Some more questions about Cmm pipeline

[Jan Stolarek]

Hi Simon,

I have two questions about the Cmm pipeline:

1. I implemented a pass that replaces tail calls with a copy of the entry block we're calling to. This is slightly extended version of loopification which will hopefully enable further optimisations. Then I noticed that loopification pass used to be implemented (cmm/CmmOpt.hs, line 418) but was commented out (d92bd17ffd8715f77fd49de0fed6e39c8d0ec28b). There's also a comment: "XXX: revisit if we actually want to do this". What was the motivation for removing loopification? Is there a reason why we might not want to do it?

2. There is a module cmm/CmmRewriteAssignments.hs, which is not used at the moment. What was the motivation for disabling that pass?

Janek