https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77445
--- Comment #22 from Jeffrey A. Law <law at redhat dot com> --- In response to c#19. Yes, a thread path which is cold except for a hot block in the middle might be profitable to thread as it will sometimes expose path specific redundancies/simplifications in the hot block. Whether or not it does is mostly a function of the PHI nodes in the hot block. ISTM that these opportunities are most likely to arise if threading results in a degenerate PHI in the hot block. Which is something we ought to be able to test for. Not sure if that helps this testcase or not.
