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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
*
* Copyright 2021 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef wasm_binary_h
#define wasm_binary_h
#include "mozilla/DebugOnly.h"
#include "mozilla/Maybe.h"
#include <type_traits>
#include "js/WasmFeatures.h"
#include "wasm/WasmCompile.h"
#include "wasm/WasmCompileArgs.h"
#include "wasm/WasmConstants.h"
#include "wasm/WasmTypeDecls.h"
#include "wasm/WasmTypeDef.h"
#include "wasm/WasmValType.h"
namespace js {
namespace wasm {
using mozilla::DebugOnly;
using mozilla::Maybe;
struct ModuleEnvironment;
// The Opcode compactly and safely represents the primary opcode plus any
// extension, with convenient predicates and accessors.
class Opcode {
uint32_t bits_;
public:
MOZ_IMPLICIT Opcode(Op op) : bits_(uint32_t(op)) {
static_assert(size_t(Op::Limit) == 256, "fits");
MOZ_ASSERT(size_t(op) < size_t(Op::Limit));
}
MOZ_IMPLICIT Opcode(MiscOp op)
: bits_((uint32_t(op) << 8) | uint32_t(Op::MiscPrefix)) {
static_assert(size_t(MiscOp::Limit) <= 0xFFFFFF, "fits");
MOZ_ASSERT(size_t(op) < size_t(MiscOp::Limit));
}
MOZ_IMPLICIT Opcode(ThreadOp op)
: bits_((uint32_t(op) << 8) | uint32_t(Op::ThreadPrefix)) {
static_assert(size_t(ThreadOp::Limit) <= 0xFFFFFF, "fits");
MOZ_ASSERT(size_t(op) < size_t(ThreadOp::Limit));
}
MOZ_IMPLICIT Opcode(MozOp op)
: bits_((uint32_t(op) << 8) | uint32_t(Op::MozPrefix)) {
static_assert(size_t(MozOp::Limit) <= 0xFFFFFF, "fits");
MOZ_ASSERT(size_t(op) < size_t(MozOp::Limit));
}
MOZ_IMPLICIT Opcode(SimdOp op)
: bits_((uint32_t(op) << 8) | uint32_t(Op::SimdPrefix)) {
static_assert(size_t(SimdOp::Limit) <= 0xFFFFFF, "fits");
MOZ_ASSERT(size_t(op) < size_t(SimdOp::Limit));
}
bool isOp() const { return bits_ < uint32_t(Op::FirstPrefix); }
bool isMisc() const { return (bits_ & 255) == uint32_t(Op::MiscPrefix); }
bool isThread() const { return (bits_ & 255) == uint32_t(Op::ThreadPrefix); }
bool isMoz() const { return (bits_ & 255) == uint32_t(Op::MozPrefix); }
bool isSimd() const { return (bits_ & 255) == uint32_t(Op::SimdPrefix); }
Op asOp() const {
MOZ_ASSERT(isOp());
return Op(bits_);
}
MiscOp asMisc() const {
MOZ_ASSERT(isMisc());
return MiscOp(bits_ >> 8);
}
ThreadOp asThread() const {
MOZ_ASSERT(isThread());
return ThreadOp(bits_ >> 8);
}
MozOp asMoz() const {
MOZ_ASSERT(isMoz());
return MozOp(bits_ >> 8);
}
SimdOp asSimd() const {
MOZ_ASSERT(isSimd());
return SimdOp(bits_ >> 8);
}
uint32_t bits() const { return bits_; }
bool operator==(const Opcode& that) const { return bits_ == that.bits_; }
bool operator!=(const Opcode& that) const { return bits_ != that.bits_; }
};
// This struct captures the bytecode offset of a section's payload (so not
// including the header) and the size of the payload.
struct SectionRange {
uint32_t start;
uint32_t size;
uint32_t end() const { return start + size; }
bool operator==(const SectionRange& rhs) const {
return start == rhs.start && size == rhs.size;
}
};
using MaybeSectionRange = Maybe<SectionRange>;
// The Encoder class appends bytes to the Bytes object it is given during
// construction. The client is responsible for the Bytes's lifetime and must
// keep the Bytes alive as long as the Encoder is used.
