Lazy loading of opaque proofs: fast as -dont-load-proofs without its drawbacks

 The recent experiment with -dont-load-proofs in the stdlib showed that
 this options isn't fully safe: some axioms were generated (Include ?
 functor application ? This is still to be fully understood).

 Instead, I've implemented an idea of Yann: only load opaque proofs when
 we need them. This is almost as fast as -dont-load-proofs (on the stdlib,
 we're now 15% faster than before instead of 20% faster with -dont-load-proofs),
 but fully compatible with Coq standard behavior.

 Technically, the const_body field of Declarations.constant_body now regroup
 const_body + const_opaque + const_inline in a ternary type. It is now either:
  - Undef : an axiom or parameter, with an inline info
  - Def : a transparent definition, with a constr_substituted
  - OpaqueDef : an opaque definition, with a lazy constr_substitued
 Accessing the lazy constr of an OpaqueDef might trigger the read on disk of
 the final section of a .vo, where opaque proofs are located.

 Some functions (body_of_constant, is_opaque, constant_has_body) emulate
 the behavior of the old fields. The rest of Coq (including the checker)
 has been adapted accordingly, either via direct access to the new const_body
 or via these new functions. Many places look nicer now (ok, subjective notion).

 There are now three options: -lazy-load-proofs (default), -force-load-proofs
 (earlier semantics), -dont-load-proofs. Note that -outputstate now implies
 -force-load-proofs (otherwise the marshaling fails on some delayed lazy).

 On the way, I fixed what looked like a bug : a module type
 (T with Definition x := c) was accepted even when x in T was opaque.
 I also tried to clarify Subtyping.check_constant.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@13952 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 11 insertions, 16 deletions

diff --git a/kernel/modops.ml b/kernel/modops.ml
index 6d4ebb989b..df9b7e81f6 100644
--- a/kernel/modops.ml
+++ b/kernel/modops.ml
@@ -290,21 +290,17 @@ and add_module mb env =
       | _ -> anomaly "Modops:the evaluation of the structure failed "
 
 let strengthen_const env mp_from l cb resolver = 
-  match cb.const_opaque, cb.const_body with
-  | false, Some _ -> cb
-  | true, Some _ 
-  | _, None ->
+  match cb.const_body with
+    | Def _ -> cb
+    | _ ->
       let con = make_con mp_from empty_dirpath l in
       let con =  constant_of_delta resolver con in
       let const = mkConst con in 
-      let const_subs = Some (Declarations.from_val const) in
-	{cb with 
-	   const_body = const_subs;
-	   const_opaque = false;
-	   const_body_code = Cemitcodes.from_val
-            (compile_constant_body env const_subs false)
-	}
-	  
+      let def = Def (Declarations.from_val const) in
+      { cb with
+	const_body = def;
+	const_body_code = Cemitcodes.from_val (compile_constant_body env def)
+      }
 
 let rec strengthen_mod env mp_from mp_to mb = 
   if mp_in_delta mb.mod_mp mb.mod_delta then
@@ -401,10 +397,9 @@ let inline_delta_resolver env inl mp mbid mtb delta =
 	try
 	  let constant = lookup_constant con' env in
 	  let l = make_inline delta r in
-	  if constant.Declarations.const_opaque then l
-	  else match constant.Declarations.const_body with
-	    | None -> l
-	    | Some body ->
+	  match constant.const_body with
+	    | Undef _ | OpaqueDef _ -> l
+	    | Def body ->
 	      let constr = Declarations.force body in
 	      add_inline_constr_delta_resolver con lev constr l
 	with Not_found ->