[RESEND RFC PATCH v2 1/6] riscv/cmpxchg: Deduplicate cmpxchg() asm functions
Andrea Parri
parri.andrea at gmail.com
Tue Mar 21 17:45:14 PDT 2023
On Tue, Mar 21, 2023 at 04:42:44AM -0300, Leonardo Bras wrote:
> In this header every cmpxchg define (_relaxed, _acquire, _release,
> vanilla) contain it's own asm file, both for 4-byte variables an 8-byte
> variables, on a total of 8 versions of mostly the same asm.
>
> This is usually bad, as it means any change may be done in up to 8
> different places.
>
> Unify those versions by creating a new define with enough parameters to
> generate any version of the previous 8.
>
> (This did not cause any change in generated asm)
>
> Signed-off-by: Leonardo Bras <leobras at redhat.com>
> ---
> arch/riscv/include/asm/cmpxchg.h | 102 ++++++++-----------------------
> 1 file changed, 24 insertions(+), 78 deletions(-)
Diff looks nice,
> +#define ___cmpxchg(lr_sfx, sc_sfx, prepend, append) \
> +{ \
> + __asm__ __volatile__ ( \
> + prepend \
> + "0: lr" lr_sfx " %0, %2\n" \
> + " bne %0, %z3, 1f\n" \
> + " sc" sc_sfx " %1, %z4, %2\n" \
> + " bnez %1, 0b\n" \
> + append \
> + "1:\n" \
> + : "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \
> + : "rJ" ((long)__old), "rJ" (__new) \
> + : "memory"); \
> +}
Though I'm not really a fan of macros depending on local variables with
"magic" names, can this be avoided?
Thanks,
Andrea
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