[TTI] NFC: Change getVectorSplitCost to return InstructionCost

[dfukalov]

Summary

This patch migrates the TTI cost interfaces to return an InstructionCost.

See this patch for the introduction of the type: https://reviews.llvm.org/D91174
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2020-November/146408.html

[sdesmalen]

LGTM, thank you.

[dfukalov]

@sdesmalen I'm going next to change getTypeLegalizationCost() to return pair with InstructionCost.
Just want to know if you're working on it, to avoid work duplication, are you?

[sdesmalen]

In D100952#2705138, @dfukalov wrote:

@sdesmalen I'm going next to change getTypeLegalizationCost() to return pair with InstructionCost.
Just want to know if you're working on it, to avoid work duplication, are you?

No, I hadn't started with that one yet, thanks for the help!

When changing getTypeLegalizationCost to return a pair with InstructionCost, we can return Invalid for TypeScalarizeScalableVector, which has been left explicitly unimplemented because this is difficult to do, as it would require generating a loop during SelectionDAG.

llvm/include/llvm/CodeGen/BasicTTIImpl.h

if (IsMLA) {
       MulCost =
           thisT()->getArithmeticInstrCost(Instruction::Mul, ExtTy, CostKind);
       ExtCost *= 2;
     }
 
     return RedCost + MulCost + ExtCost;
   }
 
-  unsigned getVectorSplitCost() { return 1; }
+  InstructionCost getVectorSplitCost() { return 1; }
 
   /// @}
 };
 
 /// Concrete BasicTTIImpl that can be used if no further customization
 /// is needed.
 class BasicTTIImpl : public BasicTTIImplBase<BasicTTIImpl> {
   using BaseT = BasicTTIImplBase<BasicTTIImpl>;

llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.h

public:
   Optional<Instruction *> instCombineIntrinsic(InstCombiner &IC,
                                                IntrinsicInst &II) const;
   Optional<Value *> simplifyDemandedVectorEltsIntrinsic(
       InstCombiner &IC, IntrinsicInst &II, APInt DemandedElts, APInt &UndefElts,
       APInt &UndefElts2, APInt &UndefElts3,
       std::function<void(Instruction *, unsigned, APInt, APInt &)>
           SimplifyAndSetOp) const;
 
-  unsigned getVectorSplitCost() { return 0; }
+  InstructionCost getVectorSplitCost() { return 0; }
 
   InstructionCost getShuffleCost(TTI::ShuffleKind Kind, VectorType *Tp,
                                  ArrayRef<int> Mask, int Index,
                                  VectorType *SubTp);
 
   bool areInlineCompatible(const Function *Caller,
                            const Function *Callee) const;