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/Frontend.cc b/src/compiler/Frontend.cc
index c5692bc..2a6714f 100644
--- a/src/compiler/Frontend.cc
+++ b/src/compiler/Frontend.cc
@@ -765,6 +765,8 @@
     cUnit->numDalvikRegisters = code_item->registers_size_;
     cUnit->blockMap = std::map<unsigned int, BasicBlock*>();
     cUnit->blockMap.clear();
+    cUnit->boundaryMap = std::map<unsigned int, LIR*>();
+    cUnit->boundaryMap.clear();
     bool useMatch = compilerMethodMatch.length() != 0;
     bool match = useMatch && (compilerFlipMatch ^
         (PrettyMethod(method_idx, dex_file).find(compilerMethodMatch) != std::string::npos));