Enabled support for negative edge padding for XlaPad.

The underlying HLO pad already supports negative edge padding. We just removed
some checks preventing negative edge padding, and added a test.

PiperOrigin-RevId: 316672291
Change-Id: I38e55f86727d90f66aadb549a587b43df6588571

tensorflow/compiler/tests/xla_ops_test.py

@@ -211,6 +211,24 @@ class XlaOpsNumericalTest(xla_test.XLATestCase, parameterized.TestCase):
                [7, 7, 7, 7, 7], [7, 2, 3, 7, 7], [7, 7, 7, 7, 7]],
               dtype=dtype))
 
+  def testPadNegative(self):
+    for dtype in self.numeric_types:
+
+      def pad_fn(x):
+        return xla.pad(
+            x,
+            padding_value=7,
+            padding_low=[0, -1],
+            padding_high=[1, -2],
+            padding_interior=[1, 2])
+
+      self._assertOpOutputMatchesExpected(
+          pad_fn,
+          args=(np.arange(6, dtype=np.int32).astype(dtype).reshape([2, 3]),),
+          expected=np.array(
+              [[7, 7, 1, 7], [7, 7, 7, 7], [7, 7, 4, 7], [7, 7, 7, 7]],
+              dtype=dtype))
+
   @test_util.disable_mlir_bridge('Not supported yet')
   def testReduce(self):
     for dtype in set(self.numeric_types).intersection(

tensorflow/compiler/tf2xla/kernels/xla_pad_op.cc

@@ -64,14 +64,6 @@ class XlaPadOp : public XlaOpKernel {
                     padding_interior.size(), " vs. ", rank, ")"));
 
     auto non_negative = [](int64 x) { return x >= 0; };
-    OP_REQUIRES(
-        context, absl::c_all_of(padding_low, non_negative),
-        errors::InvalidArgument("padding_low must be non-negative, got [",
-                                absl::StrJoin(padding_low, ","), "]"));
-    OP_REQUIRES(
-        context, absl::c_all_of(padding_high, non_negative),
-        errors::InvalidArgument("padding_high must be non-negative, got [",
-                                absl::StrJoin(padding_high, ","), "]"));
     OP_REQUIRES(
         context, absl::c_all_of(padding_interior, non_negative),
         errors::InvalidArgument("padding_interior must be non-negative, got [",