Files
wasmtime/meta/cretonne/__init__.py
Jakob Stoklund Olesen 13d33d5a7a Introduce predicates.
Predcates are boolean functions. There will be ISA predicates and instruction
predicates.

The ISA predicates will be turned into member functions on the generated Flags
structs.
2016-08-11 16:40:54 -07:00

972 lines
31 KiB
Python

"""
Cretonne meta language module.
This module provides classes and functions used to describe Cretonne
instructions.
"""
import re
import importlib
from collections import namedtuple
camel_re = re.compile('(^|_)([a-z])')
def camel_case(s):
"""Convert the string s to CamelCase"""
return camel_re.sub(lambda m: m.group(2).upper(), s)
class Setting(object):
"""
A named setting variable that can be configured externally to Cretonne.
Settings are normally not named when they are created. They get their name
from the `extract_names` method.
"""
def __init__(self, doc):
self.name = None # Assigned later by `extract_names()`.
self.__doc__ = doc
# Offset of byte in settings vector containing this setting.
self.byte_offset = None
self.group = SettingGroup.append(self)
def predicate_context(self):
"""
Return the context where this setting can be evaluated as a (leaf)
predicate.
"""
return self.group
class BoolSetting(Setting):
"""
A named setting with a boolean on/off value.
:param doc: Documentation string.
:param default: The default value of this setting.
"""
def __init__(self, doc, default=False):
super(BoolSetting, self).__init__(doc)
self.default = default
def default_byte(self):
"""
Get the default value of this setting, as a byte that can be bitwise
or'ed with the other booleans sharing the same byte.
"""
if self.default:
return 1 << self.bit_offset
else:
return 0
class NumSetting(Setting):
"""
A named setting with an integral value in the range 0--255.
:param doc: Documentation string.
:param default: The default value of this setting.
"""
def __init__(self, doc, default=0):
super(NumSetting, self).__init__(doc)
assert default == int(default)
assert default >= 0 and default <= 255
self.default = default
def default_byte(self):
return self.default
class EnumSetting(Setting):
"""
A named setting with an enumerated set of possible values.
The default value is always the first enumerator.
:param doc: Documentation string.
:param args: Tuple of unique strings representing the possible values.
"""
def __init__(self, doc, *args):
super(EnumSetting, self).__init__(doc)
assert len(args) > 0, "EnumSetting must have at least one value"
self.values = tuple(str(x) for x in args)
self.default = self.values[0]
def default_byte(self):
return 0
class SettingGroup(object):
"""
A group of settings.
Whenever a :class:`Setting` object is created, it is added to the currently
open group. A setting group must be closed explicitly before another can be
opened.
:param name: Short mnemonic name for setting group.
:param parent: Parent settings group.
"""
# The currently open setting group.
_current = None
def __init__(self, name, parent=None):
self.name = name
self.parent = parent
self.settings = []
self.predicates = []
self.open()
def open(self):
"""
Open this setting group such that future new settings are added to this
group.
"""
assert SettingGroup._current is None, (
"Can't open {} since {} is already open"
.format(self, SettingGroup._current))
SettingGroup._current = self
def close(self, globs=None):
"""
Close this setting group. This function must be called before opening
another setting group.
:param globs: Pass in `globals()` to run `extract_names` on all
settings defined in the module.
"""
assert SettingGroup._current is self, (
"Can't close {}, the open setting group is {}"
.format(self, SettingGroup._current))
SettingGroup._current = None
if globs:
from predicates import Predicate
for name, obj in globs.iteritems():
if isinstance(obj, Setting):
assert obj.name is None, obj.name
obj.name = name
if isinstance(obj, Predicate):
assert obj.name is None
obj.name = name
self.predicates.append(obj)
@staticmethod
def append(setting):
g = SettingGroup._current
assert g, "Open a setting group before defining settings."
g.settings.append(setting)
return g
# Kinds of operands.
#
# Each instruction has an opcode and a number of operands. The opcode
# determines the instruction format, and the format determines the number of
# operands and the kind of each operand.
class OperandKind(object):
"""
An instance of the `OperandKind` class corresponds to a kind of operand.
Each operand kind has a corresponding type in the Rust representation of an
instruction.
