Check if reduction symbol is (illegally) accessed before/after reduction assignment

src/pystencils/backend/kernelcreation/freeze.py

@@ -189,22 +189,12 @@ class FreezeExpressions:
     def map_ReductionAssignment(self, expr: ReductionAssignment):
         assert isinstance(expr.lhs, TypedSymbol)
 
-        # make sure that either:
-        # 1) lhs symbol never occurred
-        # 2) that it is at least known as lhs of an existing reduction operation
+        # make sure that lhs symbol never occurred before ReductionAssignment
         if self._ctx.find_symbol(expr.lhs.name):
-            # make sure that reduction operations are not mixed within a kernel
-            if info := self._ctx.find_reduction_info(expr.lhs.name):
-                if info.op is not expr.reduction_op:
-                    raise FreezeError(
-                        f"Different reduction operation {info.op} already exists "
-                        f"for {expr.lhs} with target reduction op {expr.reduction_op}."
-                    )
-            else:
-                raise FreezeError(
-                    f"Left-hand side {expr.lhs} of ReductionAssignment already exists in symbol table."
-                    f"Make sure that it is exclusively used within the kernel to conduct ReductionAssignment's."
-                )
+            raise FreezeError(
+                f"Left-hand side {expr.lhs} of ReductionAssignment already exists in symbol table. "
+                f"Make sure that it is only used once in a kernel's ReductionAssignment."
+            )
 
         lhs = self.visit(expr.lhs)
         rhs = self.visit(expr.rhs)
@@ -340,6 +330,16 @@ class FreezeExpressions:
 
     def map_TypedSymbol(self, expr: TypedSymbol):
         dtype = self._ctx.resolve_dynamic_type(expr.dtype)
+
+        # check if symbol is referenced after freezing a ReductionAssignment
+        if self._ctx.find_reduction_info(expr.name):
+            # check if types do not align since a ReductionAssignment modifies
+            # the symbol's type to PsPointerType in the context's symbol table
+            if (symbol := self._ctx.find_symbol(expr.name)) and symbol.dtype != dtype:
+                raise FreezeError(
+                    f"Illegal access to reduction symbol {symbol.name} after freezing a kernel's ReductionAssignment. "
+                )
+
         symb = self._ctx.get_symbol(expr.name, dtype)
         return PsSymbolExpr(symb)