source: Deliverables/D3.1/C-semantics/Csem.ma @ 457

Last change on this file since 457 was 457, checked in by campbell, 8 years ago

Correct checking of function pointers.

File size: 78.7 KB
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1(* *********************************************************************)
2(*                                                                     *)
3(*              The Compcert verified compiler                         *)
4(*                                                                     *)
5(*          Xavier Leroy, INRIA Paris-Rocquencourt                     *)
6(*                                                                     *)
7(*  Copyright Institut National de Recherche en Informatique et en     *)
8(*  Automatique.  All rights reserved.  This file is distributed       *)
9(*  under the terms of the GNU General Public License as published by  *)
10(*  the Free Software Foundation, either version 2 of the License, or  *)
11(*  (at your option) any later version.  This file is also distributed *)
12(*  under the terms of the INRIA Non-Commercial License Agreement.     *)
13(*                                                                     *)
14(* *********************************************************************)
15
16(* * Dynamic semantics for the Clight language *)
17
18include "Coqlib.ma".
19include "Errors.ma".
20include "Integers.ma".
21include "Floats.ma".
22include "Values.ma".
23include "AST.ma".
24include "Mem.ma".
25include "Globalenvs.ma".
26include "Csyntax.ma".
27include "Maps.ma".
28include "Events.ma".
29include "Smallstep.ma".
30
31(* * * Semantics of type-dependent operations *)
32
33(* * Interpretation of values as truth values.
34  Non-zero integers, non-zero floats and non-null pointers are
35  considered as true.  The integer zero (which also represents
36  the null pointer) and the float 0.0 are false. *)
37
38ninductive is_false: val → type → Prop ≝
39  | is_false_int: ∀sz,sg.
40      is_false (Vint zero) (Tint sz sg)
41  | is_false_pointer: ∀s,t.
42      is_false (Vint zero) (Tpointer s t)
43 | is_false_float: ∀sz.
44      is_false (Vfloat Fzero) (Tfloat sz).
45
46ninductive is_true: val → type → Prop ≝
47  | is_true_int_int: ∀n,sz,sg.
48      n ≠ zero →
49      is_true (Vint n) (Tint sz sg)
50  | is_true_pointer_int: ∀psp,b,ofs,sz,sg.
51      is_true (Vptr psp b ofs) (Tint sz sg)
52  | is_true_int_pointer: ∀n,s,t.
53      n ≠ zero →
54      is_true (Vint n) (Tpointer s t)
55  | is_true_pointer_pointer: ∀psp,b,ofs,s,t.
56      is_true (Vptr psp b ofs) (Tpointer s t)
57  | is_true_float: ∀f,sz.
58      f ≠ Fzero →
59      is_true (Vfloat f) (Tfloat sz).
60
61ninductive bool_of_val : val → type → val → Prop ≝
62  | bool_of_val_true: ∀v,ty.
63         is_true v ty →
64         bool_of_val v ty Vtrue
65  | bool_of_val_false: ∀v,ty.
66        is_false v ty →
67        bool_of_val v ty Vfalse.
68
69(* * The following [sem_] functions compute the result of an operator
70  application.  Since operators are overloaded, the result depends
71  both on the static types of the arguments and on their run-time values.
72  Unlike in C, automatic conversions between integers and floats
73  are not performed.  For instance, [e1 + e2] is undefined if [e1]
74  is a float and [e2] an integer.  The Clight producer must have explicitly
75  promoted [e2] to a float. *)
76
77nlet rec sem_neg (v: val) (ty: type) : option val ≝
78  match ty with
79  [ Tint _ _ ⇒
80      match v with
81      [ Vint n ⇒ Some ? (Vint (neg n))
82      | _ => None ?
83      ]
84  | Tfloat _ ⇒
85      match v with
86      [ Vfloat f ⇒ Some ? (Vfloat (Fneg f))
87      | _ ⇒ None ?
88      ]
89  | _ ⇒ None ?
90  ].
91
92nlet rec sem_notint (v: val) : option val ≝
93  match v with
94  [ Vint n ⇒ Some ? (Vint (xor n mone))
95  | _ ⇒ None ?
96  ].
97
98nlet rec sem_notbool (v: val) (ty: type) : option val ≝
99  match ty with
100  [ Tint _ _ ⇒
101      match v with
102      [ Vint n ⇒ Some ? (of_bool (eq n zero))
103      | Vptr _ _ _ ⇒ Some ? Vfalse
104      | _ ⇒ None ?
105      ]
106  | Tpointer _ _ ⇒
107      match v with
108      [ Vint n ⇒ Some ? (of_bool (eq n zero))
109      | Vptr _ _ _ ⇒ Some ? Vfalse
110      | _ ⇒ None ?
111      ]
112  | Tfloat _ ⇒
113      match v with
114      [ Vfloat f ⇒ Some ? (of_bool (Fcmp Ceq f Fzero))
115      | _ ⇒ None ?
116      ]
117  | _ ⇒ None ?
118  ].
119
120nlet rec sem_add (v1:val) (t1:type) (v2: val) (t2:type) : option val ≝
121  match classify_add t1 t2 with
122  [ add_case_ii ⇒                       (**r integer addition *)
123      match v1 with
124      [ Vint n1 ⇒ match v2 with
125        [ Vint n2 ⇒ Some ? (Vint (add n1 n2))
126        | _ ⇒ None ? ]
127      | _ ⇒ None ? ]
128  | add_case_ff ⇒                       (**r float addition *)
129      match v1 with
130      [ Vfloat n1 ⇒ match v2 with
131        [ Vfloat n2 ⇒ Some ? (Vfloat (Fadd n1 n2))
132        | _ ⇒ None ? ]
133      | _ ⇒ None ? ]
134  | add_case_pi ty ⇒                    (**r pointer plus integer *)
135      match v1 with
136      [ Vptr pcl1 b1 ofs1 ⇒ match v2 with
137        [ Vint n2 ⇒ Some ? (Vptr pcl1 b1 (add ofs1 (mul (repr (sizeof ty)) n2)))
138        | _ ⇒ None ? ]
139      | _ ⇒ None ? ]
140  | add_case_ip ty ⇒                    (**r integer plus pointer *)
141      match v1 with
142      [ Vint n1 ⇒ match v2 with
143        [ Vptr pcl2 b2 ofs2 ⇒ Some ? (Vptr pcl2 b2 (add ofs2 (mul (repr (sizeof ty)) n1)))
144        | _ ⇒ None ? ]
145      | _ ⇒ None ? ]
146  | add_default ⇒ None ?
147].
148
149nlet rec sem_sub (v1:val) (t1:type) (v2: val) (t2:type) : option val ≝
150  match classify_sub t1 t2 with
151  [ sub_case_ii ⇒                (**r integer subtraction *)
152      match v1 with
153      [ Vint n1 ⇒ match v2 with
154        [ Vint n2 ⇒ Some ? (Vint (sub n1 n2))
155        | _ ⇒ None ? ]
156      | _ ⇒ None ? ]
157  | sub_case_ff ⇒                (**r float subtraction *)
158      match v1 with
159      [ Vfloat f1 ⇒ match v2 with
160        [ Vfloat f2 ⇒ Some ? (Vfloat (Fsub f1 f2))
161        | _ ⇒ None ? ]
162      | _ ⇒ None ? ]
163  | sub_case_pi ty ⇒             (**r pointer minus integer *)
164      match v1 with
165      [ Vptr pcl1 b1 ofs1 ⇒ match v2 with
166        [ Vint n2 ⇒ Some ? (Vptr pcl1 b1 (sub ofs1 (mul (repr (sizeof ty)) n2)))
167        | _ ⇒ None ? ]
168      | _ ⇒ None ? ]
169  | sub_case_pp ty ⇒             (**r pointer minus pointer *)
170      match v1 with
171      [ Vptr pcl1 b1 ofs1 ⇒ match v2 with
172        [ Vptr pcl2 b2 ofs2 ⇒
173          if eqZb b1 b2 then
174            if eq (repr (sizeof ty)) zero then None ?
175            else Some ? (Vint (divu (sub ofs1 ofs2) (repr (sizeof ty))))
176          else None ?
177        | _ ⇒ None ? ]
178      | _ ⇒ None ? ]
179  | sub_default ⇒ None ?
180  ].
181
182nlet rec sem_mul (v1:val) (t1:type) (v2: val) (t2:type) : option val ≝
183 match classify_mul t1 t2 with
184  [ mul_case_ii ⇒
185      match v1 with
186      [ Vint n1 ⇒ match v2 with
187        [ Vint n2 ⇒ Some ? (Vint (mul n1 n2))
188        | _ ⇒ None ? ]
189      | _ ⇒ None ? ]
190  | mul_case_ff ⇒
191      match v1 with
192      [ Vfloat f1 ⇒ match v2 with
193        [ Vfloat f2 ⇒ Some ? (Vfloat (Fmul f1 f2))
194        | _ ⇒ None ? ]
195      | _ ⇒ None ? ]
196  | mul_default ⇒
197      None ?
198].
199
200nlet rec sem_div (v1:val) (t1:type) (v2: val) (t2:type) : option val ≝
201  match classify_div t1 t2 with
202  [ div_case_I32unsi ⇒
203      match v1 with
204      [ Vint n1 ⇒ match v2 with
205        [ Vint n2 ⇒ if eq n2 zero then None ? else Some ? (Vint (divu n1 n2))
206        | _ ⇒ None ? ]
207      | _ ⇒ None ? ]
208  | div_case_ii ⇒
209      match v1 with
210       [ Vint n1 ⇒ match v2 with
211         [ Vint n2 ⇒ if eq n2 zero then None ? else Some ? (Vint(divs n1 n2))
212         | _ ⇒ None ? ]
213      | _ ⇒ None ? ]
214  | div_case_ff ⇒
215      match v1 with
216      [ Vfloat f1 ⇒ match v2 with
217        [ Vfloat f2 ⇒ Some ? (Vfloat(Fdiv f1 f2))
218        | _ ⇒ None ? ]
219      | _ ⇒ None ? ]
220  | div_default ⇒
221      None ?
222  ].
223
224nlet rec sem_mod (v1:val) (t1:type) (v2: val) (t2:type) : option val ≝
225  match classify_mod t1 t2 with
226  [ mod_case_I32unsi ⇒
227      match v1 with
228      [ Vint n1 ⇒ match v2 with
229        [ Vint n2 ⇒ if eq n2 zero then None ? else Some ? (Vint (modu n1 n2))
230        | _ ⇒ None ? ]
231      | _ ⇒ None ? ]
232  | mod_case_ii ⇒
233      match v1 with
234      [ Vint n1 ⇒ match v2 with
235        [ Vint n2 ⇒ if eq n2 zero then None ? else Some ? (Vint (mods n1 n2))
236        | _ ⇒ None ? ]
237      | _ ⇒ None ? ]
238  | mod_default ⇒
239      None ?
240  ].
241
242nlet rec sem_and (v1,v2: val) : option val ≝
243  match v1 with
244  [ Vint n1 ⇒ match v2 with
245    [ Vint n2 ⇒ Some ? (Vint(i_and n1 n2))
246    | _ ⇒ None ? ]
247  | _ ⇒ None ?
248  ].
249
250nlet rec sem_or (v1,v2: val) : option val ≝
251  match v1 with
252  [ Vint n1 ⇒ match v2 with
253    [ Vint n2 ⇒ Some ? (Vint(or n1 n2))
254    | _ ⇒ None ? ]
255  | _ ⇒ None ?
256  ].
257
258nlet rec sem_xor (v1,v2: val) : option val ≝
259  match v1 with
260  [ Vint n1 ⇒ match v2 with
261    [ Vint n2 ⇒ Some ? (Vint(xor n1 n2))
262    | _ ⇒ None ? ]
263  | _ ⇒ None ?
264  ].
265
266nlet rec sem_shl (v1,v2: val): option val ≝
267  match v1 with
268  [ Vint n1 ⇒ match v2 with
269    [ Vint n2 ⇒
270        if ltu n2 iwordsize then Some ? (Vint(shl n1 n2)) else None ?
271    | _ ⇒ None ? ]
272  | _ ⇒ None ? ].
273
274nlet rec sem_shr (v1: val) (t1: type) (v2: val) (t2: type): option val ≝
275  match classify_shr t1 t2 with
276  [ shr_case_I32unsi ⇒
277      match v1 with
278      [ Vint n1 ⇒ match v2 with
279        [ Vint n2 ⇒
280            if ltu n2 iwordsize then Some ? (Vint (shru n1 n2)) else None ?
281        | _ ⇒ None ? ]
282      | _ ⇒ None ? ]
283   | shr_case_ii =>
284      match v1 with
285      [ Vint n1 ⇒ match v2 with
286        [ Vint n2 ⇒
287            if ltu n2 iwordsize then Some ? (Vint (shr n1 n2)) else None ?
288        | _ ⇒ None ? ]
289      | _ ⇒ None ? ]
290   | shr_default ⇒
291      None ?
292   ].
293
294nlet rec sem_cmp_mismatch (c: comparison): option val ≝
295  match c with
296  [ Ceq =>  Some ? Vfalse
297  | Cne =>  Some ? Vtrue
298  | _   => None ?
299  ].
300
301nlet rec sem_cmp (c:comparison)
302                  (v1: val) (t1: type) (v2: val) (t2: type)
303                  (m: mem): option val ≝
304  match classify_cmp t1 t2 with
305  [ cmp_case_I32unsi ⇒
306      match v1 with
307      [ Vint n1 ⇒ match v2 with
308        [ Vint n2 ⇒ Some ? (of_bool (cmpu c n1 n2))
309        | _ ⇒ None ? ]
310      | _ ⇒ None ? ]
311  | cmp_case_ipip ⇒
312      match v1 with
313      [ Vint n1 ⇒ match v2 with
314         [ Vint n2 ⇒ Some ? (of_bool (cmp c n1 n2))
315         | Vptr psp b ofs ⇒ if eq n1 zero then sem_cmp_mismatch c else None ?
