Merge the various $(ARCH)/$(VARIANT)/xxx.v files into $(ARCH)/xxx.v.

The only platform where we have two variants is ARM, and it's easier
to share the callling convention code between the two than to maintain 
both variants separately.


git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2540 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e

6 files changed, 125 insertions, 718 deletions

diff --git a/arm/Archi.v b/arm/Archi.v
index 5657f31..1306459 100644
--- a/arm/Archi.v
+++ b/arm/Archi.v
@@ -46,3 +46,6 @@ Definition choose_binop_pl_32 (s1: bool) (pl1: nan_pl 24) (s2: bool) (pl2: nan_p
 Global Opaque big_endian
               default_pl_64 choose_binop_pl_64
               default_pl_32 choose_binop_pl_32.
+
+Inductive abi_kind := Softfloat | Hardfloat.
+Parameter abi: abi_kind.
diff --git a/arm/hardfloat/Conventions1.v b/arm/Conventions1.v
index 40a761c..1689c77 100644
--- a/arm/hardfloat/Conventions1.v
+++ b/arm/Conventions1.v
@@ -17,6 +17,7 @@ Require Import Coqlib.
 Require Import AST.
 Require Import Events.
 Require Import Locations.
+Require Archi.
 
 (** * Classification of machine registers *)
 
@@ -231,7 +232,12 @@ Qed.
 (** The result value of a function is passed back to the caller in
   registers [R0] or [F0] or [R0,R1], depending on the type of the
   returned value.  We treat a function without result as a function
-  with one integer result. *)
+  with one integer result.
+
+  For the "softfloat" convention, results of FP types should be passed
+  in [R0] or [R0,R1].  This doesn't fit the CompCert register model,
+  so we have code in [arm/PrintAsm.ml] that inserts additional moves
+  to/from [F0]. *)
 
 Definition loc_result (s: signature) : list mreg :=
   match s.(sig_res) with
@@ -264,7 +270,8 @@ Qed.
 
 (** ** Location of function arguments *)
 
-(** We use the following calling conventions, adapted from the ARM EABI-HF:
+(** For the "hardfloat" configuration, we use the following calling conventions,
+    adapted from the ARM EABI-HF:
 - The first 4 integer arguments are passed in registers [R0] to [R3].
 - The first 2 long integer arguments are passed in an aligned pair of
   two integer registers.
@@ -292,32 +299,33 @@ Definition ireg_param (n: Z) : mreg :=
 Definition freg_param (n: Z) : mreg :=
   match list_nth_z float_param_regs n with Some r => r | None => F0 end.
 
-Fixpoint loc_arguments_rec
+Fixpoint loc_arguments_hf
      (tyl: list typ) (ir fr ofs: Z) {struct tyl} : list loc :=
   match tyl with
   | nil => nil
   | (Tint | Tany32) as ty :: tys =>
       if zlt ir 4
-      then R (ireg_param ir) :: loc_arguments_rec tys (ir + 1) fr ofs
-      else S Outgoing ofs ty :: loc_arguments_rec tys ir fr (ofs + 1)
+      then R (ireg_param ir) :: loc_arguments_hf tys (ir + 1) fr ofs
+      else S Outgoing ofs ty :: loc_arguments_hf tys ir fr (ofs + 1)
   | (Tfloat | Tany64) as ty :: tys =>
       if zlt fr 8
-      then R (freg_param fr) :: loc_arguments_rec tys ir (fr + 1) ofs
+      then R (freg_param fr) :: loc_arguments_hf tys ir (fr + 1) ofs
       else let ofs := align ofs 2 in
-           S Outgoing ofs ty :: loc_arguments_rec tys ir fr (ofs + 2)
+           S Outgoing ofs ty :: loc_arguments_hf tys ir fr (ofs + 2)
   | Tsingle :: tys =>
       if zlt fr 8
-      then R (freg_param fr) :: loc_arguments_rec tys ir (fr + 1) ofs
-      else S Outgoing ofs Tsingle :: loc_arguments_rec tys ir fr (ofs + 1)
+      then R (freg_param fr) :: loc_arguments_hf tys ir (fr + 1) ofs
+      else S Outgoing ofs Tsingle :: loc_arguments_hf tys ir fr (ofs + 1)
   | Tlong :: tys =>
       let ir := align ir 2 in
       if zlt ir 4
-      then R (ireg_param (ir + 1)) :: R (ireg_param ir) :: loc_arguments_rec tys (ir + 2) fr ofs
+      then R (ireg_param (ir + 1)) :: R (ireg_param ir) :: loc_arguments_hf tys (ir + 2) fr ofs
       else let ofs := align ofs 2 in
-          S Outgoing (ofs + 1) Tint :: S Outgoing ofs Tint :: loc_arguments_rec tys ir fr (ofs + 2)
+          S Outgoing (ofs + 1) Tint :: S Outgoing ofs Tint :: loc_arguments_hf tys ir fr (ofs + 2)
   end.
 
-(** For variable-argument functions, we use the default ARM EABI (not HF)
+(** For the "softfloat" configuration, as well as for variable-argument functions
+  in the "hardfloat" configuration, we use the default ARM EABI (not HF)
   calling conventions:
 - The first 4 integer arguments are passed in registers [R0] to [R3].
 - The first 2 long integer arguments are passed in an aligned pair of
@@ -329,73 +337,88 @@ Fixpoint loc_arguments_rec
 - Extra arguments are passed on the stack, in [Outgoing] slots, consecutively
   assigned (1 word for an integer or single argument, 2 words for a float
   or a long), starting at word offset 0.
-*)
 
