[PATCH] D53824: [HotColdSplitting] Allow outlining single-block cold regions

[Vedant Kumar via Phabricator via llvm-commits]

vsk created this revision.
vsk added reviewers: sebpop, hiraditya, tejohnson.

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.


https://reviews.llvm.org/D53824

Files:
  llvm/lib/Transforms/IPO/HotColdSplitting.cpp
  llvm/test/Transforms/HotColdSplit/do-not-split.ll
  llvm/test/Transforms/HotColdSplit/minsize.ll
  llvm/test/Transforms/HotColdSplit/split-out-dbg-val-of-arg.ll

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