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The `--force-logic` command line argument can be used to override a
logic specified in an input file or to set a logic when none is given.
Before this commit, both the `SmtEngine` and the parser were aware of
that argument. However, there were two issues if an input file didn't
specify a logic but `--force-logic` was used:
- Upon parsing `--force-logic`, the `SmtEngine` was informed about it
and set the logic to the forced logic. Then, the parser detected that
there was no `set-logic` command, so it set the logic to `ALL` and
emitted a corresponding warning. Finally, `SmtEngine::setDefaults()`
detected that `forceLogic` was set by the user and changed the logic
back to the forced logic. The warning was confusing and setting the
logic multiple times was not elegant.
- For eager bit-blasting, the logic was checked before resetting the
logic to the forced logic, so it would emit an error that eager
bit-blasting couldn't be used with the logic (which was `ALL` at that
point of the execution). This was a problem in the competition because
our runscript parses the `set-logic` command to decide on the
appropriate arguments to use and passes the logic to CVC4 via
`--force-logic`.
This commit moves the handling of `--force-logic` entirely into the
parser. The rationale for that is that this is not an API-level issue
(if you use the API you simply set the logic you want, forcing a
different logic in addition doesn't make sense) and simplifies the
handling of the option (no listeners need to be installed and the logic
is set only once). This commit also removes the option to set the logic
via `(set-option :cvc4-logic ...)` because it complicates matters (e.g.
which method of setting the logic takes precedence?). For the CVC and
the TPTP languages the commit creates a command to set the logic in
`SmtEngine` when the logic is forced in the parser instead of relying on
`SmtEngine` to figure it out itself.
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`let_shadowing.smt2` uses dumping to test our printing infrastructure.
Since some builds do not support dumping, this commit disables that
regression for non-dumping builds. Additionally, it enables an error
message when trying to dump with a muzzled build and corrects the output
of `--show-config` to indicate that muzzled builds cannot dump.
Previously, the dumping output of a muzzled build was just silently
empty.
Most of the changes in `dump.cpp` are due to reformatting.
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Fixes #3005. When printing nodes, we introduce `let` expressions on the
fly. However, when doing that, we have to be careful that we don't
shadow existing variables with the same name. When quantifiers are
involved, we do not descend into the quantifiers to avoid letifying
terms with bound variables that then go out of scope (see #1863). Thus,
to avoid shadowing variables appearing in quantifiers, we have to
collect all the variables appearing in that term to make sure that the
let does not shadow them. In #3005, the issue was caused by a `let` that
was introduced outside of a quantifier and then was shadowed in the body
of the quantifier by another `let` introduced for that body.
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Due to issues in the current proof code, this commit also disables proof
checking for five QF_LRA benchmarks (see issue #2855).
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This commit adds a check to make sure that the result of a `(check-sat)`
call matches the expected result set via `(set-info :status ...)`. In
doing so, it also fixes an issue where CVC4 would crash if asked for the
unsat core after setting the status to `unsat` but before calling
`(check-sat)` (see regression for concrete example). This happened
because CVC4 was storing the expected result and the computed result
both in the same variable (the expected result wasn't really being used
though). This commit keeps track of the expected result and the computed
result in separate variables to fix that issue.
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When printing an empty symbol name, which can appear in an SMT2 file as
`||`, we were printing the empty string instead of quoting the symbol.
This commit fixes the issue and adds a regression test.
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Fixes #3020. Boolean terms that appear in other terms, e.g. a Boolean
array index, are replaced by `BOOLEAN_TERM_VARIABLE`s to make sure that
they are handled properly in theory combination. When doing this
replacement, an equality of the form `(= <Boolean term> <Boolean term
variable)` is added to the assertions. The problem was that
`Theory::ppAssert()` would derive a substitution when this equality was
registered. The commit fixes the problem by not allowing to add
substitutions for `BOOLEAN_TERM_VARIABLE`s.
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Fixes #2932. fp.roundToIntegral was rounding some very small subnormals up to
between 1 and 2, which is A. wrong and B. not idempotent. The
corresponding symfpu update fixes this as it was an overflow caused
by the unpacked significand not being able to represent an extra
significand bits.
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Although CVC4's behaviour is actually correct, this is to make
things a bit clearer and prevent confusion in the future.
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When bit-blasting eagerly, we were not assigning values to the Boolean
variables in the `TheoryModel`. With eager bit-blasting, the BV SAT
solver gets all (converted) terms, including the Boolean ones, so
`EagerBitblaster::collectModelInfo()` is responsible for assigning
values to Boolean variables. However, it has only been assigning values
to bit-vector variables, which lead to wrong models. This commit fixes
the issue by asking the `CnfStream` for the Boolean variables, querying
the SAT solver for their value, and assigning them in the `TheoryModel`.
