Re: Computer architects leaving Intel...

On 05/09/2024 23:39, Scott Lurndal wrote:

Bernd Linsel <bl1-thispartdoesnotbelonghere@gmx.com> writes:

On 05.09.24 19:04, Terje Mathisen wrote:

One of my alternatives are
>
   unsigned u = start; // Cannot be less than zero
   if (u) {
      u++;
      do {
         u--;
         data[u]...
      while (u);
    }
>
This typically results in effectively the same asm code as the signed
version, except for a bottom JGE (Jump (signed) Greater or Equal instead
of JA (Jump Above or Equal, but my version is far more verbose.
>
Alternatively, if you don't need all N bits of the unsigned type, then
you can subtract and check if the top bit is set in the result:
>
  %G�%@|  for (unsigned u = start; (u & TOPBIT) == 0; u--)
>
Terje
>

>
What about:
>
for (unsigned u = start; u != ~0u; --u)

 This is the form we use most when we need
to work in reverse.
 

In a code review, I would reject that - and all the other nonsenses suggested here as a way to force all loop indices to be unsigned types as though that rule was the 11th commandment.
Just write code that makes sense - it's /not/ hard in this case!
for (int i = start; i >= 0; i--) ...
If you need the loop counter to be an unsigned type inside the loop code, make an unsigned version:
for (int i = start; i >= 0; i--) {
const unsigned int u = i;
...
}
Sometimes it amazes me the kind of nonsense people write in code because of obsession about particular rules.  Code clarity trumps /all/ stylistic rules.