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//===- subzero/src/IceTLS.h - thread_local workaround -----------*- C++ -*-===//
//
// The Subzero Code Generator
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief Defines macros for working around the lack of support for
/// thread_local in MacOS 10.6.
///
/// This assumes std::thread is written in terms of pthread. Define
/// ICE_THREAD_LOCAL_HACK to enable the pthread workarounds.
///
//===----------------------------------------------------------------------===//
#ifndef SUBZERO_SRC_ICETLS_H
#define SUBZERO_SRC_ICETLS_H
///
/// @defgroup /IceTLS Defines 5 macros for unifying thread_local and pthread:
/// @{
///
/// \def ICE_TLS_DECLARE_FIELD(Type, FieldName)
/// Declare a static thread_local field inside the current class definition.
/// "Type" needs to be a pointer type, such as int* or class Foo*.
///
/// \def ICE_TLS_DEFINE_FIELD(Type, ClassName, FieldName)
/// Define a static thread_local field outside of its class definition. The
/// field will ultimately be initialized to nullptr.
///
/// \def ICE_TLS_INIT_FIELD(FieldName)
/// Ensure the thread_local field is properly initialized. This is intended
/// to be called from within a static method of the field's class after main()
/// starts (to ensure that the pthread library is fully initialized) but before
/// any uses of ICE_TLS_GET_FIELD or ICE_TLS_SET_FIELD.
///
/// \def ICE_TLS_GET_FIELD(Type, FieldName)
/// Read the value of the static thread_local field. Must be done within the
/// context of its class.
///
/// \def ICE_TLS_SET_FIELD(FieldName, Value)
/// Write a value into the static thread_local field. Must be done within the
/// context of its class.
/// TODO(stichnot): Limit this define to only the platforms that absolutely
/// require it. And ideally, eventually remove this hack altogether.
///
///
/// \def ICE_THREAD_LOCAL_HACK
///
#ifndef ICE_THREAD_LOCAL_HACK
#define ICE_THREAD_LOCAL_HACK 1
#endif
#if ICE_THREAD_LOCAL_HACK
// For a static thread_local field F of a class C, instead of declaring and
// defining C::F, we create two static fields:
// static pthread_key_t F__key;
// static int F__initStatus;
//
// The F__initStatus field is used to hold the result of the
// pthread_key_create() call, where a zero value indicates success, and a
// nonzero value indicates failure or that ICE_TLS_INIT_FIELD() was never
// called. The F__key field is used as the argument to pthread_getspecific()
// and pthread_setspecific().
#include "llvm/Support/ErrorHandling.h"
#include <pthread.h>
#define ICE_TLS_DECLARE_FIELD(Type, FieldName) \
using FieldName##__type = Type; \
static pthread_key_t FieldName##__key; \
static int FieldName##__initStatus
#define ICE_TLS_DEFINE_FIELD(Type, ClassName, FieldName) \
pthread_key_t ClassName::FieldName##__key; \
int ClassName::FieldName##__initStatus = 1
#define ICE_TLS_INIT_FIELD(FieldName) \
if (FieldName##__initStatus) { \
FieldName##__initStatus = pthread_key_create(&FieldName##__key, nullptr); \
if (FieldName##__initStatus) \
llvm::report_fatal_error("Failed to create pthread key"); \
}
#define ICE_TLS_GET_FIELD(FieldName) \
(assert(FieldName##__initStatus == 0), \
static_cast<FieldName##__type>(pthread_getspecific(FieldName##__key)))
#define ICE_TLS_SET_FIELD(FieldName, Value) \
(assert(FieldName##__initStatus == 0), \
pthread_setspecific(FieldName##__key, (Value)))
#else // !ICE_THREAD_LOCAL_HACK
#if defined(_MSC_VER)
#define ICE_ATTRIBUTE_TLS __declspec(thread)
#else // !_MSC_VER
#define ICE_ATTRIBUTE_TLS thread_local
#endif // !_MSC_VER
#define ICE_TLS_DECLARE_FIELD(Type, FieldName) \
static ICE_ATTRIBUTE_TLS Type FieldName
#define ICE_TLS_DEFINE_FIELD(Type, ClassName, FieldName) \
ICE_ATTRIBUTE_TLS Type ClassName::FieldName = nullptr
#define ICE_TLS_INIT_FIELD(FieldName)
#define ICE_TLS_GET_FIELD(FieldName) (FieldName)
#define ICE_TLS_SET_FIELD(FieldName, Value) (FieldName = (Value))
#endif // !ICE_THREAD_LOCAL_HACK
///
/// @}
///
#endif // SUBZERO_SRC_ICETLS_H