[llvm] AMDGPU/GlobalISel: add RegBankLegalize rules for bitfield extract (PR #132381)

[Pierre van Houtryve via llvm-commits]

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@@ -225,6 +228,103 @@ void RegBankLegalizeHelper::lower(MachineInstr &MI,
     MI.eraseFromParent();
     break;
   }
+  case Div_BFE: {
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Pierre-vh wrote:

I feel like the contents of the `case` should be a helper, otherwise the switch becomes hard to read.
The code is also easier to follow with less indentation, and you can add a comment on the function to explain why/how it's lowered like this

https://github.com/llvm/llvm-project/pull/132381