[NFCI] Move cost estimation from TargetLowering to TargetTransformInfo.

[dfukalov]

Summary

TragetLowering had two last InstructionCost related getTypeLegalizationCost()
and getScalingFactorCost() members, but all other costs are processed in TTI.

E.g. it is not comfortable to use other TTI members in these two functions
overrided in a target.

Minor refactoring: getTypeLegalizationCost() now doesn't need DataLayout
parameter - it was always passed from TTI.

[dfukalov]

llvm/include/llvm/CodeGen/BasicTTIImpl.h

363

I'm not sure I should make it virtual (as it was in TLI) and mark it override in targets...

366–370

Perhaps TTI::getScalingFactorCost should be unified to TargetLoweringBase::AddrMode AM parameter.

[RKSimon]

Does anyone else have any comments?

llvm/include/llvm/CodeGen/BasicTTIImpl.h

363

The TTI classes use a CRTP layout - you shouldn't need virtual classes

366–370

Not sure about whether that's useful - LoopStrengthReduction seems to be the main user of this, and it has its own data structures. We're going to end up creating the AddrMode structure somewhere, it might as well be here.

[RKSimon]

@dfukalov reverse ping - what happened with this patch?

[dfukalov]

Rebased.
I thought we should wait for additional opinions on the patch...

[fhahn]

Consolidating all cost-query related functions in TTI makes sense to me.

llvm/include/llvm/CodeGen/BasicTTIImpl.h

366

this could be done independently?

[dfukalov]

llvm/include/llvm/CodeGen/BasicTTIImpl.h

366

Actually I added const since the removed TargetLoweringBase::getScalingFactorCost() was const.

[dfukalov]

Addressed comment.

[RKSimon]

llvm/include/llvm/CodeGen/TargetLowering.h

966

doxygen comment / description?

[dfukalov]

llvm/include/llvm/CodeGen/TargetLowering.h

966

I Just moved the declaration from private to public section to allow access it from BasicTTIImplBase<T>::getTypeLegalizationCost().
There was no description in previous place. The function returns pair of values, which are actually mainly used by getTypeAction() (uses first element of pair) and getTypeToTransformTo() (uses second element). These interfaces have descriptions (related to first and second element of pair respectively.
So, should I copy+combine these descriptions or move them? Or perhaps place references here or there (after move)?

[RKSimon]

llvm/include/llvm/CodeGen/TargetLowering.h

966

Yeah, a copy + combine + tweak should be OK - we just need a summary of what is expected. Cheers.

[dfukalov]

Added comment/description for getTypeConversion()

[RKSimon]

LGTM - cheers

[qianzhen]

llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.h

97

This function used to be a public member in TargetLowering (llvm/lib/Target/AMDGPU/SIISelLowering.h), is there a reason to declare it as a private member when it's moved in TTI? It makes this function inaccessible outside TTI.

[dfukalov]

llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.h

97

The only user of the function was TTI. Additionally this function was the last in TTL that used InstructionCost entity. So it was moved into TTI and became private. If one needs use the function outside of TTI it can be moved then to public section.

At the moment there are no other users of the function outside of TTI so I didn't see a reason to expose it.