Mark MAP.lookup* rules as preserving-definedness, add in_keys rules #3987
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November 10, 2023 23:54
* The symbolic `Map.lookup` rules preserve definedness by ensuring
that the decomposed map argument is well-defined (no duplicate
keys). If not (i.e., the LHS was undefined), the RHS will include
`ensures #Bottom`.
* Likewise, the symbolic `Map.lookupOrDefault` rules preserve
definedness by ensuring that the decomposed map argument is
well-defined (no duplicate keys). If not (i.e., the LHS was
undefined), the RHS will include `ensures #Bottom`.
* Rules are added to express the `MAP.in_keys` semantics in K instead
of using inline kore as the existing simplification rules did.
- `K in_keys(.Map)` simplifies to `K =/= K` to carry undefined key
arguments over to the RHS
- As in the `lookup` rules, `K in_keys( <decomposed> )` cases use
an `ensures` clause to carry undefined `Map` arguments to the RHS.
Many `in_keys` expressions in the expectations can now be evaluated to `true` or identified as redundant (a more specific condition is present).
jberthold
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Feb 19, 2024
## Stronger `Map` matching Previously, only fully concrete maps (all keys and values identical) would have matched, which is highly unlikely when matching simplification rules. Now we compare the key sets for (syntactic) equality after substituting with the current substitution, and then try to perform matching on the remainder if a solution is at all possible. Most importantly, maps of fully-concrete keys can now be handled, matching the contained values. In addition, the case of matching a single unknown key out of a singleton map (i.e., without opaque rest in the subject map) is now possible. Any ambiguous case is still rejected as `MatchIndeterminate` but some cases can be decided as `MatchFailed` immediately. ## Selected hooks for `Map` This change implements 3 crucial hooks for internalised `Map`s: * `lookup`: partial function that looks up a value for a given key in a map. Returns no result when the key is not present. * `lookupOrDefault`: total function that looks up a value for a given key in a map. If the key is not present, it returns a given default value instead. The implemented hook won't return any result when the presence of the key cannot be decided. * `in_keys`: predicate that checks whether a given key is present in a map. The implemented hook won't return any result if the presence of the key cannot be decided. All three hooks are conservative, not returning any results when they find unevaluated (parts of the) arguments. These hooks, together with the enhanced `Map`-matching of #502, avoid a fall-back to legacy `kore-rpc` in an issue reported in #498. Alternatively, [more suitable rules for `in_keys` could be added to `domains.md`, and the rules for `lookup` and `lookupOrDefault` could be marked as `preserves-definedness`](runtimeverification/k#3987) so `booster` will use them. Fixes #498
|
Obsolete after implementing the relevant hooks. |
jberthold
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Apr 10, 2024
## Stronger `Map` matching Previously, only fully concrete maps (all keys and values identical) would have matched, which is highly unlikely when matching simplification rules. Now we compare the key sets for (syntactic) equality after substituting with the current substitution, and then try to perform matching on the remainder if a solution is at all possible. Most importantly, maps of fully-concrete keys can now be handled, matching the contained values. In addition, the case of matching a single unknown key out of a singleton map (i.e., without opaque rest in the subject map) is now possible. Any ambiguous case is still rejected as `MatchIndeterminate` but some cases can be decided as `MatchFailed` immediately. ## Selected hooks for `Map` This change implements 3 crucial hooks for internalised `Map`s: * `lookup`: partial function that looks up a value for a given key in a map. Returns no result when the key is not present. * `lookupOrDefault`: total function that looks up a value for a given key in a map. If the key is not present, it returns a given default value instead. The implemented hook won't return any result when the presence of the key cannot be decided. * `in_keys`: predicate that checks whether a given key is present in a map. The implemented hook won't return any result if the presence of the key cannot be decided. All three hooks are conservative, not returning any results when they find unevaluated (parts of the) arguments. These hooks, together with the enhanced `Map`-matching of #502, avoid a fall-back to legacy `kore-rpc` in an issue reported in #498. Alternatively, [more suitable rules for `in_keys` could be added to `domains.md`, and the rules for `lookup` and `lookupOrDefault` could be marked as `preserves-definedness`](runtimeverification/k#3987) so `booster` will use them. Fixes #498
jberthold
