Codegen storage markers as assignments to __CPROVER_dead_object #3164
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This changes our handling of storage markers to be marking is-alive only rather than treating StorageLive as creating a new object. That is, object instances are now tied to their Mir-provided declarations (which, at present, only appear once per function). To still account for when Rust scopes deem an object to be alive, we use StorageLive and StorageDead to update `__CPROVER_dead_object`. This (global) variable is used by CBMC's pointer checks to track when a pointer may not be safe to dereference for it could be pointing to an object that no longer is in scope. Resolves: model-checking#3099
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This still requires a fix on the CBMC side for contracts instrumentation not to fail, which is in diffblue/cbmc#8261. |
celinval
reviewed
Apr 26, 2024
| Stmt::skip(location) | ||
| } else { | ||
| Stmt::decl(self.codegen_local(*var_id), None, location) | ||
| let global_dead_object = self.ensure_global_var( |
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Can you please encapsulate this declaration inside the goto bindings create?
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This changes our handling of storage markers to be marking is-alive only rather than treating StorageLive as creating a new object. That is, object instances are now tied to their Mir-provided declarations (which, at present, only appear once per function). To still account for when Rust scopes deem an object to be alive, we use StorageLive and StorageDead to update
__CPROVER_dead_object. This (global) variable is used by CBMC's pointer checks to track when a pointer may not be safe to dereference for it could be pointing to an object that no longer is in scope.Resolves: #3099
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