[PATCH] D127960: [InstCombine] Push freeze through recurrence phi

[Nuno Lopes via Phabricator via llvm-commits]

nlopes added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstructionCombining.cpp:3803
+  if (StartBB->getFirstInsertionPt() == StartBB->end())
+    return nullptr; // Cannot insert into this block.
+
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aqjune wrote:
> Not sure whether this can happen; when does this condition meet?
I was also wondering about that, but I guess it may happen with malformed BBs (e.g., with just PHIs but no terminator). Unreachable BBs are allowed to be malformed in LLVM IR (which is a bit unfortunate).


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  https://reviews.llvm.org/D127960/new/

https://reviews.llvm.org/D127960