"""
def __init__(self, name, doc):
self.name = name
self.__doc__ = doc
# The camel-cased name of an operand kind is also the Rust type used to
# represent it.
self.camel_name = camel_case(name)
def __str__(self):
return self.name
def __repr__(self):
return 'OperandKind({})'.format(self.name)
def operand_kind(self):
"""
An `OperandKind` instance can be used directly as the type of an
`Operand` when defining an instruction.
"""
return self
def free_typevar(self):
# Return the free typevariable controlling the type of this operand.
return None
#: An SSA value operand. This is a value defined by another instruction.
value = OperandKind(
'value', """
An SSA value defined by another instruction.
This kind of operand can represent any SSA value type, but the
instruction format may restrict the valid value types for a given
operand.
""")
#: A variable-sized list of value operands. Use for Ebb and function call
#: arguments.
variable_args = OperandKind(
'variable_args', """
A variable size list of `value` operands.
Use this to represent arguemtns passed to a function call, arguments
passed to an extended basic block, or a variable number of results
returned from an instruction.
""")
# Instances of immediate operand types are provided in the
# `cretonne.immediates` module.
class ImmediateKind(OperandKind):
"""
The kind of an immediate instruction operand.
"""
def __init__(self, name, doc):
self.name = name
self.__doc__ = doc
def __repr__(self):
return 'ImmediateKind({})'.format(self.name)
# Instances of entity reference operand types are provided in the
# `cretonne.entities` module.
class EntityRefKind(OperandKind):
"""
The kind of an entity reference instruction operand.
"""
def __init__(self, name, doc):
self.name = name
self.__doc__ = doc
def __repr__(self):
return 'EntityRefKind({})'.format(self.name)
# ValueType instances (i8, i32, ...) are provided in the cretonne.types module.
class ValueType(object):
"""
A concrete SSA value type.
All SSA values have a type that is described by an instance of `ValueType`
or one of its subclasses.
"""
# map name -> ValueType.
_registry = dict()
def __init__(self, name, membytes, doc):
self.name = name
self.membytes = membytes
self.__doc__ = doc
assert name not in ValueType._registry
ValueType._registry[name] = self
def __str__(self):
return self.name
def operand_kind(self):
"""
When a `ValueType` object is used to describe the type of an `Operand`
in an instruction definition, the kind of that operand is an SSA value.
"""
return value
def free_typevar(self):
return None
@staticmethod
def by_name(name):
if name in ValueType._registry:
return ValueType._registry[name]
else:
raise AttributeError("No type named '{}'".format(name))
class ScalarType(ValueType):
"""
A concrete scalar (not vector) type.
Also tracks a unique set of :py:class:`VectorType` instances with this type
as the lane type.
"""
def __init__(self, name, membytes, doc):
super(ScalarType, self).__init__(name, membytes, doc)
self._vectors = dict()
def __repr__(self):
return 'ScalarType({})'.format(self.name)
def rust_name(self):
return 'types::' + self.name.upper()
def by(self, lanes):
"""
Get a vector type with this type as the lane type.
For example, ``i32.by(4)`` returns the :obj:`i32x4` type.
"""
if lanes in self._vectors:
return self._vectors[lanes]
else:
v = VectorType(self, lanes)
self._vectors[lanes] = v
return v
class VectorType(ValueType):
"""
A concrete SIMD vector type.
A vector type has a lane type which is an instance of :class:`ScalarType`,
and a positive number of lanes.
"""
def __init__(self, base, lanes):
assert isinstance(base, ScalarType), 'SIMD lanes must be scalar types'
super(VectorType, self).__init__(
name='{}x{}'.format(base.name, lanes),
membytes=lanes*base.membytes,
doc="""
A SIMD vector with {} lanes containing a {} each.
