[PATCH] D58045: [IndVars] Fix corner case with unreachable Phi inputs. PR40454

Max Kazantsev via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Mon Feb 11 04:04:47 PST 2019

mkazantsev created this revision.
mkazantsev added reviewers: cszide, spatel, andreadb, sanjoy, skatkov.

Logic in `getInsertPointForUses` doesn't account for a corner case when `Def` only
comes to a Phi user from unreachable blocks. In this case, the incoming value may
be arbitrary (and not even available in the input block) and break the loop-related
invariants that are asserted below.

In fact, if we encounter this situation, no IR modification is needed. This Phi will be
simplified away with nearest cleanup.



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