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| author | Paul Eggert <eggert@cs.ucla.edu> | 2017-10-14 00:55:25 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2017-10-14 01:01:16 -0700 |
| commit | d7038020aa0a868c74cddaed5733ad6eeb73406b (patch) | |
| tree | 31aac82bd20d4d0ceb17eba14723327facb9bccb | |
| parent | ff330530123a9e3f6fbb2d0fe52564e4e3d78369 (diff) | |
| download | emacs-d7038020aa0a868c74cddaed5733ad6eeb73406b.tar.gz | |
Do not under-align pseudovectors
Problem reported by Fabrice Popineau in:
https://lists.gnu.org/archive/html/emacs-devel/2017-10/msg00357.html
Also see diagnosis by Eli Zaretskii in:
https://lists.gnu.org/archive/html/emacs-devel/2017-10/msg00476.html
* src/alloc.c (vector_alignment):
Now a multiple of alignof (max_align_t).
| -rw-r--r-- | src/alloc.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/src/alloc.c b/src/alloc.c index 2e6399e7f8d..da0c3ad4b3e 100644 --- a/src/alloc.c +++ b/src/alloc.c @@ -2923,9 +2923,13 @@ set_next_vector (struct Lisp_Vector *v, struct Lisp_Vector *p) enum { - /* Alignment of struct Lisp_Vector objects. */ - vector_alignment = COMMON_MULTIPLE (FLEXALIGNOF (struct Lisp_Vector), - GCALIGNMENT), + /* Alignment of struct Lisp_Vector objects. Because pseudovectors + can contain any C type, align at least as strictly as + max_align_t. On x86 and x86-64 this can waste up to 8 bytes + for typical vectors, since alignof (max_align_t) is 16 but + typical vectors need only an alignment of 8. However, it is + not worth the hassle to avoid wasting those bytes. */ + vector_alignment = COMMON_MULTIPLE (alignof (max_align_t), GCALIGNMENT), /* Vector size requests are a multiple of this. */ roundup_size = COMMON_MULTIPLE (vector_alignment, word_size) |