Extend usage of optimized JIT helpers for memcpy/memove.

[lt72]

This work item is a follow up to PR dotnet/coreclr#7198 for issue #6638.
Currently memmove and memcpy are #define'd (and #undef'ed) is a few places in the code base.
Addressing all usages of memcpy/memmove may require identifying or creating a central place where to create a definition for those methods that is eventually routed to the correct implementation.
Also, addressing all individual usages should be carried out incrementally by providing adequate performance measurements.

[gkhanna79]

@lt72 What are the next steps on this?

[lt72]

@russellhadley @RussKeldorph
I guess integrate the work Intel carried out for Clang. Addding Russ & Russell that, I believe, own such work item.

[gkhanna79]

@russellhadley @RussKeldorph What are the next steps here?

[russellhadley]

@gkhanna79 @lt72 Is this PAL work? Or is the idea that this is just in the JIT? I'm assuming that this is intended to fix the memcpy/memmove across the whole of the runtime. Gaurav is there need for a central place in the runtime for these methods to be defined?

[lt72]

@russellhadley: your assumption is correct. When I opened the work item I intended this to be a follow up to the work Intel carried out for the JIT.

[gkhanna79]

@lt72 who is working on this? Given that there has not been any progress on this, I dont believe this would be blocking for 2.0. Should this be moved out?

[lt72]

I am fine with that, but Russ & Russell should chime in since they own the execution of this work item.