Date: Fri, 8 Dec 2000 13:29:22 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: John Baldwin <jhb@FreeBSD.ORG> Cc: Julian Elischer <julian@elischer.org>, current@FreeBSD.ORG Subject: Re: RE: __asm help.. Message-ID: <200012082129.eB8LTMM22955@earth.backplane.com> References: <XFMail.001208104618.jhb@FreeBSD.org>
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:As long as gcc uses %ebp to address local variables and functoin parameters
:rather than %esp you should be fine. %esp will be preserved, but if %esp is
:for some odd reason used to address a variable during the C code, you are hosed.
I strongly recommend against making assumptions about GCC's use of %ebp vs
%esp... not if you want the __asm code to survive the GCC optimizer!
:Just use foo = save_intr(); disable_intr(); .. restore_intr() for now. If you
:want to save the 2 instructions so badly, then you should probably be writing
:the whole chunk in assembly. Getting it correct first and optimizing later is
:more sane than getting correctness and optimization at the same time and not
:knowing which one your bugs are coming from.
:
:John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
Yah, gotta agree there. The only thing that matters, Julian, are memory
accesses. The number of instructions you use is irrelevant.
-Matt
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