[nfc][codegen] Move RegisterBank[Info].cpp under CodeGen

[mtrofin]

Summary

Layering-wise, it seems RegisterBank stuff fits under CodeGen, like
other target abstraction.
In particular, TargetSubtargetInfo has a getRegBankInfo member, but
using that object requires making sure GlobalISel is linked, which is
not always the case (e.g. llvm-jitlink doesn't).

[mtrofin]

If this change is actually OK/desirable, I can move the .h files over, too, and fix-up the includes. There are ~20 or so occurrences, so maybe I can do that in a subsequent patch (probably also see which are used, too)

[mtrofin]

gentle reminder - thanks!

[myhsu]

Just want to double check: You have a (possibly downstream) use case that wants to leverage RegisterBank without linking GlobalISel, is that correct?
My two-cent is that since none of the upstream code uses RegisterBank outside GlobalISel context, I don't see much justification on making this change. That said, if this situation changes in the upstream in the future (i.e. some other components also use RegisterBank) moving to CodeGen might be a way.

[mtrofin]

In D119053#3323575, @myhsu wrote:

Just want to double check: You have a (possibly downstream) use case that wants to leverage RegisterBank without linking GlobalISel, is that correct?

Yes, a subsequent change would do that: add bank-ness info as a feature to the ML eviction advisor.

My two-cent is that since none of the upstream code uses RegisterBank outside GlobalISel context, I don't see much justification on making this change. That said, if this situation changes in the upstream in the future (i.e. some other components also use RegisterBank) moving to CodeGen might be a way.

It could help others, too, hence wanted to introduce this "for its own merit" - i.e. the justification being cleanup (architectural, in this case).

llvm/lib/CodeGen/CMakeLists.txt

add_llvm_component_library(LLVMCodeGen
   MIRVRegNamerUtils.cpp
   MIRNamerPass.cpp
   MIRCanonicalizerPass.cpp
   RegisterUsageInfo.cpp
   RegUsageInfoCollector.cpp
   RegUsageInfoPropagate.cpp
   ReplaceWithVeclib.cpp
   ResetMachineFunctionPass.cpp
+  RegisterBank.cpp
+  RegisterBankInfo.cpp
   SafeStack.cpp
   SafeStackLayout.cpp
   ScheduleDAG.cpp
   ScheduleDAGInstrs.cpp
   ScheduleDAGPrinter.cpp
   ScoreboardHazardRecognizer.cpp
   ShadowStackGCLowering.cpp
   ShrinkWrap.cpp

llvm/lib/CodeGen/GlobalISel/CMakeLists.txt

add_llvm_component_library(LLVMGlobalISel
   LegalizerHelper.cpp
   LegalizerInfo.cpp
   LegacyLegalizerInfo.cpp
   LoadStoreOpt.cpp
   Localizer.cpp
   LostDebugLocObserver.cpp
   MachineIRBuilder.cpp
   RegBankSelect.cpp
-  RegisterBank.cpp
-  RegisterBankInfo.cpp
   Utils.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/CodeGen/GlobalISel
 
   DEPENDS
   intrinsics_gen