Enable lazy compilation for non-trivial outer contexts.

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2165 matching lines @@
 
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, target, 0);
   Handle<Object> code = args.at<Object>(1);
 
   if (code->IsNull()) return *target;
   RUNTIME_ASSERT(code->IsJSFunction());
   Handle<JSFunction> source = Handle<JSFunction>::cast(code);
   Handle<SharedFunctionInfo> target_shared(target->shared());
   Handle<SharedFunctionInfo> source_shared(source->shared());
 
-  if (!source->is_compiled() &&
-      !JSFunction::CompileLazy(source, KEEP_EXCEPTION)) {
+  if (!JSFunction::EnsureCompiled(source, KEEP_EXCEPTION)) {
     return Failure::Exception();
   }
 
   // Set the code, scope info, formal parameter count, and the length
   // of the target shared function info.  Set the source code of the
   // target function to undefined.  SetCode is only used for built-in
   // constructors like String, Array, and Object, and some web code
   // doesn't like seeing source code for constructors.
   target_shared->set_code(source_shared->code());
   target_shared->set_scope_info(source_shared->scope_info());
@@ skipping 2650 matching lines @@
   }
   return isolate->heap()->true_value();
 }
 
 
 // Set one shot breakpoints for the callback function that is passed to a
 // built-in function such as Array.forEach to enable stepping into the callback.
 RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugPrepareStepInIfStepping) {
   Debug* debug = isolate->debug();
   if (!debug->IsStepping()) return NULL;
-  CONVERT_ARG_CHECKED(Object, callback, 0);
+  CONVERT_ARG_HANDLE_CHECKED(JSFunction, callback, 0);
   HandleScope scope(isolate);
-  Handle<SharedFunctionInfo> shared_info(JSFunction::cast(callback)->shared());
   // When leaving the callback, step out has been activated, but not performed
   // if we do not leave the builtin.  To be able to step into the callback
   // again, we need to clear the step out at this point.
   debug->ClearStepOut();
-  debug->FloodWithOneShot(shared_info);
+  debug->FloodWithOneShot(callback);
   return NULL;
 }
 
 
 // Set a local property, even if it is READ_ONLY.  If the property does not
 // exist, it will be added with attributes NONE.
 RUNTIME_FUNCTION(MaybeObject*, Runtime_IgnoreAttributesAndSetProperty) {
   NoHandleAllocation ha;
   RUNTIME_ASSERT(args.length() == 3 || args.length() == 4);
   CONVERT_ARG_CHECKED(JSObject, object, 0);
@@ skipping 3257 matching lines @@
       // the shared part of the function. Since the receiver is
       // ignored anyway, we use the global object as the receiver
       // instead of a new JSFunction object. This way, errors are
       // reported the same way whether or not 'Function' is called
       // using 'new'.
       return isolate->context()->global();
     }
   }
 
   // The function should be compiled for the optimization hints to be
-  // available. We cannot use EnsureCompiled because that forces a
-  // compilation through the shared function info which makes it
-  // impossible for us to optimize.
-  if (!function->is_compiled()) {
-    JSFunction::CompileLazy(function, CLEAR_EXCEPTION);
-  }
+  // available.
+  JSFunction::EnsureCompiled(function, CLEAR_EXCEPTION);
 
   Handle<SharedFunctionInfo> shared(function->shared(), isolate);
   if (!function->has_initial_map() &&
       shared->IsInobjectSlackTrackingInProgress()) {
     // The tracking is already in progress for another function. We can only
     // track one initial_map at a time, so we force the completion before the
     // function is called as a constructor for the first time.
     shared->CompleteInobjectSlackTracking();
   }
 
@@ skipping 2989 matching lines @@
     Handle<SharedFunctionInfo> shared_info(function_->shared());
     Handle<ScopeInfo> scope_info(shared_info->scope_info());
     if (shared_info->script() == isolate->heap()->undefined_value()) {
       while (context_->closure() == *function_) {
         context_ = Handle<Context>(context_->previous(), isolate_);
       }
       return;
     }
 
