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// 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.
#if !V8_ENABLE_WEBASSEMBLY
#error This header should only be included if WebAssembly is enabled.
#endif // !V8_ENABLE_WEBASSEMBLY
#ifndef V8_WASM_MODULE_DECODER_IMPL_H_
#define V8_WASM_MODULE_DECODER_IMPL_H_
#include "src/base/platform/wrappers.h"
#include "src/logging/counters.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-engine.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)
constexpr char kNameString[] = "name";
constexpr char kSourceMappingURLString[] = "sourceMappingURL";
constexpr char kInstTraceString[] = "metadata.code.trace_inst";
constexpr char kCompilationHintsString[] = "compilationHints";
constexpr char kBranchHintsString[] = "metadata.code.branch_hint";
constexpr char kDebugInfoString[] = ".debug_info";
constexpr char kExternalDebugInfoString[] = "external_debug_info";
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";
}
return "unknown";
}
inline bool validate_utf8(Decoder* decoder, WireBytesRef string) {
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);
uint32_t length = decoder->consume_u32v(" length:", tracer);
if (tracer) {
tracer->Description(length);
tracer->NextLine();
}
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 (!unibrow::Utf8::ValidateEncoding(string_start, length)) {
decoder->errorf(string_start, "%s: no valid UTF-8 string", name);
}
break;
case unibrow::Utf8Variant::kWtf8:
if (!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 (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(kCompilationHintsString),
kCompilationHintsSectionCode},
{base::StaticCharVector(kBranchHintsString), kBranchHintsSectionCode},
{base::StaticCharVector(kDebugInfoString), kDebugInfoSectionCode},
{base::StaticCharVector(kExternalDebugInfoString),
kExternalDebugInfoSectionCode}};
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_);
}
const uint8_t* section_end() const { return section_end_; }
// 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 (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(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 (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 the known "name", "sourceMappingURL", or "compilationHints"
// section.
// 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 (!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.length(), 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(WasmFeatures enabled_features,
base::Vector<const uint8_t> wire_bytes, ModuleOrigin origin,
PopulateExplicitRecGroups populate_explicit_rec_groups =
kDoNotPopulateExplicitRecGroups,
ITracer* tracer = ITracer::NoTrace)
: Decoder(wire_bytes),
enabled_features_(enabled_features),
module_(std::make_shared<WasmModule>(origin)),
module_start_(wire_bytes.begin()),
module_end_(wire_bytes.end()),
populate_explicit_rec_groups_(populate_explicit_rec_groups),
tracer_(tracer) {}
void onFirstError() override {
pc_ = end_; // On error, terminate section decoding loop.
}
void DecodeModuleHeader(base::Vector<const uint8_t> bytes) {
if (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 (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 (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 (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 (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 (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 (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:
// If there is an explicit source map, prefer it over DWARF info.
if (module_->debug_symbols.type == WasmDebugSymbols::Type::None) {
module_->debug_symbols = {WasmDebugSymbols::Type::EmbeddedDWARF, {}};
}
consume_bytes(static_cast<uint32_t>(end_ - start_), ".debug_info");
break;
case kExternalDebugInfoSectionCode:
DecodeExternalDebugInfoSection();
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 kCompilationHintsSectionCode:
if (enabled_features_.has_compilation_hints()) {
DecodeCompilationHintsSection();
} 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 kBranchHintsSectionCode:
if (enabled_features_.has_branch_hinting()) {
DecodeBranchHintsSection();
} 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 "
"--experimental-wasm-stringref)",
SectionName(section_code));
}
break;
default:
errorf(pc(), "unexpected section <%s>", SectionName(section_code));
return;
}
if (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";
default: return "unknown";
// clang-format on
}
}
TypeDefinition consume_base_type_definition() {
DCHECK(enabled_features_.has_gc());
uint8_t kind = consume_u8(" kind: ", tracer_);
if (tracer_) tracer_->Description(TypeKindName(kind));
switch (kind) {
case kWasmFunctionTypeCode: {
const FunctionSig* sig = consume_sig(&module_->signature_zone);
return {sig, kNoSuperType, v8_flags.wasm_final_types};
}
case kWasmStructTypeCode: {
module_->is_wasm_gc = true;
const StructType* type = consume_struct(&module_->signature_zone);
return {type, kNoSuperType, v8_flags.wasm_final_types};
}
case kWasmArrayTypeCode: {
module_->is_wasm_gc = true;
const ArrayType* type = consume_array(&module_->signature_zone);
return {type, kNoSuperType, v8_flags.wasm_final_types};
}
default:
if (tracer_) tracer_->NextLine();
errorf(pc() - 1, "unknown type form: %d", kind);
return {};
}
}
TypeDefinition consume_subtype_definition() {
DCHECK(enabled_features_.has_gc());
uint8_t kind = read_u8<Decoder::FullValidationTag>(pc(), "type kind");
if (kind == kWasmSubtypeCode || kind == kWasmSubtypeFinalCode) {
module_->is_wasm_gc = true;
bool is_final =
v8_flags.wasm_final_types && 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;
if (supertype_count == 1) {
supertype = consume_u32v("supertype", tracer_);
if (supertype >= kV8MaxWasmTypes) {
errorf(
"supertype %u is greater than the maximum number of type "
"definitions %zu supported by V8",
supertype, kV8MaxWasmTypes);
return {};
}
if (tracer_) {
tracer_->Description(supertype);
tracer_->NextLine();
}
}
TypeDefinition type = consume_base_type_definition();
type.supertype = supertype;
type.is_final = is_final;
return type;
} else {
return consume_base_type_definition();
}
}
void DecodeTypeSection() {
TypeCanonicalizer* type_canon = GetTypeCanonicalizer();
uint32_t types_count = consume_count("types count", kV8MaxWasmTypes);
// Non wasm-gc type section decoding.