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Fixes #2958.
The issue was: we had substr(x,0,2) in R, and the "derivable substitution" modifed this to substr(substr(x,0,2),0,2) in R, since substr(x,0,2) was the representative of x (which is a bad choice, but regardless is legal). Then decomposition inference asked "can i reduce substr(substr(x,0,2),0,2) in R"? It determines substr(substr(x,0,2),0,2) in R rewrites to substr(x,0,2) in R, which is already true. However, substr(x,0,2) in R was what we started with.
The fix makes things much more conservative: we never mark extended functions reduced based on decomposition, since there isnt a strong argument based on an ordering.
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The most recent version of SMT-LIB defines bv{add,mul,and,or,xor,xnor}
[0, 1] as left-associative. CVC4 treats all but bvxnor as having
variable arity anyway but the arity check was too strict when using
`--strict-parsing`. This commit changes the strict parsing check. For
bvxnor, it adds code to the parser that expands an application of bvxnor
into multiple applications of a binary bvxnor if needed.
References:
[0] http://smtlib.cs.uiowa.edu/theories-FixedSizeBitVectors.shtml (bvand,
bvor, bvadd, bvmul)
[1] http://smtlib.cs.uiowa.edu/logics-all.shtml#QF_BV (bvxor, bvxnor)
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For a simple query `(not (= (fp.isSubnormal x) false))`, we were getting
a wrong model. The issue was that `(sign x)` was not assigned a value
and did not appear in the shared terms. In
`TheoryFp::collectModelInfo()`, however, we generate an expression that
connects the components of `x` to `x`, which contains `(sign x)`. As a
result, the normalization while building a model did not result in a
constant. This commit fixes the issue by marking `(sign x)` (and
`(significand x)`) as assignable. Assignable terms can take any value
while building a model if there is no existing value.
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ASAN was reporting memory leaks in regression tests that were using
subsolvers. First, I am going to describe the origin of the leaks and
then the solution implemented in this commit.
Recall an `Expr` stores the `NodeManager` that the internal node is
associated with. `Node::toExpr()` converts a `Node` to an `Expr` and
assumes that the active `NodeManager` (returned by
`NodeManager::currentNM()` is the one associated with the node. In
`ExportPrivate::exportInternal()`, when we were exporting a skolem, we
created a skolem in the target `NodeManager` by calling
`NodeManager::mkSkolem()` (`ExprManager`s do not support the creation of
skolems) but then we called `Node::toExpr()` on the resulting skolem
while the origin `NodeManager` was the active `NodeManager`. One of the
issues of having the wrong `NodeManager` in the `Expr` is that when the
`Expr` is destroyed and the internal node's refcount reaches zero in
destructor of `Expr`, then the node value associated with the node is
added to the set of zombie nodes (nodes waiting to be garbage collected
or resurrected) of the wrong `NodeManager`. The problem here is that the
set of zombie nodes uses the node id to hash and compare nodes. Node
ids, however, are only unique within a given `NodeManager`. Thus, if we
have two nodes with the same id from different `NodeManager`s and both
reach refcount zero in the context of the same `NodeManager`, only one
of them will end up in the set of zombies and thus only that one will be
freed.
Using a subsolver realiably triggered this issue.
`ExportPrivate::exportInternal()` stored the `Expr` with the wrong
`NodeManager` in an `ExprManagerMapCollection` which associates
variables in the original `ExprManager` with the variables in the target
`ExprManager`. When we created a subsolver, we created the
`ExprManagerMapCollection` before creating our subsolver, so it was
deleted after the subsolver and so deleting the
`ExprManagerMapCollection` deleted the last reference to `Expr`s holding
skolem nodes associated with the wrong `NodeManager`.
This commit fixes the issue by making sure that the correct
`NodeManager` is in scope when converting the skolem/bound variable
nodes to an `Expr`. It also swaps the creation order of
`ExprManagerMapCollection` and `ExprManager` to make sure that
`ExprManagerMapCollection` is deleted before the `ExprManager` that the
`Expr`s belong to. Additionally, the commit makes it harder to make a
similar mistake by asserting that the `Expr`s in the
`ExprManagerMapCollection` are associated with the expected
`ExprManager`s. Finally, it adds an assertion that tries to identify
such issues by checking whether the list of zombies contains a node with
the same id but located at a different address.
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