class Encoder {
Bytes& bytes_;
template <class T>
[[nodiscard]] bool write(const T& v) {
return bytes_.append(reinterpret_cast<const uint8_t*>(&v), sizeof(T));
}
template <typename UInt>
[[nodiscard]] bool writeVarU(UInt i) {
do {
uint8_t byte = i & 0x7f;
i >>= 7;
if (i != 0) {
byte |= 0x80;
}
if (!bytes_.append(byte)) {
return false;
}
} while (i != 0);
return true;
}
template <typename SInt>
[[nodiscard]] bool writeVarS(SInt i) {
bool done;
do {
uint8_t byte = i & 0x7f;
i >>= 7;
done = ((i == 0) && !(byte & 0x40)) || ((i == -1) && (byte & 0x40));
if (!done) {
byte |= 0x80;
}
if (!bytes_.append(byte)) {
return false;
}
} while (!done);
return true;
}
void patchVarU32(size_t offset, uint32_t patchBits, uint32_t assertBits) {
do {
uint8_t assertByte = assertBits & 0x7f;
uint8_t patchByte = patchBits & 0x7f;
assertBits >>= 7;
patchBits >>= 7;
if (assertBits != 0) {
assertByte |= 0x80;
patchByte |= 0x80;
}
MOZ_ASSERT(assertByte == bytes_[offset]);
(void)assertByte;
bytes_[offset] = patchByte;
offset++;
} while (assertBits != 0);
}
void patchFixedU7(size_t offset, uint8_t patchBits, uint8_t assertBits) {
MOZ_ASSERT(patchBits <= uint8_t(INT8_MAX));
patchFixedU8(offset, patchBits, assertBits);
}
void patchFixedU8(size_t offset, uint8_t patchBits, uint8_t assertBits) {
MOZ_ASSERT(bytes_[offset] == assertBits);
bytes_[offset] = patchBits;
}
uint32_t varU32ByteLength(size_t offset) const {
size_t start = offset;
while (bytes_[offset] & 0x80) {
offset++;
}
return offset - start + 1;
}
public:
explicit Encoder(Bytes& bytes) : bytes_(bytes) { MOZ_ASSERT(empty()); }
size_t currentOffset() const { return bytes_.length(); }
bool empty() const { return currentOffset() == 0; }
// Fixed-size encoding operations simply copy the literal bytes (without
// attempting to align).
[[nodiscard]] bool writeFixedU7(uint8_t i) {
MOZ_ASSERT(i <= uint8_t(INT8_MAX));
return writeFixedU8(i);
}
[[nodiscard]] bool writeFixedU8(uint8_t i) { return write<uint8_t>(i); }
[[nodiscard]] bool writeFixedU32(uint32_t i) { return write<uint32_t>(i); }
[[nodiscard]] bool writeFixedF32(float f) { return write<float>(f); }
[[nodiscard]] bool writeFixedF64(double d) { return write<double>(d); }
// Variable-length encodings that all use LEB128.
[[nodiscard]] bool writeVarU32(uint32_t i) { return writeVarU<uint32_t>(i); }
[[nodiscard]] bool writeVarS32(int32_t i) { return writeVarS<int32_t>(i); }
[[nodiscard]] bool writeVarU64(uint64_t i) { return writeVarU<uint64_t>(i); }
[[nodiscard]] bool writeVarS64(int64_t i) { return writeVarS<int64_t>(i); }
[[nodiscard]] bool writeValType(ValType type) {
static_assert(size_t(TypeCode::Limit) <= UINT8_MAX, "fits");
if (type.isTypeIndex()) {
return writeFixedU8(uint8_t(TypeCode::NullableRef)) &&
writeVarU32(type.refType().typeIndex());
}
TypeCode tc = type.packed().typeCode();
MOZ_ASSERT(size_t(tc) < size_t(TypeCode::Limit));
return writeFixedU8(uint8_t(tc));
}
[[nodiscard]] bool writeOp(Opcode opcode) {
// The Opcode constructor has asserted that `opcode` is meaningful, so no
// further correctness checking is necessary here.
uint32_t bits = opcode.bits();
if (!writeFixedU8(bits & 255)) {
return false;
}
if (opcode.isOp()) {
return true;
}
return writeVarU32(bits >> 8);
}
// Fixed-length encodings that allow back-patching.
