Minor compiler tuning

Large switch statements were getting bogged down in a linear search.
Added a map for fast lookup (which may also be useful for debug
support).

Change-Id: I00e5956ea7e98ff2c870fb2d3e299e8d4c88f598
diff --git a/src/compiler/CompilerIR.h b/src/compiler/CompilerIR.h
index 76649d5..1eb6c64 100644
--- a/src/compiler/CompilerIR.h
+++ b/src/compiler/CompilerIR.h
@@ -331,6 +331,7 @@
      bool usesFP;          // Method contains at least 1 non-move FP operation
      bool disableDataflow; // Skip dataflow analysis if possible
      std::map<unsigned int, BasicBlock*> blockMap; // findBlock lookup cache
+     std::map<unsigned int, LIR*> boundaryMap; // boundary lookup cache
 } CompilationUnit;
 
 BasicBlock* oatNewBB(BBType blockType, int blockId);