Re: Computer architects leaving Intel...

On 9/2/2024 8:47 PM, MitchAlsup1 wrote:

On Mon, 2 Sep 2024 19:32:23 +0000, BGB wrote:
 

On 9/1/2024 6:32 PM, MitchAlsup1 wrote:

>
More modern machines have RND nobody will ever have REM.

>
Which is probably not a lot, as off-hand I am not aware of many ISA's
that have floor/ceil/round in the ISA itself, rather than doing it via
conversion to an integer type.

 VAX has round float* to float* 1978.....

So, there is this, and FRNDINT in x87.
Looks like there is ROUNDPS and ROUNDPD in SSE4.1, ...
I missed these as apparently my copies of the Intel docs were too old (only covering SSE2).
Looks like VRINT in ARMv8.
So, it seems I can find more examples than I thought...
I guess it is a question how often these are needed. As described in ARM's VRINT, it could allow doing floor() or ceil() in a single instruction. Not sure how much it would save as I don't expect floor/ceil to be common enough to justify this.
Could almost add this if needed, possibly as a hack to the usual Float->Int conversion process.