RE: [PATCH v3 3/6] x86/gsseg: make asm_load_gs_index() take an u16

David Laight
2022-10-14T12:28:43Z

From: Xin Li
> Sent: 13 October 2022 21:02
>
> From: "H. Peter Anvin (Intel)" <hpa@zytor.com>
>
> Let gcc know that only the low 16 bits of load_gs_index() argument
> actually matter. It might allow it to create slightly better
> code. However, do not propagate this into the prototypes of functions
> that end up being paravirtualized, to avoid unnecessary changes.

Using u16 will almost always make the code worse.
At some point the value has to be masked and/or extended
to ensure an out of range value doesn't appear in
a register.

David

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