1 /* Memory allocation on the stack. 2 Copyright (C) 1995, 1999, 2001-2020 Free Software Foundation, Inc. 3 4 This program is free software: you can redistribute it and/or modify 5 it under the terms of the GNU General Public License as published by 6 the Free Software Foundation; either version 3 of the License, or 7 (at your option) any later version. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 16 17 /* When this file is included, it may be preceded only by preprocessor 18 declarations. Thanks to AIX. Therefore we include it right after 19 "config.h", not later. */ 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 (void* or char*) to N bytes of memory 27 allocated on the stack, and 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 # ifdef __GNUC__ 48 # define alloca __builtin_alloca 49 # else 50 # if defined _AIX 51 #pragma alloca 52 /* Alternatively: #define alloca __alloca, works as well. */ 53 # elif defined _MSC_VER 54 # include <malloc.h> 55 # define alloca _alloca 56 # elif defined __DECC && defined __VMS 57 # define alloca __ALLOCA 58 # elif defined __TANDEM && defined _TNS_E_TARGET 59 # ifdef __cplusplus 60 extern "C" 61 # endif 62 void *_alloca (unsigned short); 63 # pragma intrinsic (_alloca) 64 # define alloca _alloca 65 # elif defined __MVS__ 66 # include <stdlib.h> 67 # else 68 # ifdef __hpux /* This section must match that of bison generated files. */ 69 # ifdef __cplusplus 70 extern "C" void *alloca (unsigned int); 71 # else /* not __cplusplus */ 72 extern void *alloca (); 73 # endif /* not __cplusplus */ 74 # else /* not __hpux */ 75 # ifndef alloca 76 extern char *alloca (); 77 # endif 78 # endif /* __hpux */ 79 # endif 80 # endif 81 #endif 82 83 #endif /* _GL_ALLOCA_H */ 84