Merge pull request #1719 from tjb900/generalised_msf

Generalised MatrixSparseTimeFunction

devito/ir/equations/algorithms.py

@@ -6,7 +6,7 @@
 from devito.symbolics import (retrieve_functions, retrieve_indexed, split_affine,
                               uxreplace)
 from devito.tools import PartialOrderTuple, filter_sorted, flatten, as_tuple
-from devito.types import Dimension, Eq
+from devito.types import Dimension, Eq, IgnoreDimSort
 
 __all__ = ['dimension_sort', 'generate_implicit_exprs', 'lower_exprs']
 
@@ -36,7 +36,10 @@ def handle_indexed(indexed):
                                      if isinstance(d, Dimension)])
         return tuple(relation)
 
-    relations = {handle_indexed(i) for i in retrieve_indexed(expr)}
+    if isinstance(expr.implicit_dims, IgnoreDimSort):
+        relations = set()
+    else:
+        relations = {handle_indexed(i) for i in retrieve_indexed(expr)}
 
     # Add in any implicit dimension (typical of scalar temporaries, or Step)
     relations.add(expr.implicit_dims)

devito/passes/clusters/cse.py

@@ -8,13 +8,17 @@
 __all__ = ['cse']
 
 
+class Temp(Symbol):
+    pass
+
+
 @cluster_pass
 def cse(cluster, sregistry, *args):
     """
     Common sub-expressions elimination (CSE).
     """
-    make = lambda: Symbol(name=sregistry.make_name(), dtype=cluster.dtype).indexify()
-    processed = _cse(cluster.exprs, make)
+    make = lambda: Temp(name=sregistry.make_name(), dtype=cluster.dtype).indexify()
+    processed = _cse(cluster, make)
 
     return cluster.rebuild(processed)
 
@@ -108,9 +112,12 @@ def _compact_temporaries(exprs):
     # First of all, convert to SSA
     exprs = makeit_ssa(exprs)
 
-    # What's gonna be dropped
+    # Drop candidates are all exprs in the form `t0 = s` where `s` is a symbol
+    # Note: only CSE-captured Temps, which are by construction local objects, may
+    # safely be compacted; a generic Symbol could instead be accessed in a subsequent
+    # Cluster, for example: `for (i = ...) { a = b; for (j = a ...) ...`
     mapper = {e.lhs: e.rhs for e in exprs
-              if e.lhs.is_Symbol and (q_leaf(e.rhs) or e.rhs.is_Function)}
+              if isinstance(e.lhs, Temp) and (q_leaf(e.rhs) or e.rhs.is_Function)}
 
     processed = []
     for e in exprs:

devito/tools/utils.py

@@ -30,7 +30,7 @@ def as_list(item, type=None, length=None):
 
 def as_tuple(item, type=None, length=None):
     """
-    Force item to a tuple.
+    Force item to a tuple. Passes tuple subclasses through also.
 
     Partly extracted from: https://github.com/OP2/PyOP2/.
     """
@@ -39,13 +39,17 @@ def as_tuple(item, type=None, length=None):
         t = ()
     elif isinstance(item, (str, sympy.Function)):
         t = (item,)
+    elif isinstance(item, tuple):
+        # this makes tuple subclasses pass through
+        t = item
     else:
         # Convert iterable to list...
         try:
             t = tuple(item)
         # ... or create a list of a single item
         except (TypeError, NotImplementedError):
             t = (item,) * (length or 1)
+
     if length and not len(t) == length:
         raise ValueError("Tuple needs to be of length %d" % length)
     if type and not all(isinstance(i, type) for i in t):