Given an atomic operation `w = max(w, x1, x2, ...)` rewrite it as `w =
max(w, max(x1, x2, ...))`. This will avoid unnecessary non-atomic
comparisons inside of the atomic operation (min/max are expanded
inline).
In particular, if some of the x_i's are optional dummy parameters in the
containing function, this will avoid any presence tests within the
atomic operation.
Fixes https://github.com/llvm/llvm-project/issues/144838
86077c41a7