gpu slice support null output

mindspore/ccsrc/kernel/gpu/arrays/slice_gpu_kernel.h

@@ -27,7 +27,8 @@ namespace kernel {
 template <typename T>
 class SliceGpuFwdKernel : public GpuKernel {
  public:
-  SliceGpuFwdKernel() : is_strided_slice_(false), input_size_(0), output_size_(0), workspace_size_(0) {}
+  SliceGpuFwdKernel()
+      : is_strided_slice_(false), is_null_input_(false), input_size_(0), output_size_(0), workspace_size_(0) {}
   ~SliceGpuFwdKernel() override = default;
   const std::vector<size_t> &GetInputSizeList() const override { return input_size_list_; }
   const std::vector<size_t> &GetOutputSizeList() const override { return output_size_list_; }
@@ -35,6 +36,9 @@ class SliceGpuFwdKernel : public GpuKernel {
 
   bool Launch(const std::vector<AddressPtr> &inputs, const std::vector<AddressPtr> &,
               const std::vector<AddressPtr> &outputs, void *stream_ptr) override {
+    if (is_null_input_) {
+      return true;
+    }
     T *input = GetDeviceAddress<T>(inputs, 0);
     T *output = GetDeviceAddress<T>(outputs, 0);
     if (is_strided_slice_) {
@@ -79,7 +83,11 @@ class SliceGpuFwdKernel : public GpuKernel {
       if (size_[i] < 0) {
         size_[i] = (size_[i] + input_shape_[i]) > 0 ? (size_[i] + input_shape_[i]) : 0;
       }
-      if (size_[i] == 0) {
+      if (begin_[i] == size_[i] && is_strided_slice_) {
+        MS_LOG(WARNING) << "Output is null.";
+        is_null_input_ = true;
+      }
+      if (size_[i] == 0 && strides_[i] > 0) {
         size_[i] = begin_[i] + 1;
       }
     }
@@ -143,6 +151,7 @@ class SliceGpuFwdKernel : public GpuKernel {
   std::vector<size_t> workspace_size_list_;
 
   bool is_strided_slice_;
+  bool is_null_input_;
   size_t input_size_;
   size_t output_size_;
   size_t workspace_size_;