* Re: [Emacs-diffs] trunk r117897: Port USE_LOCAL_ALLOCATORS code to clang 3.4 x86-64.
[not found] <E1XUQ8O-0008RX-K8@vcs.savannah.gnu.org>
@ 2014-09-18 2:43 ` Stefan Monnier
2014-09-18 5:42 ` Paul Eggert
0 siblings, 1 reply; 2+ messages in thread
From: Stefan Monnier @ 2014-09-18 2:43 UTC (permalink / raw)
To: Paul Eggert; +Cc: emacs-devel
> +/* Alignment fixup needed for alloca. GCC aligns alloca properly already,
> + Clang sometimes doesn't, and play it safe for other random compilers. */
> +# if __GNUC__ && !__clang__
> +enum { ALLOCA_FIXUP = 0 };
> +# else
> +enum { ALLOCA_FIXUP = GCALIGNMENT - 1 };
> +# endif
> +
> +/* Declare a void * variable PTR and set it to a properly-aligned array of
> + N newly allocated bytes with function lifetime. */
> +# define LOCAL_ALLOCA(ptr, n) \
> + void *ptr = alloca ((n) + ALLOCA_FIXUP); \
> + ptr = (void *) ((intptr_t) ptr_ & ~(ALLOCA_FIXUP))
I find this hideous. I'd prefer we just don't use alloca in
those cases where alignment would be a problem.
Stefan
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [Emacs-diffs] trunk r117897: Port USE_LOCAL_ALLOCATORS code to clang 3.4 x86-64.
2014-09-18 2:43 ` [Emacs-diffs] trunk r117897: Port USE_LOCAL_ALLOCATORS code to clang 3.4 x86-64 Stefan Monnier
@ 2014-09-18 5:42 ` Paul Eggert
0 siblings, 0 replies; 2+ messages in thread
From: Paul Eggert @ 2014-09-18 5:42 UTC (permalink / raw)
To: Stefan Monnier; +Cc: emacs-devel
Stefan Monnier wrote:
> I'd prefer we just don't use alloca in
> those cases where alignment would be a problem.
It's certainly simpler that way. I changed lisp.h to do that in trunk
bzr 117898.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2014-09-18 2:43 ` [Emacs-diffs] trunk r117897: Port USE_LOCAL_ALLOCATORS code to clang 3.4 x86-64 Stefan Monnier
2014-09-18 5:42 ` Paul Eggert
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