[clang] [llvm] [X86] Support reserving EDI and ESI on x86-32 (PR #186123)

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zhouguangyuan0718 wrote:

> I think @efriedma-quic was opposited the 32-bit support. I'm inclined to not do it unless there's claer requirment.

Thanks, we are developing a [Go compiler based on LLVM](https://github.com/goplus/llgo),  for the closure context, we need a reserve register to pass it. And I hope it can be provided by llvm native.

https://github.com/llvm/llvm-project/pull/186123