[[nodiscard]] bool writePatchableFixedU7(size_t* offset) {
*offset = bytes_.length();
return writeFixedU8(UINT8_MAX);
}
void patchFixedU7(size_t offset, uint8_t patchBits) {
return patchFixedU7(offset, patchBits, UINT8_MAX);
}
// Variable-length encodings that allow back-patching.
[[nodiscard]] bool writePatchableVarU32(size_t* offset) {
*offset = bytes_.length();
return writeVarU32(UINT32_MAX);
}
void patchVarU32(size_t offset, uint32_t patchBits) {
return patchVarU32(offset, patchBits, UINT32_MAX);
}
// Byte ranges start with an LEB128 length followed by an arbitrary sequence
// of bytes. When used for strings, bytes are to be interpreted as utf8.
[[nodiscard]] bool writeBytes(const void* bytes, uint32_t numBytes) {
return writeVarU32(numBytes) &&
bytes_.append(reinterpret_cast<const uint8_t*>(bytes), numBytes);
}
// A "section" is a contiguous range of bytes that stores its own size so
// that it may be trivially skipped without examining the payload. Sections
// require backpatching since the size of the section is only known at the
// end while the size's varU32 must be stored at the beginning. Immediately
// after the section length is the string id of the section.
[[nodiscard]] bool startSection(SectionId id, size_t* offset) {
MOZ_ASSERT(uint32_t(id) < 128);
return writeVarU32(uint32_t(id)) && writePatchableVarU32(offset);
}
void finishSection(size_t offset) {
return patchVarU32(offset,
bytes_.length() - offset - varU32ByteLength(offset));
}
};
// The Decoder class decodes the bytes in the range it is given during
// construction. The client is responsible for keeping the byte range alive as
// long as the Decoder is used.
class Decoder {
const uint8_t* const beg_;
const uint8_t* const end_;
const uint8_t* cur_;
const size_t offsetInModule_;
UniqueChars* error_;
UniqueCharsVector* warnings_;
bool resilientMode_;
template <class T>
[[nodiscard]] bool read(T* out) {
if (bytesRemain() < sizeof(T)) {
return false;
}
memcpy((void*)out, cur_, sizeof(T));
cur_ += sizeof(T);
return true;
}
template <class T>
T uncheckedRead() {
MOZ_ASSERT(bytesRemain() >= sizeof(T));
T ret;
memcpy(&ret, cur_, sizeof(T));
cur_ += sizeof(T);
return ret;
}
template <class T>
void uncheckedRead(T* ret) {
MOZ_ASSERT(bytesRemain() >= sizeof(T));
memcpy(ret, cur_, sizeof(T));
cur_ += sizeof(T);
}
template <typename UInt>
[[nodiscard]] bool readVarU(UInt* out) {
DebugOnly<const uint8_t*> before = cur_;
const unsigned numBits = sizeof(UInt) * CHAR_BIT;
const unsigned remainderBits = numBits % 7;
const unsigned numBitsInSevens = numBits - remainderBits;
UInt u = 0;
uint8_t byte;
UInt shift = 0;
do {
if (!readFixedU8(&byte)) {
return false;
}
if (!(byte & 0x80)) {
*out = u | UInt(byte) << shift;
return true;
}
u |= UInt(byte & 0x7F) << shift;
shift += 7;
} while (shift != numBitsInSevens);
if (!readFixedU8(&byte) || (byte & (unsigned(-1) << remainderBits))) {
return false;
}
*out = u | (UInt(byte) << numBitsInSevens);
MOZ_ASSERT_IF(sizeof(UInt) == 4,
unsigned(cur_ - before) <= MaxVarU32DecodedBytes);
return true;
}
template <typename SInt>
[[nodiscard]] bool readVarS(SInt* out) {
using UInt = std::make_unsigned_t<SInt>;
