[LLVMdev] Enabling MI Scheduler on x86 (was Experimental Evaluation of the Schedulers in LLVM 3.3)

Chandler Carruth chandlerc at google.com
Mon Sep 23 23:36:17 PDT 2013

On Tue, Sep 24, 2013 at 1:11 AM, Andrew Trick <atrick at apple.com> wrote:

> This week, I'll see if we can enable MI scheduling by default for x86. I'm
> not sure which flags you're using to test it now. But by making it default
> and enabling the corresponding coalescer changes, we can be confident that
> benchmarking efforts are improving on the same baseline.

While I'm generally really excited by this, I would ask for a bit more
staging of this change.

Specifically, I would really like for a single, clear switch to enable
exactly what you want benchmark data on *before* it becomes the default,
and to give various folks time to run benchmarks and report serious

I don't want our ability to ship LLVM from top-of-tree to be seriously
impaired by this, and enabling a feature that can have dramatic performance
impact without a giving folks a really simple way to try it out and a
period of time to run benchmarks and collect data seems to do that. =/

Once it is the default, it would be really good to leave in the single,
simple switch for a period of time for folks to disable it if need be.
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