Rename the 'cretonne' crate to 'cretonne-codegen'.

This fixes the next part of #287.

lib/codegen/meta/semantics/macros.py

@@ -0,0 +1,45 @@
+"""
+Useful semantics "macro" instructions built on top of
+the primitives.
+"""
+from __future__ import absolute_import
+from cdsl.operands import Operand
+from cdsl.typevar import TypeVar
+from cdsl.instructions import Instruction, InstructionGroup
+from base.types import b1
+from base.immediates import imm64
+from cdsl.ast import Var
+from cdsl.xform import Rtl
+from semantics.primitives import bv_from_imm64, bvite
+import base.formats # noqa
+
+GROUP = InstructionGroup("primitive_macros", "Semantic macros instruction set")
+AnyBV = TypeVar('AnyBV', bitvecs=True, doc="")
+x = Var('x')
+y = Var('y')
+imm = Var('imm')
+a = Var('a')
+
+#
+# Bool-to-bv1
+#
+BV1 = TypeVar("BV1", bitvecs=(1, 1), doc="")
+bv1_op = Operand('bv1_op', BV1, doc="")
+cond_op = Operand("cond", b1, doc="")
+bool2bv = Instruction(
+        'bool2bv', r"""Convert a b1 value to a 1-bit BV""",
+        ins=cond_op, outs=bv1_op)
+
+v1 = Var('v1')
+v2 = Var('v2')
+bvone = Var('bvone')
+bvzero = Var('bvzero')
+bool2bv.set_semantics(
+        v1 << bool2bv(v2),
+        Rtl(
+            bvone << bv_from_imm64(imm64(1)),
+            bvzero << bv_from_imm64(imm64(0)),
+            v1 << bvite(v2, bvone, bvzero)
+        ))
+
+GROUP.close()