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test/typecheck/pass/tautology.sail constaints tests of various boolean
properties, e.g.
// de Morgan
_prove(constraint(not('p | 'q) <--> not('p) & not('q)));
_prove(constraint(not('p & 'q) <--> not('p) | not('q)));
introduce a new _not_prove case which allows us to assert in tests
that a constraint is not provable. This test essentially tests that
constraints map to sensible problems in the SMT solver, without
testing flow typing or any other features.
Add a script test/typecheck/update_errors.sh, which regenerates the
expected error messages. Testing that type-checking failures is
important, but can be brittle when the error messages change for
inconsequential reasons. This script automates fixing this.
Also ensure that this test case works correctly in Lem
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We should infer type variable kinds better in initial_check.ml, but we really don't want to have to deal
with that everywhere, especially when we can no longer easily cheat and assume KOpt_none implies K_int.
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Remove some dead code in Pretty_print_common
Start thinking a bit about Minisail-esque syntactic sugar in initial_check
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* Improve type inference for numeric if statements (if_infer test)
* Correctly handle constraints for existentially quantified constructors (constraint_ctor test)
* Canonicalise all numeric types in function arguments, which
triggers some weird edge cases between parametric polymorphism and
subtyping of numeric arguments
* Because of this eq_int, eq_range, and eq_atom etc become identical
* Avoid duplicating destruct_exist in Env
* Handle some odd subtyping cases better
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Change Typ_arg_ to A_. We use it a lot more now typ_arg is used instead of
uvar as the result of unify. Plus A_ could either stand for argument, or
Any/A type which is quite appropriate in most use cases.
Restore instantiation info in infer_funapp'. Ideally we would save this
instead of recomputing it ever time we need it. However I checked and
there are over 300 places in the code that would need to be changed to add
an extra argument to E_app. Still some issues causing specialisation to
fail however.
Improve the error message when we swap how we infer/check an l-expression,
as this could previously cause the actual cause of a type-checking failure
to be effectively hidden.
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On a new branch because it's completely broken everything for now
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Mostly this is to change how we desugar types in order to make us more
flexible with what we can parse as a valid constraint as
type. Previously the structure of the initial check forced some
awkward limitations on what was parseable due to how the parse AST is
set up.
As part of this, I've taken the de-scattering of scattered functions
out of the initial check, and moved it to a re-writing step after
type-checking, where I think it logically belongs. This doesn't change
much right now, but opens up some more possibilities in the future:
Since scattered functions are now typechecked normally, any future
module system for Sail would be able to handle them specially, and the
Latex documentation backend can now document scattered functions
explicitly, rather than relying on hackish 'de-scattering' logic to
present documentation as the functions originally appeared.
This has one slight breaking change which is that union clauses must
appear before their uses in scattered functions, so
union ast = Foo : unit
function clause execute(Foo())
is ok, but
function clause execute(Foo())
union ast = Foo : unit
is not. Previously this worked because the de-scattering moved union
clauses upwards before type-checking, but as this now happens after
type-checking they must appear in the correct order. This doesn't
occur in ARM, RISC-V, MIPS, but did appear in Cheri and I submitted a
pull request to re-order the places where it happens.
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This makes dealing with records and field expressions in Sail much
nicer because the constructors are no longer stacked together like
matryoshka dolls with unnecessary layers. Previously to get the fields
of a record it would be either
E_aux (E_record (FES_aux (FES_Fexps (fexps, _), _)), _)
but now it is simply:
E_aux (E_record fexps, _)
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Rather than having K_aux (K_kind [BK_aux (BK_int, _)], _) represent
the Int kind, we now just have K_aux (K_int, _). Since the language is
first order we have no need for fancy kinds in the AST.
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They weren't needed for ASL parser like I thought they would be, and
they increase the complexity of dealing with constraints throughout
Sail, so just remove them.
