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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.
#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"
namespace v8 {
namespace internal {
class BitVector; // forward declaration
namespace wasm {
struct WasmModule; // forward declaration of module interface.
struct WasmFeatures;
// A wrapper around the signature and bytes of a function.
struct FunctionBody {
FunctionSig* sig; // function signature
uint32_t offset; // offset in the module bytes, for error reporting
const byte* start; // start of the function body
const byte* end; // end of the function body
FunctionBody(FunctionSig* sig, uint32_t offset, const byte* start,
const byte* end)
: sig(sig), offset(offset), start(start), end(end) {}
};
V8_EXPORT_PRIVATE DecodeResult VerifyWasmCode(AccountingAllocator* allocator,
const WasmFeatures& enabled,
const WasmModule* module,
WasmFeatures* detected,
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 byte* start, const byte* end);
struct BodyLocalDecls {
// The size of the encoded declarations.
uint32_t encoded_size = 0; // size of encoded declarations
ZoneVector<ValueType> type_list;
explicit BodyLocalDecls(Zone* zone) : type_list(zone) {}
};
V8_EXPORT_PRIVATE bool DecodeLocalDecls(const WasmFeatures& enabled,
BodyLocalDecls* decls,
const byte* start, const byte* end);
V8_EXPORT_PRIVATE BitVector* AnalyzeLoopAssignmentForTesting(Zone* zone,
size_t num_locals,
const byte* start,
const byte* end);
// Computes the length of the opcode at the given address.
V8_EXPORT_PRIVATE unsigned OpcodeLength(const byte* pc, const byte* end);
// Computes the stack effect of the opcode at the given address.
// Returns <pop count, push count>.
// Be cautious with control opcodes: This function only covers their immediate,
// local stack effect (e.g. BrIf pops 1, Br pops 0). Those opcodes can have
// non-local stack effect though, which are not covered here.
std::pair<uint32_t, uint32_t> StackEffect(const WasmModule* module,
FunctionSig* sig, const byte* pc,
const byte* end);
// 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:
inline iterator_base& operator++() {
DCHECK_LT(ptr_, end_);
ptr_ += OpcodeLength(ptr_, end_);
return *this;
}
inline bool operator==(const iterator_base& that) {
return this->ptr_ == that.ptr_;
}
inline bool operator!=(const iterator_base& that) {
return this->ptr_ != that.ptr_;
}
protected:
const byte* ptr_;
const byte* end_;
iterator_base(const byte* ptr, const byte* 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:
inline WasmOpcode operator*() {
DCHECK_LT(ptr_, end_);
return static_cast<WasmOpcode>(*ptr_);
}
private:
friend class BytecodeIterator;
opcode_iterator(const byte* ptr, const byte* 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:
inline uint32_t operator*() {
DCHECK_LT(ptr_, end_);
return static_cast<uint32_t>(ptr_ - start_);
}
private:
const byte* start_;
friend class BytecodeIterator;
offset_iterator(const byte* start, const byte* ptr, const byte* end)
: iterator_base(ptr, end), start_(start) {}
};
// Create a new {BytecodeIterator}. If the {decls} pointer is non-null,
// assume the bytecode starts with local declarations and decode them.
// Otherwise, do not decode local decls.
BytecodeIterator(const byte* start, const byte* end,
BodyLocalDecls* decls = nullptr);
base::iterator_range<opcode_iterator> opcodes() {
return base::iterator_range<opcode_iterator>(opcode_iterator(pc_, end_),
opcode_iterator(end_, end_));
}
base::iterator_range<offset_iterator> offsets() {
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::kNoValidate>(pc_, "expected bytecode"));
}
void next() {
if (pc_ < end_) {
pc_ += OpcodeLength(pc_, end_);
if (pc_ >= end_) pc_ = end_;
}
}
bool has_next() { return pc_ < end_; }
WasmOpcode prefixed_opcode() {
byte prefix = read_u8<Decoder::kNoValidate>(pc_, "expected prefix");
byte index = read_u8<Decoder::kNoValidate>(pc_ + 1, "expected index");
return static_cast<WasmOpcode>(prefix << 8 | index);
}
};
} // namespace wasm
} // namespace internal
} // namespace v8
#endif // V8_WASM_FUNCTION_BODY_DECODER_H_