[PATCH] D87957: [LoopReroll][NewPM] Port -loop-reroll to NPM

[Arthur Eubanks via Phabricator via llvm-commits]

aeubanks added inline comments.


================
Comment at: llvm/lib/Transforms/Scalar/LoopRerollPass.cpp:1726
+  return LoopReroll(&AR.AA, &AR.LI, &AR.SE, &AR.TLI, &AR.DT, true).runOnLoop(&L)
+             ? PreservedAnalyses::none()
+             : PreservedAnalyses::all();
----------------
asbirlea wrote:
> Isn't anything preserved? LCSSA and AA perhaps?
> AFAICT, getLoopPassPreservedAnalyses() does not apply; DT, LI and ScEv are not preserved.
Sorry, I didn't notice that the legacy PM's `getLoopAnalysisUsage()` preserved some analyses.

I'm not super familiar with loop passes, but `getLoopPassPreservedAnalyses()` says 
```
/// Returns the minimum set of Analyses that all loop passes must preserve.
```
so why wouldn't that apply here?


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