[llvm] [X86] Remove X86RegisterInfo::getSEHRegNum. (PR #106866)

[Phoebe Wang via llvm-commits]

phoebewang wrote:

> > The ARM/AArch64 definition also look redundant.
> 
> ARM/AArch64 has callers and they don't populate the DenseMap in MCRegisterInfo like `X86_MC::initLLVMToSEHAndCVRegMapping` unless I missed it?

That's interesting. I saw MCStreamer::emitWinCFIPushReg will call `getSEHRegNum` and think it should work for ARM/AArch64 too.

https://github.com/llvm/llvm-project/pull/106866