// Copyright 2022 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.
#ifndef V8_WASM_MODULE_DECODER_IMPL_H_
#define V8_WASM_MODULE_DECODER_IMPL_H_
#if !V8_ENABLE_WEBASSEMBLY
#error This header should only be included if WebAssembly is enabled.
#endif // !V8_ENABLE_WEBASSEMBLY
#include "src/base/platform/wrappers.h"
#include "src/strings/unicode.h"
#include "src/utils/ostreams.h"
#include "src/wasm/canonical-types.h"
#include "src/wasm/constant-expression-interface.h"
#include "src/wasm/function-body-decoder-impl.h"
#include "src/wasm/module-decoder.h"
#include "src/wasm/wasm-module.h"
#include "src/wasm/wasm-subtyping.h"
#include "src/wasm/well-known-imports.h"
namespace v8::internal::wasm {
#define TRACE(...) \
do { \
if (v8_flags.trace_wasm_decoder) PrintF(__VA_ARGS__); \
} while (false)
inline const char* ExternalKindName(ImportExportKindCode kind) {
switch (kind) {
case kExternalFunction:
return "function";
case kExternalTable:
return "table";
case kExternalMemory:
return "memory";
case kExternalGlobal:
return "global";
case kExternalTag:
return "tag";
case kExternalExactFunction:
return "exact function";
}
return "unknown";
}
inline bool validate_utf8(Decoder* decoder, WireBytesRef string) {
// All callers call `consume_string()` first, which checks the length.
DCHECK_LE(string.length(), kV8MaxWasmStringLength);
return unibrow::Utf8::ValidateEncoding(
decoder->start() + decoder->GetBufferRelativeOffset(string.offset()),
string.length());
}
// Reads a length-prefixed string, checking that it is within bounds. Returns
// the offset of the string, and the length as an out parameter.
inline WireBytesRef consume_string(Decoder* decoder,
unibrow::Utf8Variant grammar,
const char* name, ITracer* tracer) {
if (tracer) {
tracer->Description(name);
tracer->Description(" ");
}
const uint8_t* length_start = decoder->pc();
uint32_t length = decoder->consume_u32v("length", tracer);
if (tracer) {
tracer->Description(": ");
tracer->Description(length);
tracer->NextLine();
}
if (V8_UNLIKELY(length > kV8MaxWasmStringLength)) {
decoder->errorf(length_start,
"Invalid string length %d, must be less than %d\n", length,
kV8MaxWasmStringLength);
}
uint32_t offset = decoder->pc_offset();
const uint8_t* string_start = decoder->pc();
// Consume bytes before validation to guarantee that the string is not oob.
if (length > 0) {
if (tracer) {
tracer->Bytes(decoder->pc(), length);
tracer->Description(name);
tracer->Description(": ");
tracer->Description(reinterpret_cast<const char*>(decoder->pc()), length);
tracer->NextLine();
}
decoder->consume_bytes(length, name);
if (decoder->ok()) {
switch (grammar) {
case unibrow::Utf8Variant::kLossyUtf8:
break;
case unibrow::Utf8Variant::kUtf8:
if (V8_UNLIKELY(
!unibrow::Utf8::ValidateEncoding(string_start, length))) {
decoder->errorf(string_start, "%s: no valid UTF-8 string", name);
}
break;
case unibrow::Utf8Variant::kWtf8:
if (V8_UNLIKELY(
!unibrow::Wtf8::ValidateEncoding(string_start, length))) {
decoder->errorf(string_start, "%s: no valid WTF-8 string", name);
}
break;
case unibrow::Utf8Variant::kUtf8NoTrap:
UNREACHABLE();
}
}
}
return {offset, decoder->failed() ? 0 : length};
}
inline WireBytesRef consume_string(Decoder* decoder,
unibrow::Utf8Variant grammar,
const char* name) {
return consume_string(decoder, grammar, name, ITracer::NoTrace);
}
inline WireBytesRef consume_utf8_string(Decoder* decoder, const char* name,
ITracer* tracer) {
return consume_string(decoder, unibrow::Utf8Variant::kUtf8, name, tracer);
}
inline SectionCode IdentifyUnknownSectionInternal(Decoder* decoder,
ITracer* tracer) {
WireBytesRef string = consume_utf8_string(decoder, "section name", tracer);
if (V8_UNLIKELY(decoder->failed())) {
return kUnknownSectionCode;
}
const uint8_t* section_name_start =
decoder->start() + decoder->GetBufferRelativeOffset(string.offset());
TRACE(" +%d section name : \"%.*s\"\n",
static_cast<int>(section_name_start - decoder->start()),
string.length() < 20 ? string.length() : 20, section_name_start);
using SpecialSectionPair = std::pair<base::Vector<const char>, SectionCode>;
static constexpr SpecialSectionPair kSpecialSections[]{
{base::StaticCharVector(kNameString), kNameSectionCode},
{base::StaticCharVector(kSourceMappingURLString),
kSourceMappingURLSectionCode},
{base::StaticCharVector(kInstTraceString), kInstTraceSectionCode},
{base::StaticCharVector(kBranchHintsString), kBranchHintsSectionCode},
{base::StaticCharVector(kCompilationPriorityString),
kCompilationPrioritySectionCode},
{base::StaticCharVector(kInstructionFrequenciesString),
kInstFrequenciesSectionCode},
{base::StaticCharVector(kCallTargetsString), kCallTargetsSectionCode},
{base::StaticCharVector(kDebugInfoString), kDebugInfoSectionCode},
{base::StaticCharVector(kExternalDebugInfoString),
kExternalDebugInfoSectionCode},
{base::StaticCharVector(kBuildIdString), kBuildIdSectionCode}};
auto name_vec = base::Vector<const char>::cast(
base::VectorOf(section_name_start, string.length()));
for (auto& special_section : kSpecialSections) {
if (name_vec == special_section.first) return special_section.second;
}
return kUnknownSectionCode;
}
// An iterator over the sections in a wasm binary module.
// Automatically skips all unknown sections.
class WasmSectionIterator {
public:
explicit WasmSectionIterator(Decoder* decoder, ITracer* tracer)
: decoder_(decoder),
tracer_(tracer),
section_code_(kUnknownSectionCode),
section_start_(decoder->pc()),
section_end_(decoder->pc()) {
next();
}
bool more() const { return decoder_->ok() && decoder_->more(); }
SectionCode section_code() const { return section_code_; }
const uint8_t* section_start() const { return section_start_; }
uint32_t section_length() const {
return static_cast<uint32_t>(section_end_ - section_start_);
}
base::Vector<const uint8_t> payload() const {
return {payload_start_, payload_length()};
}
const uint8_t* payload_start() const { return payload_start_; }
uint32_t payload_length() const {
return static_cast<uint32_t>(section_end_ - payload_start_);
}
// Advances to the next section, checking that decoding the current section
// stopped at {section_end_}.
void advance(bool move_to_section_end = false) {
if (move_to_section_end && decoder_->pc() < section_end_) {
decoder_->consume_bytes(
static_cast<uint32_t>(section_end_ - decoder_->pc()));
}
if (V8_UNLIKELY(decoder_->pc() != section_end_)) {
const char* msg = decoder_->pc() < section_end_ ? "shorter" : "longer";
decoder_->errorf(decoder_->pc(),
"section was %s than expected size "
"(%u bytes expected, %zu decoded)",
msg, section_length(),
static_cast<size_t>(decoder_->pc() - section_start_));
}
next();
}
private:
Decoder* decoder_;
ITracer* tracer_;
SectionCode section_code_;
const uint8_t* section_start_;
const uint8_t* payload_start_;
const uint8_t* section_end_;
// Reads the section code/name at the current position and sets up
// the embedder fields.
void next() {
if (!decoder_->more()) {
section_code_ = kUnknownSectionCode;
return;
}
section_start_ = decoder_->pc();
// Empty line before next section.
if (tracer_) tracer_->NextLine();
uint8_t section_code = decoder_->consume_u8("section kind", tracer_);
if (tracer_) {
tracer_->Description(": ");
tracer_->Description(SectionName(static_cast<SectionCode>(section_code)));
tracer_->NextLine();
}
// Read and check the section size.
uint32_t section_length = decoder_->consume_u32v("section length", tracer_);
if (tracer_) {
tracer_->Description(section_length);
tracer_->NextLine();
}
payload_start_ = decoder_->pc();
section_end_ = payload_start_ + section_length;
if (V8_UNLIKELY(section_length > decoder_->available_bytes())) {
decoder_->errorf(
section_start_,
"section (code %u, \"%s\") extends past end of the module "
"(length %u, remaining bytes %u)",
section_code, SectionName(static_cast<SectionCode>(section_code)),
section_length, decoder_->available_bytes());
section_end_ = payload_start_;
}
if (section_code == kUnknownSectionCode) {
// Check for known custom sections.
// To identify the unknown section we set the end of the decoder bytes to
// the end of the custom section, so that we do not read the section name
// beyond the end of the section.
const uint8_t* module_end = decoder_->end();
decoder_->set_end(section_end_);
section_code = IdentifyUnknownSectionInternal(decoder_, tracer_);
if (decoder_->ok()) decoder_->set_end(module_end);
// As a side effect, the above function will forward the decoder to after
// the identifier string.
payload_start_ = decoder_->pc();
} else if (V8_UNLIKELY(!IsValidSectionCode(section_code))) {
decoder_->errorf(decoder_->pc(), "unknown section code #0x%02x",
section_code);
}
section_code_ = decoder_->failed() ? kUnknownSectionCode
: static_cast<SectionCode>(section_code);
if (section_code_ == kUnknownSectionCode && section_end_ > decoder_->pc()) {
// Skip to the end of the unknown section.
uint32_t remaining = static_cast<uint32_t>(section_end_ - decoder_->pc());
decoder_->consume_bytes(remaining, "section payload", tracer_);
}
}
};
inline void DumpModule(const base::Vector<const uint8_t> module_bytes,
bool ok) {
std::string path;
if (v8_flags.dump_wasm_module_path) {
path = v8_flags.dump_wasm_module_path;
if (path.size() && !base::OS::isDirectorySeparator(path[path.size() - 1])) {
path += base::OS::DirectorySeparator();
}
}
// File are named `<hash>.{ok,failed}.wasm`.
// Limit the hash to 8 characters (32 bits).
uint32_t hash = static_cast<uint32_t>(GetWireBytesHash(module_bytes));
base::EmbeddedVector<char, 32> buf;
SNPrintF(buf, "%08x.%s.wasm", hash, ok ? "ok" : "failed");
path += buf.begin();
size_t rv = 0;
if (FILE* file = base::OS::FOpen(path.c_str(), "wb")) {
rv = fwrite(module_bytes.begin(), module_bytes.size(), 1, file);
base::Fclose(file);
}
if (rv != 1) {
OFStream os(stderr);
os << "Error while dumping wasm file to " << path << std::endl;
}
}
// The main logic for decoding the bytes of a module.
class ModuleDecoderImpl : public Decoder {
public:
ModuleDecoderImpl(WasmEnabledFeatures enabled_features,
base::Vector<const uint8_t> wire_bytes,
WasmDetectedFeatures* detected_features,
ITracer* tracer = ITracer::NoTrace)
: Decoder(wire_bytes),
enabled_features_(enabled_features),
detected_features_(detected_features),
module_(std::make_shared<WasmModule>()),
module_start_(wire_bytes.begin()),
module_end_(wire_bytes.end()),
tracer_(tracer) {}
void onFirstError() override {
pc_ = end_; // On error, terminate section decoding loop.
}
void DecodeModuleHeader(base::Vector<const uint8_t> bytes) {
if (V8_UNLIKELY(failed())) return;
Reset(bytes);
const uint8_t* pos = pc_;
uint32_t magic_word = consume_u32("wasm magic", tracer_);
if (tracer_) tracer_->NextLine();
#define BYTES(x) (x & 0xFF), (x >> 8) & 0xFF, (x >> 16) & 0xFF, (x >> 24) & 0xFF
if (V8_UNLIKELY(magic_word != kWasmMagic)) {
errorf(pos,
"expected magic word %02x %02x %02x %02x, "
"found %02x %02x %02x %02x",
BYTES(kWasmMagic), BYTES(magic_word));
}
pos = pc_;
{
uint32_t magic_version = consume_u32("wasm version", tracer_);
if (tracer_) tracer_->NextLine();
if (V8_UNLIKELY(magic_version != kWasmVersion)) {
errorf(pos,
"expected version %02x %02x %02x %02x, "
"found %02x %02x %02x %02x",
BYTES(kWasmVersion), BYTES(magic_version));
}
}
#undef BYTES
}
bool CheckSectionOrder(SectionCode section_code) {
// Check the order of ordered sections.
if (section_code >= kFirstSectionInModule &&
section_code < kFirstUnorderedSection) {
if (V8_UNLIKELY(section_code < next_ordered_section_)) {
errorf(pc(), "unexpected section <%s>", SectionName(section_code));
return false;
}
next_ordered_section_ = section_code + 1;
return true;
}
// Ignore ordering problems in unknown / custom sections. Even allow them to
// appear multiple times. As optional sections we use them on a "best
// effort" basis.
if (section_code == kUnknownSectionCode) return true;
if (section_code > kLastKnownModuleSection) return true;
// The rest is standardized unordered sections; they are checked more
// thoroughly..
