On Aug 2, 2010, at 8:08 PM, Timothy M Jones wrote:

> Hi everyone,
> 
> On 18/07/2010 10:46, Korey Sewell wrote:
>> 
>>    That seems odd... I assume you're suggesting that Tim switch the
>>    InOrderCPU to pass the PC instead, right?
>> 
>> Yep, I'm suggesting that this should be updated.
>> 
>> Tim, you'll want to edit the code fetch_seq_unit.cc, execution_unit.cc,
>> and branch_predictor.cc to make sure that the PC gets passed throughout
>> instead of the nextPC.
>> 
> I was just updating this patch and remembered this discussion.  Then I 
> checked the code and found that O3CPU is also passing the next PC into the 
> branch predictor.  It's a little unclear about what is expected in the branch 
> predictor code.  This parameter is altered to pass back the branch target, so 
> sending in the initial next PC seems reasonable.  On the other hand, it's 
> used as the actual PC for the RAS and BTB so should really be that.  This 
> could also explain why the original code was using inst->readPC() for the 
> DPRINTFs.
> 
> Shall I fix up the interface so it's a little more clear what's required and 
> alter both CPUs to pass in the current PC, not next PC?
> 
> Cheers
> Tim
Don't we want to pass both the PC and the next PC then? The latter being for 
the RAS?

Ali

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