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feat(BV): Interval domains for bit-vectors #1058
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Note: this is +107-515 or a net regression of about 400 problems on our QF_BV subset. This is expected: this PR uses bit-vector domains for A follow-up PR (should be ready sometime next week) fixes that by implementing arithmetic propagators for the BV interval domains: it is currently +1156-209 (or an improvement of almost 1000 problems) on that same subset compared to |
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After reading and thinking a lot (and starting a small Coq developement) about the explanations for intervals:
That is not to say that I don't think they are correct (in particular, I am confident that all of these functions return the right values for the bounds), but that they may forget necessary explanations in some cases, causing unsoundness. I think the cases where we forget explanations are quite rare (or may be made impossible currently) so I will rewrite these functions to try to be less clever and add more explanations. I will also write a documentation for the intervals module, now that i understand the invariants better. This does not impact the rest of the PR or the rest of the PRs in the stack. |
Turns out they are not (: I thought I had replicated the behavior of the |
I started a review of the code? Should I discard it? |
Everything except for changes to the |
Honestly, when I read this module months ago, my conclusion was we should rewrite it completely. It's not a priority but I plan to work on it later. |
I am about 99% sure there currently are soundness bugs that can be triggered by properly crafted formulas so I am actually looking into it now. Hopefully I will not need a full rewrite to fix them :/ |
The existing Intervals module suffers from multiple drawbacks. It is undocumented, uses a questionable implementation where explanations associated with each internal bounds have unclear semantics (did I mention it is not documented), and it has been the source of many soundness bug in the past due to the way it uses exceptions to indicate emptiness. This makes it hard to extend the module; for instance OCamlPro#1058 was delayed because we were not quite sure whether the implementation of functions related to bit-vectors were correct. This patch is a reimplementation of the Intervals module from scratch. The new implementation keeps the representation used by the `intersect` function in the existing implementation (and in a way can be thought of as resolving the TODO in the existing implementation suggesting to generalize that type). It is thoroughly documented, and is split between a "core" module that provides safe functions to deal with explanations, and specialized implementations for common functions (addition, multiplication, etc.) using the "core" interface such that reasoning about the implementation of addition etc. does not require thinking about explanations at all. This makes it easier to extend the module with new specialized functions. The implementation is done through a (small) family of functors, allowing separate implementations for real and integer intervals that prevent accidentally mixing them up. For the time being, the old interface is re-implemented on top of the new interface (except where implementation details leaked too much) so as to keep the changes mostly confined to the `Intervals` module. Migrating to the new interface (and especially abandoning the use of exceptions) will be done in a second step. The patch is relatively big, but can't realistically be split into smaller parts without ending up in intermediate states full of dead code. I suggest reviewers first take a look at the documentation of the `OrderedType`, `Interval` and `Union` signatures in the `Intervals_intf` module (note that this includes some LaTeX, and might be easier to read using `odoc` -- I tried to make sure the `odoc`-generated documentation was usable). This should provide a good understanding of the "core" functionality of the new implementation. The rest of the review can be split into parts that should be mostly independent: - Implementation of the `OrderedType` interface for `Z.t` and `Q.t` in `ZEuclideanType` and `QAlgebraicType`; - Implementation of the concrete functions for addition, multiplication, etc. in the `Intervals` module; - Re-implementation of the old API in the `Intervals.Legacy` module (and minor related changes in other modules, notably `IntervalCalculus`); - Implementation of the "core" functionality in the `Intervals_core` module.
The existing Intervals module suffers from multiple drawbacks. It is undocumented, uses a questionable implementation where explanations associated with each internal bounds have unclear semantics (did I mention it is not documented), and it has been the source of many soundness bug in the past due to the way it uses exceptions to indicate emptiness. This makes it hard to extend the module; for instance OCamlPro#1058 was delayed because we were not quite sure whether the implementation of functions related to bit-vectors were correct. This patch is a reimplementation of the Intervals module from scratch. The new implementation keeps the representation used by the `intersect` futnction in the existing implementation (and in a way can be thought of as resolving the TODO in the existing implementation suggesting to generalize that type). It is thoroughly documented, and is split between a "core" module that provides safe functions to deal with explanations, and specialized implementations for common functions (addition, multiplication, etc.) using the "core" interface such that reasoning about the implementation of addition etc. does not require thinking about explanations at all. This makes it easier to extend the module with new specialized functions. The implementation is done through a (small) family of functors, allowing separate implementations for real and integer intervals that prevent accidentally mixing them up. For the time being, the old interface is re-implemented on top of the new interface (except where implementation details leaked too much) so as to keep the changes mostly confined to the `Intervals` module. Migrating to the new interface (and especially abandoning the use of exceptions) will be done in a second step. The patch is relatively big, but can't realistically be split into smaller parts without ending up in intermediate states full of dead code. I suggest reviewers first take a look at the documentation of the `OrderedType`, `Interval` and `Union` signatures in the `Intervals_intf` module (note that this includes some LaTeX, and might be easier to read using `odoc` -- I tried to make sure the `odoc`-generated documentation was usable). This should provide a good understanding of the "core" functionality of the new implementation. The rest of the review can be split into parts that should be mostly independent: - Implementation of the `OrderedType` interface for `Z.t` and `Q.t` in `ZEuclideanType` and `QAlgebraicType`; - Implementation of the concrete functions for addition, multiplication, etc. in the `Intervals` module; - Re-implementation of the old API in the `Intervals.Legacy` module (and minor related changes in other modules, notably `IntervalCalculus`); - Implementation of the "core" functionality in the `Intervals_core` module.