Also fix some compiler warnings
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This brings Sail closer to MiniSail, and means that
type my_range 'n 'm = {'o, 'n <= 'o <= 'm. int('o)}
will work on the left hand side of a function type in the same way as
a regular built-in range type. This means that in principle neither
range nor int need be built-in types, as both can be implemented in
terms of int('n) (atom internally). It also means we can easily
identify type variables that need to be made into implict arguments,
with the criterion for that being simply any type variable that
doesn't appear in a base type on the LHS of the function, or only
appears on the RHS.
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We need to ensure that we expand type-synonyms when calculating which
types a register depends on during topological sorting in order to
place the undefined_type function in the correct place, even when type
is indirected through a function.
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Also some pretty printer improvements
Make all the tests use the same colours for green/red/yellow
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Remove Parse_ast.Int (for internal locations) as this was unused. Add
a Parse_ast.Unique constructor to create unique locations. Change
locate_X functions to take a function modifying locations, rather than
just replacing them and add a function unique : l -> l that makes
locations unique, such that `locate unique X` will make a locations in
X unique.
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There is no Reporting_complex, so it's not clear what the basic is
intended to signify anyway.
Add a GitHub issue link to any err_unreachable errors (as they are all
bugs)
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For example, for a function like
```
val aget_X : forall 'n, 0 <= 'n <= 31. int('n) -> bits(64)
function test(n : int) -> unit = {
let y = aget_X(n);
()
}
```
we get the message
> Could not resolve quantifiers for aget_X (0 <= 'ex7# & 'ex7# <= 31)
>
> Try adding named type variables for n : atom('ex7#)
>
> The property (0 <= n & n <= 31) must hold
which suggests adding a name for the type variable 'ex7#, and gives
the property in terms of the variable n. If we give n a type variable name:
```
val test : int -> unit
function test(n as 'N) = {
let y = aget_X(n);
()
}
```
It will suggest a constraint involving the type variable name
> Could not resolve quantifiers for aget_X (0 <= 'ex6# & 'ex6# <= 31)
>
> Try adding the constraint (0 <= 'N & 'N <= 31)
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Currently not enabled by default, the flag -Xconstraint_synonyms
enables them
For generating constraints in ASL parser, we want to be able to give
names to the constraints that we attach to certain variables. It's
slightly awkward right now when constraints get long complicated
because the entire constraint always has to be typed out in full
whenever it appears, and there's no way to abstract away from that.
This adds constraint synonyms, which work much like type synonyms
except for constraints, e.g.
constraint Size('n) = 'n in {1, 2, 4, 8} | 128 <= 'n <= 256
these constraints can then be used instead of the full constraint, e.g.
val f : forall 'n, where Size('n). int('n) -> unit
Unfortunatly we need to have a keyword to 'call' the constraint
synonym otherwise the grammer stops being LR(1). This could be
resolved by parsing all constraints into Parse_ast.atyp and then
de-sugaring them into constraints, which is what happens for
n-expressions already, but that would require quite a bit of work on
the parser.
To avoid this forcing changes to any other parts of Sail, the intended
invariant is that all constraints appearing anywhere in a type-checked
AST have no constraint synonyms, so they don't have to worry about
matching on NC_app, or calling Env.expand_typquant_synonyms (which
isn't even exported for this reason).
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Changes the representation of function types in the ast from
Typ_fn : typ -> typ
to
Typ_fn : typ list -> typ
to more accurately represent their use in the various backends, where we often compile functions to either their curried representations as in Lem and Isabelle, or just
multiple argument functions in C. There's still some oddity because a single pattern in a function clause can bind against multiple arguments, and maybe we want to
forbid this in the future. The syntax also hasn't changed (yet), so in theory this change shouldn't break anything (but it invariably will...).
In the future we would ideally require that a function with N arguments has exactly N patterns in its declaration, one for each argument so
f : (x, y) -> z
f _ = ...
would be disallowed (as _ matches both x and y), forcing
f(_, _) = z
this would simply quite a few things,
Also we could have a different syntax for function argument lists and tuples, because it's rather hard to define a function that actually takes a tuple with the syntax
how it is now.
