cxa_exception_storage.cpp
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//===--------------------- cxa_exception_storage.cpp ----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//
// This file implements the storage for the "Caught Exception Stack"
// https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html#cxx-exc-stack
//
//===----------------------------------------------------------------------===//
#include "cxa_exception.h"
#include <__threading_support>
#if defined(_LIBCXXABI_HAS_NO_THREADS)
namespace __cxxabiv1 {
extern "C" {
static __cxa_eh_globals eh_globals;
__cxa_eh_globals *__cxa_get_globals() { return &eh_globals; }
__cxa_eh_globals *__cxa_get_globals_fast() { return &eh_globals; }
}
}
#elif defined(HAS_THREAD_LOCAL)
namespace __cxxabiv1 {
namespace {
__cxa_eh_globals * __globals () {
static thread_local __cxa_eh_globals eh_globals;
return &eh_globals;
}
}
extern "C" {
__cxa_eh_globals * __cxa_get_globals () { return __globals (); }
__cxa_eh_globals * __cxa_get_globals_fast () { return __globals (); }
}
}
#else
#include "abort_message.h"
#include "fallback_malloc.h"
#if defined(__ELF__) && defined(_LIBCXXABI_LINK_PTHREAD_LIB)
#pragma comment(lib, "pthread")
#endif
// In general, we treat all threading errors as fatal.
// We cannot call std::terminate() because that will in turn
// call __cxa_get_globals() and cause infinite recursion.
namespace __cxxabiv1 {
namespace {
std::__libcpp_tls_key key_;
std::__libcpp_exec_once_flag flag_ = _LIBCPP_EXEC_ONCE_INITIALIZER;
void _LIBCPP_TLS_DESTRUCTOR_CC destruct_ (void *p) {
__free_with_fallback ( p );
if ( 0 != std::__libcpp_tls_set ( key_, NULL ) )
abort_message("cannot zero out thread value for __cxa_get_globals()");
}
void construct_ () {
if ( 0 != std::__libcpp_tls_create ( &key_, destruct_ ) )
abort_message("cannot create thread specific key for __cxa_get_globals()");
}
}
extern "C" {
__cxa_eh_globals * __cxa_get_globals () {
// Try to get the globals for this thread
__cxa_eh_globals* retVal = __cxa_get_globals_fast ();
// If this is the first time we've been asked for these globals, create them
if ( NULL == retVal ) {
retVal = static_cast<__cxa_eh_globals*>
(__calloc_with_fallback (1, sizeof (__cxa_eh_globals)));
if ( NULL == retVal )
abort_message("cannot allocate __cxa_eh_globals");
if ( 0 != std::__libcpp_tls_set ( key_, retVal ) )
abort_message("std::__libcpp_tls_set failure in __cxa_get_globals()");
}
return retVal;
}
// Note that this implementation will reliably return NULL if not
// preceded by a call to __cxa_get_globals(). This is an extension
// to the Itanium ABI and is taken advantage of in several places in
// libc++abi.
__cxa_eh_globals * __cxa_get_globals_fast () {
// First time through, create the key.
if (0 != std::__libcpp_execute_once(&flag_, construct_))
abort_message("execute once failure in __cxa_get_globals_fast()");
// static int init = construct_();
return static_cast<__cxa_eh_globals*>(std::__libcpp_tls_get(key_));
}
}
}
#endif