compiler: Patch premature evaluation of saved TimeFunctions

Author: FabioLuporini

devito/types/dense.py

@@ -1593,15 +1593,6 @@ def _time_buffering(self):
     def _time_buffering_default(self):
         return self._time_buffering and not isinstance(self.save, Buffer)
 
-    def _evaluate(self, **kwargs):
-        retval = super()._evaluate(**kwargs)
-        if not self._time_buffering and not retval.is_Function:
-            # Saved TimeFunction might need streaming, expand interpolations
-            # for easier processing
-            return retval.evaluate
-        else:
-            return retval
-
     def _arg_check(self, args, intervals, **kwargs):
         super()._arg_check(args, intervals, **kwargs)
 

tests/test_derivatives.py

@@ -2,10 +2,11 @@
 import pytest
 from sympy import Float, Symbol, diff, simplify, sympify
 
+from conftest import assert_structure
 from devito import (
     NODE, ConditionalDimension, Eq, Function, Grid, Operator, TensorFunction,
-    TimeFunction, VectorFunction, centered, cos, curl, div, grad, laplace, left, right,
-    sin
+    TensorTimeFunction, TimeFunction, VectorFunction, centered, cos, curl, div,
+    grad, laplace, left, right, sin
 )
 from devito.finite_differences import Derivative, Differentiable, diffify
 from devito.finite_differences.differentiable import (
@@ -927,6 +928,17 @@ def test_param_stagg_add(self):
         # Addition should apply the same logic as above for each term
         assert simplify(eq2.evaluate.rhs - (expect1 + expect0)) == 0
 
+    def test_unexpand_space_interp_w_saved_timefunc(self):
+        grid = Grid(shape=(3, 3, 3))
+
+        tau = TensorTimeFunction(name="tau", grid=grid, save=10)
+
+        eq = Eq(tau[0,1], tau[2,2])
+
+        op = Operator(eq, opt=('advanced', {'expand': False}))
+
+        assert_structure(op, ['t,x,y,z', 't,x,y,z,i1', 't,x,y,z,i1,i0'])
+
 
 class TestTwoStageEvaluation: