[Info-vax] NaT consumption faults with COBOL?

[IanMiller]

On 20 Nov, 02:04, "John Reagan" <johnrrea... at earthlink.net> wrote:
> "JF Mezei" <jfmezei.spam... at vaxination.ca> wrote in message
>
> news:00fef009$0$23230$c3e8da3 at news.astraweb.com...
>
>
>
> > Perhaps they should have added an instruction that clears all
> > speculative bits in all registers, and this could be called before and
> > after calling any subroutine.
>
> Well then you'd have no preserved state registers across a routine call.
>
> And there are instructions to load/save the entire set of NaT bits.  They
> live in their own application register with special instructions to access
> them.  They need to be saved/restore at context swaps, interrupts, etc.  The
> problem is that they are pretty slow instructions since they interrupt the
> pipeline/parallel execution nature of the chip.
>
> Same issue with the setf.sig/getf.sig instructions which move integer
> registers to/from the 64-bit mantissa of the floating registers.  They are
> used quite a bit, but they are slow since it forces the integer unit on the
> chip to start talking to the floating unit on the chip.  They have different
> number of pipeline stages.
>
> John


All of which demonstrates things are even weirder than they first
appear, even for the Itainium architecture which is very strange in
places.