diff options
Diffstat (limited to 'src/Interpreter.ml')
| -rw-r--r-- | src/Interpreter.ml | 138 |
1 files changed, 88 insertions, 50 deletions
diff --git a/src/Interpreter.ml b/src/Interpreter.ml index 129b856b..4bb449bd 100644 --- a/src/Interpreter.ml +++ b/src/Interpreter.ml @@ -1317,6 +1317,44 @@ let apply_reborrows (reborrows : (V.BorrowId.id * V.BorrowId.id) list) (* Return *) ctx +(** Auxiliary function to prepare reborrowing operations (used when + applying projectors). + + Returns two functions: + - a function to generate fresh re-borrow ids, and register the reborrows + - a function to apply the reborrows in a context + Those functions are of course stateful. + *) +let prepare_reborrows (config : C.config) (allow_reborrows : bool) + (ctx : C.eval_ctx) : + (V.BorrowId.id -> V.BorrowId.id) * (C.eval_ctx -> C.eval_ctx) = + let reborrows : (V.BorrowId.id * V.BorrowId.id) list ref = ref [] in + let borrow_counter = ref ctx.C.borrow_counter in + (* The function to generate and register fresh reborrows *) + let fresh_reborrow (bid : V.BorrowId.id) : V.BorrowId.id = + if allow_reborrows then ( + let bid', cnt' = V.BorrowId.fresh ctx.borrow_counter in + borrow_counter := cnt'; + reborrows := (bid, bid') :: !reborrows; + bid') + else failwith "Unexpected reborrow" + in + (* The function to apply the reborrows in a context *) + let apply_registered_reborrows (ctx : C.eval_ctx) : C.eval_ctx = + match config.C.mode with + | C.ConcreteMode -> + (* Reborrows are introduced when applying projections in symbolic mode *) + assert (!borrow_counter = ctx.C.borrow_counter); + assert (!reborrows = []); + ctx + | C.SymbolicMode -> + (* Update the borrow counter *) + let ctx = { ctx with C.borrow_counter = !borrow_counter } in + (* Apply the reborrows *) + apply_reborrows !reborrows ctx + in + (fresh_reborrow, apply_registered_reborrows) + (** Auxiliary function to end borrows. See [give_back]. When we end a mutable borrow, we need to "give back" the value it contained @@ -1336,15 +1374,12 @@ let give_back_value (config : C.config) (bid : V.BorrowId.id) in (* Whenever giving back symbolic values, they shouldn't contain already ended regions *) let check_symbolic_no_ended = true in - (* We sometimes need to reborrow values while giving a value back due *) - let reborrows : (V.BorrowId.id * V.BorrowId.id) list ref = ref [] in - let borrow_counter = ref ctx.C.borrow_counter in - let fresh_reborrow (bid : V.BorrowId.id) : V.BorrowId.id = - let bid', cnt' = V.BorrowId.fresh ctx.borrow_counter in - borrow_counter := cnt'; - reborrows := (bid, bid') :: !reborrows; - bid' + (* We sometimes need to reborrow values while giving a value back due: prepare that *) + let allow_reborrows = true in + let fresh_reborrow, apply_registered_reborrows = + prepare_reborrows config allow_reborrows ctx in + (* The visitor to give back the values *) let obj = object (self) inherit [_] C.map_eval_ctx as super @@ -1446,21 +1481,7 @@ let give_back_value (config : C.config) (bid : V.BorrowId.id) (* Check we gave back to exactly one loan *) assert !replaced; (* Apply the reborrows *) - let ctx = - match config.C.mode with - | C.ConcreteMode -> - (* Reborrows are introduced when applying projections in symbolic mode *) - assert (!borrow_counter = ctx.C.borrow_counter); - assert (!reborrows = []); - ctx - | C.SymbolicMode -> - (* Update the borrow counter *) - let ctx = { ctx with C.borrow_counter = !borrow_counter } in - (* Apply the reborrows *) - apply_reborrows !reborrows ctx - in - (* Return *) - ctx + apply_registered_reborrows ctx (** Auxiliary function to end borrows. See [give_back]. @@ -2758,39 +2779,23 @@ let expand_symbolic_value_borrow (ended_regions : T.RegionId.set_t) raise