dart::CHA Class Reference

#include <cha.h>

Inheritance diagram for dart::CHA:

Public Member Functions
	CHA (Thread *thread)
bool	HasSubclasses (intptr_t cid) const
bool	HasOverride (const Class &cls, const String &function_name, intptr_t *subclass_count)
void	AddToGuardedClassesForSubclassCount (const Class &cls, intptr_t subclass_count)
void	AddToGuardedClassesForImplementorCid (const Class &cls, intptr_t implementor_cid)
void	AddToGuardedClassesToTrackFuture (const Class &cls)
bool	IsConsistentWithCurrentHierarchy () const
void	RegisterDependencies (const Code &code) const
bool	IsGuardedClass (intptr_t cid) const
Public Member Functions inherited from dart::ValueObject
	ValueObject ()
	~ValueObject ()

Static Public Member Functions
static bool	HasSubclasses (const Class &cls)
static bool	ConcreteSubclasses (const Class &cls, GrowableArray< intptr_t > *class_ids)
static bool	IsImplemented (const Class &cls)
static bool	HasSingleConcreteImplementation (const Class &interface, intptr_t *implementation_cid)
static bool	ClassCanBeFuture (const Class &cls)

Detailed Description

Definition at line 25 of file cha.h.

Constructor & Destructor Documentation

CHA()

dart::CHA::CHA ( Thread *  thread )

inlineexplicit

Definition at line 27 of file cha.h.

      : thread_(thread), guarded_classes_(thread->zone(), 1) {}

Member Function Documentation

AddToGuardedClassesForImplementorCid()

void dart::CHA::AddToGuardedClassesForImplementorCid	(	const Class &	cls,
		intptr_t	implementor_cid
	)

Definition at line 46 of file cha.cc.

                                                                         {
  ASSERT(implementor_cid != kIllegalCid);
  ASSERT(implementor_cid != kDynamicCid);
  AddToGuardedClasses(cls, -1, implementor_cid, false);
}

AddToGuardedClassesForSubclassCount()

void dart::CHA::AddToGuardedClassesForSubclassCount	(	const Class &	cls,
		intptr_t	subclass_count
	)

Definition at line 40 of file cha.cc.

                                                                       {
  ASSERT(subclass_count >= 0);
  AddToGuardedClasses(cls, subclass_count, kIllegalCid, false);
}

AddToGuardedClassesToTrackFuture()

void dart::CHA::AddToGuardedClassesToTrackFuture

(

const Class &

cls

)

Definition at line 53 of file cha.cc.

                                                           {
  AddToGuardedClasses(cls, -1, kIllegalCid, true);
}

ClassCanBeFuture()

bool dart::CHA::ClassCanBeFuture ( const Class &  cls )

static

Definition at line 160 of file cha.cc.

                                           {
  if (cls.can_be_future()) {
    return true;
  }
 
  // Class cannot be Future with the current set of
  // finalized classes. However, as new classes are loaded
  // and finalized, there could be a new subtype of [cls]
  // which is also a subtype of Future.
  // We should deoptimize in such cases.
  Thread* thread = Thread::Current();
  if (FLAG_use_cha_deopt || thread->isolate_group()->all_classes_finalized()) {
    if (FLAG_use_cha_deopt) {
      CHA& cha = thread->compiler_state().cha();
      cha.AddToGuardedClassesToTrackFuture(cls);
    }
    return false;
  }
 
  // Conservatively assume that class can be Future.
  return true;
}

ConcreteSubclasses()

bool dart::CHA::ConcreteSubclasses ( const Class &  cls, GrowableArray< intptr_t > *  class_ids  )

static

Definition at line 93 of file cha.cc.

                                                                 {
  if (cls.InVMIsolateHeap()) return false;
  if (cls.IsObjectClass()) return false;
  if (cls.has_dynamically_extendable_subtypes()) return false;
 
  if (!cls.is_abstract()) {
    class_ids->Add(cls.id());
  }
 
  // This is invoked from precompiler only, we can use unsafe version of
  // Class::direct_subclasses getter.
  ASSERT(FLAG_precompiled_mode);
  const GrowableObjectArray& direct_subclasses =
      GrowableObjectArray::Handle(cls.direct_subclasses_unsafe());
  if (direct_subclasses.IsNull()) {
    return true;
  }
  Class& subclass = Class::Handle();
  for (intptr_t i = 0; i < direct_subclasses.Length(); i++) {
    subclass ^= direct_subclasses.At(i);
    if (!ConcreteSubclasses(subclass, class_ids)) {
      return false;
    }
  }
  return true;
}

HasOverride()

bool dart::CHA::HasOverride	(	const Class &	cls,
		const String &	function_name,
		intptr_t *	subclass_count
	)

Definition at line 227 of file cha.cc.