""".format(lanes, base.name))
self.base = base
self.lanes = lanes
def __repr__(self):
return ('VectorType(base={}, lanes={})'
.format(self.base.name, self.lanes))
class IntType(ScalarType):
"""A concrete scalar integer type."""
def __init__(self, bits):
assert bits > 0, 'IntType must have positive number of bits'
super(IntType, self).__init__(
name='i{:d}'.format(bits),
membytes=bits/8,
doc="An integer type with {} bits.".format(bits))
self.bits = bits
def __repr__(self):
return 'IntType(bits={})'.format(self.bits)
class FloatType(ScalarType):
"""A concrete scalar floating point type."""
def __init__(self, bits, doc):
assert bits > 0, 'FloatType must have positive number of bits'
super(FloatType, self).__init__(name='f{:d}'.format(bits),
membytes=bits/8, doc=doc)
self.bits = bits
def __repr__(self):
return 'FloatType(bits={})'.format(self.bits)
class BoolType(ScalarType):
"""A concrete scalar boolean type."""
def __init__(self, bits):
assert bits > 0, 'BoolType must have positive number of bits'
super(BoolType, self).__init__(
name='b{:d}'.format(bits),
membytes=bits/8,
doc="A boolean type with {} bits.".format(bits))
self.bits = bits
def __repr__(self):
return 'BoolType(bits={})'.format(self.bits)
# Parametric polymorphism.
#: A `TypeSet` represents a set of types. We don't allow arbitrary subsets of
#: types, but use a parametrized approach instead.
#: This is represented as a named tuple so it can be used as a dictionary key.
TypeSet = namedtuple(
'TypeSet', [
'allow_scalars',
'allow_simd',
'base',
'all_ints',
'all_floats',
'all_bools'])
class TypeVar(object):
"""
Type variables can be used in place of concrete types when defining
instructions. This makes the instructions *polymorphic*.
A type variable is restricted to vary over a subset of the value types.
This subset is specified by a set of flags that control the permitted base
types and whether the type variable can assume scalar or vector types, or
both.
:param name: Short name of type variable used in instruction descriptions.
:param doc: Documentation string.
:param base: Single base type or list of base types. Use this to specify an
exact set of base types if the general categories below are not good
enough.
:param ints: Allow all integer base types.
:param floats: Allow all floating point base types.
:param bools: Allow all boolean base types.
:param scalars: Allow type variable to assume scalar types.
:param simd: Allow type variable to assume vector types.
"""
def __init__(
self, name, doc, base=None,
ints=False, floats=False, bools=False,
scalars=True, simd=False,
derived_func=None):
self.name = name
self.__doc__ = doc
self.base = base
self.is_derived = isinstance(base, TypeVar)
if self.is_derived:
assert derived_func
self.derived_func = derived_func
self.name = '{}({})'.format(derived_func, base.name)
else:
self.type_set = TypeSet(
allow_scalars=scalars,
allow_simd=simd,
base=base,
all_ints=ints,
all_floats=floats,
all_bools=bools)
def __str__(self):
return "`{}`".format(self.name)
def lane_of(self):
"""
Return a derived type variable that is the scalar lane type of this
type variable.
When this type variable assumes a scalar type, the derived type will be
the same scalar type.
"""
return TypeVar(None, None, base=self, derived_func='LaneOf')
def as_bool(self):
"""
Return a derived type variable that has the same vector geometry as
this type variable, but with boolean lanes. Scalar types map to `b1`.
"""
return TypeVar(None, None, base=self, derived_func='AsBool')
def operand_kind(self):
# When a `TypeVar` object is used to describe the type of an `Operand`
# in an instruction definition, the kind of that operand is an SSA
# value.
return value
def free_typevar(self):
if isinstance(self.base, TypeVar):
return self.base
else:
return self
# Defining instructions.
class InstructionGroup(object):
"""
Every instruction must belong to exactly one instruction group. A given
target architecture can support instructions from multiple groups, and it
does not necessarily support all instructions in a group.
New instructions are automatically added to the currently open instruction
group.
"""
# The currently open instruction group.
_current = None
def open(self):
"""
Open this instruction group such that future new instructions are
added to this group.
"""
assert InstructionGroup._current is None, (
"Can't open {} since {} is already open"
.format(self, InstructionGroup._current))
InstructionGroup._current = self
def close(self):
"""
Close this instruction group. This function should be called before
opening another instruction group.
"""
assert InstructionGroup._current is self, (
"Can't close {}, the open instuction group is {}"
.format(self, InstructionGroup._current))
InstructionGroup._current = None
def __init__(self, name, doc):
self.name = name
self.__doc__ = doc
self.instructions = []
self.open()
@staticmethod
def append(inst):
assert InstructionGroup._current, \
"Open an instruction group before defining instructions."
