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This commit primarily changes how existential types are bound in
letbindings. Essentially, the constraints on both numeric and
existentially quantified types are lifted into the surrounding type
context automatically, so in
```
val f : nat -> nat
let x = f(3)
```
whereas x would have had type nat by default before, it'll now have
type atom('n) with a constraint that 'n >= 0 (where 'n is some fresh
type variable). This has several advantages: x can be passed to
functions expecting an atom argument, such as a vector indexing
operation without any clunky cast functions - ex_int, ex_nat, and
ex_range are no longer required. The let 'x = something() syntax is
also less needed, and is now only really required when we specifically
want a name to refer to x's type. This changes slightly the nature of
the type pattern syntax---whereas previously it was used to cause an
existential to be destructured, it now just provides names for an
automatically destructured binding. Usually however, this just works
the same.
Also:
- Fixed an issue where the rewrite_split_fun_constr_pats rewriting
pass didn't add type paramemters for newly added type variables in
generated function parameters.
- Updated string_of_ functions in ast_util to reflect syntax changes
- Fixed a C compilation issue where elements of union type
constructors were not being coerced between big integers and 64-bit
integers where appropriate
- Type annotations in patterns now generalise, rather than restrict
the type of the pattern. This should be safer and easier to handle
in the various backends. I don't think any code we had was relying
on this behaviour anyway.
- Add inequality operator to lib/flow.sail
- Fix an issue whereby top-level let bindings with annotations were
checked incorrectly
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Fix a bug in initial check which caused X() = y to expect an additional parameter.
Some tweaks to sail2 emacs mode
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More work on Latex output
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definitions from sail/lib.
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Added library for simple integer arithmetic functions in lib/arith.sail
WIP TeX file for formatting latex output included in lib/sail.tex
Fixes for bugs in sail_lib
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First, the specialisation of option types has been fixed by allowing
the specialisation of constructor return types - this essentially
means that a constructor, such as Some : 'a -> option('a) can get
specialised to int -> option(int), rather than int -> option('a). This
means that these constructors are treated like GADTs internally. Since
this only happens just before the C translation, I haven't put much
effort into making this very robust so far.
Second, there was a bug in C compilation for the typing of return
expressions in non-unit contexts, which has been fixed.
Finally support for vector literals that are non-bitvectors has been
added.
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In particular, improve indentation of if-expressions, and provide infix syntax
for monadic binds in Isabelle, allowing Lem to preserve source whitespace.
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Some functions are partial, e.g. converting a bitvector to an integer, which
might fail for the bit list representation due to undefined bits. Undefined
cases can be handled in different ways:
- call Lem's failwith, which maps to undefined/ARB in Isabelle and HOL (the
default so far),
- return an option type,
- raise a failure in the monad, or
- use a bitstream oracle to resolve undefined bits.
This patch adds different versions of partial functions corresponding to those
options. The desired behaviour can be selected by choosing a binding in the
Sail prelude. The naming scheme is that the failwith version is the default,
while the other versions have the suffixes _maybe, _fail, and _oracle,
respectively.
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The state monad currently assumes that tags are written to and read from
properly aligned addresses (since it does not know the capability size used in
the Sail model). This change allows the Sail model to pass in the aligned
address(es) even if data is written to an unaligned address. There might be
better ways to model tag writing, but this approach seems rather general.
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This simplifies reasoning in Isabelle.
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Fixed an issue whereby an option constructor that was never
constructed, but only matched on, would cause compilation to
fail. Temporarily fixed an issue where union types that can be
entirely stack-allocated were not being treated as such, by simply
heap-allocating all unions. Need to adapt the code generator to handle
this case properly. Fixed a further small issue whereby multiple union
types would confuse the type specialisation pass.
Added a test case for compiling option types.
RISCV now generates C code, but there are still some bugs that need to
be squashed before it compile and work.
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Add a flag to Sail that allows for an image of an elf file to be
dumped in a simple format using linksem, used as
sail -elf test.elf -o test.bin
This image file can then be used by a compiled C version of a sail
spec as with ocaml simply by
./a.out test.bin
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Previously union types could have no-argument constructors, for
example the option type was previously:
union option ('a : Type) = {
Some : 'a,
None
}
Now every union constructor must have a type, so option becomes:
union option ('a : Type) = {
Some : 'a,
None : unit
}
The reason for this is because previously these two different types of
constructors where very different in the AST, constructors with
arguments were used the E_app AST node, and no-argument constructors
used the E_id node. This was particularly awkward, because it meant
that E_id nodes could have polymorphic types, i.e. every E_id node
that was also a union constructor had to be annotated with a type
quantifier, in constrast with all other identifiers that have
unquantified types. This became an issue when monomorphising types,
because the machinery for figuring out function instantiations can't
be applied to identifier nodes. The same story occurs in patterns,
where previously unions were split across P_id and P_app nodes - now
the P_app node alone is used solely for unions.
