[ROCm] Fix non-stride-one backwards indexing performance (#2693)

cherry-pick of pytorch#164409

Author: doru1004

aten/src/ATen/native/cuda/Indexing.cu

@@ -55,9 +55,10 @@ constexpr uint64_t getDefaultMaxThreadsPerBlock() {
 #endif
 }
 
-#if 0
+#ifdef USE_ROCM
+#define SKIP_SORTED_INDICES 32
 template <typename scalar_t, int SZ>
-__global__ void indexing_backward_kernel(
+__global__ void indexing_backward_kernel_many_indices(
   const int64_t* sorted_indices, const int64_t* indices, const scalar_t* grad_output, scalar_t* grad_weight,
   int64_t numel, int64_t stride, int64_t stride_before, int64_t outer_dim, bool accumulate) {
   using opmath_t = at::opmath_type<scalar_t>;
@@ -140,10 +141,7 @@ __global__ void indexing_backward_kernel(
     }
   }
 }
-#endif
 
-#ifdef USE_ROCM
-#define SKIP_SORTED_INDICES 32
 template <typename scalar_t>
 __global__ void indexing_backward_kernel_stride_1(
   const int64_t* sorted_indices, const int64_t* indices, const scalar_t* grad_output, scalar_t* grad_weight,
@@ -790,6 +788,38 @@ void index_put_with_sort_kernel(Tensor & self, const c10::List<std::optional<Ten
             kBool,
             kBFloat16);
         } else {
+#ifdef USE_ROCM
+          if (num_indices >= 200000)
+            AT_DISPATCH_V2(
+              expandedValue.scalar_type(),
+              "indexing_backward_many_indices",
+              AT_WRAP([&] {
+                indexing_backward_kernel_many_indices<scalar_t, UNROLL><<<new_grid, block, smem_dups_size, stream>>>(
+                  sorted_indices.const_data_ptr<int64_t>(),
+                  orig_indices.const_data_ptr<int64_t>(),
+                  expandedValue.const_data_ptr<scalar_t>(),
+                  src_.mutable_data_ptr<scalar_t>(),
+                  num_indices,
+                  sliceSize,
+                  strideBefore,
+                  nElemBefore,
+                  accumulate);
+                C10_CUDA_KERNEL_LAUNCH_CHECK();
+              }),
+              AT_EXPAND(AT_ALL_TYPES_AND_COMPLEX),
+              // AT_EXPAND(AT_FLOAT8_TYPES),
+              // TODO(#113663): clean up accumulation behavior in float8 dtypes, accumulate=True
+              // should not be supported here, then reenable AT_FLOAT8_DTYPES
+              kFloat8_e4m3fn,
+              kFloat8_e5m2,
+              kFloat8_e4m3fnuz,
+              kFloat8_e5m2fnuz,
+              kComplexHalf,
+              kHalf,
+              kBool,
+              kBFloat16);
+          else
+#endif
           AT_DISPATCH_V2(
             expandedValue.scalar_type(),
             "indexing_backward",