Add EP_CGSCCOptimizerLate extension point to PassManagerBuilder

The EP_CGSCCOptimizerLate extension point allows adding CallGraphSCC
passes at the end of the main CallGraphSCC passes and before any
function simplification passes run by CGPassManager.

Patch by Gor Nishanov!

Differential Revision: https://reviews.llvm.org/D22897

llvm-svn: 276953

llvm/include/llvm/Transforms/IPO/PassManagerBuilder.h

@@ -100,6 +100,11 @@ public:
     /// peephole optimizations similar to the instruction combiner. These passes
     /// will be inserted after each instance of the instruction combiner pass.
     EP_Peephole,
+
+    /// EP_CGSCCOptimizerLate - This extension point allows adding CallGraphSCC
+    /// passes at the end of the main CallGraphSCC passes and before any
+    /// function simplification passes run by CGPassManager.
+    EP_CGSCCOptimizerLate,
   };
 
   /// The Optimization Level - Specify the basic optimization level.

llvm/lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -440,6 +440,7 @@ void PassManagerBuilder::populateModulePassManager(
   if (OptLevel > 2)
     MPM.add(createArgumentPromotionPass()); // Scalarize uninlined fn args
 
+  addExtensionsToPM(EP_CGSCCOptimizerLate, MPM);
   addFunctionSimplificationPasses(MPM);
 
   // FIXME: This is a HACK! The inliner pass above implicitly creates a CGSCC