316         | _ ⇒ None ?
317         ]
318      | Vptr pcl1 b1 ofs1 ⇒
319        match v2 with
320        [ Vptr pcl2 b2 ofs2 ⇒
321          if valid_pointer m pcl1 b1 (signed ofs1)
322          ∧ valid_pointer m pcl2 b2 (signed ofs2) then
323            if eqZb b1 b2
324            then Some ? (of_bool (cmp c ofs1 ofs2))
325            else sem_cmp_mismatch c
326          else None ?
327        | Vint n ⇒
328          if eq n zero then sem_cmp_mismatch c else None ?
329        | _ ⇒ None ? ]
330      | _ ⇒ None ? ]
331  | cmp_case_ff ⇒
332      match v1 with
333      [ Vfloat f1 ⇒
334        match v2 with
335        [ Vfloat f2 ⇒ Some ? (of_bool (Fcmp c f1 f2))
336        | _ ⇒ None ? ]
337      | _ ⇒ None ? ]
338  | cmp_default ⇒ None ?
339  ].
340
341ndefinition sem_unary_operation
342            : unary_operation → val → type → option val ≝
343  λop,v,ty.
344  match op with
345  [ Onotbool => sem_notbool v ty
346  | Onotint => sem_notint v
347  | Oneg => sem_neg v ty
348  ].
349
350nlet rec sem_binary_operation
351    (op: binary_operation)
352    (v1: val) (t1: type) (v2: val) (t2:type)
353    (m: mem): option val ≝
354  match op with
355  [ Oadd ⇒ sem_add v1 t1 v2 t2
356  | Osub ⇒ sem_sub v1 t1 v2 t2
357  | Omul ⇒ sem_mul v1 t1 v2 t2
358  | Omod ⇒ sem_mod v1 t1 v2 t2
359  | Odiv ⇒ sem_div v1 t1 v2 t2
360  | Oand ⇒ sem_and v1 v2 
361  | Oor  ⇒ sem_or v1 v2
362  | Oxor ⇒ sem_xor v1 v2
363  | Oshl ⇒ sem_shl v1 v2
364  | Oshr ⇒ sem_shr v1 t1 v2 t2
365  | Oeq ⇒ sem_cmp Ceq v1 t1 v2 t2 m
366  | One ⇒ sem_cmp Cne v1 t1 v2 t2 m
367  | Olt ⇒ sem_cmp Clt v1 t1 v2 t2 m
368  | Ogt ⇒ sem_cmp Cgt v1 t1 v2 t2 m
369  | Ole ⇒ sem_cmp Cle v1 t1 v2 t2 m
370  | Oge ⇒ sem_cmp Cge v1 t1 v2 t2 m
371  ].
372
373(* * Semantic of casts.  [cast v1 t1 t2 v2] holds if value [v1],
374  viewed with static type [t1], can be cast to type [t2],
375  resulting in value [v2].  *)
376
377nlet rec cast_int_int (sz: intsize) (sg: signedness) (i: int) : int ≝
378  match sz with
379  [ I8 ⇒ match sg with [ Signed ⇒ sign_ext 8 i | Unsigned ⇒ zero_ext 8 i ]
380  | I16 ⇒ match sg with [ Signed => sign_ext 16 i | Unsigned ⇒ zero_ext 16 i ]
381  | I32 ⇒ i
382  ].
383
384nlet rec cast_int_float (si : signedness) (i: int) : float ≝
385  match si with
386  [ Signed ⇒ floatofint i
387  | Unsigned ⇒ floatofintu i
388  ].
389
390nlet rec cast_float_int (si : signedness) (f: float) : int ≝
391  match si with
392  [ Signed ⇒ intoffloat f
393  | Unsigned ⇒ intuoffloat f
394  ].
395
396nlet rec cast_float_float (sz: floatsize) (f: float) : float ≝
397  match sz with
398  [ F32 ⇒ singleoffloat f
399  | F64 ⇒ f
400  ].
401
402ninductive type_pointable : type → Prop ≝
403          (* All integer sizes can represent at least one kind of pointer *)
404| type_ptr_pointer : ∀s,t. type_pointable (Tpointer s t)
405| type_ptr_array : ∀s,t,n. type_pointable (Tarray s t n)
406| type_ptr_function : ∀tys,ty. type_pointable (Tfunction tys ty).
407
408ninductive type_space : type → memory_space → Prop ≝
409| type_spc_pointer : ∀s,t. type_space (Tpointer s t) s
410| type_spc_array : ∀s,t,n. type_space (Tarray s t n) s
411(* XXX Is the following necessary? *)
412| type_spc_code : ∀tys,ty. type_space (Tfunction tys ty) Code.
413
414ninductive cast : mem → val → type → type → val → Prop ≝
415  | cast_ii:   ∀m,i,sz2,sz1,si1,si2.            (**r int to int  *)
416      cast m (Vint i) (Tint sz1 si1) (Tint sz2 si2)
417           (Vint (cast_int_int sz2 si2 i))
418  | cast_fi:   ∀m,f,sz1,sz2,si2.                (**r float to int *)
419      cast m (Vfloat f) (Tfloat sz1) (Tint sz2 si2)
420           (Vint (cast_int_int sz2 si2 (cast_float_int si2 f)))
421  | cast_if:   ∀m,i,sz1,sz2,si1.                (**r int to float  *)
422      cast m (Vint i) (Tint sz1 si1) (Tfloat sz2)
423          (Vfloat (cast_float_float sz2 (cast_int_float si1 i)))
424  | cast_ff:   ∀m,f,sz1,sz2.                    (**r float to float *)
425      cast m (Vfloat f) (Tfloat sz1) (Tfloat sz2)
426           (Vfloat (cast_float_float sz2 f))
427  | cast_pp: ∀m,psp,psp',ty,ty',b,ofs.
428      type_space ty psp →
429      type_space ty' psp' →
430      pointer_compat (block_space m b) psp' →
431      cast m (Vptr psp b ofs) ty ty' (Vptr psp' b ofs)
432  | cast_ip_z: ∀m,sz,sg,ty'.
433      type_pointable ty' →
434      cast m (Vint zero) (Tint sz sg) ty' (Vint zero)
435  | cast_pp_z: ∀m,ty,ty'.
436      type_pointable ty →
437      type_pointable ty' →
438      cast m (Vint zero) ty ty' (Vint zero).
439(* Should probably also allow pointers to pass through sufficiently large
440   unsigned integers. *)
441(* Perhaps a little too generous?  For example, some integers may not
442   represent a valid generic pointer.
443  | cast_pp_i: ∀m,n,ty,ty',t1,t2.     (**r no change in data representation *)
444      type_pointable ty →
445      type_pointable ty' →
446      sizeof ty ≤ sizeof ty' →
447      cast m (Vint n) t1 t2 (Vint n).
448*)
449
450(* * * Operational semantics *)
451
452(* * The semantics uses two environments.  The global environment
453  maps names of functions and global variables to memory block references,
454  and function pointers to their definitions.  (See module [Globalenvs].) *)
455
456ndefinition genv ≝ (genv_t Genv) fundef.
457
458(* * The local environment maps local variables to block references.
459  The current value of the variable is stored in the associated memory
460  block. *)
461
462ndefinition env ≝ (tree_t ? PTree) block. (* map variable -> location *)
463
464ndefinition empty_env: env ≝ (empty …).
465
466(* * [load_value_of_type ty m b ofs] computes the value of a datum
467  of type [ty] residing in memory [m] at block [b], offset [ofs].
468  If the type [ty] indicates an access by value, the corresponding
469  memory load is performed.  If the type [ty] indicates an access by
470  reference, the pointer [Vptr b ofs] is returned. *)
471
472nlet rec load_value_of_type (ty: type) (m: mem) (psp:memory_space) (b: block) (ofs: int) : option val ≝
473  match access_mode ty with
474  [ By_value chunk ⇒ loadv chunk m (Vptr psp b ofs)
475  | By_reference ⇒ Some ? (Vptr psp b ofs)
476  | By_nothing ⇒ None ?
477  ].
478
479(* * Symmetrically, [store_value_of_type ty m b ofs v] returns the
480  memory state after storing the value [v] in the datum
481  of type [ty] residing in memory [m] at block [b], offset [ofs].
482  This is allowed only if [ty] indicates an access by value. *)
483
484nlet rec store_value_of_type (ty_dest: type) (m: mem) (psp:memory_space) (loc: block) (ofs: int) (v: val) : option mem ≝
485  match access_mode ty_dest with
486  [ By_value chunk ⇒ storev chunk m (Vptr psp loc ofs) v
487  | By_reference ⇒ None ?
488  | By_nothing ⇒ None ?
489  ].
490
491(* * Allocation of function-local variables.
492  [alloc_variables e1 m1 vars e2 m2] allocates one memory block
493  for each variable declared in [vars], and associates the variable
494  name with this block.  [e1] and [m1] are the initial local environment
495  and memory state.  [e2] and [m2] are the final local environment
496  and memory state. *)
497
498ninductive alloc_variables: env → mem →
499                            list (ident × type) →
500                            env → mem → Prop ≝
501  | alloc_variables_nil:
502      ∀e,m.
503      alloc_variables e m (nil ?) e m
504  | alloc_variables_cons:
505      ∀e,m,id,ty,vars,m1,b1,m2,e2.
506      alloc m 0 (sizeof ty) Any = 〈m1, b1〉 →
507      alloc_variables (set … id b1 e) m1 vars e2 m2 →
508      alloc_variables e m (〈id, ty〉 :: vars) e2 m2.
509
510(* * Initialization of local variables that are parameters to a function.
511  [bind_parameters e m1 params args m2] stores the values [args]
512  in the memory blocks corresponding to the variables [params].
513  [m1] is the initial memory state and [m2] the final memory state. *)
514
515ninductive bind_parameters: env →
516                           mem → list (ident × type) → list val →
517                           mem → Prop ≝
518  | bind_parameters_nil:
519      ∀e,m.
520      bind_parameters e m (nil ?) (nil ?) m
521  | bind_parameters_cons:
522      ∀e,m,id,ty,params,v1,vl,b,m1,m2.
523      get ??? id e = Some ? b →
524      store_value_of_type ty m Any b zero v1 = Some ? m1 →
525      bind_parameters e m1 params vl m2 →
526      bind_parameters e m (〈id, ty〉 :: params) (v1 :: vl) m2.
527
528(* XXX: this doesn't look right - we're assigning arbitrary memory spaces to
529   parameters? *)
530
531(* * Return the list of blocks in the codomain of [e]. *)
532
533ndefinition blocks_of_env : env → list block ≝ λe.
534  map ?? (λx. snd ?? x) (elements ??? e).
535
536(* * Selection of the appropriate case of a [switch], given the value [n]
537  of the selector expression. *)
538
539nlet rec select_switch (n: int) (sl: labeled_statements)
540                       on sl : labeled_statements ≝
541  match sl with
542  [ LSdefault _ ⇒ sl
543  | LScase c s sl' ⇒ if eq c n then sl else select_switch n sl'
544  ].
545
546(* * Turn a labeled statement into a sequence *)
547
548nlet rec seq_of_labeled_statement (sl: labeled_statements) : statement ≝
549  match sl with
550  [ LSdefault s ⇒ s
551  | LScase c s sl' ⇒ Ssequence s (seq_of_labeled_statement sl')
552  ].
553
554(*
555Section SEMANTICS.
556
557Variable ge: genv.
558
559(** ** Evaluation of expressions *)
560
561Section EXPR.
562
563Variable e: env.
564Variable m: mem.
565*)
566(* * [eval_expr ge e m a v] defines the evaluation of expression [a]
567  in r-value position.  [v] is the value of the expression.
568  [e] is the current environment and [m] is the current memory state. *)
569
570ninductive eval_expr (ge:genv) (e:env) (m:mem) : expr → val → trace → Prop ≝
571  | eval_Econst_int:   ∀i,ty.
572      eval_expr ge e m (Expr (Econst_int i) ty) (Vint i) E0
573  | eval_Econst_float:   ∀f,ty.
574      eval_expr ge e m (Expr (Econst_float f) ty) (Vfloat f) E0
575  | eval_Elvalue: ∀a,ty,psp,loc,ofs,v,tr.
576      eval_lvalue ge e m (Expr a ty) psp loc ofs tr →
577      load_value_of_type ty m psp loc ofs = Some ? v →
578      eval_expr ge e m (Expr a ty) v tr
579  | eval_Eaddrof: ∀a,ty,psp,loc,ofs,tr.
580      eval_lvalue ge e m a psp loc ofs tr →
581      eval_expr ge e m (Expr (Eaddrof a) ty) (Vptr psp loc ofs) tr
582  | eval_Esizeof: ∀ty',ty.
583      eval_expr ge e m (Expr (Esizeof ty') ty) (Vint (repr (sizeof ty'))) E0
584  | eval_Eunop:  ∀op,a,ty,v1,v,tr.
585      eval_expr ge e m a v1 tr →
586      sem_unary_operation op v1 (typeof a) = Some ? v →
587      eval_expr ge e m (Expr (Eunop op a) ty) v tr
588  | eval_Ebinop: ∀op,a1,a2,ty,v1,v2,v,tr1,tr2.
589      eval_expr ge e m a1 v1 tr1 →
590      eval_expr ge e m a2 v2 tr2 →
591      sem_binary_operation op v1 (typeof a1) v2 (typeof a2) m = Some ? v →
592      eval_expr ge e m (Expr (Ebinop op a1 a2) ty) v (tr1⧺tr2)
593  | eval_Econdition_true: ∀a1,a2,a3,ty,v1,v2,tr1,tr2.
