Re: [Qemu-devel] [PATCH 4/5] tcg/i386: use movbe instruction in qemu_ldst routines

[Richard Henderson]

On 12/21/2013 08:43 AM, Aurelien Jarno wrote:
> +/* If bit_MOVBE is defined in cpuid.h (added in GCC version 4.6), we are
> +   going to attempt to determine at runtime whether movbe is available.  */
> +#if defined(CONFIG_CPUID_H) && defined(bit_MOVBE)
> +static bool have_movbe;
> +#else
> +# define have_movbe 0
> +#endif
> +

Good point about checking bit_MOVBE, I missed that in my version.

I do slightly prefer hoisting the mov opcode, as I do in my version.
I think that tidies the 32 and 64-bit paths a bit.  Nothing can really help
adding extra conditionals to the 16-bit load paths though.


r~