Multi output primitives (#330)

* Multi-output primitives

---------

Co-authored-by: Angelos Katharopoulos <a_katharopoulos@apple.com>

tests/ops_tests.cpp

@@ -2397,3 +2397,58 @@ TEST_CASE("inner") {
   expected = array({7., 0., 0., 7.}, {2, 2});
   CHECK(array_equal(z, expected).item<bool>());
 }
+
+TEST_CASE("test divmod") {
+  auto x = array({1, 2, 3});
+  auto y = array({1, 1, 1});
+  auto out = divmod(x, y);
+  CHECK(array_equal(out[0], array({1, 2, 3})).item<bool>());
+  CHECK(array_equal(out[1], array({0, 0, 0})).item<bool>());
+
+  x = array({5, 6, 7});
+  y = array({2, 2, 2});
+  out = divmod(x, y);
+  CHECK(array_equal(out[0], array({2, 3, 3})).item<bool>());
+  CHECK(array_equal(out[1], array({1, 0, 1})).item<bool>());
+
+  // Siblings should be gone after evaling the graph
+  CHECK(out[0].siblings().empty());
+  CHECK(out[1].siblings().empty());
+
+  x = array({5.0, 6.0, 7.0});
+  y = array({2.0, 2.0, 2.0});
+  out = divmod(x, y);
+  CHECK(array_equal(out[0], array({2.0, 3.0, 3.0})).item<bool>());
+  CHECK(array_equal(out[1], array({1.0, 0.0, 1.0})).item<bool>());
+
+  x = array({1.0}, complex64);
+  y = array({2.0}, complex64);
+  CHECK_THROWS(divmod(x, y));
+
+  // Check that we can eval on both outputs
+  x = array({1.0});
+  y = array({2.0});
+  out = divmod(x, y);
+  eval(out);
+  CHECK_EQ(out[0].item<float>(), 0.0);
+  CHECK_EQ(out[1].item<float>(), 1.0);
+
+  // Check nested in the graph
+  x = array({1.0});
+  y = array({2.0});
+  out = divmod(x, y);
+  auto z = out[0] + out[1];
+  CHECK_EQ(z.item<float>(), 1.0);
+
+  // Check that we can still eval when one output goes out of scope
+  std::vector<array> out_holder;
+  { out_holder.push_back(divmod(x, y)[0]); }
+  eval(out_holder);
+  CHECK_EQ(out_holder[0].item<float>(), 0.0);
+
+  // Check that we can still eval when the other output goes out of scope
+  out_holder.clear();
+  { out_holder.push_back(divmod(x, y)[1]); }
+  eval(out_holder);
+  CHECK_EQ(out_holder[0].item<float>(), 1.0);
+}