[Mlir-commits] [mlir] [mlir][gpu] Add `subgroup_broadcast` op (PR #152808)

[Ivan Butygin]

Hardcode84 wrote:

Yeah, the specified semantic of `any_lane` doesn't require any lowering if target cannot/don't want to.
The provided example
```
    $value = 1
    $result = 0
    if (lane_id & 0x1) 
       $result = subgroup.broadcast @any_lane $value
```
in reality looks like this when translated to SSA form
```
    $value = 1
    $result = 0
    $result1 = if (lane_id & 0x1) 
       yield subgroup.broadcast @any_lane $value
   else
      yield $result
```
And `subgroup.broadcast any_lane` can be dropped without changing the result

https://github.com/llvm/llvm-project/pull/152808