Chandler Carruth a48e3ffca5 [PM/LoopUnswitch] Add partial non-trivial unswitching for invariant ... conditions feeding a chain of `and`s or `or`s for a branch. Much like with full non-trivial unswitching, we rely on the pass manager to handle iterating until all of the profitable unswitches have been done. This is to allow other more profitable unswitches to fire on any of the cloned, simpler versions of the loop if viable. Threading the partial unswiching through the non-trivial unswitching logic motivated some minor refactorings. If those are too disruptive to make it reasonable to review this patch, I can separate them out, but it'll be somewhat timeconsuming so I wanted to send it for initial review as-is. Feel free to tell me whether it warrants pulling apart. I've tried to re-use (and factor out) logic form the partial trivial unswitching, but not as much could be shared as I had haped. Still, this wasn't as bad as I naively expected. Some basic testing is added, but I probably need more. Suggestions for things you'd like to see tested more than welcome. One thing I'd like to do is add some testing that when we schedule this with loop-instsimplify it effectively cleans up the cruft created. Last but not least, this uncovered a bug that has been in loop cloning the entire time for non-trivial unswitching. Specifically, we didn't correctly add the outer-most cloned loop to the list of cloned loops. This meant that LCSSA wouldn't be updated for it hypothetically, and more significantly that we would never visit it in the loop pass manager. I noticed this while checking loop-instsimplify by hand. I'll try to separate this bugfix out into its own patch with a more focused test. But it is just one line, so shouldn't significantly confuse the review here. After this patch, the only missing "feature" in this unswitch I'm aware of us non-trivial unswitching of switches. I'll try implementing *full* non-trivial unswitching of switches (which is at least a sound thing to implement), but *partial* non-trivial unswitching of switches is something I don't see any sound and principled way to implement. I also have no interesting test cases for the latter, so I'm not really worried. The rest of the things that need to be ported are bug-fixes and more narrow / targeted support for specific issues. Differential Revision: https://reviews.llvm.org/D47522 llvm-svn: 335203		2018-06-21 06:14:03 +00:00
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llvm	[PM/LoopUnswitch] Add partial non-trivial unswitching for invariant	2018-06-21 06:14:03 +00:00
llvm-c	[DebugInfo] Refactoring DIType::setFlags to DIType::cloneWithFlags, NFC	2018-06-01 23:15:09 +00:00