[PATCH] D93838: [SCCP] Add Function Specialization pass

[Sjoerd Meijer via Phabricator via llvm-commits]

SjoerdMeijer added a comment.

Thank you for further discussing this.

I have one more data point to add, related to compile-times which is probably the biggest concern for this work:

- Timed compilation of a non-LTO LLVM release build increases compile time with 0.6% and increases the binary with 0.003%. The code-size increase is not the point here. The point is that function specialisation triggers, with very modest compile-time increase.

Other compile-times discussed in this very lengthy thread show similar trends (for SPEC, MySQL).

Sorry for repeating myself, but I am looking for someone to bless this work, but let me say a few things on this:

- this will certainly need more tuning and experimentation,
- the goal is to get this on by default, like GCC, but depends on the previous point,
- getting this all right and enabled by default with the first commit is probably not achievable, hence why I am looking for a first commit.
- and given the interest in this work we can start sharing some of this when it is in tree.

@fhahn, as the kind of biggest supporter of "this must be on by default" early in the conversations, are you happy with this?


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