Compute the loop nest depth of each CfgNode and weight Variables by it.

src/IceClFlags.cpp

Index: src/IceClFlags.cpp
diff --git a/src/IceClFlags.cpp b/src/IceClFlags.cpp
index fea785d05190e32e2c9c7a1311f5531e30a481d1..60117fd0665bed5c42f77ef224cf2c1d29ad80e0 100644
--- a/src/IceClFlags.cpp
+++ b/src/IceClFlags.cpp
@@ -234,6 +234,7 @@ cl::list<Ice::VerboseItem> VerboseList(
         clEnumValN(Ice::IceV_Random, "random", "Randomization details"),
         clEnumValN(Ice::IceV_Folding, "fold", "Instruction folding details"),
         clEnumValN(Ice::IceV_RMW, "rmw", "ReadModifyWrite optimization"),
+        clEnumValN(Ice::IceV_Loop, "loop", "Loop nest depth analysis"),
         clEnumValN(Ice::IceV_All, "all", "Use all verbose options"),
         clEnumValN(Ice::IceV_Most, "most",
                    "Use all verbose options except 'regalloc'"),