Fixes a couple problems with GC of unoptimized code.

runtime/vm/flow_graph_inliner.cc

Index: runtime/vm/flow_graph_inliner.cc
===================================================================
--- runtime/vm/flow_graph_inliner.cc	(revision 30197)
+++ runtime/vm/flow_graph_inliner.cc	(working copy)
@@ -486,6 +486,10 @@
       return false;
     }
 
+    // Allocate a ZoneHandle so that the unoptimized code is not collected
+    // while we are trying to inline its function.
+    const Code& unoptimized_code =

[Ivan Posva, 2013/11/16 00:06:21]

We should probably keep the code in a local handle until we are certain that we
are going to inline and then we can stuff the unoptimized code into the zone
handle just before returning true.

[zra, 2013/11/18 18:54:33]

Done.

+        Code::ZoneHandle(function.unoptimized_code());
     // Abort if the inlinable bit on the function is low.
     if (!function.IsInlineable()) {
       TRACE_INLINING(OS::Print("     Bailout: not inlinable\n"));
@@ -545,12 +549,12 @@
 
       // Load IC data for the callee.
       Array& ic_data_array = Array::Handle();
-      if (function.HasCode()) {
-        const Code& unoptimized_code =
-            Code::Handle(function.unoptimized_code());
-        ic_data_array = unoptimized_code.ExtractTypeFeedbackArray();
-      }
 
+      // IsInlineable above checked HasCode. Creating a ZoneHandle for the code
+      // should have kept GC from detaching, but let's assert just to make sure.
+      ASSERT(function.HasCode());
+      ic_data_array = unoptimized_code.ExtractTypeFeedbackArray();
+
       // Build the callee graph.
       InlineExitCollector* exit_collector =
           new InlineExitCollector(caller_graph_, call);
@@ -667,7 +671,9 @@
       collected_call_sites_->FindCallSites(callee_graph, inlining_depth_);
 
       // Add the function to the cache.
-      if (!in_cache) function_cache_.Add(parsed_function);
+      if (!in_cache) {
+        function_cache_.Add(parsed_function);
+      }
 
       // Build succeeded so we restore the bailout jump.
       inlined_ = true;