if (!enabled_features_.has_gc()) {
module_->types.resize(types_count);
module_->isorecursive_canonical_type_ids.resize(types_count);
for (uint32_t i = 0; i < types_count; ++i) {
TRACE("DecodeSignature[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
uint8_t opcode =
read_u8<FullValidationTag>(pc(), "signature definition");
if (tracer_) {
tracer_->Bytes(pc_, 1);
tracer_->TypeOffset(pc_offset());
tracer_->Description(" kind: ");
tracer_->Description(TypeKindName(opcode));
tracer_->NextLine();
}
switch (opcode) {
case kWasmFunctionTypeCode: {
consume_bytes(1, "function");
const FunctionSig* sig = consume_sig(&module_->signature_zone);
if (!ok()) break;
module_->types[i] = {sig, kNoSuperType, v8_flags.wasm_final_types};
type_canon->AddRecursiveGroup(module_.get(), 1, i);
break;
}
case kWasmArrayTypeCode:
case kWasmStructTypeCode:
case kWasmSubtypeCode:
case kWasmSubtypeFinalCode:
case kWasmRecursiveTypeGroupCode:
errorf(
"Unknown type code 0x%02x, enable with --experimental-wasm-gc",
opcode);
return;
default:
errorf("Expected signature definition 0x%02x, got 0x%02x",
kWasmFunctionTypeCode, opcode);
return;
}
}
return;
}
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();
if (kind == kWasmRecursiveTypeGroupCode) {
module_->is_wasm_gc = true;
consume_bytes(1, "rec. group definition", tracer_);
if (tracer_) tracer_->NextLine();
uint32_t group_size =
consume_count("recursive group size", kV8MaxWasmTypes);
if (initial_size + group_size > kV8MaxWasmTypes) {
errorf(pc(), "Type definition count exceeds maximum %zu",
kV8MaxWasmTypes);
return;
}
if (populate_explicit_rec_groups_ == kPopulateExplicitRecGroups) {
module_->explicit_recursive_type_groups.emplace(
static_cast<uint32_t>(module_->types.size()), group_size);
}
// 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);
module_->isorecursive_canonical_type_ids.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();
if (ok()) module_->types[initial_size + j] = type;
}
if (ok()) {
type_canon->AddRecursiveGroup(module_.get(), group_size,
static_cast<uint32_t>(initial_size));
}
if (tracer_) {
tracer_->Description("end of rec. group");
tracer_->NextLine();
}
} else {
if (tracer_) tracer_->TypeOffset(pc_offset());
// Similarly to above, we need to resize types for a group of size 1.
module_->types.resize(initial_size + 1);
module_->isorecursive_canonical_type_ids.resize(initial_size + 1);
TypeDefinition type = consume_subtype_definition();
if (ok()) {
module_->types[initial_size] = type;
type_canon->AddRecursiveGroup(module_.get(), 1);
}
}
}
// Check validity of explicitly defined supertypes and propagate subtyping
// depth.
const WasmModule* module = module_.get();
for (uint32_t i = 0; ok() && i < module_->types.size(); ++i) {
uint32_t explicit_super = module_->supertype(i);
if (explicit_super == kNoSuperType) continue;
if (explicit_super >= module_->types.size()) {
errorf("type %u: supertype %u out of bounds", i, explicit_super);
continue;
}
if (explicit_super >= i) {
errorf("type %u: forward-declared supertype %u", i, explicit_super);
continue;
}
uint32_t depth = module->types[explicit_super].subtyping_depth + 1;
module_->types[i].subtyping_depth = depth;
DCHECK_GE(depth, 0);
if (depth > kV8MaxRttSubtypingDepth) {
errorf("type %u: subtyping depth is greater than allowed", i);
continue;
}
// This check is technically redundant; we include for the improved error
// message.
