[xproto: PATCH] Xmd.h: amd64-x32 ABI defines sizeof(long) == sizeof (void*) == 4

Sergei Trofimovich slyich at gmail.com
Tue Dec 20 13:09:49 PST 2011

> On 12/20/11 12:26, Sergei Trofimovich wrote:
> > What would you prefer?
> I'd prefer not supporting broken hacks pretending to be new ABI models.
> Is there any real benefit to "AMD64-x32" over simply x86-32

Whole AMD64 ISA is accessible: twice as much registers (including xmm/ymm),
instruction extensions available only in "long mode".

It helps help codecs embedded into browsers and players.
C calling convention uses registers (first six integer parameters go to registers)
which reduces stack memory traffic.

Quite nice comparing to what we have in ia32.

> or AMD64 for X applications?

Pointer memory footprint is on ia32 level. Saves Dcache and RAM for huge programs
with large amount of references (like firefox and KDE).


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