Revert r253253 and r253126: "Don't recompute LCSSA after loop-unrolling when possible."

The change exposed a bug in IndVarSimplify (PR25578), which led to a
failure (PR25538). When the bug is fixed, this patch can be reapplied.

The tests are kept in tree, as they're useful anyway, and will not break
with this revert.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253596 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed