compiler: fix division printing

Author: mloubout

devito/ir/cgen/printer.py

@@ -225,8 +225,20 @@ def _print_Mod(self, expr):
     def _print_Mul(self, expr):
         args = [a for a in expr.args if a != -1]
         neg = (len(expr.args) - len(args)) % 2
-
-        if len(args) > 1:
+        npow = [a for a in args if isinstance(a, sympy.Pow) and a.exp < 0]
+
+        if npow:
+            # Check if we have a fraction, i.e one of the arguments is a Pow(x, -1)
+            as_denom = lambda d: d.func(d.base, -d.exp) if d.exp != -1 else d.base
+            denom = expr.func(*[as_denom(d) for d in npow], evaluate=False)
+            # Numerator
+            numerator = expr.func(*[a for a in args if a not in npow], evaluate=False)
+            snumerator = self.parenthesize(numerator, precedence(expr))
+            # Denominator
+            sdenom = self.parenthesize(denom, precedence(expr))
+            # Plain division
+            term = f'{snumerator}/{sdenom}'
+        elif len(args) > 1:
             term = super()._print_Mul(expr.func(*args, evaluate=False))
         else:
             term = self.parenthesize(args[0], precedence(expr))

tests/test_symbolics.py

@@ -14,7 +14,7 @@
                               CallFromPointer, Cast, DefFunction, FieldFromPointer,
                               INT, FieldFromComposite, IntDiv, Namespace, Rvalue,
                               ReservedWord, ListInitializer, uxreplace, pow_to_mul,
-                              retrieve_derivatives, BaseCast)
+                              retrieve_derivatives, BaseCast, SizeOf)
 from devito.tools import as_tuple
 from devito.types import (Array, Bundle, FIndexed, LocalObject, Object,
                           ComponentAccess, StencilDimension, Symbol as dSymbol)
@@ -906,3 +906,10 @@ def define(self, dimensions):
 
     op = Operator(eq_u)
     assert '--' not in str(op.ccode)
+
+
+def test_print_div():
+    a = SizeOf(np.int32)
+    b = SizeOf(np.int64)
+    cstr = ccode(a / b)
+    assert cstr == 'sizeof(int)/sizeof(long)'