DCHECK_LE(kFirstUnorderedSection, section_code);
DCHECK_GE(kLastKnownModuleSection, section_code);
// Check that unordered sections don't appear multiple times.
if (V8_UNLIKELY(has_seen_unordered_section(section_code))) {
errorf(pc(), "Multiple %s sections not allowed",
SectionName(section_code));
return false;
}
set_seen_unordered_section(section_code);
// Define a helper to ensure that sections <= {before} appear before the
// current unordered section, and everything >= {after} appears after it.
auto check_order = [this, section_code](SectionCode before,
SectionCode after) -> bool {
DCHECK_LT(before, after);
if (V8_UNLIKELY(next_ordered_section_ > after)) {
errorf(pc(), "The %s section must appear before the %s section",
SectionName(section_code), SectionName(after));
return false;
}
if (next_ordered_section_ <= before) next_ordered_section_ = before + 1;
return true;
};
// Now check the ordering constraints of specific unordered sections.
switch (section_code) {
case kDataCountSectionCode:
return check_order(kElementSectionCode, kCodeSectionCode);
case kTagSectionCode:
return check_order(kMemorySectionCode, kGlobalSectionCode);
case kStringRefSectionCode:
// TODO(12868): If there's a tag section, assert that we're after the
// tag section.
return check_order(kMemorySectionCode, kGlobalSectionCode);
case kInstTraceSectionCode:
// Custom section following code.metadata tool convention containing
// offsets specifying where trace marks should be emitted.
// Be lenient with placement of instruction trace section. All except
// first occurrence after function section and before code section are
// ignored.
return true;
default:
return true;
}
}
void DecodeSection(SectionCode section_code,
base::Vector<const uint8_t> bytes, uint32_t offset) {
if (V8_UNLIKELY(failed())) return;
Reset(bytes, offset);
TRACE("Section: %s\n", SectionName(section_code));
TRACE("Decode Section %p - %p\n", bytes.begin(), bytes.end());
if (!CheckSectionOrder(section_code)) return;
switch (section_code) {
case kUnknownSectionCode:
break;
case kTypeSectionCode:
DecodeTypeSection();
break;
case kImportSectionCode:
DecodeImportSection();
break;
case kFunctionSectionCode:
DecodeFunctionSection();
break;
case kTableSectionCode:
DecodeTableSection();
break;
case kMemorySectionCode:
DecodeMemorySection();
break;
case kGlobalSectionCode:
DecodeGlobalSection();
break;
case kExportSectionCode:
DecodeExportSection();
break;
case kStartSectionCode:
DecodeStartSection();
break;
case kCodeSectionCode:
DecodeCodeSection();
break;
case kElementSectionCode:
DecodeElementSection();
break;
case kDataSectionCode:
DecodeDataSection();
break;
case kNameSectionCode:
DecodeNameSection();
break;
case kSourceMappingURLSectionCode:
DecodeSourceMappingURLSection();
break;
case kDebugInfoSectionCode:
module_->debug_symbols[WasmDebugSymbols::Type::EmbeddedDWARF] = {
WasmDebugSymbols::Type::EmbeddedDWARF, {}};
consume_bytes(static_cast<uint32_t>(end_ - start_), ".debug_info");
break;
case kExternalDebugInfoSectionCode:
DecodeExternalDebugInfoSection();
break;
case kBuildIdSectionCode:
DecodeBuildIdSection();
break;
case kInstTraceSectionCode:
if (enabled_features_.has_instruction_tracing()) {
DecodeInstTraceSection();
} else {
// Ignore this section when feature is disabled. It is an optional
// custom section anyways.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
break;
case kBranchHintsSectionCode:
DecodeBranchHintsSection();
break;
case kCompilationPrioritySectionCode:
if (enabled_features_.has_compilation_hints()) {
DecodeCompilationPrioritySection();
} else {
// Ignore this section when feature was disabled. It is an optional
// custom section anyways.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
break;
case kInstFrequenciesSectionCode:
if (enabled_features_.has_compilation_hints()) {
DecodeInstructionFrequenciesSection();
} else {
// Ignore this section when feature was disabled. It is an optional
// custom section anyways.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
break;
case kCallTargetsSectionCode:
if (enabled_features_.has_compilation_hints()) {
DecodeCallTargetsSection();
} else {
// Ignore this section when feature was disabled. It is an optional
// custom section anyways.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
break;
case kDataCountSectionCode:
DecodeDataCountSection();
break;
case kTagSectionCode:
DecodeTagSection();
break;
case kStringRefSectionCode:
if (enabled_features_.has_stringref()) {
DecodeStringRefSection();
} else {
errorf(pc(), "unexpected section <%s> (enable with --wasm-stringref)",
SectionName(section_code));
}
break;
default:
errorf(pc(), "unexpected section <%s>", SectionName(section_code));
return;
}
if (V8_UNLIKELY(pc() != bytes.end())) {
const char* msg = pc() < bytes.end() ? "shorter" : "longer";
errorf(pc(),
"section was %s than expected size "
"(%zu bytes expected, %zu decoded)",
msg, bytes.size(), static_cast<size_t>(pc() - bytes.begin()));
}
}
static constexpr const char* TypeKindName(uint8_t kind) {
switch (kind) {
// clang-format off
case kWasmFunctionTypeCode: return "func";
case kWasmStructTypeCode: return "struct";
case kWasmArrayTypeCode: return "array";
case kWasmContTypeCode: return "cont";
default: return "unknown";
// clang-format on
}
}
TypeDefinition consume_base_type_definition(bool is_descriptor,
SharedFlag is_shared) {
const bool is_final = true;
uint8_t kind = consume_u8(" kind", tracer_);
if (tracer_) {
tracer_->Description(": ");
tracer_->Description(TypeKindName(kind));
}
switch (kind) {
case kWasmFunctionTypeCode: {
const FunctionSig* sig = consume_sig();
if (V8_UNLIKELY(sig == nullptr)) {
CHECK(!ok());
return {};
}
return {sig, kNoSuperType, is_final, is_shared};
}
case kWasmStructTypeCode: {
module_->is_wasm_gc = true;
const StructType* type = consume_struct(is_descriptor, is_shared);
if (V8_UNLIKELY(type == nullptr)) {
CHECK(!ok());
return {};
}
return {type, kNoSuperType, is_final, is_shared};
}
case kWasmArrayTypeCode: {
module_->is_wasm_gc = true;
const ArrayType* type = consume_array();
if (V8_UNLIKELY(type == nullptr)) {
CHECK(!ok());
return {};
}
return {type, kNoSuperType, is_final, is_shared};
}
case kWasmContTypeCode: {
if (V8_UNLIKELY(!enabled_features_.has_wasmfx())) {
error(pc() - 1,
"core stack switching not enabled (enable with --wasm-wasmfx)");
return {};
}
const uint8_t* pos = pc();
HeapType hp = consume_heap_type();
if (V8_UNLIKELY(!hp.has_index())) {
error(pos, "cont type must refer to a signature index");
return {};
}
ContType* type =
module_->signature_storage.New<ContType>(hp.ref_index());
return {type, kNoSuperType, is_final, is_shared};
}
default:
if (tracer_) tracer_->NextLine();
errorf(pc() - 1, "unknown type form: %d", kind);
return {};
}
}
TypeDefinition consume_described_type(bool is_descriptor,
SharedFlag is_shared) {
uint8_t kind = read_u8<Decoder::FullValidationTag>(pc(), "type kind");
if (kind == kWasmDescriptorCode) {
if (V8_UNLIKELY(!enabled_features_.has_custom_descriptors())) {
error(pc(), "descriptor types need --wasm-custom-descriptors");
return {};
}
detected_features_->add_custom_descriptors();
consume_bytes(1, "", tracer_);
const uint8_t* pos = pc();
uint32_t descriptor = consume_u32v(" descriptor", tracer_);
if (V8_UNLIKELY(descriptor >= module_->types.size())) {
errorf(pos, "descriptor type index %u is out of bounds", descriptor);
return {};
}
if (tracer_) tracer_->Description(descriptor);
if (tracer_) tracer_->NextLine();
TypeDefinition type =
consume_base_type_definition(is_descriptor, is_shared);
if (V8_UNLIKELY(type.kind != TypeDefinition::kStruct)) {
error(pos - 1, "'descriptor' may only be used with structs");
return {};
}
type.descriptor = ModuleTypeIndex{descriptor};
return type;
} else {
return consume_base_type_definition(is_descriptor, is_shared);
}
}
TypeDefinition consume_describing_type(size_t current_type_index,
SharedFlag is_shared) {
uint8_t kind = read_u8<Decoder::FullValidationTag>(pc(), "type kind");
if (kind == kWasmDescribesCode) {
if (V8_UNLIKELY(!enabled_features_.has_custom_descriptors())) {
error(pc(), "descriptor types need --wasm-custom-descriptors");
return {};
}
detected_features_->add_custom_descriptors();
consume_bytes(1, "", tracer_);
const uint8_t* pos = pc();
uint32_t describes = consume_u32v(" describes", tracer_);
if (V8_UNLIKELY(describes >= current_type_index)) {
error(pos, "types can only describe previously-declared types");
return {};
}
if (tracer_) tracer_->Description(describes);
if (tracer_) tracer_->NextLine();
TypeDefinition type = consume_described_type(true, is_shared);
if (V8_UNLIKELY(type.kind != TypeDefinition::kStruct)) {
error(pos - 1, "'describes' may only be used with structs");
return {};
}
type.describes = ModuleTypeIndex{describes};
return type;
} else {
return consume_described_type(false, is_shared);
}
}
TypeDefinition consume_shared_type(size_t current_type_index) {
uint8_t kind = read_u8<Decoder::FullValidationTag>(pc(), "type kind");
if (kind == kSharedFlagCode) {
if (V8_UNLIKELY(!enabled_features_.has_shared())) {
errorf(pc() - 1, "unknown type form: %d, enable with --wasm-shared",
kind);
return {};
}
module_->has_shared_part = true;
consume_bytes(1, " shared", tracer_);
TypeDefinition type =
consume_describing_type(current_type_index, SharedFlag{true});
DCHECK(type.is_shared || failed());
if (V8_UNLIKELY(type.kind == TypeDefinition::kFunction ||
type.kind == TypeDefinition::kCont)) {
// TODO(42204563): Support shared functions/continuations.
error(pc() - 1, "shared functions/continuations are not supported yet");
return {};
}
return type;
} else {
return consume_describing_type(current_type_index, SharedFlag{false});
}
}
// {current_type_index} is the index of the type that's being decoded.
// Any supertype must have a lower index.
TypeDefinition consume_subtype_definition(size_t current_type_index) {
uint8_t kind = read_u8<Decoder::FullValidationTag>(pc(), "type kind");
if (kind == kWasmSubtypeCode || kind == kWasmSubtypeFinalCode) {
module_->is_wasm_gc = true;
bool is_final = kind == kWasmSubtypeFinalCode;
consume_bytes(1, is_final ? " subtype final, " : " subtype extensible, ",
tracer_);
constexpr uint32_t kMaximumSupertypes = 1;
uint32_t supertype_count =
consume_count("supertype count", kMaximumSupertypes);
uint32_t supertype = kNoSuperType.index;
if (supertype_count == 1) {
supertype = consume_u32v("supertype", tracer_);
if (V8_UNLIKELY(supertype >= current_type_index)) {
errorf("type %u: invalid supertype %u", current_type_index,
supertype);
return {};
}
if (tracer_) {
tracer_->Description(supertype);
tracer_->NextLine();
}
}
TypeDefinition type = consume_shared_type(current_type_index);
type.supertype = ModuleTypeIndex{supertype};
type.is_final = is_final;
return type;
} else {
return consume_shared_type(current_type_index);
}
}
void DecodeTypeSection() {
TypeCanonicalizer* type_canon = GetTypeCanonicalizer();
uint32_t types_count = consume_count("types count", kV8MaxWasmTypes);
for (uint32_t i = 0; ok() && i < types_count; ++i) {
TRACE("DecodeType[%d] module+%d\n", i, static_cast<int>(pc_ - start_));
uint8_t kind = read_u8<Decoder::FullValidationTag>(pc(), "type kind");
size_t initial_size = module_->types.size();
uint32_t group_size = 1;
if (kind == kWasmRecursiveTypeGroupCode) {
module_->is_wasm_gc = true;
uint32_t rec_group_offset = pc_offset();
consume_bytes(1, "rec. group definition", tracer_);
if (tracer_) tracer_->NextLine();
group_size = consume_count("recursive group size", kV8MaxWasmTypes);
if (tracer_) tracer_->RecGroupOffset(rec_group_offset, group_size);
}
if (V8_UNLIKELY(initial_size + group_size > kV8MaxWasmTypes)) {
errorf(pc(), "Type definition count exceeds maximum %zu",
kV8MaxWasmTypes);
return;
}
// We need to resize types before decoding the type definitions in this
// group, so that the correct type size is visible to type definitions.
module_->types.resize(initial_size + group_size);
for (uint32_t j = 0; j < group_size; j++) {
if (tracer_) tracer_->TypeOffset(pc_offset());
TypeDefinition type = consume_subtype_definition(initial_size + j);
if (V8_UNLIKELY(failed())) return;
module_->types[initial_size + j] = type;
}
FinalizeRecgroup(group_size, type_canon);
if (kind == kWasmRecursiveTypeGroupCode && tracer_) {
tracer_->Description("end of rec. group");
tracer_->NextLine();
}
}
}
void FinalizeRecgroup(uint32_t group_size, TypeCanonicalizer* type_canon) {
// Now that we have decoded the entire recgroup, check its validity,
// initialize additional data, and canonicalize it:
// - check supertype validity
// - propagate subtyping depths
// - validate is_shared bits and set up RefTypeKind fields
WasmModule* module = module_.get();
uint32_t end_index = static_cast<uint32_t>(module->types.size());
uint32_t start_index = end_index - group_size;
for (uint32_t i = start_index; ok() && i < end_index; ++i) {
TypeDefinition& type_def = module_->types[i];
SharedFlag is_shared = type_def.is_shared;
switch (type_def.kind) {
case TypeDefinition::kFunction: {
base::Vector<const ValueType> all = type_def.function_sig->all();
size_t count = all.size();
ValueType* storage = const_cast<ValueType*>(all.begin());
for (uint32_t j = 0; j < count; j++) {
value_type_reader::Populate(&storage[j], module);
ValueType type = storage[j];
if (V8_UNLIKELY(is_shared && !type.is_shared())) {
DCHECK(enabled_features_.has_shared());
uint32_t retcount =
static_cast<uint32_t>(type_def.function_sig->return_count());
const char* param_or_return =
j < retcount ? "return" : "parameter";
uint32_t index = j < retcount ? j : j - retcount;
// {pc_} isn't very accurate, it's pointing at the end of the
// recgroup. So to ease debugging, we print the type's index.
