[PATCH] D109958: [LoopFlatten] Enable it by default

[Alina Sbirlea via Phabricator via llvm-commits]

asbirlea added a comment.

It would be good to have some performance testing for this too.



================
Comment at: llvm/test/Other/new-pm-defaults.ll:168
+; CHECK-O-NEXT: Running pass: LoopSimplifyPass
+; CHECK-O-NEXT: Running pass: LCSSAPass
 ; CHECK-O-NEXT: Running pass: LoopIdiomRecognizePass
----------------
aeubanks wrote:
> nikic wrote:
> > As a drive-by comment for @asbirlea and @aeubanks, it looks like there's an opportunity here to not rerun LoopSimplify/LCSSA if we run multiple Loop/LoopNest pass managers back to back?
> we need to fix where we add `LoopFlattenPass` in PassBuilderPipelines.cpp
> 
> instead of
> 
> ```
>   if (EnableLoopFlatten)
>     FPM.addPass(createFunctionToLoopPassAdaptor(LoopFlattenPass()));
> ```
> we should move it earlier to
> ```
>   if (EnableLoopFlatten)
>     LPM2.addPass(LoopFlattenPass());
> ```
+1 it should be added to a LPM.


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  https://reviews.llvm.org/D109958/new/

https://reviews.llvm.org/D109958