1// Copyright 2019 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#if !V8_ENABLE_WEBASSEMBLY
6#error This header should only be included if WebAssembly is enabled.
7#endif  // !V8_ENABLE_WEBASSEMBLY
8
9#ifndef V8_WASM_WASM_ARGUMENTS_H_
10#define V8_WASM_WASM_ARGUMENTS_H_
11
12#include <stdint.h>
13#include <vector>
14
15#include "src/base/memory.h"
16#include "src/codegen/signature.h"
17#include "src/common/globals.h"
18#include "src/wasm/value-type.h"
19
20namespace v8 {
21namespace internal {
22namespace wasm {
23
24// Helper class for {Push}ing Wasm value arguments onto the stack in the format
25// that the CWasmEntryStub expects, as well as for {Pop}ping return values.
26// {Reset} must be called if a packer instance used for pushing is then
27// reused for popping: it resets the internal pointer to the beginning of
28// the stack region.
29class CWasmArgumentsPacker {
30 public:
31  explicit CWasmArgumentsPacker(size_t buffer_size)
32      : heap_buffer_(buffer_size <= kMaxOnStackBuffer ? 0 : buffer_size),
33        buffer_((buffer_size <= kMaxOnStackBuffer) ? on_stack_buffer_
34                                                   : heap_buffer_.data()) {}
35  i::Address argv() const { return reinterpret_cast<i::Address>(buffer_); }
36  void Reset() { offset_ = 0; }
37
38  template <typename T>
39  void Push(T val) {
40    Address address = reinterpret_cast<Address>(buffer_ + offset_);
41    offset_ += sizeof(val);
42    base::WriteUnalignedValue(address, val);
43  }
44
45  template <typename T>
46  T Pop() {
47    Address address = reinterpret_cast<Address>(buffer_ + offset_);
48    offset_ += sizeof(T);
49    return base::ReadUnalignedValue<T>(address);
50  }
51
52  static int TotalSize(const FunctionSig* sig) {
53    int return_size = 0;
54    for (ValueType t : sig->returns()) {
55      return_size += t.value_kind_size();
56    }
57    int param_size = 0;
58    for (ValueType t : sig->parameters()) {
59      param_size += t.value_kind_size();
60    }
61    return std::max(return_size, param_size);
62  }
63
64 private:
65  static const size_t kMaxOnStackBuffer = 10 * i::kSystemPointerSize;
66
67  uint8_t on_stack_buffer_[kMaxOnStackBuffer];
68  std::vector<uint8_t> heap_buffer_;
69  uint8_t* buffer_;
70  size_t offset_ = 0;
71};
72
73}  // namespace wasm
74}  // namespace internal
75}  // namespace v8
76
77#endif  // V8_WASM_WASM_ARGUMENTS_H_
78