Some issues I noticed when doing this refactoring:
Line 1926 of Coq translation. untuple_args_pat is maybe no longer needed? However there's still some funnyness where a pattern can be used to bind multiple function
arguments so maybe it still is.
Line 2306 of monomorphisation. I simplified the logic here. I think it's equivalent now, but I could be wrong.
Line 4517 of rewrites. I'm not sure what make_cstr_mappings is doing here, but hopefully the simpler version is the same.
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When converting to A-normal form I just used the type of the then
branch of if statements to get the type of the whole if statement -
usually they'd be the same, but with flow typing one of the branches
can have a false constraint, which then allows the optimizer to fit
any integer into a 64-bit integer causing an overflow. The fix is to
correctly use the type the typechecker gives for the whole if
statement.
Also add decimal_string_of_bits to the C output.
Rename is_reftyp to is_ref_typ to be more consistent with other
is_X_typ functions in Ast_util.
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When constructing expressions, we need to provide locations for the
generated expressions to give useful error messages. However adding
these at every mk_X function in ast_util would be very verbose,
especially for complex expressions.
Add new locate_X functions (with the one for expressions simply being
called locate), which take a location and recursively apply it to
every child node, e.g.
locate (gen_loc l) (mk_exp (... (mk_exp ..., mk_exp ...)))
would mark every part of the constructed expression as being generated
from code at location l.
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This really demonstrates why we should switch to Typ_fn being a typ
list * typ constructor because the implementation here feels *really*
hacky with dummy Typ_tup constructors being used to enforce single
arguments for constructors.
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Interpreter used a re-write (vector concat removal) that is dependent
on the vector_string_to_bit_list rewriting pass. This fixes the
interpreter to work without either vector concat removal, or turning
bitstrings into vector literals like [bitzero, bitzero, bitone]. This
has the upside of reducing the number of steps the interpreter needs
for working with bitvectors so should improve interpreter performance.
We also now test all the C compilation tests behave the same using the
interpreter. Currently the real number tests fail due to limitations
of Lem's rational library (this must be fixed in Lem). This required
supporting configuration registers in the interpreter. As such the
interpreter was refactored to more cleanly process registers when
building an initial global state. The functions are also collected
into the global state, which removes the need to search for them in
the AST every time a function call happens. This should not only
improve performance, but also removes the need to pass an AST into the
interpretation functions.
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Test the builtin functions by compiling them to C, OCaml, and OCaml
via Lem. Split up some of the longer builtin test programs to avoid
stack overflows when compiling to OCaml, as 3000+ line long blocks can
cause issues with some re-writing steps.
Also test constant-folding with builtins (this should reduce the
asserts in these files to assert true), and also test constant folding
with the C compilation.
Fix a bug whereby vectors with heap-allocated elements were not
initialized correctly.
Fix a bug caused by compiling and optimising empty vector literals.
Fix an OCaml test case that broke due to the ref type being used. Now
uses references to registers.
Fix a bug where Sail would output big integers that lem can't
parse. Checks if integer is between Int32.min_int and Int32.max_int
and if not, use integerOfString to represent the integer. Really this
should be fixed in Lem.
Make the python test runner script the default for testing builtins
and running the C compilation tests in test/run_tests.sh
Add a ocaml_build_dir option that sets a custom build directory for
OCaml. This is needed for running OCaml tests in parallel so the
builds don't clobber one another.
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Add additional well-formedness check when calling typing rules
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Rather than exporting the implementation of type annotations as
type tannot = (Env.t * typ * effect) option
we leave it abstract as
type tannot
Some additional functions have been added to type_check.mli to work
with these abstract type annotations. Most use cases where the type
was constructed explicitly can be handled by using either mk_tannot or
empty_tannot. For pattern matching on a tannot there is a function
val destruct_tannot : tannot -> (Env.t * typ * effect) option
Note that it is specifically not guaranteed that using mk_tannot on
the elements returned by destruct_tannot re-constructs the same
tannot, as destruct_tannot is only used to give the old view of a type
annotation, and we may add additional information that will not be
returned by destruct_tannot.
