Better tracing of deoptimization (added a reason id and printing of source). Fix a bug with exces...

runtime/vm/code_generator.cc

Index: runtime/vm/code_generator.cc
===================================================================
--- runtime/vm/code_generator.cc	(revision 1585)
+++ runtime/vm/code_generator.cc	(working copy)
@@ -865,8 +865,9 @@
 // pc in the unoptimized code.
 // Since both unoptimized and optimized code have the same layout, we need only
 // to patch the pc of the Dart frame and to disable/enable appropriate code.
-DEFINE_RUNTIME_ENTRY(Deoptimize, 0) {
+DEFINE_RUNTIME_ENTRY(Deoptimize, 1) {
   ASSERT(arguments.Count() == kDeoptimizeRuntimeEntry.argument_count());
+  const Smi& deoptimization_reason_id = Smi::CheckedHandle(arguments.At(0));
   DartFrameIterator iterator;
   DartFrame* caller_frame = iterator.NextFrame();
   ASSERT(caller_frame != NULL);
@@ -883,9 +884,11 @@
   ASSERT(!descriptors.IsNull());
   // Locate node id at deoptimization point inside optimized code.
   intptr_t deopt_node_id = AstNode::kNoId;
+  intptr_t deopt_token_index = 0;
   for (int i = 0; i < descriptors.Length(); i++) {
     if (static_cast<uword>(descriptors.PC(i)) == caller_frame->pc()) {
       deopt_node_id = descriptors.NodeId(i);
+      deopt_token_index = descriptors.TokenIndex(i);
       break;
     }
   }
@@ -894,9 +897,19 @@
       unoptimized_code.GetDeoptPcAtNodeId(deopt_node_id);
   ASSERT(continue_at_pc != 0);
   if (FLAG_trace_deopt) {
-    OS::Print("Deoptimizing at pc 0x%x id %d '%s' -> continue at 0x%x \n",
-        caller_frame->pc(), deopt_node_id, function.ToFullyQualifiedCString(),
+    OS::Print("Deoptimizing (reason %d) at pc 0x%x id %d '%s' "
+        "-> continue at 0x%x \n",
+        deoptimization_reason_id.Value(),
+        caller_frame->pc(),
+        deopt_node_id,
+        function.ToFullyQualifiedCString(),
         continue_at_pc);
+    const Class& cls = Class::Handle(function.owner());
+    const Script& script = Script::Handle(cls.script());
+    intptr_t line, column;
+    script.GetTokenLocation(deopt_token_index, &line, &column);
+    OS::Print("  Line: %d Column: %d ", line, column);
+    OS::Print(">>  %s\n", String::Handle(script.GetLine(line)).ToCString());
   }
   caller_frame->set_pc(continue_at_pc);
   // Clear invocation counter so that the function gets optimized after