api: Start enabling specialization at operator apply

Author: EdCaunt

devito/ir/iet/visitors.py

@@ -45,6 +45,7 @@
     'MapExprStmts',
     'MapHaloSpots',
     'MapNodes',
+    'Specializer',
     'Transformer',
     'Uxreplace',
     'printAST',

devito/operator/operator.py

@@ -22,7 +22,7 @@
 from devito.ir.equations import LoweredEq, concretize_subdims, lower_exprs
 from devito.ir.iet import (
     Callable, CInterface, DeviceFunction, EntryFunction, FindSymbols, MetaCall,
-    derive_parameters, iet_build
+    Specializer, derive_parameters, iet_build
 )
 from devito.ir.stree import stree_build
 from devito.ir.support import AccessMode, SymbolRegistry
@@ -986,16 +986,34 @@ def apply(self, **kwargs):
         >>> op = Operator(Eq(u3.forward, u3 + 1))
         >>> summary = op.apply(time_M=10)
         """
-        # Compile the operator before building the arguments list
-        # to avoid out of memory with greedy compilers
-        cfunction = self.cfunction
+        # Get items expected to be specialized
+        specialize = as_tuple(kwargs.pop('specialize', []))
+
+        if not specialize:
+            # Compile the operator before building the arguments list
+            # to avoid out of memory with greedy compilers
+            cfunction = self.cfunction
 
         # Build the arguments list to invoke the kernel function
         with self._profiler.timer_on('arguments-preprocess'):
             args = self.arguments(**kwargs)
         with switch_log_level(comm=args.comm):
             self._emit_args_profiling('arguments-preprocess')
 
+        # In the case of specialization, arguments must be processed before
+        # the operator can be compiled
+        if specialize:
+            specialized_args = {p: sympify(args.pop(p.name))
+                                for p in self.parameters if p.name in specialize}
+
+            op = Specializer(specialized_args).visit(self)
+        else:
+            op = self
+
+        from IPython import embed; embed()
+
+        # TODO: Whose profiler should get used here?
+
         # Invoke kernel function with args
         arg_values = [args[p.name] for p in self.parameters]
         try: