Hello Ludovic,
- GC_REGISTER_DISPLACEMENT (2*sizeof(scm_t_bits)); /* for the self data
pointer */
- GC_REGISTER_DISPLACEMENT (2*sizeof(scm_t_bits)
- + scm_tc3_struct); /* for the vtable data
pointer */
+ /* The first word of a struct is equal to `SCM_STRUCT_DATA (vtable) +
+ scm_tc3_struct', and `SCM_STRUCT_DATA (vtable)' is 2 words after
VTABLE by
+ default. */
+ GC_REGISTER_DISPLACEMENT (2 * sizeof (scm_t_bits) + scm_tc3_struct);
I'm pretty sure the first case is still needed, for instance
reallocation. It is, as the comment indicates, "for the self data
pointer" -- the second word of the object, which normally points to the
third word of the object, but for reallocated instances points to the
third word of *another* object. See my article on redefining classes for
more info.
Can you change this?
Andy
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