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Fix alignment bug with pure bignums

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Problem found on 32-bit sparc, which has stricter alignment
checking than x86-64.
* src/alloc.c (pure_alloc): When TYPE is negative it now specifies
the negation of the required alignment of the result.
(make_pure_bignum): Specify bignum limb alignment.
This commit is contained in:
Paul Eggert 2019-03-25 14:31:31 -07:00
parent 389475dbcc
commit db53731c5f
1 changed files with 9 additions and 4 deletions
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13
src/alloc.c
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@ -5342,7 +5342,8 @@ valid_lisp_object_p (Lisp_Object obj)
/* Allocate room for SIZE bytes from pure Lisp storage and return a
pointer to it. TYPE is the Lisp type for which the memory is
allocated. TYPE < 0 means it's not used for a Lisp object. */
allocated. TYPE < 0 means it's not used for a Lisp object,
and that the result should have an alignment of -TYPE. */
static void *
pure_alloc (size_t size, int type)
@ -5361,8 +5362,11 @@ pure_alloc (size_t size, int type)
{
/* Allocate space for a non-Lisp object from the end of the free
space. */
pure_bytes_used_non_lisp += size;
result = purebeg + pure_size - pure_bytes_used_non_lisp;
ptrdiff_t unaligned_non_lisp = pure_bytes_used_non_lisp + size;
char *unaligned = purebeg + pure_size - unaligned_non_lisp;
int decr = (intptr_t) unaligned & (-1 - type);
pure_bytes_used_non_lisp = unaligned_non_lisp + decr;
result = unaligned - decr;
}
pure_bytes_used = pure_bytes_used_lisp + pure_bytes_used_non_lisp;
@ -5549,7 +5553,8 @@ make_pure_bignum (struct Lisp_Bignum *value)
struct Lisp_Bignum *b = pure_alloc (sizeof *b, Lisp_Vectorlike);
XSETPVECTYPESIZE (b, PVEC_BIGNUM, 0, VECSIZE (struct Lisp_Bignum));
pure_limbs = pure_alloc (nbytes, -1);
int limb_alignment = alignof (mp_limb_t);
pure_limbs = pure_alloc (nbytes, - limb_alignment);
for (i = 0; i < nlimbs; ++i)
pure_limbs[i] = mpz_getlimbn (value->value, i);