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

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


================
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
----------------
asbirlea wrote:
> 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.
Oh, I wasn't aware that loop passes and loop nest passes can run in the same pass manager. That makes more sense indeed.


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

https://reviews.llvm.org/D109958