DPCT1085
Contents
DPCT1085#
Message#
The function <function name> requires sub-group size to be <size>, while other sub-group functions in the same SYCL kernel require a different sub-group size. You may need to adjust the code.
Detailed Help#
Each kernel can only be decorated with one sub-group size. This warning is emitted when a kernel requires different sub-group sizes. Check if the sub-group size can be unified into one value, and if it cannot be unified, redesign the code logic.
For example, this original CUDA* code:
1 _global_ void kernel() {
2 int Input, Output1, Output2, Lane;
3 ...
4
5 // original code logic
6 Output1 = __shfl(Input, Lane, 32);
7 Output2 = __shfl_xor(Input, Lane, 16);
8 }
results in the following migrated SYCL* code:
1 void kernel(int WarpSize, sycl::nd_item<3> item_ct1) {
2 int Input, Output1, Output2, Lane;
3 ...
4
5 // original code logic
6 Output1 = Item_ct1.get_sub_group().shuffle(Input, Lane, 32);
7 /* DPCT1085 */
8 Output2 = Item_ct1.get_sub_group().shuffle_xor(Input, Lane, 16);
9 }
which is manually adjusted to:
1 void kernel(int WarpSize, sycl::nd_item<3> item_ct1) {
2 int Input, Output, SrcLane;
3 ...
4
5 // redesigned code logic
6 Output1 = Item_ct1.get_sub_group().shuffle(Input, Lane, 32);
7 /* DPCT1085 */
8 // redesign the code logic to unify sub-group size in the same kernel
9 Output2 = Item_ct1.get_sub_group().shuffle_xor(Input, Lane, 32);
10 }
Suggestions to Fix#
Code requires manual fix. Rewrite the code manually.