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Apr 10, 2024
## Stronger `Map` matching Previously, only fully concrete maps (all keys and values identical) would have matched, which is highly unlikely when matching simplification rules. Now we compare the key sets for (syntactic) equality after substituting with the current substitution, and then try to perform matching on the remainder if a solution is at all possible. Most importantly, maps of fully-concrete keys can now be handled, matching the contained values. In addition, the case of matching a single unknown key out of a singleton map (i.e., without opaque rest in the subject map) is now possible. Any ambiguous case is still rejected as `MatchIndeterminate` but some cases can be decided as `MatchFailed` immediately. ## Selected hooks for `Map` This change implements 3 crucial hooks for internalised `Map`s: * `lookup`: partial function that looks up a value for a given key in a map. Returns no result when the key is not present. * `lookupOrDefault`: total function that looks up a value for a given key in a map. If the key is not present, it returns a given default value instead. The implemented hook won't return any result when the presence of the key cannot be decided. * `in_keys`: predicate that checks whether a given key is present in a map. The implemented hook won't return any result if the presence of the key cannot be decided. All three hooks are conservative, not returning any results when they find unevaluated (parts of the) arguments. These hooks, together with the enhanced `Map`-matching of #502, avoid a fall-back to legacy `kore-rpc` in an issue reported in #498. Alternatively, [more suitable rules for `in_keys` could be added to `domains.md`, and the rules for `lookup` and `lookupOrDefault` could be marked as `preserves-definedness`](runtimeverification/k#3987) so `booster` will use them. Fixes #498
jberthold
added a commit
to runtimeverification/haskell-backend
that referenced
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Apr 10, 2024
## Stronger `Map` matching Previously, only fully concrete maps (all keys and values identical) would have matched, which is highly unlikely when matching simplification rules. Now we compare the key sets for (syntactic) equality after substituting with the current substitution, and then try to perform matching on the remainder if a solution is at all possible. Most importantly, maps of fully-concrete keys can now be handled, matching the contained values. In addition, the case of matching a single unknown key out of a singleton map (i.e., without opaque rest in the subject map) is now possible. Any ambiguous case is still rejected as `MatchIndeterminate` but some cases can be decided as `MatchFailed` immediately. ## Selected hooks for `Map` This change implements 3 crucial hooks for internalised `Map`s: * `lookup`: partial function that looks up a value for a given key in a map. Returns no result when the key is not present. * `lookupOrDefault`: total function that looks up a value for a given key in a map. If the key is not present, it returns a given default value instead. The implemented hook won't return any result when the presence of the key cannot be decided. * `in_keys`: predicate that checks whether a given key is present in a map. The implemented hook won't return any result if the presence of the key cannot be decided. All three hooks are conservative, not returning any results when they find unevaluated (parts of the) arguments. These hooks, together with the enhanced `Map`-matching of #502, avoid a fall-back to legacy `kore-rpc` in an issue reported in #498. Alternatively, [more suitable rules for `in_keys` could be added to `domains.md`, and the rules for `lookup` and `lookupOrDefault` could be marked as `preserves-definedness`](runtimeverification/k#3987) so `booster` will use them. Fixes #498
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Map.lookuprules preserve definedness by ensuring that the decomposed map argument is well-defined (no duplicate keys). If not (i.e., the LHS was undefined), the RHS will includeensures #Bottom.Map.lookupOrDefaultrules preserve definedness by ensuring that the decomposed map argument is well-defined (no duplicate keys). If not (i.e., the LHS was undefined), the RHS will includeensures #Bottom.MAP.in_keyssemantics in K instead of using inline kore as the existing simplification rules did.K in_keys(.Map)simplifies toK =/= Kto carry undefined key arguments over to the RHSlookuprules,K in_keys( <decomposed> )cases use anensuresclause to carry undefinedMaparguments to the RHS.This PR addresses an issue reported in runtimeverification/hs-backend-booster#498 Alternatively, this can be addressed by implementing hooks in booster for the
MAP.lookup*andMAP.in_keysfunctions (see runtimeverification/hs-backend-booster#506)