This is a breaking change because it changes the syntax for union
constructors - where as previously option was matched as:
function is_none opt = match opt {
Some(_) => false,
None => true
}
it is now matched as
function is_none opt = match opt {
Some(_) => false,
None() => true
}
note that constructor() is syntactic sugar for constructor(()), i.e. a
one argument constructor with unit as it's value. This is exactly the
same as for functions where a unit-function can be called as f() and
not as f(()). (This commit also makes exit() work consistently in the
same way) An attempt to pattern match a variable with the same name as
a union-constructor now gives an error as a way to guard against
mistakes made because of this change.
There is probably an argument for supporting the old syntax via some
syntactic sugar, as it is slightly prettier that way, but for now I
have chosen to keep the implementation as simple as possible.
The RISCV spec, ARM spec, and tests have been updated to account for
this change. Furthermore the option type can now be included from
$SAIL_DIR/lib/ using
$include <option.sail>
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Currently ignored in the state monad
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Add an Undefined outcome to the prompt monad that asks the environment for a
Boolean value. For the state monad, add fields for a random generator and a
seed (currently of type nat) to the state.
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The suffix _lemmas is more descriptive than _extras.
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Architecture-specific lemmas about concrete registers and types are generated
and written to a file <prefix>_lemmas.thy, generic lemmas are in the
theories *_extras.thy in lib/isabelle. In particular, State_extras contains
simplification lemmas about the lifting from prompt to state monad.
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Fixed an issue with pattern matching on enums
Fixed an issue whereby fix_early_returns would cause memory leaks
Added optimizations for some of the builtins used in the decode
function. Optimizations are turned on with the -O flag.
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Add support for short-ciruiting and/or. I forgot about this in the
original ANF specification and not having it causes problems for the
ARM spec.
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Now compiles to C and builds a working executable. Just need to
correctly implement all the library builtins (some are still stubs),
and it should work.
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Turns out the __TakeColdReset function is actually in the v8.3 XML. I
went and looked for it, and it's there, it just wasn't being picked up
by ASL parser because it's not called from any instructions. I added a
new field to the json config files for ASL parser that can tell it
about any such special functions that it should guarantee to include.
Also fixed a bug in C loop compilation
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Generate only one Lem model based on the prompt monad (instead of two models
with different monads), and add a lifting from prompt to state monad. Add some
Isabelle lemmas about the monad lifting.
Also drop the "_embed" and "_sequential" suffixes from names of generated
files.
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- Use simplified monad type (e.g., without the with_aux constructors that are
not needed by the shallow embedding).
- Add support for registers with arbitrary types (e.g., records, enumerations,
vectors of vectors). Instead of using bit lists as the common representation
of register values at the monad interface, use a register_value type that is
generated per spec as a union of all register types that occur in the spec.
Conversion functions between register_value and concrete types are generated.
- Use the same representation of register references as the state monad, in
preparation of rebasing the state monad onto the prompt monad.
- Split out those types from sail_impl_base.lem that are used by the shallow
embedding into a new module sail_instr_kinds.lem, and import that. Removing
the dependency on Sail_impl_base from the shallow embedding avoids name clashes
between the different monad types.
Not yet done:
- Support for reading/writing register slices. Currently, a rewriting pass
pushes register slices in l-expressions to the right-hand side, turning a
write to a register slice into a read-modify-write. For interfacing with the
concurreny model, we will want to be more precise than that (in particular
since some specs represent register files as big single registers containing a
vector of bitvectors).
- Lemmas about the conversion functions to/from register_value should be
generated automatically.
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to help Lem go from a general type `bits('n)` to a specific type `bits(16)`
at a case split, and the other way around for a returned value.
Doesn't handle function clause patterns yet
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Can now compile things like early returns. The same approach should
work for exception handling as well. Once that's in place, just need
to work a bit more on getting union types to work + the library of
builtins, then we should be able to compile and run some of our specs
via C. Also added some documentation in comments for the general
approach taken when compiling (need many more though).
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Makes bitvector typeclass instance dictionaries disappear from generated
Isabelle output.
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combinators)
Add Isabelle-specific theories imported directly after monad definitions, but
before other combinators. These theories contain lemmas that tell the function
package how to deal with monadic binds in function definitions.
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Also refactored the hand written ARM prelude and pulled out some common functionality into files in sail/lib
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- Remove vector start indices
- Library refactoring: Definitions in sail_operators.lem now use Bitvector
type class and work for both bit list and machine word representations
- Add Lem bindings to AArch64 and RISC-V preludes
TODO: Merge specialised machine word operations from sail_operators_mwords into
sail_operators.
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(no vector type start position, comment syntax)
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Fixed test cases for ocaml backend and interpreter
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