if (module->types[explicit_super].is_final) {
errorf("type %u extends final type %u", i, explicit_super);
continue;
}
if (!ValidSubtypeDefinition(i, explicit_super, module, module)) {
errorf("type %u has invalid explicit supertype %u", i, explicit_super);
continue;
}
}
}
void DecodeImportSection() {
uint32_t import_table_count =
consume_count("imports count", kV8MaxWasmImports);
module_->import_table.reserve(import_table_count);
for (uint32_t i = 0; ok() && i < import_table_count; ++i) {
TRACE("DecodeImportTable[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
if (tracer_) tracer_->ImportOffset(pc_offset());
module_->import_table.push_back({
{0, 0}, // module_name
{0, 0}, // field_name
kExternalFunction, // kind
0 // index
});
WasmImport* import = &module_->import_table.back();
const uint8_t* pos = pc_;
import->module_name = consume_utf8_string(this, "module name", tracer_);
import->field_name = consume_utf8_string(this, "field name", tracer_);
import->kind =
static_cast<ImportExportKindCode>(consume_u8("kind: ", tracer_));
if (tracer_) tracer_->Description(ExternalKindName(import->kind));
switch (import->kind) {
case kExternalFunction: {
// ===== Imported function ===========================================
import->index = static_cast<uint32_t>(module_->functions.size());
module_->num_imported_functions++;
module_->functions.push_back({nullptr, // sig
import->index, // func_index
0, // sig_index
{0, 0}, // code
true, // imported
false, // exported
false}); // declared
WasmFunction* function = &module_->functions.back();
function->sig_index =
consume_sig_index(module_.get(), &function->sig);
break;
}
case kExternalTable: {
// ===== Imported table ==============================================
import->index = static_cast<uint32_t>(module_->tables.size());
module_->num_imported_tables++;
module_->tables.emplace_back();
WasmTable* table = &module_->tables.back();
table->imported = true;
const uint8_t* type_position = pc();
ValueType type = consume_value_type();
if (!type.is_object_reference()) {
errorf(type_position, "Invalid table type %s", type.name().c_str());
break;
}
table->type = type;
consume_table_flags("element count", &table->has_maximum_size);
consume_resizable_limits(
"element count", "elements", std::numeric_limits<uint32_t>::max(),
&table->initial_size, table->has_maximum_size,
std::numeric_limits<uint32_t>::max(), &table->maximum_size,
k32BitLimits);
break;
}
case kExternalMemory: {
// ===== Imported memory =============================================
static_assert(kV8MaxWasmMemories <= kMaxUInt32);
if (!enabled_features_.has_multi_memory()) {
if (!module_->memories.empty()) {
error(
"At most one imported memory is supported (pass "
"--experimental-wasm-multi-memory to allow more "
"memories)");
break;
}
} else if (module_->memories.size() >= kV8MaxWasmMemories - 1) {
errorf("At most %u imported memories are supported",
kV8MaxWasmMemories);
break;
}
uint32_t mem_index = static_cast<uint32_t>(module_->memories.size());
import->index = mem_index;
module_->memories.emplace_back();
WasmMemory* external_memory = &module_->memories.back();
external_memory->index = mem_index;
consume_memory_flags(&external_memory->is_shared,
&external_memory->is_memory64,
&external_memory->has_maximum_pages);
uint32_t max_pages = external_memory->is_memory64
? kSpecMaxMemory64Pages
: kSpecMaxMemory32Pages;
consume_resizable_limits(
"memory", "pages", max_pages, &external_memory->initial_pages,
external_memory->has_maximum_pages, max_pages,
&external_memory->maximum_pages,
external_memory->is_memory64 ? k64BitLimits : k32BitLimits);
break;
}
case kExternalGlobal: {
// ===== Imported global =============================================
import->index = static_cast<uint32_t>(module_->globals.size());
module_->num_imported_globals++;
module_->globals.push_back({kWasmVoid, false, {}, {0}, true, false});
WasmGlobal* global = &module_->globals.back();
global->type = consume_value_type();
global->mutability = consume_mutability();
if (global->mutability) {
module_->num_imported_mutable_globals++;
}
if (tracer_) tracer_->NextLine();
break;
}
case kExternalTag: {
// ===== Imported tag ================================================
import->index = static_cast<uint32_t>(module_->tags.size());
module_->num_imported_tags++;
const WasmTagSig* tag_sig = nullptr;
consume_exception_attribute(); // Attribute ignored for now.
uint32_t sig_index = consume_tag_sig_index(module_.get(), &tag_sig);
module_->tags.emplace_back(tag_sig, sig_index);
break;
}
default:
errorf(pos, "unknown import kind 0x%02x", import->kind);
break;
}
}
UpdateComputedMemoryInformation();
module_->type_feedback.well_known_imports.Initialize(
module_->num_imported_functions);
if (tracer_) tracer_->ImportsDone();
}
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;
// Also initialize the {validated_functions} bitset here, now that we know
// the number of declared functions.