errorf(pc_,
"Type %u: shared signature must have shared %s types, "
"actual type for %s %d is %s",
i, param_or_return, param_or_return, index,
type.name().c_str());
return;
}
}
break;
}
case TypeDefinition::kStruct: {
size_t count = type_def.struct_type->field_count();
ValueType* storage =
const_cast<ValueType*>(type_def.struct_type->fields().begin());
for (uint32_t j = 0; j < count; j++) {
value_type_reader::Populate(&storage[j], module);
ValueType type = storage[j];
if (V8_UNLIKELY(is_shared && !type.is_shared())) {
errorf(pc_,
"Type %u: shared struct must have shared field types, "
"actual type for field %d is %s",
i, j, type.name().c_str());
return;
}
}
if (type_def.descriptor.valid()) {
const TypeDefinition& descriptor =
module->type(type_def.descriptor);
if (V8_UNLIKELY(descriptor.describes.index != i)) {
uint32_t d = type_def.descriptor.index;
errorf(pc_,
"Type %u has descriptor %u but %u doesn't describe %u", i,
d, d, i);
return;
}
if (V8_UNLIKELY(descriptor.is_shared != type_def.is_shared)) {
errorf(pc_,
"Type %u and its descriptor %u must have same sharedness",
i, type_def.descriptor.index);
return;
}
if (V8_UNLIKELY(descriptor.is_final != type_def.is_final)) {
errorf(pc_,
"Type %u and its descriptor %u must have same finality", i,
type_def.descriptor.index);
return;
}
}
if (type_def.describes.valid()) {
if (V8_UNLIKELY(module->type(type_def.describes).descriptor.index !=
i)) {
uint32_t d = type_def.describes.index;
errorf(pc_,
"Type %u describes %u but %u isn't a descriptor for %u", i,
d, d, i);
return;
}
}
break;
}
case TypeDefinition::kArray: {
value_type_reader::Populate(
const_cast<ArrayType*>(type_def.array_type)
->element_type_writable_ptr(),
module);
ValueType type = type_def.array_type->element_type();
if (V8_UNLIKELY(is_shared && !type.is_shared())) {
errorf(pc_,
"Type %u: shared array must have shared element type, "
"actual element type is %s",
i, type.name().c_str());
return;
}
break;
}
case TypeDefinition::kCont: {
ModuleTypeIndex contfun_typeid =
type_def.cont_type->contfun_typeindex();
const TypeDefinition contfun_type =
module_->types[contfun_typeid.index];
if (V8_UNLIKELY(contfun_type.kind != TypeDefinition::kFunction)) {
errorf(pc_,
"Type %u: cont type must refer to a signature index, "
"actual type is %s",
i, module_->heap_type(contfun_typeid).name().c_str());
return;
}
if (V8_UNLIKELY(is_shared && !contfun_type.is_shared)) {
errorf(pc_,
"Type %u: shared cont type must refer to a shared signature,"
" actual type is %s",
module_->heap_type(contfun_typeid).name().c_str());
return;
}
break;
}
}
}
module->isorecursive_canonical_type_ids.resize(end_index);
type_canon->AddRecursiveGroup(module, group_size);
for (uint32_t i = start_index; ok() && i < end_index; ++i) {
TypeDefinition& type_def = module_->types[i];
ModuleTypeIndex explicit_super = type_def.supertype;
if (!explicit_super.valid()) continue; // No supertype.
DCHECK_LT(explicit_super.index, i); // Checked during decoding.
uint32_t depth = module->type(explicit_super).subtyping_depth + 1;
type_def.subtyping_depth = depth;
DCHECK_GE(depth, 0);
if (V8_UNLIKELY(depth > kV8MaxRttSubtypingDepth)) {
errorf("type %u: subtyping depth is greater than allowed", i);
return;
}
// This check is technically redundant; we include for the improved error
// message.
if (V8_UNLIKELY(module->type(explicit_super).is_final)) {
errorf("type %u extends final type %u", i, explicit_super.index);
return;
}
if (V8_UNLIKELY(!ValidSubtypeDefinition(ModuleTypeIndex{i},
explicit_super, module))) {
errorf("type %u has invalid explicit supertype %u", i,
explicit_super.index);
return;
}
}
}
uint32_t GetImportGroupCount(bool is_compact_encoding_by_type) {
uint32_t count = is_compact_encoding_by_type
? consume_count("count", kV8MaxWasmImports)
: 1;
if (V8_UNLIKELY(module_->import_table.size() + count > kV8MaxWasmImports)) {
errorf(pc_, "Exceeding maximum number of imports (%u)",
kV8MaxWasmImports);
return 0;
}
// We don't know the cumulative size of import groups up front. Usually,
// a std::vector's exponential growth behavior should do a good job;
// in case of very large import groups we can help it with an explicit
// reservation.
std::vector<WasmImport>& table = module_->import_table;
if (count > table.capacity()) {
table.reserve(table.capacity() + count);
}
return count;
}
WasmImport* AddImport(WireBytesRef module_name, WireBytesRef field_name,
ImportExportKindCode kind,
bool is_compact_encoding_by_type) {
if (tracer_ && is_compact_encoding_by_type) {
tracer_->ImportOffset(pc_offset());
}
WireBytesRef name = is_compact_encoding_by_type
? consume_utf8_string(this, "field name", tracer_)
: field_name;
module_->import_table.push_back(WasmImport{
.module_name = module_name, .field_name = name, .kind = kind});
return &module_->import_table.back();
}
void DecodeSingleOrGroupImport(WireBytesRef module_name,
WireBytesRef field_name,
ImportExportKindCode kind,
bool is_compact_encoding_by_type) {
if (tracer_) {
tracer_->Description(": ");
tracer_->Description(ExternalKindName(kind));
}
switch (kind) {
case kExternalFunction:
case kExternalExactFunction: {
// ===== Imported function ===========================================
if (V8_UNLIKELY(kind == kExternalExactFunction &&
!enabled_features_.has_custom_descriptors())) {
errorf(
pc_ - 1,
"Invalid import kind %d, enable with --wasm-custom-descriptors",
kind);
break;
}
const FunctionSig* sig;
ModuleTypeIndex sig_index = consume_sig_index(module_.get(), &sig);
uint32_t count = GetImportGroupCount(is_compact_encoding_by_type);
for (uint32_t i = 0; ok() && i < count; ++i) {
WasmImport* import = AddImport(module_name, field_name, kind,
is_compact_encoding_by_type);
import->index = static_cast<uint32_t>(module_->functions.size());
module_->num_imported_functions++;
module_->functions.push_back(WasmFunction{
.sig = sig,
.func_index = import->index,
.sig_index = sig_index,
.imported = true,
});
if (kind == kExternalExactFunction) {
module_->functions.back().exact = true;
detected_features_->add_custom_descriptors();
}
}
break;
}
case kExternalTable: {
// ===== Imported table ==============================================
const uint8_t* type_position = pc();
ValueType type = consume_value_type(module_.get());
if (V8_UNLIKELY(!type.is_ref())) {
errorf(type_position, "Invalid table type %s", type.name().c_str());
break;
}
WasmTable table_template{.type = type, .imported = true};
const uint32_t start_table_import_index =
static_cast<uint32_t>(module_->tables.size());
consume_table_flags(&table_template);
DCHECK_IMPLIES(table_template.shared,
enabled_features_.has_shared() || !ok());
if (table_template.shared && enabled_features_.has_shared()) {
module_->has_shared_part = true;
if (V8_UNLIKELY(!type.is_shared())) {
errorf(type_position,
"Shared table %i must have shared element type, actual "
"type %s",
start_table_import_index, type.name().c_str());
return;
}
}
uint64_t kNoMaximum = kMaxUInt64;
consume_resizable_limits(
"table", "elements", wasm::max_table_size(),
&table_template.initial_size, table_template.has_maximum_size,
kNoMaximum, &table_template.maximum_size,
table_template.is_table64() ? k64BitLimits : k32BitLimits);
uint32_t count = GetImportGroupCount(is_compact_encoding_by_type);
for (uint32_t i = 0; ok() && i < count; ++i) {
WasmImport* import = AddImport(module_name, field_name, kind,
is_compact_encoding_by_type);
import->index = static_cast<uint32_t>(module_->tables.size());
module_->num_imported_tables++;
module_->tables.push_back(table_template);
}
break;
}
case kExternalMemory: {
// ===== Imported memory =============================================
WasmMemory memory_template;
consume_memory_flags(&memory_template);
uint32_t max_pages = memory_template.is_memory64()
? kSpecMaxMemory64Pages
: kSpecMaxMemory32Pages;
consume_resizable_limits(
"memory", "pages", max_pages, &memory_template.initial_pages,
memory_template.has_maximum_pages, max_pages,
&memory_template.maximum_pages,
memory_template.is_memory64() ? k64BitLimits : k32BitLimits);
uint32_t count = GetImportGroupCount(is_compact_encoding_by_type);
static_assert(kV8MaxWasmMemories <= kMaxUInt32);
if (V8_UNLIKELY(module_->memories.size() + count >
kV8MaxWasmMemories)) {
errorf(pc_, "At most %u imported memories are supported",
kV8MaxWasmMemories);
break;
}
for (uint32_t i = 0; ok() && i < count; ++i) {
WasmImport* import = AddImport(module_name, field_name, kind,
is_compact_encoding_by_type);
uint32_t mem_index = static_cast<uint32_t>(module_->memories.size());
import->index = mem_index;
module_->memories.push_back(memory_template);
WasmMemory* memory = &module_->memories.back();
memory->index = mem_index;
memory->imported = true;
}
break;
}
case kExternalGlobal: {
// ===== Imported global =============================================
ValueType type = consume_value_type(module_.get());
auto [mutability, shared] = consume_global_flags();
if (V8_UNLIKELY(failed())) break;
if (V8_UNLIKELY(shared && !type.is_shared())) {
error("shared imported global must have shared type");
break;
}
uint32_t count = GetImportGroupCount(is_compact_encoding_by_type);
for (uint32_t i = 0; ok() && i < count; ++i) {
WasmImport* import = AddImport(module_name, field_name, kind,
is_compact_encoding_by_type);
import->index = static_cast<uint32_t>(module_->globals.size());
module_->globals.push_back(WasmGlobal{
.type = type,
.mutability = mutability,
.index_in_buffer = 0, // set later in CalculateGlobalOffsets
.shared = shared,
.imported = true});
module_->num_imported_globals++;
if (shared) module_->has_shared_part = true;
if (mutability) module_->num_imported_mutable_globals++;
if (tracer_) tracer_->NextLine();
}
break;
}
case kExternalTag: {
// ===== Imported tag ================================================
const WasmTagSig* tag_sig = nullptr;
consume_exception_attribute(); // Attribute ignored for now.
ModuleTypeIndex sig_index =
consume_tag_sig_index(module_.get(), &tag_sig);
uint32_t count = GetImportGroupCount(is_compact_encoding_by_type);
for (uint32_t i = 0; ok() && i < count; ++i) {
WasmImport* import = AddImport(module_name, field_name, kind,
is_compact_encoding_by_type);
import->index = static_cast<uint32_t>(module_->tags.size());
module_->num_imported_tags++;
module_->tags.emplace_back(tag_sig, sig_index);
}
break;
}
default:
errorf(pc_, "unknown import kind 0x%02x", kind);
break;
}
}
void DecodeImportSection() {
uint32_t import_table_count =
consume_count("imports count", kV8MaxWasmImports);
for (uint32_t i = 0; ok() && i < import_table_count; ++i) {
TRACE("DecodeImportTable[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
const uint32_t start_offset = pc_offset();
WireBytesRef module_name =
consume_utf8_string(this, "module name", tracer_);
WireBytesRef field_name =
consume_utf8_string(this, "field name", tracer_);
uint8_t kind = consume_u8("kind or compact flag", tracer_);
if (kind == kCompactImportByModule && field_name.length() == 0) {
if (V8_UNLIKELY(!enabled_features_.has_compact_imports())) {
errorf(pc_ - 1,
"Invalid import kind %d, enable with --wasm-compact-imports",
kind);
break;
}
uint32_t compact_import_table_count =
consume_count("compact_imports_1 count", kV8MaxWasmImports);
for (uint32_t ic = 0; ok() && ic < compact_import_table_count; ++ic) {
if (tracer_) tracer_->ImportOffset(pc_offset());
WireBytesRef field_name_compact =
consume_utf8_string(this, "field name", tracer_);
ImportExportKindCode kind_compact =
static_cast<ImportExportKindCode>(consume_u8("kind", tracer_));
DecodeSingleOrGroupImport(module_name, field_name_compact,
kind_compact, false);
}
} else if (kind == kCompactImportByModuleAndType &&
field_name.length() == 0) {
if (V8_UNLIKELY(!enabled_features_.has_compact_imports())) {
errorf(pc_ - 1,
"Invalid import kind %d, enable with --wasm-compact-imports",
kind);
break;
}
ImportExportKindCode kind_compact =
static_cast<ImportExportKindCode>(consume_u8("kind", tracer_));
DecodeSingleOrGroupImport(module_name, WireBytesRef(), kind_compact,
true);
} else {
// Process uncompacted import format
DecodeSingleOrGroupImport(module_name, field_name,
static_cast<ImportExportKindCode>(kind),
false);
if (tracer_) {
// TODO(491514514) this is still not really correct in the hexdump
// output. Will print "Import #" at the end of the import,
// not at the start.
