[SLP] Factor out scalar type as a getter. NFC

[RKSimon]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

221

(style)

if (auto*SI = dyn_cast<StoreInst>(V))
  return SI->getValueOperand()->getType();
if (auto *CI = dyn_cast<CmpInst>(V))
  return CI->getOperand(0)->getType();
if (auto *IE = dyn_cast<InsertElementInst>(V))
  return IE->getOperand(1)->getType();
return V->getType();

[eopXD]

Update code

• Address comment

[RKSimon]

Is this really a NFC? Could some of the cases that just call getType() now call one of the dyn_cast variants?

Anyway, no objections from me - @ABataev any comments?

[eopXD]

Thank you @RKSimon for raising this question.

Regarding the code that calls ->getType() and don't have dynamic casts...

• Line 3494 can only be entered when instruction is a Instruction::Load.
• Use of line 3614 can only be used when TE.Scalars consist of Load instructions.
• Line 4909 is under case Instruction::Load
• Line 11147 is under the reduction part of SLP, by the cases in RecurKind I think load / store / cmp instructions are not involved here.

With all this said, I am not sure if any existing code will cause this "none functional change intended" patch to fail.

[ABataev]

llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

7195

What if we gather cmps here?

10070

What if we vectorize list of cmps here?