Intel® DPC++ Compatibility Tool Developer Guide and Reference
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DPCT1089
Message
The value of the sub-group size attribute argument <argument name> cannot be evaluated. Replace dpct_placeholder with an integral constant expression.
Detailed Help
The argument to the attribute must be an integral constant expression. This warning is emitted when Intel® DPC++ Compatibility Tool cannot evaluate the value of the sub-group size argument as an integral constant expression. Check if the sub-group size attribute argument can be replaced by an integral constant expression, and if not, redesign the code logic.
For example, this original CUDA* code:
_global_ void kernel(int WarpSize) { int Input, Output, Lane; ... Output = __shfl(Input, Lane, WarpSize); }
...
if(condition)
{ kernel<<<GirdSize, BlockSize>>>(16); }
else
{ kernel<<<GirdSize, BlockSize>>>(32); }results in the following migrated SYCL* code:
void kernel(int WarpSize, sycl::nd_item<3> item_ct1) {
int Input, Output, Lane; ... Output = Item_ct1.get_sub_group().shuffle(Input, Lane);
}
...
if(condition) {
/* DPCT1089 */
q_ct1.parallel_for(
sycl::nd_range<3>(GridSize * BlockSize, BlockSize),
[=](sycl::nd_item<3> item_ct1) [[intel::reqd_sub_group_size(dpct_placeholder)]] { kernel(16, item_ct1); });
} else {
/* DPCT1089 */
q_ct1.parallel_for(
sycl::nd_range<3>(GridSize * BlockSize, BlockSize),
[=](sycl::nd_item<3> item_ct1) [[intel::reqd_sub_group_size(dpct_placeholder)]] { kernel(32, item_ct1); }
}which is manually adjusted to:
void kernel(int WarpSize, sycl::nd_item<3> item_ct1) { int Input, Output, Lane; ... Output = Item_ct1.get_sub_group().shuffle(Input, Lane); }
...
if(condition) {
/* DPCT1089 */
q_ct1.parallel_for(
sycl::nd_range<3>(GridSize * BlockSize, BlockSize),
[=](sycl::nd_item<3> item_ct1) [[intel::reqd_sub_group_size(16)]]
{ kernel(16, item_ct1); }
);
} else {
/* DPCT1089 */
q_ct1.parallel_for(
sycl::nd_range<3>(GridSize * BlockSize, BlockSize),
[=](sycl::nd_item<3> item_ct1) [[intel::reqd_sub_group_size(32)]]
{ kernel(32, item_ct1); }
}Suggestions to Fix
Code requires manual fix. Replace “dpct_placeholder” with an integral constant expression.