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These match the new ASL pattern constructors:
- !p matches if the pattern p does not match
- { p1, ... pn } matches if any of the patterns p1 ... pn match
We desugar the set pattern "{p1, ... pn}" into "p1 | (p2 | ... pn)".
ASL does not have pattern binding but Sail does. The rules at the
moment are that none of the pattern can contain patterns. This could
be relaxed by allowing "p1 | p2" to bind variables provided p1 and p2
both bind the same variables.
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E_internal_cast, E_sizeof_internal, E_internal_exp,
E_internal_exp_user, E_comment, and E_comment_struc were all
unused. For a lem based interpreter, we want to be able to compile it
to iUsabelle, and due to slowness inherent in Isabelle's datatype
package we want to remove unused constructors in our AST type.
Also remove the lem_ast backend - it's heavily bitrotted, and for
loading the ARM ast into the interpreter it's just not viable to use
this approach as it just doesn't scale. We really need a way to be
able to serialise and deserialise the AST efficiently in Lem.
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Makes the generated undefined functions smaller, easier to read, and
avoids excessive memory usage in Coq (e.g., for large AST types).
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Registers can now be marked as configuration registers, for example:
register configuration CFG_RVBAR = 0x1300000
They work like ordinary registers except they can only be set by
functions with the 'configuration' effect and have no effect when
read. They also have an initialiser, like a let-binding. Internally
there is a new reg_dec constructor DEC_config. They are intended to
represent configuration parameters for the model, which can change
between runs, but don't change during execution. Currently they'll
only work when compiled to C. Internally registers can now have custom
effects for reads and writes rather than just rreg and wreg, so the
type signatures of Env.add_register and Env.get_register have changed,
as well as the Register lvar, so in the type checker we now write:
Env.add_register id read_effect write_effect typ
rather than
Env.add_register id typ
For the corresponding change to ASL parser there's a function
is_config in asl_to_sail.ml which controls what becomes a
configuration register for ARM. Some things we have to keep as
let-bindings because Sail can't handle them changing at runtime -
e.g. the length of vectors in other top-level definitions. Luckily
__SetConfig doesn't (yet) try to change those options.
Together these changes allow us to translate the ASL __SetConfig
function, which means we should get command-line option compatibility
with ArchEx for running the ARM conformance tests.
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(involved some manual tinkering with gitignore, type_check, riscv)
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(should really make the Lem pretty printer use the solver properly,
but this is a useful stopgap)
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1. Experiment with allowing some flow typing on mutable variables for
translating ASL in a more idiomatic way. I realise after updating some
of the test cases that this could have some problematic side effects
for lem translation, where mutable variables are translated into
monadic code. We'd need to ensure that whatever flow typing happens
for mutable variables also works for monadic code, including within
transformed loops. If this doesn't work out some of these changes may
need to be reverted.
2. Make the type inference for l-expressions a bit smarter. Splits the
type checking rules for l-expressions into a inference part and a
checking part like the other bi-directional rules. Should not be able
to type check slightly more l-expresions, such as nested vector slices
that may not have checked previously.
The l-expression rules for vector patterns should be simpler now, but
they are also more strict about bounds checking. Previously the bounds
checks were derived from the corresponding operations that would
appear on the RHS (i.e. LEXP_vector would get it's check from
vector_access). This meant that the l-expression bounds checks could
be weakend by weakening the checks on those operations. Now this is no
longer possible, there is a -no_lexp_bounds_check option which turns
of bounds checking in l-expressions. Currently this is on for the
generated ARM spec, but this should only be temporary.
3. Add a LEXP_vector_concat which mirrors P_vector_concat except in
l-expressions. Previously there was a hack that overloaded LEXP_tup
for this to translate some ASL patterns, but that was fairly
ugly. Adapt the rewriter and other parts of the code to handle
this. The rewriter for lexp tuple vector assignments is now a rewriter
for vector concat assignments.
4. Include a newly generated version of aarch64_no_vector
5. Update the Ocaml test suite to use builtins in lib/
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