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Re: __HAVE_BUILTIN_SETJMP__: why?
- From: Fergus Henderson <fjh at cs dot mu dot OZ dot AU>
- To: gcc at gcc dot gnu dot org
- Date: Wed, 15 May 2002 13:39:52 +1000
- Subject: Re: __HAVE_BUILTIN_SETJMP__: why?
Zack Weinberg writes:
> cpplib unconditionally defines __HAVE_BUILTIN_SETJMP__ to 1. This was
> added back in 1996:
>
> Sat Jan 27 07:59:25 1996 Richard Kenner (kenner@vlsi1.ultra.nyu.edu)
>
> * tree.h (enum built_in_function): Add BUILT_IN_{SET,LONG}JMP.
> * expr.c: Include hard-reg-set.h.
> (arg_pointer_save_area): New declaration.
> (expand_builtin, case BUILT_IN_{SET,LONG}JMP): New cases.
> * Makefile.in (expr.o): Includes hard-reg-set.h.
> * c-decl.c (init_decl_processing): Add definitions for
> __builtin_setjmp and __builtin_longjmp.
> * cccp.c (initialize_builtins): Add def of __HAVE_BUILTIN_SETJMP__.
>
> I can find no references to this macro anywhere. What was it for?
Presumably it was so people who wanted to use __builtin_setjmp() could write
#ifdef __HAVE_BUILTIN_SETJMP__
/* the fast version -- use GCC's __builtin_setjmp() */
#define my_setjmp __builtin_setjmp
#define my_longjmp __builtin_longjmp
typedef void *my_jmpbuf[5];
#else
/* the portable version -- use the standard ANSI/ISO C setjmp() */
#include <setjmp.h>
#define my_setjmp setjmp
#define my_longjmp longjmp
typedef jmpbuf_t my_jmpbuf;
#endif
You could use something like
#if (__GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 8))
instead of
#ifdef __HAVE_BUILTIN_SETJMP__
so it is not strictly necessary, but the definition of __HAVE_BUILTIN_SETJMP__
is pretty harmless, so personally I would leave it in to avoid breaking any
existing code which relies on it.
--
Fergus Henderson <fjh@cs.mu.oz.au> | "I have always known that the pursuit
The University of Melbourne | of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh> | -- the last words of T. S. Garp.