Re: [PATCH 00/13] [RFC] Rust support

[Peter Zijlstra]

On Sat, Apr 17, 2021 at 01:46:23PM +0200, Willy Tarreau wrote:
> For me the old trick of casting one side as long long still works:
> 
>   unsigned long long mul3264(unsigned int a, unsigned int b)
>   {
>         return (unsigned long long)a * b;
>   }
> 
> i386:
>   00000000 <mul3264>:
>      0: 8b 44 24 08           mov    0x8(%esp),%eax
>      4: f7 64 24 04           mull   0x4(%esp)
>      8: c3                    ret    
> 
> x86_64:
>   0000000000000000 <mul3264>:
>      0: 89 f8                 mov    %edi,%eax
>      2: 89 f7                 mov    %esi,%edi
>      4: 48 0f af c7           imul   %rdi,%rax
>      8: c3                    retq   
> 
> Or maybe you had something else in mind ?

Last time I tried it, the thing refused :/ which is how we ended up with
mul_u32_u32() in asm.