arm-elf-gcc memcpy builtin?

[William A. Gatliff]

Grant:


Take a look at the one that comes with uClinux for ARM.  Ghastly code,
but it looks like it should run *really* fast.  It basically uses the
whole register file, or at least that's what I think it's doing!  :^)

Oh, it isn't endian-neutral, btw, and I don't remember which endian
sense it was written for.  That's why I was looking at it in the first
place--- I was running in the wrong one...


b.g.

On Tue, Nov 05, 2002 at 09:47:50AM -0600, Grant Edwards wrote:
> On Tue, Nov 05, 2002 at 10:10:24AM +0000, Richard Earnshaw wrote:
> 
> > > Does the ARM back end not know how to do a built-in memcpy?
> > > 
> > > $ arm-elf-gcc -v
> > > Reading specs from /usr/local/lib/gcc-lib/arm-elf/2.95.2/specs
> > > gcc version 2.95.2 19991024 (release)
> > 
> > The built-in memcpy will only be used if both the memory areas are word 
> > aligned and the transfer is less than 65 bytes.  It doesn't have to be a 
> > multiple of 4 bytes transferred.
> 
> Ah.  Most of the memcpy() calls I'm worried about have
> alignments that can't be determined at compile time, so I guess
> I'm out of luck.
> 
> The next option is to re-write the memcpy function in assembly
> and tweak every last bit of performance out of it I can.
> 
> -- 
> Grant Edwards
> grante@visi.com
> 
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-- 
Bill Gatliff
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