1 /* Memory allocation on the stack. 2 3 Copyright (C) 1995, 1999, 2001-2004, 2006-2021 Free Software Foundation, 4 Inc. 5 6 This program is free software; you can redistribute it and/or modify it 7 under the terms of the GNU General Public License as published 8 by the Free Software Foundation; either version 3, or (at your option) 9 any later version. 10 11 This program is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public 17 License along with this program; if not, see 18 <https://www.gnu.org/licenses/>. 19 */ 20 21 /* Avoid using the symbol _ALLOCA_H here, as Bison assumes _ALLOCA_H 22 means there is a real alloca function. */ 23 #ifndef _GL_ALLOCA_H 24 #define _GL_ALLOCA_H 25 26 /* alloca (N) returns a pointer to N bytes of memory 27 allocated on the stack, which will last until the function returns. 28 Use of alloca should be avoided: 29 - inside arguments of function calls - undefined behaviour, 30 - in inline functions - the allocation may actually last until the 31 calling function returns, 32 - for huge N (say, N >= 65536) - you never know how large (or small) 33 the stack is, and when the stack cannot fulfill the memory allocation 34 request, the program just crashes. 35 */ 36 37 #ifndef alloca 38 /* Some version of mingw have an <alloca.h> that causes trouble when 39 included after 'alloca' gets defined as a macro. As a workaround, 40 include this <alloca.h> first and define 'alloca' as a macro afterwards 41 if needed. */ 42 # if defined __GNUC__ && (defined _WIN32 && ! defined __CYGWIN__) && @HAVE_ALLOCA_H@ 43 # include_next <alloca.h> 44 # endif 45 #endif 46 #ifndef alloca 47 # if defined __GNUC__ || (__clang_major__ >= 4) 48 # define alloca __builtin_alloca 49 # elif defined _AIX 50 # define alloca __alloca 51 # elif defined _MSC_VER 52 # include <malloc.h> 53 # define alloca _alloca 54 # elif defined __DECC && defined __VMS 55 # define alloca __ALLOCA 56 # elif defined __TANDEM && defined _TNS_E_TARGET 57 # ifdef __cplusplus 58 extern "C" 59 # endif 60 void *_alloca (unsigned short); 61 # pragma intrinsic (_alloca) 62 # define alloca _alloca 63 # elif defined __MVS__ 64 # include <stdlib.h> 65 # else 66 # include <stddef.h> 67 # ifdef __cplusplus 68 extern "C" 69 # endif 70 void *alloca (size_t); 71 # endif 72 #endif 73 74 #endif /* _GL_ALLOCA_H */ 75