[clang] [llvm] [OpenMP] Fix launch_bounds for OpenMP ompx_attribute (PR #195665)

[Kevin Sala Penades via llvm-commits]

kevinsala wrote:

@shiltian

The original `CreateLaunchBoundsAttr` function checks for the nvptx architecture when `MaxBlocks != nullptr` and nullifies it if the targeting architecture is older than sm_90. This is because `.maxclusterrank` attribute was added in sm_90. Additionally, `getOffloadArch` raises an assert if it's called for a non-nvptx architecture.

I don't think this architecture check should have been placed at this stage, but this PR is not intended to address that. A follow-up PR should be opened to fix that aspect if necessary.

https://github.com/llvm/llvm-project/pull/195665