Re: [PATCH 1/3] ArmPkg/CompilerIntrinsicsLib: replace memcpy and memset with C code

[Andrew Fish <afish@apple.com>]

> On Aug 11, 2016, at 2:50 PM, Cohen, Eugene <eugene@hp.com> wrote:
> 
>>> Why does memcpy performance matter?  In addition to the overall
>> memcpy stuff scattered around C code we have an instance that is
>> particularly sensitive to memcpy performance.  For DMA operations
>> when invoking double-buffering or access to portions of a buffer that
>> is common mapped (i.e. uncached on non-coherent DMA systems) the
>> impact of a non-optimized memcpy is enormous compared to the
>> optimized ones because the penalty is amplified by orders of
>> magnitude due to uncached memory access latency.
>>> 
>> 
>> That code would be using CopyMem(), no? This only serves the
>> compiler
>> generated calls, which are few since Tianocore does not allow
>> initialized locals.
> 
> I see and agree that should minimize the impact.   I guess I'll ask the naive question.  Could the BaseMemoryLib and CompilerIntrinsicsLib share the same stuff?
> 

Eugene,

I think if a CompilerIntrinsicsLib implementation consumes the BaseMemoryLib class (lists it in the INF) then I think it should just work.

Thanks,

Andrew Fish

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