DCHECK_NULL(module_->validated_functions);
module_->validated_functions =
std::make_unique<std::atomic<uint8_t>[]>((functions_count + 7) / 8);
if (is_asmjs_module(module_.get())) {
// Mark all asm.js functions as valid by design (it's faster to do this
// here than to check this in {WasmModule::function_was_validated}).
std::fill_n(module_->validated_functions.get(), (functions_count + 7) / 8,
0xff);
}
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 (!ok()) return;
}
}
void DecodeTableSection() {
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 (enabled_features_.has_typed_funcref() &&
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 (reserved != 0) {
error(type_position, "Reserved byte must be 0x00");
break;
}
type_position++;
}
ValueType table_type = consume_value_type();
if (!table_type.is_object_reference()) {
error(type_position, "Only reference types can be used as table types");
break;
}
if (!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 elements", &table->has_maximum_size);
consume_resizable_limits("table elements", "elements",
std::numeric_limits<uint32_t>::max(),
&table->initial_size, table->has_maximum_size,
std::numeric_limits<uint32_t>::max(),
&table->maximum_size, 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();
if (enabled_features_.has_multi_memory()) {
DCHECK_GE(kV8MaxWasmMemories, imported_memories);
if (memory_count > kV8MaxWasmMemories - imported_memories) {
errorf(mem_count_pc,
"Exceeding maximum number of memories (%u; declared %u, "
"imported %zu)",
kV8MaxWasmMemories, memory_count, imported_memories);
}
} else {
DCHECK_GE(1, imported_memories);
if (imported_memories + memory_count > 1) {
errorf(mem_count_pc,
"At most one memory is supported (declared %u, imported %zu); "
"pass --experimental-wasm-multi-memory to allow more memories",
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->is_shared, &memory->is_memory64,
&memory->has_maximum_pages);
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);
}
UpdateComputedMemoryInformation();
}
void UpdateComputedMemoryInformation() {
for (WasmMemory& memory : module_->memories) {
UpdateComputedInformation(&memory, module_->origin);
}
}
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());
ValueType type = consume_value_type();
bool mutability = consume_mutability();
if (failed()) break;
ConstantExpression init = consume_init_expr(module_.get(), type);
module_->globals.push_back({type, mutability, init, {0}, false, false});
}
}
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();
}
module_->export_table.push_back({
{0, 0}, // name
kExternalFunction, // kind
0 // index
});
WasmExport* exp = &module_->export_table.back();
exp->name = consume_utf8_string(this, "field name", tracer_);
const uint8_t* pos = pc();
exp->kind =
static_cast<ImportExportKindCode>(consume_u8("kind: ", tracer_));
if (tracer_) {
tracer_->Description(ExternalKindName(exp->kind));
tracer_->Description(" ");
}
switch (exp->kind) {
case kExternalFunction: {
WasmFunction* func = nullptr;
exp->index = consume_func_index(module_.get(), &func);
if (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: {
exp->index = consume_u32v("memory index", tracer_);
size_t num_memories = module_->memories.size();
if (exp->index >= module_->memories.size()) {
errorf(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;
}
default:
errorf(pos, "invalid export kind 0x%02x", exp->kind);
break;
}
if (tracer_) tracer_->NextLine();
}
// Check for duplicate exports (except for asm.js).
if (ok() && module_->origin == kWasmOrigin &&
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 (!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 (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", v8_flags.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 (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 (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 (size > kV8MaxWasmFunctionSize) {
errorf(pos, "size %u > maximum function size %zu", size,
kV8MaxWasmFunctionSize);
return;
}
uint32_t offset = pc_offset();
consume_bytes(size, "function body");
if (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 (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};
if (tracer_) {
tracer_->FunctionBody(function, pc_ - (pc_offset() - offset));
}
}
bool CheckDataSegmentsCount(uint32_t data_segments_count) {
if (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;
}
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());
bool is_active;
uint32_t memory_index;
ConstantExpression dest_addr;
std::tie(is_active, memory_index, dest_addr) =
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 (failed()) break;
module_->data_segments.emplace_back(
is_active, memory_index, 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.type != WasmDebugSymbols::Type::SourceMap) {
module_->debug_symbols = {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 there is an explicit source map, prefer it over DWARF info.
if (inner.ok() &&
module_->debug_symbols.type != WasmDebugSymbols::Type::SourceMap) {
module_->debug_symbols = {WasmDebugSymbols::Type::ExternalDWARF, url};
set_seen_unordered_section(kExternalDebugInfoSectionCode);
}
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 (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 (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 (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 DecodeCompilationHintsSection() {
TRACE("DecodeCompilationHints module+%d\n", static_cast<int>(pc_ - start_));
// TODO(frgossen): Find a way to report compilation hint errors as warnings.