InstructionGroup._current.instructions.append(inst)
class Operand(object):
"""
An instruction operand can be an *immediate*, an *SSA value*, or an *entity
reference*. The type of the operand is one of:
1. A :py:class:`ValueType` instance indicates an SSA value operand with a
concrete type.
2. A :py:class:`TypeVar` instance indicates an SSA value operand, and the
instruction is polymorphic over the possible concrete types that the
type variable can assume.
3. An :py:class:`ImmediateKind` instance indicates an immediate operand
whose value is encoded in the instruction itself rather than being
passed as an SSA value.
4. An :py:class:`EntityRefKind` instance indicates an operand that
references another entity in the function, typically something declared
in the function preamble.
"""
def __init__(self, name, typ, doc=''):
self.name = name
self.typ = typ
self.__doc__ = doc
self.kind = typ.operand_kind()
def get_doc(self):
if self.__doc__:
return self.__doc__
else:
return self.typ.__doc__
def __str__(self):
return "`{}`".format(self.name)
class InstructionFormat(object):
"""
Every instruction opcode has a corresponding instruction format which
determines the number of operands and their kinds. Instruction formats are
identified structurally, i.e., the format of an instruction is derived from
the kinds of operands used in its declaration.
Most instruction formats produce a single result, or no result at all. If
an instruction can produce more than one result, the `multiple_results`
flag must be set on its format. All results are of the `value` kind, and
the instruction format does not keep track of how many results are
produced. Some instructions, like `call`, may have a variable number of
results.
All instruction formats must be predefined in the
:py:mod:`cretonne.formats` module.
:param kinds: List of `OperandKind` objects describing the operands.
:param name: Instruction format name in CamelCase. This is used as a Rust
variant name in both the `InstructionData` and `InstructionFormat`
enums.
:param multiple_results: Set to `True` if this instruction format allows
more than one result to be produced.
:param boxed_storage: Set to `True` is this instruction format requires a
`data: Box<...>` pointer to additional storage in its `InstructionData`
variant.
:param typevar_operand: Index of the input operand that is used to infer
the controlling type variable. By default, this is the first `value`
operand.
"""
# Map (multiple_results, kind, kind, ...) -> InstructionFormat
_registry = dict()
# All existing formats.
all_formats = list()
def __init__(self, *kinds, **kwargs):
self.name = kwargs.get('name', None)
self.kinds = kinds
self.multiple_results = kwargs.get('multiple_results', False)
self.boxed_storage = kwargs.get('boxed_storage', False)
# Which of self.kinds are `value`?
self.value_operands = tuple(
i for i, k in enumerate(self.kinds) if k is value)
# The typevar_operand argument must point to a 'value' operand.
self.typevar_operand = kwargs.get('typevar_operand', None)
if self.typevar_operand is not None:
assert self.kinds[self.typevar_operand] is value, \
"typevar_operand must indicate a 'value' operand"
elif len(self.value_operands) > 0:
# Default to the first 'value' operand, if there is one.
self.typevar_operand = self.value_operands[0]
# Compute a signature for the global registry.
sig = (self.multiple_results,) + kinds
if sig in InstructionFormat._registry:
raise RuntimeError(
"Format '{}' has the same signature as existing format '{}'"
.format(self.name, InstructionFormat._registry[sig]))
InstructionFormat._registry[sig] = self
InstructionFormat.all_formats.append(self)
@staticmethod
def lookup(ins, outs):
"""
Find an existing instruction format that matches the given lists of
instruction inputs and outputs.
The `ins` and `outs` arguments correspond to the
:py:class:`Instruction` arguments of the same name, except they must be
tuples of :py:`Operand` objects.
"""
multiple_results = len(outs) > 1
sig = (multiple_results,) + tuple(op.kind for op in ins)
if sig not in InstructionFormat._registry:
raise RuntimeError(
"No instruction format matches ins = ({}){}".format(
", ".join(map(str, sig[1:])),
"[multiple results]" if multiple_results else ""))
return InstructionFormat._registry[sig]
@staticmethod
def extract_names(globs):
"""
Given a dict mapping name -> object as returned by `globals()`, find
all the InstructionFormat objects and set their name from the dict key.
This is used to name a bunch of global variables in a module.
