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 20 namespace v8 { 21 namespace internal { 22 namespace 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. 29 class CWasmArgumentsPacker { 30 public: CWasmArgumentsPacker(size_t buffer_size)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()) {} argv()35 i::Address argv() const { return reinterpret_cast<i::Address>(buffer_); } Reset()36 void Reset() { offset_ = 0; } 37 38 template <typename T> Push(T val)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> Pop()46 T Pop() { 47 Address address = reinterpret_cast<Address>(buffer_ + offset_); 48 offset_ += sizeof(T); 49 return base::ReadUnalignedValue<T>(address); 50 } 51 TotalSize(const FunctionSig * sig)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