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/*
* Copyright 2016 WebAssembly Community Group participants
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef wasm_support_utilities_h
#define wasm_support_utilities_h
#include "compiler-support.h"
#include <cassert>
#include <cstdint>
#include <cstring>
#include <iostream>
#include <memory>
#include <sstream>
#include <type_traits>
#include "support/bits.h"
namespace wasm {
// Type punning needs to be done through this function to avoid undefined
// behavior: unions and reinterpret_cast aren't valid approaches.
template<class Destination, class Source>
inline Destination bit_cast(const Source& source) {
static_assert(sizeof(Destination) == sizeof(Source),
"bit_cast needs to be between types of the same size");
static_assert(std::is_trivial_v<Destination> &&
std::is_standard_layout_v<Destination>,
"non-POD bit_cast undefined");
static_assert(std::is_trivial_v<Source> && std::is_standard_layout_v<Source>,
"non-POD bit_cast undefined");
Destination destination;
std::memcpy(&destination, &source, sizeof(destination));
return destination;
}
inline size_t alignAddr(size_t address, size_t alignment) {
assert(alignment && Bits::isPowerOf2((uint32_t)alignment) &&
"Alignment is not a power of two!");
assert(address + alignment - 1 >= address);
return ((address + alignment - 1) & ~(alignment - 1));
}
// For fatal errors which could arise from input (i.e. not assertion failures)
class Fatal {
private:
std::stringstream buffer;
public:
Fatal() { buffer << "Fatal: "; }
template<typename T> Fatal& operator<<(T&& arg) {
buffer << arg;
return *this;
}
#ifndef THROW_ON_FATAL
[[noreturn]] ~Fatal() {
std::cerr << buffer.str() << std::endl;
// Use _Exit here to avoid calling static destructors. This avoids deadlocks
// in (for example) the thread worker pool, where workers hold a lock while
// performing their work.
_Exit(EXIT_FAILURE);
}
#else
// This variation is a best-effort attempt to make fatal errors recoverable
// for embedders of Binaryen as a library, namely wasm-opt-rs.
//
// Throwing in destructors is strongly discouraged, since it is easy to
// accidentally throw during unwinding, which will trigger an abort. Since
// `Fatal` is a special type that only occurs on error paths, we are hoping it
// is never constructed during unwinding or while destructing another type.
[[noreturn]] ~Fatal() noexcept(false) {
throw std::runtime_error(buffer.str());
}
#endif
};
[[noreturn]] void handle_unreachable(const char* msg = nullptr,
const char* file = nullptr,
unsigned line = 0);
// If control flow reaches the point of the WASM_UNREACHABLE(), the program is
// undefined.
#ifndef NDEBUG
#define WASM_UNREACHABLE(msg) wasm::handle_unreachable(msg, __FILE__, __LINE__)
#elif defined(WASM_BUILTIN_UNREACHABLE)
#define WASM_UNREACHABLE(msg) WASM_BUILTIN_UNREACHABLE
#else
#define WASM_UNREACHABLE(msg) wasm::handle_unreachable()
#endif
} // namespace wasm
#endif // wasm_support_utilities_h
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