = next_label_++;
current_symbols_->Add({symbol, elf::STT_FUNC, offset, code.Size(), label});
if (elf_ != nullptr && elf_->dwarf() != nullptr) {
elf_->dwarf()->AddCode(code, label);
}
if (debug_elf_ != nullptr) {
debug_elf_->dwarf()->AddCode(code, label);
}
}
void BlobImageWriter::AddDataSymbol(const char* symbol,
intptr_t offset,
size_t size) {
if (!FLAG_add_readonly_data_symbols) return;
const intptr_t label = next_label_++;
current_symbols_->Add({symbol, elf::STT_OBJECT, offset, size, label});
}
#endif // defined(DART_PRECOMPILER)
#endif // !defined(DART_PRECOMPILED_RUNTIME)
ImageReader::ImageReader(const uint8_t* data_image,
const uint8_t* instructions_image)
: data_image_(ASSERT_NOTNULL(data_image)),
instructions_image_(ASSERT_NOTNULL(instructions_image)) {}
ApiErrorPtr ImageReader::VerifyAlignment() const {
if (!Utils::IsAligned(data_image_, kObjectStartAlignment) ||
!Utils::IsAligned(instructions_image_, kObjectStartAlignment)) {
return ApiError::New(
String::Handle(String::New("Snapshot is misaligned", Heap::kOld)),
Heap::kOld);
}
return ApiError::null();
}
#if defined(DART_PRECOMPILED_RUNTIME)
uword ImageReader::GetBareInstructionsAt(uint32_t offset) const {
ASSERT(Utils::IsAligned(offset, Instructions::kBarePayloadAlignment));
return reinterpret_cast<uword>(instructions_image_) + offset;
}
uword ImageReader::GetBareInstructionsEnd() const {
Image image(instructions_image_);
return reinterpret_cast<uword>(image.object_start()) + image.object_size();
}
#endif
InstructionsPtr ImageReader::GetInstructionsAt(uint32_t offset) const {
ASSERT(!FLAG_precompiled_mode);
ASSERT(Utils::IsAligned(offset, kObjectAlignment));
ObjectPtr result = UntaggedObject::FromAddr(
reinterpret_cast<uword>(instructions_image_) + offset);
ASSERT(result->IsInstructions());
ASSERT(result->untag()->IsMarked());
return Instructions::RawCast(result);
}
ObjectPtr ImageReader::GetObjectAt(uint32_t offset) const {
ASSERT(Utils::IsAligned(offset, kObjectAlignment));
ObjectPtr result =
UntaggedObject::FromAddr(reinterpret_cast<uword>(data_image_) + offset);
ASSERT(result->untag()->IsMarked());
return result;
}
} // namespace dart