It should work functionally. It's quite possible classifying
instructions like that in Power was left for after things worked
functionally and never revisited. This is almost certainly the case for
some of the other ISAs. You can attempt to change the isa description
yourself so that the right op class is used. Because the description is
built in a custom language it can be tricky to figure out what's going
on, but if Power is structured similar to Alpha then the op class
setting code may be pretty easy to port if it isn't in there already.
When you configure the functional unit in O3, don't change the file in
src/ since those files only set the default value. You'll want to
change
the value in the CPU you're instantiating in a configuration script.
That way you won't have to recompile M5 to try a new value.
Gabe
Sameh Galal wrote:
> Hi,
> I have a quick question about how PowerPC out of order cpu model in
SE
> mode. Is the out of order model fully supported in PowerPC
>
> The reason I am asking, is that it is not clear to me how the
> functional units of the PowerPC architecture are assigned their
> latencies. I found that the file src\cpu\o3\FuncUnitConfig.py
contains
> the functional unit configuration and which instructions the units
> handle. For example the FP_MultDiv unit handles the FloatMult
> instructions among other instructions
>
> class FP_MultDiv(FUDesc):
> opList = [ OpDesc(opClass='FloatMult', opLat=4),
> OpDesc(opClass='FloatDiv', opLat=12, issueLat=12),
> OpDesc(opClass='FloatSqrt', opLat=24, issueLat=24) ]
> count = 2
>
> However when I grep the source folder for FloatMult, I find that only
> the alpha architecture instruction decoder assigns the Opclass types.
> So how is the simulation of powerpc functional units done?
>
> [same...@cyclades-master m5]$ grep -r FloatMult ./src
> ./src/arch/alpha/isa/decoder.isa: 0x02: muls({{
> Fc = Fa * Fb; }}, FloatMultOp);
> ./src/arch/alpha/isa/decoder.isa: 0x02: muls({{
> Fc.sf = Fa.sf * Fb.sf; }}, FloatMultOp);
> ./src/arch/alpha/isa/decoder.isa: 0x22: mult({{
> Fc = Fa * Fb; }}, FloatMultOp);
> ./src/cpu/FuncUnit.py: 'FloatCmp', 'FloatCvt',
'FloatMult',
> 'FloatDiv', 'FloatSqrt',
> ./src/cpu/o3/FuncUnitConfig.py: opList = [
> OpDesc(opClass='FloatMult', opLat=4),
> ./src/cpu/op_class.hh:const OpClass FloatMultOp = Enums::FloatMult;
>
> Thanks for clarifying.
> Sameh
>
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