[PATCH] Use memcpy in memmove when possible

[Ondřej Bílka]

On Tue, Sep 04, 2012 at 05:17:52PM +1200, Maxim Kuvyrkov wrote:
> On 2/09/2012, at 12:51 AM, H.J. Lu wrote:
> 
> > On Sat, Sep 1, 2012 at 1:16 AM, Maxim Kuvyrkov <maxim@codesourcery.com> wrote:
> >> Several architectures, e.g., MIPS, have well-optimized memcpy implementations, which can also be used for either forward or backward direction in memmove.  This patch adds an option for ports to define MEMCPY_OK_FOR_{FWD,BWD}_MEMMOVE macros to make generic memmove use memcpy when safe to do so.
> >> 
> >> This patch speeds up forward-direction memmove on MIPS by 50%.  Tested with no regressions.
> >> 
> > 
> > If memcpy is safe for memmove, you can simply make memmove an alias of
> > memcpy in memcpy source.  Why do you need to update string/memmove.c?
> 
> Because memcpy is safe only for a particular direction of memmove in case input and output areas intersect.

Which wouldn't be problem if memcpy had flag to reverse direction.

> 
> --
> Maxim Kuvyrkov
> CodeSourcery / Mentor Graphics

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