[llvm] r324450 - [LoopPrediction] Introduce utility function getLatchPredicateForGuard. NFC.

[Philip Reames via llvm-commits]

"Striction"?


On 02/07/2018 08:45 PM, Serguei Katkov wrote:
> Hi Philip,
>
> how about the name " getFlippedStrictionPredicate" and move it to CmpInst class?
>
> Thank you,
> Serguei.
>
>> -----Original Message-----
>> From: Philip Reames [mailto:listmail at philipreames.com]
>> Sent: Thursday, February 8, 2018 4:28 AM
>> To: Serguei Katkov <serguei.katkov at azul.com>; llvm-commits at lists.llvm.org
>> Subject: Re: [llvm] r324450 - [LoopPrediction] Introduce utility function
>> getLatchPredicateForGuard. NFC.
>>
>> Serguei,
>>
>> "Latch predicate" doesn't mean much out of context here.  Can you either
>> find a more clear name or add a comment explaining the semantics of the
>> new function?
>>
>> Philip
>>
>>
>> On 02/06/2018 10:53 PM, Serguei Katkov via llvm-commits wrote:
>>> Author: skatkov
>>> Date: Tue Feb  6 22:53:37 2018
>>> New Revision: 324450
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=324450&view=rev
>>> Log:
>>> [LoopPrediction] Introduce utility function getLatchPredicateForGuard.
>> NFC.
>>> Factor out getting the predicate for latch condition in a guard to
>>> utility function getLatchPredicateForGuard.
>>>
>>> Modified:
>>>       llvm/trunk/lib/Transforms/Scalar/LoopPredication.cpp
>>>
>>> Modified: llvm/trunk/lib/Transforms/Scalar/LoopPredication.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/L
>>> oopPredication.cpp?rev=324450&r1=324449&r2=324450&view=diff
>>>
>> ==========================================================
>> ============
>>> ========
>>> --- llvm/trunk/lib/Transforms/Scalar/LoopPredication.cpp (original)
>>> +++ llvm/trunk/lib/Transforms/Scalar/LoopPredication.cpp Tue Feb  6
>>> +++ 22:53:37 2018
>>> @@ -266,6 +266,11 @@ class LoopPredication {
>>>      // Return the loopLatchCheck corresponding to the RangeCheckType if
>> safe to do
>>>      // so.
>>>      Optional<LoopICmp> generateLoopLatchCheck(Type
>> *RangeCheckType);
>>> +
>>> +  // Returns the latch predicate for guard. SGT -> SGE, UGT -> UGE,
>>> + SGE -> SGT,  // UGE -> UGT, etc.
>>> +  ICmpInst::Predicate getLatchPredicateForGuard(ICmpInst::Predicate
>>> + Pred);
>>> +
>>>    public:
>>>      LoopPredication(ScalarEvolution *SE) : SE(SE){};
>>>      bool runOnLoop(Loop *L);
>>> @@ -391,6 +396,30 @@ bool LoopPredication::CanExpand(const SC
>>>      return SE->isLoopInvariant(S, L) && isSafeToExpand(S, *SE);
>>>    }
>>>
>>> +ICmpInst::Predicate
>>> +LoopPredication::getLatchPredicateForGuard(ICmpInst::Predicate Pred)
>>> +{
>>> +  switch (LatchCheck.Pred) {
>>> +  case ICmpInst::ICMP_ULT:
>>> +    return ICmpInst::ICMP_ULE;
>>> +  case ICmpInst::ICMP_ULE:
>>> +    return ICmpInst::ICMP_ULT;
>>> +  case ICmpInst::ICMP_SLT:
>>> +    return ICmpInst::ICMP_SLE;
>>> +  case ICmpInst::ICMP_SLE:
>>> +    return ICmpInst::ICMP_SLT;
>>> +  case ICmpInst::ICMP_UGT:
>>> +    return ICmpInst::ICMP_UGE;
>>> +  case ICmpInst::ICMP_UGE:
>>> +    return ICmpInst::ICMP_UGT;
>>> +  case ICmpInst::ICMP_SGT:
>>> +    return ICmpInst::ICMP_SGE;
>>> +  case ICmpInst::ICMP_SGE:
>>> +    return ICmpInst::ICMP_SGT;
>>> +  default:
>>> +    llvm_unreachable("Unsupported loop latch!");
>>> +  }
>>> +}
>>> +
>>>    Optional<Value *>
>> LoopPredication::widenICmpRangeCheckIncrementingLoop(
>>>        LoopPredication::LoopICmp LatchCheck, LoopPredication::LoopICmp
>> RangeCheck,
>>>        SCEVExpander &Expander, IRBuilder<> &Builder) { @@ -415,23
>>> +444,7 @@ Optional<Value *> LoopPredication::widen
>>>        DEBUG(dbgs() << "Can't expand limit check!\n");
>>>        return None;
>>>      }
>>> -  ICmpInst::Predicate LimitCheckPred;
>>> -  switch (LatchCheck.Pred) {
>>> -  case ICmpInst::ICMP_ULT:
>>> -    LimitCheckPred = ICmpInst::ICMP_ULE;
>>> -    break;
>>> -  case ICmpInst::ICMP_ULE:
>>> -    LimitCheckPred = ICmpInst::ICMP_ULT;
>>> -    break;
>>> -  case ICmpInst::ICMP_SLT:
>>> -    LimitCheckPred = ICmpInst::ICMP_SLE;
>>> -    break;
>>> -  case ICmpInst::ICMP_SLE:
>>> -    LimitCheckPred = ICmpInst::ICMP_SLT;
>>> -    break;
>>> -  default:
>>> -    llvm_unreachable("Unsupported loop latch!");
>>> -  }
>>> +  auto LimitCheckPred = getLatchPredicateForGuard(LatchCheck.Pred);
>>>
>>>      DEBUG(dbgs() << "LHS: " << *LatchLimit << "\n");
>>>      DEBUG(dbgs() << "RHS: " << *RHS << "\n");
>>>
>>>
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