`subgroup_broadcast` allow to broadcast the value from one lane to all
lanes in subgroup.
Supported modes:
* `first_active_lane` - broadcast value from the first active lane in
subgroup.
* `specific_lane` - broadcast value from the specified lane, lane index
must be within subgroup.
* `any_lane` - if `src` value is uniform across all the subgroup lanes
return it unchanged, otherwise result is poison. This variant
essentially an uniformity hint for the compiler, conveying that specific
value is uniform across all subgroup lanes. Dropping `any_lane`
broadcast should not change the code semantics.
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