tracer_->ImportOffset(start_offset);
}
}
}
if (module_->memories.size() > 1) {
detected_features_->add_multi_memory();
}
if (module_->num_imported_mutable_globals > 0) {
detected_features_->add_mutable_globals();
}
UpdateComputedMemoryInformation();
module_->type_feedback.well_known_imports.Initialize(
module_->num_imported_functions);
if (tracer_) tracer_->ImportsDone(module_.get());
}
void DecodeFunctionSection() {
uint32_t functions_count =
consume_count("functions count", v8_flags.max_wasm_functions);
DCHECK_EQ(module_->functions.size(), module_->num_imported_functions);
uint32_t total_function_count =
module_->num_imported_functions + functions_count;
module_->functions.resize(total_function_count);
module_->num_declared_functions = functions_count;
for (uint32_t func_index = module_->num_imported_functions;
func_index < total_function_count; ++func_index) {
WasmFunction* function = &module_->functions[func_index];
function->func_index = func_index;
if (tracer_) tracer_->FunctionName(func_index);
function->sig_index = consume_sig_index(module_.get(), &function->sig);
if (V8_UNLIKELY(!ok())) return;
}
}
void DecodeTableSection() {
static_assert(kV8MaxWasmTables <= kMaxUInt32);
uint32_t table_count = consume_count("table count", kV8MaxWasmTables);
for (uint32_t i = 0; ok() && i < table_count; i++) {
if (tracer_) tracer_->TableOffset(pc_offset());
module_->tables.emplace_back();
WasmTable* table = &module_->tables.back();
const uint8_t* type_position = pc();
bool has_initializer = false;
if (read_u8<Decoder::FullValidationTag>(
pc(), "table-with-initializer byte") == 0x40) {
consume_bytes(1, "with-initializer ", tracer_);
has_initializer = true;
type_position++;
uint8_t reserved = consume_u8("reserved-byte", tracer_);
if (V8_UNLIKELY(reserved != 0)) {
error(type_position, "Reserved byte must be 0x00");
break;
}
type_position++;
}
ValueType table_type = consume_value_type(module_.get());
if (V8_UNLIKELY(!table_type.is_ref())) {
error(type_position, "Only reference types can be used as table types");
break;
}
if (V8_UNLIKELY(!has_initializer && !table_type.is_defaultable())) {
errorf(type_position,
"Table of non-defaultable table %s needs initial value",
table_type.name().c_str());
break;
}
table->type = table_type;
consume_table_flags(table);
DCHECK_IMPLIES(table->shared, enabled_features_.has_shared() || !ok());
if (table->shared && enabled_features_.has_shared()) {
module_->has_shared_part = true;
if (V8_UNLIKELY(!table_type.is_shared())) {
errorf(
type_position,
"Shared table %i must have shared element type, actual type %s",
i + module_->num_imported_tables, table_type.name().c_str());
break;
}
}
// Note that we should not throw an error if the declared maximum size is
// oob. We will instead fail when growing at runtime.
uint64_t kNoMaximum = kMaxUInt64;
consume_resizable_limits(
"table", "elements", wasm::max_table_size(), &table->initial_size,
table->has_maximum_size, kNoMaximum, &table->maximum_size,
table->is_table64() ? k64BitLimits : k32BitLimits);
if (has_initializer) {
table->initial_value = consume_init_expr(module_.get(), table_type);
}
}
}
void DecodeMemorySection() {
const uint8_t* mem_count_pc = pc();
static_assert(kV8MaxWasmMemories <= kMaxUInt32);
// Use {kV8MaxWasmMemories} here, but only allow for >1 memory if
// multi-memory is enabled (checked below). This allows for better error
// messages.
uint32_t memory_count = consume_count("memory count", kV8MaxWasmMemories);
size_t imported_memories = module_->memories.size();
DCHECK_GE(kV8MaxWasmMemories, imported_memories);
if (V8_UNLIKELY(memory_count > kV8MaxWasmMemories - imported_memories)) {
errorf(mem_count_pc,
"Exceeding maximum number of memories (%u; declared %u, "
"imported %zu)",
kV8MaxWasmMemories, memory_count, imported_memories);
}
module_->memories.resize(imported_memories + memory_count);
for (uint32_t i = 0; ok() && i < memory_count; i++) {
WasmMemory* memory = module_->memories.data() + imported_memories + i;
memory->index = static_cast<uint32_t>(imported_memories + i);
if (tracer_) tracer_->MemoryOffset(pc_offset());
consume_memory_flags(memory);
uint32_t max_pages =
memory->is_memory64() ? kSpecMaxMemory64Pages : kSpecMaxMemory32Pages;
consume_resizable_limits(
"memory", "pages", max_pages, &memory->initial_pages,
memory->has_maximum_pages, max_pages, &memory->maximum_pages,
memory->is_memory64() ? k64BitLimits : k32BitLimits);
}
if (module_->memories.size() > 1) {
detected_features_->add_multi_memory();
}
UpdateComputedMemoryInformation();
}
void UpdateComputedMemoryInformation() {
for (WasmMemory& memory : module_->memories) {
UpdateComputedInformation(&memory);
}
}
void DecodeGlobalSection() {
uint32_t globals_count = consume_count("globals count", kV8MaxWasmGlobals);
uint32_t imported_globals = static_cast<uint32_t>(module_->globals.size());
// It is important to not resize the globals vector from the beginning,
// because we use its current size when decoding the initializer.
module_->globals.reserve(imported_globals + globals_count);
for (uint32_t i = 0; ok() && i < globals_count; ++i) {
TRACE("DecodeGlobal[%d] module+%d\n", i, static_cast<int>(pc_ - start_));
if (tracer_) tracer_->GlobalOffset(pc_offset());
const uint8_t* pos = pc_;
ValueType type = consume_value_type(module_.get());
auto [mutability, shared] = consume_global_flags();
if (V8_UNLIKELY(failed())) return;
if (V8_UNLIKELY(shared && !type.is_shared())) {
CHECK(enabled_features_.has_shared());
errorf(pos, "Shared global %i must have shared type, actual type %s",
i + imported_globals, type.name().c_str());
return;
}
// Validation that {type} and {shared} are compatible will happen in
// {consume_init_expr}.
bool ends_with_struct_new = false;
ConstantExpression init =
consume_init_expr(module_.get(), type, &ends_with_struct_new);
module_->globals.push_back(WasmGlobal{
.type = type,
.mutability = mutability,
.init = init,
.index_in_buffer = 0, // set later in CalculateGlobalOffsets
.shared = shared,
.initializer_ends_with_struct_new = ends_with_struct_new});
if (shared) module_->has_shared_part = true;
}
}
void DecodeExportSection() {
uint32_t export_table_count =
consume_count("exports count", kV8MaxWasmExports);
module_->export_table.reserve(export_table_count);
for (uint32_t i = 0; ok() && i < export_table_count; ++i) {
TRACE("DecodeExportTable[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
if (tracer_) {
tracer_->Description("export #");
tracer_->Description(i);
tracer_->NextLine();
}
WireBytesRef name = consume_utf8_string(this, "field name", tracer_);
const uint8_t* kind_pos = pc();
ImportExportKindCode kind =
static_cast<ImportExportKindCode>(consume_u8("kind", tracer_));
module_->export_table.push_back(WasmExport{.name = name, .kind = kind});
WasmExport* exp = &module_->export_table.back();
if (tracer_) {
tracer_->Description(": ");
tracer_->Description(ExternalKindName(exp->kind));
tracer_->Description(" ");
}
switch (kind) {
case kExternalFunction: {
WasmFunction* func = nullptr;
exp->index = consume_func_index(module_.get(), &func);
if (V8_UNLIKELY(failed())) break;
DCHECK_NOT_NULL(func);
module_->num_exported_functions++;
func->exported = true;
// Exported functions are considered "declared".
func->declared = true;
break;
}
case kExternalTable: {
WasmTable* table = nullptr;
exp->index = consume_table_index(module_.get(), &table);
if (table) table->exported = true;
break;
}
case kExternalMemory: {
const uint8_t* index_pos = pc();
exp->index = consume_u32v("memory index", tracer_);
size_t num_memories = module_->memories.size();
if (V8_UNLIKELY(exp->index >= module_->memories.size())) {
errorf(index_pos,
"invalid exported memory index %u (having %zu memor%s)",
exp->index, num_memories, num_memories == 1 ? "y" : "ies");
break;
}
module_->memories[exp->index].exported = true;
break;
}
case kExternalGlobal: {
WasmGlobal* global = nullptr;
exp->index = consume_global_index(module_.get(), &global);
if (global) {
global->exported = true;
}
break;
}
case kExternalTag: {
WasmTag* tag = nullptr;
exp->index = consume_tag_index(module_.get(), &tag);
break;
}
case kExternalExactFunction:
default:
errorf(kind_pos, "invalid export kind 0x%02x", exp->kind);
break;
}
if (tracer_) tracer_->NextLine();
}
// Check for duplicate exports.
if (ok() && module_->export_table.size() > 1) {
std::vector<WasmExport> sorted_exports(module_->export_table);
auto cmp_less = [this](const WasmExport& a, const WasmExport& b) {
// Return true if a < b.
if (a.name.length() != b.name.length()) {
return a.name.length() < b.name.length();
}
const uint8_t* left =
start() + GetBufferRelativeOffset(a.name.offset());
const uint8_t* right =
start() + GetBufferRelativeOffset(b.name.offset());
return memcmp(left, right, a.name.length()) < 0;
};
std::stable_sort(sorted_exports.begin(), sorted_exports.end(), cmp_less);
auto it = sorted_exports.begin();
WasmExport* last = &*it++;
for (auto end = sorted_exports.end(); it != end; last = &*it++) {
DCHECK(!cmp_less(*it, *last)); // Vector must be sorted.
if (V8_UNLIKELY(!cmp_less(*last, *it))) {
const uint8_t* pc =
start() + GetBufferRelativeOffset(it->name.offset());
TruncatedUserString<> name(pc, it->name.length());
errorf(pc, "Duplicate export name '%.*s' for %s %d and %s %d",
name.length(), name.start(), ExternalKindName(last->kind),
last->index, ExternalKindName(it->kind), it->index);
break;
}
}
}
}
void DecodeStartSection() {
if (tracer_) tracer_->StartOffset(pc_offset());
WasmFunction* func;
const uint8_t* pos = pc_;
module_->start_function_index = consume_func_index(module_.get(), &func);
if (tracer_) tracer_->NextLine();
if (V8_UNLIKELY(func && (func->sig->parameter_count() > 0 ||
func->sig->return_count() > 0))) {
error(pos, "invalid start function: non-zero parameter or return count");
}
}
void DecodeElementSection() {
uint32_t segment_count =
consume_count("segment count", wasm::max_table_size());
for (uint32_t i = 0; i < segment_count; ++i) {
if (tracer_) tracer_->ElementOffset(pc_offset());
WasmElemSegment segment = consume_element_segment_header();
if (tracer_) tracer_->NextLineIfNonEmpty();
if (V8_UNLIKELY(failed())) return;
DCHECK_NE(segment.type, kWasmBottom);
for (uint32_t j = 0; j < segment.element_count; j++) {
// Just run validation on elements; do not store them anywhere. We will
// decode them again from wire bytes as needed.
consume_element_segment_entry(module_.get(), segment);
if (V8_UNLIKELY(failed())) return;
}
module_->elem_segments.push_back(std::move(segment));
}
}
void DecodeCodeSection() {
// Make sure global offset were calculated before they get accessed during
// function compilation.
CalculateGlobalOffsets(module_.get());
uint32_t code_section_start = pc_offset();
uint32_t functions_count = consume_u32v("functions count", tracer_);
if (tracer_) {
tracer_->Description(functions_count);
tracer_->NextLine();
}
CheckFunctionsCount(functions_count, code_section_start);
auto inst_traces_it = this->inst_traces_.begin();
std::vector<std::pair<uint32_t, uint32_t>> inst_traces;
for (uint32_t i = 0; ok() && i < functions_count; ++i) {
int function_index = module_->num_imported_functions + i;
if (tracer_) {
tracer_->Description("function #");
tracer_->FunctionName(function_index);
tracer_->NextLine();
}
const uint8_t* pos = pc();
uint32_t size = consume_u32v("body size", tracer_);
if (tracer_) {
tracer_->Description(size);
tracer_->NextLine();
}
if (V8_UNLIKELY(size > kV8MaxWasmFunctionSize)) {
errorf(pos, "size %u > maximum function size %zu", size,
kV8MaxWasmFunctionSize);
return;
}
uint32_t offset = pc_offset();
consume_bytes(size, "function body");
if (V8_UNLIKELY(failed())) break;
DecodeFunctionBody(function_index, size, offset);
// Now that the function has been decoded, we can compute module offsets.
for (; inst_traces_it != this->inst_traces_.end() &&
std::get<0>(*inst_traces_it) == i;
++inst_traces_it) {
uint32_t trace_offset = offset + std::get<1>(*inst_traces_it);
uint32_t mark_id = std::get<2>(*inst_traces_it);
std::pair<uint32_t, uint32_t> trace_mark = {trace_offset, mark_id};
inst_traces.push_back(trace_mark);
}
}
// If we have actually decoded traces and they were all decoded without
// error, then we can move them to the module. If any errors are found, it
// is safe to throw away all traces.
if (V8_UNLIKELY(!inst_traces.empty() &&
inst_traces_it == this->inst_traces_.end())) {
// This adds an invalid entry at the end of the traces. An invalid entry
// is defined as having an module offset of 0 and a markid of 0.
inst_traces.push_back({0, 0});
this->module_->inst_traces = std::move(inst_traces);
}
DCHECK_GE(pc_offset(), code_section_start);
module_->code = {code_section_start, pc_offset() - code_section_start};
}
void StartCodeSection(WireBytesRef section_bytes) {
CheckSectionOrder(kCodeSectionCode);
// Make sure global offset were calculated before they get accessed during
// function compilation.