// All except first occurrence after function section and before code
// section are ignored.
const bool before_function_section =
next_ordered_section_ <= kFunctionSectionCode;
const bool after_code_section = next_ordered_section_ > kCodeSectionCode;
if (before_function_section || after_code_section ||
has_seen_unordered_section(kCompilationHintsSectionCode)) {
return;
}
set_seen_unordered_section(kCompilationHintsSectionCode);
// TODO(frgossen) Propagate errors to outer decoder in experimental phase.
// We should use an inner decoder later and propagate its errors as
// warnings.
Decoder& decoder = *this;
// Decoder decoder(start_, pc_, end_, buffer_offset_);
// Ensure exactly one compilation hint per function.
uint32_t hint_count = decoder.consume_u32v("compilation hint count");
if (hint_count != module_->num_declared_functions) {
decoder.errorf(decoder.pc(), "Expected %u compilation hints (%u found)",
module_->num_declared_functions, hint_count);
}
// Decode sequence of compilation hints.
if (decoder.ok()) {
module_->compilation_hints.reserve(hint_count);
}
for (uint32_t i = 0; decoder.ok() && i < hint_count; i++) {
TRACE("DecodeCompilationHints[%d] module+%d\n", i,
static_cast<int>(pc_ - start_));
// Compilation hints are encoded in one byte each.
// +-------+----------+---------------+----------+
// | 2 bit | 2 bit | 2 bit | 2 bit |
// | ... | Top tier | Baseline tier | Strategy |
// +-------+----------+---------------+----------+
uint8_t hint_byte = decoder.consume_u8("compilation hint");
if (!decoder.ok()) break;
// Validate the hint_byte.
// For the compilation strategy, all 2-bit values are valid. For the tier,
// only 0x0, 0x1, and 0x2 are allowed.
static_assert(
static_cast<int>(WasmCompilationHintTier::kDefault) == 0 &&
static_cast<int>(WasmCompilationHintTier::kBaseline) == 1 &&
static_cast<int>(WasmCompilationHintTier::kOptimized) == 2,
"The check below assumes that 0x03 is the only invalid 2-bit number "
"for a compilation tier");
if (((hint_byte >> 2) & 0x03) == 0x03 ||
((hint_byte >> 4) & 0x03) == 0x03) {
decoder.errorf(decoder.pc(),
"Invalid compilation hint %#04x (invalid tier 0x03)",
hint_byte);
break;
}
// Decode compilation hint.
WasmCompilationHint hint;
hint.strategy =
static_cast<WasmCompilationHintStrategy>(hint_byte & 0x03);
hint.baseline_tier =
static_cast<WasmCompilationHintTier>((hint_byte >> 2) & 0x03);
hint.top_tier =
static_cast<WasmCompilationHintTier>((hint_byte >> 4) & 0x03);
// Ensure that the top tier never downgrades a compilation result. If
// baseline and top tier are the same compilation will be invoked only
// once.
if (hint.top_tier < hint.baseline_tier &&
hint.top_tier != WasmCompilationHintTier::kDefault) {
decoder.errorf(decoder.pc(),
"Invalid compilation hint %#04x (forbidden downgrade)",
hint_byte);
}
// Happily accept compilation hint.
if (decoder.ok()) {
module_->compilation_hints.push_back(std::move(hint));
}
}
// If section was invalid reset compilation hints.
if (decoder.failed()) {
module_->compilation_hints.clear();
}
// @TODO(frgossen) Skip the whole compilation hints section in the outer
// decoder if inner decoder was used.
