Break out WeakCodeReferences to own file in preparation to use it outside object.cc.

runtime/vm/weak_code.cc

+// Copyright (c) 2014, 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/weak_code.h"
+
+#include "platform/assert.h"
+
+#include "vm/code_generator.h"
+#include "vm/code_patcher.h"
+#include "vm/object.h"
+#include "vm/stack_frame.h"
+
+namespace dart {
+
+void WeakCodeReferences::Register(const Code& value) {
+  if (!array_.IsNull()) {
+    // Try to find and reuse cleared WeakProperty to avoid allocating new one.
+    WeakProperty& weak_property = WeakProperty::Handle();
+    for (intptr_t i = 0; i < array_.Length(); i++) {
+      weak_property ^= array_.At(i);
+      if (weak_property.key() == Code::null()) {
+        // Empty property found. Reuse it.
+        weak_property.set_key(value);
+        return;
+      }
+    }
+  }
+
+  const WeakProperty& weak_property = WeakProperty::Handle(
+      WeakProperty::New(Heap::kOld));
+  weak_property.set_key(value);
+
+  intptr_t length = array_.IsNull() ? 0 : array_.Length();
+  const Array& new_array = Array::Handle(
+      Array::Grow(array_, length + 1, Heap::kOld));
+  new_array.SetAt(length, weak_property);
+  UpdateArrayTo(new_array);
+}
+
+
+bool WeakCodeReferences::IsOptimizedCode(const Array& dependent_code,
+                                         const Code& code) {
+  if (!code.is_optimized()) {
+    return false;
+  }
+  WeakProperty& weak_property = WeakProperty::Handle();
+  for (intptr_t i = 0; i < dependent_code.Length(); i++) {
+    weak_property ^= dependent_code.At(i);
+    if (code.raw() == weak_property.key()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+
+void WeakCodeReferences::DisableCode() {
+  const Array& code_objects = Array::Handle(array_.raw());
+  if (code_objects.IsNull()) {
+    return;
+  }
+  UpdateArrayTo(Object::null_array());
+  // Disable all code on stack.
+  Code& code = Code::Handle();
+  {
+    DartFrameIterator iterator;
+    StackFrame* frame = iterator.NextFrame();
+    while (frame != NULL) {
+      code = frame->LookupDartCode();
+      if (IsOptimizedCode(code_objects, code)) {
+        ReportDeoptimization(code);
+        DeoptimizeAt(code, frame->pc());
+      }
+      frame = iterator.NextFrame();
+    }
+  }
+
+  // Switch functions that use dependent code to unoptimized code.
+  WeakProperty& weak_property = WeakProperty::Handle();
+  Object& owner = Object::Handle();
+  Function& function = Function::Handle();
+  for (intptr_t i = 0; i < code_objects.Length(); i++) {
+    weak_property ^= code_objects.At(i);
+    code ^= weak_property.key();
+    if (code.IsNull()) {
+      // Code was garbage collected already.
+      continue;
+    }
+    owner = code.owner();
+    if (owner.IsFunction()) {
+      function ^= owner.raw();
+    } else if (owner.IsClass()) {
+      Class& cls = Class::Handle();
+      cls ^= owner.raw();
+      OS::Print("Skipping code owned by class %s\n", cls.ToCString());
+      cls.SwitchAllocationStub();
+      continue;
+    } else if (owner.IsNull()) {
+      OS::Print("Skipping code owned by null: ");
+      code.Print();
+      continue;
+    }
+
+    // If function uses dependent code switch it to unoptimized.
+    if (code.is_optimized() && (function.CurrentCode() == code.raw())) {
+      ReportSwitchingCode(code);
+      function.SwitchToUnoptimizedCode();
+    } else if (function.unoptimized_code() == code.raw()) {
+      ReportSwitchingCode(code);
+      function.ClearICData();
+      // Remove the code object from the function. The next time the
+      // function is invoked, it will be compiled again.
+      function.ClearCode();
+      // Invalidate the old code object so existing references to it
+      // (from optimized code) will fail when invoked.
+      if (!CodePatcher::IsEntryPatched(code)) {
+        CodePatcher::PatchEntry(code);
+      }
+    } else {
+      // Make non-OSR code non-entrant.
+      if (code.GetEntryPatchPc() != 0) {
+        if (!CodePatcher::IsEntryPatched(code)) {
+          ReportSwitchingCode(code);
+          CodePatcher::PatchEntry(code);
+        }
+      }
+    }
+  }
+}
+
+}  // namespace dart