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SubjectRe: [RFC PATCH 3/4] x86/asm: Make alternative macro interfaces more clear and consistent

* Josh Poimboeuf <jpoimboe@redhat.com> wrote:

> On Thu, Aug 31, 2017 at 12:25:42PM -0500, Josh Poimboeuf wrote:
> > 2) Put "sp" in the clobbers list instead of as an i/o constraint. This
> > mostly works for GCC, and doesn't break clang. However, it causes
> > GCC to insert a "lea -0x10(%rbp),%rsp" in the epilogue of every
> > affected function.
>
> And maybe this extra instruction is negligible for performance and not a
> big deal? I might look at this one after the holiday too.

Please do statistics of how many functions are affected, on a defconfig-ish
kernel.

Thanks,

Ingo

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