Collect type feedback for fields.

runtime/vm/object.cc

 // Copyright (c) 2012, 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/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
@@ skipping 3209 matching lines @@
 void Function::SetCode(const Code& value) const {
   StorePointer(&raw_ptr()->code_, value.raw());
   ASSERT(Function::Handle(value.function()).IsNull() ||
     (value.function() == this->raw()));
   value.set_function(*this);
 }
 
 
 void Function::SwitchToUnoptimizedCode() const {
   ASSERT(HasOptimizedCode());
+
   const Code& current_code = Code::Handle(CurrentCode());
+
+  // Optimized code object might have been actually fully produced by the
+  // intrinsifier in this case nothing has to be done. In fact an attempt to
+  // patch such code will cause crash.
+  // TODO(vegorov): if intrisifier can fully intrisify the function then we
+  // should not later try to optimize it.
+  if (PcDescriptors::Handle(current_code.pc_descriptors()).Length() == 0) {
+    return;
+  }
+
   if (FLAG_trace_disabling_optimized_code) {
     OS::Print("Disabling optimized code: '%s' entry: %#"Px"\n",
       ToFullyQualifiedCString(),
       current_code.EntryPoint());
   }
   // Patch entry of the optimized code.
   CodePatcher::PatchEntry(current_code);
   // Use previously compiled unoptimized code.
   SetCode(Code::Handle(unoptimized_code()));
   CodePatcher::RestoreEntry(Code::Handle(unoptimized_code()));
@@ skipping 1439 matching lines @@
   if (is_static) {
     result.set_value(Instance::Handle());
   } else {
     result.SetOffset(0);
   }
   result.set_is_final(is_final);
   result.set_is_const(is_const);
   result.set_owner(owner);
   result.set_token_pos(token_pos);
   result.set_has_initializer(false);
+  result.set_guarded_cid(kIllegalCid);
+  result.set_is_nullable(false);
+  result.set_dependent_code(Array::Handle());
   return result.raw();
 }
 
 
 
 RawField* Field::Clone(const Class& new_owner) const {
   Field& clone = Field::Handle();
   clone ^= Object::Clone(*this, Heap::kOld);
   const Class& owner = Class::Handle(this->owner());
   const PatchClass& clone_owner =
       PatchClass::Handle(PatchClass::New(new_owner, owner));
   clone.set_owner(clone_owner);
+  clone.set_dependent_code(Array::Handle());
   if (!clone.is_static()) {
     clone.SetOffset(0);
   }
   return clone.raw();
 }
 
 
 RawString* Field::UserVisibleName() const {
   const String& str = String::Handle(name());
   return IdentifierPrettyName(str);
 }
 
 
 const char* Field::ToCString() const {
   const char* kF0 = is_static() ? " static" : "";
   const char* kF1 = is_final() ? " final" : "";
   const char* kF2 = is_const() ? " const" : "";
   const char* kFormat = "Field <%s.%s>:%s%s%s";
   const char* field_name = String::Handle(name()).ToCString();
   const Class& cls = Class::Handle(owner());
   const char* cls_name = String::Handle(cls.Name()).ToCString();
   intptr_t len =
       OS::SNPrint(NULL, 0, kFormat, cls_name, field_name, kF0, kF1, kF2) + 1;
   char* chars = Isolate::Current()->current_zone()->Alloc<char>(len);
   OS::SNPrint(chars, len, kFormat, cls_name, field_name, kF0, kF1, kF2);
   return chars;
 }
 
 
+RawArray* Field::dependent_code() const {
+  return raw_ptr()->dependent_code_;
+}
+
+
+void Field::set_dependent_code(const Array& array) const {
+  raw_ptr()->dependent_code_ = array.raw();
+}
+
+
+void Field::RegisterDependentCode(const Code& code) const {
+  const Array& dependent = Array::Handle(dependent_code());
+
+  if (!dependent.IsNull()) {

[Ivan Posva, 2013/03/19 16:00:49]

Please add a comment what is being done here. As far as I understand you are
searching for a cleared WeakProperty. Also I am not sure it is safe and going to
stay safe to reuse a previously cleared WeakProperty.

[Vyacheslav Egorov (Google), 2013/03/19 19:57:50]

Right now it seems safe. Comment added.

