Fixes a couple problems with GC of unoptimized code.

runtime/vm/flow_graph_inliner.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph_inliner.h"
 
 #include "vm/block_scheduler.h"
 #include "vm/compiler.h"
 #include "vm/flags.h"
 #include "vm/flow_graph.h"
@@ skipping 468 matching lines @@
                              function.ToCString(),
                              function.deoptimization_counter()));
 
     // TODO(fschneider): Enable inlining inside try-blocks.
     if (call_data->call->GetBlock()->try_index() !=
         CatchClauseNode::kInvalidTryIndex) {
       TRACE_INLINING(OS::Print("     Bailout: inside try-block\n"));
       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"));
       return false;
     }
 
     // Abort if this function has deoptimized too much.
     if (function.deoptimization_counter() >=
         FLAG_deoptimization_counter_threshold) {
       function.set_is_inlinable(false);
@@ skipping 39 matching lines @@
       ParsedFunction* parsed_function;
       {
         TimerScope timer(FLAG_compiler_stats,
                          &CompilerStats::graphinliner_parse_timer,
                          isolate);
         parsed_function = GetParsedFunction(function, &in_cache);
       }
 
       // 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);
       FlowGraphBuilder builder(parsed_function,
                                ic_data_array,
                                exit_collector,
                                Isolate::kNoDeoptId);
       builder.SetInitialBlockId(caller_graph_->max_block_id());
       FlowGraph* callee_graph;
@@ skipping 97 matching lines @@
                                  "const args: %" Pd "\n",
                                  size,
                                  call_site_count,
                                  constants_count));
         return false;
       }
 
       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;
       inlined_size_ += size;
       isolate->set_long_jump_base(base);
       isolate->set_deopt_id(prev_deopt_id);
 
       call_data->callee_graph = callee_graph;
       call_data->parameter_stubs = param_stubs;
       call_data->exit_collector = exit_collector;
@@ skipping 841 matching lines @@
         OS::Print("After Inlining of %s\n", flow_graph_->
                   parsed_function().function().ToFullyQualifiedCString());
         FlowGraphPrinter printer(*flow_graph_);
         printer.PrintBlocks();
       }
     }
   }
 }
 
 }  // namespace dart