From 8271aa5335668a1dc62168a4e90b4554bd3a0ca7 Mon Sep 17 00:00:00 2001 From: Shoaib Meenai Date: Mon, 21 Nov 2022 15:59:42 -0800 Subject: [PATCH] [libcxxabi] Always use thread_local for cxa_exception_storage This was previously guarded by HAS_THREAD_LOCAL, which was never set by CMake and had to be specified manually. Android has been setting this to solve https://github.com/android/ndk/issues/1200 [1], but every compiler and platform libc++abi supports should have thread_local by now, so we can just get rid of the fallback implementation and simplify things significantly (including removing the now unused fallback calloc). [1] https://android-review.googlesource.com/c/toolchain/llvm-project/+/1285596 Reviewed By: #libc_abi, MaskRay, ldionne Differential Revision: https://reviews.llvm.org/D138461 --- libcxxabi/src/cxa_exception_storage.cpp | 70 ++----------------------- libcxxabi/src/fallback_malloc.cpp | 11 ---- libcxxabi/src/fallback_malloc.h | 3 -- 3 files changed, 4 insertions(+), 80 deletions(-) diff --git a/libcxxabi/src/cxa_exception_storage.cpp b/libcxxabi/src/cxa_exception_storage.cpp index 3a3233a1b927..1abf6143e59f 100644 --- a/libcxxabi/src/cxa_exception_storage.cpp +++ b/libcxxabi/src/cxa_exception_storage.cpp @@ -12,21 +12,18 @@ #include "cxa_exception.h" -#include <__threading_support> +namespace __cxxabiv1 { #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; } } // extern "C" -} // namespace __cxxabiv1 -#elif defined(HAS_THREAD_LOCAL) +#else -namespace __cxxabiv1 { namespace { __cxa_eh_globals *__globals() { static thread_local __cxa_eh_globals eh_globals; @@ -38,66 +35,7 @@ extern "C" { __cxa_eh_globals *__cxa_get_globals() { return __globals(); } __cxa_eh_globals *__cxa_get_globals_fast() { return __globals(); } } // extern "C" -} // namespace __cxxabiv1 - -#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()"); - } -} // namespace - -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()"); - return static_cast<__cxa_eh_globals*>(std::__libcpp_tls_get(key_)); - } -} // extern "C" -} // namespace __cxxabiv1 #endif + +} // namespace __cxxabiv1 diff --git a/libcxxabi/src/fallback_malloc.cpp b/libcxxabi/src/fallback_malloc.cpp index 591efbefc8a5..759bb58f7c30 100644 --- a/libcxxabi/src/fallback_malloc.cpp +++ b/libcxxabi/src/fallback_malloc.cpp @@ -270,17 +270,6 @@ void* __aligned_malloc_with_fallback(size_t size) { return fallback_malloc(size); } -void* __calloc_with_fallback(size_t count, size_t size) { - void* ptr = ::calloc(count, size); - if (NULL != ptr) - return ptr; - // if calloc fails, fall back to emergency stash - ptr = fallback_malloc(size * count); - if (NULL != ptr) - ::memset(ptr, 0, size * count); - return ptr; -} - void __aligned_free_with_fallback(void* ptr) { if (is_fallback_ptr(ptr)) fallback_free(ptr); diff --git a/libcxxabi/src/fallback_malloc.h b/libcxxabi/src/fallback_malloc.h index 816e691ed231..528014b3456d 100644 --- a/libcxxabi/src/fallback_malloc.h +++ b/libcxxabi/src/fallback_malloc.h @@ -17,9 +17,6 @@ namespace __cxxabiv1 { // Allocate some memory from _somewhere_ _LIBCXXABI_HIDDEN void * __aligned_malloc_with_fallback(size_t size); -// Allocate and zero-initialize memory from _somewhere_ -_LIBCXXABI_HIDDEN void * __calloc_with_fallback(size_t count, size_t size); - _LIBCXXABI_HIDDEN void __aligned_free_with_fallback(void *ptr); _LIBCXXABI_HIDDEN void __free_with_fallback(void *ptr);