[LCSSA] Implement linear algorithm for the isRecursivelyLCSSAForm

For each block check that it doesn't have any uses outside of it's innermost loop.

Differential Revision: https://reviews.llvm.org/D25364



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@283877 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed