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(CELL_P): Also check that the potential pointer is

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correctly aligned for a cell.  Thanks to Miroslav Lichvar!
This commit is contained in:
Marius Vollmer 2006-05-07 22:51:06 +00:00
parent 7f9da94135
commit d3774e2c7f
1 changed files with 11 additions and 1 deletions
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12
libguile/private-gc.h
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@ -163,7 +163,17 @@ int scm_i_gc_grow_heap_p (scm_t_cell_type_statistics * freelist);
#define SCM_MAX(A, B) ((A) > (B) ? (A) : (B))
#define SCM_MIN(A, B) ((A) < (B) ? (A) : (B))
#define CELL_P(x) (SCM_ITAG3 (x) == scm_tc3_cons)
/* CELL_P checks a random word whether it has the right form for a
pointer to a cell. Use scm_i_find_heap_segment_containing_object
to find out whether it actually points to a real cell.
The right form for a cell pointer is this: the low three bits must
be scm_tc3_cons, and when the scm_tc3_cons tag is stripped, the
resulting pointer must be correctly aligned.
scm_i_initialize_heap_segment_data guarantees that the test below
works.
*/
#define CELL_P(x) ((SCM_UNPACK(x) & (sizeof(scm_t_cell)-1)) == scm_tc3_cons)
/*
gc-mark