Hi,
On 2024-02-07 19:52:11 -0600, Nathan Bossart wrote:
> On Wed, Feb 07, 2024 at 04:42:07PM -0800, Andres Freund wrote:
> > On 2024-02-07 16:21:24 -0600, Nathan Bossart wrote:
> >> The assembly for that looks encouraging, but I still need to actually test
> >> it...
> >
> > Possible. For 16bit upcasting to 32bit is clearly the best way. For 32 bit
> > that doesn't work, given the 32bit return, so we need something more.
>
> For the same compASC() test, I see an ~8.4% improvement with your int64
> code
Just to be clear, that code unfortuntely isn't correct, the return value is a
32 bit integer, so the 64bit difference doesn't help. In contrast to the 16bit
case.
> and a ~3.4% improvement with this:
I guess that's still something.
Another branchless variant is (a > b) - (a < b). It seems to get a similar
improvement as the overflow-checking version.
Greetings,
Andres Freund