Fix floor_div for multi-domain.

loopy/codegen/expression.py

@@ -310,9 +310,13 @@ class LoopyCCodeMapper(RecursiveMapper):
             raise RuntimeError("nothing known about variable '%s'" % expr.aggregate.name)
 
     def map_floor_div(self, expr, enclosing_prec, type_context):
+        from loopy.symbolic import get_dependencies
+        iname_deps = get_dependencies(expr) & self.kernel.all_inames()
+        domain = self.kernel.get_inames_domain(iname_deps)
+
         from loopy.isl_helpers import is_nonnegative
-        num_nonneg = is_nonnegative(expr.numerator, self.kernel.domain)
-        den_nonneg = is_nonnegative(expr.denominator, self.kernel.domain)
+        num_nonneg = is_nonnegative(expr.numerator, domain)
+        den_nonneg = is_nonnegative(expr.denominator, domain)
 
         if den_nonneg:
             if num_nonneg: