Benchmark memchar (with GCC builtins)

[Iakh via Digitalmars-d]

On Friday, 30 October 2015 at 21:33:25 UTC, Andrei Alexandrescu 
wrote:
> Could you please take a look at GCC's generated code and 
> implementation of memchr? -- Andrei

So i did. I rewrite code to do main work in cacheLineSize chunks. 
And this
is what GLIBC version do.
So main loop looks this:

-----
     do
     {
         // ptr16 is aligned 64
         ubyte16 r1 = __builtin_ia32_pcmpeqb128(ptr16[0], niddles);
         ubyte16 r2 = __builtin_ia32_pcmpeqb128(ptr16[1], niddles);
         ubyte16 r3 = __builtin_ia32_pcmpeqb128(ptr16[2], niddles);
         ubyte16 r4 = __builtin_ia32_pcmpeqb128(ptr16[3], niddles);

         r3 = __builtin_ia32_pmaxub128(r1, r3);
         r4 = __builtin_ia32_pmaxub128(r2, r4);
         r4 = __builtin_ia32_pmaxub128(r3, r4);
         mask = __builtin_ia32_pmovmskb128(r4);

         if (mask != 0)
         {
             mask = __builtin_ia32_pmovmskb128(r1);
             mixin(CheckMask); // Check and return value

             ++ptr16; num -= 16;
             mask = __builtin_ia32_pmovmskb128(r2);
             mixin(CheckMask);

             ++ptr16; num -= 16;
             r3 = __builtin_ia32_pcmpeqb128(*ptr16, niddles);
             mask = __builtin_ia32_pmovmskb128(r3);
             mixin(CheckMask);

             ++ptr16; num -= 16;
             r4 = __builtin_ia32_pcmpeqb128(*ptr16, niddles);
             mask = __builtin_ia32_pmovmskb128(r4);
             mixin(CheckMask);
         }

         num -= 64;
         ptr16 += 4;
     }
     while (num > 0);
-----

and my best result:

-----
Naive:        21.46 	TickDuration(132842482)
SIMD:         1.161 	TickDuration(7188211)
(was)SIMD:     3.04     TickDuration(18920182)
C:                1 	TickDuration(6189222)