[PATCH] D118534: [X86] Update generic process model to x86-64-v3 to match with GCC

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

In D118534#3281811 <https://reviews.llvm.org/D118534#3281811>, @lebedev.ri wrote:

> In D118534#3281771 <https://reviews.llvm.org/D118534#3281771>, @spatel wrote:
>
>> The default tuning came up in the context of bsf vs. tzcnt here:
>> D117912 <https://reviews.llvm.org/D117912>
>> So I wasn't expecting a bump in default tuning yet, but I think it's great.
>>
>> But I agree that this change may cause a lot of surprises, so users need to be given notice (add a line to the clang release notes?) and wait for the 14.0 branch to be created.
>>
>> Should we have a test file that intentionally shows codegen changes as this setting gets updated?
>
> Please note that there is a *very* important difference between `-march=` and `-mtune=`:
>
> - `-march=` means: no, please, i really only intend to run this code on this specific CPU, so feel free to use all of the ISA available, and schedule for this cCPU too.
> - while `-mtune=` means: i want to be able to run the code on earlier processors, but do schedule for this CPU though.
>
> So this change really shouldn't affect available instruction sets.

Ah, thanks for explaining. I confused the settings. So it's still a small bit of progress, just not as much as I thought.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D118534/new/

https://reviews.llvm.org/D118534