594      eval_expr ge e m a1 v1 tr1 →
595      is_true v1 (typeof a1) →
596      eval_expr ge e m a2 v2 tr2 →
597      eval_expr ge e m (Expr (Econdition a1 a2 a3) ty) v2 (tr1⧺tr2)
598  | eval_Econdition_false: ∀a1,a2,a3,ty,v1,v3,tr1,tr2.
599      eval_expr ge e m a1 v1 tr1 →
600      is_false v1 (typeof a1) →
601      eval_expr ge e m a3 v3 tr2 →
602      eval_expr ge e m (Expr (Econdition a1 a2 a3) ty) v3 (tr1⧺tr2)
603  | eval_Eorbool_1: ∀a1,a2,ty,v1,tr.
604      eval_expr ge e m a1 v1 tr →
605      is_true v1 (typeof a1) →
606      eval_expr ge e m (Expr (Eorbool a1 a2) ty) Vtrue tr
607  | eval_Eorbool_2: ∀a1,a2,ty,v1,v2,v,tr1,tr2.
608      eval_expr ge e m a1 v1 tr1 →
609      is_false v1 (typeof a1) →
610      eval_expr ge e m a2 v2 tr2 →
611      bool_of_val v2 (typeof a2) v →
612      eval_expr ge e m (Expr (Eorbool a1 a2) ty) v (tr1⧺tr2)
613  | eval_Eandbool_1: ∀a1,a2,ty,v1,tr.
614      eval_expr ge e m a1 v1 tr →
615      is_false v1 (typeof a1) →
616      eval_expr ge e m (Expr (Eandbool a1 a2) ty) Vfalse tr
617  | eval_Eandbool_2: ∀a1,a2,ty,v1,v2,v,tr1,tr2.
618      eval_expr ge e m a1 v1 tr1 →
619      is_true v1 (typeof a1) →
620      eval_expr ge e m a2 v2 tr2 →
621      bool_of_val v2 (typeof a2) v →
622      eval_expr ge e m (Expr (Eandbool a1 a2) ty) v (tr1⧺tr2)
623  | eval_Ecast:   ∀a,ty,ty',v1,v,tr.
624      eval_expr ge e m a v1 tr →
625      cast m v1 (typeof a) ty v →
626      eval_expr ge e m (Expr (Ecast ty a) ty') v tr
627  | eval_Ecost: ∀a,ty,v,l,tr.
628      eval_expr ge e m a v tr →
629      eval_expr ge e m (Expr (Ecost l a) ty) v (tr⧺Echarge l)
630
631(* * [eval_lvalue ge e m a b ofs] defines the evaluation of expression [a]
632  in l-value position.  The result is the memory location [b, ofs]
633  that contains the value of the expression [a]. *)
634
635with eval_lvalue (*(ge:genv) (e:env) (m:mem)*) : expr → memory_space → block → int → trace → Prop ≝
636  | eval_Evar_local:   ∀id,l,ty.
637      (* XXX notation? e!id*) get ??? id e = Some ? l →
638      eval_lvalue ge e m (Expr (Evar id) ty) Any l zero E0
639  | eval_Evar_global: ∀id,sp,l,ty.
640      (* XXX e!id *) get ??? id e = None ? →
641      find_symbol ?? ge id = Some ? 〈sp,l〉 →
642      eval_lvalue ge e m (Expr (Evar id) ty) sp l zero E0
643  | eval_Ederef: ∀a,ty,psp,l,ofs,tr.
644      eval_expr ge e m a (Vptr psp l ofs) tr →
645      eval_lvalue ge e m (Expr (Ederef a) ty) psp l ofs tr
646 | eval_Efield_struct:   ∀a,i,ty,psp,l,ofs,id,fList,delta,tr.
647      eval_lvalue ge e m a psp l ofs tr →
648      typeof a = Tstruct id fList →
649      field_offset i fList = OK ? delta →
650      eval_lvalue ge e m (Expr (Efield a i) ty) psp l (add ofs (repr delta)) tr
651 | eval_Efield_union:   ∀a,i,ty,psp,l,ofs,id,fList,tr.
652      eval_lvalue ge e m a psp l ofs tr →
653      typeof a = Tunion id fList →
654      eval_lvalue ge e m (Expr (Efield a i) ty) psp l ofs tr.
655
656nlet rec eval_expr_ind (ge:genv) (e:env) (m:mem)
657  (P:∀a,v,tr. eval_expr ge e m a v tr → Prop)
658  (eci:∀i,ty. P ??? (eval_Econst_int ge e m i ty))
659  (ecF:∀f,ty. P ??? (eval_Econst_float ge e m f ty))
660  (elv:∀a,ty,psp,loc,ofs,v,tr,H1,H2. P ??? (eval_Elvalue ge e m a ty psp loc ofs v tr H1 H2))
661  (ead:∀a,ty,psp,loc,ofs,tr,H. P ??? (eval_Eaddrof ge e m a ty psp loc ofs tr H))
662  (esz:∀ty',ty. P ??? (eval_Esizeof ge e m ty' ty))
663  (eun:∀op,a,ty,v1,v,tr,H1,H2. P a v1 tr H1 → P ??? (eval_Eunop ge e m op a ty v1 v tr H1 H2))
664  (ebi:∀op,a1,a2,ty,v1,v2,v,tr1,tr2,H1,H2,H3. P a1 v1 tr1 H1 → P a2 v2 tr2 H2 → P ??? (eval_Ebinop ge e m op a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3))
665  (ect:∀a1,a2,a3,ty,v1,v2,tr1,tr2,H1,H2,H3. P a1 v1 tr1 H1 → P a2 v2 tr2 H3 → P ??? (eval_Econdition_true ge e m a1 a2 a3 ty v1 v2 tr1 tr2 H1 H2 H3))
666  (ecf:∀a1,a2,a3,ty,v1,v3,tr1,tr2,H1,H2,H3. P a1 v1 tr1 H1 → P a3 v3 tr2 H3 → P ??? (eval_Econdition_false ge e m a1 a2 a3 ty v1 v3 tr1 tr2 H1 H2 H3))
667  (eo1:∀a1,a2,ty,v1,tr,H1,H2. P a1 v1 tr H1 → P ??? (eval_Eorbool_1 ge e m a1 a2 ty v1 tr H1 H2))
668  (eo2:∀a1,a2,ty,v1,v2,v,tr1,tr2,H1,H2,H3,H4. P a1 v1 tr1 H1 → P a2 v2 tr2 H3 → P ??? (eval_Eorbool_2 ge e m a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4))
669  (ea1:∀a1,a2,ty,v1,tr,H1,H2. P a1 v1 tr H1 → P ??? (eval_Eandbool_1 ge e m a1 a2 ty v1 tr H1 H2))
670  (ea2:∀a1,a2,ty,v1,v2,v,tr1,tr2,H1,H2,H3,H4. P a1 v1 tr1 H1 → P a2 v2 tr2 H3 → P ??? (eval_Eandbool_2 ge e m a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4))
671  (ecs:∀a,ty,ty',v1,v,tr,H1,H2. P a v1 tr H1 → P ??? (eval_Ecast ge e m a ty ty' v1 v tr H1 H2))
672  (eco:∀a,ty,v,l,tr,H. P a v tr H → P ??? (eval_Ecost ge e m a ty v l tr H))
673  (a:expr) (v:val) (tr:trace) (ev:eval_expr ge e m a v tr) on ev : P a v tr ev ≝
674  match ev with
675  [ eval_Econst_int i ty ⇒ eci i ty
676  | eval_Econst_float f ty ⇒ ecF f ty
677  | eval_Elvalue a ty psp loc ofs v tr H1 H2 ⇒ elv a ty psp loc ofs v tr H1 H2
678  | eval_Eaddrof a ty psp loc ofs tr H ⇒ ead a ty psp loc ofs tr H
679  | eval_Esizeof ty' ty ⇒ esz ty' ty
680  | eval_Eunop op a ty v1 v tr H1 H2 ⇒ eun op a ty v1 v tr H1 H2 (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a v1 tr H1)
681  | eval_Ebinop op a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 ⇒ ebi op a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a1 v1 tr1 H1) (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a2 v2 tr2 H2)
682  | eval_Econdition_true a1 a2 a3 ty v1 v2 tr1 tr2 H1 H2 H3 ⇒ ect a1 a2 a3 ty v1 v2 tr1 tr2 H1 H2 H3 (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a1 v1 tr1 H1) (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a2 v2 tr2 H3)
683  | eval_Econdition_false a1 a2 a3 ty v1 v3 tr1 tr2 H1 H2 H3 ⇒ ecf a1 a2 a3 ty v1 v3 tr1 tr2 H1 H2 H3 (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a1 v1 tr1 H1) (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a3 v3 tr2 H3)
684  | eval_Eorbool_1 a1 a2 ty v1 tr H1 H2 ⇒ eo1 a1 a2 ty v1 tr H1 H2 (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a1 v1 tr H1)
685  | eval_Eorbool_2 a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4 ⇒ eo2 a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4 (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a1 v1 tr1 H1) (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a2 v2 tr2 H3)
686  | eval_Eandbool_1 a1 a2 ty v1 tr H1 H2 ⇒ ea1 a1 a2 ty v1 tr H1 H2 (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a1 v1 tr H1)
687  | eval_Eandbool_2 a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4 ⇒ ea2 a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4 (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a1 v1 tr1 H1) (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a2 v2 tr2 H3)
688  | eval_Ecast a ty ty' v1 v tr H1 H2 ⇒ ecs a ty ty' v1 v tr H1 H2 (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a v1 tr H1)
689  | eval_Ecost a ty v l tr H ⇒ eco a ty v l tr H (eval_expr_ind ge e m P eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco a v tr H)
690  ].
691
692ninverter eval_expr_inv_ind for eval_expr : Prop.
693
694nlet rec eval_lvalue_ind (ge:genv) (e:env) (m:mem)
695  (P:∀a,psp,loc,ofs,tr. eval_lvalue ge e m a psp loc ofs tr → Prop)
696  (lvl:∀id,l,ty,H. P ????? (eval_Evar_local ge e m id l ty H))
697  (lvg:∀id,sp,l,ty,H1,H2. P ????? (eval_Evar_global ge e m id sp l ty H1 H2))
698  (lde:∀a,ty,psp,l,ofs,tr,H. P ????? (eval_Ederef ge e m a ty psp l ofs tr H))
699  (lfs:∀a,i,ty,psp,l,ofs,id,fList,delta,tr,H1,H2,H3. P a psp l ofs tr H1 → P ????? (eval_Efield_struct ge e m a i ty psp l ofs id fList delta tr H1 H2 H3))
700  (lfu:∀a,i,ty,psp,l,ofs,id,fList,tr,H1,H2. P a psp l ofs tr H1 → P ????? (eval_Efield_union ge e m a i ty psp l ofs id fList tr H1 H2))
701  (a:expr) (psp:memory_space) (loc:block) (ofs:int) (tr:trace) (ev:eval_lvalue ge e m a psp loc ofs tr) on ev : P a psp loc ofs tr ev ≝
702  match ev with
703  [ eval_Evar_local id l ty H ⇒ lvl id l ty H
704  | eval_Evar_global id sp l ty H1 H2 ⇒ lvg id sp l ty H1 H2
705  | eval_Ederef a ty psp l ofs tr H ⇒ lde a ty psp l ofs tr H
706  | eval_Efield_struct a i ty psp l ofs id fList delta tr H1 H2 H3 ⇒ lfs a i ty psp l ofs id fList delta tr H1 H2 H3 (eval_lvalue_ind ge e m P lvl lvg lde lfs lfu a psp l ofs tr H1)
707  | eval_Efield_union a i ty psp l ofs id fList tr H1 H2 ⇒ lfu a i ty psp l ofs id fList tr H1 H2 (eval_lvalue_ind ge e m P lvl lvg lde lfs lfu a psp l ofs tr H1)
708  ].
709
710(*
711ninverter eval_lvalue_inv_ind for eval_lvalue : Prop.
712*)
713
714ndefinition eval_lvalue_inv_ind :
715  ∀x1: genv.
716   ∀x2: env.
717    ∀x3: mem.
718     ∀x4: expr.
719      ∀x5: memory_space.
720       ∀x6: block.
721        ∀x7: int.
722         ∀x8: trace.
723          ∀P:
724            ∀_z1430: expr.
725             ∀_z1429: memory_space.
726              ∀_z1428: block. ∀_z1427: int. ∀_z1426: trace. Prop.
727           ∀_H1: ?.
728            ∀_H2: ?.
729             ∀_H3: ?.
730              ∀_H4: ?.
731               ∀_H5: ?.
732                ∀_Hterm: eval_lvalue x1 x2 x3 x4 x5 x6 x7 x8.
733                 P x4 x5 x6 x7 x8
734:=
735  (λx1:genv.
736    (λx2:env.
737      (λx3:mem.
738        (λx4:expr.
739          (λx5:memory_space.
740            (λx6:block.
741              (λx7:int.
742                (λx8:trace.
743                  (λP:∀_z1430: expr.
744                        ∀_z1429: memory_space.
745                         ∀_z1428: block.
746                          ∀_z1427: int. ∀_z1426: trace. Prop.
747                    (λH1:?.
748                      (λH2:?.
749                        (λH3:?.
750                          (λH4:?.
751                            (λH5:?.
752                              (λHterm:eval_lvalue x1 x2 x3 x4 x5 x6 x7 x8.
753                                ((λHcut:∀z1435: eq expr x4 x4.
754                                          ∀z1434: eq memory_space x5 x5.
755                                           ∀z1433: eq block x6 x6.
756                                            ∀z1432: eq int x7 x7.
757                                             ∀z1431: eq trace x8 x8.
758                                              P x4 x5 x6 x7 x8.
759                                   (Hcut (refl expr x4)
760                                     (refl memory_space x5) (refl block x6)
761                                     (refl int x7) (refl trace x8)))
762                                  ?)))))))))))))))).