     // Get the debug info (create it if it does not exist).
-    if (!isolate->debug()->EnsureDebugInfo(shared_info)) {
+    if (!isolate->debug()->EnsureDebugInfo(shared_info, function_)) {
       // Return if ensuring debug info failed.
       return;
     }
     Handle<DebugInfo> debug_info = Debug::GetDebugInfo(shared_info);
 
     // Find the break point where execution has stopped.
     BreakLocationIterator break_location_iterator(debug_info,
                                                   ALL_BREAK_LOCATIONS);
     break_location_iterator.FindBreakLocationFromAddress(frame->pc());
     if (break_location_iterator.IsExit()) {
@@ skipping 502 matching lines @@
   Handle<SharedFunctionInfo> shared(fun->shared());
   // Find the number of break points
   Handle<Object> break_locations = Debug::GetSourceBreakLocations(shared);
   if (break_locations->IsUndefined()) return isolate->heap()->undefined_value();
   // Return array as JS array
   return *isolate->factory()->NewJSArrayWithElements(
       Handle<FixedArray>::cast(break_locations));
 }
 
 
-// Set a break point in a function
-// args[0]: function
-// args[1]: number: break source position (within the function source)
-// args[2]: number: break point object
-RUNTIME_FUNCTION(MaybeObject*, Runtime_SetFunctionBreakPoint) {
-  HandleScope scope(isolate);
-  ASSERT(args.length() == 3);
-  CONVERT_ARG_HANDLE_CHECKED(JSFunction, fun, 0);
-  Handle<SharedFunctionInfo> shared(fun->shared());
-  CONVERT_NUMBER_CHECKED(int32_t, source_position, Int32, args[1]);
-  RUNTIME_ASSERT(source_position >= 0);
-  Handle<Object> break_point_object_arg = args.at<Object>(2);
-
-  // Set break point.
-  isolate->debug()->SetBreakPoint(shared, break_point_object_arg,
-                                  &source_position);
-
-  return Smi::FromInt(source_position);
-}
-
-
 Object* Runtime::FindSharedFunctionInfoInScript(Isolate* isolate,
                                                 Handle<Script> script,
                                                 int position) {
+  // The below fix-point iteration depends on all functions that cannot be
+  // compiled lazily without a context to not be compiled at all. Compilation
+  // will be triggered at points where we do not need a context.
+  isolate->debug()->PrepareForBreakPoints();
+
   // Iterate the heap looking for SharedFunctionInfo generated from the
   // script. The inner most SharedFunctionInfo containing the source position
   // for the requested break point is found.
   // NOTE: This might require several heap iterations. If the SharedFunctionInfo
   // which is found is not compiled it is compiled and the heap is iterated
   // again as the compilation might create inner functions from the newly
   // compiled function and the actual requested break point might be in one of
   // these functions.
   bool done = false;
   // The current candidate for the source position:
   int target_start_position = RelocInfo::kNoPosition;
+  Handle<JSFunction> target_function;
   Handle<SharedFunctionInfo> target;
   while (!done) {
     { // Extra scope for iterator and no-allocation.
       isolate->heap()->EnsureHeapIsIterable();
       AssertNoAllocation no_alloc_during_heap_iteration;
       HeapIterator iterator;
       for (HeapObject* obj = iterator.next();
            obj != NULL; obj = iterator.next()) {
-        if (obj->IsSharedFunctionInfo()) {
-          Handle<SharedFunctionInfo> shared(SharedFunctionInfo::cast(obj));
-          if (shared->script() == *script) {
-            // If the SharedFunctionInfo found has the requested script data and
-            // contains the source position it is a candidate.
-            int start_position = shared->function_token_position();
-            if (start_position == RelocInfo::kNoPosition) {
-              start_position = shared->start_position();
-            }
-            if (start_position <= position &&
-                position <= shared->end_position()) {
-              // If there is no candidate or this function is within the current
