[PATCH] D95125: [WebAssembly] Enable loop unrolling

[Sam Parker via Phabricator via llvm-commits]

samparker added a comment.

> I'm inclined to merge this and leave it to users for whom the code size increase is unacceptable to use -Os/-Oz/-fno-unroll-loops to disable it.

The unrolling would be disabled at -Os and -Oz, see

  // Avoid unrolling when optimizing for size.
  UP.OptSizeThreshold = 0;
  UP.PartialOptSizeThreshold = 0;



> Is it possible to do this in -O3 but not -O2 or -O1?

AFAIK, loop unrolling is disabled at -O1 for all targets. I don't think there's currently a backend mechanism to make a decision on the opt level, but the loop unroller uses them to adjust thresholds to be more aggressive in some situations.


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  https://reviews.llvm.org/D95125/new/

https://reviews.llvm.org/D95125