Korey Sewell wrote:
> Hi Rick,
>
>     (2) The hw_mfpr and hw_mtpr instructions cause a serialization
>     stall in
>     the O3 pipeline. Based on comments from rename_impl.hh (pasted below),
>     it appears that these serializations are not strictly necessary, but
>     based on limited support. Does someone know how I could could go about
>     enabling support to allow the hw_mfpr and hw_mtpr instructions execute
>     out of order?
>
> If you are convinced those instructions do not nee to be executed 
> serially, then I would hypothesize first to remove the "IsSerializing" 
> flag on the instruction defintion (arch/alpha/isa/decoder.isa) and all 
> should be OK.
>
> I assume that the those instructions hit registers in the 
> "miscellaneous" register file and hence dont necessarily get renamed 
> since that would be modifying system state. But in your case, it 
> sounds like you want those registers to be renamed and continue to 
> execute so a solution *might* be to allow those registers to be 
> renamed by adding an additional renaming check in rename_impl.hh or 
> scoreboard.hh or whatever exact file is checking to see if 
> int/fp/misc. registers need to be renamed.
>
> I hope that helps (if I'm understanding your problem correctly)...
>
> - Korey
That definitely helps.


-Rick

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