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// Copyright 2015 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_FUNCTION_BODY_DECODER_H_
#define V8_WASM_FUNCTION_BODY_DECODER_H_
#include "src/base/compiler-specific.h"
#include "src/base/iterator.h"
#include "src/common/globals.h"
#include "src/wasm/decoder.h"
#include "src/wasm/wasm-opcodes.h"
#include "src/wasm/wasm-result.h"
#include "src/zone/zone-containers.h"
namespace v8::internal {
class AccountingAllocator;
class BitVector;
} // namespace v8::internal
namespace v8::internal::wasm {
class WasmFeatures;
struct WasmModule; // forward declaration of module interface.
// A wrapper around the signature and bytes of a function.
struct FunctionBody {
const FunctionSig* sig; // function signature
uint32_t offset; // offset in the module bytes, for error reporting
const uint8_t* start; // start of the function body
const uint8_t* end; // end of the function body
FunctionBody(const FunctionSig* sig, uint32_t offset, const uint8_t* start,
const uint8_t* end)
: sig(sig), offset(offset), start(start), end(end) {}
};
enum class LoadTransformationKind : uint8_t { kSplat, kExtend, kZeroExtend };
V8_EXPORT_PRIVATE DecodeResult ValidateFunctionBody(const WasmFeatures& enabled,
const WasmModule* module,
WasmFeatures* detected,
const FunctionBody& body);
enum PrintLocals { kPrintLocals, kOmitLocals };
V8_EXPORT_PRIVATE
bool PrintRawWasmCode(AccountingAllocator* allocator, const FunctionBody& body,
const WasmModule* module, PrintLocals print_locals);
V8_EXPORT_PRIVATE
bool PrintRawWasmCode(AccountingAllocator* allocator, const FunctionBody& body,
const WasmModule* module, PrintLocals print_locals,
std::ostream& out,
std::vector<int>* line_numbers = nullptr);
// A simplified form of AST printing, e.g. from a debugger.
void PrintRawWasmCode(const uint8_t* start, const uint8_t* end);
struct BodyLocalDecls {
// The size of the encoded declarations.
uint32_t encoded_size = 0; // size of encoded declarations
uint32_t num_locals = 0;
ValueType* local_types = nullptr;
};
// Decode locals; validation is not performed.
V8_EXPORT_PRIVATE void DecodeLocalDecls(WasmFeatures enabled,
BodyLocalDecls* decls,
const uint8_t* start,
const uint8_t* end, Zone* zone);
// Decode locals, including validation.
V8_EXPORT_PRIVATE bool ValidateAndDecodeLocalDeclsForTesting(
WasmFeatures enabled, BodyLocalDecls* decls, const WasmModule* module,
const uint8_t* start, const uint8_t* end, Zone* zone);
V8_EXPORT_PRIVATE BitVector* AnalyzeLoopAssignmentForTesting(
Zone* zone, uint32_t num_locals, const uint8_t* start, const uint8_t* end,
bool* loop_is_innermost);
// Computes the length of the opcode at the given address.
V8_EXPORT_PRIVATE unsigned OpcodeLength(const uint8_t* pc, const uint8_t* end);
// Checks if the underlying hardware supports the Wasm SIMD proposal.
V8_EXPORT_PRIVATE bool CheckHardwareSupportsSimd();
// A simple forward iterator for bytecodes.
class V8_EXPORT_PRIVATE BytecodeIterator : public NON_EXPORTED_BASE(Decoder) {
// Base class for both iterators defined below.
class iterator_base {
public:
iterator_base& operator++() {
DCHECK_LT(ptr_, end_);
ptr_ += OpcodeLength(ptr_, end_);
return *this;
}
bool operator==(const iterator_base& that) const {
return this->ptr_ == that.ptr_;
}
bool operator!=(const iterator_base& that) const {
return this->ptr_ != that.ptr_;
}
protected:
const uint8_t* ptr_;
const uint8_t* end_;
iterator_base(const uint8_t* ptr, const uint8_t* end)
: ptr_(ptr), end_(end) {}
};
public:
// If one wants to iterate over the bytecode without looking at {pc_offset()}.
class opcode_iterator
: public iterator_base,
public base::iterator<std::input_iterator_tag, WasmOpcode> {
public:
WasmOpcode operator*() {
DCHECK_LT(ptr_, end_);
return static_cast<WasmOpcode>(*ptr_);
}
private:
friend class BytecodeIterator;
opcode_iterator(const uint8_t* ptr, const uint8_t* end)
: iterator_base(ptr, end) {}
};
// If one wants to iterate over the instruction offsets without looking at
// opcodes.
class offset_iterator
: public iterator_base,
public base::iterator<std::input_iterator_tag, uint32_t> {
public:
uint32_t operator*() {
DCHECK_LT(ptr_, end_);
return static_cast<uint32_t>(ptr_ - start_);
}
private:
const uint8_t* start_;
friend class BytecodeIterator;
offset_iterator(const uint8_t* start, const uint8_t* ptr,
const uint8_t* end)
: iterator_base(ptr, end), start_(start) {}
};
// Create a new {BytecodeIterator}, starting after the locals declarations.
BytecodeIterator(const uint8_t* start, const uint8_t* end);
// Create a new {BytecodeIterator}, starting with locals declarations.
BytecodeIterator(const uint8_t* start, const uint8_t* end,
BodyLocalDecls* decls, Zone* zone);
base::iterator_range<opcode_iterator> opcodes() const {
return base::iterator_range<opcode_iterator>(opcode_iterator(pc_, end_),
opcode_iterator(end_, end_));
}
base::iterator_range<offset_iterator> offsets() const {
return base::iterator_range<offset_iterator>(
offset_iterator(start_, pc_, end_),
offset_iterator(start_, end_, end_));
}
WasmOpcode current() {
return static_cast<WasmOpcode>(
read_u8<Decoder::NoValidationTag>(pc_, "expected bytecode"));
}
void next() {
if (pc_ < end_) {
pc_ += OpcodeLength(pc_, end_);
if (pc_ >= end_) pc_ = end_;
}
}
bool has_next() const { return pc_ < end_; }
WasmOpcode prefixed_opcode() {
auto [opcode, length] = read_prefixed_opcode<Decoder::NoValidationTag>(pc_);
return opcode;
}
const uint8_t* pc() const { return pc_; }
};
} // namespace v8::internal::wasm
#endif // V8_WASM_FUNCTION_BODY_DECODER_H_
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