[llvm-commits] [PATCH] Stack Coloring optimization

[Nadav Rotem]

Hi Sergei, 

Thanks for checking the patch and for the feedback. 

> I echo the concern expressed by Jakob, but after porting this patch to
> Hexagon and trying it out, in fairness, I see no performance impact (or real
> benefit) on our internal test suite,

This optimization reduces the used stack size. It is not supposed to change the execution time of your workloads.  

> which has the scenario you are trying
> to address here... (with the obvious caveat that it really operates as
> intended)...
> But if in the future, it will reduce in any way aliasing resolution during
> MI scheduling, this might become a serious issue for Hexagon.

This optimization pass comes to replace the inline-and-merge-hack which merges allocas in the IR.  

Performing slot-merging in the codegen will actually give you more control. If you find that slot-merging hurts MI scheduling then we can add code to allow you to control some of the thresholds.  

Thanks,
Nadav