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| ID | Project | Category | View Status | Date Submitted | Last Update |
| 0001484 | Frama-C | Plug-in > wp | public | 2013-09-25 15:30 | 2019-10-17 17:11 |
|
| Reporter | virgile | |
| Assigned To | correnson | |
| Priority | normal | Severity | minor | Reproducibility | always |
| Status | resolved | Resolution | fixed | |
| Platform | | OS | | OS Version | |
| Product Version | Frama-C GIT, precise the release id | |
| Target Version | | Fixed in Version | Frama-C 20-Calcium | |
|
| Summary | 0001484: ill-typed alt-ergo proof obligation |
| Description | Using WP with RTE enabled on the attached file results in proof obligations rejected as ill-typed by Alt-Ergo. |
| Steps To Reproduce | frama-c -wp -wp-rte t.c |
| Additional Information | Without rte, everything is fine. With RTE, the resulting proof obligation is the following:
forall x_0 : int.
let x_1 = to_sint32(neqb(0, x_0)) : int in
let x_2 = to_uint8(x_0 - (ite((eqb(0, x_0)), 0, 1))) : int in
is_uint8(x_0) ->
(x_1 <= (2147483648 + x_0)) ->
(x_0 <= (2147483647 + x_1)) ->
is_uint8(x_2) ->
(x_2 <= x_0)
the definition of x_1 is lacking an ite(_,0,1) conversion, as shown in the definition of x_2. x_1 does not appear in the PO without RTE, as it is only used in the (x<=2147483648 + x_0) and x_0 <= (2147483647 + x_1) hypotheses reflecting the RTE-generated hypotheses.
Note that writing the RTE-generated hypotheses in the code (and launching WP without -wp-rte) results in warning cast from (boolean) not yet implemented, and degenerated goals. |
| Tags | No tags attached. |
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| Attached Files |  t.c [^] (165 bytes) 2013-09-25 15:30 [Show Content] [Hide Content]//@ ensures \result <= x;
unsigned char f(unsigned char x) {
/*@ assert rte: signed_overflow: (int)x-(int)((int)x≢0) ≤ 2147483647;
*/
return x-(x!=0);
}
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