1 files changed, 75 insertions, 13 deletions

diff --git a/arm/linux/Stacklayout.v b/arm/linux/Stacklayout.v
index b374bfd..4521114 100644
--- a/arm/linux/Stacklayout.v
+++ b/arm/linux/Stacklayout.v
@@ -28,12 +28,6 @@ Require Import Bounds.
 - Pointer to activation record of the caller.
 - Space for the stack-allocated data declared in Cminor.
 
-To facilitate some of the proofs, the Cminor stack-allocated data
-starts at offset 0; the preceding areas in the activation record
-therefore have negative offsets.  This part (with negative offsets)
-is called the ``frame'', by opposition with the ``Cminor stack data''
-which is the part with positive offsets.
-
 The [frame_env] compilation environment records the positions of
 the boundaries between areas in the frame part.
 *)
@@ -49,7 +43,8 @@ Record frame_env : Type := mk_frame_env {
   fe_num_int_callee_save: Z;
   fe_ofs_float_local: Z;
   fe_ofs_float_callee_save: Z;
-  fe_num_float_callee_save: Z
+  fe_num_float_callee_save: Z;
+  fe_stack_data: Z
 }.
 
 (** Computation of the frame environment from the bounds of the current
@@ -63,17 +58,84 @@ Definition make_env (b: bounds) :=
   let ofcs := ofl + 8 * b.(bound_float_local) in (* float callee-saves *)
   let ora := ofcs + 8 * b.(bound_float_callee_save) in (* retaddr *)
   let olink := ora + 4 in (* back link *)
-  let sz := olink + 4 in (* total frame size *)
+  let ostkdata := olink + 4 in (* stack data *)
+  let sz := align (ostkdata + b.(bound_stack_data)) 8 in
   mk_frame_env sz olink ora
                   oil oics b.(bound_int_callee_save)
-                  ofl ofcs b.(bound_float_callee_save).
+                  ofl ofcs b.(bound_float_callee_save)
+                  ostkdata.
 
+(** Separation property *)
 
-Remark align_float_part:
+Remark frame_env_separated:
   forall b,
-  4 * bound_outgoing b + 4 * bound_int_local b + 4 * bound_int_callee_save b <=
-  align (4 * bound_outgoing b + 4 * bound_int_local b + 4 * bound_int_callee_save b) 8.
+  let fe := make_env b in
+  0 <= fe_ofs_arg
+  /\ fe_ofs_arg + 4 * b.(bound_outgoing) <= fe.(fe_ofs_int_local)
+  /\ fe.(fe_ofs_int_local) + 4 * b.(bound_int_local) <= fe.(fe_ofs_int_callee_save)
+  /\ fe.(fe_ofs_int_callee_save) + 4 * b.(bound_int_callee_save) <= fe.(fe_ofs_float_local)
+  /\ fe.(fe_ofs_float_local) + 8 * b.(bound_float_local) <= fe.(fe_ofs_float_callee_save)
+  /\ fe.(fe_ofs_float_callee_save) + 8 * b.(bound_float_callee_save) <= fe.(fe_ofs_retaddr)
+  /\ fe.(fe_ofs_retaddr) + 4 <= fe.(fe_ofs_link)
+  /\ fe.(fe_ofs_link) + 4 <= fe.(fe_stack_data)
+  /\ fe.(fe_stack_data) + b.(bound_stack_data) <= fe.(fe_size).
 Proof.
-  intros. apply align_le. omega.
+  intros.
+  generalize (align_le (fe.(fe_ofs_int_callee_save) + 4 * b.(bound_int_callee_save)) 8 (refl_equal _)).
+  generalize (align_le (fe.(fe_stack_data) + b.(bound_stack_data)) 8 (refl_equal _)).
+  unfold fe, make_env, fe_size, fe_ofs_link, fe_ofs_retaddr,
+    fe_ofs_int_local, fe_ofs_int_callee_save,
+    fe_num_int_callee_save,
+    fe_ofs_float_local, fe_ofs_float_callee_save, fe_num_float_callee_save,
+    fe_stack_data, fe_ofs_arg.
+  intros.
+  generalize (bound_int_local_pos b); intro;
+  generalize (bound_float_local_pos b); intro;
+  generalize (bound_int_callee_save_pos b); intro;
+  generalize (bound_float_callee_save_pos b); intro;
+  generalize (bound_outgoing_pos b); intro;
+  generalize (bound_stack_data_pos b); intro.
+  omega.
 Qed.
 
+(** Alignment property *)
+
+Remark frame_env_aligned:
+  forall b,
+  let fe := make_env b in
+  (4 | fe.(fe_ofs_link))
+  /\ (4 | fe.(fe_ofs_int_local))
+  /\ (4 | fe.(fe_ofs_int_callee_save))
+  /\ (8 | fe.(fe_ofs_float_local))
+  /\ (8 | fe.(fe_ofs_float_callee_save))
+  /\ (4 | fe.(fe_ofs_retaddr))
+  /\ (4 | fe.(fe_stack_data))
+  /\ (8 | fe.(fe_size)).
+Proof.
+  intros.
+  unfold fe, make_env, fe_size, fe_ofs_link, fe_ofs_retaddr,
+    fe_ofs_int_local, fe_ofs_int_callee_save,
+    fe_num_int_callee_save,
+    fe_ofs_float_local, fe_ofs_float_callee_save, fe_num_float_callee_save,
+    fe_stack_data.
+  set (x1 := 4 * bound_outgoing b).
+  assert (4 | x1). unfold x1; exists (bound_outgoing b); ring.
+  set (x2 := x1 + 4 * bound_int_local b).
+  assert (4 | x2). unfold x2; apply Zdivide_plus_r; auto. exists (bound_int_local b); ring.
+  set (x3 := x2 + 4 * bound_int_callee_save b).
+  set (x4 := align x3 8).
+  assert (8 | x4). unfold x4. apply align_divides. omega.
+  set (x5 := x4 + 8 * bound_float_local b).
+  assert (8 | x5). unfold x5. apply Zdivide_plus_r; auto. exists (bound_float_local b); ring.
+  set (x6 := x5 + 8 * bound_float_callee_save b).
+  assert (4 | x6).
+    apply Zdivides_trans with 8. exists 2; auto.
+    unfold x6. apply Zdivide_plus_r; auto. exists (bound_float_callee_save b); ring.
+  set (x7 := x6 + 4).
+  assert (4 | x7). unfold x7; apply Zdivide_plus_r; auto. exists 1; auto.
+  set (x8 := x7 + 4).
+  assert (4 | x8). unfold x8; apply Zdivide_plus_r; auto. exists 1; auto.
+  set (x9 := align (x8 + bound_stack_data b) 8).
+  assert (8 | x9). unfold x9; apply align_divides. omega.
+  tauto.
+Qed.