revert swiglu dx zero set (#73680)

Author: phlrain

paddle/phi/kernels/swiglu_grad_kernel.h

@@ -45,14 +45,6 @@ void SwiGLUGradKernel(const Context &dev_ctx,
  }
  return;
  }
- if (dy && dy->numel() == 0) {
- dev_ctx.template Alloc<T>(dy);
- if (dx) {
- phi::Full<T, Context>(
- dev_ctx, phi::IntArray(common::vectorize(dx->dims())), 0, dx);
- }
- return;
- }
  const auto *x_ptr = x.data<T>();
  const auto *dz_ptr = dz.data<T>();
  auto *dx_ptr = dx ? dev_ctx.template Alloc<T>(dx) : nullptr;

test/legacy_test/test_swiglu.py

@@ -297,6 +297,7 @@ def test_swiglu(self):
  self.assertEqual(out[1].shape, y.shape)
 
 
+'''
 class TestSwigluOp_ZeroSize(OpTest):
  def config(self):
  self.x_shape = (0, 128)
@@ -338,6 +339,6 @@ def config(self):
  self.y_shape = (0, 128)
  self.out_shape = (0, 128)
 
-
+'''
 if __name__ == "__main__":
  unittest.main()