[PATCH] D20847: BitCast infinite loop fix

[Evgeny Stupachenko via llvm-commits]

evstupac added a comment.

>   it has to have a fixpoint where it says "yeah, this is the right

> 

> form" or else you are always prone to infinite loops with phi cycles.


We can cycle only if InstCombine here adds instructions it is looking for. Otherwise patterns from Worklist will end at some point.
Unless some other InstCombine optimization adds the same pattern. However, this is generally unpredictable. To avoid such cases we can end InstCombine at some point, say if for some time Worklist only grows or stay unchanged. But that is for another patch.


Repository:
  rL LLVM

http://reviews.llvm.org/D20847