[PATCH] D50004: [PowerPC] Emit xscpsgndp instead of xxlor when copying floating point scalar registers

[Kewen Lin via Phabricator via llvm-commits]

jedilyn added a comment.

In https://reviews.llvm.org/D50004#1185697, @nemanjai wrote:

> > +1, even for Power9 XSCPSGNDP makes pipeline busy longer than XXLOR, XXLOR is still better.
>
> Can you clarify this please? Where is this information coming from? According to the UM, XXLOR takes up a whole superslice whereas XSCPSGNDP takes up a single slice so we can dispatch 2 of the former per cycle and 4 of the latter. And the "Pipe Busy Cycles" field for both is 1.


My fault, sorry, I saw the data from the wrong column "max ops per cycle". You are right, both are 1 cycle for busy pipe, XSCPSGNDP should outperform on Power9 then.


https://reviews.llvm.org/D50004