"""
for name, obj in globs.iteritems():
if isinstance(obj, InstructionFormat):
assert obj.name is None
obj.name = name
class Instruction(object):
"""
The operands to the instruction are specified as two tuples: ``ins`` and
``outs``. Since the Python singleton tuple syntax is a bit awkward, it is
allowed to specify a singleton as just the operand itself, i.e., `ins=x`
and `ins=(x,)` are both allowed and mean the same thing.
:param name: Instruction mnemonic, also becomes opcode name.
:param doc: Documentation string.
:param ins: Tuple of input operands. This can be a mix of SSA value
operands and other operand kinds.
:param outs: Tuple of output operands. The output operands must be SSA
values or `variable_args`.
:param is_terminator: This is a terminator instruction.
:param is_branch: This is a branch instruction.
"""
def __init__(self, name, doc, ins=(), outs=(), **kwargs):
self.name = name
self.camel_name = camel_case(name)
self.__doc__ = doc
self.ins = self._to_operand_tuple(ins)
self.outs = self._to_operand_tuple(outs)
self.format = InstructionFormat.lookup(self.ins, self.outs)
# Indexes into outs for value results. Others are `variable_args`.
self.value_results = tuple(
i for i, o in enumerate(self.outs) if o.kind is value)
self._verify_polymorphic()
InstructionGroup.append(self)
def _verify_polymorphic(self):
"""
Check if this instruction is polymorphic, and verify its use of type
variables.
"""
poly_ins = [
i for i in self.format.value_operands
if self.ins[i].typ.free_typevar()]
poly_outs = [
i for i, o in enumerate(self.outs)
if o.typ.free_typevar()]
self.is_polymorphic = len(poly_ins) > 0 or len(poly_outs) > 0
if not self.is_polymorphic:
return
# Prefer to use the typevar_operand to infer the controlling typevar.
self.use_typevar_operand = False
typevar_error = None
if self.format.typevar_operand is not None:
try:
tv = self.ins[self.format.typevar_operand].typ
if tv is tv.free_typevar():
self.other_typevars = self._verify_ctrl_typevar(tv)
self.ctrl_typevar = tv
self.use_typevar_operand = True
except RuntimeError as e:
typevar_error = e
if not self.use_typevar_operand:
# The typevar_operand argument doesn't work. Can we infer from the
# first result instead?
if len(self.outs) == 0:
if typevar_error:
raise typevar_error
else:
raise RuntimeError(
"typevar_operand must be a free type variable")
tv = self.outs[0].typ
if tv is not tv.free_typevar():
raise RuntimeError("first result must be a free type variable")
self.other_typevars = self._verify_ctrl_typevar(tv)
self.ctrl_typevar = tv
def _verify_ctrl_typevar(self, ctrl_typevar):
"""
Verify that the use of TypeVars is consistent with `ctrl_typevar` as
the controlling type variable.
All polymorhic inputs must either be derived from `ctrl_typevar` or be
independent free type variables only used once.
All polymorphic results must be derived from `ctrl_typevar`.
Return list of other type variables used, or raise an error.
"""
other_tvs = []
# Check value inputs.
for opidx in self.format.value_operands:
typ = self.ins[opidx].typ
tv = typ.free_typevar()
# Non-polymorphic or derived form ctrl_typevar is OK.
if tv is None or tv is ctrl_typevar:
continue
# No other derived typevars allowed.
if typ is not tv:
raise RuntimeError(
"{}: type variable {} must be derived from {}"
.format(self.ins[opidx], typ.name, ctrl_typevar))
# Other free type variables can only be used once each.
if tv in other_tvs:
raise RuntimeError(
"type variable {} can't be used more than once"
.format(tv.name))
other_tvs.append(tv)
# Check outputs.
for result in self.outs:
typ = result.typ
tv = typ.free_typevar()
# Non-polymorphic or derived from ctrl_typevar is OK.
if tv is None or tv is ctrl_typevar:
continue
raise RuntimeError(
"type variable in output not derived from ctrl_typevar")
return other_tvs
@staticmethod
def _to_operand_tuple(x):
# Allow a single Operand instance instead of the awkward singleton
# tuple syntax.
if isinstance(x, Operand):
x = (x,)
else:
x = tuple(x)
for op in x:
assert isinstance(op, Operand)
return x
def bind(self, *args):
"""
Bind a polymorphic instruction to a concrete list of type variable
values.
