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Also fixes to C backend for compiling MIPS spec to C
- Fix an issue with const correctness in internal_vector_update
functions generated by C backend
- Add builtins for MIPS to sail.h
- Fix an issue where reg_deref didn't work when called on pointers to
large bitvectors, i.e. vectors containing references to large
bitfields as in the MIPS TLB code
- Various bug fixes and changes for running U-boot on ARM model,
including for interpreter and OCaml compilation.
- Fix memory leak issues and incorrect shadowing for foreach loops
- Update C header file. Fixes memory leak in memory read/write
builtins.
- Add aux constructor to ANF representation to hold environment
information.
- Fix undefined behavior caused by optimisation left shifting uint64_t
vectors 64 or more times. Unfortunately there's more issues because
the same happens for X >> 64 right shifts. It would make sense for
this to be zero, because that would guarantee the property that ((X
>> n) >> m) == (X >> (n + m)) but we probably need to do (X >> (n -
1) >> 1) in the optimisation to ensure that we don't cause
UB. Shifting by 63 and then by 1 is well-defined, but shifting by 64
in one go isn't according to the C standard. This issue with
right-shifts only occurs for zero-length vectors, so it's not a huge
deal, but it's still annoying.
- Add versions of print_bits and print_int that print to
stderr. Follows OCaml convention of print/prerr. Should make things
more explicit. Different backends had different ideas about where
print should output to, not every backend needs to have this
(e.g. theorem prover backends don't need to print) but having both
stderr and stdout seperate and clear is useful for executable models
(UART needs to be stdout, debug messages should be stderr).
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Also clean up some library functions a bit, and add some missing failure
handling variants of division operations on bitvectors.
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They are used in various specs and test cases.
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(note that they're already declared in lib/arith.sail)
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definitions from sail/lib.
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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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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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Rather than just using strings to represent literals, now use value
types from sail_lib.lem to represent them. This allows for expressions
to be evaluated at compile time, which will be useful for future
optimisations involving constant folding and propagation, and allows
the intermediate bytecode to be interpreted using the same lem
builtins that the shallow embedding uses.
To get this to work I had to tweak the build process slightly to allow
ml files to import lem files from gen_lib/. Hopefully this doesn't
break anything!
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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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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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removed IK_cond_branch, and added IK_branch
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passing tests.
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Makes bitvector typeclass instance dictionaries disappear from generated
Isabelle output.
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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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- Add support for some internal nodes to type checker
- Add more explicit type annotations during rewriting
- Remove hardcoded rewrites for E_vector_update etc from Lem pretty-printer;
these will be resolved by the type checker during rewriting now
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Also, rename a few functions for uniformity, e.g. bool_and -> and_bool
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(and fix up monomorphisation)
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Moreover, add support for pretty-printing (to Lem) vector access/update
operations for vectors with non-constant, but normalized start index.
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Requires version of Lem with real number support, currently at
https://bitbucket.org/bauereiss/lem/branch/reals
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- Remove start indices and indexing order from bitvector types. Instead add
them as arguments to functions accessing/updating bitvectors. These arguments
are effectively implicit, thanks to wrappers in prelude_wrappers.sail and a
"sizeof" rewriting pass.
- Add a typeclass for bitvectors with a few basic functions (converting to/from
bitlists, converting to an integer, getting and setting bits). Make both
monads use this interface, so that they work with both the bitlist and the
machine word representation of bitvectors.
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mono-experiments
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Note: The effect annotations of the execute function differ between CHERI and
MIPS, so I split out a new file mips_ast_decl.sail for MIPS with just the
initial declarations of ast, decode, and execute (with the right effects for
MIPS).
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mono-experiments
# Conflicts:
# src/gen_lib/sail_values.lem
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- Add back support for bit list representation of bit vectors, for backwards
compatibility in order to ease integration with the interpreter. For this
purpose, split out a file sail_operators.lem from sail_values.lem, and add a
variant sail_operators_mwords.lem for the machine word representation of
bitvectors. Currently, Sail is hardcoded to use machine words for the
sequential state monad, and bit lists for the free monad, but this could be
turned into a command line flag.
- Add a prelude_wrappers.sail file for glueing the Sail prelude to the Lem
library. The wrappers make use of sizeof expressions to extract type
information from bitvectors (length, start index) in order to pass it to the
Lem functions.
- Add early return support to the free monad, using a new constructor "Return
of 'r". As with the sequential monad, functions with early return are
wrapped into "catch_early_return", which extracts the return value at the end
of the function execution.
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Also: Merge remote-tracking branch 'origin/sail_new_tc' into experiments
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Make state monad parametric in register state, and generate a record with
registers from the Sail spec
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# Conflicts:
# src/type_internal.ml
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Implemented using the exception monad, by throwing and catching the return
value
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