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Re: [PATCH] Optimize MIPS memcpy
On 21/09/2012, at 6:38 AM, Steve Ellcey wrote:
> On Thu, 2012-09-20 at 21:05 +1200, Maxim Kuvyrkov wrote:
>
>> What testing was done for this patch, does it pass glibc testsuite?
>>
>> I have a benchmark that exercises various string and mem* routines failing with it.
>>
>> Thank you,
>>
>> --
>> Maxim Kuvyrkov
>> CodeSourcery / Mentor Graphics
>
> Is the benchmark anything you can share? I ran the glibc testsuite and
> got some failures but I don't think they are due to the new memcpy. I
> am going back now and running the glibc testsuite with no changes to get
> a baseline so I can verify that. Hopefully I will have an answer later
> today.
>
> I ran some other tests like the gcc testsuite using a glibc with this
> change in it and that didn't have any problems and there is the one I
> sent to the list
> http://sourceware.org/ml/libc-ports/2012-09/msg00007.html that also ran
> with no problems.
As I mentioned in a different email, I can't share the benchmark, but I think I've got a testcase of sorts for you to investigate. It appears your memcpy clobbers a couple of bytes just before DEST in certain cases.
In particular when ABI=N32, DEST=0x10060008, SRC=0x1002c088, N=0x172 it clobbers DEST[-1] and DEST[-2] bytes.
--
Maxim Kuvyrkov
CodeSourcery / Mentor Graphics