compiler: Move opt_pows/fact next to unevaluation

Author: FabioLuporini

devito/core/cpu.py

@@ -177,7 +177,6 @@ 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

@@ -218,7 +218,6 @@ 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, 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)
 
+        # Turn pows into multiplications. This must happen as late as possible
+        # in the compilation process to maximize the optimization potential
+        clusters = optimize_pows(clusters)
+
         # Make sure no reconstructions can unpick any of the symbolic
         # optimizations performed so far
         clusters = unevaluate(clusters)

tests/test_dse.py

@@ -1745,7 +1745,7 @@ def g2_tilde(field, phi, theta):
         assert len([i for i in FindSymbols().visit(bns['x0_blk0']) if i.is_Array]) == 7
         assert len(FindNodes(VExpanded).visit(pbs['x0_blk0'])) == 3
 
-    @pytest.mark.parametrize('so_ops', [(4, 147), (8, 211)])
+    @pytest.mark.parametrize('so_ops', [(4, 146), (8, 210)])
     @switchconfig(profiling='advanced')
     def test_tti_J_akin_complete(self, so_ops):
         grid = Grid(shape=(16, 16, 16))
@@ -2725,9 +2725,9 @@ def test_fullopt(self):
         bns, _ = assert_blocking(op0, {})
         bns, _ = assert_blocking(op1, {'x0_blk0'})  # due to loop blocking
 
-        assert summary0[('section0', None)].ops == 50
+        assert summary0[('section0', None)].ops == 55
         assert summary0[('section1', None)].ops == 44
-        assert np.isclose(summary0[('section0', None)].oi, 2.851, atol=0.001)
+        assert np.isclose(summary0[('section0', None)].oi, 3.136, atol=0.001)
 
         assert summary1[('section0', None)].ops == 31
         assert summary1[('section1', None)].ops == 88
@@ -2779,7 +2779,7 @@ def tti_noopt(self):
         # Make sure no opts were applied
         op = wavesolver.op_fwd(False)
         assert len(op._func_table) == 0
-        assert summary[('section0', None)].ops == 743
+        assert summary[('section0', None)].ops == 753
 
         return v, rec
 
@@ -2865,7 +2865,7 @@ class TestTTIv2:
 
     @switchconfig(profiling='advanced')
     @pytest.mark.parametrize('space_order,expected', [
-        (4, 200), (12, 392)
+        (4, 190), (12, 382)
     ])
     def test_opcounts(self, space_order, expected):
         grid = Grid(shape=(3, 3, 3))

tests/test_unexpansion.py

@@ -260,7 +260,7 @@ def test_v4(self):
                                         'cire-mingain': 400}))
 
         # Check code generation
-        assert op._profiler._sections['section1'].sops == 1443
+        assert op._profiler._sections['section1'].sops == 1442
         assert_structure(op, ['x,y,z',
                               't,x0_blk0,y0_blk0,x,y,z',
                               't,x0_blk0,y0_blk0,x,y,z,i1',
@@ -431,7 +431,7 @@ def test_v1(self):
                                         'openmp': False}))
 
         # Check code generation
-        assert op._profiler._sections['section1'].sops == 191
+        assert op._profiler._sections['section1'].sops == 190
         assert_structure(op, ['x,y,z',
                               't,x0_blk0,y0_blk0,x,y,z',
                               't,x0_blk0,y0_blk0,x,y,z,i0',