Changed layout for many summands

pystencils/backends/cbackend.py

@@ -609,6 +609,20 @@ class VectorizedCustomSympyPrinter(CustomSympyPrinter):
         return result
 
     def _print_Add(self, expr, order=None):
+        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['+']
+                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['+']
+                    return func.format(summands[0].term, visit(summands[elements:]))
+                else:
+                    func = self.instruction_set['+']
+                    return func.format(visit(summands[:elements]), visit(summands[elements:]))
+
         result = self._scalarFallback('_print_Add', expr)
         if result:
             return result
@@ -628,10 +642,13 @@ 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['-'] if summand.sign == -1 else self.instruction_set['+']
-            processed = func.format(processed, summand.term)
+        if len(summands) < 10:
+            processed = summands[0].term
+            for summand in summands[1:]:
+                func = self.instruction_set['-'] if summand.sign == -1 else self.instruction_set['+']
+                processed = func.format(processed, summand.term)
+        else:
+            processed = visit(summands)
         return processed
 
     def _print_Pow(self, expr):