// consume_bytes(static_cast<uint32_t>(end_ - start_), nullptr);
}
void DecodeBranchHintsSection() {
TRACE("DecodeBranchHints module+%d\n", static_cast<int>(pc_ - start_));
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 (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 (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 (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()));
WasmBranchHint hint;
switch (br_dir) {
case 0:
hint = WasmBranchHint::kUnlikely;
break;
case 1:
hint = WasmBranchHint::kLikely;
break;
default:
hint = WasmBranchHint::kNoHint;
inner.errorf(inner.pc(), "Invalid branch hint %#x", br_dir);
break;
}
if (!inner.ok()) {
break;
}
func_branch_hints.insert(br_off, hint);
}
if (!inner.ok()) {
break;
}
branch_hints.emplace(func_idx, std::move(func_branch_hints));
}
// Extra unexpected bytes are an error.
if (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);
}
}
// Skip the whole branch hints 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.
uint32_t 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 (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 (!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 (!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());
}
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 (wire_bytes.size() > max_size) {
return ModuleResult{WasmError{0, "size > maximum module size (%zu): %zu",
max_size, wire_bytes.size()}};
}
DecodeModuleHeader(wire_bytes);
if (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 (!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 (section_iterator_decoder.failed()) {
return section_iterator_decoder.toResult(nullptr);
}
ModuleResult result = FinishDecoding();
if (!result.failed() && validate_functions) {
// Pass nullptr for an "empty" filter function.
if (WasmError validation_error = ValidateFunctions(
module_.get(), enabled_features_, wire_bytes, nullptr)) {
result = ModuleResult{validation_error};
}
}
if (v8_flags.dump_wasm_module) DumpModule(wire_bytes, result.ok());
return result;
}
// Decodes a single anonymous function starting at {start_}.
FunctionResult DecodeSingleFunctionForTesting(Zone* zone,
ModuleWireBytes wire_bytes,
const WasmModule* module) {
DCHECK(ok());
pc_ = start_;
expect_u8("type form", kWasmFunctionTypeCode);
WasmFunction function;
function.sig = consume_sig(zone);
function.code = {off(pc_), static_cast<uint32_t>(end_ - pc_)};
if (!ok()) return FunctionResult{std::move(error_)};
FunctionBody body{function.sig, off(pc_), pc_, end_};
WasmFeatures unused_detected_features;
DecodeResult result = ValidateFunctionBody(enabled_features_, module,
&unused_detected_features, body);
if (result.failed()) return FunctionResult{std::move(result).error()};
return FunctionResult{std::make_unique<WasmFunction>(function)};
}
// Decodes a single function signature at {start}.
const FunctionSig* DecodeFunctionSignature(Zone* zone, const uint8_t* start) {
pc_ = start;
if (!expect_u8("type form", kWasmFunctionTypeCode)) return nullptr;
const FunctionSig* result = consume_sig(zone);
return ok() ? result : nullptr;
}
ConstantExpression DecodeInitExprForTesting(ValueType expected) {
return consume_init_expr(module_.get(), expected);
}
// 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_offset = 0;
uint32_t tagged_offset = 0;
uint32_t num_imported_mutable_globals = 0;
for (WasmGlobal& global : module->globals) {
if (global.mutability && global.imported) {
global.index = num_imported_mutable_globals++;
} else if (global.type.is_reference()) {
global.offset = tagged_offset;
// All entries in the tagged_globals_buffer have size 1.
tagged_offset++;
} else {
int size = global.type.value_kind_size();
untagged_offset = (untagged_offset + size - 1) & ~(size - 1); // align
global.offset = untagged_offset;
untagged_offset += size;
}
}
module->untagged_globals_buffer_size = untagged_offset;
module->tagged_globals_buffer_size = tagged_offset;
}
uint32_t consume_sig_index(WasmModule* module, const FunctionSig** sig) {
const uint8_t* pos = pc_;
uint32_t sig_index = consume_u32v("signature index");
if (tracer_) tracer_->Bytes(pos, static_cast<uint32_t>(pc_ - pos));
if (!module->has_signature(sig_index)) {
errorf(pos, "no signature at index %u (%d %s)", sig_index,
static_cast<int>(module->types.size()),
enabled_features_.has_gc() ? "types" : "signatures");
*sig = nullptr;
return 0;
}
*sig = module->signature(sig_index);
if (tracer_) {
tracer_->Description(*sig);
tracer_->NextLine();
}
return sig_index;
}
uint32_t consume_tag_sig_index(WasmModule* module, const FunctionSig** sig) {
const uint8_t* pos = pc_;
uint32_t sig_index = consume_sig_index(module, sig);
if (*sig && (*sig)->return_count() != 0) {
errorf(pos, "tag signature %u has non-void return", sig_index);
*sig = nullptr;
return 0;
}
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 (count > maximum) {
errorf(p, "%s of %u exceeds internal limit of %zu", name, count, maximum);
return static_cast<uint32_t>(maximum);
}
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(index);
if (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;
}
void consume_table_flags(const char* name, bool* has_maximum_out) {
if (tracer_) tracer_->Bytes(pc_, 1);
uint8_t flags = consume_u8("table limits flags");
if (tracer_) {
tracer_->Description(flags == kNoMaximum ? " no maximum"
: " with maximum");
tracer_->NextLine();
}
static_assert(kNoMaximum == 0 && kWithMaximum == 1);
*has_maximum_out = flags == kWithMaximum;
if (V8_UNLIKELY(flags > kWithMaximum)) {
errorf(pc() - 1, "invalid %s limits flags", name);
}
}
void consume_memory_flags(bool* is_shared_out, bool* is_memory64_out,
bool* has_maximum_out) {
if (tracer_) tracer_->Bytes(pc_, 1);
uint8_t flags = consume_u8("memory limits flags");
// Flags 0..7 are valid (3 bits).
if (flags & ~0x7) {
errorf(pc() - 1, "invalid memory limits flags 0x%x", flags);
}
// Decode the three bits.
bool has_maximum = flags & 0x1;
bool is_shared = flags & 0x2;
bool is_memory64 = flags & 0x4;
// Store into output parameters.
*has_maximum_out = has_maximum;
*is_shared_out = is_shared;
*is_memory64_out = is_memory64;
// V8 does not support shared memory without a maximum.
if (is_shared && !has_maximum) {
error(pc() - 1, "shared memory must have a maximum defined");
}
if (is_memory64 && !enabled_features_.has_memory64()) {
errorf(pc() - 1,
"invalid memory limits flags 0x%x (enable via "
"--experimental-wasm-memory64)",
flags);
}
// Tracing.
if (tracer_) {
if (is_shared) tracer_->Description(" shared");
if (is_memory64) tracer_->Description(" mem64");
tracer_->Description(has_maximum ? " with maximum" : " no maximum");
tracer_->NextLine();
}
}
enum ResizableLimitsType : bool { k32BitLimits, k64BitLimits };
void consume_resizable_limits(const char* name, const char* units,
uint32_t max_initial, uint32_t* initial,
bool has_maximum, uint32_t max_maximum,
uint32_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 (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 (maximum_64 > max_maximum) {
errorf(pos,
"maximum %s size (%" PRIu64
" %s) is larger than implementation limit (%u %s)",
name, maximum_64, units, max_maximum, units);
}
if (maximum_64 < *initial) {
errorf(pos,
"maximum %s size (%" PRIu64 " %s) is less than initial (%u %s)",
name, maximum_64, units, *initial, units);
}
*maximum = static_cast<uint32_t>(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 (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) {
// 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 (!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 {};
}
ValueType type =
enabled_features_.has_typed_funcref()
? ValueType::Ref(module->functions[index].sig_index)
: kWasmFuncRef;
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_);
value_type_reader::ValidateHeapType<FullValidationTag>(this, pc_,
module, type);
if (V8_UNLIKELY(failed())) return {};
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.representation());
}
break;
}
default:
break;
}
#undef TYPE_CHECK
auto sig = FixedSizeSignature<ValueType>::Returns(expected);
FunctionBody body(&sig, buffer_offset_, pc_, end_);
WasmFeatures detected;
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_) {
tracer_->InitializerExpression(pc_, decoder.end(), expected);
}
this->pc_ = decoder.end();
if (decoder.failed()) {
error(decoder.error().offset(), decoder.error().message().c_str());
return {};
}
if (!decoder.interface().end_found()) {
error("constant expression is missing 'end'");
return {};
}
return ConstantExpression::WireBytes(
offset, static_cast<uint32_t>(decoder.end() - decoder.start()));
}
// 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 (val > 1) error(pc_ - 1, "invalid mutability");
return val != 0;
}
ValueType consume_value_type() {
auto [result, length] =
value_type_reader::read_value_type<FullValidationTag>(
this, pc_,
module_->origin == kWasmOrigin ? enabled_features_
: WasmFeatures::None());
value_type_reader::ValidateValueType<FullValidationTag>(
this, pc_, module_.get(), result);
if (tracer_) {
tracer_->Bytes(pc_, length);
tracer_->Description(result);
}
consume_bytes(length, "value type");
return result;
}
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(Zone* zone) {
if (tracer_) tracer_->NextLine();
// Parse parameter types.
uint32_t param_count =
consume_count("param count", kV8MaxWasmFunctionParams);
if (failed()) return nullptr;
std::vector<ValueType> params;
for (uint32_t i = 0; ok() && i < param_count; ++i) {
params.push_back(consume_value_type());
if (tracer_) tracer_->NextLineIfFull();
}
if (tracer_) tracer_->NextLineIfNonEmpty();
if (failed()) return nullptr;
// Parse return types.
std::vector<ValueType> returns;
uint32_t return_count =
consume_count("return count", kV8MaxWasmFunctionReturns);
if (failed()) return nullptr;
for (uint32_t i = 0; ok() && i < return_count; ++i) {
returns.push_back(consume_value_type());
if (tracer_) tracer_->NextLineIfFull();
}
if (tracer_) tracer_->NextLineIfNonEmpty();
if (failed()) return nullptr;
// FunctionSig stores the return types first.