I have adapted the code on top of #1108 (unfortunately I messed up the rebase so the history is a bit weird, apologies for that!). |
FWIW: We were in the 1% of chances, but the code in this PR for |
The existing Intervals module suffers from multiple drawbacks. It is undocumented, uses a questionable implementation where explanations associated with each internal bounds have unclear semantics (did I mention it is not documented), and it has been the source of many soundness bug in the past due to the way it uses exceptions to indicate emptiness. This makes it hard to extend the module; for instance OCamlPro#1058 was delayed because we were not quite sure whether the implementation of functions related to bit-vectors were correct. This patch is a reimplementation of the Intervals module from scratch. The new implementation keeps the representation used by the `intersect` futnction in the existing implementation (and in a way can be thought of as resolving the TODO in the existing implementation suggesting to generalize that type). It is thoroughly documented, and is split between a "core" module that provides safe functions to deal with explanations, and specialized implementations for common functions (addition, multiplication, etc.) using the "core" interface such that reasoning about the implementation of addition etc. does not require thinking about explanations at all. This makes it easier to extend the module with new specialized functions. The implementation is done through a (small) family of functors, allowing separate implementations for real and integer intervals that prevent accidentally mixing them up. For the time being, the old interface is re-implemented on top of the new interface (except where implementation details leaked too much) so as to keep the changes mostly confined to the `Intervals` module. Migrating to the new interface (and especially abandoning the use of exceptions) will be done in a second step. The patch is relatively big, but can't realistically be split into smaller parts without ending up in intermediate states full of dead code. I suggest reviewers first take a look at the documentation of the `OrderedType`, `Interval` and `Union` signatures in the `Intervals_intf` module (note that this includes some LaTeX, and might be easier to read using `odoc` -- I tried to make sure the `odoc`-generated documentation was usable). This should provide a good understanding of the "core" functionality of the new implementation. The rest of the review can be split into parts that should be mostly independent: - Implementation of the `OrderedType` interface for `Z.t` and `Q.t` in `ZEuclideanType` and `QAlgebraicType`; - Implementation of the concrete functions for addition, multiplication, etc. in the `Intervals` module; - Re-implementation of the old API in the `Intervals.Legacy` module (and minor related changes in other modules, notably `IntervalCalculus`); - Implementation of the "core" functionality in the `Intervals_core` module.
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The existing Intervals module suffers from multiple drawbacks. It is undocumented, uses a questionable implementation where explanations associated with each internal bounds have unclear semantics (did I mention it is not documented), and it has been the source of many soundness bug in the past due to the way it uses exceptions to indicate emptiness. This makes it hard to extend the module; for instance OCamlPro#1058 was delayed because we were not quite sure whether the implementation of functions related to bit-vectors were correct. This patch is a reimplementation of the Intervals module from scratch. The new implementation keeps the representation used by the `intersect` futnction in the existing implementation (and in a way can be thought of as resolving the TODO in the existing implementation suggesting to generalize that type). It is thoroughly documented, and is split between a "core" module that provides safe functions to deal with explanations, and specialized implementations for common functions (addition, multiplication, etc.) using the "core" interface such that reasoning about the implementation of addition etc. does not require thinking about explanations at all. This makes it easier to extend the module with new specialized functions. The implementation is done through a (small) family of functors, allowing separate implementations for real and integer intervals that prevent accidentally mixing them up. For the time being, the old interface is re-implemented on top of the new interface (except where implementation details leaked too much) so as to keep the changes mostly confined to the `Intervals` module. Migrating to the new interface (and especially abandoning the use of exceptions) will be done in a second step. The patch is relatively big, but can't realistically be split into smaller parts without ending up in intermediate states full of dead code. I suggest reviewers first take a look at the documentation of the `OrderedType`, `Interval` and `Union` signatures in the `Intervals_intf` module (note that this includes some LaTeX, and might be easier to read using `odoc` -- I tried to make sure the `odoc`-generated documentation was usable). This should provide a good understanding of the "core" functionality of the new implementation. The rest of the review can be split into parts that should be mostly independent: - Implementation of the `OrderedType` interface for `Z.t` and `Q.t` in `ZEuclideanType` and `QAlgebraicType`; - Implementation of the concrete functions for addition, multiplication, etc. in the `Intervals` module; - Re-implementation of the old API in the `Intervals.Legacy` module (and minor related changes in other modules, notably `IntervalCalculus`); - Implementation of the "core" functionality in the `Intervals_core` module.
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The existing Intervals module suffers from multiple drawbacks. It is undocumented, uses a questionable implementation where explanations associated with each internal bounds have unclear semantics (did I mention it is not documented), and it has been the source of many soundness bug in the past due to the way it uses exceptions to indicate emptiness. This makes it hard to extend the module; for instance OCamlPro#1058 was delayed because we were not quite sure whether the implementation of functions related to bit-vectors were correct. This patch is a reimplementation of the Intervals module from scratch. The new implementation keeps the representation used by the `intersect` futnction in the existing implementation (and in a way can be thought of as resolving the TODO in the existing implementation suggesting to generalize that type). It is thoroughly documented, and is split between a "core" module that provides safe functions to deal with explanations, and specialized implementations for common functions (addition, multiplication, etc.) using the "core" interface such that reasoning about the implementation of addition etc. does not require thinking about explanations at all. This makes it easier to extend the module with new specialized functions. The implementation is done through a (small) family of functors, allowing separate implementations for real and integer intervals that prevent accidentally mixing them up. For the time being, the old interface is re-implemented on top of the new interface (except where implementation details leaked too much) so as to keep the changes mostly confined to the `Intervals` module. Migrating to the new interface (and especially abandoning the use of exceptions) will be done in a second step. The patch is relatively big, but can't realistically be split into smaller parts without ending up in intermediate states full of dead code. I suggest reviewers first take a look at the documentation of the `OrderedType`, `Interval` and `Union` signatures in the `Intervals_intf` module (note that this includes some LaTeX, and might be easier to read using `odoc` -- I tried to make sure the `odoc`-generated documentation was usable). This should provide a good understanding of the "core" functionality of the new implementation. The rest of the review can be split into parts that should be mostly independent: - Implementation of the `OrderedType` interface for `Z.t` and `Q.t` in `ZEuclideanType` and `QAlgebraicType`; - Implementation of the concrete functions for addition, multiplication, etc. in the `Intervals` module; - Re-implementation of the old API in the `Intervals.Legacy` module (and minor related changes in other modules, notably `IntervalCalculus`); - Implementation of the "core" functionality in the `Intervals_core` module.