-              // candidate this is the new candidate.
-              if (target.is_null()) {
-                target_start_position = start_position;
-                target = shared;
-              } else {
-                if (target_start_position == start_position &&
-                    shared->end_position() == target->end_position()) {
-                    // If a top-level function contain only one function
-                    // declartion the source for the top-level and the
-                    // function is the same. In that case prefer the non
-                    // top-level function.
-                  if (!shared->is_toplevel()) {
-                    target_start_position = start_position;
-                    target = shared;
-                  }
-                } else if (target_start_position <= start_position &&
-                           shared->end_position() <= target->end_position()) {
-                  // This containment check includes equality as a function
-                  // inside a top-level function can share either start or end
-                  // position with the top-level function.
+        bool found_next_candidate = false;
+        Handle<JSFunction> function;
+        Handle<SharedFunctionInfo> shared;
+        if (obj->IsJSFunction()) {
+          function = Handle<JSFunction>(JSFunction::cast(obj));
+          shared = Handle<SharedFunctionInfo>(function->shared());
+          ASSERT(shared->allows_lazy_compilation() || shared->is_compiled());
+          found_next_candidate = true;
+        } else if (obj->IsSharedFunctionInfo()) {
+          shared = Handle<SharedFunctionInfo>(SharedFunctionInfo::cast(obj));
+          // Skip functions that we cannot compile lazily without a context,
+          // which is not available here, because there is no closure.
+          found_next_candidate = shared->is_compiled() ||
+              shared->allows_lazy_compilation_without_context();
+        }
+        if (!found_next_candidate) continue;
+        if (shared->script() == *script) {
+          // If the SharedFunctionInfo found has the requested script data and
+          // contains the source position it is a candidate.
+          int start_position = shared->function_token_position();
+          if (start_position == RelocInfo::kNoPosition) {
+            start_position = shared->start_position();
+          }
+          if (start_position <= position &&
+              position <= shared->end_position()) {
+            // If there is no candidate or this function is within the current
+            // candidate this is the new candidate.
+            if (target.is_null()) {
+              target_start_position = start_position;
+              target_function = function;
+              target = shared;
+            } else {
+              if (target_start_position == start_position &&
+                  shared->end_position() == target->end_position()) {
+                // If a top-level function contains only one function
+                // declaration the source for the top-level and the function
+                // is the same. In that case prefer the non top-level function.
+                if (!shared->is_toplevel()) {
                   target_start_position = start_position;
+                  target_function = function;
                   target = shared;
                 }
+              } else if (target_start_position <= start_position &&
+                         shared->end_position() <= target->end_position()) {
+                // This containment check includes equality as a function
+                // inside a top-level function can share either start or end
+                // position with the top-level function.
+                target_start_position = start_position;
+                target_function = function;
+                target = shared;
               }
             }
           }
         }
       }  // End for loop.
-    }  // End No allocation scope.
+    }  // End no-allocation scope.
 
