[IR] IRBuilderBase::CreateBinaryIntrinsic - attempt constant folding

[RKSimon]

c411965 has to handle constant folding of many common intrinsics because IRBuilderBase doesn't currently handle it:

Intrinsic::smax
Intrinsic::smin
Intrinsic::umax
Intrinsic::umin
Intrinsic::maxnum
Intrinsic::minnum

Can we add a suitable IRBuilderFolder::FoldBinaryIntrinsics function?

[llvmbot]

Hi!

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If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

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

Author: Simon Pilgrim (RKSimon)

c411965 has to handle constant folding of many common intrinsics because `IRBuilderBase` doesn't currently handle it:

Intrinsic::smax
Intrinsic::smin
Intrinsic::umax
Intrinsic::umin
Intrinsic::maxnum
Intrinsic::minnum

Can we add a suitable IRBuilderFolder::FoldBinaryIntrinsics function?

[fhahn]

Sounds like a great idea!

[agentcooper]

@RKSimon @fhahn I'm attempting to do this in #80743 and need some guidance. Could you please take a look and say if the general direction is right? I've left a few TODOs in the PR as well.