Fix for issues 6080 - pass in the Isolate's top context into the stub for invoking dart code from n…

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 18203)
+++ runtime/vm/parser.cc	(working copy)
@@ -180,6 +180,16 @@
                                scope,
                                &context_owner);
 
+  // Allocate a local variable to save the current context when we call into

[hausner, 2013/02/07 17:00:45]

Can we allocate this variable only when really needed? That would save a stack
slot in almost all activation frames, and one VarDescriptor entry in pretty much
every function object.

[siva, 2013/02/07 22:08:31]

Changed this to allocate only when needed following the expression temp model.

PTAL.

On 2013/02/07 17:00:45, hausner wrote:

+  // any closure function as the call will destroy the current context.
+  LocalVariable* context_var =
+      new LocalVariable(function().token_pos(),
+                        Symbols::SavedCurrentContextVar(),
+                        Type::ZoneHandle(Type::DynamicType()));
+  context_var->set_index(next_free_frame_index--);
+  scope->AddVariable(context_var);
+  set_saved_current_context_var(context_var);
+
   // If this function allocates context variables, but none of its enclosing
   // functions do, the context on entry is not linked as parent of the allocated
   // context but saved on entry and restored on exit as to prevent memory leaks.
@@ -5938,9 +5948,10 @@
   TRACE_PARSER("ParseTryStatement");
 
   // We create three stack slots for exceptions here:
-  // ':saved_context_var' - Used to save the context before start of the try
-  //                        block. The context register is restored from this
-  //                        slot before processing the catch block handler.
+  // ':saved_try_context_var' - Used to save the context before start of the try
+  //                            block. The context register is restored from
+  //                            this slot before processing the catch block
+  //                            handler.
   // ':exception_var' - Used to save the current exception object that was
   //                    thrown.
   // ':stacktrace_var' - Used to save the current stack trace object into which
@@ -5950,10 +5961,10 @@
   // and the stacktrace object when an exception is thrown.
   // These three implicit variables can never be captured variables.
   LocalVariable* context_var =
-      current_block_->scope->LocalLookupVariable(Symbols::SavedContextVar());
+      current_block_->scope->LocalLookupVariable(Symbols::SavedTryContextVar());
   if (context_var == NULL) {
     context_var = new LocalVariable(TokenPos(),
-                                    Symbols::SavedContextVar(),
+                                    Symbols::SavedTryContextVar(),
                                     Type::ZoneHandle(Type::DynamicType()));
     current_block_->scope->AddVariable(context_var);
   }