Draft: Fused-multiply-add vectorization

src/pystencils/backends/cbackend.py

@@ -571,6 +571,11 @@ class CustomSympyPrinter(CCodePrinter):
             return f"(({self._print(expr.args[0])}) / ({self._print(expr.args[1])}))"
         elif expr.func == DivFunc:
             return f'(({self._print(expr.divisor)}) / ({self._print(expr.dividend)}))'
+        elif isinstance(expr, Fma):
+            a = expr.args[0] * (-1 if expr.instruction[0] == '-' else 1)
+            b = expr.args[1]
+            c = expr.args[2] * (-1 if expr.instruction[-1] == '-' else 1)
+            return f"fma({self._print(a)}, {self._print(b)}, {self._print(c)})"
         else:
             name = expr.name if hasattr(expr, 'name') else expr.__class__.__name__
             arg_str = ', '.join(self._print(a) for a in expr.args)
@@ -729,6 +734,9 @@ class VectorizedCustomSympyPrinter(CustomSympyPrinter):
         elif isinstance(expr, fast_inv_sqrt):
             raise ValueError("fast_inv_sqrt is only supported for Taget.GPU")
         elif isinstance(expr, Fma):
+            result = self._scalarFallback('_print_Function', expr)
+            if result:
+                return result
             return self.instruction_set[expr.instruction].format(self._print(expr.args[0]), self._print(expr.args[1]),
                                                                  self._print(expr.args[2]), **self._kwargs)
         elif isinstance(expr, vec_any) or isinstance(expr, vec_all):