# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1315679370 -7200
# Node ID 835c936bfd461b66dd3be47ee17352c336686e9b
# Parent  b79edd6601da5ae85085db4ac05ae21071f2fc98
Fixed vacuuming to avoid removing objects referenced by more than one name in a
namespace.
Changed the strict constant check on attributes to permit Constant subclasses.
Extended the no-operation test to check for load operations immediately after
store operations.
Removed the active value instruction properly when requested.
Improved docstrings and instruction string representations.

diff -r b79edd6601da -r 835c936bfd46 micropython/common.py
--- a/micropython/common.py	Thu Sep 08 00:33:33 2011 +0200
+++ b/micropython/common.py	Sat Sep 10 20:29:30 2011 +0200
@@ -264,7 +264,8 @@
     """
     Return for the given attribute 'usage', using the 'objtable', the object
     types which satisfy such usage, reporting any problems for the given 'name'
-    and 'unit_name'.
+    and 'unit_name'. Each object type is given as a tuple of the form (type,
+    is_static).
     """
 
     all_objtypes = set()
diff -r b79edd6601da -r 835c936bfd46 micropython/data.py
--- a/micropython/data.py	Thu Sep 08 00:33:33 2011 +0200
+++ b/micropython/data.py	Sat Sep 10 20:29:30 2011 +0200
@@ -977,7 +977,7 @@
         """
 
         value = self.get_value()
-        return not (value is None or isinstance(value, Instance))
+        return not (value is None or (isinstance(value, Instance) and not isinstance(value, Constant)))
 
     def is_static_attribute(self):
 
diff -r b79edd6601da -r 835c936bfd46 micropython/inspect.py
--- a/micropython/inspect.py	Thu Sep 08 00:33:33 2011 +0200
+++ b/micropython/inspect.py	Sat Sep 10 20:29:30 2011 +0200
@@ -194,6 +194,24 @@
 
         "Vacuum the given object 'obj'."
 
+        # Get all constant objects in apparent use.
+
+        if delete_all:
+            obj_objects = set()
+        else:
+            obj_objects = []
+            for name, attr in obj.items_for_vacuum():
+
+                # Get constant objects for attributes in use.
+
+                if self.importer.uses_attribute(obj.full_name(), name) and \
+                    attr is not None and attr.is_constant():
+
+                    value = attr.get_value()
+                    obj_objects.append(value)
+
+        # Now vacuum unused attributes and objects not in use.
+
         for name, attr in obj.items_for_vacuum():
 
             # Only consider deleting entire unused objects or things accessible
@@ -206,12 +224,15 @@
                 # have been defined within the object and therefore are not
                 # redefined by other code regions.
 
-                if attr is not None and attr.assignments == 1:
+                if attr is not None and attr.is_constant():
                     value = attr.get_value()
 
                     # The value must have this object as a parent.
+                    # However, it must not be shared by several names.
 
-                    if value is not obj and value.parent is obj and value in self.all_objects:
+                    if value is not obj and value.parent is obj and \
+                        value in self.all_objects and value not in obj_objects:
+
                         self.all_objects.remove(value)
 
                         # Delete class contents and lambdas from functions.
@@ -462,6 +483,11 @@
 
     def _visitAttr(self, expr, attrname, node):
 
+        """
+        Process the attribute provided by the given 'expr' with the given
+        'attrname' and involving the given 'node'.
+        """
+
         # Attempt to identify the nature of the attribute.
 
         if isinstance(expr, Attr):
diff -r b79edd6601da -r 835c936bfd46 micropython/opt.py
--- a/micropython/opt.py	Thu Sep 08 00:33:33 2011 +0200
+++ b/micropython/opt.py	Sat Sep 10 20:29:30 2011 +0200
@@ -137,8 +137,8 @@
         """
 
         if self.active in self.active_values:
-            removed = self.active
-            self.translation.remove_op()
+            removed = self.translation.remove_op()
+            self.active_values.remove(removed)
             return removed
         else:
             return None
@@ -239,7 +239,8 @@
         # NOTE: locals/frames.
 
         return isinstance(instruction, (StoreAddress, StoreAddressContext)) and \
-            instruction.attr.assignments == 1
+            instruction.attr.is_constant() and \
+            instruction.attr.is_strict_constant()
 
     def is_simple_input(self, instruction):
 
@@ -263,8 +264,11 @@
         last_op = last_op or self.translation.last_op()
         return last_op and last_op.attr == instruction.attr and (
             isinstance(instruction, StoreTemp) and isinstance(last_op, LoadTemp) or
-            isinstance(instruction, StoreAddress) and isinstance(last_op, LoadAddress)
-            )
+            isinstance(instruction, StoreAddress) and isinstance(last_op, LoadAddress) or
+            last_op.source == instruction.target and (
+                isinstance(instruction, LoadTemp) and isinstance(last_op, StoreTemp) or
+                isinstance(instruction, LoadAddress) and isinstance(last_op, StoreAddress)
+            ))
 
     # Convenience tests on outputs.
 
@@ -335,7 +339,7 @@
 
     # Optimisation methods. See the supported_optimisations class attribute.
 
-    def optimise_constant_storage(self, expr=None):
+    def optimise_constant_storage(self, expr):
 
         """
         Where the last operation stores a constant into a target which is also
diff -r b79edd6601da -r 835c936bfd46 micropython/rsvp.py
--- a/micropython/rsvp.py	Thu Sep 08 00:33:33 2011 +0200
+++ b/micropython/rsvp.py	Sat Sep 10 20:29:30 2011 +0200
@@ -334,7 +334,7 @@
 
     def format_operand(self):
         operand = self.get_operand()
-        return repr(operand)
+        return operand is not None and repr(operand) or ""
 
     def format_working(self):
         return self.working != self.default_working and (", working=%r" % self.working) or ""