MS/CW-style inline assembly for GCC

[Robert Dewar]

> Is this really true?  What about the simple case of unlimited-
> precision addition on a processor which has a carry flag?  Do we
> expect the compiler to be smart enough to turn a loop like
>   c = 0;
>   for (i = 0; i < len; i++)
>     {
>       r[i] = a[i] + b[i] + c;
>       c = (int) (((long long) a[i] + (long long) b[i]) >> 32);
>     }
> into code which uses the "add with carry" instruction?
> 
> Sure, there is no algorithmic advantage.  But the code in assembler
> will be at least twice as fast.

Not only will the ASM code be twice as fast, but it will be much
clearer than C code.

Of course it is always possibloe to have the compiler have enough
smarts to handle one particular case like this correctly :-)