[HotColdSplitting] Allow outlining single-block cold regions
It can be profitable to outline single-block cold regions because they
may be large.
Allow outlining single-block regions if they have over some threshold of
non-debug, non-terminator instructions. I chose 3 as the threshold after
experimenting with several internal frameworks.
In practice, reducing the threshold further did not give much
improvement, whereas increasing it resulted in substantial regressions.
Differential Revision: https://reviews.llvm.org/D53824
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345524 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed