[mlir] AMDGPUToROCDL: lower `amdgpu.swizzle_bitmode` (#136223)

Repack `amdgpu.swizzle_bitmode` arguments and lower it to
`rocdl.ds_swizzle`.

Repacking logic is follows:
* `sizeof(arg) < sizeof(i32)`: bitcast to integer and zext to i32 and
then trunc and bitcast back.
* `sizeof(arg) == sizeof(i32)`: just bitcast to i32 and back if not i32
* `sizeof(arg) > sizeof(i32)`: bitcast to `vector<Nxi32>`, extract
individual elements and do a series of `rocdl.ds_swizzle` and then
compose vector and bitcast back.

Added repacking logic to LLVM utils so it can be used elsewhere. I'm
planning to use it for `gpu.shuffle` later.

0 files changed, 0 insertions, 0 deletions