-Fixpoint loc_arguments_vararg
+This convention is not quite that of the ARM EABI, whereas every float
+argument are passed in one or two integer registers.  Unfortunately,
+this does not fit the data model of CompCert.  In [PrintAsm.ml]
+we insert additional code around function calls and returns that moves
+data appropriately. *)
+
+Fixpoint loc_arguments_sf
      (tyl: list typ) (ofs: Z) {struct tyl} : list loc :=
   match tyl with
   | nil => nil
   | (Tint|Tany32) as ty :: tys =>
       (if zlt ofs 0 then R (ireg_param (ofs + 4)) else S Outgoing ofs ty)
-      :: loc_arguments_vararg tys (ofs + 1)
+      :: loc_arguments_sf tys (ofs + 1)
   | (Tfloat|Tany64) as ty :: tys =>
       let ofs := align ofs 2 in
       (if zlt ofs 0 then R (freg_param (ofs + 4)) else S Outgoing ofs ty)
-      :: loc_arguments_vararg tys (ofs + 2)
+      :: loc_arguments_sf tys (ofs + 2)
   | Tsingle :: tys =>
       (if zlt ofs 0 then R (freg_param (ofs + 4)) else S Outgoing ofs Tsingle)
-      :: loc_arguments_vararg tys (ofs + 1)
+      :: loc_arguments_sf tys (ofs + 1)
   | Tlong :: tys =>
       let ofs := align ofs 2 in
       (if zlt ofs 0 then R (ireg_param (ofs+1+4)) else S Outgoing (ofs+1) Tint)
       :: (if zlt ofs 0 then R (ireg_param (ofs+4)) else S Outgoing ofs Tint)
-      :: loc_arguments_vararg tys (ofs + 2)
+      :: loc_arguments_sf tys (ofs + 2)
   end.
 
 (** [loc_arguments s] returns the list of locations where to store arguments
   when calling a function with signature [s].  *)
 
 Definition loc_arguments (s: signature) : list loc :=
-  if s.(sig_cc).(cc_vararg)
-  then loc_arguments_vararg s.(sig_args) (-4)
-  else loc_arguments_rec s.(sig_args) 0 0 0.
+  match Archi.abi with
+  | Archi.Softfloat =>
+      loc_arguments_sf s.(sig_args) (-4)
+  | Archi.Hardfloat =>
+      if s.(sig_cc).(cc_vararg)
+      then loc_arguments_sf s.(sig_args) (-4)
+      else loc_arguments_hf s.(sig_args) 0 0 0
+  end.
 
 (** [size_arguments s] returns the number of [Outgoing] slots used
   to call a function with signature [s]. *)
 
-Fixpoint size_arguments_rec (tyl: list typ) (ir fr ofs: Z) {struct tyl} : Z :=
+Fixpoint size_arguments_hf (tyl: list typ) (ir fr ofs: Z) {struct tyl} : Z :=
   match tyl with
   | nil => ofs
   | (Tint|Tany32) :: tys =>
       if zlt ir 4
-      then size_arguments_rec tys (ir + 1) fr ofs
-      else size_arguments_rec tys ir fr (ofs + 1)
+      then size_arguments_hf tys (ir + 1) fr ofs
+      else size_arguments_hf tys ir fr (ofs + 1)
   | (Tfloat|Tany64) :: tys =>
       if zlt fr 8
-      then size_arguments_rec tys ir (fr + 1) ofs
-      else size_arguments_rec tys ir fr (align ofs 2 + 2)
+      then size_arguments_hf tys ir (fr + 1) ofs
+      else size_arguments_hf tys ir fr (align ofs 2 + 2)
   | Tsingle :: tys =>
       if zlt fr 8
-      then size_arguments_rec tys ir (fr + 1) ofs
-      else size_arguments_rec tys ir fr (ofs + 1)
+      then size_arguments_hf tys ir (fr + 1) ofs
+      else size_arguments_hf tys ir fr (ofs + 1)
   | Tlong :: tys =>
       let ir := align ir 2 in
       if zlt ir 4
-      then size_arguments_rec tys (ir + 2) fr ofs
-      else size_arguments_rec tys ir fr (align ofs 2 + 2)
+      then size_arguments_hf tys (ir + 2) fr ofs
+      else size_arguments_hf tys ir fr (align ofs 2 + 2)
   end.
 
-Fixpoint size_arguments_vararg (tyl: list typ) (ofs: Z) {struct tyl} : Z :=
+Fixpoint size_arguments_sf (tyl: list typ) (ofs: Z) {struct tyl} : Z :=
   match tyl with
   | nil => Zmax 0 ofs
-  | (Tint | Tsingle | Tany32) :: tys => size_arguments_vararg tys (ofs + 1)
-  | (Tfloat | Tlong | Tany64) :: tys => size_arguments_vararg tys (align ofs 2 + 2)
+  | (Tint | Tsingle | Tany32) :: tys => size_arguments_sf tys (ofs + 1)
+  | (Tfloat | Tlong | Tany64) :: tys => size_arguments_sf tys (align ofs 2 + 2)
   end.
 
 Definition size_arguments (s: signature) : Z :=
-  if s.(sig_cc).(cc_vararg)
-  then size_arguments_vararg s.(sig_args) (-4)
-  else size_arguments_rec s.(sig_args) 0 0 0.
+  match Archi.abi with
+  | Archi.Softfloat =>
+      size_arguments_sf s.(sig_args) (-4)
+  | Archi.Hardfloat =>
+      if s.(sig_cc).(cc_vararg)
+      then size_arguments_sf s.(sig_args) (-4)
+      else size_arguments_hf s.(sig_args) 0 0 0
+  end.
 
 (** Argument locations are either non-temporary registers or [Outgoing] 
   stack slots at nonnegative offsets. *)
@@ -423,9 +446,9 @@ Proof.
   simpl; auto.
 Qed.
 
-Remark loc_arguments_rec_charact:
+Remark loc_arguments_hf_charact:
   forall tyl ir fr ofs l,
-  In l (loc_arguments_rec tyl ir fr ofs) ->
+  In l (loc_arguments_hf tyl ir fr ofs) ->
   match l with
   | R r => In r int_param_regs \/ In r float_param_regs
   | S Outgoing ofs' ty => ofs' >= ofs /\ ty <> Tlong
@@ -447,7 +470,7 @@ Proof.
   {
     intros. destruct l; auto. destruct sl; auto. intuition omega.
   }
-  induction tyl; simpl loc_arguments_rec; intros.
+  induction tyl; simpl loc_arguments_hf; intros.
   elim H.
   destruct a.
 - (* int *)
@@ -494,9 +517,9 @@ Proof.
   apply Zle_trans with (align ofs 2). apply align_le; omega. omega.
 Qed.
 
