[PATCH] D20913: [asan] add primitives that allow coroutine implementations

[Dmitry Vyukov via llvm-commits]

dvyukov added a comment.

> I didn't think about that. I think you are right, it will cause the warning in __asan_handle_no_return and the false positives afterwards. However, I don't know how we could avoid that... The user doing the annotation could take care of that by deferring signals between the enter_fiber and the switch to the new stack. Do you have any other idea?


Requiring users to mess with it is unpleasant. And missing signal masks is not something you will instantly notice.

Also setting signal mask can slow down programs significantly. On my old program removal of signal mask change on context switches provided 7x end-to-end speedup. And I think swapcontext should do only one sigsetmask call, while disable/enable will be 2 syscalls.

If we express the annotations as start_switch/fnish_switch, then we have more flexibility to handle it. First, we can handle signal masks internally. Second, we can remember both old and new stacks for the duration of the switch, and then check both in __asan_handle_no_return. This will eliminate the need to mess with signal masks.


http://reviews.llvm.org/D20913