+    WeakProperty& weak_property = WeakProperty::Handle();
+    for (intptr_t i = 0; i < dependent.Length(); i++) {
+      weak_property ^= dependent.At(i);
+      if (weak_property.key() == Code::null()) {
+        weak_property.set_key(code);
+        weak_property.set_value(code);
+        return;
+      }
+    }
+  }
+
+  const WeakProperty& weak_property = WeakProperty::Handle(
+      WeakProperty::New(Heap::kOld));
+  weak_property.set_key(code);
+  weak_property.set_value(code);

[Ivan Posva, 2013/03/19 16:00:49]

Please explain why both key and value are set to code. Would key be enough?

[Vyacheslav Egorov (Google), 2013/03/19 19:57:50]

Yes, key would be enough. I just wanted to fill both properties. It's like
implementing Set on top of Map as m[value] = value;

Removed.

+
+  intptr_t length = dependent.IsNull() ? 0 : dependent.Length();
+  const Array& new_dependent = Array::Handle(
+      Array::Grow(dependent, length + 1, Heap::kOld));
+  new_dependent.SetAt(length, weak_property);
+  set_dependent_code(new_dependent);
+}
+
+
+static bool ShouldDeoptimize(const Array& dependent_code, const Code& code) {

[Ivan Posva, 2013/03/19 16:00:49]

This is a bit awkwardly named. What it really does is to check whether the code
depends on this field.

[Vyacheslav Egorov (Google), 2013/03/19 19:57:50]

Done.

+  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 Field::DeoptimizeDependentCode() const {
+  const Array& code_objects = Array::Handle(dependent_code());
+
+  if (code_objects.IsNull()) {
+    return;
+  }
+  set_dependent_code(Array::Handle());
+
+  // First deoptimize all dependent methods on the stack.
+  Code& code = Code::Handle();
+  {
+    DartFrameIterator iterator;
+    StackFrame* frame = iterator.NextFrame();
+    while (frame != NULL) {
+      code = frame->LookupDartCode();
+      if (ShouldDeoptimize(code_objects, code)) {
+        DeoptimizeAt(code, frame->pc());
+      }
+      frame = iterator.NextFrame();
+    }
+  }
+
+  WeakProperty& weak_property = WeakProperty::Handle();

[Ivan Posva, 2013/03/19 16:00:49]

Please add comment what this does. As far as I understand it switches all
functions with current dependent code to unoptimized.

[Vyacheslav Egorov (Google), 2013/03/19 19:57:50]

Done.

+  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()) {
+      continue;
+    }
+
+    function ^= code.function();
+    if (function.CurrentCode() == code.raw()) {
+      ASSERT(function.HasOptimizedCode());
+      function.SwitchToUnoptimizedCode();
+    }
+  }
+}
+
+
+void Field::UpdateCid(intptr_t cid) const {

[Ivan Posva, 2013/03/19 16:00:49]

Comment about the two fields being updated separately but in sync.

[Vyacheslav Egorov (Google), 2013/03/19 19:57:50]

There is a comment in the header file. I added more comments to the body of this
function to reflect what is happening under each branch.

+  if (guarded_cid() == kIllegalCid) {
+    set_guarded_cid(cid);
+    set_is_nullable(cid == kNullCid);
+    return;
+  }
+
+  if ((cid == guarded_cid()) ||
+      ((cid == kNullCid) && is_nullable())) {
+    return;
+  }
+
+  if ((cid == kNullCid) && !is_nullable()) {
+    set_is_nullable(true);
+  } else if ((cid != kNullCid) && (guarded_cid() == kNullCid)) {
+    ASSERT(is_nullable());
+    set_guarded_cid(cid);
+  } else {
+    ASSERT(guarded_cid() != cid);
+    set_guarded_cid(kDynamicCid);
+    set_is_nullable(true);
+  }
+
+  DeoptimizeDependentCode();
+}
+
+
 void LiteralToken::set_literal(const String& literal) const {
   StorePointer(&raw_ptr()->literal_, literal.raw());
 }
 
 
 void LiteralToken::set_value(const Object& value) const {
   StorePointer(&raw_ptr()->value_, value.raw());
 }
 
 
@@ skipping 8656 matching lines @@
   }
   return result.raw();
 }
 
 
 const char* WeakProperty::ToCString() const {
   return "_WeakProperty";
 }
 
 }  // namespace dart