[PATCH] D36704: [CodeGen] Improve the consistency of instruction fusion

[Florian Hahn via Phabricator via llvm-commits]

fhahn added a comment.

In https://reviews.llvm.org/D36704#843847, @evandro wrote:

> There may be situations when the SecondSU has a couple of predecessors, but only one of them makes a pair and becomes the FirstSU.  I think that if one chooses the scheduler to be only either top-down or bottom-up, this change would keep the results consistent.


Yep that's a good call I think.

> Control dependencies are weaker than data dependencies and, since I could not find different results, it seemed sensible to trim the graph.

OK. IIRC only adding artificial edges for data dependencies was something I tried in my initial patch, but there were some cases where the results are worse. I'll try to chase this up tomorrow.


https://reviews.llvm.org/D36704