-Remark loc_arguments_vararg_charact:
+Remark loc_arguments_sf_charact:
   forall tyl ofs l,
-  In l (loc_arguments_vararg tyl ofs) ->
+  In l (loc_arguments_sf tyl ofs) ->
   match l with
   | R r => In r int_param_regs \/ In r float_param_regs
   | S Outgoing ofs' ty => ofs' >= Zmax 0 ofs /\ ty <> Tlong
@@ -518,7 +541,7 @@ Proof.
   {
     intros. destruct l; auto. destruct sl; auto. intuition xomega.
   }
-  induction tyl; simpl loc_arguments_vararg; intros.
+  induction tyl; simpl loc_arguments_sf; intros.
   elim H.
   destruct a.
 - (* int *)
@@ -578,20 +601,20 @@ Proof.
   {
     intros. elim H0; simpl; ElimOrEq; OrEq.
   }
-  red. destruct (cc_vararg (sig_cc s)). 
-  exploit loc_arguments_vararg_charact; eauto.
-  destruct l; auto.
-  exploit loc_arguments_rec_charact; eauto.
-  destruct l; auto.
+  assert (In l (loc_arguments_sf (sig_args s) (-4)) -> loc_argument_acceptable l).
+  { intros. red. exploit loc_arguments_sf_charact; eauto. destruct l; auto. }
+  assert (In l (loc_arguments_hf (sig_args s) 0 0 0) -> loc_argument_acceptable l).
+  { intros. red. exploit loc_arguments_hf_charact; eauto. destruct l; auto. }
+  destruct Archi.abi; [ | destruct (cc_vararg (sig_cc s)) ]; auto.
 Qed.
 
 Hint Resolve loc_arguments_acceptable: locs.
 
 (** The offsets of [Outgoing] arguments are below [size_arguments s]. *)
 
-Remark size_arguments_rec_above:
+Remark size_arguments_hf_above:
   forall tyl ir fr ofs0,
-  ofs0 <= size_arguments_rec tyl ir fr ofs0.
+  ofs0 <= size_arguments_hf tyl ir fr ofs0.
 Proof.
   induction tyl; simpl; intros.
   omega.
@@ -612,9 +635,9 @@ Proof.
   apply Zle_trans with (align ofs0 2 + 2); auto; omega.
 Qed.
 
-Remark size_arguments_vararg_above:
+Remark size_arguments_sf_above:
   forall tyl ofs0,
-  Zmax 0 ofs0 <= size_arguments_vararg tyl ofs0.
+  Zmax 0 ofs0 <= size_arguments_sf tyl ofs0.
 Proof.
   induction tyl; simpl; intros.
   omega.
@@ -630,15 +653,18 @@ Qed.
 Lemma size_arguments_above:
   forall s, size_arguments s >= 0.
 Proof.
-  intros; unfold size_arguments. destruct (cc_vararg (sig_cc s)).
-  apply Zle_ge. change 0 with (Zmax 0 (-4)). apply size_arguments_vararg_above.  
-  apply Zle_ge. apply size_arguments_rec_above.
+  intros; unfold size_arguments. apply Zle_ge.
+  assert (0 <= size_arguments_sf (sig_args s) (-4)).
+  { change 0 with (Zmax 0 (-4)). apply size_arguments_sf_above. }
+  assert (0 <= size_arguments_hf (sig_args s) 0 0 0).
+  { apply size_arguments_hf_above. }
+  destruct Archi.abi; [ | destruct (cc_vararg (sig_cc s)) ]; auto.
 Qed.
 
-Lemma loc_arguments_rec_bounded:
+Lemma loc_arguments_hf_bounded:
   forall ofs ty tyl ir fr ofs0,
-  In (S Outgoing ofs ty) (loc_arguments_rec tyl ir fr ofs0) ->
-  ofs + typesize ty <= size_arguments_rec tyl ir fr ofs0.
+  In (S Outgoing ofs ty) (loc_arguments_hf tyl ir fr ofs0) ->
+  ofs + typesize ty <= size_arguments_hf tyl ir fr ofs0.
 Proof.
   induction tyl; simpl; intros.
   elim H.
@@ -647,77 +673,77 @@ Proof.
   destruct (zlt ir 4); destruct H.
   discriminate.
   eauto.
-  inv H. apply size_arguments_rec_above. 
+  inv H. apply size_arguments_hf_above. 
   eauto.
 - (* float *)
   destruct (zlt fr 8); destruct H.
   discriminate.
   eauto. 
-  inv H. apply size_arguments_rec_above. 
+  inv H. apply size_arguments_hf_above. 
   eauto.
 - (* long *)
   destruct (zlt (align ir 2) 4).
   destruct H. discriminate. destruct H. discriminate. eauto. 
   destruct H. inv H.
-  rewrite <- Zplus_assoc. simpl. apply size_arguments_rec_above.
+  rewrite <- Zplus_assoc. simpl. apply size_arguments_hf_above.
   destruct H. inv H.
-  eapply Zle_trans. 2: apply size_arguments_rec_above. simpl; omega.
+  eapply Zle_trans. 2: apply size_arguments_hf_above. simpl; omega.
   eauto.
 - (* float *)
   destruct (zlt fr 8); destruct H.
   discriminate.
   eauto.
-  inv H. apply size_arguments_rec_above.
+  inv H. apply size_arguments_hf_above.
   eauto.
 - (* any32 *)
   destruct (zlt ir 4); destruct H.
   discriminate.
   eauto.
-  inv H. apply size_arguments_rec_above. 
+  inv H. apply size_arguments_hf_above. 
   eauto.
 - (* any64 *)
   destruct (zlt fr 8); destruct H.
   discriminate.
   eauto. 
-  inv H. apply size_arguments_rec_above. 
+  inv H. apply size_arguments_hf_above. 
   eauto.
 Qed.
 
-Lemma loc_arguments_vararg_bounded:
+Lemma loc_arguments_sf_bounded:
   forall ofs ty tyl ofs0,
-  In (S Outgoing ofs ty) (loc_arguments_vararg tyl ofs0) ->
-  Zmax 0 (ofs + typesize ty) <= size_arguments_vararg tyl ofs0.
+  In (S Outgoing ofs ty) (loc_arguments_sf tyl ofs0) ->
+  Zmax 0 (ofs + typesize ty) <= size_arguments_sf tyl ofs0.
 Proof.
   induction tyl; simpl; intros.
   elim H.
   destruct a.
 - (* int *)
   destruct H. 
-  destruct (zlt ofs0 0); inv H. apply size_arguments_vararg_above. 
+  destruct (zlt ofs0 0); inv H. apply size_arguments_sf_above. 
   eauto.
 - (* float *)
   destruct H.
-  destruct (zlt (align ofs0 2) 0); inv H. apply size_arguments_vararg_above.
+  destruct (zlt (align ofs0 2) 0); inv H. apply size_arguments_sf_above.
   eauto.
 - (* long *)
   destruct H. 
   destruct (zlt (align ofs0 2) 0); inv H.
-  rewrite <- Zplus_assoc. simpl. apply size_arguments_vararg_above.
+  rewrite <- Zplus_assoc. simpl. apply size_arguments_sf_above.
   destruct H. 
   destruct (zlt (align ofs0 2) 0); inv H.
-  eapply Zle_trans. 2: apply size_arguments_vararg_above. simpl; xomega.
+  eapply Zle_trans. 2: apply size_arguments_sf_above. simpl; xomega.
   eauto.
 - (* float *)
   destruct H. 
-  destruct (zlt ofs0 0); inv H. apply size_arguments_vararg_above. 
+  destruct (zlt ofs0 0); inv H. apply size_arguments_sf_above. 
   eauto.
 - (* any32 *)
   destruct H. 
-  destruct (zlt ofs0 0); inv H. apply size_arguments_vararg_above. 
+  destruct (zlt ofs0 0); inv H. apply size_arguments_sf_above. 
   eauto.
 - (* any64 *)
   destruct H.
-  destruct (zlt (align ofs0 2) 0); inv H. apply size_arguments_vararg_above.
+  destruct (zlt (align ofs0 2) 0); inv H. apply size_arguments_sf_above.
   eauto.
 Qed.
 
@@ -727,7 +753,18 @@ Lemma loc_arguments_bounded:
   ofs + typesize ty <= size_arguments s.
 Proof.
   unfold loc_arguments, size_arguments; intros.
-  destruct (cc_vararg (sig_cc s)).
-  eapply Zle_trans. 2: eapply loc_arguments_vararg_bounded; eauto. xomega. 
-  eapply loc_arguments_rec_bounded; eauto.
+  assert (In (S Outgoing ofs ty) (loc_arguments_sf (sig_args s) (-4)) ->
+          ofs + typesize ty <= size_arguments_sf (sig_args s) (-4)).
+  { intros. eapply Zle_trans. 2: eapply loc_arguments_sf_bounded; eauto. xomega. }
+  assert (In (S Outgoing ofs ty) (loc_arguments_hf (sig_args s) 0 0 0) ->
+          ofs + typesize ty <= size_arguments_hf (sig_args s) 0 0 0).
+  { intros. eapply loc_arguments_hf_bounded; eauto. }
+  destruct Archi.abi; [ | destruct (cc_vararg (sig_cc s)) ]; eauto.
+Qed.
+
+Lemma loc_arguments_main:
+  loc_arguments signature_main = nil.
+Proof.
+  unfold loc_arguments. 
+  destruct Archi.abi; reflexivity.
 Qed.
diff --git a/arm/eabi/Stacklayout.v b/arm/Stacklayout.v
index 7694dcf..7694dcf 100644
--- a/arm/eabi/Stacklayout.v
+++ b/arm/Stacklayout.v
diff --git a/arm/eabi/Conventions1.v b/arm/eabi/Conventions1.v
deleted file mode 100644
index c26d29e..0000000
--- a/arm/eabi/Conventions1.v
+++ /dev/null
@@ -1,509 +0,0 @@
-(* *********************************************************************)
-(*                                                                     *)
-(*              The Compcert verified compiler                         *)
-(*                                                                     *)
-(*          Xavier Leroy, INRIA Paris-Rocquencourt                     *)
-(*                                                                     *)
-(*  Copyright Institut National de Recherche en Informatique et en     *)
-(*  Automatique.  All rights reserved.  This file is distributed       *)
-(*  under the terms of the INRIA Non-Commercial License Agreement.     *)
-(*                                                                     *)
-(* *********************************************************************)
-
-(** Function calling conventions and other conventions regarding the use of 
-    machine registers and stack slots. *)
-
-Require Import Coqlib.
-Require Import AST.
-Require Import Events.
-Require Import Locations.
-
-(** * Classification of machine registers *)
-
-(** Machine registers (type [mreg] in module [Locations]) are divided in
-  the following groups:
-- Temporaries used for spilling, reloading, and parallel move operations.
-- Allocatable registers, that can be assigned to RTL pseudo-registers.
-  These are further divided into:
--- Callee-save registers, whose value is preserved across a function call.
--- Caller-save registers that can be modified during a function call.
-
-  We follow the PowerPC application binary interface (ABI) in our choice
-  of callee- and caller-save registers.
-*)
-
-Definition int_caller_save_regs :=
-  R0 :: R1 :: R2 :: R3 :: R12 :: nil.
-
-Definition float_caller_save_regs :=
-  F0 :: F1 :: F2 :: F3 :: F4 :: F5 :: F6 :: F7 :: nil.
-
-Definition int_callee_save_regs :=
-  R4 :: R5 :: R6 :: R7 :: R8 :: R9 :: R10 :: R11 :: nil.
-
-Definition float_callee_save_regs :=
-  F8 :: F9 :: F10 :: F11 :: F12 :: F13 :: F14 :: F15 :: nil.
-
-Definition destroyed_at_call :=
-  int_caller_save_regs ++ float_caller_save_regs.
-
-Definition dummy_int_reg := R0.     (**r Used in [Coloring]. *)
-Definition dummy_float_reg := F0.   (**r Used in [Coloring]. *)
-
-(** The [index_int_callee_save] and [index_float_callee_save] associate
-  a unique positive integer to callee-save registers.  This integer is
-  used in [Stacking] to determine where to save these registers in
-  the activation record if they are used by the current function. *)
-
-Definition index_int_callee_save (r: mreg) :=
-  match r with
-  | R4 => 0  | R5 => 1  | R6 => 2  | R7 => 3
-  | R8 => 4  | R9 => 5  | R10 => 6 | R11 => 7
-  | _ => -1
-  end.
-
-Definition index_float_callee_save (r: mreg) :=
-  match r with
-  | F8 => 0  | F9 => 1  | F10 => 2  | F11 => 3
-  | F12 => 4  | F13 => 5  | F14 => 6  | F15 => 7
-  | _ => -1
-  end.
-
-Ltac ElimOrEq :=
-  match goal with
-  |  |- (?x = ?y) \/ _ -> _ =>
-       let H := fresh in
-       (intro H; elim H; clear H;
-        [intro H; rewrite <- H; clear H | ElimOrEq])
-  |  |- False -> _ =>
-       let H := fresh in (intro H; contradiction)
-  end.
-
-Ltac OrEq :=
-  match goal with
-  | |- (?x = ?x) \/ _ => left; reflexivity
-  | |- (?x = ?y) \/ _ => right; OrEq
-  | |- False => fail
-  end.
-
-Ltac NotOrEq :=
-  match goal with
-  | |- (?x = ?y) \/ _ -> False =>
-       let H := fresh in (
-       intro H; elim H; clear H; [intro; discriminate | NotOrEq])
-  | |- False -> False =>
-       contradiction
-  end.
-
-Lemma index_int_callee_save_pos:
-  forall r, In r int_callee_save_regs -> index_int_callee_save r >= 0.
-Proof.
-  intro r. simpl; ElimOrEq; unfold index_int_callee_save; omega.
-Qed.
-
-Lemma index_float_callee_save_pos:
-  forall r, In r float_callee_save_regs -> index_float_callee_save r >= 0.
-Proof.
-  intro r. simpl; ElimOrEq; unfold index_float_callee_save; omega.
-Qed.
-
-Lemma index_int_callee_save_pos2:
-  forall r, index_int_callee_save r >= 0 -> In r int_callee_save_regs.
-Proof.
-  destruct r; simpl; intro; omegaContradiction || OrEq.
-Qed.
-
-Lemma index_float_callee_save_pos2:
-  forall r, index_float_callee_save r >= 0 -> In r float_callee_save_regs.
-Proof.
-  destruct r; simpl; intro; omegaContradiction || OrEq.
-Qed.
-
-Lemma index_int_callee_save_inj:
-  forall r1 r2, 
-  In r1 int_callee_save_regs ->
-  In r2 int_callee_save_regs ->
-  r1 <> r2 ->
-  index_int_callee_save r1 <> index_int_callee_save r2.
-Proof.
-  intros r1 r2. 
-  simpl; ElimOrEq; ElimOrEq; unfold index_int_callee_save;
-  intros; congruence.
-Qed.
-
-Lemma index_float_callee_save_inj:
-  forall r1 r2, 
-  In r1 float_callee_save_regs ->
-  In r2 float_callee_save_regs ->
-  r1 <> r2 ->
-  index_float_callee_save r1 <> index_float_callee_save r2.
