[PATCH] D70779: AArch64: add support for newer Apple CPUs

Tue Dec 3 10:24:18 PST 2019

ab added inline comments.

================
Comment at: llvm/lib/Target/AArch64/AArch64.td:587
+                                    "Apple A10", [
+                                    ProcAppleA7,
+                                    FeatureCRC,
----------------
ab wrote:
> t.p.northover wrote:
> > ab wrote:
> > > I'm not sure we want to reuse the features:
> > > - everything will get stuck with FeatureZCZeroingFPWorkaround, right? (but maybe we can remove features in this list?  I don't think so)
> > > - it probably becomes harder to tune later chips, but that's admittedly a theoretical problem at this point
> > > - some of the features can be generation-specific
> > Good points. It's a shame to duplicate everything (and solvable by splitting uArch stuff from the progressive features), but it does seem to be existing practice.
> > 
> > I'll rework it to be more in line with the others and add a test for the workaround you mentioned; that should have been spotted.
> Hmm, how about having these in plain top-level tablegen lists?  That lets you do `(sub)`, which might be sufficient
(I don't think that lets us have these cpu "features" though, but TBH I'm not sure what they achieve anyway)

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D70779/new/

https://reviews.llvm.org/D70779