A step towards RTTI in Mercury.

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A step towards RTTI in Mercury.

This step redefines the representation of pseudo-typeinfos inside the compiler
to be identical to the representation we will need for efficient interpretation
of RTTI data structures in Mercury. Later steps will do likewise for
typectorinfos. In the end, we will have two implementations of RTTI:
the current low-level, very efficient one written in C, which will be used
by the C backends (both LLDS and MLDS), and a new, higher-level one
which will use Mercury data structures and Mercury predicates for
interpretation (along the lines of library/rtti_implementation.m)
for the Java and IL backends.

A large part of this change concerns the fact that pseudo-typeinfos can now
contain typeinfos as well as other pseudo-typeinfos, and they do in the
frequent case that the type of an argument is ground. Given that typeinfos
are just special cases of pseudo-typeinfos, the code for handling the two
types is usually similar, with common code factored out when relevant.

In the process of redesigning the data structures concerning (pseudo-)
typeinfos, I also fixed an old naming scheme that has become misleading.
The representation of a (pseudo-) typeinfo depends on whether the principal
type constructor is fixed arity or not. We used to denote this distinction
with the phrases first-order vs higher-order, since at first the only variable
arity type constructors were pred and func. However, this hasn't been true
since we added tuples. I have changed the naming scheme to be fixed-arity vs
variable-arity.

compiler/rtti.m:
	Add new, purely Mercury data structures for representing typeinfos
	and pseudo-typeinfos, designed both for efficient interpretation
	and as a source for the generation of static data structures in C.

compiler/pseudo_type_info.m:
	Delete the type definitions here, since they are superseded by the new
	definitions in rtti.m.

	Add predicates for constructing typeinfos as well as pseudo-typeinfos,
	since now we need those too.

	Conform to the changed data structures for (pseudo-) typeinfos.

compiler/ll_pseudo_type_info.m:
compiler/ml_closure_gen.m:
compiler/rtti_out.m:
compiler/rtti_to_mlds.m:
compiler/opt_debug.m:
compiler/type_ctor_info.m:
	Conform to the changed data structures for (pseudo-) typeinfos.

compiler/mlds.m:
	Since the MLDS now refers to type_infos, add their type
	(mlds__type_info_type) to the list of types the MLDS knows about.

compiler/ml_code_util.m:
compiler/mlds_to_c.m:
compiler/mlds_to_il.m:
compiler/mlds_to_java.m:
	Handle mlds__type_info_type.

compiler/mlds_to_gcc.m:
	Conform to the changed data structures for (pseudo-) typeinfos,
	and handle mlds__type_info_type.

runtime/mercury_bootstrap.h:
	Override the compiler-generated names of the type_ctor_infos of the
	variable arity type constructors. The MLDS backend requires these
	to be module qualified; the LLDS backend requires them to be
	unqualified. This is a problem because the same code now generates
	the compiler's internal representation of pseudo-typeinfos for both
	backends.

	The temporary solution is to have the compiler generate these names
	module qualified, and have these macros convert them to the unqualified
	form. (The long term solution should be to always module qualify
	everything, but doing that is for another change.)

runtime/mercury_type_info.h:
	Change the naming scheme from first order vs higher order to fixed
	arity vs variable arity.

library/construct.m:
library/deconstruct.m:
runtime/mercury.c:
runtime/mercury_construct.c:
runtime/mercury_deconstruct.c:
runtime/mercury_deep_copy_body.h:
runtime/mercury_make_type_info_body.h:
runtime/mercury_ml_expand_body.h:
runtime/mercury_tabling.c:
runtime/mercury_type_desc.c:
runtime/mercury_type_info.c:
runtime/mercury_unify_compare_body.h:
	Conform to the new naming scheme.

runtime/mercury.h:
	Conform to the new naming scheme.

	Declare fixed and variable arity types for typeinfos as well as
	pseudo-typeinfos, since pseudo-typeinfos can now refer to typeinfos.

runtime/mercury_deconstruct.c

@@ -232,7 +232,7 @@ MR_named_arg_num(MR_TypeInfo type_info, MR_Word *term_ptr,
 
         case MR_TYPECTOR_REP_EQUIV:
             eqv_type_info = MR_create_type_info(
-                MR_TYPEINFO_GET_FIRST_ORDER_ARG_VECTOR(type_info),
+                MR_TYPEINFO_GET_FIXED_ARITY_ARG_VECTOR(type_info),
                 MR_type_ctor_layout(type_ctor_info).layout_equiv);
             return MR_named_arg_num(eqv_type_info, term_ptr, arg_name,
                 arg_num_ptr);