763##[ napply (eval_lvalue_ind x1 x2 x3 (λa,psp,loc,ofs,tr,e. ∀e1:eq ? x4 a. ∀e2:eq ? x5 psp. ∀e3:eq ? x6 loc. ∀e4:eq ? x7 ofs. ∀e5:eq ? x8 tr. P a psp loc ofs tr) … Hterm);
764  ##[ napply H1 ##| napply H2 ##| napply H3 ##| napply H4 ##| napply H5 ##]
765##| ##*: ##skip
766##] nqed.
767
768nlet rec eval_expr_ind2 (ge:genv) (e:env) (m:mem)
769  (P:∀a,v,tr. eval_expr ge e m a v tr → Prop)
770  (Q:∀a,psp,loc,ofs,tr. eval_lvalue ge e m a psp loc ofs tr → Prop)
771  (eci:∀i,ty. P ??? (eval_Econst_int ge e m i ty))
772  (ecF:∀f,ty. P ??? (eval_Econst_float ge e m f ty))
773  (elv:∀a,ty,psp,loc,ofs,v,tr,H1,H2. Q (Expr a ty) psp loc ofs tr H1 → P ??? (eval_Elvalue ge e m a ty psp loc ofs v tr H1 H2))
774  (ead:∀a,ty,psp,loc,ofs,tr,H. Q a psp loc ofs tr H → P ??? (eval_Eaddrof ge e m a ty psp loc ofs tr H))
775  (esz:∀ty',ty. P ??? (eval_Esizeof ge e m ty' ty))
776  (eun:∀op,a,ty,v1,v,tr,H1,H2. P a v1 tr H1 → P ??? (eval_Eunop ge e m op a ty v1 v tr H1 H2))
777  (ebi:∀op,a1,a2,ty,v1,v2,v,tr1,tr2,H1,H2,H3. P a1 v1 tr1 H1 → P a2 v2 tr2 H2 → P ??? (eval_Ebinop ge e m op a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3))
778  (ect:∀a1,a2,a3,ty,v1,v2,tr1,tr2,H1,H2,H3. P a1 v1 tr1 H1 → P a2 v2 tr2 H3 → P ??? (eval_Econdition_true ge e m a1 a2 a3 ty v1 v2 tr1 tr2 H1 H2 H3))
779  (ecf:∀a1,a2,a3,ty,v1,v3,tr1,tr2,H1,H2,H3. P a1 v1 tr1 H1 → P a3 v3 tr2 H3 → P ??? (eval_Econdition_false ge e m a1 a2 a3 ty v1 v3 tr1 tr2 H1 H2 H3))
780  (eo1:∀a1,a2,ty,v1,tr,H1,H2. P a1 v1 tr H1 → P ??? (eval_Eorbool_1 ge e m a1 a2 ty v1 tr H1 H2))
781  (eo2:∀a1,a2,ty,v1,v2,v,tr1,tr2,H1,H2,H3,H4. P a1 v1 tr1 H1 → P a2 v2 tr2 H3 → P ??? (eval_Eorbool_2 ge e m a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4))
782  (ea1:∀a1,a2,ty,v1,tr,H1,H2. P a1 v1 tr H1 → P ??? (eval_Eandbool_1 ge e m a1 a2 ty v1 tr H1 H2))
783  (ea2:∀a1,a2,ty,v1,v2,v,tr1,tr2,H1,H2,H3,H4. P a1 v1 tr1 H1 → P a2 v2 tr2 H3 → P ??? (eval_Eandbool_2 ge e m a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4))
784  (ecs:∀a,ty,ty',v1,v,tr,H1,H2. P a v1 tr H1 → P ??? (eval_Ecast ge e m a ty ty' v1 v tr H1 H2))
785  (eco:∀a,ty,v,l,tr,H. P a v tr H → P ??? (eval_Ecost ge e m a ty v l tr H))
786  (lvl:∀id,l,ty,H. Q ????? (eval_Evar_local ge e m id l ty H))
787  (lvg:∀id,sp,l,ty,H1,H2. Q ????? (eval_Evar_global ge e m id sp l ty H1 H2))
788  (lde:∀a,ty,psp,l,ofs,tr,H. P a (Vptr psp l ofs) tr H → Q ????? (eval_Ederef ge e m a ty psp l ofs tr H))
789  (lfs:∀a,i,ty,psp,l,ofs,id,fList,delta,tr,H1,H2,H3. Q a psp l ofs tr H1 → Q ????? (eval_Efield_struct ge e m a i ty psp l ofs id fList delta tr H1 H2 H3))
790  (lfu:∀a,i,ty,psp,l,ofs,id,fList,tr,H1,H2. Q a psp l ofs tr H1 → Q ????? (eval_Efield_union ge e m a i ty psp l ofs id fList tr H1 H2))
791 
792  (a:expr) (v:val) (tr:trace) (ev:eval_expr ge e m a v tr) on ev : P a v tr ev ≝
793  match ev with
794  [ eval_Econst_int i ty ⇒ eci i ty
795  | eval_Econst_float f ty ⇒ ecF f ty
796  | eval_Elvalue a ty psp loc ofs v tr H1 H2 ⇒ elv a ty psp loc ofs v tr H1 H2 (eval_lvalue_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu (Expr a ty) psp loc ofs tr H1)
797  | eval_Eaddrof a ty psp loc ofs tr H ⇒ ead a ty psp loc ofs tr H (eval_lvalue_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a psp loc ofs tr H)
798  | eval_Esizeof ty' ty ⇒ esz ty' ty
799  | eval_Eunop op a ty v1 v tr H1 H2 ⇒ eun op a ty v1 v tr H1 H2 (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a v1 tr H1)
800  | eval_Ebinop op a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 ⇒ ebi op a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a1 v1 tr1 H1) (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a2 v2 tr2 H2)
801  | eval_Econdition_true a1 a2 a3 ty v1 v2 tr1 tr2 H1 H2 H3 ⇒ ect a1 a2 a3 ty v1 v2 tr1 tr2 H1 H2 H3 (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a1 v1 tr1 H1) (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a2 v2 tr2 H3)
802  | eval_Econdition_false a1 a2 a3 ty v1 v3 tr1 tr2 H1 H2 H3 ⇒ ecf a1 a2 a3 ty v1 v3 tr1 tr2 H1 H2 H3 (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a1 v1 tr1 H1) (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a3 v3 tr2 H3)
803  | eval_Eorbool_1 a1 a2 ty v1 tr H1 H2 ⇒ eo1 a1 a2 ty v1 tr H1 H2 (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a1 v1 tr H1)
804  | eval_Eorbool_2 a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4 ⇒ eo2 a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4 (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a1 v1 tr1 H1) (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a2 v2 tr2 H3)
805  | eval_Eandbool_1 a1 a2 ty v1 tr H1 H2 ⇒ ea1 a1 a2 ty v1 tr H1 H2 (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a1 v1 tr H1)
806  | eval_Eandbool_2 a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4 ⇒ ea2 a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4 (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a1 v1 tr1 H1) (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a2 v2 tr2 H3)
807  | eval_Ecast a ty ty' v1 v tr H1 H2 ⇒ ecs a ty ty' v1 v tr H1 H2 (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a v1 tr H1)
808  | eval_Ecost a ty v l tr H ⇒ eco a ty v l tr H (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a v tr H)
809  ]
810and eval_lvalue_ind2 (ge:genv) (e:env) (m:mem)
811  (P:∀a,v,tr. eval_expr ge e m a v tr → Prop)
812  (Q:∀a,psp,loc,ofs,tr. eval_lvalue ge e m a psp loc ofs tr → Prop)
813  (eci:∀i,ty. P ??? (eval_Econst_int ge e m i ty))
814  (ecF:∀f,ty. P ??? (eval_Econst_float ge e m f ty))
815  (elv:∀a,ty,psp,loc,ofs,v,tr,H1,H2. Q (Expr a ty) psp loc ofs tr H1 → P ??? (eval_Elvalue ge e m a ty psp loc ofs v tr H1 H2))
816  (ead:∀a,ty,psp,loc,ofs,tr,H. Q a psp loc ofs tr H → P ??? (eval_Eaddrof ge e m a ty psp loc ofs tr H))
817  (esz:∀ty',ty. P ??? (eval_Esizeof ge e m ty' ty))
818  (eun:∀op,a,ty,v1,v,tr,H1,H2. P a v1 tr H1 → P ??? (eval_Eunop ge e m op a ty v1 v tr H1 H2))
819  (ebi:∀op,a1,a2,ty,v1,v2,v,tr1,tr2,H1,H2,H3. P a1 v1 tr1 H1 → P a2 v2 tr2 H2 → P ??? (eval_Ebinop ge e m op a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3))
820  (ect:∀a1,a2,a3,ty,v1,v2,tr1,tr2,H1,H2,H3. P a1 v1 tr1 H1 → P a2 v2 tr2 H3 → P ??? (eval_Econdition_true ge e m a1 a2 a3 ty v1 v2 tr1 tr2 H1 H2 H3))
821  (ecf:∀a1,a2,a3,ty,v1,v3,tr1,tr2,H1,H2,H3. P a1 v1 tr1 H1 → P a3 v3 tr2 H3 → P ??? (eval_Econdition_false ge e m a1 a2 a3 ty v1 v3 tr1 tr2 H1 H2 H3))
822  (eo1:∀a1,a2,ty,v1,tr,H1,H2. P a1 v1 tr H1 → P ??? (eval_Eorbool_1 ge e m a1 a2 ty v1 tr H1 H2))
823  (eo2:∀a1,a2,ty,v1,v2,v,tr1,tr2,H1,H2,H3,H4. P a1 v1 tr1 H1 → P a2 v2 tr2 H3 → P ??? (eval_Eorbool_2 ge e m a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4))
824  (ea1:∀a1,a2,ty,v1,tr,H1,H2. P a1 v1 tr H1 → P ??? (eval_Eandbool_1 ge e m a1 a2 ty v1 tr H1 H2))
825  (ea2:∀a1,a2,ty,v1,v2,v,tr1,tr2,H1,H2,H3,H4. P a1 v1 tr1 H1 → P a2 v2 tr2 H3 → P ??? (eval_Eandbool_2 ge e m a1 a2 ty v1 v2 v tr1 tr2 H1 H2 H3 H4))
826  (ecs:∀a,ty,ty',v1,v,tr,H1,H2. P a v1 tr H1 → P ??? (eval_Ecast ge e m a ty ty' v1 v tr H1 H2))
827  (eco:∀a,ty,v,l,tr,H. P a v tr H → P ??? (eval_Ecost ge e m a ty v l tr H))
828  (lvl:∀id,l,ty,H. Q ????? (eval_Evar_local ge e m id l ty H))
829  (lvg:∀id,sp,l,ty,H1,H2. Q ????? (eval_Evar_global ge e m id sp l ty H1 H2))
830  (lde:∀a,ty,psp,l,ofs,tr,H. P a (Vptr psp l ofs) tr H → Q ????? (eval_Ederef ge e m a ty psp l ofs tr H))
831  (lfs:∀a,i,ty,psp,l,ofs,id,fList,delta,tr,H1,H2,H3. Q a psp l ofs tr H1 → Q ????? (eval_Efield_struct ge e m a i ty psp l ofs id fList delta tr H1 H2 H3))
832  (lfu:∀a,i,ty,psp,l,ofs,id,fList,tr,H1,H2. Q a psp l ofs tr H1 → Q ????? (eval_Efield_union ge e m a i ty psp l ofs id fList tr H1 H2))
833  (a:expr) (psp:memory_space) (loc:block) (ofs:int) (tr:trace) (ev:eval_lvalue ge e m a psp loc ofs tr) on ev : Q a psp loc ofs tr ev ≝
834  match ev with
835  [ eval_Evar_local id l ty H ⇒ lvl id l ty H
836  | eval_Evar_global id sp l ty H1 H2 ⇒ lvg id sp l ty H1 H2
837  | eval_Ederef a ty psp l ofs tr H ⇒ lde a ty psp l ofs tr H (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a (Vptr psp l ofs) tr H)
838  | eval_Efield_struct a i ty psp l ofs id fList delta tr H1 H2 H3 ⇒ lfs a i ty psp l ofs id fList delta tr H1 H2 H3 (eval_lvalue_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a psp l ofs tr H1)
839  | eval_Efield_union a i ty psp l ofs id fList tr H1 H2 ⇒ lfu a i ty psp l ofs id fList tr H1 H2 (eval_lvalue_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu a psp l ofs tr H1)
840  ].
841
842ndefinition combined_expr_lvalue_ind ≝
843λge,e,m,P,Q,eci,ecF,elv,ead,esz,eun,ebi,ect,ecf,eo1,eo2,ea1,ea2,ecs,eco,lvl,lvg,lde,lfs,lfu. 
844conj ??
845  (eval_expr_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu)
846  (eval_lvalue_ind2 ge e m P Q eci ecF elv ead esz eun ebi ect ecf eo1 eo2 ea1 ea2 ecs eco lvl lvg lde lfs lfu).
847
848(* * [eval_lvalue ge e m a b ofs] defines the evaluation of expression [a]
849  in l-value position.  The result is the memory location [b, ofs]
850  that contains the value of the expression [a]. *)
851
852(*
853Scheme eval_expr_ind22 := Minimality for eval_expr Sort Prop
854  with eval_lvalue_ind2 := Minimality for eval_lvalue Sort Prop.
855*)
856
857(* * [eval_exprlist ge e m al vl] evaluates a list of r-value
858  expressions [al] to their values [vl]. *)
859
860ninductive eval_exprlist (ge:genv) (e:env) (m:mem) : list expr → list val → trace → Prop ≝
861  | eval_Enil:
862      eval_exprlist ge e m (nil ?) (nil ?) E0
863  | eval_Econs:   ∀a,bl,v,vl,tr1,tr2.
864      eval_expr ge e m a v tr1 →
865      eval_exprlist ge e m bl vl tr2 →
866      eval_exprlist ge e m (a :: bl) (v :: vl) (tr1⧺tr2).