Unimplemented | T.Shared -> raise Unimplemented -(** Apply a symbolic expansion to a context, by replacing the original - symbolic value with its expanded value. Is valid only if the expansion - is not a borrow (i.e., an adt...). +(** Auxiliary function. + Apply a symbolic expansion to avalues. *) -let apply_symbolic_expansion_non_borrow (config : C.config) - (original_sv : V.symbolic_value) (expansion : V.typed_value) - (ctx : C.eval_ctx) : C.eval_ctx = - (* [apply_proj_borrows] needs a [fresh_reborrow] function, to generate - fresh identifiers and register reborrows, whenever needed. As we don't - expand borrows, we shouldn't have to apply reborrows. *) - let fresh_reborrow (_ : V.BorrowId.id) : V.BorrowId.id = - failwith "Unexpected reborrow" - in - (* For the projectors: it might happen that the expansion contains symbolic - variables with already ended regions. - *) +let apply_symbolic_expansion_to_avalues (config : C.config) + (allow_reborrows : bool) (original_sv : V.symbolic_value) + (expansion : V.typed_value) (ctx : C.eval_ctx) : C.eval_ctx = + (* Symbolic values contained in the expansion might contain already ended regions *) let check_symbolic_no_ended = false in + (* Prepare reborrows registration *) + let fresh_reborrow, apply_registered_reborrows = + prepare_reborrows config allow_reborrows ctx + in (* Visitor to apply the expansion *) let obj = object inherit [_] C.map_eval_ctx as super - method! visit_Symbolic env spc = - if spc.V.svalue = original_sv then expansion.V.value - else super#visit_Symbolic env spc - (** Replace a symbolic value with its expansion. - Note that there may be several references to the same symbolic value - in the context, if the value has been copied. Expansion is then a bit - subtle in the case we expand shared borrows, in which case we need to - introduce a unique borrow identifier for every borrow (this is not - the case here: this function should NOT be used to expand borrows). - *) - method! visit_abs proj_regions abs = assert (Option.is_none proj_regions); let proj_regions = Some abs.V.regions in @@ -2830,7 +2835,40 @@ let apply_symbolic_expansion_non_borrow (config : C.config) end in (* Apply the expansion *) - obj#visit_eval_ctx None ctx + let ctx = obj#visit_eval_ctx None ctx in + (* Apply the reborrows *) + apply_registered_reborrows ctx + +(** Apply a symbolic expansion to a context, by replacing the original + symbolic value with its expanded value. Is valid only if the expansion + is not a borrow (i.e., an adt...). +*) +let apply_symbolic_expansion_non_borrow (config : C.config) + (original_sv : V.symbolic_value) (expansion : V.typed_value) + (ctx : C.eval_ctx) : C.eval_ctx = + (* Visitor to apply the expansion to non-abstraction values *) + let obj = + object + inherit [_] C.map_eval_ctx as super + + method! visit_Symbolic env spc = + if spc.V.svalue = original_sv then expansion.V.value + else super#visit_Symbolic env spc + (** Replace a symbolic value with its expansion. + Note that there may be several references to the same symbolic value + in the context, if the value has been copied. Expansion is then a bit + subtle in the case we expand shared borrows, in which case we need to + introduce a unique borrow identifier for every borrow (this is not + the case here: this function should NOT be used to expand borrows). + *) + end + in + (* Apply the expansion to non-abstraction values *) + let ctx = obj#visit_eval_ctx None ctx in + (* Apply the expansion to abstraction values *) + let allow_reborrows = false in + apply_symbolic_expansion_to_avalues config allow_reborrows original_sv + expansion ctx (** Expand a symbolic value which is not an enumeration with several variants. |