Loop Directives
The following table summarizes the loop directives supported by OpenCL and their equivalents in SYCL*:
| OpenCL Syntax | SYCL Syntax | Description |
|---|---|---|
| #pragma disable_loop_pipelining | [[intel::disable_loop_pipelining]] | Disables pipelining of a loop. |
| #pragma ii <n> | [[intel::initiation_interval(n)]] | Attempts to set the II for the loop that follows the attribute declaration. |
Ignores memory dependencies carried by the loop that the attribute is applied to.
NOTE:
This attribute applies only to the loop it is applied to, and not to any of the future loops that might appear as a result of the [[intel::loop_coalesce(N)]] attribute.
CAUTION:
Applying the ivdep attribute incorrectly results in functionally incorrect hardware and potential functional differences between the hardware run and emulation. The ivdep attribute is ignored in emulation. |
||
| #pragma loop_coalesce <loop_nesting_level> | [[intel::loop_coalesce(N)]] | Coalesces nested loops into a single loop without affecting the loop functionality.
NOTE:
If you want to use the ivdep attribute to ignore loop-carried dependencies, apply it to the loop that causes dependencies and not to any of the future loops that might appear as a result of the [[intel::loop_coalesce(N)]] attribute. |
| #pragma max_concurrency(N) | [[intel::max_concurrency(n)]] | Limits the concurrency of a loop in your kernel. |
| #pragma max_interleaving N | [[intel::max_interleaving(n)]] | Maximizes the throughput and hardware resource occupancy of pipelined inner loops in a loop nest by issuing new inner loop iterations as frequently as possible (minimizing the loop initiation interval). |
| #pragma speculated_iterations k | [[intel::speculated_iterations(N)] | Specifies how many cycles the loop exit condition can take to compute. |
| #pragma unroll N | #pragma unroll N | Unrolls a loop. You can also use it to avoid unrolling a loop explicitly. |
| #pragma nofusion | [[intel::nofusion]] | Disables automatic loop fusion when compiling your design. |
| #pragma loop_fuse [depth(N)] [independent] | sycl::ext::intel::fpga_loop_fuse<v>(f) | Fuses loops within the function f and up to a depth of v >= 1. |
| sycl::ext::intel::fpga_loop_fuse_independent<v>(f) | Fuses loops within the function f up to a depth v >= 1 while overriding fusion-safety checks. |
Parent topic: Flags, Attributes, Directives, and Extensions