Minor clarifications and simplifications.

src/types.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_TYPES_H_
 #define V8_TYPES_H_
 
 #include "src/factory.h"
 #include "src/handles.h"
 #include "src/ostreams.h"
@@ skipping 50 matching lines @@
 // However, we also define a 'temporal' variant of the subtyping relation that
 // considers the _current_ state only, i.e., Constant(x) <_now Class(map(x)).
 //
 // REPRESENTATIONAL DIMENSION
 //
 // For the representation axis, the following holds:
 //
 //   None <= R
 //   R <= Any
 //
-//   UntaggedInt <= UntaggedInt8 \/ UntaggedInt16 \/ UntaggedInt32)
-//   UntaggedFloat <= UntaggedFloat32 \/ UntaggedFloat64
-//   UntaggedNumber <= UntaggedInt \/ UntaggedFloat
-//   Untagged <= UntaggedNumber \/ UntaggedPtr
-//   Tagged <= TaggedInt \/ TaggedPtr
+//   UntaggedInt = UntaggedInt8 \/ UntaggedInt16 \/ UntaggedInt32)

[rossberg, 2014/07/23 14:53:03]

Should include Int1 now. Also, spurious paren.

[neis, 2014/07/23 15:17:19]

Done.

+//   UntaggedFloat = UntaggedFloat32 \/ UntaggedFloat64
+//   UntaggedNumber = UntaggedInt \/ UntaggedFloat
+//   Untagged = UntaggedNumber \/ UntaggedPtr
+//   Tagged = TaggedInt \/ TaggedPtr
 //
 // Subtyping relates the two dimensions, for example:
 //
 //   Number <= Tagged \/ UntaggedNumber
 //   Object <= TaggedPtr \/ UntaggedPtr
 //
 // That holds because the semantic type constructors defined by the API create
 // types that allow for all possible representations, and dually, the ones for
 // representation types initially include all semantic ranges. Representations
 // can then e.g. be narrowed for a given semantic type using intersection:
@@ skipping 518 matching lines @@
         ? BitsetType::New(BitsetType::Lub(*Config::as_class(this)), region)
         : this->Get(0);
   }
   i::Handle<i::Map> Map() {
     return Config::is_class(this)
         ? Config::as_class(this)
         : this->template GetValue<i::Map>(1);
   }
 
   static ClassHandle New(
       i::Handle<i::Map> map, TypeHandle bound, Region* region) {

[rossberg, 2014/07/23 14:53:03]

While you're at it, can you also add assertions for bound? Here, for Constant,
and for Context? (using InherentLub)

[neis, 2014/07/23 15:17:19]

Done.

     ClassHandle type = Config::template cast<ClassType>(
         StructuralType::New(StructuralType::kClassTag, 2, region));
     type->Set(0, bound);
     type->SetValue(1, map);
     return type;
   }
 
   static ClassHandle New(i::Handle<i::Map> map, Region* region) {
     ClassHandle type =
         Config::template cast<ClassType>(Config::from_class(map, region));
@@ skipping 47 matching lines @@
 
 template<class Config>
 class TypeImpl<Config>::RangeType : public StructuralType {
  public:
   TypeHandle Bound() { return this->Get(0); }
   double Min() { return this->template GetValue<i::HeapNumber>(1)->value(); }
   double Max() { return this->template GetValue<i::HeapNumber>(2)->value(); }
 
   static RangeHandle New(
       double min, double max, TypeHandle bound, Region* region) {
     ASSERT(SEMANTIC(bound->AsBitset() | BitsetType::kNumber)

[rossberg, 2014/07/23 14:53:03]

Make this a proper subtype check for both axes, and use InherentLub.

[neis, 2014/07/23 15:17:18]

Done.

            == SEMANTIC(BitsetType::kNumber));
     ASSERT(!std::isnan(min) && !std::isnan(max) && min <= max);
     RangeHandle type = Config::template cast<RangeType>(
         StructuralType::New(StructuralType::kRangeTag, 3, region));
     type->Set(0, bound);
     Factory* factory = Config::isolate(region)->factory();
     type->SetValue(1, factory->NewHeapNumber(min));
     type->SetValue(2, factory->NewHeapNumber(max));
     return type;
   }
@@ skipping 43 matching lines @@
 // -----------------------------------------------------------------------------
 // Array types.
 
 template<class Config>
 class TypeImpl<Config>::ArrayType : public StructuralType {
  public:
   TypeHandle Bound() { return this->Get(0); }
   TypeHandle Element() { return this->Get(1); }
 
   static ArrayHandle New(TypeHandle element, TypeHandle bound, Region* region) {
     ASSERT(SEMANTIC(bound->AsBitset()) == SEMANTIC(BitsetType::kArray));

[rossberg, 2014/07/23 14:53:03]

Same here.

[neis, 2014/07/23 15:17:18]

Done.

     ArrayHandle type = Config::template cast<ArrayType>(
         StructuralType::New(StructuralType::kArrayTag, 2, region));
     type->Set(0, bound);
     type->Set(1, element);
     return type;
   }
 
   static ArrayHandle New(TypeHandle element, Region* region) {
     TypeHandle bound = BitsetType::New(BitsetType::kArray, region);
     return New(element, bound, region);
@@ skipping 16 matching lines @@
   TypeHandle Bound() { return this->Get(0); }
   TypeHandle Result() { return this->Get(1); }
   TypeHandle Receiver() { return this->Get(2); }
   TypeHandle Parameter(int i) { return this->Get(3 + i); }
 
   void InitParameter(int i, TypeHandle type) { this->Set(3 + i, type); }
 
   static FunctionHandle New(
       TypeHandle result, TypeHandle receiver, TypeHandle bound,
       int arity, Region* region) {
     ASSERT(SEMANTIC(bound->AsBitset()) == SEMANTIC(BitsetType::kFunction));

[rossberg, 2014/07/23 14:53:03]

And here.

[neis, 2014/07/23 15:17:19]

Done.

     FunctionHandle type = Config::template cast<FunctionType>(
         StructuralType::New(StructuralType::kFunctionTag, 3 + arity, region));
     type->Set(0, bound);
     type->Set(1, result);
     type->Set(2, receiver);
     return type;
   }
 
   static FunctionHandle New(
       TypeHandle result, TypeHandle receiver, int arity, Region* region) {
@@ skipping 187 matching lines @@
   bool Narrows(BoundsImpl that) {
     return that.lower->Is(this->lower) && this->upper->Is(that.upper);
   }
 };
 
 typedef BoundsImpl<ZoneTypeConfig> Bounds;
 
 } }  // namespace v8::internal
 
 #endif  // V8_TYPES_H_