Define AST nodes and instruction transformations.

Enable syntax: iadd(x, y) which creates an Apply node.
Enable syntax: z << iadd(x, y) which creates a Def node.

Add an XForm class which represents source and destination patterns as
RTL lists.

meta/cretonne/test_xform.py

@@ -0,0 +1,59 @@
+from __future__ import absolute_import
+from unittest import TestCase
+from doctest import DocTestSuite
+from . import xform
+from .base import iadd, iadd_imm, iconst
+from .ast import Var
+from .xform import Rtl, XForm
+
+
+def load_tests(loader, tests, ignore):
+    tests.addTests(DocTestSuite(xform))
+    return tests
+
+
+x = Var('x')
+y = Var('y')
+a = Var('a')
+c = Var('c')
+
+
+class TestXForm(TestCase):
+    def test_macro_pattern(self):
+        src = Rtl(a << iadd_imm(x, y))
+        dst = Rtl(
+                c << iconst(y),
+                a << iadd(x, c))
+        XForm(src, dst)
+
+    def test_def_input(self):
+        # Src pattern has a def which is an input in dst.
+        src = Rtl(a << iadd_imm(x, 1))
+        dst = Rtl(y << iadd_imm(a, 1))
+        with self.assertRaisesRegexp(
+                AssertionError,
+                "'a' used as both input and def"):
+            XForm(src, dst)
+
+    def test_input_def(self):
+        # Converse of the above.
+        src = Rtl(y << iadd_imm(a, 1))
+        dst = Rtl(a << iadd_imm(x, 1))
+        with self.assertRaisesRegexp(
+                AssertionError,
+                "'a' used as both input and def"):
+            XForm(src, dst)
+
+    def test_extra_input(self):
+        src = Rtl(a << iadd_imm(x, 1))
+        dst = Rtl(a << iadd(x, y))
+        with self.assertRaisesRegexp(AssertionError, "extra inputs in dst"):
+            XForm(src, dst)
+
+    def test_double_def(self):
+        src = Rtl(
+                a << iadd_imm(x, 1),
+                a << iadd(x, y))
+        dst = Rtl(a << iadd(x, y))
+        with self.assertRaisesRegexp(AssertionError, "'a' multiply defined"):
+            XForm(src, dst)