Changeset 1875 for src/Clight/test

Timestamp:

Apr 4, 2012, 6:48:25 PM (9 years ago)

Author:

campbell

Message:

Update brief memory model test.

File:

• src/Clight/test/memorymodel.ma (modified) (2 diffs)

src/Clight/test/memorymodel.ma

@@ -20 +20 @@
    access, preventing you reading back more information than the memory can
    store. *)
-definition store0 := empty.
-definition store1block : mem × block ≝ alloc store0 0 4 Any.
+definition store0 := empty becontentT.
+definition store1block : mem × Σb:block.? ≝ alloc ? store0 0 4 Any.
 definition store1 : mem ≝ fst ?? store1block.
-definition block := snd ?? store1block.
+definition block :block := pi1 … (snd ?? store1block).
 
 (* write a value *)
 definition store2 : mem.
-  letin r ≝ (store Mint16unsigned store1 Any block 0 (Vint I16 (repr ? 1)));
+  letin r ≝ (store (ASTint I16 Unsigned) store1 (mk_pointer Any block (same_compat …) zero_offset) (Vint I16 (repr ? 1)));
 
   lapply (refl ? r); elim r in ⊢ (???% → ?); [ whd in ⊢ (??%? → ?); #H destruct
@@ -34 +34 @@
 (* overwrite the first byte of the value *)
 definition store3 : mem.
-  letin r ≝ (store Mint8unsigned store1 Any block 0 (Vint I8 (repr ? 1)));
+  letin r ≝ (store (ASTint I8 Unsigned) store2 (mk_pointer Any block (same_compat …) zero_offset) (Vint I8 (repr ? 1)));
 
   lapply (refl ? r) elim r in ⊢ (???% → ?); [ whd in ⊢ (??%? → ?); #H destruct
   | #rr #_ @ rr ] qed.
   
-(* The size checking rejects the read and gives us Some Vundef. *)
-example vl_undef: load Mint16signed store3 Any block 0 = Some ? Vundef. @refl qed.
+(* This is what happened under the original CompCert 1.6 ported memory model:
+   The size checking rejects the read and gives us Some Vundef.
+example vl_undef: load (ASTint I16 Signed) store3 (mk_pointer Any block (same_compat …) zero_offset) = Some ? Vundef. @refl qed.
+*)
+(* Now we do byte-wise values and get to see the altered integer. *)
+example vl_changed: load (ASTint I16 Signed) store3 (mk_pointer Any block (same_compat …) zero_offset) = Some ? (Vint I16 (repr ? 257)). @refl qed.
 
 (* The read is successful and returns the value. *)
-example vl_ok': load Mint8unsigned store3 Any block 0 = Some ? (Vint I8 (repr ? 1)). // qed.
+example vl_ok': load (ASTint I8 Unsigned) store3 (mk_pointer Any block (same_compat …) zero_offset) = Some ? (Vint I8 (repr ? 1)). // qed.
 
 (* NB: Double frees are allowed by the memory model (although not necessarily
        by the language). *)
-definition store4 := free store3 block.
-definition store5 : mem. letin r ≝ (free store3 block); whd in r; @r qed.
+definition store4 := free ? store3 block.
+definition store5 : mem. letin r ≝ (free ? store3 block); whd in r; @r qed.
 
 (* No ordering is imposed on deallocation (even though alloc and free are only used for
    stack memory in the semantics. *)
-definition storeA := empty.
-definition storeBblkB := alloc storeA 0 4 Any.
-definition storeCblkC := alloc (fst ?? storeBblkB) 0 8 Any.
-definition storeD := free (fst ?? storeCblkC) (snd ?? storeBblkB).
-definition storeE : mem. letin r ≝ (free storeD (snd ?? storeCblkC)).
+definition storeA := empty becontentT.
+definition storeBblkB := alloc ? storeA 0 4 Any.
+definition storeCblkC := alloc ? (fst ?? storeBblkB) 0 8 Any.
+definition storeD := free ? (fst ?? storeCblkC) (snd ?? storeBblkB).
+definition storeE : mem. letin r ≝ (free ? storeD (snd ?? storeCblkC)).
 whd in r; @r qed.
 
-(* Access to the "object representation" (as the C standard puts it) is not specified. *)
-definition storeI := empty.
-definition storeIIblk := alloc storeA 0 4 Any.
+(* Access to the "object representation" (as the C standard puts it) was not specified,
+   but can now split up integer values into bytes.  The front-end interface
+   doesn't currently expose parts of pointers. *)
+definition storeI := empty becontentT.
+definition storeIIblk := alloc ? storeA 0 4 Any.
 definition storeIII : mem.
- letin r ≝ (store Mint32 (fst ?? storeIIblk) Any (snd ?? storeIIblk) 0 (Vint I32 (repr ? 1)));
+ letin r ≝ (store (ASTint I32 Unsigned) (fst ?? storeIIblk) (mk_pointer Any (snd ?? storeIIblk) (same_compat …) zero_offset) (Vint I32 (repr ? 1)));
   lapply (refl ? r) elim r in ⊢ (???% → ?); [ whd in ⊢ (??%? → ?); #H destruct
   | #rr #_ @rr ] qed.
-definition byte := load Mint8unsigned storeIII Any (snd ?? storeIIblk) 0.
-example byteundef: byte = Some ? Vundef. // qed. (* :( *)
+definition byte := load (ASTint I8 Unsigned) storeIII (mk_pointer Any (snd ?? storeIIblk) (same_compat …) zero_offset).
+example byteundef: byte = Some ? (Vint I8 (repr ? 0)). // qed. (* :) *)