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, 7 insertions, 12 deletions

diff --git a/checker/modops.ml b/checker/modops.ml
index b18b58a9f..4e2bbc210 100644
--- a/checker/modops.ml
+++ b/checker/modops.ml
@@ -95,19 +95,14 @@ and add_module mb env =
 
 
 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 = Const con in 
-      let const_subs = Some (Declarations.from_val const) in
-	{cb with 
-	   const_body = const_subs;
-	   const_opaque = false;
-	}
-	  
+      (* let con =  constant_of_delta resolver con in*)
+      let const = Const con in
+      let def = Def (Declarations.from_val const) in
+      { cb with const_body = def }
 
 let rec strengthen_mod env mp_from mp_to mb = 
   if Declarations.mp_in_delta mb.mod_mp mb.mod_delta then