[LoopGuardWidening] Split out a loop pass version of GuardWidening
The idea is to have a pass which performs the same transformation as GuardWidening, but can be run within a loop pass manager without disrupting the pass manager structure. As demonstrated by the test case, this doesn't quite get there because of issues with post dom, but it gives a good step in the right direction. the motivation is purely to reduce compile time since we can now preserve locality during the loop walk.
This patch only includes a legacy pass. A follow up will add a new style pass as well.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@331060 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed