From 51e8bc524d570439f868ec0bdbf718cb53ca7669 Mon Sep 17 00:00:00 2001
From: xleroy <xleroy@fca1b0fc-160b-0410-b1d3-a4f43f01ea2e>
Date: Mon, 30 Dec 2013 16:37:05 +0000
Subject: Ctypes.sizeof ty = 0 for empty types ty (zero-sized array, empty
 struct/union). __builtin_memcpy_aligned now supports the case sz = 0.

git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2392 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
---
 common/Memory.v | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 72 insertions(+), 6 deletions(-)

(limited to 'common/Memory.v')

diff --git a/common/Memory.v b/common/Memory.v
index 1115ed7..79fc8a0 100644
--- a/common/Memory.v
+++ b/common/Memory.v
@@ -29,6 +29,7 @@
 Require Import Zwf.
 Require Import Axioms.
 Require Import Coqlib.
+Require Intv.
 Require Import Maps.
 Require Import AST.
 Require Import Integers.
@@ -513,12 +514,21 @@ Proof.
   apply H. omega. apply IHn. intros. apply H. omega.
 Qed.
 
+Remark getN_setN_disjoint:
+  forall vl q c n p,
+  Intv.disjoint (p, p + Z_of_nat n) (q, q + Z_of_nat (length vl)) ->
+  getN n p (setN vl q c) = getN n p c.
+Proof.
+  intros. apply getN_exten. intros. apply setN_other.
+  intros; red; intros; subst r. eelim H; eauto. 
+Qed.
+
 Remark getN_setN_outside:
   forall vl q c n p,
   p + Z_of_nat n <= q \/ q + Z_of_nat (length vl) <= p ->
   getN n p (setN vl q c) = getN n p c.
 Proof.
-  intros. apply getN_exten. intros. apply setN_outside. omega. 
+  intros. apply getN_setN_disjoint. apply Intv.disjoint_range. auto. 
 Qed.
 
 Remark setN_default:
@@ -1559,12 +1569,10 @@ Proof.
   red; eauto with mem. 
 Qed.
 
-Theorem loadbytes_storebytes_other:
+Theorem loadbytes_storebytes_disjoint:
   forall b' ofs' len,
   len >= 0 ->
-  b' <> b
-  \/ ofs' + len <= ofs
-  \/ ofs + Z_of_nat (length bytes) <= ofs' ->
+  b' <> b \/ Intv.disjoint (ofs', ofs' + len) (ofs, ofs + Z_of_nat (length bytes)) ->
   loadbytes m2 b' ofs' len = loadbytes m1 b' ofs' len.
 Proof.
   intros. unfold loadbytes.
@@ -1572,13 +1580,25 @@ Proof.
   rewrite pred_dec_true. 
   rewrite storebytes_mem_contents. decEq. 
   rewrite PMap.gsspec. destruct (peq b' b). subst b'. 
-  apply getN_setN_outside. rewrite nat_of_Z_eq; auto. intuition congruence.
+  apply getN_setN_disjoint. rewrite nat_of_Z_eq; auto. intuition congruence.
   auto.
   red; auto with mem.
   apply pred_dec_false. 
   red; intros; elim n. red; auto with mem.
 Qed.
 
+Theorem loadbytes_storebytes_other:
+  forall b' ofs' len,
+  len >= 0 ->
+  b' <> b
+  \/ ofs' + len <= ofs
+  \/ ofs + Z_of_nat (length bytes) <= ofs' ->
+  loadbytes m2 b' ofs' len = loadbytes m1 b' ofs' len.
+Proof.
+  intros. apply loadbytes_storebytes_disjoint; auto. 
+  destruct H0; auto. right. apply Intv.disjoint_range; auto. 
+Qed.
+
 Theorem load_storebytes_other:
   forall chunk b' ofs',
   b' <> b
@@ -2599,6 +2619,31 @@ Proof.
   eauto with mem.
 Qed.
 
+Lemma storebytes_empty_inj:
+  forall f m1 b1 ofs1 m1' m2 b2 ofs2 m2',
+  mem_inj f m1 m2 ->
+  storebytes m1 b1 ofs1 nil = Some m1' ->
+  storebytes m2 b2 ofs2 nil = Some m2' ->
+  mem_inj f m1' m2'.
+Proof.
+  intros. destruct H. constructor. 
+(* perm *)
+  intros.
+  eapply perm_storebytes_1; eauto. 
+  eapply mi_perm0; eauto.
+  eapply perm_storebytes_2; eauto.
+(* align *)
+  intros. eapply mi_align0 with (ofs := ofs) (p := p); eauto.
+  red; intros. eapply perm_storebytes_2; eauto. 
+(* mem_contents *)
+  intros.
+  assert (perm m1 b0 ofs Cur Readable). eapply perm_storebytes_2; eauto. 
+  rewrite (storebytes_mem_contents _ _ _ _ _ H0).
+  rewrite (storebytes_mem_contents _ _ _ _ _ H1).
+  simpl. rewrite ! PMap.gsspec. 
+  destruct (peq b0 b1); destruct (peq b3 b2); subst; eapply mi_memval0; eauto.
+Qed.
+
 (** Preservation of allocations *)
 
 Lemma alloc_right_inj:
@@ -3583,6 +3628,27 @@ Proof.
   auto.
 Qed.
 
+Theorem storebytes_empty_inject:
+  forall f m1 b1 ofs1 m1' m2 b2 ofs2 m2',
+  inject f m1 m2 ->
+  storebytes m1 b1 ofs1 nil = Some m1' ->
+  storebytes m2 b2 ofs2 nil = Some m2' ->
+  inject f m1' m2'.
+Proof.
+  intros. inversion H. constructor; intros.
+(* inj *)
+  eapply storebytes_empty_inj; eauto.
+(* freeblocks *)
+  intros. apply mi_freeblocks0. red; intros; elim H2; eapply storebytes_valid_block_1; eauto.
+(* mappedblocks *)
+  intros. eapply storebytes_valid_block_1; eauto. 
+(* no overlap *)
+  red; intros. eapply mi_no_overlap0; eauto; eapply perm_storebytes_2; eauto. 
+(* representable *)
+  intros. eapply mi_representable0; eauto.
+  destruct H3; eauto using perm_storebytes_2. 
+Qed.
+
 (* Preservation of allocations *)
 
 Theorem alloc_right_inject:
-- 
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