jyknight requested changes to this revision.
jyknight added a comment.
This revision now requires changes to proceed.

In D74918#1885869 <https://reviews.llvm.org/D74918#1885869>, @zoecarver wrote:

> @jyknight It would probably be best if we could account for CPUs who like to 
> use aligned pairs when getting a cache line. It's probably also important 
> that we don't change the value `getCPUCacheLineSize` returns, so, if we are 
> going to account for that, we should probably update `getCPUCacheLineSize ` 
> before this patch lands.


It would be extremely unfortunate to go to all the trouble of attempting to 
return accurate results from the P0154 interfaces, and then to return an answer 
insufficient to actually achieve the performance benefit it's intended for, and 
then be unable to fix it due to ABI concerns. So, yes, I do believe that this 
issue must be decided.

Additionally, my opinion here has really not changed from a couple of years 
ago. I continue to believe it was a mistake to standardize these constexpr 
values, and that absolutely the best course of action would be to continue to 
decline to implement this part of the standard, forever. (And that GCC should 
similarly also continue to decline to implement it).

That said, the list of cacheline sizes collected in this review is still useful 
in any case, since it needs to be copied into LLVM's X86Subtarget to implement 
the backend getCacheLineSize function.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D74918/new/

https://reviews.llvm.org/D74918



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