[turbofan] Structure AccessBuilder interface a bit.

src/compiler/access-builder.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_COMPILER_ACCESS_BUILDER_H_
 #define V8_COMPILER_ACCESS_BUILDER_H_
 
 #include "src/compiler/simplified-operator.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // This access builder provides a set of static methods constructing commonly
 // used FieldAccess and ElementAccess descriptors. These descriptors serve as
 // parameters to simplified load/store operators.
 class AccessBuilder final : public AllStatic {
  public:
+  // ===========================================================================
+  // Access to heap object fields and elements (based on tagged pointer).
+
   // Provides access to HeapObject::map() field.
   static FieldAccess ForMap();
 
   // Provides access to JSObject::properties() field.
   static FieldAccess ForJSObjectProperties();
 
   // Provides access to JSObject::elements() field.
   static FieldAccess ForJSObjectElements();
 
   // Provides access to JSFunction::context() field.
   static FieldAccess ForJSFunctionContext();
 
+  // Provides access to JSFunction::shared() field.
+  static FieldAccess ForJSFunctionSharedFunctionInfo();
+
   // Provides access to JSArrayBuffer::backing_store() field.
   static FieldAccess ForJSArrayBufferBackingStore();
 
   // Provides access to JSDate fields.
   static FieldAccess ForJSDateField(JSDate::FieldIndex index);
 
   // Provides access to FixedArray::length() field.
   static FieldAccess ForFixedArrayLength();
 
   // Provides access to ExternalArray::external_pointer() field.
@@ skipping 16 matching lines @@
 
   // Provides access to String::length() field.
   static FieldAccess ForStringLength(Zone* zone);
 
   // Provides access to JSValue::value() field.
   static FieldAccess ForValue();
 
   // Provides access Context slots.
   static FieldAccess ForContextSlot(size_t index);
 
-  // Provides access to the backing store of a StatsCounter.
-  static FieldAccess ForStatsCounter();
-
   // Provides access to PropertyCell::value() field.
   static FieldAccess ForPropertyCellValue();
 
+  // Provides access to SharedFunctionInfo::feedback_vector() field.
+  static FieldAccess ForSharedFunctionInfoTypeFeedbackVector();
+
   // Provides access to FixedArray elements.
   static ElementAccess ForFixedArrayElement();
 
   // Provides access to Fixed{type}TypedArray and External{type}Array elements.
   static ElementAccess ForTypedArrayElement(ExternalArrayType type,
                                             bool is_external);
 
-  // Provides access to the charaters of sequential strings.
+  // Provides access to the characters of sequential strings.
   static ElementAccess ForSeqStringChar(String::Encoding encoding);
 
-  // Provides access to the SharedFunctionInfo in a JSFunction.
-  static FieldAccess ForJSFunctionSharedFunctionInfo();
+  // ===========================================================================
+  // Access to global per-isolate variables (based on external reference).
 
-  // Provides access to the TypeFeedbackVector in SharedFunctionInfo.
-  static FieldAccess ForSharedFunctionInfoTypeFeedbackVector();
+  // Provides access to the backing store of a StatsCounter.
+  static FieldAccess ForStatsCounter();
+
+  // ===========================================================================
+  // Access to activation records on the stack (based on frame pointer).
 
   // Provides access to the next frame pointer in a stack frame.
   static FieldAccess ForFrameCallerFramePtr();
 
   // Provides access to the marker in a stack frame.
   static FieldAccess ForFrameMarker();
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(AccessBuilder);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_ACCESS_BUILDER_H_