[Info-vax] NaT consumption faults with COBOL?

[John Reagan]

"JF Mezei" <jfmezei.spamnot 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