74625a9b79
Also introduce the concept of a derived type variable, and provide two methods for deriving type vars: lane() and as_bool().
480 lines
15 KiB
Python
480 lines
15 KiB
Python
"""
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Cretonne meta language module.
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This module provides classes and functions used to describe Cretonne
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instructions.
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"""
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import re
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import importlib
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camel_re = re.compile('(^|_)([a-z])')
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def camel_case(s):
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"""Convert the string s to CamelCase"""
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return camel_re.sub(lambda m: m.group(2).upper(), s)
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# Kinds of operands.
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#
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# Each instruction has an opcode and a number of operands. The opcode
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# determines the instruction format, and the format determines the number of
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# operands and the kind of each operand.
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class OperandKind(object):
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"""
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An instance of the `OperandKind` class corresponds to a kind of operand.
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Each operand kind has a corresponding type in the Rust representation of an
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instruction.
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"""
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def __init__(self, name, doc):
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self.name = name
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self.__doc__ = doc
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# The camel-cased name of an operand kind is also the Rust type used to
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# represent it.
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self.camel_name = camel_case(name)
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def __str__(self):
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return self.name
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def __repr__(self):
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return 'OperandKind({})'.format(self.name)
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#: An SSA value operand. This is a value defined by another instruction.
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value = OperandKind(
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'value', """
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An SSA value defined by another instruction.
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This kind of operand can represent any SSA value type, but the
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instruction format may restrict the valid value types for a given
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operand.
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""")
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#: A variable-sized list of value operands. Use for Ebb and function call
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#: arguments.
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args = OperandKind(
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'args', """
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A variable size list of `value` operands.
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Use this to represent arguemtns passed to a function call, arguments
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passed to an extended basic block, or a variable number of results
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returned from an instruction.
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""")
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# Instances of immediate operand types are provided in the cretonne.immediates
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# module.
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class ImmediateKind(OperandKind):
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"""
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The kind of an immediate instruction operand.
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"""
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def __init__(self, name, doc):
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self.name = name
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self.__doc__ = doc
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def __repr__(self):
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return 'ImmediateKind({})'.format(self.name)
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def operand_kind(self):
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"""
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An `ImmediateKind` instance can be used directly as the type of an
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`Operand` when defining an instruction.
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"""
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return self
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# ValueType instances (i8, i32, ...) are provided in the cretonne.types module.
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class ValueType(object):
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"""
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A concrete SSA value type.
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All SSA values have a type that is described by an instance of `ValueType`
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or one of its subclasses.
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"""
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def __init__(self, name, membytes, doc):
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self.name = name
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self.membytes = membytes
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self.__doc__ = doc
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def __str__(self):
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return self.name
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def operand_kind(self):
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"""
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When a `ValueType` object is used to describe the type of an `Operand`
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in an instruction definition, the kind of that operand is an SSA value.
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"""
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return value
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class ScalarType(ValueType):
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"""
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A concrete scalar (not vector) type.
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Also tracks a unique set of :py:class:`VectorType` instances with this type
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as the lane type.
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"""
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def __init__(self, name, membytes, doc):
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super(ScalarType, self).__init__(name, membytes, doc)
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self._vectors = dict()
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def __repr__(self):
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return 'ScalarType({})'.format(self.name)
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def by(self, lanes):
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"""
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Get a vector type with this type as the lane type.
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For example, ``i32.by(4)`` returns the :obj:`i32x4` type.
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"""
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if lanes in self._vectors:
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return self._vectors[lanes]
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else:
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v = VectorType(self, lanes)
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self._vectors[lanes] = v
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return v
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class VectorType(ValueType):
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"""
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A concrete SIMD vector type.
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A vector type has a lane type which is an instance of :class:`ScalarType`,
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and a positive number of lanes.
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"""
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def __init__(self, base, lanes):
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assert isinstance(base, ScalarType), 'SIMD lanes must be scalar types'
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super(VectorType, self).__init__(
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name='{}x{}'.format(base.name, lanes),
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membytes=lanes*base.membytes,
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doc="""
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A SIMD vector with {} lanes containing a {} each.
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""".format(lanes, base.name))
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self.base = base
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self.lanes = lanes
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def __repr__(self):
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return ('VectorType(base={}, lanes={})'
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.format(self.base.name, self.lanes))
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class IntType(ScalarType):
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"""A concrete scalar integer type."""
