Fixes a couple problems with GC of unoptimized code.

runtime/vm/code_generator.cc

Index: runtime/vm/code_generator.cc
===================================================================
--- runtime/vm/code_generator.cc	(revision 30197)
+++ runtime/vm/code_generator.cc	(working copy)
@@ -1343,9 +1343,13 @@
   if (FLAG_use_osr && (interrupt_bits == 0)) {
     DartFrameIterator iterator;
     StackFrame* frame = iterator.NextFrame();
-    const Function& function = Function::Handle(frame->LookupDartFunction());
+    const Code& code = Code::ZoneHandle(frame->LookupDartCode());

[srdjan, 2013/11/19 19:18:29]

Optional, as it will fail in next line: ASSERT(!code.IsNull())

[zra, 2013/11/22 17:18:54]

Done.

+    const Function& function = Function::Handle(code.function());
     ASSERT(!function.IsNull());
-    if (!CanOptimizeFunction(function, isolate)) return;
+    ASSERT(function.HasCode());

[srdjan, 2013/11/19 19:18:29]

Why does this need to be true? Is this because once optimizations kick in, we
cannot remove code? Please add brief comment, that would also cover the
ASSERT(!original_code.IsNull()).

[zra, 2013/11/22 17:18:54]

Done.

+    if (!CanOptimizeFunction(function, isolate)) {
+      return;
+    }
     intptr_t osr_id =
         Code::Handle(function.unoptimized_code()).GetDeoptIdForOsr(frame->pc());
     if (FLAG_trace_osr) {
@@ -1356,9 +1360,12 @@
     }
 
     const Code& original_code = Code::Handle(function.CurrentCode());
+    ASSERT(!original_code.IsNull());
     const Error& error =
         Error::Handle(Compiler::CompileOptimizedFunction(function, osr_id));
-    if (!error.IsNull()) Exceptions::PropagateError(error);
+    if (!error.IsNull()) {
+      Exceptions::PropagateError(error);
+    }
 
     const Code& optimized_code = Code::Handle(function.CurrentCode());
     // The current code will not be changed in the case that the compiler
@@ -1436,21 +1443,11 @@
   const Function& target_function = Function::Handle(
       caller_code.GetStaticCallTargetFunctionAt(frame->pc()));

[srdjan, 2013/11/19 19:18:29]

GetStaticCallTargetCodeAt ->target_code -> function

[zra, 2013/11/22 17:18:54]

Done.

 
-  // Check whether the code object has been detached from the target function.
-  // If it has been detached, reattach it.
-  Code& target_code = Code::Handle();
-  if (target_function.HasCode()) {
-    target_code ^= target_function.CurrentCode();
-    CodePatcher::PatchStaticCallAt(frame->pc(), caller_code,
-                                   target_code.EntryPoint());
-    caller_code.SetStaticCallTargetCodeAt(frame->pc(), target_code);
-  } else {
-    ASSERT(target_function.unoptimized_code() == Code::null());
-    target_code ^= caller_code.GetStaticCallTargetCodeAt(frame->pc());
-    ASSERT(!target_code.IsNull());
-    ASSERT(!target_code.is_optimized());
-    target_function.ReattachCode(target_code);
-  }
+  ASSERT(target_function.HasCode());
+  Code& target_code = Code::Handle(target_function.CurrentCode());
+  CodePatcher::PatchStaticCallAt(frame->pc(), caller_code,
+                                 target_code.EntryPoint());
+  caller_code.SetStaticCallTargetCodeAt(frame->pc(), target_code);
   if (FLAG_trace_patching) {
     OS::PrintErr("FixCallersTarget: patching from %#" Px " to '%s' %#" Px "\n",
         frame->pc(),
@@ -1483,7 +1480,7 @@
   const Function& function = Function::Handle(optimized_code.function());
   const Code& unoptimized_code = Code::Handle(function.unoptimized_code());
   ASSERT(!unoptimized_code.IsNull());
-  // The switch to unoptimized code may have already occured.
+  // The switch to unoptimized code may have already occurred.
   if (function.HasOptimizedCode()) {
     function.SwitchToUnoptimizedCode();
   }