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The existing Intervals module suffers from multiple drawbacks. It is undocumented, uses a questionable implementation where explanations associated with each internal bounds have unclear semantics (did I mention it is not documented), and it has been the source of many soundness bug in the past due to the way it uses exceptions to indicate emptiness. This makes it hard to extend the module; for instance OCamlPro#1058 was delayed because we were not quite sure whether the implementation of functions related to bit-vectors were correct. This patch is a reimplementation of the Intervals module from scratch. The new implementation keeps the representation used by the `intersect` futnction in the existing implementation (and in a way can be thought of as resolving the TODO in the existing implementation suggesting to generalize that type). It is thoroughly documented, and is split between a "core" module that provides safe functions to deal with explanations, and specialized implementations for common functions (addition, multiplication, etc.) using the "core" interface such that reasoning about the implementation of addition etc. does not require thinking about explanations at all. This makes it easier to extend the module with new specialized functions. The implementation is done through a (small) family of functors, allowing separate implementations for real and integer intervals that prevent accidentally mixing them up. For the time being, the old interface is re-implemented on top of the new interface (except where implementation details leaked too much) so as to keep the changes mostly confined to the `Intervals` module. Migrating to the new interface (and especially abandoning the use of exceptions) will be done in a second step. The patch is relatively big, but can't realistically be split into smaller parts without ending up in intermediate states full of dead code. I suggest reviewers first take a look at the documentation of the `OrderedType`, `Interval` and `Union` signatures in the `Intervals_intf` module (note that this includes some LaTeX, and might be easier to read using `odoc` -- I tried to make sure the `odoc`-generated documentation was usable). This should provide a good understanding of the "core" functionality of the new implementation. The rest of the review can be split into parts that should be mostly independent: - Implementation of the `OrderedType` interface for `Z.t` and `Q.t` in `ZEuclideanType` and `QAlgebraicType`; - Implementation of the concrete functions for addition, multiplication, etc. in the `Intervals` module; - Re-implementation of the old API in the `Intervals.Legacy` module (and minor related changes in other modules, notably `IntervalCalculus`); - Implementation of the "core" functionality in the `Intervals_core` module.
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* feat: Rewrite the Intervals module entirely The existing Intervals module suffers from multiple drawbacks. It is undocumented, uses a questionable implementation where explanations associated with each internal bounds have unclear semantics (did I mention it is not documented), and it has been the source of many soundness bug in the past due to the way it uses exceptions to indicate emptiness. This makes it hard to extend the module; for instance #1058 was delayed because we were not quite sure whether the implementation of functions related to bit-vectors were correct. This patch is a reimplementation of the Intervals module from scratch. The new implementation keeps the representation used by the `intersect` futnction in the existing implementation (and in a way can be thought of as resolving the TODO in the existing implementation suggesting to generalize that type). It is thoroughly documented, and is split between a "core" module that provides safe functions to deal with explanations, and specialized implementations for common functions (addition, multiplication, etc.) using the "core" interface such that reasoning about the implementation of addition etc. does not require thinking about explanations at all. This makes it easier to extend the module with new specialized functions. The implementation is done through a (small) family of functors, allowing separate implementations for real and integer intervals that prevent accidentally mixing them up. For the time being, the old interface is re-implemented on top of the new interface (except where implementation details leaked too much) so as to keep the changes mostly confined to the `Intervals` module. Migrating to the new interface (and especially abandoning the use of exceptions) will be done in a second step. The patch is relatively big, but can't realistically be split into smaller parts without ending up in intermediate states full of dead code. I suggest reviewers first take a look at the documentation of the `OrderedType`, `Interval` and `Union` signatures in the `Intervals_intf` module (note that this includes some LaTeX, and might be easier to read using `odoc` -- I tried to make sure the `odoc`-generated documentation was usable). This should provide a good understanding of the "core" functionality of the new implementation. The rest of the review can be split into parts that should be mostly independent: - Implementation of the `OrderedType` interface for `Z.t` and `Q.t` in `ZEuclideanType` and `QAlgebraicType`; - Implementation of the concrete functions for addition, multiplication, etc. in the `Intervals` module; - Re-implementation of the old API in the `Intervals.Legacy` module (and minor related changes in other modules, notably `IntervalCalculus`); - Implementation of the "core" functionality in the `Intervals_core` module.
As soon as you rebase it, I will do a last pass on this PR but I think it's already good. |
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Rebased the whole stack. |
src/lib/reasoners/rel_utils.ml
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(** [map_leaves f r acc] is the "inverse" of [fold_leaves] in the sense that | ||
it rebuilds a domain for [r] by using [f] to access the domain for each | ||
of [r]'s leaves. *) |
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This documentation is outdated.
