[PATCH] D35035: [InstCombine] Prevent memcpy generation for small data size

[Aditya Kumar via Phabricator via llvm-commits]

hiraditya added a comment.

In https://reviews.llvm.org/D35035#1284164, @jfb wrote:

> In https://reviews.llvm.org/D35035#1282236, @spatel wrote:
>
> > In https://reviews.llvm.org/D35035#1281462, @lebedev.ri wrote:
> >
> > > Not sure what is the general consensus wrt this patch, but i guess it now consistently uses bytes.
> >
> >
> > Agree - the code change looks like what I expected now.
> >
> > So:
> >
> > 1. Is @jfb objecting to this as an intermediate improvement?
>
>
> My concern is here: https://reviews.llvm.org/D35035#inline-464768
>  This uses an unrelated constant to drive optimization decisions. Create a new per-target constant.


I think the intent of this patch is to do best-effort without relying a lot on target specific constants. Will it help to have per-target constant only for mem* functions? Could that constant be used to drive other optimizations?

> 
> 
>> 2. If not, there are unanswered comments about the test diffs.
>> 3. There was also an unanswered request for the targets and size/perf improvements for this change (presumably some 32-bit target shows wins).
>> 4. Are there any updates on the perf for the ideal change (removing this expansion completely)?
> 
> I do want to see size and perf results.




Repository:
  rL LLVM

https://reviews.llvm.org/D35035