--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/python/target/instructionselector.py	Sun Nov 24 11:24:15 2013 +0100
@@ -0,0 +1,59 @@
+import ir
+import irmach
+from irmach import AbstractInstruction as makeIns
+import target
+
+def genTemps():
+    n = 900
+    while True:
+        yield ir.Temp('t{}'.format(n))
+        n = n + 1
+
+
+class InstructionSelector:
+    """
+        Base instruction selector. This class must be overridden by
+        backends.
+    """
+    def __init__(self):
+        self.temps = genTemps()
+
+    def newTmp(self):
+        return self.temps.__next__()
+
+    def munchFunction(self, f, frame):
+        # Entry point for instruction selection
+        assert isinstance(f, ir.Function)
+        self.targets = {}
+        # Enter a frame per function:
+        self.frame = frame
+        # First define labels:
+        for bb in f.Blocks:
+            itgt = makeIns(target.Label(bb.name))
+            self.targets[bb] = itgt
+        # Generate code for all blocks:
+        for bb in f.Blocks:
+            self.emit2(self.targets[bb])
+            for i in bb.Instructions:
+                self.munchStm(i)
+        self.munchStm(ir.Move(self.frame.rv, f.return_value))
+
+    def move(self, dst, src):
+        raise NotImplementedError('Not target implemented')
+
+    def emit(self, *args, **kwargs):
+        """ Abstract instruction emitter """
+        i = makeIns(*args, **kwargs)
+        return self.emit2(i)
+
+    def emit2(self, i):
+        self.frame.instructions.append(i)
+        return i
+
+    def munchStm(self, s):
+        """ Implement this in the target specific back-end """
+        raise NotImplementedError()
+
+    def munchExpr(self, e):
+        """ Implement this in the target specific back-end """
+        raise NotImplementedError()