Re: PATCH: Define MALLOC_ALIGNMENT as 16 for x32

[Andreas Jaeger <aj at suse dot com>]

On 05/18/2012 10:55 PM, H.J. Lu wrote:
> On Tue, May 15, 2012 at 10:04 AM, Roland McGrath<roland@hack.frob.com>  wrote:
> > I don't think that's the right way to do it.
> > How about this instead?
> >
> > diff --git a/malloc/malloc.c b/malloc/malloc.c
> > index 79cdc52..0000000 100644
> > --- a/malloc/malloc.c
> > +++ b/malloc/malloc.c
> > @@ -337,16 +337,20 @@ __malloc_assert (const char *assertion,
> >
> >
> >   #ifndef MALLOC_ALIGNMENT
> > -/* XXX This is the correct definition.  It differs from 2*SIZE_SZ only on
> > -   powerpc32.  For the time being, changing this is causing more
> > -   compatibility problems due to malloc_get_state/malloc_set_state than
> > -   will returning blocks not adequately aligned for long double objects
> > -   under -mlong-double-128.
> > +# if !SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_16)
> > +/* This is the correct definition when there is no past ABI to constrain it.
> >
> > -#define MALLOC_ALIGNMENT       (2 * SIZE_SZ<  __alignof__ (long double) \
> > -                               ? __alignof__ (long double) : 2 * SIZE_SZ)
> > -*/
> > -#define MALLOC_ALIGNMENT       (2 * SIZE_SZ)
> > +   Among configurations with a past ABI constraint, it differs from
> > +   2*SIZE_SZ only on powerpc32.  For the time being, changing this is
> > +   causing more compatibility problems due to malloc_get_state and
> > +   malloc_set_state than will returning blocks not adequately aligned for
> > +   long double objects under -mlong-double-128.  */
> > +
> > +#  define MALLOC_ALIGNMENT       (2 * SIZE_SZ<  __alignof__ (long double) \
> > +                                 ? __alignof__ (long double) : 2 * SIZE_SZ)
> > +# else
> > +#  define MALLOC_ALIGNMENT       (2 * SIZE_SZ)
> > +# endif
> >   #endif
> >
> >   /* The corresponding bit mask value */
>
> Hi Roland,
>
> I verified that it works for x32.  Can you check it in?

this fails for me on Linux/x86-64, it needs an include <shlib-compat.h>.

I'll commit the following as obvious now,

Andreas
2012-05-21  Andreas Jaeger  <aj@suse.de>

	* malloc/malloc.c: Include shlib-compat.h for SHLIB_COMPAT.

diff --git a/malloc/malloc.c b/malloc/malloc.c
index c216d26..7115287 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -228,6 +228,8 @@
 #include <stdio.h>    /* needed for malloc_stats */
 #include <errno.h>

+#include <shlib-compat.h>
+
 /* For uintptr_t.  */
 #include <stdint.h>


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