[PATCH] D22639: Add flag to PassManagerBuilder to disable GVN Hoist Pass.

[Mehdi AMINI via llvm-commits]

mehdi_amini added a comment.

In https://reviews.llvm.org/D22639#491753, @bkramer wrote:

> The problem is not a Halide test but a scalability issue in MemorySSA that's making Halide unusable, consuming gigabytes of memory and taking forever. Personally, I don't think the GVNHoist pass is ready for prime time yet and needs more testing, like we did for other passes that were first rigorously tested under a flag before being enabled by default. Going directly from zero to default with a major new optimization infrastructure (MemSSA) is a recipe for disaster.


I agree with all of that and I missed the fact that it was not the regular plain old GVN that we were talking here but a new (and apparently still "experimental") pass.
With this in mind, a cl::opt flag seem appropriate and I waive my previous concern.
Thanks for the extra information!


https://reviews.llvm.org/D22639