CalculateGlobalOffsets(module_.get());
module_->code = section_bytes;
}
bool CheckFunctionsCount(uint32_t functions_count, uint32_t error_offset) {
if (V8_UNLIKELY(functions_count != module_->num_declared_functions)) {
errorf(error_offset, "function body count %u mismatch (%u expected)",
functions_count, module_->num_declared_functions);
return false;
}
return true;
}
void DecodeFunctionBody(uint32_t func_index, uint32_t length,
uint32_t offset) {
WasmFunction* function = &module_->functions[func_index];
function->code = {offset, length};
constexpr uint32_t kSmallFunctionThreshold = 50;
if (length < kSmallFunctionThreshold) {
++module_->num_small_functions;
}
if (tracer_) {
tracer_->FunctionBody(function, pc_ - (pc_offset() - offset));
}
}
bool CheckDataSegmentsCount(uint32_t data_segments_count) {
if (V8_UNLIKELY(has_seen_unordered_section(kDataCountSectionCode) &&
data_segments_count !=
module_->num_declared_data_segments)) {
errorf(pc(), "data segments count %u mismatch (%u expected)",
data_segments_count, module_->num_declared_data_segments);
return false;
}
return true;
}
struct DataSegmentHeader {
bool is_active;
SharedFlag is_shared;
uint32_t memory_index;
ConstantExpression dest_addr;
};
void DecodeDataSection() {
uint32_t data_segments_count =
consume_count("data segments count", kV8MaxWasmDataSegments);
if (!CheckDataSegmentsCount(data_segments_count)) return;
module_->data_segments.reserve(data_segments_count);
for (uint32_t i = 0; i < data_segments_count; ++i) {
TRACE("DecodeDataSegment[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
if (tracer_) tracer_->DataOffset(pc_offset());
DataSegmentHeader header = consume_data_segment_header();
uint32_t source_length = consume_u32v("source size", tracer_);
if (tracer_) {
tracer_->Description(source_length);
tracer_->NextLine();
}
uint32_t source_offset = pc_offset();
if (tracer_) {
tracer_->Bytes(pc_, source_length);
tracer_->Description("segment data");
tracer_->NextLine();
}
consume_bytes(source_length, "segment data");
if (V8_UNLIKELY(failed())) break;
module_->data_segments.emplace_back(
header.is_active, header.is_shared, header.memory_index,
header.dest_addr, WireBytesRef{source_offset, source_length});
}
}
void DecodeNameSection() {
if (tracer_) {
tracer_->NameSection(
pc_, end_, buffer_offset_ + static_cast<uint32_t>(pc_ - start_));
}
// TODO(titzer): find a way to report name errors as warnings.
// Ignore all but the first occurrence of name section.
if (!has_seen_unordered_section(kNameSectionCode)) {
set_seen_unordered_section(kNameSectionCode);
module_->name_section = {buffer_offset_,
static_cast<uint32_t>(end_ - start_)};
// Use an inner decoder so that errors don't fail the outer decoder.
Decoder inner(start_, pc_, end_, buffer_offset_);
// Decode all name subsections.
// Be lenient with their order.
while (inner.ok() && inner.more()) {
uint8_t name_type = inner.consume_u8("name type");
if (name_type & 0x80) inner.error("name type if not varuint7");
uint32_t name_payload_len = inner.consume_u32v("name payload length");
if (!inner.checkAvailable(name_payload_len)) break;
// Decode module name, ignore the rest.
// Function and local names will be decoded when needed.
if (name_type == NameSectionKindCode::kModuleCode) {
WireBytesRef name =
consume_string(&inner, unibrow::Utf8Variant::kLossyUtf8,
"module name", ITracer::NoTrace);
if (inner.ok() && validate_utf8(&inner, name)) {
module_->name = name;
}
} else {
inner.consume_bytes(name_payload_len, "name subsection payload");
}
}
}
// Skip the whole names section in the outer decoder.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeSourceMappingURLSection() {
Decoder inner(start_, pc_, end_, buffer_offset_);
WireBytesRef url =
wasm::consume_utf8_string(&inner, "module name", tracer_);
if (inner.ok() &&
module_->debug_symbols[WasmDebugSymbols::Type::SourceMap].type ==
WasmDebugSymbols::None) {
module_->debug_symbols[WasmDebugSymbols::Type::SourceMap] = {
WasmDebugSymbols::Type::SourceMap, url};
}
set_seen_unordered_section(kSourceMappingURLSectionCode);
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeExternalDebugInfoSection() {
Decoder inner(start_, pc_, end_, buffer_offset_);
WireBytesRef url =
wasm::consume_utf8_string(&inner, "external symbol file", tracer_);
if (inner.ok()) {
module_->debug_symbols[WasmDebugSymbols::Type::ExternalDWARF] = {
WasmDebugSymbols::Type::ExternalDWARF, url};
set_seen_unordered_section(kExternalDebugInfoSectionCode);
}
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeBuildIdSection() {
Decoder inner(start_, pc_, end_, buffer_offset_);
WireBytesRef build_id =
consume_string(&inner, unibrow::Utf8Variant::kLossyUtf8, "build_id");
if (inner.ok()) {
module_->build_id = build_id;
set_seen_unordered_section(kBuildIdSectionCode);
}
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeInstTraceSection() {
TRACE("DecodeInstTrace module+%d\n", static_cast<int>(pc_ - start_));
if (!has_seen_unordered_section(kInstTraceSectionCode)) {
set_seen_unordered_section(kInstTraceSectionCode);
// Use an inner decoder so that errors don't fail the outer decoder.
Decoder inner(start_, pc_, end_, buffer_offset_);
std::vector<std::tuple<uint32_t, uint32_t, uint32_t>> inst_traces;
uint32_t func_count = inner.consume_u32v("number of functions");
// Keep track of the previous function index to validate the ordering.
int64_t last_func_idx = -1;
for (uint32_t i = 0; i < func_count; i++) {
uint32_t func_idx = inner.consume_u32v("function index");
if (V8_UNLIKELY(int64_t{func_idx} <= last_func_idx)) {
inner.errorf("Invalid function index: %d", func_idx);
break;
}
last_func_idx = func_idx;
uint32_t num_traces = inner.consume_u32v("number of trace marks");
TRACE("DecodeInstTrace[%d] module+%d\n", func_idx,
static_cast<int>(inner.pc() - inner.start()));
// Keep track of the previous offset to validate the ordering.
int64_t last_func_off = -1;
for (uint32_t j = 0; j < num_traces; ++j) {
uint32_t func_off = inner.consume_u32v("function offset");
uint32_t mark_size = inner.consume_u32v("mark size");
uint32_t trace_mark_id = 0;
// Build the mark id from the individual bytes.
for (uint32_t k = 0; k < mark_size; k++) {
trace_mark_id |= inner.consume_u8("trace mark id") << k * 8;
}
if (V8_UNLIKELY(int64_t{func_off} <= last_func_off)) {
inner.errorf("Invalid branch offset: %d", func_off);
break;
}
last_func_off = func_off;
TRACE("DecodeInstTrace[%d][%d] module+%d\n", func_idx, func_off,
static_cast<int>(inner.pc() - inner.start()));
// Store the function index, function offset, and mark id into a
// temporary 3-tuple. This will later be translated to a module
// offset and mark id.
std::tuple<uint32_t, uint32_t, uint32_t> mark_tuple = {
func_idx, func_off, trace_mark_id};
inst_traces.push_back(mark_tuple);
}
}
// Extra unexpected bytes are an error.
if (V8_UNLIKELY(inner.more())) {
inner.errorf("Unexpected extra bytes: %d\n",
static_cast<int>(inner.pc() - inner.start()));
}
// If everything went well, accept the traces for the module.
if (inner.ok()) {
this->inst_traces_ = std::move(inst_traces);
}
}
// Skip the whole instruction trace section in the outer decoder.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeBranchHintsSection() {
TRACE("DecodeBranchHints module+%d\n", static_cast<int>(pc_ - start_));
detected_features_->add_branch_hinting();
if (!has_seen_unordered_section(kBranchHintsSectionCode)) {
set_seen_unordered_section(kBranchHintsSectionCode);
// Use an inner decoder so that errors don't fail the outer decoder.
Decoder inner(start_, pc_, end_, buffer_offset_);
BranchHintInfo branch_hints;
uint32_t func_count = inner.consume_u32v("number of functions");
// Keep track of the previous function index to validate the ordering
int64_t last_func_idx = -1;
for (uint32_t i = 0; i < func_count; i++) {
uint32_t func_idx = inner.consume_u32v("function index");
if (V8_UNLIKELY(int64_t{func_idx} <= last_func_idx)) {
inner.errorf("Invalid function index: %d", func_idx);
break;
}
last_func_idx = func_idx;
uint32_t num_hints = inner.consume_u32v("number of hints");
BranchHintMap func_branch_hints;
TRACE("DecodeBranchHints[%d] module+%d\n", func_idx,
static_cast<int>(inner.pc() - inner.start()));
// Keep track of the previous branch offset to validate the ordering
int64_t last_br_off = -1;
for (uint32_t j = 0; j < num_hints; ++j) {
uint32_t br_off = inner.consume_u32v("branch instruction offset");
if (V8_UNLIKELY(int64_t{br_off} <= last_br_off)) {
inner.errorf("Invalid branch offset: %d", br_off);
break;
}
last_br_off = br_off;
uint32_t data_size = inner.consume_u32v("data size");
if (V8_UNLIKELY(data_size != 1)) {
inner.errorf("Invalid data size: %#x. Expected 1.", data_size);
break;
}
uint32_t br_dir = inner.consume_u8("branch direction");
TRACE("DecodeBranchHints[%d][%d] module+%d\n", func_idx, br_off,
static_cast<int>(inner.pc() - inner.start()));
BranchHint hint;
switch (br_dir) {
case 0:
hint = BranchHint::kFalse;
break;
case 1:
hint = BranchHint::kTrue;
break;
default:
hint = BranchHint::kNone;
inner.errorf(inner.pc(), "Invalid branch hint %#x", br_dir);
break;
}
if (V8_UNLIKELY(!inner.ok())) {
break;
}
func_branch_hints.insert(br_off, hint);
}
if (V8_UNLIKELY(!inner.ok())) {
break;
}
branch_hints.emplace(func_idx, std::move(func_branch_hints));
}
// Extra unexpected bytes are an error.
if (V8_UNLIKELY(inner.more())) {
inner.errorf("Unexpected extra bytes: %d\n",
static_cast<int>(inner.pc() - inner.start()));
}
// If everything went well, accept the hints for the module.
if (inner.ok()) {
module_->branch_hints = std::move(branch_hints);
} else {
TRACE("DecodeBranchHints error: %s", inner.error().message().c_str());
}
}
// Skip the whole branch hints section in the outer decoder.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeCompilationPrioritySection() {
TRACE("DecodeCompilationPriority module+%d\n",
static_cast<int>(pc_ - start_));
detected_features_->add_compilation_hints();
if (!has_seen_unordered_section(kCompilationPrioritySectionCode)) {
set_seen_unordered_section(kCompilationPrioritySectionCode);
// Use an inner decoder so that errors don't fail the outer decoder.
Decoder inner(start_, pc_, end_, buffer_offset_);
CompilationPriorities compilation_priorities;
uint32_t func_count = inner.consume_u32v("number of functions");
int64_t last_func_index = -1;
for (uint32_t i = 0; i < func_count; i++) {
uint32_t func_index = inner.consume_u32v("function index");
if (V8_UNLIKELY(static_cast<int64_t>(func_index) <= last_func_index)) {
inner.error("out of order functions");
break;
}
last_func_index = func_index;
uint32_t byte_offset = inner.consume_u32v("byte offset");
if (V8_UNLIKELY(byte_offset != 0)) {
inner.error("byte offset has to be 0 (function level only)");
break;
}
uint32_t hint_length = inner.consume_u32v("hint length");
const uint8_t* pc_after_hint_length = inner.pc();
uint32_t compilation_priority =
inner.consume_u32v("compilation priority");
if (V8_UNLIKELY(static_cast<int64_t>(hint_length) <
inner.pc() - pc_after_hint_length)) {
inner.error("Compilation priority longer than declared hint length");
break;
}
int optimization_priority = kOptimizationPriorityNotSpecifiedSentinel;
// If we exhausted the declared hint length, do not parse optimization
// priority.
if (static_cast<int64_t>(hint_length) >
inner.pc() - pc_after_hint_length) {
uint32_t parsed_priority =
inner.consume_u32v("optimization priority");
if (V8_UNLIKELY(static_cast<int>(parsed_priority) >
kOptimizationPriorityExecutedOnceSentinel)) {
inner.error("Optimization priority too large");
break;
}
optimization_priority = static_cast<int>(parsed_priority);
if (V8_UNLIKELY(static_cast<int64_t>(hint_length) <
inner.pc() - pc_after_hint_length)) {
inner.error("Optimization priority overflows declared hint length");
break;
}
}
// Ignore remaining hint bytes.
inner.consume_bytes(
hint_length -
static_cast<uint32_t>(inner.pc() - pc_after_hint_length));
if (!inner.ok()) break;
compilation_priorities.emplace(
func_index,
CompilationPriority{compilation_priority, optimization_priority});
}
// Extra unexpected bytes are an error.
if (V8_UNLIKELY(inner.more())) {
inner.errorf("Unexpected extra bytes: %d\n",
static_cast<int>(inner.pc() - inner.start()));
}
// If everything went well, accept the compilation priority hints for the
// module.
if (inner.ok()) {
module_->compilation_priorities = std::move(compilation_priorities);
} else if (v8_flags.trace_wasm_decoder ||
v8_flags.trace_wasm_compilation_hints) {
PrintF("DecodeCompilationPriority error, offset %d: %s\n",
inner.error().offset(), inner.error().message().c_str());
}
}
// Skip the whole compilation priority section in the outer decoder.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeInstructionFrequenciesSection() {
TRACE("DecodeInstructionFrequencies module+%d\n",
static_cast<int>(pc_ - start_));
detected_features_->add_compilation_hints();
if (!has_seen_unordered_section(kInstFrequenciesSectionCode)) {
set_seen_unordered_section(kInstFrequenciesSectionCode);
// Use an inner decoder so that errors don't fail the outer decoder.
