// Support routines for the -*- C++ -*- dynamic memory management. // Copyright (C) 1997-2022 Free Software Foundation, Inc. // // This file is part of GCC. // // GCC is free software; you can redistribute it and/or modify // it under the terms of the GNU General Public License as published by // the Free Software Foundation; either version 3, or (at your option) // any later version. // // GCC is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // . #include #include #include #include #include "new" #if !_GLIBCXX_HAVE_ALIGNED_ALLOC && !_GLIBCXX_HAVE__ALIGNED_MALLOC \ && !_GLIBCXX_HAVE_POSIX_MEMALIGN && _GLIBCXX_HAVE_MEMALIGN # if _GLIBCXX_HOSTED && __has_include() // Some C libraries declare memalign in # include # else extern "C" void *memalign(std::size_t boundary, std::size_t size); # endif #endif using std::new_handler; using std::bad_alloc; #if ! _GLIBCXX_HOSTED using std::size_t; extern "C" { # if _GLIBCXX_HAVE_POSIX_MEMALIGN int posix_memalign(void **, size_t alignment, size_t size); # elif _GLIBCXX_HAVE_ALIGNED_ALLOC void *aligned_alloc(size_t alignment, size_t size); # elif _GLIBCXX_HAVE__ALIGNED_MALLOC void *_aligned_malloc(size_t size, size_t alignment); # elif _GLIBCXX_HAVE_MEMALIGN void *memalign(size_t alignment, size_t size); # else // A freestanding C runtime may not provide "malloc" -- but there is no // other reasonable way to implement "operator new". void *malloc(size_t); # endif } #endif namespace __gnu_cxx { // Prefer posix_memalign if available, because it's older than aligned_alloc // and so more likely to be provided by replacement malloc libraries that // predate the addition of aligned_alloc. See PR libstdc++/113258. #if _GLIBCXX_HAVE_POSIX_MEMALIGN static inline void* aligned_alloc (std::size_t al, std::size_t sz) { void *ptr; // posix_memalign has additional requirement, not present on aligned_alloc: // The value of alignment shall be a power of two multiple of sizeof(void *). if (al < sizeof(void*)) al = sizeof(void*); int ret = posix_memalign (&ptr, al, sz); if (ret == 0) return ptr; return nullptr; } #elif _GLIBCXX_HAVE_ALIGNED_ALLOC using ::aligned_alloc; #elif _GLIBCXX_HAVE__ALIGNED_MALLOC static inline void* aligned_alloc (std::size_t al, std::size_t sz) { return _aligned_malloc(sz, al); } #elif _GLIBCXX_HAVE_MEMALIGN static inline void* aligned_alloc (std::size_t al, std::size_t sz) { // Solaris requires al >= sizeof a word and QNX requires >= sizeof(void*) // but they both provide posix_memalign, so will use the definition above. return memalign (al, sz); } #else // !HAVE__ALIGNED_MALLOC && !HAVE_POSIX_MEMALIGN && !HAVE_MEMALIGN // The C library doesn't provide any aligned allocation functions, define one. // This is a modified version of code from gcc/config/i386/gmm_malloc.h static inline void* aligned_alloc (std::size_t al, std::size_t sz) { // We need extra bytes to store the original value returned by malloc. if (al < sizeof(void*)) al = sizeof(void*); void* const malloc_ptr = malloc(sz + al); if (!malloc_ptr) return nullptr; // Align to the requested value, leaving room for the original malloc value. void* const aligned_ptr = (void *) (((uintptr_t) malloc_ptr + al) & -al); // Store the original malloc value where it can be found by operator delete. ((void **) aligned_ptr)[-1] = malloc_ptr; return aligned_ptr; } #endif } // namespace __gnu_cxx _GLIBCXX_WEAK_DEFINITION void * operator new (std::size_t sz, std::align_val_t al) { std::size_t align = (std::size_t)al; /* Alignment must be a power of two. */ /* XXX This should be checked by the compiler (PR 86878). */ if (__builtin_expect (!std::__has_single_bit(align), false)) _GLIBCXX_THROW_OR_ABORT(bad_alloc()); /* malloc (0) is unpredictable; avoid it. */ if (__builtin_expect (sz == 0, false)) sz = 1; #if _GLIBCXX_HAVE_POSIX_MEMALIGN #elif _GLIBCXX_HAVE_ALIGNED_ALLOC # if defined _AIX || defined __APPLE__ /* AIX 7.2.0.0 aligned_alloc incorrectly has posix_memalign's requirement * that alignment is a multiple of sizeof(void*). * OS X 10.15 has the same requirement. */ if (align < sizeof(void*)) align = sizeof(void*); # endif /* C11: the value of size shall be an integral multiple of alignment. */ sz = (sz + align - 1) & ~(align - 1); #endif void *p; while ((p = __gnu_cxx::aligned_alloc (align, sz)) == nullptr) { new_handler handler = std::get_new_handler (); if (! handler) _GLIBCXX_THROW_OR_ABORT(bad_alloc()); handler (); } return p; }