-Proof.
-  intros r1 r2. 
-  simpl; ElimOrEq; ElimOrEq; unfold index_float_callee_save;
-  intros; congruence.
-Qed.
-
-(** The following lemmas show that
-    (temporaries, destroyed at call, integer callee-save, float callee-save)
-    is a partition of the set of machine registers. *)
-
-Lemma int_float_callee_save_disjoint:
-  list_disjoint int_callee_save_regs float_callee_save_regs.
-Proof.
-  red; intros r1 r2. simpl; ElimOrEq; ElimOrEq; discriminate.
-Qed.
-
-Lemma register_classification:
-  forall r, 
-  In r destroyed_at_call \/ In r int_callee_save_regs \/ In r float_callee_save_regs.
-Proof.
-  destruct r; 
-  try (left; simpl; OrEq);
-  try (right; left; simpl; OrEq);
-  try (right; right; simpl; OrEq).
-Qed.
-
-
-Lemma int_callee_save_not_destroyed:
-  forall r, 
-    In r destroyed_at_call -> In r int_callee_save_regs -> False.
-Proof.
-  intros. revert H0 H. simpl. ElimOrEq; NotOrEq.
-Qed.
-
-Lemma float_callee_save_not_destroyed:
-  forall r, 
-    In r destroyed_at_call -> In r float_callee_save_regs -> False.
-Proof.
-  intros. revert H0 H. simpl. ElimOrEq; NotOrEq.
-Qed.
-
-Lemma int_callee_save_type:
-  forall r, In r int_callee_save_regs -> mreg_type r = Tany32.
-Proof.
-  intro. simpl; ElimOrEq; reflexivity.
-Qed.
-
-Lemma float_callee_save_type:
-  forall r, In r float_callee_save_regs -> mreg_type r = Tany64.
-Proof.
-  intro. simpl; ElimOrEq; reflexivity.
-Qed.
-
-Ltac NoRepet :=
-  match goal with
-  | |- list_norepet nil =>
-      apply list_norepet_nil
-  | |- list_norepet (?a :: ?b) =>
-      apply list_norepet_cons; [simpl; intuition discriminate | NoRepet]
-  end.
-
-Lemma int_callee_save_norepet:
-  list_norepet int_callee_save_regs.
-Proof.
-  unfold int_callee_save_regs; NoRepet.
-Qed.
-
-Lemma float_callee_save_norepet:
-  list_norepet float_callee_save_regs.
-Proof.
-  unfold float_callee_save_regs; NoRepet.
-Qed.
-
-(** * Function calling conventions *)
-
-(** The functions in this section determine the locations (machine registers
-  and stack slots) used to communicate arguments and results between the
-  caller and the callee during function calls.  These locations are functions
-  of the signature of the function and of the call instruction.  
-  Agreement between the caller and the callee on the locations to use
-  is guaranteed by our dynamic semantics for Cminor and RTL, which demand 
-  that the signature of the call instruction is identical to that of the
-  called function.
-
-  Calling conventions are largely arbitrary: they must respect the properties
-  proved in this section (such as no overlapping between the locations
-  of function arguments), but this leaves much liberty in choosing actual
-  locations.  *)
-
-(** ** Location of function result *)
-
-(** The result value of a function is passed back to the caller in
-  registers [R0] or [F0] or [R0,R1], depending on the type of the
-  returned value.  We treat a function without result as a function
-  with one integer result. *)
-
-Definition loc_result (s: signature) : list mreg :=
-  match s.(sig_res) with
-  | None => R0 :: nil
-  | Some (Tint | Tany32) => R0 :: nil
-  | Some (Tfloat | Tsingle | Tany64) => F0 :: nil
-  | Some Tlong => R1 :: R0 :: nil
-  end.
-
-(** The result registers have types compatible with that given in the signature. *)
-
-Lemma loc_result_type:
-  forall sig,
-  subtype_list (proj_sig_res' sig) (map mreg_type (loc_result sig)) = true.
-Proof.
-  intros. unfold proj_sig_res', loc_result. destruct (sig_res sig) as [[]|]; auto.
-Qed.
-
-(** The result locations are caller-save registers *)
-
-Lemma loc_result_caller_save:
-  forall (s: signature) (r: mreg), 
-  In r (loc_result s) -> In r destroyed_at_call.
-Proof.
-  intros.
-  assert (r = R0 \/ r = R1 \/ r = F0).
-    unfold loc_result in H. destruct (sig_res s); [destruct t|idtac]; simpl in H; intuition.
-  destruct H0 as [A | [A | A]]; subst r; simpl; OrEq.
-Qed.
-
-(** ** Location of function arguments *)
-
-(** We use the following calling conventions, adapted from the ARM EABI:
-- The first 4 integer arguments are passed in registers [R0] to [R3].
-- The first 2 double float arguments are passed in registers [F0] and [F2].
-- The first 4 single float arguments are passed in registers [F0] to [F3].
-- The first 2 long integer arguments are passed in an aligned pair of
-  two integer registers.
-- Each double argument passed in a float register ``consumes'' an aligned pair
-  of two integer registers.
-- Each single argument passed in a float register ``consumes'' an integer
-  register.
-- Extra arguments are passed on the stack, in [Outgoing] slots, consecutively
-  assigned (1 word for an integer or single argument, 2 words for a double
-  or a long), starting at word offset 0.
-
-This convention is not quite that of the ARM EABI, whereas every float
-argument are passed in one or two integer registers.  Unfortunately,
-this does not fit the data model of CompCert.  In [PrintAsm.ml]
-we insert additional code around function calls and returns that moves
-data appropriately. *)
-
-Definition ireg_param (n: Z) : mreg :=
-  if zeq n (-4) then R0
-  else if zeq n (-3) then R1
-  else if zeq n (-2) then R2
-  else R3.
-
-Definition freg_param (n: Z) : mreg :=
-  if zeq n (-4) then F0 else F2.
-
-Definition sreg_param (n: Z) : mreg :=
-  if zeq n (-4) then F0
-  else if zeq n (-3) then F1
-  else if zeq n (-2) then F2
-  else F3.
-
-Fixpoint loc_arguments_rec (tyl: list typ) (ofs: Z) {struct tyl} : list loc :=
-  match tyl with
-  | nil => nil
-  | (Tint | Tany32) as ty :: tys =>
-      (if zle 0 ofs then S Outgoing ofs ty else R (ireg_param ofs))
-      :: loc_arguments_rec tys (ofs + 1)
-  | (Tfloat | Tany64) as ty :: tys =>
-      let ofs := align ofs 2 in
-      (if zle 0 ofs then S Outgoing ofs ty else R (freg_param ofs))
-      :: loc_arguments_rec tys (ofs + 2)
-  | Tsingle :: tys =>
-      (if zle 0 ofs then S Outgoing ofs Tsingle else R (sreg_param ofs))
-      :: loc_arguments_rec tys (ofs + 1)
-  | Tlong :: tys =>
-      let ofs := align ofs 2 in