                                                  {
  // Can't track dependencies for classes on the VM heap since those are
  // read-only.
  // TODO(fschneider): Enable tracking of CHA dependent code for VM heap
  // classes.
  if (cls.InVMIsolateHeap()) return true;
 
  // Subclasses of Object are not tracked by CHA. Safely assume that overrides
  // exist.
  if (cls.IsObjectClass()) {
    return true;
  }
 
  SafepointReadRwLocker ml(thread_, thread_->isolate_group()->program_lock());
  const GrowableObjectArray& cls_direct_subclasses =
      GrowableObjectArray::Handle(thread_->zone(), cls.direct_subclasses());
  if (cls_direct_subclasses.IsNull()) {
    return false;
  }
  Class& direct_subclass = Class::Handle(thread_->zone());
  for (intptr_t i = 0; i < cls_direct_subclasses.Length(); i++) {
    direct_subclass ^= cls_direct_subclasses.At(i);
    // Unfinalized classes are treated as nonexistent for CHA purposes,
    // as that means that no instance of that class exists at runtime.
    if (!direct_subclass.is_finalized()) {
      continue;
    }
 
    if (direct_subclass.LookupDynamicFunctionUnsafe(function_name) !=
        Function::null()) {
      return true;
    }
 
    if (HasOverride(direct_subclass, function_name, subclasses_count)) {
      return true;
    }
 
    (*subclasses_count)++;
  }
 
  return false;
}

HasSingleConcreteImplementation()

bool dart::CHA::HasSingleConcreteImplementation ( const Class &  interface, intptr_t *  implementation_cid  )

static

Definition at line 132 of file cha.cc.

                                                                        {
  intptr_t cid = interface.implementor_cid();
  if ((cid == kIllegalCid) || (cid == kDynamicCid) ||
      interface.has_dynamically_extendable_subtypes()) {
    // No implementations / multiple implementations.
    *implementation_cid = kDynamicCid;
    return false;
  }
 
  Thread* thread = Thread::Current();
  if (FLAG_use_cha_deopt || thread->isolate_group()->all_classes_finalized()) {
    if (FLAG_trace_cha) {
      THR_Print("  **(CHA) Type has one implementation: %s\n",
                interface.ToCString());
    }
    if (FLAG_use_cha_deopt) {
      CHA& cha = thread->compiler_state().cha();
      cha.AddToGuardedClassesForImplementorCid(interface, cid);
    }
    *implementation_cid = cid;
    return true;
  } else {
    *implementation_cid = kDynamicCid;
    return false;
  }
}

HasSubclasses() [1/2]

bool dart::CHA::HasSubclasses ( const Class &  cls )

static

Definition at line 64 of file cha.cc.

                                        {
  ASSERT(!cls.IsNull());
  ASSERT(!IsInternalOnlyClassId(cls.id()));
  // Can't track dependencies for classes on the VM heap since those are
  // read-only.
  // TODO(fschneider): Enable tracking of CHA dependent code for VM heap
  // classes.
  if (cls.InVMIsolateHeap()) return true;
 
  if (cls.IsObjectClass()) {
    // Class Object has subclasses, although we do not keep track of them.
    return true;
  }
 
  if (cls.has_dynamically_extendable_subtypes()) return true;
 
  Thread* thread = Thread::Current();
  SafepointReadRwLocker ml(thread, thread->isolate_group()->program_lock());
  const GrowableObjectArray& direct_subclasses =
      GrowableObjectArray::Handle(cls.direct_subclasses());
  return !direct_subclasses.IsNull() && (direct_subclasses.Length() > 0);
}

HasSubclasses() [2/2]

bool dart::CHA::HasSubclasses

(

intptr_t

cid

)

const

Definition at line 87 of file cha.cc.

                                          {
  const ClassTable& class_table = *thread_->isolate_group()->class_table();
  Class& cls = Class::Handle(thread_->zone(), class_table.At(cid));
  return HasSubclasses(cls);
}

IsConsistentWithCurrentHierarchy()

bool dart::CHA::IsConsistentWithCurrentHierarchy

(

)

const

Definition at line 202 of file cha.cc.

                                                 {
  for (intptr_t i = 0; i < guarded_classes_.length(); i++) {
    if (guarded_classes_[i].subclass_count != -1) {
      intptr_t current_subclass_count =
          CountFinalizedSubclasses(thread_, *guarded_classes_[i].cls);
      if (guarded_classes_[i].subclass_count != current_subclass_count) {
        return false;  // New subclass appeared during compilation.
      }
    }
    if (guarded_classes_[i].implementor_cid != kIllegalCid) {
      intptr_t current_implementor_cid =
          guarded_classes_[i].cls->implementor_cid();
      if (guarded_classes_[i].implementor_cid != current_implementor_cid) {
        return false;  // New implementor appeared during compilation.
      }
    }
    if (guarded_classes_[i].track_future) {
      if (guarded_classes_[i].cls->can_be_future()) {
        return false;
      }
    }
  }
  return true;
}

IsGuardedClass()

bool dart::CHA::IsGuardedClass

(

intptr_t

cid

)

const

Definition at line 57 of file cha.cc.

                                           {
  for (intptr_t i = 0; i < guarded_classes_.length(); ++i) {
    if (guarded_classes_[i].cls->id() == cid) return true;
  }
  return false;
}

IsImplemented()

bool dart::CHA::IsImplemented ( const Class &  cls )

static

Definition at line 121 of file cha.cc.

                                        {
  // Can't track dependencies for classes on the VM heap since those are
  // read-only.
  // TODO(fschneider): Enable tracking of CHA dependent code for VM heap
  // classes.
  if (cls.InVMIsolateHeap()) return true;
  if (cls.has_dynamically_extendable_subtypes()) return true;
 
  return cls.is_implemented();
}

RegisterDependencies()

void dart::CHA::RegisterDependencies

(

const Code &

code

)

const

Definition at line 272 of file cha.cc.

                                                     {
  for (intptr_t i = 0; i < guarded_classes_.length(); ++i) {
    guarded_classes_[i].cls->RegisterCHACode(code);
  }
}

---

The documentation for this class was generated from the following files:

• third_party/dart-lang/sdk/runtime/vm/compiler/cha.h
• third_party/dart-lang/sdk/runtime/vm/compiler/cha.cc