[llvm] [NewPM][CodeGen] Add `MachineFunctionAnalysis` (PR #88610)

[Akshat Oke via llvm-commits]

optimisan wrote:

Having the `InvalidateAnalysisPass<MachineFunctionAnalysis>()` is causing a problem with `ModuleToCGSCCPassAdaptor` (MtoCGPA) by deleting machine functions for other functions and ending up with empty compiled functions.

This is because `ModuleToCGSCCPAdaptor` propagates `PassPA` (received from the `CGSCCToFunctionPassAdaptor` that runs the actual codegen pipeline on MFs) to the next SCC. That causes `MFA` invalidation on functions in the next SCC. 

For us, `PassPA` happens to be returned from `invalidate<machine-function-analysis>` which `abandons` the `MachineFunctionAnalysis`. So while the first function runs through the pipeline normally, `invalidate` also deletes the functions in the next SCC before its pipeline is run. (this seems to be the intended mechanism of the `CG adaptor` to allow cross-SCC invalidations.

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The most obvious solution is to stop using the invalidation framework to free machine functions. This would mean we have to store MFs out of the FAM.

I'm still not a 100% sure of how the ModuleToCGSCCPassAdaptor invalidation mechanism is handling this, so there could be a better way to deal with this, what do you think?

@aeubanks @paperchalice 

https://github.com/llvm/llvm-project/pull/88610