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Done (took me a minute to realize you meant the acc
argument no longer exists).
@@ -30,6 +30,8 @@ | |||
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open Intervals_intf | |||
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val map_bound : ('a -> 'b) -> 'a bound -> 'b bound |
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Please add a documentation :)
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Done.
src/lib/reasoners/intervals_intf.ml
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(** [scale v u] evaluates to {m \{ v \times x \mid x \in S \}} when [u] | ||
evaluates to {m S}. *) |
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This function raises an assertion if the scalar is zero. We should mention it in its documentation.
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Done.
(** [extract s i j] returns the bits of [s] from position [i] to [j], | ||
inclusive. | ||
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Represents the function [fun x -> floor(x / 2^i) % 2^(j - i + 1)]. |
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As this function is clear not semialgebraic, we cannot expect that the image of union of intervals is again an union of intervals. We should mention that this map compute an estimation of this image by an union of intervals.
Do you know if we compute the best approximation, that is the smallest union that contains the image?
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I am not sure I understand your point about semialgebraicity. The image of an (integer) interval by this function is an union of (integer) intervals (in fact either a single interval or an union of two disjoint intervals), so the image of an union of intervals is also an union of intervals.
@@ -75,6 +75,93 @@ let is_bv_ty = function | |||
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let is_bv_r r = is_bv_ty @@ X.type_info r | |||
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module Interval_domain : Rel_utils.Domain with type t = Intervals.Int.t = struct |
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For sake of uniformity, we should rename Domains
into Bitlist_domains
.
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I wanted this patch to avoid touching the bitlist part as much as possible. Renamed it.
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(* Now the interval domain is stable, but the new intervals may have an | ||
impact on the bitlist domains, so we must shrink them again when | ||
applicable. We repeat until a fixpoint is reached. *) | ||
let bcs = Constraints.clear_pending bcs in |
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As we flush the pending constraints here, we can use the new propagate
function in this loop again.
src/lib/reasoners/bitv_rel.ml
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touch_pending queue; | ||
HX.iter (fun r () -> | ||
HX.replace bitlist_changed r (); | ||
constrain_interval_from_bitlist | ||
Interval_domains.Ephemeral.(handle idom r) | ||
Domains.Ephemeral.(!!(handle bdom r)) | ||
) touched; | ||
HX.clear touched; | ||
propagate_intervals queue touched bcs idom; | ||
assert (QC.is_empty queue); |
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Same here.
@Halbaroth as discussed prior to my vacation this is ready for a second pass. |
This patch adds interval domains to the Bitv_rel module, as well as interreductions between the bitlist and interval domains following: Sharpening Constraint Programming approaches for Bit-Vector Theory. Zakaria Chihani, Bruno Marre, François Bobot, Sébastien Bardin. CPAIOR 2017. International Conference on AI and OR Techniques in Constraint Programming for Combinatorial Optimization Problems, Jun 2017, Padova, Italy. More precisely: - The `Intervals` module is extended to support the `extract` operation, which is used to propagate between bit-vector compositions and their components; - The interreductions are implemented using the new `Bitlist.increase_lower_bound`, `Bitlist.decrease_upper_bound`, and the new `shared_msb` helper in `Bitv_rel`; - Propagations are performed by alternating propagations until fixpoint in each domain, followed by interreductions and propagations until fixpoint in the other domain, until reaching a fixpoint for the whole procedure. It is not clear that this is the best strategy; the goal is to try and limit interreductions since they are relatively expensive but we should revisit this once more operations are supported. For now, only the `bvule`, `bvult`, `bvugt` and `bvuge` primitives are supported as built-in bit-vector operations; other operations such as `bvadd` are still encoded using `bv2nat`. These operations will be migrated to bit-vector primitives in a follow-up PR. Finally, there are some tests for the tricky bits (`Intervals.extract` and the interreduction primitives) using QCheck.
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Let's merge this one :)
* feat(BV): Interval domains for bit-vectors This patch adds interval domains to the Bitv_rel module, as well as interreductions between the bitlist and interval domains following: Sharpening Constraint Programming approaches for Bit-Vector Theory. Zakaria Chihani, Bruno Marre, François Bobot, Sébastien Bardin. CPAIOR 2017. International Conference on AI and OR Techniques in Constraint Programming for Combinatorial Optimization Problems, Jun 2017, Padova, Italy. More precisely: - The `Intervals` module is extended to support the `extract` operation, which is used to propagate between bit-vector compositions and their components; - The interreductions are implemented using the new `Bitlist.increase_lower_bound`, `Bitlist.decrease_upper_bound`, and the new `shared_msb` helper in `Bitv_rel`; - Propagations are performed by alternating propagations until fixpoint in each domain, followed by interreductions and propagations until fixpoint in the other domain, until reaching a fixpoint for the whole procedure. It is not clear that this is the best strategy; the goal is to try and limit interreductions since they are relatively expensive but we should revisit this once more operations are supported. For now, only the `bvule`, `bvult`, `bvugt` and `bvuge` primitives are supported as built-in bit-vector operations; other operations such as `bvadd` are still encoded using `bv2nat`. These operations will be migrated to bit-vector primitives in a follow-up PR. Finally, there are some tests for the tricky bits (`Intervals.extract` and the interreduction primitives) using QCheck.