ValueType* buffer =
zone->AllocateArray<ValueType>(param_count + return_count);
uint32_t b = 0;
for (uint32_t i = 0; i < return_count; ++i) buffer[b++] = returns[i];
for (uint32_t i = 0; i < param_count; ++i) buffer[b++] = params[i];
return zone->New<FunctionSig>(return_count, param_count, buffer);
}
const StructType* consume_struct(Zone* zone) {
uint32_t field_count =
consume_count(", field count", kV8MaxWasmStructFields);
if (failed()) return nullptr;
ValueType* fields = zone->AllocateArray<ValueType>(field_count);
bool* mutabilities = zone->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 (failed()) return nullptr;
uint32_t* offsets = zone->AllocateArray<uint32_t>(field_count);
StructType* result =
zone->New<StructType>(field_count, offsets, fields, mutabilities);
result->InitializeOffsets();
return result;
}
const ArrayType* consume_array(Zone* zone) {
ValueType element_type = consume_storage_type();
bool mutability = consume_mutability();
if (tracer_) tracer_->NextLine();
if (failed()) return nullptr;
return zone->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 (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;
constexpr uint8_t kFullMask = kNonActiveMask |
kHasTableIndexOrIsDeclarativeMask |
kExpressionsAsElementsMask;
uint32_t flag = consume_u32v("flag: ", tracer_);
if ((flag & kFullMask) != flag) {
errorf(pos, "illegal flag value %u. Must be between 0 and 7", flag);
return {};
}
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(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())) {
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(), kWasmI32);
// Failed to parse offset initializer, return early.
if (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();
if (failed()) return {};
}
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 {};
}
} 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.
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 {};
}
}
if (!is_active) {
// Declarative and passive segments without explicit type are funcref.
type = kWasmFuncRef;
} else {
type = table_type;
// Active segments with function indices must reference a function
// table. (Using struct / array indices doesn't provide any value
// as such an index doesn't refer to a unique object instance unlike
// functions.)
if (V8_UNLIKELY(
!IsSubtypeOf(table_type, kWasmFuncRef, this->module_.get()))) {
errorf(pos,
"An active element segment with function indices as elements "
"must reference a table of %s. Instead, table %u of type %s "
"is referenced.",
enabled_features_.has_typed_funcref()
? "a subtype of type funcref"
: "type funcref",
table_index, table_type.name().c_str());
return {};
}
}
}
uint32_t num_elem =
consume_count(" number of elements", max_table_init_entries());
if (is_active) {
return {type, table_index, std::move(offset),
element_type, num_elem, pc_offset()};
} else {
return {type, status, element_type, num_elem, pc_offset()};
}
}
std::tuple<bool, uint32_t, ConstantExpression> consume_data_segment_header() {
const uint8_t* pos = pc();
uint32_t flag = consume_u32v("flag: ", tracer_);
if (tracer_) {
tracer_->Description(
flag == SegmentFlags::kActiveNoIndex ? "active no index"
: flag == SegmentFlags::kPassive ? "passive"
: flag == SegmentFlags::kActiveWithIndex ? "active with index"
: "unknown");
tracer_->NextLine();
}
// Some flag values are only valid for specific proposals.
if (flag != SegmentFlags::kActiveNoIndex &&
flag != SegmentFlags::kPassive &&
flag != SegmentFlags::kActiveWithIndex) {
errorf(pos, "illegal flag value %u. Must be 0, 1, or 2", flag);
return {};
}
bool is_active = flag == SegmentFlags::kActiveNoIndex ||
flag == SegmentFlags::kActiveWithIndex;
uint32_t mem_index = flag == SegmentFlags::kActiveWithIndex
? consume_u32v("memory index", tracer_)
: 0;
ConstantExpression offset;
if (is_active) {
size_t num_memories = module_->memories.size();
if (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, 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 (failed()) return index;
DCHECK_NOT_NULL(func);
DCHECK_EQ(index, func->func_index);
ValueType entry_type = ValueType::Ref(func->sig_index);
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 WasmFeatures enabled_features_;
const std::shared_ptr<WasmModule> module_;
const uint8_t* module_start_ = nullptr;
const uint8_t* module_end_ = nullptr;
PopulateExplicitRecGroups populate_explicit_rec_groups_;
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_;
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_
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