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Be more aggressive in marking objects during GC

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Simplified version of a patch from Pip Cet (Bug#41321#299).
* src/alloc.c (maybe_lisp_pointer): Remove.  All uses removed.
(mark_memory): Also look at the pointer offset by ‘lispsym’,
for symbols.
This commit is contained in:
Paul Eggert 2020-05-31 15:29:23 -07:00
parent 36f508f589
commit 68b6dad1d8
1 changed files with 10 additions and 16 deletions
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26
src/alloc.c
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@ -4585,18 +4585,6 @@ mark_maybe_objects (Lisp_Object const *array, ptrdiff_t nelts)
mark_maybe_object (*array);
}
/* Return true if P might point to Lisp data that can be garbage
collected, and false otherwise (i.e., false if it is easy to see
that P cannot point to Lisp data that can be garbage collected).
Symbols are implemented via offsets not pointers, but the offsets
are also multiples of LISP_ALIGNMENT. */
static bool
maybe_lisp_pointer (void *p)
{
return (uintptr_t) p % LISP_ALIGNMENT == 0;
}
/* If P points to Lisp data, mark that as live if it isn't already
marked. */
@ -4609,9 +4597,6 @@ mark_maybe_pointer (void *p)
VALGRIND_MAKE_MEM_DEFINED (&p, sizeof (p));
#endif
if (!maybe_lisp_pointer (p))
return;
if (pdumper_object_p (p))
{
int type = pdumper_find_object_type (p);
@ -4715,7 +4700,16 @@ mark_memory (void const *start, void const *end)
for (pp = start; (void const *) pp < end; pp += GC_POINTER_ALIGNMENT)
{
mark_maybe_pointer (*(void *const *) pp);
char *p = *(char *const *) pp;
mark_maybe_pointer (p);
/* Unmask any struct Lisp_Symbol pointer that make_lisp_symbol
previously disguised by adding the address of 'lispsym'.
On a host with 32-bit pointers and 64-bit Lisp_Objects,
a Lisp_Object might be split into registers saved into
non-adjacent words and P might be the low-order word's value. */
p += (intptr_t) lispsym;
mark_maybe_pointer (p);
verify (alignof (Lisp_Object) % GC_POINTER_ALIGNMENT == 0);
if (alignof (Lisp_Object) == GC_POINTER_ALIGNMENT