Decoder inner(start_, pc_, end_, buffer_offset_);
InstructionFrequencies frequencies;
uint32_t func_count = inner.consume_u32v("number of functions");
int64_t last_func_index = -1;
for (uint32_t i = 0; i < func_count; i++) {
uint32_t func_index = inner.consume_u32v("function index");
if (V8_UNLIKELY(static_cast<int64_t>(func_index) <= last_func_index)) {
inner.error("out of order functions");
break;
}
last_func_index = func_index;
int64_t last_byte_offset = -1;
uint32_t hints_count = inner.consume_u32v("hints count");
for (uint32_t hint = 0; hint < hints_count; hint++) {
uint32_t byte_offset = inner.consume_u32v("byte offset");
if (V8_UNLIKELY(static_cast<int64_t>(byte_offset) <=
last_byte_offset)) {
inner.error("out of order hints");
break;
}
last_byte_offset = byte_offset;
uint32_t hint_length = inner.consume_u32v("hint length");
if (V8_UNLIKELY(hint_length == 0)) {
inner.error("hint length must be larger than 0");
break;
}
uint8_t frequency = inner.consume_u8("frequency");
if (V8_UNLIKELY(!(frequency <= 64 || frequency == 127))) {
inner.error("invalid frequency");
break;
}
// Skip remaining hint bytes.
if (hint_length > 1) {
inner.consume_bytes(hint_length - 1);
}
frequencies[func_index].emplace_back(byte_offset, frequency);
}
}
// Extra unexpected bytes are an error.
if (V8_UNLIKELY(inner.more())) {
inner.errorf("Unexpected extra bytes: %d\n",
static_cast<int>(inner.pc() - inner.start()));
}
// If everything went well, accept the instruction-frequency hints for the
// module.
if (inner.ok()) {
module_->instruction_frequencies = std::move(frequencies);
} else if (v8_flags.trace_wasm_decoder ||
v8_flags.trace_wasm_compilation_hints) {
PrintF("DecodeInstructionFrequencies error, offset %d: %s\n",
inner.error().offset(), inner.error().message().c_str());
}
}
// Skip the whole instruction frequencies section in the outer decoder.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeCallTargetsSection() {
TRACE("DecodeCallTargets module+%d\n", static_cast<int>(pc_ - start_));
detected_features_->add_compilation_hints();
if (!has_seen_unordered_section(kCallTargetsSectionCode)) {
set_seen_unordered_section(kCallTargetsSectionCode);
// Use an inner decoder so that errors don't fail the outer decoder.
Decoder inner(start_, pc_, end_, buffer_offset_);
CallTargets call_targets;
uint32_t func_count = inner.consume_u32v("number of functions");
int64_t last_func_index = -1;
for (uint32_t i = 0; i < func_count; i++) {
uint32_t func_index = inner.consume_u32v("function index");
if (V8_UNLIKELY(static_cast<int64_t>(func_index) <= last_func_index)) {
inner.error("out of order functions");
break;
}
last_func_index = func_index;
int64_t last_byte_offset = -1;
uint32_t hints_count = inner.consume_u32v("hints count");
for (uint32_t hint = 0; hint < hints_count; hint++) {
uint32_t byte_offset = inner.consume_u32v("byte offset");
if (V8_UNLIKELY(static_cast<int64_t>(byte_offset) <=
last_byte_offset)) {
inner.error("out of order hints");
break;
}
last_byte_offset = byte_offset;
uint32_t hint_length = inner.consume_u32v("hint length");
if (V8_UNLIKELY(hint_length == 0)) {
inner.error("hint length must be greater than 0");
break;
}
CallTargetVector call_targets_for_offset;
while (hint_length > 0) {
auto [function_index, function_index_length] =
inner.read_u32v<FullValidationTag>(inner.pc(),
"function index");
if (V8_UNLIKELY(inner.failed())) break;
if (V8_UNLIKELY(function_index_length > hint_length)) {
inner.error("function length overflows declared hint length");
break;
}
hint_length -= function_index_length;
inner.consume_bytes(function_index_length);
auto [call_frequency, call_frequency_length] =
inner.read_u32v<FullValidationTag>(inner.pc(),
"call frequency");
if (V8_UNLIKELY(inner.failed())) break;
if (V8_UNLIKELY(call_frequency_length > hint_length)) {
inner.error("call frequency overflows declared hint length");
break;
}
if (V8_UNLIKELY(call_frequency > 100U)) {
inner.error("invalid call frequency percentage");
break;
}
hint_length -= call_frequency_length;
inner.consume_bytes(call_frequency_length);
call_targets_for_offset.emplace_back(function_index,
call_frequency);
}
if (V8_UNLIKELY(inner.failed())) break;
DCHECK_EQ(hint_length, 0);
uint32_t sum_of_percentages = 0;
for (CallTarget& call_target : call_targets_for_offset) {
sum_of_percentages += call_target.call_frequency_percent;
}
if (V8_UNLIKELY(sum_of_percentages > 100U)) {
inner.error("percentages must sum to at most 100");
break;
}
call_targets[func_index].emplace_back(byte_offset,
call_targets_for_offset);
}
if (V8_UNLIKELY(inner.failed())) break;
}
// Extra unexpected bytes are an error.
if (V8_UNLIKELY(inner.more())) {
inner.errorf("Unexpected extra bytes: %d\n",
static_cast<int>(inner.pc() - inner.start()));
}
// If everything went well, accept the call-target hints for the module.
if (inner.ok()) {
module_->call_targets = std::move(call_targets);
} else if (v8_flags.trace_wasm_decoder ||
v8_flags.trace_wasm_compilation_hints) {
PrintF("DecodeCallTargets error, offset %d: %s\n",
inner.error().offset(), inner.error().message().c_str());
}
}
// Skip the whole call-targets section in the outer decoder.
consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeDataCountSection() {
module_->num_declared_data_segments =
consume_count("data segments count", kV8MaxWasmDataSegments);
if (tracer_) tracer_->NextLineIfNonEmpty();
}
void DecodeTagSection() {
uint32_t tag_count = consume_count("tag count", kV8MaxWasmTags);
for (uint32_t i = 0; ok() && i < tag_count; ++i) {
TRACE("DecodeTag[%d] module+%d\n", i, static_cast<int>(pc_ - start_));
if (tracer_) tracer_->TagOffset(pc_offset());
const WasmTagSig* tag_sig = nullptr;
consume_exception_attribute(); // Attribute ignored for now.
ModuleTypeIndex sig_index =
consume_tag_sig_index(module_.get(), &tag_sig);
module_->tags.emplace_back(tag_sig, sig_index);
}
}
void DecodeStringRefSection() {
uint32_t deferred = consume_count("deferred string literal count",
kV8MaxWasmStringLiterals);
if (V8_UNLIKELY(deferred)) {
errorf(pc(), "Invalid deferred string literal count %u (expected 0)",
deferred);
}
uint32_t immediate = consume_count("string literal count",
kV8MaxWasmStringLiterals - deferred);
for (uint32_t i = 0; ok() && i < immediate; ++i) {
TRACE("DecodeStringLiteral[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
if (tracer_) tracer_->StringOffset(pc_offset());
// TODO(12868): Throw if the string's utf-16 length > String::kMaxLength.
WireBytesRef pos = wasm::consume_string(this, unibrow::Utf8Variant::kWtf8,
"string literal", tracer_);
module_->stringref_literals.emplace_back(pos);
}
}
bool CheckMismatchedCounts() {
// The declared vs. defined function count is normally checked when
// decoding the code section, but we have to check it here too in case the
// code section is absent.
if (module_->num_declared_functions != 0) {
DCHECK_LT(module_->num_imported_functions, module_->functions.size());
// We know that the code section has been decoded if the first
// non-imported function has its code set.
if (V8_UNLIKELY(!module_->functions[module_->num_imported_functions]
.code.is_set())) {
errorf(pc(), "function count is %u, but code section is absent",
module_->num_declared_functions);
return false;
}
}
// Perform a similar check for the DataCount and Data sections, where data
// segments are declared but the Data section is absent.
if (V8_UNLIKELY(!CheckDataSegmentsCount(
static_cast<uint32_t>(module_->data_segments.size())))) {
return false;
}
return true;
}
ModuleResult FinishDecoding() {
if (ok() && CheckMismatchedCounts()) {
// We calculate the global offsets here, because there may not be a
// global section and code section that would have triggered the
// calculation before. Even without the globals section the calculation
// is needed because globals can also be defined in the import section.
CalculateGlobalOffsets(module_.get());
}
if (module_->has_shared_part) detected_features_->add_shared();
return toResult(std::move(module_));
}
// Decodes an entire module.
ModuleResult DecodeModule(bool validate_functions) {
// Keep a reference to the wire bytes, in case this decoder gets reset on
// error.
base::Vector<const uint8_t> wire_bytes(start_, end_ - start_);
size_t max_size = max_module_size();
if (V8_UNLIKELY(wire_bytes.size() > max_size)) {
return ModuleResult{WasmError{0, "size > maximum module size (%zu): %zu",
max_size, wire_bytes.size()}};
}
DecodeModuleHeader(wire_bytes);
if (V8_UNLIKELY(failed())) return toResult(nullptr);
static constexpr uint32_t kWasmHeaderSize = 8;
Decoder section_iterator_decoder(start_ + kWasmHeaderSize, end_,
kWasmHeaderSize);
WasmSectionIterator section_iter(§ion_iterator_decoder, tracer_);
while (ok()) {
if (section_iter.section_code() != SectionCode::kUnknownSectionCode) {
uint32_t offset = static_cast<uint32_t>(section_iter.payload().begin() -
wire_bytes.begin());
DecodeSection(section_iter.section_code(), section_iter.payload(),
offset);
if (V8_UNLIKELY(!ok())) break;
}
if (!section_iter.more()) break;
section_iter.advance(true);
}
// Check for module structure errors before validating function bodies, to
// produce consistent error message independent of whether validation
// happens here or later.
if (V8_UNLIKELY(section_iterator_decoder.failed())) {
return section_iterator_decoder.toResult(nullptr);
}
ModuleResult result = FinishDecoding();
if (!result.failed() && validate_functions) {
if (WasmError validation_error =
ValidateFunctions(module_.get(), enabled_features_, wire_bytes,
detected_features_)) {
result = ModuleResult{validation_error};
}
}
if (v8_flags.dump_wasm_module) DumpModule(wire_bytes, result.ok());
return result;
}
// Decodes a single function signature at {start}.
const FunctionSig* DecodeFunctionSignatureForTesting(const uint8_t* start) {
pc_ = start;
if (V8_UNLIKELY(!expect_u8("type form", kWasmFunctionTypeCode))) {
return nullptr;
}
const FunctionSig* result = consume_sig();
return ok() ? result : nullptr;
}
// Takes a module as parameter so that wasm-disassembler.cc can pass its own
// module.
ConstantExpression consume_element_segment_entry(
WasmModule* module, const WasmElemSegment& segment) {
if (segment.element_type == WasmElemSegment::kExpressionElements) {
return consume_init_expr(module, segment.type);
} else {
return ConstantExpression::RefFunc(
consume_element_func_index(module, segment.type));
}
}
const std::shared_ptr<WasmModule>& shared_module() const { return module_; }
private:
bool has_seen_unordered_section(SectionCode section_code) {
return seen_unordered_sections_ & (1 << section_code);
}
void set_seen_unordered_section(SectionCode section_code) {
seen_unordered_sections_ |= 1 << section_code;
}
uint32_t off(const uint8_t* ptr) {
return static_cast<uint32_t>(ptr - start_) + buffer_offset_;
}
// Calculate individual global offsets and total size of globals table. This
// function should be called after all globals have been defined, which is
// after the import section and the global section, but before the global
// offsets are accessed, e.g. by the function compilers. The moment when this
// function should be called is not well-defined, as the global section may
// not exist. Therefore this function is called multiple times.
void CalculateGlobalOffsets(WasmModule* module) {
if (module->globals.empty() || module->untagged_globals_buffer_size != 0 ||
module->tagged_globals_buffer_size != 0) {
// This function has already been executed before, so we don't have to
// execute it again.
return;
}
uint32_t untagged_index = 0;
uint32_t tagged_index = 0;
uint32_t num_imported_mutable_globals = 0;
for (WasmGlobal& global : module->globals) {
if (global.mutability && global.imported) {
global.mutable_imported_global_index = num_imported_mutable_globals++;
} else if (global.type.is_ref()) {
global.index_in_buffer = tagged_index;
// All entries in the tagged_globals_buffer have size 1.
