[Info-vax] Microsoft: Alpha architecture responsible for poor Windows file compression

[Bob Gezelter]

On Wednesday, November 2, 2016 at 9:59:06 AM UTC-4, Simon Clubley wrote:
> According to:
> 
> http://www.theregister.co.uk/2016/11/02/ghost_of_dec_alpha_sees_microsoft_dumb_down_windows_file_compression/
> 
> Microsoft are saying that limits in the Alpha architecture are responsible
> for poor Windows file compression in today's world. Sample quote:
> 
> |Chen says one of his "now-retired colleagues worked on real-time compression,
> |and he told me that the Alpha AXP processor was very weak on bit-twiddling
> |instructions. For the algorithm that was ultimately chosen, the smallest unit
> |of encoding in the compressed stream was the nibble; anything smaller would
> |slow things down by too much. This severely hampers your ability to get good
> |compression ratios."
> 
> Do any Alpha architecture experts here know if this is the full story ?
> 
> Simon.
> 
> -- 
> Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
> Microsoft: Bringing you 1980s technology to a 21st century world

Simon,

I would want to see the details on that claim. As an attorney (or barrister) would say, "Objection. Hearsay."

Having written a compiler backend, my "rubbish" alarm goes off at that statement. Certainly, as the MACRO-64 level, there should be no problems. If the statement was "the MS compiler did not produce good code", I would be less critical.

If one is a good developer at that level, there is no problem. If you are trying to take a piece of code written for x86 (of that day) and translate it one-for-one, I would not take any bets.

Written correctly, such code should be no problem on Alpha, particularly due to Alpha's larger register set.

- Bob Gezelter, http://www.rlgsc.com