[PATCH] D43293: [SimplifyCFG] Don't remove preheaders when we need canonical loops.

Serguei Katkov via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Feb 14 19:15:52 PST 2018

skatkov added a comment.

Does it eliminate your regression?
I double the Eli's question: "What passes benefit from having SimplifyCFG keep around empty preheaders?"

Comment at: lib/Transforms/Utils/SimplifyCFG.cpp:5747
+  // introduce new backedge, so we can eliminate BB.
   bool NeedCanonicalLoop =
+      Options.NeedCanonicalLoop && LoopHeaders &&
It becomes complicated. Could you please re-write it in a more readable way?

I guess lambda with explicit ifs and possible comments may do things cleaner in terms of reading this.


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