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def __init__(self, bits):
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assert bits > 0, 'IntType must have positive number of bits'
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super(IntType, self).__init__(
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name='i{:d}'.format(bits),
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membytes=bits/8,
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doc="An integer type with {} bits.".format(bits))
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self.bits = bits
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def __repr__(self):
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return 'IntType(bits={})'.format(self.bits)
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class FloatType(ScalarType):
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"""A concrete scalar floating point type."""
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def __init__(self, bits, doc):
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assert bits > 0, 'FloatType must have positive number of bits'
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super(FloatType, self).__init__(name='f{:d}'.format(bits),
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membytes=bits/8, doc=doc)
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self.bits = bits
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def __repr__(self):
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return 'FloatType(bits={})'.format(self.bits)
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class BoolType(ScalarType):
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"""A concrete scalar boolean type."""
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def __init__(self, bits):
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assert bits > 0, 'BoolType must have positive number of bits'
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super(BoolType, self).__init__(
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name='b{:d}'.format(bits),
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membytes=bits/8,
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doc="A boolean type with {} bits.".format(bits))
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self.bits = bits
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def __repr__(self):
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return 'BoolType(bits={})'.format(self.bits)
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# Parametric polymorphism.
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class TypeVar(object):
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"""
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Type variables can be used in place of concrete types when defining
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instructions. This makes the instructions *polymorphic*.
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A type variable is restricted to vary over a subset of the value types.
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This subset is specified by a set of flags that control the permitted base
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types and whether the type variable can assume scalar or vector types, or
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both.
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:param name: Short name of type variable used in instruction descriptions.
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:param doc: Documentation string.
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:param base: Single base type or list of base types. Use this to specify an
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exact set of base types if the general categories below are not good
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enough.
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:param ints: Allow all integer base types.
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:param floats: Allow all floating point base types.
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:param bools: Allow all boolean base types.
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:param scalars: Allow type variable to assume scalar types.
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:param simd: Allow type variable to assume vector types.
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"""
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def __init__(
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self, name, doc, base=None,
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ints=False, floats=False, bools=False,
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scalars=True, simd=False):
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self.name = name
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self.__doc__ = doc
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def lane(self):
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"""
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Return a derived type variable that is the scalar lane type of this
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type variable.
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When this type variable assumes a scalar type, the derived type will be
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the same scalar type.
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"""
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return TypeVar("Lane type of " + self.name, '', base=self, simd=False)
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def as_bool(self):
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"""
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Return a derived type variable that has the same vector geometry as
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this type variable, but with boolean lanes. Scalar types map to `b1`.
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"""
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return TypeVar(self.name + " as boolean", '', base=self, bools=True)
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def operand_kind(self):
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# When a `TypeVar` object is used to describe the type of an `Operand`
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# in an instruction definition, the kind of that operand is an SSA
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# value.
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return value
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# Defining instructions.
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class InstructionGroup(object):
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"""
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Every instruction must belong to exactly one instruction group. A given
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target architecture can support instructions from multiple groups, and it
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does not necessarily support all instructions in a group.
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New instructions are automatically added to the currently open instruction
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group.
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"""
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# The currently open instruction group.
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_current = None
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def open(self):
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"""
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Open this instruction group such that future new instructions are
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added to this group.
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"""
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assert InstructionGroup._current is None, (
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"Can't open {} since {} is already open"
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.format(self, InstructionGroup._current))
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InstructionGroup._current = self
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def close(self):
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"""
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Close this instruction group. This function should be called before
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opening another instruction group.
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"""
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assert InstructionGroup._current is self, (
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"Can't close {}, the open instuction group is {}"
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.format(self, InstructionGroup._current))
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InstructionGroup._current = None
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def __init__(self, name, doc):
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self.name = name
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self.__doc__ = doc
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self.instructions = []
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self.open()
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@staticmethod
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def append(inst):
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assert InstructionGroup._current, \
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"Open an instruction group before defining instructions."
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InstructionGroup._current.instructions.append(inst)
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class Operand(object):
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"""
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An instruction operand can be either an *immediate* or an *SSA value*. The
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type of the operand is one of:
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1. A :py:class:`ValueType` instance indicates an SSA value operand with a
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concrete type.
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2. A :py:class:`TypeVar` instance indicates an SSA value operand, and the
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instruction is polymorphic over the possible concrete types that the
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type variable can assume.
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3. An :py:class:`ImmediateKind` instance indicates an immediate operand
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whose value is encoded in the instruction itself rather than being
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passed as an SSA value.
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"""
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def __init__(self, name, typ, doc=''):
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self.name = name
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self.typ = typ
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self.__doc__ = doc
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self.kind = typ.operand_kind()
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def get_doc(self):
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if self.__doc__:
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return self.__doc__
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else:
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return self.typ.__doc__
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class InstructionFormat(object):
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"""
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Every instruction opcode has a corresponding instruction format which
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determines the number of operands and their kinds. Instruction formats are
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identified structurally, i.e., the format of an instruction is derived from
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the kinds of operands used in its declaration.
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Most instruction formats produce a single result, or no result at all. If
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an instruction can produce more than one result, the `multiple_results`
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flag must be set on its format. All results are of the `value` kind, and
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the instruction format does not keep track of how many results are
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produced. Some instructions, like `call`, may have a variable number of
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results.
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All instruction formats must be predefined in the
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:py:mod:`cretonne.formats` module.
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:param kinds: List of `OperandKind` objects describing the operands.
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:param name: Instruction format name in CamelCase. This is used as a Rust
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variant name in both the `InstructionData` and `InstructionFormat`
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enums.
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:param multiple_results: Set to `True` if this instruction format allows
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more than one result to be produced.
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"""
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# Map (multiple_results, kind, kind, ...) -> InstructionFormat
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_registry = dict()
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# All existing formats.
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all_formats = list()
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def __init__(self, *kinds, **kwargs):
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self.name = kwargs.get('name', None)
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self.kinds = kinds
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self.multiple_results = kwargs.get('multiple_results', False)
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# Compute a signature for the global registry.
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sig = (self.multiple_results,) + kinds
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if sig in InstructionFormat._registry:
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raise RuntimeError(
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"Format '{}' has the same signature as existing format '{}'"
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.format(self.name, InstructionFormat._registry[sig]))
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InstructionFormat._registry[sig] = self
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InstructionFormat.all_formats.append(self)
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@staticmethod
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def lookup(ins, outs):
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"""
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Find an existing instruction format that matches the given lists of
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instruction inputs and outputs.
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The `ins` and `outs` arguments correspond to the
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:py:class:`Instruction` arguments of the same name, except they must be
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tuples of :py:`Operand` objects.
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"""
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multiple_results = len(outs) > 1
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sig = (multiple_results,) + tuple(op.kind for op in ins)
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if sig not in InstructionFormat._registry:
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raise RuntimeError(
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"No instruction format matches ins = ({}){}".format(
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", ".join(map(str, sig[1:])),
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"[multiple results]" if multiple_results else ""))
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return InstructionFormat._registry[sig]
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@staticmethod
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def extract_names(globs):
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"""
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Given a dict mapping name -> object as returned by `globals()`, find
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all the InstructionFormat objects and set their name from the dict key.
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This is used to name a bunch of global variables in a module.
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"""
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for name, obj in globs.iteritems():
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if isinstance(obj, InstructionFormat):
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assert obj.name is None
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obj.name = name
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class Instruction(object):
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"""
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The operands to the instruction are specified as two tuples: ``ins`` and
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``outs``. Since the Python singleton tuple syntax is a bit awkward, it is
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allowed to specify a singleton as just the operand itself, i.e., `ins=x`
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and `ins=(x,)` are both allowed and mean the same thing.
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:param name: Instruction mnemonic, also becomes opcode name.
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:param doc: Documentation string.
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:param ins: Tuple of input operands. This can be a mix of SSA value
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operands and immediate operands.
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:param outs: Tuple of output operands. The output operands can't be
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immediates.
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"""
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def __init__(self, name, doc, ins=(), outs=(), **kwargs):
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self.name = name
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self.camel_name = camel_case(name)
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self.__doc__ = doc
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self.ins = self._to_operand_tuple(ins)
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self.outs = self._to_operand_tuple(outs)
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self.format = InstructionFormat.lookup(self.ins, self.outs)
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InstructionGroup.append(self)
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@staticmethod
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def _to_operand_tuple(x):
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# Allow a single Operand instance instead of the awkward singleton
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# tuple syntax.
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if isinstance(x, Operand):
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x = (x,)
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else:
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x = tuple(x)
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for op in x:
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assert isinstance(op, Operand)
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return x
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# Defining targets
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class Target(object):
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"""
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A target instruction set architecture.
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The `Target` class collects everything known about a target ISA.
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:param name: Short mnemonic name for the ISA.
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:param instruction_groups: List of `InstructionGroup` instances that are
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relevant for this ISA.
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"""
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def __init__(self, name, instrution_groups):
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self.name = name
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self.instruction_groups = instrution_groups
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# Import the fixed instruction formats now so they can be added to the
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# registry.
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importlib.import_module('cretonne.formats')
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