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Re: -malign-double
- From: Kelley Cook <kelley dot r dot cook at gm dot com>
- To: Jan Hubicka <jh at suse dot cz>, gcc at gcc dot gnu dot org, David Ronis<ronis at ronispc dot chem dot mcgill dot ca>
- Date: Tue, 14 May 2002 17:08:27 -0400
- Subject: Re: -malign-double
- References: <15585.28765.366547.721964@ronispc.chem.mcgill.ca>
>Sorry to be a pest, but nobody answered this the last time I asked:
>
>I've just noticed that the 3.1 documentation for the -malign-double
>flag no longer contain the warning about structures; i.e., it used to
>read:
>
>
>-malign-double'
>`-mno-align-double'
> Control whether GCC aligns `double', `long double', and `long
> long' variables on a two word boundary or a one word boundary.
> Aligning `double' variables on a two word boundary will produce
> code that runs somewhat faster on a `Pentium' at the expense of
> more memory.
>
> *Warning:* if you use the `-malign-double' switch, structures
> containing the above types will be aligned differently than the
> published application binary interface specifications for the 386.
>
>I'd been burned badly by not paying attention to this in the past.
>
>What is the current situation?
>
>David
It disappeared during the checkin of this patch
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/Attic/invoke.texi.diff?r1=1.252&r2=1.253
But the corresponding patch posted to gcc-patches
http://gcc.gnu.org/ml/gcc-patches/2000-12/msg00719.html
doesn't mention this.
Was this intentional?