This patch adds support for detecting outer loops with irreducible control
flow in LV. Current detection uses SCCs and only works for innermost loops.
This patch adds a utility function that works on any CFG, given its RPO
traversal and its LoopInfoBase. This function is a generalization
of isIrreducibleCFG from lib/CodeGen/ShrinkWrap.cpp. The code in
lib/CodeGen/ShrinkWrap.cpp is also updated to use the new generic utility
function.
Patch by Diego Caballero <diego.caballero@intel.com>
Differential Revision: https://reviews.llvm.org/D40874
llvm-svn: 326568
515acd64fd