const unsigned numBits = sizeof(SInt) * CHAR_BIT;
const unsigned remainderBits = numBits % 7;
const unsigned numBitsInSevens = numBits - remainderBits;
SInt s = 0;
uint8_t byte;
unsigned shift = 0;
do {
if (!readFixedU8(&byte)) {
return false;
}
s |= SInt(byte & 0x7f) << shift;
shift += 7;
if (!(byte & 0x80)) {
if (byte & 0x40) {
s |= UInt(-1) << shift;
}
*out = s;
return true;
}
} while (shift < numBitsInSevens);
if (!remainderBits || !readFixedU8(&byte) || (byte & 0x80)) {
return false;
}
uint8_t mask = 0x7f & (uint8_t(-1) << remainderBits);
if ((byte & mask) != ((byte & (1 << (remainderBits - 1))) ? mask : 0)) {
return false;
}
*out = s | UInt(byte) << shift;
return true;
}
public:
Decoder(const uint8_t* begin, const uint8_t* end, size_t offsetInModule,
UniqueChars* error, UniqueCharsVector* warnings = nullptr,
bool resilientMode = false)
: beg_(begin),
end_(end),
cur_(begin),
offsetInModule_(offsetInModule),
error_(error),
warnings_(warnings),
resilientMode_(resilientMode) {
MOZ_ASSERT(begin <= end);
}
explicit Decoder(const Bytes& bytes, size_t offsetInModule = 0,
UniqueChars* error = nullptr,
UniqueCharsVector* warnings = nullptr)
: beg_(bytes.begin()),
end_(bytes.end()),
cur_(bytes.begin()),
offsetInModule_(offsetInModule),
error_(error),
warnings_(warnings),
resilientMode_(false) {}
// These convenience functions use currentOffset() as the errorOffset.
bool fail(const char* msg) { return fail(currentOffset(), msg); }
bool failf(const char* msg, ...) MOZ_FORMAT_PRINTF(2, 3);
void warnf(const char* msg, ...) MOZ_FORMAT_PRINTF(2, 3);
// Report an error at the given offset (relative to the whole module).
bool fail(size_t errorOffset, const char* msg);
UniqueChars* error() { return error_; }
void clearError() {
if (error_) {
error_->reset();
}
}
bool done() const {
MOZ_ASSERT(cur_ <= end_);
return cur_ == end_;
}
bool resilientMode() const { return resilientMode_; }
size_t bytesRemain() const {
MOZ_ASSERT(end_ >= cur_);
return size_t(end_ - cur_);
}
// pos must be a value previously returned from currentPosition.
void rollbackPosition(const uint8_t* pos) { cur_ = pos; }
const uint8_t* currentPosition() const { return cur_; }
size_t beginOffset() const { return offsetInModule_; }
size_t currentOffset() const { return offsetInModule_ + (cur_ - beg_); }
const uint8_t* begin() const { return beg_; }
const uint8_t* end() const { return end_; }
// Peek at the next byte, if it exists, without advancing the position.
bool peekByte(uint8_t* byte) {
if (done()) {
return false;
}
*byte = *cur_;
return true;
}
// Fixed-size encoding operations simply copy the literal bytes (without
// attempting to align).
[[nodiscard]] bool readFixedU8(uint8_t* i) { return read<uint8_t>(i); }
[[nodiscard]] bool readFixedU32(uint32_t* u) { return read<uint32_t>(u); }
[[nodiscard]] bool readFixedF32(float* f) { return read<float>(f); }
[[nodiscard]] bool readFixedF64(double* d) { return read<double>(d); }
#ifdef ENABLE_WASM_SIMD
[[nodiscard]] bool readFixedV128(V128* d) {
for (unsigned i = 0; i < 16; i++) {
if (!read<uint8_t>(d->bytes + i)) {
return false;
}
}
return true;
}
#endif
// Variable-length encodings that all use LEB128.
[[nodiscard]] bool readVarU32(uint32_t* out) {
return readVarU<uint32_t>(out);
}
[[nodiscard]] bool readVarS32(int32_t* out) { return readVarS<int32_t>(out); }
[[nodiscard]] bool readVarU64(uint64_t* out) {
return readVarU<uint64_t>(out);
}
[[nodiscard]] bool readVarS64(int64_t* out) { return readVarS<int64_t>(out); }
// Value and reference types
[[nodiscard]] ValType uncheckedReadValType();
template <class T>
[[nodiscard]] bool readPackedType(uint32_t numTypes,
const FeatureArgs& features, T* type);
template <class T>
[[nodiscard]] bool readPackedType(const TypeContext& types,
const FeatureArgs& features, T* type);
[[nodiscard]] bool readValType(uint32_t numTypes, const FeatureArgs& features,
ValType* type);
[[nodiscard]] bool readValType(const TypeContext& types,
const FeatureArgs& features, ValType* type);
[[nodiscard]] bool readFieldType(uint32_t numTypes,
const FeatureArgs& features,
FieldType* type);
[[nodiscard]] bool readFieldType(const TypeContext& types,
const FeatureArgs& features,
FieldType* type);
[[nodiscard]] bool readHeapType(uint32_t numTypes,
const FeatureArgs& features, bool nullable,
RefType* type);
[[nodiscard]] bool readHeapType(const TypeContext& types,
const FeatureArgs& features, bool nullable,
RefType* type);
[[nodiscard]] bool readRefType(uint32_t numTypes, const FeatureArgs& features,
RefType* type);
[[nodiscard]] bool readRefType(const TypeContext& types,
const FeatureArgs& features, RefType* type);
[[nodiscard]] bool validateTypeIndex(const TypeContext& types,
const FeatureArgs& features,
RefType type);
// Instruction opcode
[[nodiscard]] bool readOp(OpBytes* op);
// Instruction immediates for constant instructions
[[nodiscard]] bool readBinary() { return true; }
[[nodiscard]] bool readTypeIndex(uint32_t* typeIndex);
[[nodiscard]] bool readGlobalIndex(uint32_t* globalIndex);
[[nodiscard]] bool readFuncIndex(uint32_t* funcIndex);
[[nodiscard]] bool readI32Const(int32_t* i32);
[[nodiscard]] bool readI64Const(int64_t* i64);
[[nodiscard]] bool readF32Const(float* f32);
[[nodiscard]] bool readF64Const(double* f64);
#ifdef ENABLE_WASM_SIMD
[[nodiscard]] bool readV128Const(V128* value);
#endif
[[nodiscard]] bool readRefNull(const TypeContext& types,
const FeatureArgs& features, RefType* type);
[[nodiscard]] bool readRefNull(const FeatureArgs& features, RefType* type);
// See writeBytes comment.
[[nodiscard]] bool readBytes(uint32_t numBytes,
const uint8_t** bytes = nullptr) {
if (bytes) {
*bytes = cur_;
}
if (bytesRemain() < numBytes) {
return false;
}
cur_ += numBytes;
return true;
}
// See "section" description in Encoder.
[[nodiscard]] bool readSectionHeader(uint8_t* id, SectionRange* range);
[[nodiscard]] bool startSection(SectionId id, ModuleEnvironment* env,
MaybeSectionRange* range,
const char* sectionName);
[[nodiscard]] bool finishSection(const SectionRange& range,
const char* sectionName);
// Custom sections do not cause validation errors unless the error is in
// the section header itself.
[[nodiscard]] bool startCustomSection(const char* expected,
size_t expectedLength,
ModuleEnvironment* env,
MaybeSectionRange* range);
template <size_t NameSizeWith0>
[[nodiscard]] bool startCustomSection(const char (&name)[NameSizeWith0],
ModuleEnvironment* env,
MaybeSectionRange* range) {
MOZ_ASSERT(name[NameSizeWith0 - 1] == '\0');
return startCustomSection(name, NameSizeWith0 - 1, env, range);
}
void finishCustomSection(const char* name, const SectionRange& range);
void skipAndFinishCustomSection(const SectionRange& range);
[[nodiscard]] bool skipCustomSection(ModuleEnvironment* env);
// The Name section has its own optional subsections.
