diff options
| author | Xavier Leroy <xavier.leroy@inria.fr> | 2016-03-02 10:35:21 +0100 |
|---|---|---|
| committer | Xavier Leroy <xavier.leroy@inria.fr> | 2016-03-02 10:35:21 +0100 |
| commit | 513489eb97c2b99f5ad901a0f26b493e99bbec1a (patch) | |
| tree | 42d5a8af0c7e5f56347bc668386eedb32428201f /cfrontend/ClightBigstep.v | |
| parent | d8740a489984f63864a8e4ff728fb7f3871ecb34 (diff) | |
| download | compcert-kvx-513489eb97c2b99f5ad901a0f26b493e99bbec1a.tar.gz compcert-kvx-513489eb97c2b99f5ad901a0f26b493e99bbec1a.zip | |
Make casts of pointers to _Bool semantically well defined (again).
In compCert 2.5 the semantics of pointer comparisons against the NULL pointer was made more accurate by making it undefined if the pointer is invalid (outside bounds). Technical difficulties prevented this change from being propagated to the semantics of casts from pointer types to the _Bool type, which involves an implicit pointer comparison against NULL. Hence, this kind of casts was temporarily given undefined semantics.
This commit makes pointer-to-_Bool casts semantically defined (again), provided the pointer is valid. This reinstates the equivalence between casts to _Bool and comparisons != 0. The technical difficulties mentioned above came from the translation of assignments in a value context in the SimplExpr pass. The pass was lightly modified to work around the issue.
Diffstat (limited to 'cfrontend/ClightBigstep.v')
| -rw-r--r-- | cfrontend/ClightBigstep.v | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/cfrontend/ClightBigstep.v b/cfrontend/ClightBigstep.v index ee653d50..92457586 100644 --- a/cfrontend/ClightBigstep.v +++ b/cfrontend/ClightBigstep.v @@ -60,11 +60,11 @@ Definition outcome_switch (out: outcome) : outcome := | o => o end. -Definition outcome_result_value (out: outcome) (t: type) (v: val) : Prop := +Definition outcome_result_value (out: outcome) (t: type) (v: val) (m: mem): Prop := match out, t with | Out_normal, Tvoid => v = Vundef | Out_return None, Tvoid => v = Vundef - | Out_return (Some (v',t')), ty => ty <> Tvoid /\ sem_cast v' t' t = Some v + | Out_return (Some (v',t')), ty => ty <> Tvoid /\ sem_cast v' t' t m = Some v | _, _ => False end. @@ -81,7 +81,7 @@ Inductive exec_stmt: env -> temp_env -> mem -> statement -> trace -> temp_env -> | exec_Sassign: forall e le m a1 a2 loc ofs v2 v m', eval_lvalue ge e le m a1 loc ofs -> eval_expr ge e le m a2 v2 -> - sem_cast v2 (typeof a2) (typeof a1) = Some v -> + sem_cast v2 (typeof a2) (typeof a1) m = Some v -> assign_loc ge (typeof a1) m loc ofs v m' -> exec_stmt e le m (Sassign a1 a2) E0 le m' Out_normal @@ -168,7 +168,7 @@ with eval_funcall: mem -> fundef -> list val -> trace -> mem -> val -> Prop := list_norepet (var_names f.(fn_params) ++ var_names f.(fn_vars)) -> bind_parameters ge e m1 f.(fn_params) vargs m2 -> exec_stmt e (create_undef_temps f.(fn_temps)) m2 f.(fn_body) t le m3 out -> - outcome_result_value out f.(fn_return) vres -> + outcome_result_value out f.(fn_return) vres m3 -> Mem.free_list m3 (blocks_of_env ge e) = Some m4 -> eval_funcall m (Internal f) vargs t m4 vres | eval_funcall_external: forall m ef targs tres cconv vargs t vres m', |