104 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//8// This file implements the storage for the "Caught Exception Stack"9// https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html#cxx-exc-stack10//11//===----------------------------------------------------------------------===//12 13#include "cxa_exception.h"14 15#include <__thread/support.h>16 17#if defined(_LIBCXXABI_HAS_NO_THREADS)18 19namespace __cxxabiv1 {20extern "C" {21 static __cxa_eh_globals eh_globals;22 __cxa_eh_globals *__cxa_get_globals() { return &eh_globals; }23 __cxa_eh_globals *__cxa_get_globals_fast() { return &eh_globals; }24} // extern "C"25} // namespace __cxxabiv126 27#elif __has_feature(cxx_thread_local)28 29namespace __cxxabiv1 {30namespace {31 __cxa_eh_globals *__globals() {32 static thread_local __cxa_eh_globals eh_globals;33 return &eh_globals;34 }35} // namespace36 37extern "C" {38 __cxa_eh_globals *__cxa_get_globals() { return __globals(); }39 __cxa_eh_globals *__cxa_get_globals_fast() { return __globals(); }40} // extern "C"41} // namespace __cxxabiv142 43#else44 45#include "abort_message.h"46#include "fallback_malloc.h"47 48#if defined(__ELF__) && defined(_LIBCXXABI_LINK_PTHREAD_LIB)49#pragma comment(lib, "pthread")50#endif51 52// In general, we treat all threading errors as fatal.53// We cannot call std::terminate() because that will in turn54// call __cxa_get_globals() and cause infinite recursion.55 56namespace __cxxabiv1 {57namespace {58 std::__libcpp_tls_key key_;59 constinit std::__libcpp_exec_once_flag flag_ = _LIBCPP_EXEC_ONCE_INITIALIZER;60 61 void _LIBCPP_TLS_DESTRUCTOR_CC destruct_(void *p) {62 __free_with_fallback(p);63 if (0 != std::__libcpp_tls_set(key_, NULL))64 __abort_message("cannot zero out thread value for __cxa_get_globals()");65 }66 67 void construct_() {68 if (0 != std::__libcpp_tls_create(&key_, destruct_))69 __abort_message("cannot create thread specific key for __cxa_get_globals()");70 }71} // namespace72 73extern "C" {74 __cxa_eh_globals *__cxa_get_globals() {75 // Try to get the globals for this thread76 __cxa_eh_globals *retVal = __cxa_get_globals_fast();77 78 // If this is the first time we've been asked for these globals, create them79 if (NULL == retVal) {80 retVal = static_cast<__cxa_eh_globals*>(81 __calloc_with_fallback(1, sizeof(__cxa_eh_globals)));82 if (NULL == retVal)83 __abort_message("cannot allocate __cxa_eh_globals");84 if (0 != std::__libcpp_tls_set(key_, retVal))85 __abort_message("std::__libcpp_tls_set failure in __cxa_get_globals()");86 }87 return retVal;88 }89 90 // Note that this implementation will reliably return NULL if not91 // preceded by a call to __cxa_get_globals(). This is an extension92 // to the Itanium ABI and is taken advantage of in several places in93 // libc++abi.94 __cxa_eh_globals *__cxa_get_globals_fast() {95 // First time through, create the key.96 if (0 != std::__libcpp_execute_once(&flag_, construct_))97 __abort_message("execute once failure in __cxa_get_globals_fast()");98 return static_cast<__cxa_eh_globals*>(std::__libcpp_tls_get(key_));99 }100} // extern "C"101} // namespace __cxxabiv1102 103#endif104