Codegen pass definition cleanup. No functionality.

Moving toward a uniform style of pass definition to allow easier target configuration.
Globally declare Pass ID.
Globally declare pass initializer.
Use INITIALIZE_PASS consistently.
Add a call to the initializer from CodeGen.cpp.
Remove redundant "createPass" functions and "getPassName" methods.

While cleaning up declarations, cleaned up comments (sorry for large diff).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150100 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineBlockPlacement.cpp b/lib/CodeGen/MachineBlockPlacement.cpp
index 638d895..63892af 100644
--- a/lib/CodeGen/MachineBlockPlacement.cpp
+++ b/lib/CodeGen/MachineBlockPlacement.cpp
@@ -224,12 +224,11 @@
     AU.addRequired<MachineLoopInfo>();
     MachineFunctionPass::getAnalysisUsage(AU);
   }
-
-  const char *getPassName() const { return "Block Placement"; }
 };
 }
 
 char MachineBlockPlacement::ID = 0;
+char &llvm::MachineBlockPlacementID = MachineBlockPlacement::ID;
 INITIALIZE_PASS_BEGIN(MachineBlockPlacement, "block-placement2",
                       "Branch Probability Basic Block Placement", false, false)
 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
@@ -238,10 +237,6 @@
 INITIALIZE_PASS_END(MachineBlockPlacement, "block-placement2",
                     "Branch Probability Basic Block Placement", false, false)
 
-FunctionPass *llvm::createMachineBlockPlacementPass() {
-  return new MachineBlockPlacement();
-}
-
 #ifndef NDEBUG
 /// \brief Helper to print the name of a MBB.
 ///
@@ -943,12 +938,11 @@
     AU.setPreservesAll();
     MachineFunctionPass::getAnalysisUsage(AU);
   }
-
-  const char *getPassName() const { return "Block Placement Stats"; }
 };
 }
 
 char MachineBlockPlacementStats::ID = 0;
+char &llvm::MachineBlockPlacementStatsID = MachineBlockPlacementStats::ID;
 INITIALIZE_PASS_BEGIN(MachineBlockPlacementStats, "block-placement-stats",
                       "Basic Block Placement Stats", false, false)
 INITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo)
@@ -956,10 +950,6 @@
 INITIALIZE_PASS_END(MachineBlockPlacementStats, "block-placement-stats",
                     "Basic Block Placement Stats", false, false)
 
-FunctionPass *llvm::createMachineBlockPlacementStatsPass() {
-  return new MachineBlockPlacementStats();
-}
-
 bool MachineBlockPlacementStats::runOnMachineFunction(MachineFunction &F) {
   // Check for single-block functions and skip them.
   if (llvm::next(F.begin()) == F.end())