-      (if zle 0 ofs then S Outgoing (ofs + 1) Tint else R (ireg_param (ofs + 1)))
-      :: (if zle 0 ofs then S Outgoing ofs Tint else R (ireg_param ofs))
-      :: loc_arguments_rec tys (ofs + 2)
-  end.
-
-(** [loc_arguments s] returns the list of locations where to store arguments
-  when calling a function with signature [s].  *)
-
-Definition loc_arguments (s: signature) : list loc :=
-  loc_arguments_rec s.(sig_args) (-4).
-
-(** [size_arguments s] returns the number of [Outgoing] slots used
-  to call a function with signature [s]. *)
-
-Fixpoint size_arguments_rec (tyl: list typ) (ofs: Z) {struct tyl} : Z :=
-  match tyl with
-  | nil => ofs
-  | (Tint | Tsingle | Tany32) :: tys => size_arguments_rec tys (ofs + 1)
-  | (Tfloat | Tlong | Tany64) :: tys => size_arguments_rec tys (align ofs 2 + 2)
-  end.
-
-Definition size_arguments (s: signature) : Z :=
-  Zmax 0 (size_arguments_rec s.(sig_args) (-4)).
-
-(** Argument locations are either non-temporary registers or [Outgoing] 
-  stack slots at nonnegative offsets. *)
-
-Definition loc_argument_acceptable (l: loc) : Prop :=
-  match l with
-  | R r => In r destroyed_at_call
-  | S Outgoing ofs ty => ofs >= 0 /\ ty <> Tlong
-  | _ => False
-  end.
-
-Remark ireg_param_caller_save:
-  forall n, In (ireg_param n) destroyed_at_call.
-Proof.
-  unfold ireg_param; intros.
-  destruct (zeq n (-4)). simpl; auto. 
-  destruct (zeq n (-3)). simpl; auto. 
-  destruct (zeq n (-2)); simpl; auto.
-Qed.
-
-Remark freg_param_caller_save:
-  forall n, In (freg_param n) destroyed_at_call.
-Proof.
-  unfold freg_param; intros. destruct (zeq n (-4)); simpl; OrEq.
-Qed.
-
-Remark sreg_param_caller_save:
-  forall n, In (sreg_param n) destroyed_at_call.
-Proof.
-  unfold sreg_param; intros.
-  destruct (zeq n (-4)). simpl; tauto. 
-  destruct (zeq n (-3)). simpl; tauto. 
-  destruct (zeq n (-2)); simpl; tauto.
-Qed.
-
-Remark loc_arguments_rec_charact:
-  forall tyl ofs l,
-  In l (loc_arguments_rec tyl ofs) ->
-  match l with
-  | R r => In r destroyed_at_call
-  | S Outgoing ofs' ty => ofs' >= 0 /\ ofs <= ofs' /\ ty <> Tlong
-  | S _ _ _ => False
-  end.
-Proof.
-  induction tyl; simpl loc_arguments_rec; intros.
-  elim H.
-  destruct a.
-- (* Tint *)
-  destruct H.
-  subst l. destruct (zle 0 ofs).
-  split. omega. split. omega. congruence.
-  apply ireg_param_caller_save.
-  exploit IHtyl; eauto. destruct l; auto. destruct sl; auto. intuition omega.
-- (* Tfloat *)
-  assert (ofs <= align ofs 2) by (apply align_le; omega).
-  destruct H.
-  subst l. destruct (zle 0 (align ofs 2)).
-  split. omega. split. auto. congruence.
-  apply freg_param_caller_save.
-  exploit IHtyl; eauto. destruct l; auto. destruct sl; auto. intuition omega.
-- (* Tlong *)
-  assert (ofs <= align ofs 2) by (apply align_le; omega).
-  destruct H.
-  subst l. destruct (zle 0 (align ofs 2)).
-  split. omega. split. omega. congruence.
-  apply ireg_param_caller_save.
-  destruct H.
-  subst l. destruct (zle 0 (align ofs 2)).
-  split. omega. split. omega. congruence.
-  apply ireg_param_caller_save.
-  exploit IHtyl; eauto. destruct l; auto. destruct sl; auto. intuition omega.
-- (* Tsingle *)
-  destruct H.
-  subst l. destruct (zle 0 ofs).
-  split. omega. split. omega. congruence.
-  apply sreg_param_caller_save.
-  exploit IHtyl; eauto. destruct l; auto. destruct sl; auto. intuition omega.
-- (* Tany32 *)
-  destruct H.
-  subst l. destruct (zle 0 ofs).
-  split. omega. split. omega. congruence.
-  apply ireg_param_caller_save.
-  exploit IHtyl; eauto. destruct l; auto. destruct sl; auto. intuition omega.
-- (* Tany64 *)
-  assert (ofs <= align ofs 2) by (apply align_le; omega).
-  destruct H.
-  subst l. destruct (zle 0 (align ofs 2)).
-  split. omega. split. auto. congruence.
-  apply freg_param_caller_save.
-  exploit IHtyl; eauto. destruct l; auto. destruct sl; auto. intuition omega.
-Qed.
-
-Lemma loc_arguments_acceptable:
-  forall (s: signature) (r: loc),
-  In r (loc_arguments s) -> loc_argument_acceptable r.
-Proof.
-  unfold loc_arguments, loc_argument_acceptable; intros.
-  generalize (loc_arguments_rec_charact _ _ _ H).
-  destruct r; auto.
-  destruct sl; auto.
-  tauto.
-Qed.
-Hint Resolve loc_arguments_acceptable: locs.
-
-(** The offsets of [Outgoing] arguments are below [size_arguments s]. *)
-
-Remark size_arguments_rec_above:
-  forall tyl ofs,
-  ofs <= size_arguments_rec tyl ofs.
-Proof.
-  induction tyl; simpl; intros.
-  omega.
-  destruct a.
-  apply Zle_trans with (ofs + 1); auto; omega.
-  assert (ofs <= align ofs 2) by (apply align_le; omega).
-  apply Zle_trans with (align ofs 2 + 2); auto; omega.
-  assert (ofs <= align ofs 2) by (apply align_le; omega).
-  apply Zle_trans with (align ofs 2 + 2); auto; omega.
-  apply Zle_trans with (ofs + 1); auto; omega.
-  apply Zle_trans with (ofs + 1); auto; omega.
-  assert (ofs <= align ofs 2) by (apply align_le; omega).
-  apply Zle_trans with (align ofs 2 + 2); auto; omega.
-Qed.
-
-Lemma size_arguments_above:
-  forall s, size_arguments s >= 0.
-Proof.
-  intros; unfold size_arguments. apply Zle_ge. apply Zmax1.
-Qed.
-
-Lemma loc_arguments_bounded:
-  forall (s: signature) (ofs: Z) (ty: typ),
-  In (S Outgoing ofs ty) (loc_arguments s) ->
-  ofs + typesize ty <= size_arguments s.
-Proof.
-  intros.
-  assert (forall tyl ofs0,
-          0 <= ofs0 ->
-          ofs0 <= Zmax 0 (size_arguments_rec tyl ofs0)).
-  {
-    intros. generalize (size_arguments_rec_above tyl ofs0). intros.
-    rewrite Zmax_spec. rewrite zlt_false. auto. omega.
-  } 
-  assert (forall tyl ofs0,
-    In (S Outgoing ofs ty) (loc_arguments_rec tyl ofs0) ->
-    ofs + typesize ty <= Zmax 0 (size_arguments_rec tyl ofs0)).
-  {
-    induction tyl; simpl; intros.
-    elim H1.
-    destruct a.
-  - (* Tint *)
-    destruct H1; auto. destruct (zle 0 ofs0); inv H1. apply H0. omega. 
-  - (* Tfloat *)
-    destruct H1; auto. destruct (zle 0 (align ofs0 2)); inv H1. apply H0. omega.
-  - (* Tlong *)
-    destruct H1.
-    destruct (zle 0 (align ofs0 2)); inv H1.
