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| author | Paul Eggert <eggert@cs.ucla.edu> | 2018-09-06 19:17:14 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2018-09-06 23:56:13 -0700 |
| commit | 2c8520e19c0fe72d046033e39953b7a0a87be24e (patch) | |
| tree | 2ea12495ed8184e87108e17632ecd8c2ab02c8cf /src/alloc.c | |
| parent | bca35315e16cb53415649e5c0ac2ec0cc1368679 (diff) | |
| download | emacs-2c8520e19c0fe72d046033e39953b7a0a87be24e.tar.gz | |
Shrink pseudovectors a bit
sizeof (struct Lisp_Marker) was 32 on x86, where 24 would do.
Problem noted by Stefan Monnier in:
https://lists.gnu.org/r/emacs-devel/2018-09/msg00165.html
* src/bignum.h (struct Lisp_Bignum):
* src/frame.h (struct frame):
* src/lisp.h (struct Lisp_Vector, struct Lisp_Bool_Vector)
(struct Lisp_Char_Table, struct Lisp_Hash_Table)
(struct Lisp_Marker, struct Lisp_Overlay)
(struct Lisp_Misc_Ptr, struct Lisp_User_Ptr)
(struct Lisp_Finalizer, struct Lisp_Float)
(struct Lisp_Module_Function):
* src/process.h (struct Lisp_Process):
* src/termhooks.h (struct terminal):
* src/thread.h (struct thread_state, struct Lisp_Mutex)
(struct Lisp_CondVar):
* src/window.c (struct save_window_data):
* src/window.h (struct window):
* src/xterm.h (struct scroll_bar):
* src/xwidget.h (struct xwidget, struct xwidget_view):
Add GCALIGNED_STRUCT attribute.
* src/lisp.h (GCALIGNED_UNION_MEMBER): Renamed from GCALIGNED_UNION.
All uses changed.
(GCALIGNED_STRUCT_MEMBER, GCALIGNED_STRUCT, GCALIGNED): New macros.
All uses of open-coded GCALIGNED changed to use GCALIGNED.
(union vectorlike_header): No longer GC-aligned.
(PSEUDOVECSIZE): Yield 0 for pseudovectors without Lisp
objects that place a member before where the first Lisp object
member would be.
Diffstat (limited to 'src/alloc.c')
| -rw-r--r-- | src/alloc.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/src/alloc.c b/src/alloc.c index 28ca7804ee9..abb98a9eb68 100644 --- a/src/alloc.c +++ b/src/alloc.c @@ -641,9 +641,11 @@ buffer_memory_full (ptrdiff_t nbytes) implement Lisp objects; since pseudovectors can contain any C type, this is max_align_t. On recent GNU/Linux x86 and x86-64 this can often waste up to 8 bytes, 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 this waste. */ -enum { LISP_ALIGNMENT = alignof (union { max_align_t x; GCALIGNED_UNION }) }; + typical vectors need only an alignment of 8. Although shrinking + the alignment to 8 would save memory, it cost a 20% hit to Emacs + CPU performance on Fedora 28 x86-64 when compiled with gcc -m32. */ +enum { LISP_ALIGNMENT = alignof (union { max_align_t x; + GCALIGNED_UNION_MEMBER }) }; verify (LISP_ALIGNMENT % GCALIGNMENT == 0); /* True if malloc (N) is known to return storage suitably aligned for |