[[nodiscard]] bool startNameSubsection(NameType nameType,
Maybe<uint32_t>* endOffset);
[[nodiscard]] bool finishNameSubsection(uint32_t endOffset);
[[nodiscard]] bool skipNameSubsection();
// The infallible "unchecked" decoding functions can be used when we are
// sure that the bytes are well-formed (by construction or due to previous
// validation).
uint8_t uncheckedReadFixedU8() { return uncheckedRead<uint8_t>(); }
uint32_t uncheckedReadFixedU32() { return uncheckedRead<uint32_t>(); }
void uncheckedReadFixedF32(float* out) { uncheckedRead<float>(out); }
void uncheckedReadFixedF64(double* out) { uncheckedRead<double>(out); }
template <typename UInt>
UInt uncheckedReadVarU() {
static const unsigned numBits = sizeof(UInt) * CHAR_BIT;
static const unsigned remainderBits = numBits % 7;
static const unsigned numBitsInSevens = numBits - remainderBits;
UInt decoded = 0;
uint32_t shift = 0;
do {
uint8_t byte = *cur_++;
if (!(byte & 0x80)) {
return decoded | (UInt(byte) << shift);
}
decoded |= UInt(byte & 0x7f) << shift;
shift += 7;
} while (shift != numBitsInSevens);
uint8_t byte = *cur_++;
MOZ_ASSERT(!(byte & 0xf0));
return decoded | (UInt(byte) << numBitsInSevens);
}
uint32_t uncheckedReadVarU32() { return uncheckedReadVarU<uint32_t>(); }
int32_t uncheckedReadVarS32() {
int32_t i32 = 0;
MOZ_ALWAYS_TRUE(readVarS32(&i32));
return i32;
}
uint64_t uncheckedReadVarU64() { return uncheckedReadVarU<uint64_t>(); }
int64_t uncheckedReadVarS64() {
int64_t i64 = 0;
MOZ_ALWAYS_TRUE(readVarS64(&i64));
return i64;
}
Op uncheckedReadOp() {
static_assert(size_t(Op::Limit) == 256, "fits");
uint8_t u8 = uncheckedReadFixedU8();
return u8 != UINT8_MAX ? Op(u8) : Op(uncheckedReadFixedU8() + UINT8_MAX);
}
};
// Value and reference types
inline ValType Decoder::uncheckedReadValType() {
uint8_t code = uncheckedReadFixedU8();
switch (code) {
case uint8_t(TypeCode::FuncRef):
case uint8_t(TypeCode::ExternRef):
return RefType::fromTypeCode(TypeCode(code), true);
case uint8_t(TypeCode::RttWithDepth): {
uint32_t rttDepth = uncheckedReadVarU32();
int32_t typeIndex = uncheckedReadVarS32();
return ValType::fromRtt(typeIndex, rttDepth);
}
case uint8_t(TypeCode::Rtt): {
int32_t typeIndex = uncheckedReadVarS32();
return ValType::fromRtt(typeIndex, RttDepthNone);
}
case uint8_t(TypeCode::Ref):
case uint8_t(TypeCode::NullableRef): {
bool nullable = code == uint8_t(TypeCode::NullableRef);
uint8_t nextByte;
peekByte(&nextByte);
if ((nextByte & SLEB128SignMask) == SLEB128SignBit) {
uint8_t code = uncheckedReadFixedU8();
return RefType::fromTypeCode(TypeCode(code), nullable);
}
int32_t x = uncheckedReadVarS32();
return RefType::fromTypeIndex(x, nullable);
}
default:
return ValType::fromNonRefTypeCode(TypeCode(code));
}
}
template <class T>
inline bool Decoder::readPackedType(uint32_t numTypes,
const FeatureArgs& features, T* type) {
static_assert(uint8_t(TypeCode::Limit) <= UINT8_MAX, "fits");
uint8_t code;
if (!readFixedU8(&code)) {
return fail("expected type code");
}
switch (code) {
case uint8_t(TypeCode::V128): {
#ifdef ENABLE_WASM_SIMD
if (!features.v128) {
return fail("v128 not enabled");
}
*type = T::fromNonRefTypeCode(TypeCode(code));
return true;
#else
break;
#endif
}
case uint8_t(TypeCode::FuncRef):