CHANGES: ### Command-line interface - Enable FPA theory by default (OCamlPro/alt-ergo#1177) - Remove deprecated output channels (OCamlPro/alt-ergo#782) - Deprecate the --use-underscore since it produces models that are not SMT-LIB compliant (OCamlPro/alt-ergo#805) - Add --dump-models-on to dump models on a specific output channel (OCamlPro/alt-ergo#838) - Use consistent return codes (OCamlPro/alt-ergo#842) - Add --continue-on-error flag to set the SMT-LIB error behavior (OCamlPro/alt-ergo#853) - Make dolmen the default value for the --frontend option (OCamlPro/alt-ergo#857) - Restore functionality to broken `--profiling` option (OCamlPro/alt-ergo#947) - Add bare-bones support for interactive input in SMT-LIB format (OCamlPro/alt-ergo#949) - Less confusing behavior on timeout (OCamlPro/alt-ergo#982, OCamlPro/alt-ergo#984) - Add `--strict` option for SMT-LIB compliant mode (OCamlPro/alt-ergo#916, OCamlPro/alt-ergo#1133) - Deprecate `sum`, `typing` and `warnings` debug flags (OCamlPro/alt-ergo#1204) ### SMT-LIB support - Add support for the many new SMT-LIB commands (OCamlPro/alt-ergo#837, OCamlPro/alt-ergo#848, OCamlPro/alt-ergo#852, OCamlPro/alt-ergo#863, OCamlPro/alt-ergo#911, OCamlPro/alt-ergo#942, OCamlPro/alt-ergo#945, OCamlPro/alt-ergo#961, OCamlPro/alt-ergo#975, OCamlPro/alt-ergo#1069) - Expose the FPA rounding builtin in the SMT-LIB format (OCamlPro/alt-ergo#876, OCamlPro/alt-ergo#1135) - Allow changing the SAT solver using (set-option) (OCamlPro/alt-ergo#880) - Add support for the `:named` attribute (OCamlPro/alt-ergo#957) - Add support for quoted identifiers (OCamlPro/alt-ergo#909, OCamlPro/alt-ergo#972) - Add support for naming lemmas in SMT-LIB syntax (OCamlPro/alt-ergo#1141, OCamlPro/alt-ergo#1143) ### Model generation - Use post-solve SAT environment in model generation, fixing issues where incorrect models were generated (OCamlPro/alt-ergo#789) - Restore support for records in models (OCamlPro/alt-ergo#793) - Use abstract values instead of dummy values in models where the actual value does not matter (OCamlPro/alt-ergo#804, OCamlPro/alt-ergo#835) - Use fresh names for all abstract values to prevent accidental captures (OCamlPro/alt-ergo#811) - Add support for model generation with the default CDCL solver (OCamlPro/alt-ergo#829) - Support model generation for the BV theory (OCamlPro/alt-ergo#841, OCamlPro/alt-ergo#968) - Add support for optimization (MaxSMT / OptiSMT) with lexicographic Int and Real objectives (OCamlPro/alt-ergo#861, OCamlPro/alt-ergo#921) - Add a SMT-LIB printer for expressions (OCamlPro/alt-ergo#952, OCamlPro/alt-ergo#981, OCamlPro/alt-ergo#1082, OCamlPro/alt-ergo#931, OCamlPro/alt-ergo#932) - Ensure models have a value for all constants in the problem (OCamlPro/alt-ergo#1019) - Fix a rare soundness issue with integer constraints when model generation is enabled (OCamlPro/alt-ergo#1025) - Support model generation for the ADT theory (OCamlPro/alt-ergo#1093, OCamlPro/alt-ergo#1153) ### Theory reasoning - Add word-level propagators for the BV theory (OCamlPro/alt-ergo#944, OCamlPro/alt-ergo#1004, OCamlPro/alt-ergo#1007, OCamlPro/alt-ergo#1010, OCamlPro/alt-ergo#1011, OCamlPro/alt-ergo#1012, OCamlPro/alt-ergo#1040, OCamlPro/alt-ergo#1044, OCamlPro/alt-ergo#1054, OCamlPro/alt-ergo#1055, OCamlPro/alt-ergo#1056, OCamlPro/alt-ergo#1057, OCamlPro/alt-ergo#1065, OCamlPro/alt-ergo#1073, OCamlPro/alt-ergo#1144, OCamlPro/alt-ergo#1152) - Add interval domains and arithmetic propagators for the BV theory (OCamlPro/alt-ergo#1058, OCamlPro/alt-ergo#1083, OCamlPro/alt-ergo#1084, OCamlPro/alt-ergo#1085) - Native support for bv2nat of bit-vector normal forms (OCamlPro/alt-ergo#1154) - Fix incompleteness issues in the BV solver (OCamlPro/alt-ergo#978, OCamlPro/alt-ergo#979) - Abstract more arguments of AC symbols to avoid infinite loops when they contain other AC symbols (OCamlPro/alt-ergo#990) - Do not make irrelevant decisions in CDCL solver, improving performance slightly (OCamlPro/alt-ergo#1041) - Rewrite the ADT theory to use domains and integrate the enum theory into the ADT theory (OCamlPro/alt-ergo#1078, OCamlPro/alt-ergo#1086, OCamlPro/alt-ergo#1087, OCamlPro/alt-ergo#1091, OCamlPro/alt-ergo#1094, OCamlPro/alt-ergo#1138) - Rewrite the Intervals module entirely (OCamlPro/alt-ergo#1108) - Add maximize/minimize terms for matching (OCamlPro/alt-ergo#1166) - Internalize `sign_extend` and `repeat` (OCamlPro/alt-ergo#1192) - Run cross-propagators to completion (OCamlPro/alt-ergo#1221) - Support binary distinct on arbitrary bit-widths (OCamlPro/alt-ergo#1222) - Only perform optimization when building a model (OCamlPro/alt-ergo#1224) - Make sure domains do not overflow the default domain (OCamlPro/alt-ergo#1225) - Do not build unnormalized values in `zero_extend` (OCamlPro/alt-ergo#1226) ### Internal/library changes - Rewrite the Vec module (OCamlPro/alt-ergo#607) - Move printer definitions closer to type definitions (OCamlPro/alt-ergo#808) - Mark proxy names as reserved (OCamlPro/alt-ergo#836) - Use a Zarith-based representation for numbers and bit-vectors (OCamlPro/alt-ergo#850, OCamlPro/alt-ergo#943) - Add native support for (bvnot) in the BV solver (OCamlPro/alt-ergo#856) - Add constant propagators for partially interpreted functions (OCamlPro/alt-ergo#869) - Remove `Util.failwith` in favor of `Fmt.failwith` (OCamlPro/alt-ergo#872) - Add more `Expr` smart constructors (OCamlPro/alt-ergo#877, OCamlPro/alt-ergo#878) - Do not use existential variables for integer division (OCamlPro/alt-ergo#881) - Preserve `Subst` literals to prevent accidental incompleteness (OCamlPro/alt-ergo#886) - Properly start timers (OCamlPro/alt-ergo#924) - Compute a concrete representation of a model instead of performing (OCamlPro/alt-ergo#925) - Allow direct access to the SAT API in the Alt-Ergo library computations during printing (OCamlPro/alt-ergo#927) - Better handling for step limit (OCamlPro/alt-ergo#936) - Add a generic option manager to deal with the dolmen state (OCamlPro/alt-ergo#951) - Expose an imperative SAT API in the Alt-Ergo library (OCamlPro/alt-ergo#962) - Keep track of the SMT-LIB mode (OCamlPro/alt-ergo#971) - Add ability to decide on semantic literals (OCamlPro/alt-ergo#1027, OCamlPro/alt-ergo#1118) - Preserve trigger order when parsing quantifiers with multiple trigger (OCamlPro/alt-ergo#1046). - Store domains inside the union-find module (OCamlPro/alt-ergo#1119) - Remove some polymorphic hashtables (OCamlPro/alt-ergo#1219) ### Build and integration - Drop support for OCaml <4.08.1 (OCamlPro/alt-ergo#803) - Use dune-site for the inequalities plugins. External pluginsm ust now be registered through the dune-site plugin mechanism in the `(alt-ergo plugins)` site to be picked up by Alt-Ergo (OCamlPro/alt-ergo#1049). - Add a release workflow (OCamlPro/alt-ergo#827) - Add a Windows workflow (OCamlPro/alt-ergo#1203) - Mark the dune.inc file as linguist-generated to avoid huge diffs (OCamlPro/alt-ergo#830) - Use GitHub Actions badges in the README (OCamlPro/alt-ergo#882) - Use `dune build @check` to build the project (OCamlPro/alt-ergo#887) - Enable warnings as errors on the CI (OCamlPro/alt-ergo#888) - Uniformization of internal identifiers generation (OCamlPro/alt-ergo#905, OCamlPro/alt-ergo#918) - Use an efficient `String.starts_with` implementation (OCamlPro/alt-ergo#912) - Fix the Makefile (OCamlPro/alt-ergo#914) - Add `Logs` dependency (OCamlPro/alt-ergo#1206) - Use `dynamic_include` to include the generated file `dune.inc` (OCamlPro/alt-ergo#1199) - Support Windows (OCamlPro/alt-ergo#1184,OCamlPro/alt-ergo#1189,OCamlPro/alt-ergo#1195,OCamlPro/alt-ergo#1199,OCamlPro/alt-ergo#1200) - Wrap the library `Alt_ergo_prelude` (OCamlPro/alt-ergo#1223) ### Testing - Use --enable-assertions in tests (OCamlPro/alt-ergo#809) - Add a test for push/pop (OCamlPro/alt-ergo#843) - Use the CDCL solver when testing model generation (OCamlPro/alt-ergo#938) - Do not test .smt2 files with the legacy frontend (OCamlPro/alt-ergo#939) - Restore automatic creation of .expected files (OCamlPro/alt-ergo#941) ### Documentation - Add a new example for model generation (OCamlPro/alt-ergo#826) - Add a Pygments lexer for the Alt-Ergo native language (OCamlPro/alt-ergo#862) - Update the current authors (OCamlPro/alt-ergo#865) - Documentation of the `Enum` theory (OCamlPro/alt-ergo#871) - Document `Th_util.lit_origin` (OCamlPro/alt-ergo#915) - Document the CDCL-Tableaux solver (OCamlPro/alt-ergo#995) - Document Windows support (OCamlPro/alt-ergo#1216) - Remove instructions to install Alt-Ergo on Debian (OCamlPro/alt-ergo#1217) - Document optimization feature (OCamlPro/alt-ergo#1231)
CHANGES: ### Command-line interface - Enable FPA theory by default (OCamlPro/alt-ergo#1177) - Remove deprecated output channels (OCamlPro/alt-ergo#782) - Deprecate the --use-underscore since it produces models that are not SMT-LIB compliant (OCamlPro/alt-ergo#805) - Add --dump-models-on to dump models on a specific output channel (OCamlPro/alt-ergo#838) - Use consistent return codes (OCamlPro/alt-ergo#842) - Add --continue-on-error flag to set the SMT-LIB error behavior (OCamlPro/alt-ergo#853) - Make dolmen the default value for the --frontend option (OCamlPro/alt-ergo#857) - Restore functionality to broken `--profiling` option (OCamlPro/alt-ergo#947) - Add bare-bones support for interactive input in SMT-LIB format (OCamlPro/alt-ergo#949) - Less