tagged_index++;
} else {
int size = global.type.value_kind_size();
untagged_index = (untagged_index + size - 1) & ~(size - 1); // align
global.index_in_buffer = untagged_index;
untagged_index += size;
}
}
module->untagged_globals_buffer_size = untagged_index;
module->tagged_globals_buffer_size = tagged_index;
}
ModuleTypeIndex consume_sig_index(WasmModule* module,
const FunctionSig** sig) {
const uint8_t* pos = pc_;
ModuleTypeIndex sig_index{consume_u32v("signature index")};
if (tracer_) tracer_->Bytes(pos, static_cast<uint32_t>(pc_ - pos));
if (V8_UNLIKELY(!module->has_signature(sig_index))) {
errorf(pos, "no signature at index %u (%d types)", sig_index.index,
static_cast<int>(module->types.size()));
*sig = nullptr;
return {};
}
*sig = module->signature(sig_index);
if (tracer_) {
tracer_->Description(*sig);
tracer_->NextLine();
}
return sig_index;
}
ModuleTypeIndex consume_tag_sig_index(WasmModule* module,
const FunctionSig** sig) {
const uint8_t* pos = pc_;
ModuleTypeIndex sig_index = consume_sig_index(module, sig);
if (V8_UNLIKELY(!enabled_features_.has_wasmfx() && *sig &&
(*sig)->return_count() != 0)) {
errorf(pos, "tag signature %u has non-void return", sig_index);
*sig = nullptr;
return {};
}
return sig_index;
}
uint32_t consume_count(const char* name, size_t maximum) {
const uint8_t* p = pc_;
uint32_t count = consume_u32v(name, tracer_);
if (tracer_) {
tracer_->Description(count);
if (count == 1) {
tracer_->Description(": ");
} else {
tracer_->NextLine();
}
}
if (V8_UNLIKELY(count > maximum)) {
errorf(p, "%s of %u exceeds internal limit of %zu", name, count, maximum);
return 0;
}
return count;
}
uint32_t consume_func_index(WasmModule* module, WasmFunction** func) {
return consume_index("function", &module->functions, func);
}
uint32_t consume_global_index(WasmModule* module, WasmGlobal** global) {
return consume_index("global", &module->globals, global);
}
uint32_t consume_table_index(WasmModule* module, WasmTable** table) {
return consume_index("table", &module->tables, table);
}
uint32_t consume_tag_index(WasmModule* module, WasmTag** tag) {
return consume_index("tag", &module->tags, tag);
}
template <typename T>
uint32_t consume_index(const char* name, std::vector<T>* vector, T** ptr) {
const uint8_t* pos = pc_;
uint32_t index = consume_u32v("index", tracer_);
if (tracer_) {
tracer_->Description(": ");
tracer_->Description(index);
}
if (V8_UNLIKELY(index >= vector->size())) {
errorf(pos, "%s index %u out of bounds (%d entr%s)", name, index,
static_cast<int>(vector->size()),
vector->size() == 1 ? "y" : "ies");
*ptr = nullptr;
return 0;
}
*ptr = &(*vector)[index];
return index;
}
// The limits byte structure is used for memories and tables.
struct LimitsByte {
uint8_t flags;
// Flags 0..7 are valid (3 bits).
bool is_valid() const { return (flags & ~0x7) == 0; }
bool has_maximum() const { return flags & 0x1; }
SharedFlag is_shared() const {
return (flags & 0x2) ? SharedFlag{true} : SharedFlag{false};
}
bool is_64bit() const { return flags & 0x4; }
AddressType address_type() const {
return is_64bit() ? AddressType::kI64 : AddressType::kI32;
}
};
enum LimitsByteType { kMemory, kTable };
template <LimitsByteType limits_type>
LimitsByte consume_limits_byte() {
if (tracer_) tracer_->Bytes(pc_, 1);
LimitsByte limits{consume_u8(
limits_type == kMemory ? "memory limits flags" : "table limits flags")};
if (V8_UNLIKELY(!limits.is_valid())) {
errorf(pc() - 1, "invalid %s limits flags 0x%x",
limits_type == kMemory ? "memory" : "table", limits.flags);
}
if (limits.is_shared()) {
if constexpr (limits_type == kMemory) {
// V8 does not support shared memory without a maximum.
if (V8_UNLIKELY(!limits.has_maximum())) {
error(pc() - 1, "shared memory must have a maximum defined");
}
// TODO(42204563): Implement proper handling of shared memories when
// Shared Everything is enabled.
} else if (V8_UNLIKELY(!enabled_features_.has_shared())) { // table
error(pc() - 1, "invalid table limits flags");
} else {
// TODO(42204563): Support shared tables.
error(pc() - 1, "shared tables are not supported yet");
}
}
if (tracer_) {
if (limits.is_shared()) {
tracer_->Description(" shared");
}
if (limits.is_64bit()) {
tracer_->Description(limits_type == kMemory ? " mem64" : " table64");
}
tracer_->Description(limits.has_maximum() ? " with maximum"
: " no maximum");
tracer_->NextLine();
}
return limits;
}
void consume_table_flags(WasmTable* table) {
LimitsByte limits = consume_limits_byte<kTable>();
table->has_maximum_size = limits.has_maximum();
table->shared = limits.is_shared();
table->address_type = limits.address_type();
if (table->is_table64()) detected_features_->add_memory64();
}
void consume_memory_flags(WasmMemory* memory) {
LimitsByte limits = consume_limits_byte<kMemory>();
memory->has_maximum_pages = limits.has_maximum();
memory->is_shared = limits.is_shared();
memory->address_type = limits.address_type();
if (memory->is_shared) {
detected_features_->add_shared_memory();
}
if (memory->is_memory64()) detected_features_->add_memory64();
}
std::pair<bool, SharedFlag> consume_global_flags() {
uint8_t flags = consume_u8("global flags");
if (V8_UNLIKELY(flags & ~0b11)) {
errorf(pc() - 1, "invalid global flags 0x%x", flags);
return {false, SharedFlag{false}};
}
bool mutability = flags & 0b1;
bool shared = flags & 0b10;
if (tracer_) {
tracer_->Bytes(pc_ - 1, 1); // The flags byte.
if (shared) tracer_->Description(" shared");
tracer_->Description(mutability ? " mutable" : " immutable");
}
if (V8_UNLIKELY(shared && !enabled_features_.has_shared())) {
errorf(pc() - 1, "invalid global flags 0x%x", flags);
return {false, SharedFlag{false}};
}
if (shared) {
// TODO(42204563): Support shared globals.
error(pc() - 1, "shared globals are not supported yet");
return {false, SharedFlag{false}};
}
return {mutability, SharedFlag(shared)};
}
enum ResizableLimitsType : bool { k32BitLimits, k64BitLimits };
void consume_resizable_limits(
const char* name, const char* units,
// Not: both memories and tables have a 32-bit limit on the initial size.
uint32_t max_initial, uint32_t* initial, bool has_maximum,
uint64_t max_maximum, uint64_t* maximum, ResizableLimitsType type) {
const uint8_t* pos = pc();
// Note that even if we read the values as 64-bit value, all V8 limits are
// still within uint32_t range.
uint64_t initial_64 = type == k64BitLimits
? consume_u64v("initial size", tracer_)
: consume_u32v("initial size", tracer_);
if (V8_UNLIKELY(initial_64 > max_initial)) {
errorf(pos,
"initial %s size (%" PRIu64
" %s) is larger than implementation limit (%u %s)",
name, initial_64, units, max_initial, units);
}
*initial = static_cast<uint32_t>(initial_64);
if (tracer_) {
tracer_->Description(*initial);
tracer_->NextLine();
}
if (has_maximum) {
pos = pc();
uint64_t maximum_64 = type == k64BitLimits
? consume_u64v("maximum size", tracer_)
: consume_u32v("maximum size", tracer_);
if (V8_UNLIKELY(maximum_64 > max_maximum)) {
errorf(pos,
"maximum %s size (%" PRIu64
" %s) is larger than implementation limit (%" PRIu64 " %s)",
name, maximum_64, units, max_maximum, units);
}
if (V8_UNLIKELY(maximum_64 < *initial)) {
errorf(pos,
"maximum %s size (%" PRIu64 " %s) is less than initial (%u %s)",
name, maximum_64, units, *initial, units);
}
*maximum = maximum_64;
if (tracer_) {
tracer_->Description(*maximum);
tracer_->NextLine();
}
} else {
*maximum = max_initial;
}
}
// Consumes a byte, and emits an error if it does not equal {expected}.
bool expect_u8(const char* name, uint8_t expected) {
const uint8_t* pos = pc();
uint8_t value = consume_u8(name);
if (V8_UNLIKELY(value != expected)) {
errorf(pos, "expected %s 0x%02x, got 0x%02x", name, expected, value);
return false;
}
return true;
}
ConstantExpression consume_init_expr(WasmModule* module, ValueType expected,
bool* ends_with_struct_new = nullptr) {
// The error message mimics the one generated by the {WasmFullDecoder}.
#define TYPE_CHECK(found) \
if (V8_UNLIKELY(!IsSubtypeOf(found, expected, module))) { \
errorf(pc() + 1, \
"type error in constant expression[0] (expected %s, got %s)", \
expected.name().c_str(), found.name().c_str()); \
return {}; \
}
if (tracer_) tracer_->NextLineIfNonEmpty();
// To avoid initializing a {WasmFullDecoder} for the most common
// expressions, we replicate their decoding and validation here. The
// manually handled cases correspond to {ConstantExpression}'s kinds.
// We need to make sure to check that the expression ends in {kExprEnd};
// otherwise, it is just the first operand of a composite expression, and we
// fall back to the default case.
if (V8_UNLIKELY(!more())) {
error("Beyond end of code");
return {};
}
switch (static_cast<WasmOpcode>(*pc())) {
case kExprI32Const: {
auto [value, length] =
read_i32v<FullValidationTag>(pc() + 1, "i32.const");
if (V8_UNLIKELY(failed())) return {};
if (V8_LIKELY(lookahead(1 + length, kExprEnd))) {
TYPE_CHECK(kWasmI32)
if (tracer_) {
tracer_->InitializerExpression(pc_, pc_ + length + 2, kWasmI32);
}
consume_bytes(length + 2);
return ConstantExpression::I32Const(value);
}
break;
}
case kExprRefFunc: {
auto [index, length] =
read_u32v<FullValidationTag>(pc() + 1, "ref.func");
if (V8_UNLIKELY(failed())) return {};
if (V8_LIKELY(lookahead(1 + length, kExprEnd))) {
if (V8_UNLIKELY(index >= module->functions.size())) {
errorf(pc() + 1, "function index %u out of bounds", index);
return {};
}
ModuleTypeIndex functype{module->functions[index].sig_index};
SharedFlag functype_is_shared = module->type(functype).is_shared;
ValueType type = ValueType::Ref(functype, functype_is_shared,
RefTypeKind::kFunction);
if (enabled_features_.has_custom_descriptors() &&
(index >= module->num_imported_functions ||
module->functions[index].exact)) {
type = type.AsExact();
}
TYPE_CHECK(type)
module->functions[index].declared = true;
if (tracer_) {
tracer_->InitializerExpression(pc_, pc_ + length + 2, type);
}
consume_bytes(length + 2);
return ConstantExpression::RefFunc(index);
}
break;
}
case kExprRefNull: {
auto [type, length] =
value_type_reader::read_heap_type<FullValidationTag>(
this, pc() + 1, enabled_features_, detected_features_);
value_type_reader::ValidateHeapType<FullValidationTag>(this, pc_,
module, type);
if (V8_UNLIKELY(failed())) return {};
value_type_reader::Populate(&type, module);
if (V8_LIKELY(lookahead(1 + length, kExprEnd))) {
TYPE_CHECK(ValueType::RefNull(type))
if (tracer_) {
tracer_->InitializerExpression(pc_, pc_ + length + 2,
ValueType::RefNull(type));
}
consume_bytes(length + 2);
return ConstantExpression::RefNull(type);
}
break;
}
default:
break;
}
#undef TYPE_CHECK
auto sig = FixedSizeSignature<ValueType>::Returns(expected);
FunctionBody body(&sig, this->pc_offset(), pc_, end_);
WasmDetectedFeatures detected;
ConstantExpression result;
{
// We need a scope for the decoder because its destructor resets some Zone
// elements, which has to be done before we reset the Zone afterwards.
WasmFullDecoder<Decoder::FullValidationTag, ConstantExpressionInterface,
kConstantExpression>
decoder(&init_expr_zone_, module, enabled_features_, &detected, body,
module);
uint32_t offset = this->pc_offset();
decoder.DecodeFunctionBody();
if (tracer_) {
// In case of error, decoder.end() is set to the position right before
// the byte(s) that caused the error. For debugging purposes, we should
// print these bytes, but we don't know how many of them there are, so
// for now we have to guess. For more accurate behavior, we'd have to
// pass {num_invalid_bytes} to every {decoder->DecodeError()} call.
static constexpr size_t kInvalidBytesGuess = 4;
const uint8_t* end =
decoder.ok() ? decoder.end()
: std::min(decoder.end() + kInvalidBytesGuess, end_);
tracer_->InitializerExpression(pc_, end, expected);
}
this->pc_ = decoder.end();
if (V8_UNLIKELY(decoder.failed())) {
error(decoder.error().offset(), decoder.error().message().c_str());
return {};
}
if (V8_UNLIKELY(!decoder.interface().end_found())) {
error("constant expression is missing 'end'");
return {};
}
result = ConstantExpression::WireBytes(
offset, static_cast<uint32_t>(decoder.end() - decoder.start()));
if (ends_with_struct_new) {
*ends_with_struct_new = decoder.interface().ends_with_struct_new();
}
}
// We reset the zone here; its memory is not used anymore, and we do not
// want memory from all constant expressions to add up.
init_expr_zone_.Reset();
return result;
}
// Read a mutability flag
bool consume_mutability() {
if (tracer_) tracer_->Bytes(pc_, 1);
uint8_t val = consume_u8("mutability");
if (tracer_) {
tracer_->Description(val == 0 ? " immutable"
: val == 1 ? " mutable"
: " invalid");
}
if (V8_UNLIKELY(val > 1)) error(pc_ - 1, "invalid mutability");
return val != 0;
}
// Pass a {module} to get a pre-{Populate()}d ValueType. That's safe
// when the module's type section has already been fully decoded.
