[clang] [libclc] [llvm] [openmp] [Clang] `__attribute__((assume))` refactor (PR #84934)

[via llvm-commits]

Sirraide wrote:

Ok, I’ve removed the `omp_assume` spelling; `[[omp::assume]]` is now the only way to spell this attribute.

https://github.com/llvm/llvm-project/pull/84934