confusing behavior on timeout (OCamlPro/alt-ergo#982, OCamlPro/alt-ergo#984) - Add `--strict` option for SMT-LIB compliant mode (OCamlPro/alt-ergo#916, OCamlPro/alt-ergo#1133) - Deprecate `sum`, `typing` and `warnings` debug flags (OCamlPro/alt-ergo#1204) ### SMT-LIB support - Add support for the many new SMT-LIB commands (OCamlPro/alt-ergo#837, OCamlPro/alt-ergo#848, OCamlPro/alt-ergo#852, OCamlPro/alt-ergo#863, OCamlPro/alt-ergo#911, OCamlPro/alt-ergo#942, OCamlPro/alt-ergo#945, OCamlPro/alt-ergo#961, OCamlPro/alt-ergo#975, OCamlPro/alt-ergo#1069) - Expose the FPA rounding builtin in the SMT-LIB format (OCamlPro/alt-ergo#876, OCamlPro/alt-ergo#1135) - Allow changing the SAT solver using (set-option) (OCamlPro/alt-ergo#880) - Add support for the `:named` attribute (OCamlPro/alt-ergo#957) - Add support for quoted identifiers (OCamlPro/alt-ergo#909, OCamlPro/alt-ergo#972) - Add support for naming lemmas in SMT-LIB syntax (OCamlPro/alt-ergo#1141, OCamlPro/alt-ergo#1143) ### Model generation - Use post-solve SAT environment in model generation, fixing issues where incorrect models were generated (OCamlPro/alt-ergo#789) - Restore support for records in models (OCamlPro/alt-ergo#793) - Use abstract values instead of dummy values in models where the actual value does not matter (OCamlPro/alt-ergo#804, OCamlPro/alt-ergo#835) - Use fresh names for all abstract values to prevent accidental captures (OCamlPro/alt-ergo#811) - Add support for model generation with the default CDCL solver (OCamlPro/alt-ergo#829) - Support model generation for the BV theory (OCamlPro/alt-ergo#841, OCamlPro/alt-ergo#968) - Add support for optimization (MaxSMT / OptiSMT) with lexicographic Int and Real objectives (OCamlPro/alt-ergo#861, OCamlPro/alt-ergo#921) - Add a SMT-LIB printer for expressions (OCamlPro/alt-ergo#952, OCamlPro/alt-ergo#981, OCamlPro/alt-ergo#1082, OCamlPro/alt-ergo#931, OCamlPro/alt-ergo#932) - Ensure models have a value for all constants in the problem (OCamlPro/alt-ergo#1019) - Fix a rare soundness issue with integer constraints when model generation is enabled (OCamlPro/alt-ergo#1025) - Support model generation for the ADT theory (OCamlPro/alt-ergo#1093, OCamlPro/alt-ergo#1153) ### Theory reasoning - Add word-level propagators for the BV theory (OCamlPro/alt-ergo#944, OCamlPro/alt-ergo#1004, OCamlPro/alt-ergo#1007, OCamlPro/alt-ergo#1010, OCamlPro/alt-ergo#1011, OCamlPro/alt-ergo#1012, OCamlPro/alt-ergo#1040, OCamlPro/alt-ergo#1044, OCamlPro/alt-ergo#1054, OCamlPro/alt-ergo#1055, OCamlPro/alt-ergo#1056, OCamlPro/alt-ergo#1057, OCamlPro/alt-ergo#1065, OCamlPro/alt-ergo#1073, OCamlPro/alt-ergo#1144, OCamlPro/alt-ergo#1152) - Add interval domains and arithmetic propagators for the BV theory (OCamlPro/alt-ergo#1058, OCamlPro/alt-ergo#1083, OCamlPro/alt-ergo#1084, OCamlPro/alt-ergo#1085) - Native support for bv2nat of bit-vector normal forms (OCamlPro/alt-ergo#1154) - Fix incompleteness issues in the BV solver (OCamlPro/alt-ergo#978, OCamlPro/alt-ergo#979) - Abstract more arguments of AC symbols to avoid infinite loops when they contain other AC symbols (OCamlPro/alt-ergo#990) - Do not make irrelevant decisions in CDCL solver, improving performance slightly (OCamlPro/alt-ergo#1041) - Rewrite the ADT theory to use domains and integrate the enum theory into the ADT theory (OCamlPro/alt-ergo#1078, OCamlPro/alt-ergo#1086, OCamlPro/alt-ergo#1087, OCamlPro/alt-ergo#1091, OCamlPro/alt-ergo#1094, OCamlPro/alt-ergo#1138) - Rewrite the Intervals module entirely (OCamlPro/alt-ergo#1108) - Add maximize/minimize terms for matching (OCamlPro/alt-ergo#1166) - Internalize `sign_extend` and `repeat` (OCamlPro/alt-ergo#1192) - Run cross-propagators to completion (OCamlPro/alt-ergo#1221) - Support binary distinct on arbitrary bit-widths (OCamlPro/alt-ergo#1222) - Only perform optimization when building a model (OCamlPro/alt-ergo#1224) - Make sure domains do not overflow the default domain (OCamlPro/alt-ergo#1225) - Do not build unnormalized values in `zero_extend` (OCamlPro/alt-ergo#1226) ### Internal/library changes - Rewrite the Vec module (OCamlPro/alt-ergo#607) - Move printer definitions closer to type definitions (OCamlPro/alt-ergo#808) - Mark proxy names as reserved (OCamlPro/alt-ergo#836) - Use a Zarith-based representation for numbers and bit-vectors (OCamlPro/alt-ergo#850, OCamlPro/alt-ergo#943) - Add native support for (bvnot) in the BV solver (OCamlPro/alt-ergo#856) - Add constant propagators for partially interpreted functions (OCamlPro/alt-ergo#869) - Remove `Util.failwith` in favor of `Fmt.failwith` (OCamlPro/alt-ergo#872) - Add more `Expr` smart constructors (OCamlPro/alt-ergo#877, OCamlPro/alt-ergo#878) - Do not use