Re: [Qemu-ppc] [Qemu-devel] [PATCH 28/32] ppc: Avoid double translation for lvx/lvxl/stvx/stvxl

[Richard Henderson]

On 07/29/2016 02:30 PM, Benjamin Herrenschmidt wrote:
>  DEF_HELPER_3(lmw, void, env, tl, i32)
> -DEF_HELPER_3(stmw, void, env, tl, i32)
> +DEF_HELPER_FLAGS_3(stmw, TCG_CALL_NO_WG, void, env, tl, i32)
>  DEF_HELPER_4(lsw, void, env, tl, i32, i32)
>  DEF_HELPER_5(lswx, void, env, tl, i32, i32, i32)
> -DEF_HELPER_4(stsw, void, env, tl, i32, i32)
> -DEF_HELPER_3(dcbz, void, env, tl, i32)
> -DEF_HELPER_2(icbi, void, env, tl)
> +DEF_HELPER_FLAGS_4(stsw, TCG_CALL_NO_WG, void, env, tl, i32, i32)
> +DEF_HELPER_FLAGS_3(dcbz, TCG_CALL_NO_WG, void, env, tl, i32)
> +DEF_HELPER_FLAGS_2(icbi, TCG_CALL_NO_WG, void, env, tl)
>  DEF_HELPER_5(lscbx, tl, env, tl, i32, i32, i32)
>
>  #if defined(TARGET_PPC64)
>
> If my understanding is right, the above is correct, as none of these
> instructions will write to the env, though they can read from it and/
> or generate faults.
>
> Sadly I haven't observed any performance improvement as a result in
> a few micro-benchmarks I cooked up.

Too bad.

But the changes look correct, so you might as well queue them.  ;-)


r~