[PATCH] D105131: Change the phase ordering of SROA in the LTO to enable more cse opportunities

Tue Jun 29 11:08:01 PDT 2021

fhahn added a comment.

In D105131#2847878 <https://reviews.llvm.org/D105131#2847878>, @jinlin wrote:

> Got you. The new pass manager is enabled by default starting from LLVM 12. I am using xcode 12.4 which uses prior version of llvm.

The default of a specific Xcode version is not really relevant to upstream LLVM.  If you build & use your own version of `libLTO`  with Xcode's` `ld`, it would use the default of the upstream project anyways, right?

If this change has clear benefits, it should be used by both the new pass manager and the legacy one.  Otherwise there may be additional regressions when the new pass manager is used.

To move forward with the patch, it would be good to include a phase-ordering test that shows the improvement of the new order.  It would also be helpful if you could provide data on the impact in term of code-size and runtime performance on a larger set of programs/benchmarks to motivate the change.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D105131/new/

https://reviews.llvm.org/D105131