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, 8 insertions, 6 deletions

diff --git a/plugins/extraction/mlutil.ml b/plugins/extraction/mlutil.ml
index 3036cb134..4ab7b6f75 100644
--- a/plugins/extraction/mlutil.ml
+++ b/plugins/extraction/mlutil.ml
@@ -1205,12 +1205,14 @@ let inline_test r t =
   if not (auto_inline ()) then false
   else
     let c = match r with ConstRef c -> c | _ -> assert false in
-    let body = try (Global.lookup_constant c).const_body with _ -> None in
-    if body = None then false
-    else
-      let t1 = eta_red t in
-      let t2 = snd (collect_lams t1) in
-      not (is_fix t2) && ml_size t < 12 && is_not_strict t
+    let has_body =
+      try constant_has_body (Global.lookup_constant c)
+      with _ -> false
+    in
+    has_body &&
+      (let t1 = eta_red t in
+       let t2 = snd (collect_lams t1) in
+       not (is_fix t2) && ml_size t < 12 && is_not_strict t)
 
 let con_of_string s =
   let null = empty_dirpath in