867
868(*End EXPR.*)
869
870(* * ** Transition semantics for statements and functions *)
871
872(* * Continuations *)
873
874ninductive cont: Type :=
875  | Kstop: cont
876  | Kseq: statement -> cont -> cont
877       (**r [Kseq s2 k] = after [s1] in [s1;s2] *)
878  | Kwhile: expr -> statement -> cont -> cont
879       (**r [Kwhile e s k] = after [s] in [while (e) s] *)
880  | Kdowhile: expr -> statement -> cont -> cont
881       (**r [Kdowhile e s k] = after [s] in [do s while (e)] *)
882  | Kfor2: expr -> statement -> statement -> cont -> cont
883       (**r [Kfor2 e2 e3 s k] = after [s] in [for(e1;e2;e3) s] *)
884  | Kfor3: expr -> statement -> statement -> cont -> cont
885       (**r [Kfor3 e2 e3 s k] = after [e3] in [for(e1;e2;e3) s] *)
886  | Kswitch: cont -> cont
887       (**r catches [break] statements arising out of [switch] *)
888  | Kcall: option (memory_space × block × int × type) ->   (**r where to store result *)
889           function ->                      (**r calling function *)
890           env ->                           (**r local env of calling function *)
891           cont -> cont.
892
893(* * Pop continuation until a call or stop *)
894
895nlet rec call_cont (k: cont) : cont :=
896  match k with
897  [ Kseq s k => call_cont k
898  | Kwhile e s k => call_cont k
899  | Kdowhile e s k => call_cont k
900  | Kfor2 e2 e3 s k => call_cont k
901  | Kfor3 e2 e3 s k => call_cont k
902  | Kswitch k => call_cont k
903  | _ => k
904  ].
905
906ndefinition is_call_cont : cont → Prop ≝ λk.
907  match k with
908  [ Kstop => True
909  | Kcall _ _ _ _ => True
910  | _ => False
911  ].
912
913(* * States *)
914
915ninductive state: Type :=
916  | State:
917      ∀f: function.
918      ∀s: statement.
919      ∀k: cont.
920      ∀e: env.
921      ∀m: mem.  state
922  | Callstate:
923      ∀fd: fundef.
924      ∀args: list val.
925      ∀k: cont.
926      ∀m: mem. state
927  | Returnstate:
928      ∀res: val.
929      ∀k: cont.
930      ∀m: mem. state.
931                 
932(* * Find the statement and manufacture the continuation
933  corresponding to a label *)
934
935nlet rec find_label (lbl: label) (s: statement) (k: cont)
936                    on s: option (statement × cont) :=
937  match s with
938  [ Ssequence s1 s2 =>
939      match find_label lbl s1 (Kseq s2 k) with
940      [ Some sk => Some ? sk
941      | None => find_label lbl s2 k
942      ]
943  | Sifthenelse a s1 s2 =>
944      match find_label lbl s1 k with
945      [ Some sk => Some ? sk
946      | None => find_label lbl s2 k
947      ]
948  | Swhile a s1 =>
949      find_label lbl s1 (Kwhile a s1 k)
950  | Sdowhile a s1 =>
951      find_label lbl s1 (Kdowhile a s1 k)
952  | Sfor a1 a2 a3 s1 =>
953      match find_label lbl a1 (Kseq (Sfor Sskip a2 a3 s1) k) with
954      [ Some sk => Some ? sk
955      | None =>
956          match find_label lbl s1 (Kfor2 a2 a3 s1 k) with
957          [ Some sk => Some ? sk
958          | None => find_label lbl a3 (Kfor3 a2 a3 s1 k)
959          ]
960      ]
961  | Sswitch e sl =>
962      find_label_ls lbl sl (Kswitch k)
963  | Slabel lbl' s' =>
964      match ident_eq lbl lbl' with
965      [ inl _ ⇒ Some ? 〈s', k〉
966      | inr _ ⇒ find_label lbl s' k
967      ]
968  | _ => None ?
969  ]
970
971and find_label_ls (lbl: label) (sl: labeled_statements) (k: cont)
972                    on sl: option (statement × cont) :=
973  match sl with
974  [ LSdefault s => find_label lbl s k
975  | LScase _ s sl' =>
976      match find_label lbl s (Kseq (seq_of_labeled_statement sl') k) with
977      [ Some sk => Some ? sk
978      | None => find_label_ls lbl sl' k
979      ]
980  ].
981
982(* * Transition relation *)
983
984(* Strip off outer pointer for use when comparing function types. *)
985ndefinition fun_typeof ≝
986λe. match typeof e with
987[ Tvoid ⇒ Tvoid
988| Tint a b ⇒ Tint a b
989| Tfloat a ⇒ Tfloat a
990| Tpointer _ ty ⇒ ty
991| Tarray a b c ⇒ Tarray a b c
992| Tfunction a b ⇒ Tfunction a b
993| Tstruct a b ⇒ Tstruct a b
994| Tunion a b ⇒ Tunion a b
995| Tcomp_ptr a ⇒ Tcomp_ptr a
996].
997
998(* XXX: note that cost labels in exprs expose a particular eval order. *)
999
1000ninductive step (ge:genv) : state → trace → state → Prop ≝
1001
1002  | step_assign:   ∀f,a1,a2,k,e,m,psp,loc,ofs,v2,m',tr1,tr2.
1003      eval_lvalue ge e m a1 psp loc ofs tr1 →
1004      eval_expr ge e m a2 v2 tr2 →
1005      store_value_of_type (typeof a1) m psp loc ofs v2 = Some ? m' →
1006      step ge (State f (Sassign a1 a2) k e m)
1007           (tr1⧺tr2) (State f Sskip k e m')
1008
1009  | step_call_none:   ∀f,a,al,k,e,m,vf,vargs,fd,tr1,tr2.
1010      eval_expr ge e m a vf tr1 →
1011      eval_exprlist ge e m al vargs tr2 →
1012      find_funct ?? ge vf = Some ? fd →
1013      type_of_fundef fd = fun_typeof a →
1014      step ge (State f (Scall (None ?) a al) k e m)
1015           (tr1⧺tr2) (Callstate fd vargs (Kcall (None ?) f e k) m)
1016
1017  | step_call_some:   ∀f,lhs,a,al,k,e,m,psp,loc,ofs,vf,vargs,fd,tr1,tr2,tr3.
1018      eval_lvalue ge e m lhs psp loc ofs tr1 →
1019      eval_expr ge e m a vf tr2 →
1020      eval_exprlist ge e m al vargs tr3 →
1021      find_funct ?? ge vf = Some ? fd →
1022      type_of_fundef fd = fun_typeof a →
1023      step ge (State f (Scall (Some ? lhs) a al) k e m)
1024           (tr1⧺tr2⧺tr3) (Callstate fd vargs (Kcall (Some ? 〈〈〈psp, loc〉, ofs〉, typeof lhs〉) f e k) m)
1025
1026  | step_seq:  ∀f,s1,s2,k,e,m.
1027      step ge (State f (Ssequence s1 s2) k e m)
1028           E0 (State f s1 (Kseq s2 k) e m)
1029  | step_skip_seq: ∀f,s,k,e,m.
1030      step ge (State f Sskip (Kseq s k) e m)
1031           E0 (State f s k e m)
1032  | step_continue_seq: ∀f,s,k,e,m.
1033      step ge (State f Scontinue (Kseq s k) e m)
1034           E0 (State f Scontinue k e m)
1035  | step_break_seq: ∀f,s,k,e,m.
1036      step ge (State f Sbreak (Kseq s k) e m)
1037           E0 (State f Sbreak k e m)
1038
1039  | step_ifthenelse_true:  ∀f,a,s1,s2,k,e,m,v1,tr.
1040      eval_expr ge e m a v1 tr →
1041      is_true v1 (typeof a) →
1042      step ge (State f (Sifthenelse a s1 s2) k e m)
1043           tr (State f s1 k e m)
1044  | step_ifthenelse_false: ∀f,a,s1,s2,k,e,m,v1,tr.
1045      eval_expr ge e m a v1 tr →
1046      is_false v1 (typeof a) →
1047      step ge (State f (Sifthenelse a s1 s2) k e m)
1048           tr (State f s2 k e m)
1049
1050  | step_while_false: ∀f,a,s,k,e,m,v,tr.
1051      eval_expr ge e m a v tr →
1052      is_false v (typeof a) →
1053      step ge (State f (Swhile a s) k e m)
1054           tr (State f Sskip k e m)
1055  | step_while_true: ∀f,a,s,k,e,m,v,tr.
1056      eval_expr ge e m a v tr →
1057      is_true v (typeof a) →
1058      step ge (State f (Swhile a s) k e m)
1059           tr (State f s (Kwhile a s k) e m)
1060  | step_skip_or_continue_while: ∀f,x,a,s,k,e,m.
1061      x = Sskip ∨ x = Scontinue →
1062      step ge (State f x (Kwhile a s k) e m)
1063           E0 (State f (Swhile a s) k e m)
1064  | step_break_while: ∀f,a,s,k,e,m.
1065      step ge (State f Sbreak (Kwhile a s k) e m)
1066           E0 (State f Sskip k e m)
1067
1068  | step_dowhile: ∀f,a,s,k,e,m.
1069      step ge (State f (Sdowhile a s) k e m)
1070        E0 (State f s (Kdowhile a s k) e m)
1071  | step_skip_or_continue_dowhile_false: ∀f,x,a,s,k,e,m,v,tr.
1072      x = Sskip ∨ x = Scontinue →
1073      eval_expr ge e m a v tr →
1074      is_false v (typeof a) →
1075      step ge (State f x (Kdowhile a s k) e m)
1076           tr (State f Sskip k e m)
1077  | step_skip_or_continue_dowhile_true: ∀f,x,a,s,k,e,m,v,tr.
1078      x = Sskip ∨ x = Scontinue →
1079      eval_expr ge e m a v tr →
1080      is_true v (typeof a) →
1081      step ge (State f x (Kdowhile a s k) e m)
1082           tr (State f (Sdowhile a s) k e m)
1083  | step_break_dowhile: ∀f,a,s,k,e,m.
1084      step ge (State f Sbreak (Kdowhile a s k) e m)
1085           E0 (State f Sskip k e m)
1086
1087  | step_for_start: ∀f,a1,a2,a3,s,k,e,m.
1088      a1 ≠ Sskip →
1089      step ge (State f (Sfor a1 a2 a3 s) k e m)
1090           E0 (State f a1 (Kseq (Sfor Sskip a2 a3 s) k) e m)
1091  | step_for_false: ∀f,a2,a3,s,k,e,m,v,tr.
1092      eval_expr ge e m a2 v tr →
1093      is_false v (typeof a2) →
1094      step ge (State f (Sfor Sskip a2 a3 s) k e m)
1095           tr (State f Sskip k e m)
1096  | step_for_true: ∀f,a2,a3,s,k,e,m,v,tr.
1097      eval_expr ge e m a2 v tr →
1098      is_true v (typeof a2) →
1099      step ge (State f (Sfor Sskip a2 a3 s) k e m)
1100           tr (State f s (Kfor2 a2 a3 s k) e m)
1101  | step_skip_or_continue_for2: ∀f,x,a2,a3,s,k,e,m.
1102      x = Sskip ∨ x = Scontinue →
1103      step ge (State f x (Kfor2 a2 a3 s k) e m)
1104           E0 (State f a3 (Kfor3 a2 a3 s k) e m)
1105  | step_break_for2: ∀f,a2,a3,s,k,e,m.
1106      step ge (State f Sbreak (Kfor2 a2 a3 s k) e m)
1107           E0 (State f Sskip k e m)
1108  | step_skip_for3: ∀f,a2,a3,s,k,e,m.
1109      step ge (State f Sskip (Kfor3 a2 a3 s k) e m)
1110           E0 (State f (Sfor Sskip a2 a3 s) k e m)
1111
1112  | step_return_0: ∀f,k,e,m.
1113      fn_return f = Tvoid →
1114      step ge (State f (Sreturn (None ?)) k e m)
1115           E0 (Returnstate Vundef (call_cont k) (free_list m (blocks_of_env e)))
1116  | step_return_1: ∀f,a,k,e,m,v,tr.
1117      fn_return f ≠ Tvoid →
1118      eval_expr ge e m a v tr →
1119      step ge (State f (Sreturn (Some ? a)) k e m)
1120           tr (Returnstate v (call_cont k) (free_list m (blocks_of_env e)))
1121  | step_skip_call: ∀f,k,e,m.
1122      is_call_cont k →
1123      fn_return f = Tvoid →
1124      step ge (State f Sskip k e m)
1125           E0 (Returnstate Vundef k (free_list m (blocks_of_env e)))
1126
1127  | step_switch: ∀f,a,sl,k,e,m,n,tr.
1128      eval_expr ge e m a (Vint n) tr →
1129      step ge (State f (Sswitch a sl) k e m)
1130           tr (State f (seq_of_labeled_statement (select_switch n sl)) (Kswitch k) e m)
1131  | step_skip_break_switch: ∀f,x,k,e,m.
1132      x = Sskip ∨ x = Sbreak →
1133      step ge (State f x (Kswitch k) e m)
1134           E0 (State f Sskip k e m)
1135  | step_continue_switch: ∀f,k,e,m.
1136      step ge (State f Scontinue (Kswitch k) e m)
1137           E0 (State f Scontinue k e m)
1138
1139  | step_label: ∀f,lbl,s,k,e,m.
1140      step ge (State f (Slabel lbl s) k e m)
1141           E0 (State f s k e m)
1142
1143  | step_goto: ∀f,lbl,k,e,m,s',k'.
1144      find_label lbl (fn_body f) (call_cont k) = Some ? 〈s', k'〉 →
1145      step ge (State f (Sgoto lbl) k e m)
1146           E0 (State f s' k' e m)
1147
1148  | step_internal_function: ∀f,vargs,k,m,e,m1,m2.
