[PATCH] D58391: [TailCallElim] Add tailcall elimination pass to LTO Pipelines

[Robert Lougher via Phabricator via llvm-commits]

rob.lougher added a comment.

In D58391#1408322 <https://reviews.llvm.org/D58391#1408322>, @tejohnson wrote:

>




> Regarding this patch, the change seems reasonable but I suppose any new addition to the regular LTO pipeline needs to consider the compile time vs performance tradeoff. If this patch is not too expensive then IMO it is fine to add.

Sorry for the delay, it has taken some time to get compile times. I have built two very large internal codebases 10 times each with and without the pass in the LTO pipeline. The mean compile time difference (with - without as percentage of without) was:

Codebase1: -0.03%
Codebase2: -0.56%

The results are negative, because the compile time was very slightly faster with the pass. However, the values are too small to be significant. The standard deviation of the compile times was (given as a percentage of the mean):

Codebase1:  without: 0.40% with: 0.41%
Codebase2: without: 0.33% with: 0.49%

As the results were not what I was expecting, I checked everything and repeated the builds. This confirmed the first results (mean compile time very slightly faster with the pass).


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D58391/new/

https://reviews.llvm.org/D58391