Add __rfloordiv__ to SIMD

The __rfloordiv__() is already supported by Int and Object. Furthermore,
the built-in SIMD has been extended to also support this method.

Signed-off-by: Peyman Barazandeh <peymanb@gmail.com>

stdlib/src/builtin/simd.mojo

@@ -653,6 +653,23 @@ struct SIMD[type: DType, size: Int = simdwidthof[type]()](
             var mask = ((rhs < 0) ^ (self < 0)) & (mod != 0)
             return div - mask.cast[type]()
 
+    @always_inline("nodebug")
+    fn __rfloordiv__(self, value: Self) -> Self:
+        """Returns the division of value and self rounded down to the nearest
+        integer.
+
+        # Constraints:
+            The element type of the SIMD vector must be numeric.
+
+        Args:
+            value: The value to divide on.
+
+        Returns:
+            `value // self`.
+        """
+        constrained[type.is_numeric(), "the type must be numeric"]()
+        return value // self
+
     @always_inline("nodebug")
     fn __mod__(self, rhs: Self) -> Self:
         """Returns the remainder of self divided by rhs.

stdlib/test/builtin/test_simd.mojo

@@ -102,6 +102,24 @@ def test_floordiv():
     assert_equal(Float32(2) // Float32(-2), -1)
     assert_equal(Float32(99) // Float32(-2), -50)
 
+    assert_equal(
+        SIMD[DType.int32, 4](2, 4, 1, 5) // Int32(2),
+        SIMD[DType.int32, 4](1, 2, 0, 2),
+    )
+    assert_equal(
+        SIMD[DType.float32, 4](3, -4, 1, 5) // Float32(3),
+        SIMD[DType.float32, 4](1, -2, 0, 1),
+    )
+
+    assert_equal(
+        Int32(2) // SIMD[DType.int32, 4](2, 4, -2, -4),
+        SIMD[DType.int32, 4](1, 0, -1, -1),
+    )
+    assert_equal(
+        Float32(3) // SIMD[DType.float32, 4](3, -4, 1, 5),
+        SIMD[DType.float32, 4](1, -1, 3, 0),
+    )
+
 
 def test_mod():
     assert_equal(Int32(99) % Int32(1), 0)