1149      alloc_variables empty_env m ((fn_params f) @ (fn_vars f)) e m1 →
1150      bind_parameters e m1 (fn_params f) vargs m2 →
1151      step ge (Callstate (Internal f) vargs k m)
1152           E0 (State f (fn_body f) k e m2)
1153
1154  | step_external_function: ∀id,targs,tres,vargs,k,m,vres,t.
1155      event_match (external_function id targs tres) vargs t vres →
1156      step ge (Callstate (External id targs tres) vargs k m)
1157            t (Returnstate vres k m)
1158
1159  | step_returnstate_0: ∀v,f,e,k,m.
1160      step ge (Returnstate v (Kcall (None ?) f e k) m)
1161           E0 (State f Sskip k e m)
1162
1163  | step_returnstate_1: ∀v,f,e,k,m,m',psp,loc,ofs,ty.
1164      store_value_of_type ty m psp loc ofs v = Some ? m' →
1165      step ge (Returnstate v (Kcall (Some ? 〈〈〈psp,loc〉, ofs〉, ty〉) f e k) m)
1166           E0 (State f Sskip k e m')
1167           
1168  | step_cost: ∀f,lbl,s,k,e,m.
1169      step ge (State f (Scost lbl s) k e m)
1170           (Echarge lbl) (State f s k e m).
1171(*
1172(** * Alternate big-step semantics *)
1173
1174(** ** Big-step semantics for terminating statements and functions *)
1175
1176(** The execution of a statement produces an ``outcome'', indicating
1177  how the execution terminated: either normally or prematurely
1178  through the execution of a [break], [continue] or [return] statement. *)
1179
1180ninductive outcome: Type :=
1181   | Out_break: outcome                 (**r terminated by [break] *)
1182   | Out_continue: outcome              (**r terminated by [continue] *)
1183   | Out_normal: outcome                (**r terminated normally *)
1184   | Out_return: option val -> outcome. (**r terminated by [return] *)
1185
1186ninductive out_normal_or_continue : outcome -> Prop :=
1187  | Out_normal_or_continue_N: out_normal_or_continue Out_normal
1188  | Out_normal_or_continue_C: out_normal_or_continue Out_continue.
1189
1190ninductive out_break_or_return : outcome -> outcome -> Prop :=
1191  | Out_break_or_return_B: out_break_or_return Out_break Out_normal
1192  | Out_break_or_return_R: ∀ov.
1193      out_break_or_return (Out_return ov) (Out_return ov).
1194
1195Definition outcome_switch (out: outcome) : outcome :=
1196  match out with
1197  | Out_break => Out_normal
1198  | o => o
1199  end.
1200
1201Definition outcome_result_value (out: outcome) (t: type) (v: val) : Prop :=
1202  match out, t with
1203  | Out_normal, Tvoid => v = Vundef
1204  | Out_return None, Tvoid => v = Vundef
1205  | Out_return (Some v'), ty => ty <> Tvoid /\ v'=v
1206  | _, _ => False
1207  end.
1208
1209(** [exec_stmt ge e m1 s t m2 out] describes the execution of
1210  the statement [s].  [out] is the outcome for this execution.
1211  [m1] is the initial memory state, [m2] the final memory state.
1212  [t] is the trace of input/output events performed during this
1213  evaluation. *)
1214
1215ninductive exec_stmt: env -> mem -> statement -> trace -> mem -> outcome -> Prop :=
1216  | exec_Sskip:   ∀e,m.
1217      exec_stmt e m Sskip
1218               E0 m Out_normal
1219  | exec_Sassign:   ∀e,m,a1,a2,loc,ofs,v2,m'.
1220      eval_lvalue e m a1 loc ofs ->
1221      eval_expr e m a2 v2 ->
1222      store_value_of_type (typeof a1) m loc ofs v2 = Some m' ->
1223      exec_stmt e m (Sassign a1 a2)
1224               E0 m' Out_normal
1225  | exec_Scall_none:   ∀e,m,a,al,vf,vargs,f,t,m',vres.
1226      eval_expr e m a vf ->
1227      eval_exprlist e m al vargs ->
1228      Genv.find_funct ge vf = Some f ->
1229      type_of_fundef f = typeof a ->
1230      eval_funcall m f vargs t m' vres ->
1231      exec_stmt e m (Scall None a al)
1232                t m' Out_normal
1233  | exec_Scall_some:   ∀e,m,lhs,a,al,loc,ofs,vf,vargs,f,t,m',vres,m''.
1234      eval_lvalue e m lhs loc ofs ->
1235      eval_expr e m a vf ->
1236      eval_exprlist e m al vargs ->
1237      Genv.find_funct ge vf = Some f ->
1238      type_of_fundef f = typeof a ->
1239      eval_funcall m f vargs t m' vres ->
1240      store_value_of_type (typeof lhs) m' loc ofs vres = Some m'' ->
1241      exec_stmt e m (Scall (Some lhs) a al)
1242                t m'' Out_normal
1243  | exec_Sseq_1:   ∀e,m,s1,s2,t1,m1,t2,m2,out.
1244      exec_stmt e m s1 t1 m1 Out_normal ->
1245      exec_stmt e m1 s2 t2 m2 out ->
1246      exec_stmt e m (Ssequence s1 s2)
1247                (t1 ** t2) m2 out
1248  | exec_Sseq_2:   ∀e,m,s1,s2,t1,m1,out.
1249      exec_stmt e m s1 t1 m1 out ->
1250      out <> Out_normal ->
1251      exec_stmt e m (Ssequence s1 s2)
1252                t1 m1 out
1253  | exec_Sifthenelse_true: ∀e,m,a,s1,s2,v1,t,m',out.
1254      eval_expr e m a v1 ->
1255      is_true v1 (typeof a) ->
1256      exec_stmt e m s1 t m' out ->
1257      exec_stmt e m (Sifthenelse a s1 s2)
1258                t m' out
1259  | exec_Sifthenelse_false: ∀e,m,a,s1,s2,v1,t,m',out.
1260      eval_expr e m a v1 ->
1261      is_false v1 (typeof a) ->
1262      exec_stmt e m s2 t m' out ->
1263      exec_stmt e m (Sifthenelse a s1 s2)
1264                t m' out
1265  | exec_Sreturn_none:   ∀e,m.
1266      exec_stmt e m (Sreturn None)
1267               E0 m (Out_return None)
1268  | exec_Sreturn_some: ∀e,m,a,v.
1269      eval_expr e m a v ->
1270      exec_stmt e m (Sreturn (Some a))
1271               E0 m (Out_return (Some v))
1272  | exec_Sbreak:   ∀e,m.
1273      exec_stmt e m Sbreak
1274               E0 m Out_break
1275  | exec_Scontinue:   ∀e,m.
1276      exec_stmt e m Scontinue
1277               E0 m Out_continue
1278  | exec_Swhile_false: ∀e,m,a,s,v.
1279      eval_expr e m a v ->
1280      is_false v (typeof a) ->
1281      exec_stmt e m (Swhile a s)
1282               E0 m Out_normal
1283  | exec_Swhile_stop: ∀e,m,a,v,s,t,m',out',out.
1284      eval_expr e m a v ->
1285      is_true v (typeof a) ->
1286      exec_stmt e m s t m' out' ->
1287      out_break_or_return out' out ->
1288      exec_stmt e m (Swhile a s)
1289                t m' out
1290  | exec_Swhile_loop: ∀e,m,a,s,v,t1,m1,out1,t2,m2,out.
1291      eval_expr e m a v ->
1292      is_true v (typeof a) ->
1293      exec_stmt e m s t1 m1 out1 ->
1294      out_normal_or_continue out1 ->
1295      exec_stmt e m1 (Swhile a s) t2 m2 out ->
1296      exec_stmt e m (Swhile a s)
1297                (t1 ** t2) m2 out
1298  | exec_Sdowhile_false: ∀e,m,s,a,t,m1,out1,v.
1299      exec_stmt e m s t m1 out1 ->
1300      out_normal_or_continue out1 ->
1301      eval_expr e m1 a v ->
1302      is_false v (typeof a) ->
1303      exec_stmt e m (Sdowhile a s)
1304                t m1 Out_normal
1305  | exec_Sdowhile_stop: ∀e,m,s,a,t,m1,out1,out.
1306      exec_stmt e m s t m1 out1 ->
1307      out_break_or_return out1 out ->
1308      exec_stmt e m (Sdowhile a s)
1309                t m1 out
1310  | exec_Sdowhile_loop: ∀e,m,s,a,m1,m2,t1,t2,out,out1,v.
1311      exec_stmt e m s t1 m1 out1 ->
1312      out_normal_or_continue out1 ->
1313      eval_expr e m1 a v ->
1314      is_true v (typeof a) ->
1315      exec_stmt e m1 (Sdowhile a s) t2 m2 out ->
1316      exec_stmt e m (Sdowhile a s)
1317                (t1 ** t2) m2 out
1318  | exec_Sfor_start: ∀e,m,s,a1,a2,a3,out,m1,m2,t1,t2.
1319      a1 <> Sskip ->
1320      exec_stmt e m a1 t1 m1 Out_normal ->
1321      exec_stmt e m1 (Sfor Sskip a2 a3 s) t2 m2 out ->
1322      exec_stmt e m (Sfor a1 a2 a3 s)
1323                (t1 ** t2) m2 out
1324  | exec_Sfor_false: ∀e,m,s,a2,a3,v.
1325      eval_expr e m a2 v ->
1326      is_false v (typeof a2) ->
1327      exec_stmt e m (Sfor Sskip a2 a3 s)
1328               E0 m Out_normal
1329  | exec_Sfor_stop: ∀e,m,s,a2,a3,v,m1,t,out1,out.
1330      eval_expr e m a2 v ->
1331      is_true v (typeof a2) ->
1332      exec_stmt e m s t m1 out1 ->
1333      out_break_or_return out1 out ->
1334      exec_stmt e m (Sfor Sskip a2 a3 s)
1335                t m1 out
1336  | exec_Sfor_loop: ∀e,m,s,a2,a3,v,m1,m2,m3,t1,t2,t3,out1,out.
1337      eval_expr e m a2 v ->
1338      is_true v (typeof a2) ->
1339      exec_stmt e m s t1 m1 out1 ->
1340      out_normal_or_continue out1 ->
1341      exec_stmt e m1 a3 t2 m2 Out_normal ->
1342      exec_stmt e m2 (Sfor Sskip a2 a3 s) t3 m3 out ->
1343      exec_stmt e m (Sfor Sskip a2 a3 s)
1344                (t1 ** t2 ** t3) m3 out
1345  | exec_Sswitch:   ∀e,m,a,t,n,sl,m1,out.
1346      eval_expr e m a (Vint n) ->
1347      exec_stmt e m (seq_of_labeled_statement (select_switch n sl)) t m1 out ->
1348      exec_stmt e m (Sswitch a sl)
1349                t m1 (outcome_switch out)
1350
1351(** [eval_funcall m1 fd args t m2 res] describes the invocation of
1352  function [fd] with arguments [args].  [res] is the value returned
1353  by the call.  *)
1354
1355with eval_funcall: mem -> fundef -> list val -> trace -> mem -> val -> Prop :=
1356  | eval_funcall_internal: ∀m,f,vargs,t,e,m1,m2,m3,out,vres.
1357      alloc_variables empty_env m (f.(fn_params) ++ f.(fn_vars)) e m1 ->
1358      bind_parameters e m1 f.(fn_params) vargs m2 ->
1359      exec_stmt e m2 f.(fn_body) t m3 out ->
1360      outcome_result_value out f.(fn_return) vres ->
1361      eval_funcall m (Internal f) vargs t (Mem.free_list m3 (blocks_of_env e)) vres
1362  | eval_funcall_external: ∀m,id,targs,tres,vargs,t,vres.
1363      event_match (external_function id targs tres) vargs t vres ->
1364      eval_funcall m (External id targs tres) vargs t m vres.
1365
1366Scheme exec_stmt_ind2 := Minimality for exec_stmt Sort Prop
1367  with eval_funcall_ind2 := Minimality for eval_funcall Sort Prop.
1368
1369(** ** Big-step semantics for diverging statements and functions *)
1370
1371(** Coinductive semantics for divergence.
1372  [execinf_stmt ge e m s t] holds if the execution of statement [s]
1373  diverges, i.e. loops infinitely.  [t] is the possibly infinite
1374  trace of observable events performed during the execution. *)
1375
1376Coninductive execinf_stmt: env -> mem -> statement -> traceinf -> Prop :=
1377  | execinf_Scall_none:   ∀e,m,a,al,vf,vargs,f,t.
1378      eval_expr e m a vf ->
1379      eval_exprlist e m al vargs ->
1380      Genv.find_funct ge vf = Some f ->
1381      type_of_fundef f = typeof a ->
1382      evalinf_funcall m f vargs t ->
1383      execinf_stmt e m (Scall None a al) t
1384  | execinf_Scall_some:   ∀e,m,lhs,a,al,loc,ofs,vf,vargs,f,t.
1385      eval_lvalue e m lhs loc ofs ->
1386      eval_expr e m a vf ->
1387      eval_exprlist e m al vargs ->
1388      Genv.find_funct ge vf = Some f ->
1389      type_of_fundef f = typeof a ->
1390      evalinf_funcall m f vargs t ->
1391      execinf_stmt e m (Scall (Some lhs) a al) t
1392  | execinf_Sseq_1:   ∀e,m,s1,s2,t.
1393      execinf_stmt e m s1 t ->
1394      execinf_stmt e m (Ssequence s1 s2) t
1395  | execinf_Sseq_2:   ∀e,m,s1,s2,t1,m1,t2.
