[turbofan] Structure AccessBuilder interface a bit.

src/compiler/access-builder.h

Index: src/compiler/access-builder.h
diff --git a/src/compiler/access-builder.h b/src/compiler/access-builder.h
index e4d1332771d8fa4306afb3f5599be74864a794ff..240ffdcb5dac59d11998b0bf7cf0c0b386f61197 100644
--- a/src/compiler/access-builder.h
+++ b/src/compiler/access-builder.h
@@ -16,6 +16,9 @@ namespace compiler {
 // 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();
 
@@ -28,6 +31,9 @@ class AccessBuilder final : public AllStatic {
   // 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();
 
@@ -64,12 +70,12 @@ class AccessBuilder final : public AllStatic {
   // 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();
 
@@ -77,14 +83,17 @@ class AccessBuilder final : public AllStatic {
   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();