This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH] Use ATTRIBUTE_PACKED in ree.c


On 28/11/12 15:05, Jakub Jelinek wrote:
On Wed, Nov 28, 2012 at 03:02:12PM +0000, Richard Earnshaw wrote:
#if (GCC_VERSION < 2007)
# define __attribute__(x)
#endif
...
#ifndef ATTRIBUTE_PACKED
# define ATTRIBUTE_PACKED __attribute__ ((packed))
#endif

So in theory it should expand to nothing for non-GCC compilers.
I've tested (on a short testcase matching what the decl does)
GCCs from 4.8 down back to 3.2 (we support 4.1+ only anyway now)
and clang 3.0.

Jakub


That's not going to help if those other compilers need packedness to eliminate padding. The /old/ ARM ABI used to require that all structs were padded out to 32 bits.

It looks to me as though this code is just non-portable and as such
needs to be rewritten :-(

Why? There is no hard requirement that this must be 2 byte long instead of 4, it is a pure optimization, don't want to waste too much memory unnecessarily.

Jakub



Ah, OK. I read your mail as implying that it didn't work when it wasn't 2 bytes long...

R.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]