1396      exec_stmt e m s1 t1 m1 Out_normal ->
1397      execinf_stmt e m1 s2 t2 ->
1398      execinf_stmt e m (Ssequence s1 s2) (t1 *** t2)
1399  | execinf_Sifthenelse_true: ∀e,m,a,s1,s2,v1,t.
1400      eval_expr e m a v1 ->
1401      is_true v1 (typeof a) ->
1402      execinf_stmt e m s1 t ->
1403      execinf_stmt e m (Sifthenelse a s1 s2) t
1404  | execinf_Sifthenelse_false: ∀e,m,a,s1,s2,v1,t.
1405      eval_expr e m a v1 ->
1406      is_false v1 (typeof a) ->
1407      execinf_stmt e m s2 t ->
1408      execinf_stmt e m (Sifthenelse a s1 s2) t
1409  | execinf_Swhile_body: ∀e,m,a,v,s,t.
1410      eval_expr e m a v ->
1411      is_true v (typeof a) ->
1412      execinf_stmt e m s t ->
1413      execinf_stmt e m (Swhile a s) t
1414  | execinf_Swhile_loop: ∀e,m,a,s,v,t1,m1,out1,t2.
1415      eval_expr e m a v ->
1416      is_true v (typeof a) ->
1417      exec_stmt e m s t1 m1 out1 ->
1418      out_normal_or_continue out1 ->
1419      execinf_stmt e m1 (Swhile a s) t2 ->
1420      execinf_stmt e m (Swhile a s) (t1 *** t2)
1421  | execinf_Sdowhile_body: ∀e,m,s,a,t.
1422      execinf_stmt e m s t ->
1423      execinf_stmt e m (Sdowhile a s) t
1424  | execinf_Sdowhile_loop: ∀e,m,s,a,m1,t1,t2,out1,v.
1425      exec_stmt e m s t1 m1 out1 ->
1426      out_normal_or_continue out1 ->
1427      eval_expr e m1 a v ->
1428      is_true v (typeof a) ->
1429      execinf_stmt e m1 (Sdowhile a s) t2 ->
1430      execinf_stmt e m (Sdowhile a s) (t1 *** t2)
1431  | execinf_Sfor_start_1: ∀e,m,s,a1,a2,a3,t.
1432      execinf_stmt e m a1 t ->
1433      execinf_stmt e m (Sfor a1 a2 a3 s) t
1434  | execinf_Sfor_start_2: ∀e,m,s,a1,a2,a3,m1,t1,t2.
1435      a1 <> Sskip ->
1436      exec_stmt e m a1 t1 m1 Out_normal ->
1437      execinf_stmt e m1 (Sfor Sskip a2 a3 s) t2 ->
1438      execinf_stmt e m (Sfor a1 a2 a3 s) (t1 *** t2)
1439  | execinf_Sfor_body: ∀e,m,s,a2,a3,v,t.
1440      eval_expr e m a2 v ->
1441      is_true v (typeof a2) ->
1442      execinf_stmt e m s t ->
1443      execinf_stmt e m (Sfor Sskip a2 a3 s) t
1444  | execinf_Sfor_next: ∀e,m,s,a2,a3,v,m1,t1,t2,out1.
1445      eval_expr e m a2 v ->
1446      is_true v (typeof a2) ->
1447      exec_stmt e m s t1 m1 out1 ->
1448      out_normal_or_continue out1 ->
1449      execinf_stmt e m1 a3 t2 ->
1450      execinf_stmt e m (Sfor Sskip a2 a3 s) (t1 *** t2)
1451  | execinf_Sfor_loop: ∀e,m,s,a2,a3,v,m1,m2,t1,t2,t3,out1.
1452      eval_expr e m a2 v ->
1453      is_true v (typeof a2) ->
1454      exec_stmt e m s t1 m1 out1 ->
1455      out_normal_or_continue out1 ->
1456      exec_stmt e m1 a3 t2 m2 Out_normal ->
1457      execinf_stmt e m2 (Sfor Sskip a2 a3 s) t3 ->
1458      execinf_stmt e m (Sfor Sskip a2 a3 s) (t1 *** t2 *** t3)
1459  | execinf_Sswitch:   ∀e,m,a,t,n,sl.
1460      eval_expr e m a (Vint n) ->
1461      execinf_stmt e m (seq_of_labeled_statement (select_switch n sl)) t ->
1462      execinf_stmt e m (Sswitch a sl) t
1463
1464(** [evalinf_funcall ge m fd args t] holds if the invocation of function
1465    [fd] on arguments [args] diverges, with observable trace [t]. *)
1466
1467with evalinf_funcall: mem -> fundef -> list val -> traceinf -> Prop :=
1468  | evalinf_funcall_internal: ∀m,f,vargs,t,e,m1,m2.
1469      alloc_variables empty_env m (f.(fn_params) ++ f.(fn_vars)) e m1 ->
1470      bind_parameters e m1 f.(fn_params) vargs m2 ->
1471      execinf_stmt e m2 f.(fn_body) t ->
1472      evalinf_funcall m (Internal f) vargs t.
1473
1474End SEMANTICS.
1475*)
1476(* * * Whole-program semantics *)
1477
1478(* * Execution of whole programs are described as sequences of transitions
1479  from an initial state to a final state.  An initial state is a [Callstate]
1480  corresponding to the invocation of the ``main'' function of the program
1481  without arguments and with an empty continuation. *)
1482
1483ninductive initial_state (p: program): state -> Prop :=
1484  | initial_state_intro: ∀b,f.
1485      let ge := globalenv Genv ?? p in
1486      let m0 := init_mem Genv ?? p in
1487      find_symbol ?? ge (prog_main ?? p) = Some ? 〈Code,b〉 ->
1488      find_funct_ptr ?? ge b = Some ? f ->
1489      initial_state p (Callstate f (nil ?) Kstop m0).
1490
1491(* * A final state is a [Returnstate] with an empty continuation. *)
1492
1493ninductive final_state: state -> int -> Prop :=
1494  | final_state_intro: ∀r,m.
1495      final_state (Returnstate (Vint r) Kstop m) r.
1496
1497(* * Execution of a whole program: [exec_program p beh]
1498  holds if the application of [p]'s main function to no arguments
1499  in the initial memory state for [p] has [beh] as observable
1500  behavior. *)
1501
1502ndefinition exec_program : program → program_behavior → Prop ≝ λp,beh.
1503  program_behaves (mk_transrel ?? step) (initial_state p) final_state (globalenv ??? p) beh.
1504(*
1505(** Big-step execution of a whole program.  *)
1506
1507ninductive bigstep_program_terminates (p: program): trace -> int -> Prop :=
1508  | bigstep_program_terminates_intro: ∀b,f,m1,t,r.
1509      let ge := Genv.globalenv p in
1510      let m0 := Genv.init_mem p in
1511      Genv.find_symbol ge p.(prog_main) = Some b ->
1512      Genv.find_funct_ptr ge b = Some f ->
1513      eval_funcall ge m0 f nil t m1 (Vint r) ->
1514      bigstep_program_terminates p t r.
1515
1516ninductive bigstep_program_diverges (p: program): traceinf -> Prop :=
1517  | bigstep_program_diverges_intro: ∀b,f,t.
1518      let ge := Genv.globalenv p in
1519      let m0 := Genv.init_mem p in
1520      Genv.find_symbol ge p.(prog_main) = Some b ->
1521      Genv.find_funct_ptr ge b = Some f ->
1522      evalinf_funcall ge m0 f nil t ->
1523      bigstep_program_diverges p t.
1524
1525(** * Implication from big-step semantics to transition semantics *)
1526
1527Section BIGSTEP_TO_TRANSITIONS.
1528
1529Variable prog: program.
1530Let ge : genv := Genv.globalenv prog.
1531
1532Definition exec_stmt_eval_funcall_ind
1533  (PS: env -> mem -> statement -> trace -> mem -> outcome -> Prop)
1534  (PF: mem -> fundef -> list val -> trace -> mem -> val -> Prop) :=
1535  fun a b c d e f g h i j k l m n o p q r s t u v w x y =>
1536  conj (exec_stmt_ind2 ge PS PF a b c d e f g h i j k l m n o p q r s t u v w x y)
1537       (eval_funcall_ind2 ge PS PF a b c d e f g h i j k l m n o p q r s t u v w x y).
1538
1539ninductive outcome_state_match
1540       (e: env) (m: mem) (f: function) (k: cont): outcome -> state -> Prop :=
1541  | osm_normal:
1542      outcome_state_match e m f k Out_normal (State f Sskip k e m)
1543  | osm_break:
1544      outcome_state_match e m f k Out_break (State f Sbreak k e m)
1545  | osm_continue:
1546      outcome_state_match e m f k Out_continue (State f Scontinue k e m)
1547  | osm_return_none: ∀k'.
1548      call_cont k' = call_cont k ->
1549      outcome_state_match e m f k
1550        (Out_return None) (State f (Sreturn None) k' e m)
1551  | osm_return_some: ∀a,v,k'.
1552      call_cont k' = call_cont k ->
1553      eval_expr ge e m a v ->
1554      outcome_state_match e m f k
1555        (Out_return (Some v)) (State f (Sreturn (Some a)) k' e m).
1556
1557Lemma is_call_cont_call_cont:
1558  ∀k. is_call_cont k -> call_cont k = k.
1559Proof.
1560  destruct k; simpl; intros; contradiction || auto.
1561Qed.
1562
1563Lemma exec_stmt_eval_funcall_steps:
1564  (∀e,m,s,t,m',out.
1565   exec_stmt ge e m s t m' out ->
1566   ∀f,k. exists S,
1567   star step ge (State f s k e m) t S
1568   /\ outcome_state_match e m' f k out S)
1569/\
1570  (∀m,fd,args,t,m',res.
1571   eval_funcall ge m fd args t m' res ->
1572   ∀k.
1573   is_call_cont k ->
1574   star step ge (Callstate fd args k m) t (Returnstate res k m')).
1575Proof.
1576  apply exec_stmt_eval_funcall_ind; intros.
1577
1578(* skip *)
1579  econstructor; split. apply star_refl. constructor.
1580
1581(* assign *)
1582  econstructor; split. apply star_one. econstructor; eauto. constructor.
1583
1584(* call none *)
1585  econstructor; split.
1586  eapply star_left. econstructor; eauto.
1587  eapply star_right. apply H4. simpl; auto. econstructor. reflexivity. traceEq.
1588  constructor.
1589
1590(* call some *)
1591  econstructor; split.
1592  eapply star_left. econstructor; eauto.
1593  eapply star_right. apply H5. simpl; auto. econstructor; eauto. reflexivity. traceEq.
1594  constructor.
1595
1596(* sequence 2 *)
1597  destruct (H0 f (Kseq s2 k)) as [S1 [A1 B1]]. inv B1.
1598  destruct (H2 f k) as [S2 [A2 B2]].
1599  econstructor; split.
1600  eapply star_left. econstructor.
1601  eapply star_trans. eexact A1.
1602  eapply star_left. constructor. eexact A2.
1603  reflexivity. reflexivity. traceEq.
1604  auto.
1605
1606(* sequence 1 *)
1607  destruct (H0 f (Kseq s2 k)) as [S1 [A1 B1]].
1608  set (S2 :=
1609    match out with
1610    | Out_break => State f Sbreak k e m1
1611    | Out_continue => State f Scontinue k e m1
1612    | _ => S1
1613    end).
1614  exists S2; split.
1615  eapply star_left. econstructor.
1616  eapply star_trans. eexact A1.
1617  unfold S2; inv B1.
1618    congruence.
1619    apply star_one. apply step_break_seq.
1620    apply star_one. apply step_continue_seq.
1621    apply star_refl.
1622    apply star_refl.
1623  reflexivity. traceEq.
1624  unfold S2; inv B1; congruence || econstructor; eauto.
1625
1626(* ifthenelse true *)
1627  destruct (H2 f k) as [S1 [A1 B1]].
1628  exists S1; split.
1629  eapply star_left. eapply step_ifthenelse_true; eauto. eexact A1. traceEq.
1630  auto.
1631
1632(* ifthenelse false *)
1633  destruct (H2 f k) as [S1 [A1 B1]].
1634  exists S1; split.
1635  eapply star_left. eapply step_ifthenelse_false; eauto. eexact A1. traceEq.
1636  auto.
1637
1638(* return none *)
1639  econstructor; split. apply star_refl. constructor. auto.
1640
1641(* return some *)
1642  econstructor; split. apply star_refl. econstructor; eauto.
1643
1644(* break *)
1645  econstructor; split. apply star_refl. constructor.
1646
1647(* continue *)
1648  econstructor; split. apply star_refl. constructor.
1649
1650(* while false *)
1651  econstructor; split.
1652  apply star_one. eapply step_while_false; eauto.
1653  constructor.
1654
1655(* while stop *)
1656  destruct (H2 f (Kwhile a s k)) as [S1 [A1 B1]].
1657  set (S2 :=
1658    match out' with
1659    | Out_break => State f Sskip k e m'
1660    | _ => S1
1661    end).
1662  exists S2; split.
1663  eapply star_left. eapply step_while_true; eauto.
1664  eapply star_trans. eexact A1.
1665  unfold S2. inversion H3; subst.
1666  inv B1. apply star_one. constructor.   
1667  apply star_refl.
1668  reflexivity. traceEq.
1669  unfold S2. inversion H3; subst. constructor. inv B1; econstructor; eauto.
1670
1671(* while loop *)
1672  destruct (H2 f (Kwhile a s k)) as [S1 [A1 B1]].
1673  destruct (H5 f k) as [S2 [A2 B2]].
1674  exists S2; split.
1675  eapply star_left. eapply step_while_true; eauto.
1676  eapply star_trans. eexact A1.
1677  eapply star_left.
1678  inv H3; inv B1; apply step_skip_or_continue_while; auto.
1679  eexact A2.
1680  reflexivity. reflexivity. traceEq.
1681  auto.
1682
1683(* dowhile false *)
1684  destruct (H0 f (Kdowhile a s k)) as [S1 [A1 B1]].