-    eapply Zle_trans. 2: apply H0. simpl typesize; omega. omega. 
-    destruct H1; auto.
-    destruct (zle 0 (align ofs0 2)); inv H1.
-    eapply Zle_trans. 2: apply H0. simpl typesize; omega. omega.
-  - (* Tsingle *)
-    destruct H1; auto. destruct (zle 0 ofs0); inv H1. apply H0. omega. 
-  - (* Tany32 *)
-    destruct H1; auto. destruct (zle 0 ofs0); inv H1. apply H0. omega. 
-  - (* Tany64 *)
-    destruct H1; auto. destruct (zle 0 (align ofs0 2)); inv H1. apply H0. omega.
-  }
-  unfold size_arguments. apply H1. auto.  
-Qed.
diff --git a/arm/extractionMachdep.v b/arm/extractionMachdep.v
index f6e17ba..0c9b705 100644
--- a/arm/extractionMachdep.v
+++ b/arm/extractionMachdep.v
@@ -16,3 +16,11 @@
 Extract Constant Asm.ireg_eq => "fun (x: ireg) (y: ireg) -> x = y".
 Extract Constant Asm.freg_eq => "fun (x: freg) (y: freg) -> x = y".
 Extract Constant Asm.preg_eq => "fun (x: preg) (y: preg) -> x = y".
+
+(* Choice of calling conventions *)
+Extract Constant Archi.abi =>
+  "begin match Configuration.variant with
+   | ""eabi"" -> Softfloat
+   | ""hardfloat"" -> Hardfloat
+   | _ -> assert false
+   end".
diff --git a/arm/hardfloat/Stacklayout.v b/arm/hardfloat/Stacklayout.v
deleted file mode 100644
index 7694dcf..0000000
--- a/arm/hardfloat/Stacklayout.v
+++ /dev/null
@@ -1,132 +0,0 @@
-(* *********************************************************************)
-(*                                                                     *)
-(*              The Compcert verified compiler                         *)
-(*                                                                     *)
-(*          Xavier Leroy, INRIA Paris-Rocquencourt                     *)
-(*                                                                     *)
-(*  Copyright Institut National de Recherche en Informatique et en     *)
-(*  Automatique.  All rights reserved.  This file is distributed       *)
-(*  under the terms of the INRIA Non-Commercial License Agreement.     *)
-(*                                                                     *)
-(* *********************************************************************)
-
-(** Machine- and ABI-dependent layout information for activation records. *)
-
-Require Import Coqlib.
-Require Import Bounds.
-
-(** The general shape of activation records is as follows,
-  from bottom (lowest offsets) to top:
-- Space for outgoing arguments to function calls.
-- Local stack slots.
-- Saved values of integer callee-save registers used by the function.
-- Saved values of float callee-save registers used by the function.
-- Saved return address into caller.
-- Pointer to activation record of the caller.
-- Space for the stack-allocated data declared in Cminor.
-
-The [frame_env] compilation environment records the positions of
-the boundaries between areas in the frame part.
-*)
-
-Definition fe_ofs_arg := 0.
-
-Record frame_env : Type := mk_frame_env {
-  fe_size: Z;
-  fe_ofs_link: Z;
-  fe_ofs_retaddr: Z;
-  fe_ofs_local: Z;
-  fe_ofs_int_callee_save: Z;
-  fe_num_int_callee_save: Z;
-  fe_ofs_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
-  function. *)
-
-Definition make_env (b: bounds) :=
-  let ol := align (4 * b.(bound_outgoing)) 8 in    (* locals *)
-  let oics := ol + 4 * b.(bound_local) in (* integer callee-saves *)
-  let oendi := oics + 4 * b.(bound_int_callee_save) in
-  let ofcs := align oendi 8 in       (* float callee-saves *)
-  let ora := ofcs + 8 * b.(bound_float_callee_save) in (* retaddr *)
-  let olink := ora + 4 in (* back link *)
-  let ostkdata := olink + 4 in (* stack data *)
-  let sz := align (ostkdata + b.(bound_stack_data)) 8 in
-  mk_frame_env sz olink ora ol
-                  oics b.(bound_int_callee_save)
-                  ofcs b.(bound_float_callee_save)
-                  ostkdata.
-
-(** Separation property *)
-
-Remark frame_env_separated:
-  forall b,
-  let fe := make_env b in
-  0 <= fe_ofs_arg
-  /\ fe_ofs_arg + 4 * b.(bound_outgoing) <= fe.(fe_ofs_local)
-  /\ fe.(fe_ofs_local) + 4 * b.(bound_local) <= fe.(fe_ofs_int_callee_save)
-  /\ fe.(fe_ofs_int_callee_save) + 4 * b.(bound_int_callee_save) <= 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.
-  generalize (align_le (4 * bound_outgoing b) 8 (refl_equal)).
-  generalize (align_le (fe_ofs_int_callee_save fe + 4 * b.(bound_int_callee_save)) 8 (refl_equal _)).
-  generalize (align_le (fe_stack_data fe + b.(bound_stack_data)) 8 (refl_equal)).
-  unfold fe, make_env, fe_size, fe_ofs_link, fe_ofs_retaddr,
-    fe_ofs_local, fe_ofs_int_callee_save, fe_num_int_callee_save,
-    fe_ofs_float_callee_save, fe_num_float_callee_save,
-    fe_stack_data, fe_ofs_arg.
-  intros.
-  generalize (bound_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))
-  /\ (8 | fe.(fe_ofs_local))
-  /\ (4 | fe.(fe_ofs_int_callee_save))
-  /\ (8 | fe.(fe_ofs_float_callee_save))
-  /\ (4 | fe.(fe_ofs_retaddr))
-  /\ (8 | fe.(fe_stack_data))
-  /\ (8 | fe.(fe_size)).
-Proof.
-  intros.
-  unfold fe, make_env, fe_size, fe_ofs_link, fe_ofs_retaddr,
-    fe_ofs_local, fe_ofs_int_callee_save, fe_num_int_callee_save,
-    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 := align x1 8).
-  assert (8 | x2). apply align_divides. omega. 
-  set (x3 := x2 + 4 * bound_local b).
-  assert (4 | x3). apply Zdivide_plus_r. apply Zdivides_trans with 8; auto. exists 2; auto.
-  exists (bound_local b); ring.
-  set (x4 := align (x3 + 4 * bound_int_callee_save b) 8).
-  assert (8 | x4). apply align_divides. omega.
-  set (x5 := x4 + 8 * bound_float_callee_save b).
-  assert (8 | x5). apply Zdivide_plus_r; auto. exists (bound_float_callee_save b); ring.
-  assert (4 | x5). apply Zdivides_trans with 8; auto. exists 2; auto.
-  set (x6 := x5 + 4). 
-  assert (4 | x6). apply Zdivide_plus_r; auto. exists 1; auto.
-  set (x7 := x6 + 4).
-  assert (8 | x7). unfold x7, x6. replace (x5 + 4 + 4) with (x5 + 8) by omega. 
-  apply Zdivide_plus_r; auto. exists 1; auto.
-  set (x8 := align (x7 + bound_stack_data b) 8).
-  assert (8 | x8). apply align_divides. omega.
-  tauto.
-Qed.