existential variables for integer division (OCamlPro/alt-ergo#881) - Preserve `Subst` literals to prevent accidental incompleteness (OCamlPro/alt-ergo#886) - Properly start timers (OCamlPro/alt-ergo#924) - Compute a concrete representation of a model instead of performing (OCamlPro/alt-ergo#925) - Allow direct access to the SAT API in the Alt-Ergo library computations during printing (OCamlPro/alt-ergo#927) - Better handling for step limit (OCamlPro/alt-ergo#936) - Add a generic option manager to deal with the dolmen state (OCamlPro/alt-ergo#951) - Expose an imperative SAT API in the Alt-Ergo library (OCamlPro/alt-ergo#962) - Keep track of the SMT-LIB mode (OCamlPro/alt-ergo#971) - Add ability to decide on semantic literals (OCamlPro/alt-ergo#1027, OCamlPro/alt-ergo#1118) - Preserve trigger order when parsing quantifiers with multiple trigger (OCamlPro/alt-ergo#1046). - Store domains inside the union-find module (OCamlPro/alt-ergo#1119) - Remove some polymorphic hashtables (OCamlPro/alt-ergo#1219) ### Build and integration - Drop support for OCaml <4.08.1 (OCamlPro/alt-ergo#803) - Use dune-site for the inequalities plugins. External pluginsm ust now be registered through the dune-site plugin mechanism in the `(alt-ergo plugins)` site to be picked up by Alt-Ergo (OCamlPro/alt-ergo#1049). - Add a release workflow (OCamlPro/alt-ergo#827) - Add a Windows workflow (OCamlPro/alt-ergo#1203) - Mark the dune.inc file as linguist-generated to avoid huge diffs (OCamlPro/alt-ergo#830) - Use GitHub Actions badges in the README (OCamlPro/alt-ergo#882) - Use `dune build @check` to build the project (OCamlPro/alt-ergo#887) - Enable warnings as errors on the CI (OCamlPro/alt-ergo#888) - Uniformization of internal identifiers generation (OCamlPro/alt-ergo#905, OCamlPro/alt-ergo#918) - Use an efficient `String.starts_with` implementation (OCamlPro/alt-ergo#912) - Fix the Makefile (OCamlPro/alt-ergo#914) - Add `Logs` dependency (OCamlPro/alt-ergo#1206) - Use `dynamic_include` to include the generated file `dune.inc` (OCamlPro/alt-ergo#1199) - Support Windows (OCamlPro/alt-ergo#1184,OCamlPro/alt-ergo#1189,OCamlPro/alt-ergo#1195,OCamlPro/alt-ergo#1199,OCamlPro/alt-ergo#1200) - Wrap the library `Alt_ergo_prelude` (OCamlPro/alt-ergo#1223) ### Testing - Use --enable-assertions in tests (OCamlPro/alt-ergo#809) - Add a test for push/pop (OCamlPro/alt-ergo#843) - Use the CDCL solver when testing model generation (OCamlPro/alt-ergo#938) - Do not test .smt2 files with the legacy frontend (OCamlPro/alt-ergo#939) - Restore automatic creation of .expected files (OCamlPro/alt-ergo#941) ### Documentation - Add a new example for model generation (OCamlPro/alt-ergo#826) - Add a Pygments lexer for the Alt-Ergo native language (OCamlPro/alt-ergo#862) - Update the current authors (OCamlPro/alt-ergo#865) - Documentation of the `Enum` theory (OCamlPro/alt-ergo#871) - Document `Th_util.lit_origin` (OCamlPro/alt-ergo#915) - Document the CDCL-Tableaux solver (OCamlPro/alt-ergo#995) - Document Windows support (OCamlPro/alt-ergo#1216) - Remove instructions to install Alt-Ergo on Debian (OCamlPro/alt-ergo#1217) - Document optimization feature (OCamlPro/alt-ergo#1231)
This patch adds interval domains to the Bitv_rel module, as well as
interreductions between the bitlist and interval domains following:
Sharpening Constraint Programming approaches for Bit-Vector Theory.
Zakaria Chihani, Bruno Marre, François Bobot, Sébastien Bardin.
CPAIOR 2017. International Conference on AI and OR Techniques in
Constraint Programming for Combinatorial Optimization Problems, Jun
2017, Padova, Italy.
More precisely:
The
Intervals
module is extended to support theextract
operation, which is used to propagate between bit-vector compositions and their components;The interreductions are implemented using the new
Bitlist.increase_lower_bound
,Bitlist.decrease_upper_bound
, and the newshared_msb
helper inBitv_rel
;Propagations are performed by alternating propagations until fixpoint in each domain, followed by interreductions and propagations until fixpoint in the other domain, until reaching a fixpoint for the whole procedure. It is not clear that this is the best strategy; the goal is to try and limit interreductions since they are relatively expensive but we should revisit this once more operations are supported.
For now, only the
bvule
,bvult
,bvugt
andbvuge
primitives are supported as built-in bit-vector operations; other operations such asbvadd
are still encoded usingbv2nat
. These operations will be migrated to bit-vector primitives in a follow-up PR.Finally, there are some tests for the tricky bits (
Intervals.extract
and the interreduction primitives) using QCheck.