1685  exists (State f Sskip k e m1); split.
1686  eapply star_left. constructor.
1687  eapply star_right. eexact A1.
1688  inv H1; inv B1; eapply step_skip_or_continue_dowhile_false; eauto.
1689  reflexivity. traceEq.
1690  constructor.
1691
1692(* dowhile stop *)
1693  destruct (H0 f (Kdowhile a s k)) as [S1 [A1 B1]].
1694  set (S2 :=
1695    match out1 with
1696    | Out_break => State f Sskip k e m1
1697    | _ => S1
1698    end).
1699  exists S2; split.
1700  eapply star_left. apply step_dowhile.
1701  eapply star_trans. eexact A1.
1702  unfold S2. inversion H1; subst.
1703  inv B1. apply star_one. constructor.
1704  apply star_refl.
1705  reflexivity. traceEq.
1706  unfold S2. inversion H1; subst. constructor. inv B1; econstructor; eauto.
1707
1708(* dowhile loop *)
1709  destruct (H0 f (Kdowhile a s k)) as [S1 [A1 B1]].
1710  destruct (H5 f k) as [S2 [A2 B2]].
1711  exists S2; split.
1712  eapply star_left. apply step_dowhile.
1713  eapply star_trans. eexact A1.
1714  eapply star_left.
1715  inv H1; inv B1; eapply step_skip_or_continue_dowhile_true; eauto.
1716  eexact A2.
1717  reflexivity. reflexivity. traceEq.
1718  auto.
1719
1720(* for start *)
1721  destruct (H1 f (Kseq (Sfor Sskip a2 a3 s) k)) as [S1 [A1 B1]]. inv B1.
1722  destruct (H3 f k) as [S2 [A2 B2]].
1723  exists S2; split.
1724  eapply star_left. apply step_for_start; auto.   
1725  eapply star_trans. eexact A1.
1726  eapply star_left. constructor. eexact A2.
1727  reflexivity. reflexivity. traceEq.
1728  auto.
1729
1730(* for false *)
1731  econstructor; split.
1732  eapply star_one. eapply step_for_false; eauto.
1733  constructor.
1734
1735(* for stop *)
1736  destruct (H2 f (Kfor2 a2 a3 s k)) as [S1 [A1 B1]].
1737  set (S2 :=
1738    match out1 with
1739    | Out_break => State f Sskip k e m1
1740    | _ => S1
1741    end).
1742  exists S2; split.
1743  eapply star_left. eapply step_for_true; eauto.
1744  eapply star_trans. eexact A1.
1745  unfold S2. inversion H3; subst.
1746  inv B1. apply star_one. constructor.
1747  apply star_refl.
1748  reflexivity. traceEq.
1749  unfold S2. inversion H3; subst. constructor. inv B1; econstructor; eauto.
1750
1751(* for loop *)
1752  destruct (H2 f (Kfor2 a2 a3 s k)) as [S1 [A1 B1]].
1753  destruct (H5 f (Kfor3 a2 a3 s k)) as [S2 [A2 B2]]. inv B2.
1754  destruct (H7 f k) as [S3 [A3 B3]].
1755  exists S3; split.
1756  eapply star_left. eapply step_for_true; eauto.
1757  eapply star_trans. eexact A1.
1758  eapply star_trans with (s2 := State f a3 (Kfor3 a2 a3 s k) e m1).
1759  inv H3; inv B1.
1760  apply star_one. constructor. auto.
1761  apply star_one. constructor. auto.
1762  eapply star_trans. eexact A2.
1763  eapply star_left. constructor.
1764  eexact A3.
1765  reflexivity. reflexivity. reflexivity. reflexivity. traceEq.
1766  auto.
1767
1768(* switch *)
1769  destruct (H1 f (Kswitch k)) as [S1 [A1 B1]].
1770  set (S2 :=
1771    match out with
1772    | Out_normal => State f Sskip k e m1
1773    | Out_break => State f Sskip k e m1
1774    | Out_continue => State f Scontinue k e m1
1775    | _ => S1
1776    end).
1777  exists S2; split.
1778  eapply star_left. eapply step_switch; eauto.
1779  eapply star_trans. eexact A1.
1780  unfold S2; inv B1.
1781    apply star_one. constructor. auto.
1782    apply star_one. constructor. auto.
1783    apply star_one. constructor.
1784    apply star_refl.
1785    apply star_refl.
1786  reflexivity. traceEq.
1787  unfold S2. inv B1; simpl; econstructor; eauto.
1788
1789(* call internal *)
1790  destruct (H2 f k) as [S1 [A1 B1]].
1791  eapply star_left. eapply step_internal_function; eauto.
1792  eapply star_right. eexact A1.
1793  inv B1; simpl in H3; try contradiction.
1794  (* Out_normal *)
1795  assert (fn_return f = Tvoid /\ vres = Vundef).
1796    destruct (fn_return f); auto || contradiction.
1797  destruct H5. subst vres. apply step_skip_call; auto.
1798  (* Out_return None *)
1799  assert (fn_return f = Tvoid /\ vres = Vundef).
1800    destruct (fn_return f); auto || contradiction.
1801  destruct H6. subst vres.
1802  rewrite <- (is_call_cont_call_cont k H4). rewrite <- H5.
1803  apply step_return_0; auto.
1804  (* Out_return Some *)
1805  destruct H3. subst vres.
1806  rewrite <- (is_call_cont_call_cont k H4). rewrite <- H5.
1807  eapply step_return_1; eauto.
1808  reflexivity. traceEq.
1809
1810(* call external *)
1811  apply star_one. apply step_external_function; auto.
1812Qed.
1813
1814Lemma exec_stmt_steps:
1815   ∀e,m,s,t,m',out.
1816   exec_stmt ge e m s t m' out ->
1817   ∀f,k. exists S,
1818   star step ge (State f s k e m) t S
1819   /\ outcome_state_match e m' f k out S.
1820Proof (proj1 exec_stmt_eval_funcall_steps).
1821
1822Lemma eval_funcall_steps:
1823   ∀m,fd,args,t,m',res.
1824   eval_funcall ge m fd args t m' res ->
1825   ∀k.
1826   is_call_cont k ->
1827   star step ge (Callstate fd args k m) t (Returnstate res k m').
1828Proof (proj2 exec_stmt_eval_funcall_steps).
1829
1830Definition order (x y: unit) := False.
1831
1832Lemma evalinf_funcall_forever:
1833  ∀m,fd,args,T,k.
1834  evalinf_funcall ge m fd args T ->
1835  forever_N step order ge tt (Callstate fd args k m) T.
1836Proof.
1837  cofix CIH_FUN.
1838  assert (∀e,m,s,T,f,k.
1839          execinf_stmt ge e m s T ->
1840          forever_N step order ge tt (State f s k e m) T).
1841  cofix CIH_STMT.
1842  intros. inv H.
1843
1844(* call none *)
1845  eapply forever_N_plus.
1846  apply plus_one. eapply step_call_none; eauto.
1847  apply CIH_FUN. eauto. traceEq.
1848(* call some *)
1849  eapply forever_N_plus.
1850  apply plus_one. eapply step_call_some; eauto.
1851  apply CIH_FUN. eauto. traceEq.
1852
1853(* seq 1 *)
1854  eapply forever_N_plus.
1855  apply plus_one. econstructor.
1856  apply CIH_STMT; eauto. traceEq.
1857(* seq 2 *)
1858  destruct (exec_stmt_steps _ _ _ _ _ _ H0 f (Kseq s2 k)) as [S1 [A1 B1]].
1859  inv B1.
1860  eapply forever_N_plus.
1861  eapply plus_left. constructor. eapply star_trans. eexact A1.
1862  apply star_one. constructor. reflexivity. reflexivity.
1863  apply CIH_STMT; eauto. traceEq.
1864
1865(* ifthenelse true *)
1866  eapply forever_N_plus.
1867  apply plus_one. eapply step_ifthenelse_true; eauto.
1868  apply CIH_STMT; eauto. traceEq.
1869(* ifthenelse false *)
1870  eapply forever_N_plus.
1871  apply plus_one. eapply step_ifthenelse_false; eauto.
1872  apply CIH_STMT; eauto. traceEq.
1873
1874(* while body *)
1875  eapply forever_N_plus.
1876  eapply plus_one. eapply step_while_true; eauto.
1877  apply CIH_STMT; eauto. traceEq.
1878(* while loop *)
1879  destruct (exec_stmt_steps _ _ _ _ _ _ H2 f (Kwhile a s0 k)) as [S1 [A1 B1]].
1880  eapply forever_N_plus with (s2 := State f (Swhile a s0) k e m1).
1881  eapply plus_left. eapply step_while_true; eauto.
1882  eapply star_right. eexact A1.
1883  inv H3; inv B1; apply step_skip_or_continue_while; auto.
1884  reflexivity. reflexivity.
1885  apply CIH_STMT; eauto. traceEq.
1886
1887(* dowhile body *)
1888  eapply forever_N_plus.
1889  eapply plus_one. eapply step_dowhile.
1890  apply CIH_STMT; eauto.
1891  traceEq.
1892
1893(* dowhile loop *)
1894  destruct (exec_stmt_steps _ _ _ _ _ _ H0 f (Kdowhile a s0 k)) as [S1 [A1 B1]].
1895  eapply forever_N_plus with (s2 := State f (Sdowhile a s0) k e m1).
1896  eapply plus_left. eapply step_dowhile.
1897  eapply star_right. eexact A1.
1898  inv H1; inv B1; eapply step_skip_or_continue_dowhile_true; eauto.
1899  reflexivity. reflexivity.
1900  apply CIH_STMT. eauto.
1901  traceEq.
1902
1903(* for start 1 *)
1904  assert (a1 <> Sskip). red; intros; subst. inv H0.
1905  eapply forever_N_plus.
1906  eapply plus_one. apply step_for_start; auto.
1907  apply CIH_STMT; eauto.
1908  traceEq.
1909
1910(* for start 2 *)
1911  destruct (exec_stmt_steps _ _ _ _ _ _ H1 f (Kseq (Sfor Sskip a2 a3 s0) k)) as [S1 [A1 B1]].
1912  inv B1.
1913  eapply forever_N_plus.
1914  eapply plus_left. eapply step_for_start; eauto.
1915  eapply star_right. eexact A1.
1916  apply step_skip_seq.
1917  reflexivity. reflexivity.
1918  apply CIH_STMT; eauto.
1919  traceEq.
1920
1921(* for body *)
1922  eapply forever_N_plus.
1923  apply plus_one. eapply step_for_true; eauto.
1924  apply CIH_STMT; eauto.
1925  traceEq.
1926
1927(* for next *)
1928  destruct (exec_stmt_steps _ _ _ _ _ _ H2 f (Kfor2 a2 a3 s0 k)) as [S1 [A1 B1]].
1929  eapply forever_N_plus.
1930  eapply plus_left. eapply step_for_true; eauto.
1931  eapply star_trans. eexact A1.
1932  apply star_one.
1933  inv H3; inv B1; apply step_skip_or_continue_for2; auto.
1934  reflexivity. reflexivity.
1935  apply CIH_STMT; eauto.
1936  traceEq.
1937
1938(* for body *)
1939  destruct (exec_stmt_steps _ _ _ _ _ _ H2 f (Kfor2 a2 a3 s0 k)) as [S1 [A1 B1]].
1940  destruct (exec_stmt_steps _ _ _ _ _ _ H4 f (Kfor3 a2 a3 s0 k)) as [S2 [A2 B2]].
1941  inv B2.
1942  eapply forever_N_plus.
1943  eapply plus_left. eapply step_for_true; eauto.
1944  eapply star_trans. eexact A1.
1945  eapply star_left. inv H3; inv B1; apply step_skip_or_continue_for2; auto.
1946  eapply star_right. eexact A2.
1947  constructor.
1948  reflexivity. reflexivity. reflexivity. reflexivity. 
1949  apply CIH_STMT; eauto.
1950  traceEq.
1951
1952(* switch *)
1953  eapply forever_N_plus.
1954  eapply plus_one. eapply step_switch; eauto.
1955  apply CIH_STMT; eauto.
1956  traceEq.
1957
1958(* call internal *)
1959  intros. inv H0.
1960  eapply forever_N_plus.
1961  eapply plus_one. econstructor; eauto.
1962  apply H; eauto.
1963  traceEq.
1964Qed.
1965
1966Theorem bigstep_program_terminates_exec:
1967  ∀t,r. bigstep_program_terminates prog t r -> exec_program prog (Terminates t r).
1968Proof.
1969  intros. inv H. unfold ge0, m0 in *.
1970  econstructor.
1971  econstructor. eauto. eauto.
1972  apply eval_funcall_steps. eauto. red; auto.
1973  econstructor.
1974Qed.
1975
1976Theorem bigstep_program_diverges_exec:
1977  ∀T. bigstep_program_diverges prog T ->
1978  exec_program prog (Reacts T) \/
1979  exists t, exec_program prog (Diverges t) /\ traceinf_prefix t T.
1980Proof.
1981  intros. inv H.
1982  set (st := Callstate f nil Kstop m0).
1983  assert (forever step ge0 st T).
1984    eapply forever_N_forever with (order := order).
1985    red; intros. constructor; intros. red in H. elim H.
1986    eapply evalinf_funcall_forever; eauto.
1987  destruct (forever_silent_or_reactive _ _ _ _ _ _ H)
1988  as [A | [t [s' [T' [B [C D]]]]]].
1989  left. econstructor. econstructor. eauto. eauto. auto.
1990  right. exists t. split.
1991  econstructor. econstructor; eauto. eauto. auto.
1992  subst T. rewrite <- (E0_right t) at 1. apply traceinf_prefix_app. constructor.
1993Qed.
1994
1995End BIGSTEP_TO_TRANSITIONS.
1996
1997
1998
1999*)
2000
2001 
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