[clang] [flang] [llvm] [flang] Add runtime trampoline pool for W^X compliance (PR #183108)

[Kiran Chandramohan via llvm-commits]

https://github.com/kiranchandramohan approved this pull request.

Looks great. Thanks for this work. What is the plan to enable by default?

Two Nit comments inline. 

LGTM.

https://github.com/llvm/llvm-project/pull/183108