1 /* Memory allocation on the stack.
2
3 Copyright (C) 1995, 1999, 2001-2004, 2006-2023 Free Software Foundation,
4 Inc.
5
6 This file is free software: you can redistribute it and/or modify
7 it under the terms of the GNU Lesser General Public License as
8 published by the Free Software Foundation; either version 2.1 of the
9 License, or (at your option) any later version.
10
11 This file 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
14 GNU Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public License
17 along with this program. If not, see <https://www.gnu.org/licenses/>. */
18
19 /* Avoid using the symbol _ALLOCA_H here, as Bison assumes _ALLOCA_H
20 means there is a real alloca function. */
21 #ifndef _GL_ALLOCA_H
22 #define _GL_ALLOCA_H
23
24 /* alloca (N) returns a pointer to N bytes of memory
25 allocated on the stack, which will last until the function returns.
26 Use of alloca should be avoided:
27 - inside arguments of function calls - undefined behaviour,
28 - in inline functions - the allocation may actually last until the
29 calling function returns,
30 - for huge N (say, N >= 65536) - you never know how large (or small)
31 the stack is, and when the stack cannot fulfill the memory allocation
32 request, the program just crashes.
33 */
34
35 #ifndef alloca
36 /* Some version of mingw have an <alloca.h> that causes trouble when
37 included after 'alloca' gets defined as a macro. As a workaround,
38 include this <alloca.h> first and define 'alloca' as a macro afterwards
39 if needed. */
40 # if defined __GNUC__ && (defined _WIN32 && ! defined __CYGWIN__) && @HAVE_ALLOCA_H@
41 # include_next <alloca.h>
42 # endif
43 #endif
44 #ifndef alloca
45 # if defined __GNUC__ || (__clang_major__ >= 4)
46 # define alloca __builtin_alloca
47 # elif defined _AIX
48 # define alloca __alloca
49 # elif defined _MSC_VER
50 # include <malloc.h>
51 # define alloca _alloca
52 # elif defined __DECC && defined __VMS
53 # define alloca __ALLOCA
54 # elif defined __TANDEM && defined _TNS_E_TARGET
55 # ifdef __cplusplus
56 extern "C"
57 # endif
58 void *_alloca (unsigned short);
59 # pragma intrinsic (_alloca)
60 # define alloca _alloca
61 # elif defined __MVS__
62 # include <stdlib.h>
63 # else
64 # include <stddef.h>
65 # ifdef __cplusplus
66 extern "C"
67 # endif
68 void *alloca (size_t);
69 # endif
70 #endif
71
72 #endif /* _GL_ALLOCA_H */