------- Comment #16 from pinskia at gmail dot com 2008-12-15 21:39 ------- Subject: Re: Gcc misaligns arrays when stack is forced follow the x8632 ABI
Sent from my iPhone On Dec 15, 2008, at 1:33 PM, "whaley at cs dot utsa dot edu" <[email protected] > wrote: > > > ------- Comment #15 from whaley at cs dot utsa dot edu 2008-12-15 > 21:32 ------- >> GCC chose to change the *unwritten* standard for the ABI in use for >> IA32 GNU/Linux. > > This is not true. Prior to this change, gcc followed the *written* > standard > provided by the LSB. LSB was written years after we had already did this back in gcc 3.0. Please check the history before saying gcc followed a written standard when none existed when this change was done. > You chose to violate the standard, or to put as you seem > to prefer, you chose to declare that you followed no standard, as > the written > standard previously used by pretty much all OSes on the x86 was > suddenly > unusable. > >> The SCO document may have been useful before SSE, but processor >> architecture and language developments have made it problematic for >> many years. > > This is not even trivially true. SSE requires no change in the ABI > to support: > it is purely convenience to start with a known 16-byte alignment: an > andb and a > register save/restore fixes the problem completely, without > abandoning the > standard. I believe gcc still abides by this "problematic for many > years" > standard in all respects except stack alignment, which is a trivial > problem to > solve and still abide by the standard. So, you abandoned standard > compliance > to solve a minor irritant, that you yourself have fixed in the new > 4.4 series. > From 4.4 on, you broke the standard for no gain at all, since you > have now > added the minor complexity of manually aligning the stack anyway. > > Of course the standard seems outdated to us: it is supporting an > architecture > that is decades old, and that is the strength of it. If you want > the shiny new > stuff, you go to x86-64. > > > -- > > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38496 > -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38496