"""
assert self.is_polymorphic
return BoundInstruction(self, args)
def __getattr__(self, name):
"""
Bind a polymorphic instruction to a single type variable with dot
syntax:
>>> iadd.i32
"""
return self.bind(ValueType.by_name(name))
def fully_bound(self):
"""
Verify that all typevars have been bound, and return a
`(inst, typevars)` pair.
This version in `Instruction` itself allows non-polymorphic
instructions to duck-type as `BoundInstruction`\s.
"""
assert not self.is_polymorphic, self
return (self, ())
class BoundInstruction(object):
"""
A polymorphic `Instruction` bound to concrete type variables.
"""
def __init__(self, inst, typevars):
self.inst = inst
self.typevars = typevars
assert len(typevars) <= 1 + len(inst.other_typevars)
def __str__(self):
return '.'.join([self.inst.name, ] + map(str, self.typevars))
def bind(self, *args):
"""
Bind additional typevars.
"""
return BoundInstruction(self.inst, self.typevars + args)
def __getattr__(self, name):
"""
Bind an additional typevar dot syntax:
>>> uext.i32.i8
"""
return self.bind(ValueType.by_name(name))
def fully_bound(self):
"""
Verify that all typevars have been bound, and return a
`(inst, typevars)` pair.
"""
if len(self.typevars) < 1 + len(self.inst.other_typevars):
unb = ', '.join(
str(tv) for tv in
self.inst.other_typevars[len(self.typevars) - 1:])
raise AssertionError("Unbound typevar {} in {}".format(unb, self))
assert len(self.typevars) == 1 + len(self.inst.other_typevars)
return (self.inst, self.typevars)
# Defining target ISAs.
class TargetISA(object):
"""
A target instruction set architecture.
The `TargetISA` class collects everything known about a target ISA.
:param name: Short mnemonic name for the ISA.
:param instruction_groups: List of `InstructionGroup` instances that are
relevant for this ISA.
"""
def __init__(self, name, instrution_groups):
self.name = name
self.settings = None
self.instruction_groups = instrution_groups
class CPUMode(object):
"""
A CPU mode determines which instruction encodings are active.
All instruction encodings are associated with exactly one `CPUMode`, and
all CPU modes are associated with exactly one `TargetISA`.
:param name: Short mnemonic name for the CPU mode.
:param target: Associated `TargetISA`.
"""
def __init__(self, name, isa):
self.name = name
self.isa = isa
self.encodings = []
def enc(self, *args, **kwargs):
"""
Add a new encoding to this CPU mode.
Arguments are the `Encoding constructor arguments, except for the first
`CPUMode argument which is implied.
"""
self.encodings.append(Encoding(self, *args, **kwargs))
class EncRecipe(object):
"""
A recipe for encoding instructions with a given format.
Many different instructions can be encoded by the same recipe, but they
must all have the same instruction format.
:param name: Short mnemonic name for this recipe.
:param format: All encoded instructions must have this
:py:class:`InstructionFormat`.
"""
def __init__(self, name, format):
self.name = name
self.format = format
class Encoding(object):
"""
Encoding for a concrete instruction.
An `Encoding` object ties an instruction opcode with concrete type
variables together with and encoding recipe and encoding bits.
:param cpumode: The CPU mode where the encoding is active.
:param inst: The :py:class:`Instruction` or :py:class:`BoundInstruction`
being encoded.
:param recipe: The :py:class:`EncRecipe` to use.
:param encbits: Additional encoding bits to be interpreted by `recipe`.
"""
def __init__(self, cpumode, inst, recipe, encbits):
assert isinstance(cpumode, CPUMode)
assert isinstance(recipe, EncRecipe)
self.inst, self.typevars = inst.fully_bound()
self.cpumode = cpumode
assert self.inst.format == recipe.format, (
"Format {} must match recipe: {}".format(
self.inst.format, recipe.format))
self.recipe = recipe
self.encbits = encbits
@staticmethod
def _to_type_tuple(x):
# Allow a single ValueType instance instead of the awkward singleton
# tuple syntax.
if isinstance(x, ValueType):
x = (x,)
else:
x = tuple(x)
for ty in x:
assert isinstance(ty, ValueType)
return x
# Import the fixed instruction formats now so they can be added to the
# registry.
importlib.import_module('cretonne.formats')