Make clear if using manufactured coordinates coefficient

So that caller can replace if necessary

Author: ReubenHill

tsfc/driver.py

@@ -332,15 +332,16 @@ def compile_expression_dual_evaluation(expression, to_element, *,
         domain = expression.ufl_domain()
     assert domain is not None
 
-    # Create a fake coordinate coefficient for a domain.
-    coords_coefficient = ufl.Coefficient(ufl.FunctionSpace(domain, domain.ufl_coordinate_element()))
-    builder.domain_coordinate[domain] = coords_coefficient
-    builder.set_cell_sizes(domain)
-
     # Collect required coefficients
+    first_coefficient_fake_coords = False
     coefficients = extract_coefficients(expression)
     if has_type(expression, GeometricQuantity) or any(fem.needs_coordinate_mapping(c.ufl_element()) for c in coefficients):
+        # Create a fake coordinate coefficient for a domain.
+        coords_coefficient = ufl.Coefficient(ufl.FunctionSpace(domain, domain.ufl_coordinate_element()))
+        builder.domain_coordinate[domain] = coords_coefficient
+        builder.set_cell_sizes(domain)
         coefficients = [coords_coefficient] + coefficients
+        first_coefficient_fake_coords = True
     builder.set_coefficients(coefficients)
 
     # Split mixed coefficients
@@ -433,7 +434,7 @@ def compile_expression_dual_evaluation(expression, to_element, *,
     # Handle kernel interface requirements
     builder.register_requirements([ir])
     # Build kernel tuple
-    return builder.construct_kernel(return_arg, impero_c, index_names)
+    return builder.construct_kernel(return_arg, impero_c, index_names, first_coefficient_fake_coords)
 
 
 def lower_integral_type(fiat_cell, integral_type):

tsfc/kernel_interface/firedrake_loopy.py

@@ -17,7 +17,7 @@
 
 
 # Expression kernel description type
-ExpressionKernel = namedtuple('ExpressionKernel', ['ast', 'oriented', 'needs_cell_sizes', 'coefficients', 'tabulations'])
+ExpressionKernel = namedtuple('ExpressionKernel', ['ast', 'oriented', 'needs_cell_sizes', 'coefficients', 'first_coefficient_fake_coords', 'tabulations'])
 
 
 def make_builder(*args, **kwargs):
@@ -153,12 +153,14 @@ def register_requirements(self, ir):
         provided by the kernel interface."""
         self.oriented, self.cell_sizes, self.tabulations = check_requirements(ir)
 
-    def construct_kernel(self, return_arg, impero_c, index_names):
+    def construct_kernel(self, return_arg, impero_c, index_names, first_coefficient_fake_coords):
         """Constructs an :class:`ExpressionKernel`.
 
         :arg return_arg: loopy.GlobalArg for the return value
         :arg impero_c: gem.ImperoC object that represents the kernel
         :arg index_names: pre-assigned index names
+        :arg first_coefficient_fake_coords: If true, the kernel's first
+            coefficient is a constructed UFL coordinate field
         :returns: :class:`ExpressionKernel` object
         """
         args = [return_arg]
@@ -173,7 +175,8 @@ def construct_kernel(self, return_arg, impero_c, index_names):
         loopy_kernel = generate_loopy(impero_c, args, self.scalar_type,
                                       "expression_kernel", index_names)
         return ExpressionKernel(loopy_kernel, self.oriented, self.cell_sizes,
-                                self.coefficients, self.tabulations)
+                                self.coefficients, first_coefficient_fake_coords,
+                                self.tabulations)
 
 
 class KernelBuilder(KernelBuilderBase):