Add some constantness to BranchProbabilityInfo and BlockFrequnencyInfo.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146986 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 5147b6c..36bdf38 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -454,7 +454,8 @@
                                 MachineBasicBlock* Default,
                                 MachineBasicBlock *SwitchBB);
 
-  uint32_t getEdgeWeight(MachineBasicBlock *Src, MachineBasicBlock *Dst);
+  uint32_t getEdgeWeight(const MachineBasicBlock *Src,
+                         const MachineBasicBlock *Dst) const;
   void addSuccessorWithWeight(MachineBasicBlock *Src, MachineBasicBlock *Dst,
                               uint32_t Weight = 0);
 public: