Refactoring of builtins and annotations in the back-end.

Before, the back-end languages had distinct instructions
- Iannot for annotations, taking structured expressions (annot_arg)
  as arguments, and producing no results'
- Ibuiltin for other builtins, using simple pseudoregs/locations/registers
  as arguments and results.

This branch enriches Ibuiltin instructions so that they take structured
expressions (builtin_arg and builtin_res) as arguments and results.
This way,
- Annotations fit the general pattern of builtin functions,
  so Iannot instructions are removed.
- EF_vload_global and EF_vstore_global become useless, as the
  same optimization can be achieved by EF_vload/vstore taking
  a structured argument of the "address of global" kind.
- Better code can be generated for builtin_memcpy between stack locations,
  or volatile accesses to stack locations.

Finally, this commit also introduces a new kind of external function,
EF_debug, which is like EF_annot but produces no observable events.
It will be used later to transport debug info through the back-end,
without preventing optimizations.

1 files changed, 3 insertions, 3 deletions

diff --git a/ia32/SelectOpproof.v b/ia32/SelectOpproof.v
index 50f0d9b6..d40ec7af 100644
--- a/ia32/SelectOpproof.v
+++ b/ia32/SelectOpproof.v
@@ -898,12 +898,12 @@ Proof.
   exists (v :: nil); split. constructor; auto. constructor. subst; simpl. rewrite Int.add_zero; auto. 
 Qed.
 
-Theorem eval_annot_arg:
+Theorem eval_builtin_arg:
   forall a v,
   eval_expr ge sp e m nil a v ->
-  CminorSel.eval_annot_arg ge sp e m (annot_arg a) v.
+  CminorSel.eval_builtin_arg ge sp e m (builtin_arg a) v.
 Proof.
-  intros until v. unfold annot_arg; case (annot_arg_match a); intros; InvEval.
+  intros until v. unfold builtin_arg; case (builtin_arg_match a); intros; InvEval.
 - constructor.
 - constructor.
 - constructor.