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

[Ingo Molnar]

* Josh Poimboeuf <jpoimboe@xxxxxxxxxx> 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