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(scm_remember_upto_here_1, scm_remember_upto_here_2) [__GNUC__]:

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Use volatile asm macros rather than a function call.
This commit is contained in:
Kevin Ryde 2003-08-12 21:08:34 +00:00
parent 34b6177b15
commit aca3618f81
1 changed files with 20 additions and 0 deletions
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20
libguile/gc.h
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@ -341,6 +341,26 @@ SCM_API char *scm_gc_strndup (const char *str, size_t n, const char *what);
SCM_API void scm_remember_upto_here_1 (SCM obj);
SCM_API void scm_remember_upto_here_2 (SCM obj1, SCM obj2);
SCM_API void scm_remember_upto_here (SCM obj1, ...);
/* In GCC we can force a reference to an SCM with a little do-nothing asm,
avoiding the code size and slowdown of an actual function call.
__volatile__ ensures nothing will be moved across the reference, and that
it won't be optimized away (or rather only if proved unreachable).
Unfortunately there doesn't seem to be any way to do the varargs
scm_remember_upto_here similarly. */
#ifdef __GNUC__
#define scm_remember_upto_here_1(x) \
do { \
__asm__ __volatile__ ("" : : "g" (x)); \
} while (0)
#define scm_remember_upto_here_2(x, y) \
do { \
scm_remember_upto_here_1 (x); \
scm_remember_upto_here_1 (y); \
} while (0)
#endif
SCM_API SCM scm_return_first (SCM elt, ...);
SCM_API int scm_return_first_int (int x, ...);
SCM_API SCM scm_permanent_object (SCM obj);