compiler: Move opt_pows/fact next to unevaluation

Author: FabioLuporini

devito/core/cpu.py

@@ -5,9 +5,9 @@
 from devito.operator.operator import rcompile
 from devito.passes import stream_dimensions
 from devito.passes.equations import collect_derivatives
-from devito.passes.clusters import (Lift, blocking, buffering, cire, cse,
-                                    factorize, fission, fuse, optimize_pows,
-                                    optimize_hyperplanes)
+from devito.passes.clusters import (
+    Lift, blocking, buffering, cire, cse, fission, fuse, optimize_hyperplanes
+)
 from devito.passes.iet import (CTarget, CXXTarget, COmpTarget, CXXOmpTarget,
                                avoid_denormals, linearize,
                                mpiize, hoist_prodders, relax_incr_dimensions,
@@ -176,8 +176,6 @@ def _specialize_clusters(cls, clusters, **kwargs):
 
         # Reduce flops
         clusters = cire(clusters, 'sops', sregistry, options, platform)
-        clusters = factorize(clusters, **kwargs)
-        clusters = optimize_pows(clusters)
 
         # The previous passes may have created fusion opportunities
         clusters = fuse(clusters)

devito/core/gpu.py

@@ -217,8 +217,6 @@ def _specialize_clusters(cls, clusters, **kwargs):
 
         # Reduce flops
         clusters = cire(clusters, 'sops', sregistry, options, platform)
-        clusters = factorize(clusters, **kwargs)
-        clusters = optimize_pows(clusters)
 
         # The previous passes may have created fusion opportunities
         clusters = fuse(clusters)

devito/operator/operator.py

@@ -29,7 +29,8 @@
 from devito.parameters import configuration
 from devito.passes import (
     Graph, lower_index_derivatives, generate_implicit, generate_macros,
-    minimize_symbols, unevaluate, error_mapper, is_on_device, lower_dtypes
+    minimize_symbols, factorize, optimize_pows, unevaluate, error_mapper,
+    is_on_device, lower_dtypes
 )
 from devito.symbolics import estimate_cost, subs_op_args
 from devito.tools import (DAG, OrderedSet, Signer, ReducerMap, as_mapper, as_tuple,
@@ -409,6 +410,10 @@ def _lower_clusters(cls, expressions, profiler=None, **kwargs):
         # Lower all remaining high order symbolic objects
         clusters = lower_index_derivatives(clusters, **kwargs)
 
+        # Reduce flops w/ structural changes
+        clusters = factorize(clusters, **kwargs)
+        clusters = optimize_pows(clusters)
+
         # Make sure no reconstructions can unpick any of the symbolic
         # optimizations performed so far
         clusters = unevaluate(clusters)