[clang] [clang][CodeGen][SPIRV] Translate `amdgpu_flat_work_group_size` into `reqd_work_group_size`. (PR #116820)

[Yaxun Liu via cfe-commits]

yxsamliu wrote:

reqd_work_group_size is for OpenCL reqd_work_group_size attribute and it sets exact block size. amdgpu-flat-work-group-size sets a (min, max) range for block size. 

HIP launch bounds sets a block size range (1, bound). It cannot be represented by reqd_work_group_size.

https://github.com/llvm/llvm-project/pull/116820