[PATCH] D93929: [NewPM][Hexagon] Fix HexagonVectorLoopCarriedReusePass position in pipeline

[Ankit via Phabricator via llvm-commits]

quic_aankit added a comment.

Aah Right. I remember now

In D93929#2485807 <https://reviews.llvm.org/D93929#2485807>, @aeubanks wrote:

> In D93929#2485715 <https://reviews.llvm.org/D93929#2485715>, @quic_aankit wrote:
>
>> @asbirlea I remember that HexagonVLCR pass has a dependency on LCSSA and LoopSimplifyPass. Is there any way we can run these passes too at LoopOptimizerEndEP? If not maybe use another EP for legacy PM? I'm not sure if the below code would run these passes in the correct order as well
>>
>>   PB.registerOptimizerLastEPCallback(
>>       [=](ModulePassManager &MPM, PassBuilder::OptimizationLevel Level) {
>>         LoopPassManager LPM(DebugPassManager);
>>         FunctionPassManager FPM(DebugPassManager);
>>         LPM.addPass(HexagonVectorLoopCarriedReusePass());
>>         FPM.addPass(LoopSimplifyPass());
>>         FPM.addPass(LCSSAPass());
>>         FPM.addPass(createFunctionToLoopPassAdaptor(std::move(LPM)));
>>         MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
>>       });
>>
>> @pranavb Can you comment more on this?
>
> LCSSA should be preserved by all loop passes under the new PM. LCSSA and LoopSimplify are run before any loop pass: https://github.com/llvm/llvm-project/blob/8dddcc762dd98d53b9406b36e92f62502834187c/llvm/include/llvm/Transforms/Scalar/LoopPassManager.h#L406. Although I don't think passes are required preserve loop simplify form.

Got it. In that case, the patch looks good to me.


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