Yet more type system tests

src/types.h

Index: src/types.h
diff --git a/src/types.h b/src/types.h
index 16d80b8f8d44a314da3cae77d276b3f6545b38dc..6824575ebc37b1cd3c452faa43c185e9c6c2fbe2 100644
--- a/src/types.h
+++ b/src/types.h
@@ -10,6 +10,8 @@
 namespace v8 {
 namespace internal {
 
+// SUMMARY
+//
 // A simple type system for compiler-internal use. It is based entirely on
 // union types, and all subtyping hence amounts to set inclusion. Besides the
 // obvious primitive types and some predefined unions, the type language also
@@ -19,6 +21,8 @@ namespace internal {
 // Types consist of two dimensions: semantic (value range) and representation.
 // Both are related through subtyping.
 //
+// SEMANTIC DIMENSION
+//
 // The following equations and inequations hold for the semantic axis:
 //
 //   None <= T
@@ -45,6 +49,8 @@ namespace internal {
 // TODO(rossberg): the latter is not currently true for proxies, because of fix,
 // but will hold once we implement direct proxies.
 //
+// REPRESENTATIONAL DIMENSION
+//
 // For the representation axis, the following holds:
 //
 //   None <= R
@@ -69,6 +75,8 @@ namespace internal {
 //   SignedSmall /\ TaggedInt       (a 'smi')
 //   Number /\ TaggedPtr            (a heap number)
 //
+// PREDICATES
+//
 // There are two main functions for testing types:
 //
 //   T1->Is(T2)     -- tests whether T1 is included in T2 (i.e., T1 <= T2)
@@ -84,6 +92,18 @@ namespace internal {
 // existing assumptions or tests.
 // Consequently, do not use pointer equality for type tests, always use Is!
 //
+// PROPERTIES
+//
+// Various formal properties hold for constructors, operators, and predicates
+// over types. For example, constructors are injective, subtyping is a partial
+// order, and union and intersection satisfy the usual algebraic properties.
+//
+// See test/cctest/test-typing.cc for a comprehensive executable specification,

[Benedikt Meurer, 2014/04/10 10:54:50]

Nit: test-types.cc

+// especially with respect to the more exotic temporal constructors and
+// predicates (prefixed 'Now').
+//
+// IMPLEMENTATION
+//
 // Internally, all 'primitive' types, and their unions, are represented as
 // bitsets. Class is a heap pointer to the respective map. Only Constant's, or
 // unions containing Class'es or Constant's, currently require allocation.