Any usable SIMD implementation?

[Marco Leise via Digitalmars-d]

Am Tue, 12 Apr 2016 23:22:37 -0700
schrieb Walter Bright <newshound2 at digitalmars.com>:

> >            "mulq %[y]"
> >            : "=a" tmp.lo, "=d" tmp.hi : "a" x, [y] "rm" y;  
> 
> I don't see anything elegant about those lines, starting with "mulq" is not in 
> any of the AMD or Intel CPU manuals. The assembler should notice that 'y' is a 
> ulong and select the 64 bit version of the MUL opcode automatically.
> 
> I can see nothing to recommend the:
> 
>      "=a" tmp.lo
> 
> syntax. How about something comprehensible like "tmp.lo = EAX"? I bet people 
> could even figure that out without consulting stackoverflow! :-)
> 
> I have no idea what:
> 
>     "a" x
> 
> and:
> 
>      [y] "rm" y
> 
> mean, nor why the ":" appears sometimes and the "," other times.

Tell me again, what's more elgant !

        uint* pnb = cast(uint*)cf.processorNameBuffer.ptr;
        version(GNU)
        {
            asm { "cpuid" : "=a" pnb[0], "=b" pnb[1], "=c" pnb[ 2], "=d" pnb[ 3] : "a" 0x8000_0002; }
            asm { "cpuid" : "=a" pnb[4], "=b" pnb[5], "=c" pnb[ 6], "=d" pnb[ 7] : "a" 0x8000_0003; }
            asm { "cpuid" : "=a" pnb[8], "=b" pnb[9], "=c" pnb[10], "=d" pnb[11] : "a" 0x8000_0004; }
        }
        else version(D_InlineAsm_X86)
        {
            asm pure nothrow @nogc {
                push ESI;
                mov ESI, pnb;
                mov EAX, 0x8000_0002;
                cpuid;
                mov [ESI], EAX;
                mov [ESI+4], EBX;
                mov [ESI+8], ECX;
                mov [ESI+12], EDX;
                mov EAX, 0x8000_0003;
                cpuid;
                mov [ESI+16], EAX;
                mov [ESI+20], EBX;
                mov [ESI+24], ECX;
                mov [ESI+28], EDX;
                mov EAX, 0x8000_0004;
                cpuid;
                mov [ESI+32], EAX;
                mov [ESI+36], EBX;
                mov [ESI+40], ECX;
                mov [ESI+44], EDX;
                pop ESI;
            }
        }
        else version(D_InlineAsm_X86_64)
        {
            asm pure nothrow @nogc {
                push RSI;
                mov RSI, pnb;
                mov EAX, 0x8000_0002;
                cpuid;
                mov [RSI], EAX;
                mov [RSI+4], EBX;
                mov [RSI+8], ECX;
                mov [RSI+12], EDX;
                mov EAX, 0x8000_0003;
                cpuid;
                mov [RSI+16], EAX;
                mov [RSI+20], EBX;
                mov [RSI+24], ECX;
                mov [RSI+28], EDX;
                mov EAX, 0x8000_0004;
                cpuid;
                mov [RSI+32], EAX;
                mov [RSI+36], EBX;
                mov [RSI+40], ECX;
                mov [RSI+44], EDX;
                pop RSI;
            }
        }

-- 
Marco