ValueType consume_value_type(const WasmModule* module = nullptr) {
auto [result, length] =
value_type_reader::read_value_type<FullValidationTag>(
this, pc_, enabled_features_, detected_features_);
value_type_reader::ValidateValueType<FullValidationTag>(
this, pc_, module_.get(), result);
if (ok() && module) value_type_reader::Populate(&result, module);
if (tracer_) {
tracer_->Bytes(pc_, length);
tracer_->Description(result);
}
consume_bytes(length, "value type");
return result;
}
HeapType consume_heap_type() {
auto [heap_type, length] =
value_type_reader::read_heap_type<FullValidationTag>(
this, pc_, enabled_features_, detected_features_);
value_type_reader::ValidateHeapType<FullValidationTag>(
this, pc_, module_.get(), heap_type);
if (tracer_) {
tracer_->Bytes(pc_, length);
tracer_->Description(heap_type);
}
consume_bytes(length, "heap type");
return heap_type;
}
ValueType consume_storage_type() {
uint8_t opcode = read_u8<FullValidationTag>(this->pc());
switch (opcode) {
case kI8Code:
consume_bytes(1, " i8", tracer_);
return kWasmI8;
case kI16Code:
consume_bytes(1, " i16", tracer_);
return kWasmI16;
default:
// It is not a packed type, so it has to be a value type.
return consume_value_type();
}
}
const FunctionSig* consume_sig() {
if (tracer_) tracer_->NextLine();
// Parse parameter types.
uint32_t param_count =
consume_count("param count", kV8MaxWasmFunctionParams);
// We don't know the return count yet, so decode the parameters into a
// temporary SmallVector. This needs to be copied over into the permanent
// storage later.
base::SmallVector<ValueType, 8> params{param_count};
for (uint32_t i = 0; i < param_count; ++i) {
params[i] = consume_value_type();
if (tracer_) tracer_->NextLineIfFull();
}
if (tracer_) tracer_->NextLineIfNonEmpty();
// Parse return types.
uint32_t return_count =
consume_count("return count", kV8MaxWasmFunctionReturns);
if (return_count > 1) {
detected_features_->add_multi_value();
}
// Now that we know the param count and the return count, we can allocate
// the permanent storage.
FunctionSig::Builder sig_builder{&module_->signature_storage, return_count,
param_count};
for (ValueType t : params) sig_builder.AddParam(t);
for (uint32_t i = 0; i < return_count; ++i) {
sig_builder.AddReturn(consume_value_type());
if (tracer_) tracer_->NextLineIfFull();
}
if (tracer_) tracer_->NextLineIfNonEmpty();
return sig_builder.Get();
}
const StructType* consume_struct(bool is_descriptor, SharedFlag is_shared) {
uint32_t field_count =
consume_count(", field count", kV8MaxWasmStructFields);
if (V8_UNLIKELY(failed())) return nullptr;
ValueType* fields =
module_->signature_storage.AllocateArray<ValueType>(field_count);
bool* mutabilities =
module_->signature_storage.AllocateArray<bool>(field_count);
for (uint32_t i = 0; ok() && i < field_count; ++i) {
fields[i] = consume_storage_type();
mutabilities[i] = consume_mutability();
if (tracer_) tracer_->NextLine();
}
if (V8_UNLIKELY(failed())) return nullptr;
uint32_t* offsets =
module_->signature_storage.AllocateArray<uint32_t>(field_count);
StructType* result = module_->signature_storage.New<StructType>(
field_count, offsets, fields, mutabilities, is_descriptor, is_shared);
result->InitializeOffsets();
return result;
}
const ArrayType* consume_array() {
ValueType element_type = consume_storage_type();
bool mutability = consume_mutability();
if (tracer_) tracer_->NextLine();
if (V8_UNLIKELY(failed())) return nullptr;
return module_->signature_storage.New<ArrayType>(element_type, mutability);
}
// Consume the attribute field of an exception.
uint32_t consume_exception_attribute() {
const uint8_t* pos = pc_;
uint32_t attribute = consume_u32v("exception attribute");
if (tracer_) tracer_->Bytes(pos, static_cast<uint32_t>(pc_ - pos));
if (V8_UNLIKELY(attribute != kExceptionAttribute)) {
errorf(pos, "exception attribute %u not supported", attribute);
return 0;
}
return attribute;
}
WasmElemSegment consume_element_segment_header() {
const uint8_t* pos = pc();
// The mask for the bit in the flag which indicates if the segment is
// active or not (0 is active).
constexpr uint8_t kNonActiveMask = 1 << 0;
// The mask for the bit in the flag which indicates:
// - for active tables, if the segment has an explicit table index field.
// - for non-active tables, whether the table is declarative (vs. passive).
constexpr uint8_t kHasTableIndexOrIsDeclarativeMask = 1 << 1;
// The mask for the bit in the flag which indicates if the functions of this
// segment are defined as function indices (0) or constant expressions (1).
constexpr uint8_t kExpressionsAsElementsMask = 1 << 2;
// The mask for the bit which denotes whether this segment is shared.
constexpr uint8_t kSharedFlag = 1 << 3;
constexpr uint8_t kFullMask = kNonActiveMask |
kHasTableIndexOrIsDeclarativeMask |
kExpressionsAsElementsMask | kSharedFlag;
uint32_t flag = consume_u32v("flag", tracer_);
if (V8_UNLIKELY((flag & kFullMask) != flag)) {
errorf(pos, "illegal flag value %u", flag);
return {};
}
SharedFlag is_shared = SharedFlag(flag & kSharedFlag);
if (V8_UNLIKELY(is_shared && !enabled_features_.has_shared())) {
errorf(pos, "illegal flag value %u", flag);
return {};
}
if (V8_UNLIKELY(is_shared)) {
// TODO(42204563): Support shared element segments.
error(pos, "shared element segments are not supported yet.");
return {};
}
if (is_shared) module_->has_shared_part = true;
const WasmElemSegment::Status status =
(flag & kNonActiveMask) ? (flag & kHasTableIndexOrIsDeclarativeMask)
? WasmElemSegment::kStatusDeclarative
: WasmElemSegment::kStatusPassive
: WasmElemSegment::kStatusActive;
const bool is_active = status == WasmElemSegment::kStatusActive;
if (tracer_) {
tracer_->Description(": ");
tracer_->Description(status == WasmElemSegment::kStatusActive ? "active"
: status == WasmElemSegment::kStatusPassive
? "passive,"
: "declarative,");
}
WasmElemSegment::ElementType element_type =
flag & kExpressionsAsElementsMask
? WasmElemSegment::kExpressionElements
: WasmElemSegment::kFunctionIndexElements;
const bool has_table_index =
is_active && (flag & kHasTableIndexOrIsDeclarativeMask);
uint32_t table_index = 0;
if (has_table_index) {
table_index = consume_u32v(", table index", tracer_);
if (tracer_) tracer_->Description(table_index);
}
if (V8_UNLIKELY(is_active && table_index >= module_->tables.size())) {
// If `has_table_index`, we have an explicit table index. Otherwise, we
// always have the implicit table index 0.
errorf(pos, "out of bounds%s table index %u",
has_table_index ? "" : " implicit", table_index);
return {};
}
ValueType table_type =
is_active ? module_->tables[table_index].type : kWasmBottom;
ConstantExpression offset;
if (is_active) {
if (tracer_) {
tracer_->Description(", offset:");
tracer_->NextLine();
}
offset = consume_init_expr(
module_.get(),
module_->tables[table_index].is_table64() ? kWasmI64 : kWasmI32);
// Failed to parse offset initializer, return early.
if (V8_UNLIKELY(failed())) return {};
}
// Denotes an active segment without table index, type, or element kind.
const bool backwards_compatible_mode =
is_active && !(flag & kHasTableIndexOrIsDeclarativeMask);
ValueType type;
if (element_type == WasmElemSegment::kExpressionElements) {
if (backwards_compatible_mode) {
type = kWasmFuncRef;
} else {
if (tracer_) tracer_->Description(" element type:");
type = consume_value_type(module_.get());
if (V8_UNLIKELY(failed())) return {};
}
} else {
if (!backwards_compatible_mode) {
// We have to check that there is an element kind of type Function. All
// other element kinds are not valid yet.
if (tracer_) tracer_->Description(" ");
uint8_t val = consume_u8("element type: function", tracer_);
if (V8_UNLIKELY(static_cast<ImportExportKindCode>(val) !=
kExternalFunction)) {
errorf(pos, "illegal element kind 0x%x. Must be 0x%x", val,
kExternalFunction);
return {};
}
}
type = kWasmFuncRef.AsNonNull();
}
if (V8_UNLIKELY(is_active &&
!IsSubtypeOf(type, table_type, this->module_.get()))) {
errorf(pos,
"Element segment of type %s is not a subtype of referenced "
"table %u (of type %s)",
type.name().c_str(), table_index, table_type.name().c_str());
return {};
}
// TODO(14616): Is this too restrictive?
if (V8_UNLIKELY(is_active &&
(is_shared != module_->tables[table_index].shared))) {
error(pos,
"Shared (resp. non-shared) element segments must refer to shared "
"(resp. non-shared) tables");
return {};
}
uint32_t num_elem =
consume_count(" number of elements", max_table_init_entries());
if (is_active) {
return {is_shared, type, table_index, std::move(offset),
element_type, num_elem, pc_offset()};
} else {
return {status, is_shared, type, element_type, num_elem, pc_offset()};
}
}
DataSegmentHeader consume_data_segment_header() {
const uint8_t* pos = pc();
uint32_t flag = consume_u32v("flag", tracer_);
if (V8_UNLIKELY(flag & ~0b1011)) {
errorf(pos, "illegal flag value %u", flag);
return {};
}
uint32_t status_flag = flag & 0b11;
if (tracer_) {
tracer_->Description(": ");
tracer_->Description(
status_flag == SegmentFlags::kActiveNoIndex ? "active no index"
: status_flag == SegmentFlags::kPassive ? "passive"
: status_flag == SegmentFlags::kActiveWithIndex ? "active with index"
: "unknown");
}
if (V8_UNLIKELY(status_flag != SegmentFlags::kActiveNoIndex &&
status_flag != SegmentFlags::kPassive &&
status_flag != SegmentFlags::kActiveWithIndex)) {
errorf(pos, "illegal flag value %u", flag);
return {};
}
SharedFlag is_shared = SharedFlag(flag & 0b1000);
if (V8_UNLIKELY(is_shared && !enabled_features_.has_shared())) {
errorf(pos, "illegal flag value %u.", flag);
return {};
}
if (V8_UNLIKELY(is_shared)) {
// TODO(42204563): Support shared data segments.
error(pos, "shared data segments are not supported yet.");
return {};
}
if (is_shared) module_->has_shared_part = true;
if (tracer_) {
if (is_shared) tracer_->Description(" shared");
tracer_->NextLine();
}
bool is_active = status_flag == SegmentFlags::kActiveNoIndex ||
status_flag == SegmentFlags::kActiveWithIndex;
uint32_t mem_index = status_flag == SegmentFlags::kActiveWithIndex
? consume_u32v("memory index", tracer_)
: 0;
ConstantExpression offset;
if (is_active) {
size_t num_memories = module_->memories.size();
if (V8_UNLIKELY(mem_index >= num_memories)) {
errorf(pos,
"invalid memory index %u for data section (having %zu memor%s)",
mem_index, num_memories, num_memories == 1 ? "y" : "ies");
return {};
}
ValueType expected_type =
module_->memories[mem_index].is_memory64() ? kWasmI64 : kWasmI32;
offset = consume_init_expr(module_.get(), expected_type);
}
return {is_active, is_shared, mem_index, offset};
}
uint32_t consume_element_func_index(WasmModule* module, ValueType expected) {
WasmFunction* func = nullptr;
const uint8_t* initial_pc = pc();
uint32_t index = consume_func_index(module, &func);
if (tracer_) tracer_->NextLine();
if (V8_UNLIKELY(failed())) return index;
DCHECK_NOT_NULL(func);
DCHECK_EQ(index, func->func_index);
ValueType entry_type =
ValueType::Ref(func->sig_index, module->type(func->sig_index).is_shared,
RefTypeKind::kFunction);
if (V8_LIKELY(expected == kWasmFuncRef &&
!enabled_features_.has_shared())) {
DCHECK(module->type(func->sig_index).kind == TypeDefinition::kFunction);
DCHECK(IsSubtypeOf(entry_type, expected, module));
} else if (V8_UNLIKELY(!IsSubtypeOf(entry_type, expected, module))) {
errorf(initial_pc,
"Invalid type in element entry: expected %s, got %s instead.",
expected.name().c_str(), entry_type.name().c_str());
return index;
}
func->declared = true;
return index;
}
const WasmEnabledFeatures enabled_features_;
WasmDetectedFeatures* const detected_features_;
const std::shared_ptr<WasmModule> module_;
const uint8_t* module_start_ = nullptr;
const uint8_t* module_end_ = nullptr;
ITracer* tracer_;
// The type section is the first section in a module.
uint8_t next_ordered_section_ = kFirstSectionInModule;
// We store next_ordered_section_ as uint8_t instead of SectionCode so that
// we can increment it. This static_assert should make sure that SectionCode
// does not get bigger than uint8_t accidentally.
static_assert(sizeof(ModuleDecoderImpl::next_ordered_section_) ==
sizeof(SectionCode),
"type mismatch");
uint32_t seen_unordered_sections_ = 0;
static_assert(kBitsPerByte *
sizeof(ModuleDecoderImpl::seen_unordered_sections_) >
kLastKnownModuleSection,
"not enough bits");
AccountingAllocator allocator_;
// We pass this {Zone} to the temporary {WasmFullDecoder} we allocate during
// each call to {consume_init_expr}, and reset it after each such call. This
// has been found to improve performance a bit over allocating a new {Zone}
// each time.
Zone init_expr_zone_{&allocator_, "constant expr. zone"};
// Instruction traces are decoded in DecodeInstTraceSection as a 3-tuple
// of the function index, function offset, and mark_id. In DecodeCodeSection,
// after the functions have been decoded this is translated to pairs of module
// offsets and mark ids.
std::vector<std::tuple<uint32_t, uint32_t, uint32_t>> inst_traces_;
};
} // namespace v8::internal::wasm
#undef TRACE
#endif // V8_WASM_MODULE_DECODER_IMPL_H_