More profiler driven tweaks.

Make more code inlinable by moving to header files.
Use reserve on std::vectors to avoid reallocation.

Change-Id: I1bf67d32dd58ff5c06dec73a247fadc3de593e91
diff --git a/src/compiler/dex/mir_graph.cc b/src/compiler/dex/mir_graph.cc
index 6154eec..fe0f0c7 100644
--- a/src/compiler/dex/mir_graph.cc
+++ b/src/compiler/dex/mir_graph.cc
@@ -1037,6 +1037,9 @@
 
 std::string MIRGraph::GetSSAName(int ssa_reg)
 {
+  // TODO: This value is needed for LLVM and debugging. Currently, we compute this and then copy to
+  //       the arena. We should be smarter and just place straight into the arena, or compute the
+  //       value more lazily.
   return StringPrintf("v%d_%d", SRegToVReg(ssa_reg), GetSSASubscript(ssa_reg));
 }