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// Copyright 2019 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_WASM_ARGUMENTS_H_
#define V8_WASM_WASM_ARGUMENTS_H_
#include <stdint.h>
#include <vector>
#include "src/base/memory.h"
#include "src/codegen/signature.h"
#include "src/common/globals.h"
#include "src/wasm/value-type.h"
namespace v8 {
namespace internal {
namespace wasm {
// Helper class for {Push}ing Wasm value arguments onto the stack in the format
// that the CWasmEntryStub expects, as well as for {Pop}ping return values.
// {Reset} must be called if a packer instance used for pushing is then
// reused for popping: it resets the internal pointer to the beginning of
// the stack region.
class CWasmArgumentsPacker {
public:
explicit CWasmArgumentsPacker(size_t buffer_size)
: heap_buffer_(buffer_size <= kMaxOnStackBuffer ? 0 : buffer_size),
buffer_((buffer_size <= kMaxOnStackBuffer) ? on_stack_buffer_
: heap_buffer_.data()) {}
i::Address argv() const { return reinterpret_cast<i::Address>(buffer_); }
void Reset() { offset_ = 0; }
template <typename T>
void Push(T val) {
Address address = reinterpret_cast<Address>(buffer_ + offset_);
offset_ += sizeof(val);
base::WriteUnalignedValue(address, val);
}
template <typename T>
T Pop() {
Address address = reinterpret_cast<Address>(buffer_ + offset_);
offset_ += sizeof(T);
return base::ReadUnalignedValue<T>(address);
}
static int TotalSize(const FunctionSig* sig) {
int return_size = 0;
for (ValueType t : sig->returns()) {
return_size += t.element_size_bytes();
}
int param_size = 0;
for (ValueType t : sig->parameters()) {
param_size += t.element_size_bytes();
}
return std::max(return_size, param_size);
}
private:
static const size_t kMaxOnStackBuffer = 10 * i::kSystemPointerSize;
uint8_t on_stack_buffer_[kMaxOnStackBuffer];
std::vector<uint8_t> heap_buffer_;
uint8_t* buffer_;
size_t offset_ = 0;
};
} // namespace wasm
} // namespace internal
} // namespace v8
#endif // V8_WASM_WASM_ARGUMENTS_H_