Date: Tue, 30 Nov 1999 18:20:24 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Bruce Evans <bde@zeta.org.au> Cc: Marcel Moolenaar <marcel@scc.nl>, Ville-Pertti Keinonen <will@iki.fi>, current@FreeBSD.ORG Subject: Re: kernel: -mpreferred-stack-boundary=2 ?? Message-ID: <199912010220.SAA28903@apollo.backplane.com> References: <Pine.BSF.4.10.9912010603070.15878-100000@alphplex.bde.org>
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:> I guess only if you do have a PIII and are using the new instructions.
:> In most cases this has no effect whatsoever. Not counting the
:> significant code size increase.
:
:It's also useful for properly aligning doubles on the stack. I would have
:expected the most generally efficient way to align doubles and the new PIII
:obkects to be aligning the stack only in functions that have such objects
:on the stack. This requires at most one extra instruction:
:
: andl $~0xf,$esp 16-byte alignment
:
:Bruce
It would be better for GCC to force alignment only within those
procedures that need it rather then force all procedures to guarentee
alignment. Then we could have the best of both worlds.
-Matt
Matthew Dillon
<dillon@backplane.com>
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