Reland r341269. Previous commit has no deterministic order between two GEPs
that share the same base GV and have the same offset but are of different types.
Now we choose the one with less number of indices as "smaller".
Reverting commit, r341365:
Revert r341269: [Constant Hoisting] Hoisting Constant GEP Expressions
One of the tests is failing 50% of the time when expensive checks are
enabled. Not sure how deep the problem is so just reverting while the
author can investigate so that the bots stop repeatedly failing and
blaming things incorrectly. Will respond with details on the original
commit.
Original commit, r341269:
[Constant Hoisting] Hoisting Constant GEP Expressions
Leverage existing logic in constant hoisting pass to transform constant GEP
expressions sharing the same base global variable. Multi-dimensional GEPs are
rewritten into single-dimensional GEPs.
Differential Revision: https://reviews.llvm.org/D51396