case uint8_t(TypeCode::ExternRef): {
*type = RefType::fromTypeCode(TypeCode(code), true);
return true;
}
case uint8_t(TypeCode::Ref):
case uint8_t(TypeCode::NullableRef): {
#ifdef ENABLE_WASM_FUNCTION_REFERENCES
if (!features.functionReferences) {
return fail("(ref T) types not enabled");
}
bool nullable = code == uint8_t(TypeCode::NullableRef);
RefType refType;
if (!readHeapType(numTypes, features, nullable, &refType)) {
return false;
}
*type = refType;
return true;
#else
break;
#endif
}
case uint8_t(TypeCode::Rtt):
case uint8_t(TypeCode::RttWithDepth): {
#ifdef ENABLE_WASM_GC
if (!features.gc) {
return fail("gc types not enabled");
}
uint32_t rttDepth = RttDepthNone;
if (code == uint8_t(TypeCode::RttWithDepth) &&
(!readVarU32(&rttDepth) || uint32_t(rttDepth) >= MaxRttDepth)) {
return fail("invalid rtt depth");
}
RefType heapType;
if (!readHeapType(numTypes, features, true, &heapType)) {
return false;
}
if (!heapType.isTypeIndex()) {
return fail("invalid heap type for rtt");
}
*type = T::fromRtt(heapType.typeIndex(), rttDepth);
return true;
#else
break;
#endif
}
case uint8_t(TypeCode::EqRef): {
#ifdef ENABLE_WASM_GC
if (!features.gc) {
return fail("gc types not enabled");
}
*type = RefType::fromTypeCode(TypeCode(code), true);
return true;
#else
break;
#endif
}
default: {
if (!T::isValidTypeCode(TypeCode(code))) {
break;
}
*type = T::fromNonRefTypeCode(TypeCode(code));
return true;
}
}
return fail("bad type");
}
template <class T>
inline bool Decoder::readPackedType(const TypeContext& types,
const FeatureArgs& features, T* type) {
if (!readPackedType(types.length(), features, type)) {
return false;
}
if (type->isTypeIndex() &&
!validateTypeIndex(types, features, type->refType())) {
return false;
}
return true;
}
inline bool Decoder::readValType(uint32_t numTypes, const FeatureArgs& features,
ValType* type) {
return readPackedType<ValType>(numTypes, features, type);
}
inline bool Decoder::readValType(const TypeContext& types,
const FeatureArgs& features, ValType* type) {
return readPackedType<ValType>(types, features, type);
}
inline bool Decoder::readFieldType(uint32_t numTypes,
const FeatureArgs& features,
FieldType* type) {
return readPackedType<FieldType>(numTypes, features, type);
}
inline bool Decoder::readFieldType(const TypeContext& types,
const FeatureArgs& features,
FieldType* type) {
return readPackedType<FieldType>(types, features, type);
}
inline bool Decoder::readHeapType(uint32_t numTypes,
const FeatureArgs& features, bool nullable,
RefType* type) {
uint8_t nextByte;
if (!peekByte(&nextByte)) {
return fail("expected heap type code");
}
if ((nextByte & SLEB128SignMask) == SLEB128SignBit) {
uint8_t code;
if (!readFixedU8(&code)) {
return false;
}
switch (code) {
case uint8_t(TypeCode::FuncRef):
case uint8_t(TypeCode::ExternRef):
*type = RefType::fromTypeCode(TypeCode(code), nullable);
return true;
#ifdef ENABLE_WASM_GC
case uint8_t(TypeCode::EqRef):
if (!features.gc) {
return fail("gc types not enabled");
}
*type = RefType::fromTypeCode(TypeCode(code), nullable);
return true;
#endif
default:
return fail("invalid heap type");
}
}
#ifdef ENABLE_WASM_FUNCTION_REFERENCES
if (features.functionReferences) {
int32_t x;
if (!readVarS32(&x) || x < 0 || uint32_t(x) >= numTypes ||
