fixed add printing

pystencils/backends/cbackend.py

@@ -631,15 +631,16 @@ class VectorizedCustomSympyPrinter(CustomSympyPrinter):
         def visit(summands):
             if len(summands) == 2:
                 sign = summands[0].sign * summands[1].sign
-                func = self.instruction_set['-'] if sign == -1 else self.instruction_set['+']
+                func = self.instruction_set['-' + suffix] if sign == -1 else self.instruction_set['+' + suffix]
                 return func.format(summands[0].term, summands[1].term)
             else:
                 elements = len(summands) // 2
                 if len(summands[:elements]) < 2:
-                    func = self.instruction_set['-'] if summands[0].sign == -1 else self.instruction_set['+']
+                    func = self.instruction_set['-' + suffix] \
+                        if summands[0].sign == -1 else self.instruction_set['+' + suffix]
                     return func.format(summands[0].term, visit(summands[elements:]))
                 else:
-                    func = self.instruction_set['+']
+                    func = self.instruction_set['+' + suffix]
                     return func.format(visit(summands[:elements]), visit(summands[elements:]))
         try:
             result = self._scalarFallback('_print_Add', expr)
@@ -675,10 +676,13 @@ class VectorizedCustomSympyPrinter(CustomSympyPrinter):
             summands.insert(0, self.SummandInfo(1, "0"))
 
         assert len(summands) >= 2
-        processed = summands[0].term
-        for summand in summands[1:]:
-            func = self.instruction_set['-' + suffix] if summand.sign == -1 else self.instruction_set['+' + suffix]
-            processed = func.format(processed, summand.term)
+        if len(summands) < 10:
+            processed = summands[0].term
+            for summand in summands[1:]:
+                func = self.instruction_set['-' + suffix] if summand.sign == -1 else self.instruction_set['+' + suffix]
+                processed = func.format(processed, summand.term)
+        else:
+            processed = visit(summands)
         return processed
 
     def _print_Pow(self, expr):