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 41 matching lines @@
 DECLARE_FLAG(bool, verify_compiler);
 DECLARE_FLAG(bool, compiler_stats);
 
 #define TRACE_INLINING(statement)                                              \
   do {                                                                         \
     if (FLAG_trace_inlining) statement;                                        \
   } while (false)
 
 
 // Test if a call is recursive by looking in the deoptimization environment.
-static bool IsCallRecursive(const Function& function, Definition* call) {
+static bool IsCallRecursive(const Code& code, Definition* call) {
   Environment* env = call->env();
   while (env != NULL) {
-    if (function.raw() == env->function().raw()) return true;
+    if (code.raw() == env->code().raw()) {
+      return true;
+    }
     env = env->outer();
   }
   return false;
 }
 
 
 // Helper to create a parameter stub from an actual argument.
 static Definition* CreateParameterStub(intptr_t i,
                                        Value* argument,
                                        FlowGraph* graph) {
@@ skipping 351 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;
     }
 
+    // Make a handle for the unoptimized code so that it is not disconnected
+    // from the function while we are trying to inline it.
+    const Code& unoptimized_code = Code::Handle(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 12 matching lines @@
                                "call sites: %" Pd ", "
                                "const args: %" Pd "\n",
                                function.optimized_instruction_count(),
                                function.optimized_call_site_count(),
                                constant_arguments));
       return false;
     }
 
     // Abort if this is a recursive occurrence.
     Definition* call = call_data->call;
-    if (!FLAG_inline_recursive && IsCallRecursive(function, call)) {
+    if (!FLAG_inline_recursive && IsCallRecursive(unoptimized_code, call)) {
       function.set_is_inlinable(false);
       TRACE_INLINING(OS::Print("     Bailout: recursive function\n"));
       return false;
     }
 
     Isolate* isolate = Isolate::Current();
     // Save and clear deopt id.
     const intptr_t prev_deopt_id = isolate->deopt_id();
     isolate->set_deopt_id(0);
     // Install bailout jump.
     LongJump* base = isolate->long_jump_base();
     LongJump jump;
     isolate->set_long_jump_base(&jump);
     if (setjmp(*jump.Set()) == 0) {
       // Parse the callee function.
       bool in_cache;
       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 Handle 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 102 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;
 
       // When inlined, we add the guarded fields of the callee to the caller's
       // list of guarded fields.
       for (intptr_t i = 0; i < callee_graph->guarded_fields()->length(); ++i) {
         FlowGraph::AddToGuardedFields(caller_graph_->guarded_fields(),
                                       (*callee_graph->guarded_fields())[i]);
       }
 
+      // We allocate a ZoneHandle for the unoptimized code so that it cannot be
+      // disconnected from its function during the rest of compilation.
+      Code::ZoneHandle(unoptimized_code.raw());
       TRACE_INLINING(OS::Print("     Success\n"));
       return true;
     } else {
       Error& error = Error::Handle();
       error = isolate->object_store()->sticky_error();
       isolate->object_store()->clear_sticky_error();
       isolate->set_long_jump_base(base);
       isolate->set_deopt_id(prev_deopt_id);
       TRACE_INLINING(OS::Print("     Bailout: %s\n", error.ToErrorCString()));
       return false;
@@ skipping 821 matching lines @@
         OS::Print("After Inlining of %s\n", flow_graph_->
                   parsed_function().function().ToFullyQualifiedCString());
         FlowGraphPrinter printer(*flow_graph_);
         printer.PrintBlocks();
       }
     }
   }
 }
 
 }  // namespace dart