Re: Optimization problem: bulk Boolean operations on vectors

[hardreset via Digitalmars-d]

On Friday, 23 December 2016 at 16:15:44 UTC, Andrei Alexandrescu 
wrote:
An interesting problem to look at:

https://github.com/dlang/dmd/pull/6352
Andrei

Ok some hand written assembler to and-assign ints...

enum SIZE = 100000000;

void foo3(int* a, int* b)
{
    asm
    {
        mov   EAX,a;
        mov   EDX,b;
        sub   EDX,EAX;
        mov   ECX,EAX;
        add   ECX,SIZE*4;
    l1:;
        cmp   EAX,ECX;
        jae   done;
        mov   EBX,[EAX];
        and   EBX,[EAX+EDX];
        mov   [EAX],EBX;
        add   EAX,4;
        jmp l1;
    done:;
    }
}

I get..

456ms for unconditional
505ms for conditional
268ms for assembler

So the asm is about 40% faster than the best of the alternatives. 
The point being that it's the generated code not the source 
that's the problem.