uint32_t(x) >= MaxTypeIndex) {
return fail("invalid heap type index");
}
*type = RefType::fromTypeIndex(x, nullable);
return true;
}
#endif
return fail("invalid heap type");
}
inline bool Decoder::readHeapType(const TypeContext& types,
const FeatureArgs& features, bool nullable,
RefType* type) {
if (!readHeapType(types.length(), features, nullable, type)) {
return false;
}
if (type->isTypeIndex() && !validateTypeIndex(types, features, *type)) {
return false;
}
return true;
}
inline bool Decoder::readRefType(uint32_t numTypes, const FeatureArgs& features,
RefType* type) {
ValType valType;
if (!readValType(numTypes, features, &valType)) {
return false;
}
if (!valType.isRefType()) {
return fail("bad type");
}
*type = valType.refType();
return true;
}
inline bool Decoder::readRefType(const TypeContext& types,
const FeatureArgs& features, RefType* type) {
ValType valType;
if (!readValType(types, features, &valType)) {
return false;
}
if (!valType.isRefType()) {
return fail("bad type");
}
*type = valType.refType();
return true;
}
inline bool Decoder::validateTypeIndex(const TypeContext& types,
const FeatureArgs& features,
RefType type) {
MOZ_ASSERT(type.isTypeIndex());
if (features.gc && (types[type.typeIndex()].isStructType() ||
types[type.typeIndex()].isArrayType())) {
return true;
}
return fail("type index references an invalid type");
}
// Instruction opcode
inline bool Decoder::readOp(OpBytes* op) {
static_assert(size_t(Op::Limit) == 256, "fits");
uint8_t u8;
if (!readFixedU8(&u8)) {
return false;
}
op->b0 = u8;
if (MOZ_LIKELY(!IsPrefixByte(u8))) {
return true;
}
return readVarU32(&op->b1);
}
// Instruction immediates for constant instructions
inline bool Decoder::readTypeIndex(uint32_t* typeIndex) {
if (!readVarU32(typeIndex)) {
return fail("unable to read type index");
}
return true;
}
inline bool Decoder::readGlobalIndex(uint32_t* globalIndex) {
if (!readVarU32(globalIndex)) {
return fail("unable to read global index");
}
return true;
}
inline bool Decoder::readFuncIndex(uint32_t* funcIndex) {
if (!readVarU32(funcIndex)) {
return fail("unable to read function index");
}
return true;
}
inline bool Decoder::readI32Const(int32_t* i32) {
if (!readVarS32(i32)) {
return fail("failed to read I32 constant");
}
return true;
}
inline bool Decoder::readI64Const(int64_t* i64) {
if (!readVarS64(i64)) {
return fail("failed to read I64 constant");
}
return true;
}
inline bool Decoder::readF32Const(float* f32) {
if (!readFixedF32(f32)) {
return fail("failed to read F32 constant");
}
return true;
}
inline bool Decoder::readF64Const(double* f64) {
if (!readFixedF64(f64)) {
return fail("failed to read F64 constant");
}
return true;
}
#ifdef ENABLE_WASM_SIMD
inline bool Decoder::readV128Const(V128* value) {
if (!readFixedV128(value)) {
return fail("unable to read V128 constant");
}
return true;
}
#endif
inline bool Decoder::readRefNull(const TypeContext& types,
const FeatureArgs& features, RefType* type) {
return readHeapType(types, features, true, type);
}
inline bool Decoder::readRefNull(const FeatureArgs& features, RefType* type) {
return readHeapType(MaxTypes, features, true, type);
}
} // namespace wasm
} // namespace js
#endif // namespace wasm_binary_h