[IndVars] Don't break dominance in `eliminateIdentitySCEV`
Summary:
After r249211, `getSCEV(X) == getSCEV(Y)` does not guarantee that X and
Y are related in the dominator tree, even if X is an operand to Y (I've
included a toy example in comments, and a real example as a test case).
This commit changes `SimplifyIndVar` to require a `DominatorTree`. I
don't think this is a problem because `ScalarEvolution` requires it
anyway.
Fixes PR25051.
Depends on D13459.
Reviewers: atrick, hfinkel
Subscribers: joker.eph, llvm-commits, sanjoy
Differential Revision: http://reviews.llvm.org/D13460
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249471 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed