--- a/python/ir/instruction.py	Mon Jul 29 20:23:13 2013 +0200
+++ b/python/ir/instruction.py	Tue Jul 30 17:57:46 2013 +0200
@@ -14,9 +14,17 @@
         return '{0}'.format(self.name) # + str(self.IsUsed)
 
     @property
+    def UsedInBlocks(self):
+        bbs = [i.parent for i in self.used_by + [self.Setter]]
+        assert all(isinstance(bb, BasicBlock) for bb in bbs)
+        return set(bbs)
+
+    @property
     def IsUsed(self):
         return len(self.used_by) > 0
 
+    Used = IsUsed
+
     def onlyUsedInBlock(self, bb):
         for use in self.used_by:
             ins = use
@@ -85,24 +93,32 @@
     Parent = property(getParent, setParent)
 
     def replaceValue(self, old, new):
-        raise NotImplementedError()
+        raise NotImplementedError('{}'.format(type(self)))
 
     @property
     def Position(self):
         return self.parent.Instructions.index(self)
 
+    @property
+    def Function(self):
+        return self.Block.parent
+
+    @property
+    def Block(self):
+        return self.Parent
+
     def check(self):
         # Check that the variables defined by this instruction 
         # are only used in the same block
         for v in self.defs:
             assert v.Setter is self
             for ub in v.used_by:
-                assert ub.parent == self.parent
+                assert ub.Function == self.Function
 
         # Check that variables used are defined earlier:
         for u in self.uses:
             v = u.val
-            assert self.Position > v.Setter.Position
+            #assert self.Position > v.Setter.Position
 
 
 
@@ -206,19 +222,20 @@
 
 # Memory functions:
 class Load(Instruction):
-   def __init__(self, location, value):
-      super().__init__()
-      assert type(value) is Value
-      assert isinstance(location, Value), "Location must be a value"
-      self.value = value
-      self.addDef(value)
-      self.location = location
-      self.addUse(self.location)
-   def __repr__(self):
-      return '{} = [{}]'.format(self.value, self.location)
+    def __init__(self, location, value):
+        super().__init__()
+        assert type(value) is Value
+        assert isinstance(location, Value), "Location must be a value"
+        self.value = value
+        self.addDef(value)
+        self.location = location
+        self.addUse(self.location)
+
+    def __repr__(self):
+        return '{} = [{}]'.format(self.value, self.location)
 
 class Store(Instruction):
-   def __init__(self, location, value):
+    def __init__(self, location, value):
       super().__init__()
       assert type(value) is Value, value
       assert isinstance(location, Value), "Location must be a value"
@@ -226,8 +243,19 @@
       self.value = value
       self.addUse(value)
       self.addUse(location)
-   def __repr__(self):
-      return '[{}] = {}'.format(self.location, self.value)
+    
+    def __repr__(self):
+        return '[{}] = {}'.format(self.location, self.value)
+
+    def replaceValue(self, old, new):
+        if old is self.value:
+            self.value = new
+        elif old is self.location:
+            self.location = new
+        else:
+            raise Exception()
+        self.removeUse(old)
+        self.addUse(new)
 
 # Branching:
 class Branch(Terminator):
@@ -270,9 +298,10 @@
          self.lab2 = tto
 
 class PhiNode(Instruction):
-   def __init__(self):
-      super().__init__()
-      self.incBB = []
-   def addIncoming(self, bb):
-      self.incBB.append(bb)
+    def __init__(self):
+        super().__init__()
+        self.incBB = []
 
+    def addIncoming(self, bb):
+        self.incBB.append(bb)
+