Propagated information from the reduction tactics to the kernel so

that the kernel conversion solves the delta/delta critical pair the
same way the tactics did. This allows to improve Qed time when slow
down is due to conversion having (arbitrarily) made the wrong choice.
Propagation is done thanks to a new kind of cast called REVERTcast.

Notes:
- Vm conversion not modified
- size of vo generally grows because of additional casts
- this remains a heuristic... for the record, when a reduction tactic
  is applied on the goal t leading to new goal t', this is translated
  in the kernel in a conversion t' <= t where, hence, reducing in t'
  must be preferred; what the propagation of reduction cast to the
  kernel does not do is whether it is preferable to first unfold c or
  to first compare u' and u in "c u' = c u"; in particular,
  intermediate casts are sometimes useful to solve this kind of issues
  (this is the case e.g. in Nijmegen/LinAlg/subspace_dim.v where the
  combination "simpl;red" needs the intermediate cast to ensure Qed
  answers quickly); henceforth the merge of nested casts in mkCast is
  deactivated
- for tactic "change", REVERTcast should be used when conversion is in
  the hypotheses, but convert_hyp does not (yet) support this (would
  require e.g. that convert_hyp overwrite some given hyp id with a
  body-cleared let-binding new_id := Cast(old_id,REVERTCast,t))

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@14407 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/conv_oracle.ml b/kernel/conv_oracle.ml
index 6ad4c38fc6..92109258d7 100644
--- a/kernel/conv_oracle.ml
+++ b/kernel/conv_oracle.ml
@@ -56,12 +56,12 @@ let get_transp_state () =
 
 (* Unfold the first constant only if it is "more transparent" than the
    second one. In case of tie, expand the second one. *)
-let oracle_order k1 k2 =
+let oracle_order l2r k1 k2 =
   match get_strategy k1, get_strategy k2 with
     | Expand, _ -> true
     | Level n1, Opaque -> true
     | Level n1, Level n2 -> n1 < n2
-    | _ -> false (* expand k2 *)
+    | _ -> l2r (* use recommended default *)
 
 (* summary operations *)
 let init() = (cst_opacity := Cmap.empty; var_opacity := Idmap.empty)