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Builtins for WSE-3

This section documents CSL builtins that are only supported for WSE-3.

@set_control_task_table

Create a separate control task table.

Syntax

@set_control_task_table();
@set_control_task_table(config);

Where:

• config is a comptime-known (anonymous) struct with the following optional fields:

  • instructions

  • stride

Example

task foo() void {}
task bar() void {}

comptime {
  @bind_control_task(foo, @get_control_task_id(10));
  @bind_local_task(bar, @get_local_task_id(10));

  // Even though 'foo' and 'bar' have the same IDs they do not
  // clash because this call to @set_control_task_table will
  // decouple control tasks from data and local tasks. Control
  // tasks now have their own separate task table.
  @set_control_task_table(.{.instructions = 8, .stride = 4});
}

Semantics

The @set_control_task_table builtin will decouple control tasks from data and local tasks by creating a separate task table that is dedicated to control tasks.

The builtin can only be called at most once during the evaluation of a top-level comptime block.

It can have an optional argument that must be a comptime-known struct with two optional fields: instructions and stride.

If @set_control_task_table is called without an argument then the default values for instructions and stride will be used (see below).

The instructions field can be used to specify the number of instructions for each entry point in the new control task table. The number of instructions must be a comptime-known integer value within the valid set of options which are 2, 4 and 8. The default value is 4.

The stride field requires a comptime-known integer value that represents the stride - in number of entry points - per input queue’s local control table index (see @initialize_queue). Its value should be in the range [1, 7] and the default value is 1.

@get_ut_id

Create a value of type ut_id from the provided integer identifier.

Syntax

@get_ut_id(id);

Where:

• id is a comptime-known expression of any unsigned integer type, or a runtime expression of type u16.

Semantics

If id is comptime-known, the builtin will only accept integers in the target architecture’s valid range for microthread IDs.

If id is not comptime-known, its type must be u16. In this case no runtime checks are performed to ensure that id is within the range of valid microthread IDs.

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