     if (target.is_null()) {
       return isolate->heap()->undefined_value();
     }
 
-    // If the candidate found is compiled we are done. NOTE: when lazy
-    // compilation of inner functions is introduced some additional checking
-    // needs to be done here to compile inner functions.
+    // If the candidate found is compiled we are done.
     done = target->is_compiled();
     if (!done) {
-      // If the candidate is not compiled compile it to reveal any inner
-      // functions which might contain the requested source position.
-      SharedFunctionInfo::CompileLazy(target, KEEP_EXCEPTION);
+      // If the candidate is not compiled, compile it to reveal any inner
+      // functions which might contain the requested source position. This
+      // will compile all inner functions that cannot be compiled without a
+      // context, because Compiler::BuildFunctionInfo checks whether the
+      // debugger is active.
+      if (target_function.is_null()) {
+        SharedFunctionInfo::CompileLazy(target, KEEP_EXCEPTION);
+      } else {
+        JSFunction::CompileLazy(target_function, KEEP_EXCEPTION);
+      }
     }
   }  // End while loop.
 
   return *target;
 }
 
 
+// Set a break point in a function.
+// args[0]: function
+// args[1]: number: break source position (within the function source)
+// args[2]: number: break point object
+RUNTIME_FUNCTION(MaybeObject*, Runtime_SetFunctionBreakPoint) {
+  HandleScope scope(isolate);
+  ASSERT(args.length() == 3);
+  CONVERT_ARG_HANDLE_CHECKED(JSFunction, function, 0);
+  CONVERT_NUMBER_CHECKED(int32_t, source_position, Int32, args[1]);
+  RUNTIME_ASSERT(source_position >= 0);
+  Handle<Object> break_point_object_arg = args.at<Object>(2);
+
+  // Set break point.
+  isolate->debug()->SetBreakPoint(function, break_point_object_arg,
+                                  &source_position);
+
+  return Smi::FromInt(source_position);
+}
+
+
 // Changes the state of a break point in a script and returns source position
 // where break point was set. NOTE: Regarding performance see the NOTE for
 // GetScriptFromScriptData.
 // args[0]: script to set break point in
 // args[1]: number: break source position (within the script source)
 // args[2]: number: break point object
 RUNTIME_FUNCTION(MaybeObject*, Runtime_SetScriptBreakPoint) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 3);
   CONVERT_ARG_HANDLE_CHECKED(JSValue, wrapper, 0);
   CONVERT_NUMBER_CHECKED(int32_t, source_position, Int32, args[1]);
   RUNTIME_ASSERT(source_position >= 0);
   Handle<Object> break_point_object_arg = args.at<Object>(2);
 
   // Get the script from the script wrapper.
   RUNTIME_ASSERT(wrapper->value()->IsScript());
   Handle<Script> script(Script::cast(wrapper->value()));
 
-  Object* result = Runtime::FindSharedFunctionInfoInScript(
-      isolate, script, source_position);
-  if (!result->IsUndefined()) {
-    Handle<SharedFunctionInfo> shared(SharedFunctionInfo::cast(result));
-    // Find position within function. The script position might be before the
-    // source position of the first function.
-    int position;
-    if (shared->start_position() > source_position) {
-      position = 0;
-    } else {
-      position = source_position - shared->start_position();
-    }
-    isolate->debug()->SetBreakPoint(shared, break_point_object_arg, &position);
-    position += shared->start_position();
-    return Smi::FromInt(position);
+  // Set break point.
+  if (!isolate->debug()->SetBreakPointForScript(script, break_point_object_arg,
+                                                &source_position)) {
+    return  isolate->heap()->undefined_value();
   }
-  return  isolate->heap()->undefined_value();
+
+  return Smi::FromInt(source_position);
 }
 
 
 // Clear a break point
 // args[0]: number: break point object
 RUNTIME_FUNCTION(MaybeObject*, Runtime_ClearBreakPoint) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 1);
   Handle<Object> break_point_object_arg = args.at<Object>(0);
 
@@ skipping 703 matching lines @@
   return isolate->heap()->undefined_value();
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugDisassembleFunction) {
 #ifdef DEBUG
   HandleScope scope(isolate);
   ASSERT(args.length() == 1);
   // Get the function and make sure it is compiled.
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, func, 0);
-  if (!JSFunction::CompileLazy(func, KEEP_EXCEPTION)) {
+  if (!JSFunction::EnsureCompiled(func, KEEP_EXCEPTION)) {
     return Failure::Exception();
   }
   func->code()->PrintLn();
 #endif  // DEBUG
   return isolate->heap()->undefined_value();
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugDisassembleConstructor) {
 #ifdef DEBUG
   HandleScope scope(isolate);
   ASSERT(args.length() == 1);
   // Get the function and make sure it is compiled.
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, func, 0);
-  if (!JSFunction::CompileLazy(func, KEEP_EXCEPTION)) {
+  if (!JSFunction::EnsureCompiled(func, KEEP_EXCEPTION)) {
     return Failure::Exception();
   }
   func->shared()->construct_stub()->PrintLn();
 #endif  // DEBUG
   return isolate->heap()->undefined_value();
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_FunctionGetInferredName) {
   NoHandleAllocation ha;
@@ skipping 1026 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal