Begin defining the meta language.

The Cretonne meta language is used to describe Cretonne instructions, both the
target independent ones in the base instruction set and real target
instructions.

Start by providing type definitions matching langref, and begin the meta
language reference using autodoc to pull in the PYthon definitions.

meta/cretonne/__init__.py

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+"""
+Cretonne meta language module.
+
+This module provides classes and functions used to describe Cretonne
+instructions.
+"""
+
+# Concrete types.
+#
+# Instances (i8, i32, ...) are provided in the cretonne.types module.
+
+class Type(object):
+    """A concrete value type."""
+
+    def __str__(self):
+        return self.name
+
+class ScalarType(Type):
+    """
+    A concrete scalar (not vector) type.
+
+    Also tracks a unique set of :class:`VectorType` instances with this type as
+    the lane type.
+    """
+
+    def __init__(self, name):
+        self.name = name
+        self._vectors = dict()
+
+    def __repr__(self):
+        return 'ScalarType({})'.format(self.name)
+
+    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(Type):
+    """
+    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'
+        self.base = base
+        self.lanes = lanes
+        self.name = '{}x{}'.format(base.name, 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__('i{:d}'.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):
+        assert bits > 0, 'FloatType must have positive number of bits'
+        super(FloatType, self).__init__('f{:d}'.format(bits))
+        self.bits = bits
+
+    def __repr__(self):
+        return 'FloatType(bits={})'.format(self.bits)

meta/cretonne/types.py

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+"""Predefined types."""
+
+from . import ScalarType, IntType, FloatType
+
+#: A boolean value.
+bool = ScalarType('bool')
+
+i8  = IntType(8)  #: 8-bit int.
+i16 = IntType(16) #: 16-bit int.
+i32 = IntType(32) #: 32-bit int.
+i64 = IntType(64) #: 64-bit int.
+
+f32 = FloatType(32) #: IEEE 32-bit float.
+f64 = FloatType(64) #: IEEE 64-bit float
+
+i8x16 = i8.by(16) #: Vector of 16 i8 lanes.
+
+f32x4 = f32.by(4) #: Vector of 4 f32 lanes.
+f64x2 = f64.by(2) #: Vector of 2 f64 lanes.
+