[DAG] SelectionDAG::canCreateUndefOrPoison - add ISD::FABS handling + tests

[RKSimon]

Add ISD::FABS to SelectionDAG::canCreateUndefOrPoison along with suitable test coverage

[llvmbot]

Hi!

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[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Simon Pilgrim (RKSimon)

Add ISD::FABS to SelectionDAG::canCreateUndefOrPoison along with suitable test coverage

[ckoparkar]

I see ISD::FABS handled as following:

bool SelectionDAG::canCreateUndefOrPoison(...) {
...
  case ISD::BUILD_PAIR:
  case ISD::SPLAT_VECTOR:
  case ISD::FABS:
    return false;.
...

Does this need to change?

[RKSimon]

Oop - I missed that :)