[libre-riscv-dev] daily kan-ban update, 22jul2020

[libre-riscv-dev] daily kan-ban update, 22jul2020

[Jacob Lifshay]

today:
still working on Div FSM -- I think it's complete (except for not
supporting cancellation), but didn't thoroughly test it yet. In the
process of refactoring test_pipe_caller.py into a easier-to-test shape
and adding parallel test cases for DivPipeCore, FSMDivCore, and
SimOnly, I discovered that for test_divwuo_regression_1 (0xc4e32b68 /
0x32867d69), the pipeline (SimOnly) is giving the correct results
(rt=0x3), it's the ISA simulator code that's messed up
(rt=0xFFFFFFFF).

Luke (or whoever is more familiar with it), I'll let you figure out
how to fix the ISA simulator.

Jacob

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Re: [libre-riscv-dev] daily kan-ban update, 22jul2020

[Cole Poirier]

Today:

* Finished coriolis2-chroot setup script, it's tested and works correctly!
* Finished updating the wiki libreriscv/HDL_workflow/coriolis2
documentation to sync it with the coriolis-chroot setup script

I can't push my commit to the libreriscv repo, can you please grant me
access Luke?

Cole

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Re: [libre-riscv-dev] daily kan-ban update, 22jul2020

[Luke Kenneth Casson Leighton]

On Thursday, July 23, 2020, Jacob Lifshay <programmerjake@gmail.com> wrote:

> today:
> still working on Div FSM -- I think it's complete (except for not
> supporting cancellation), but didn't thoroughly test it yet. In the
> process of refactoring test_pipe_caller.py into a easier-to-test shape
> and adding parallel test cases for DivPipeCore, FSMDivCore, and
> SimOnly, I discovered that for test_divwuo_regression_1 (0xc4e32b68 /
> 0x32867d69), the pipeline (SimOnly) is giving the correct results
> (rt=0x3), it's the ISA simulator code that's messed up
> (rt=0xFFFFFFFF).


please raise a bugreport for it.


>
> Luke (or whoever is more familiar with it), I'll let you figure out
> how to fix the ISA simulator.


it's running the pseudocode.  if the pseudocode gives the wrong answer,
that's bad.

what happens when testing the same values in simulator/test_div_dim.py?

hm wait you can't put initial regs into qemu yet.  been meaning to add that.

l.



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Re: [libre-riscv-dev] daily kan-ban update, 22jul2020

[Luke Kenneth Casson Leighton]

On Thursday, July 23, 2020, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
wrote:

>
>
> On Thursday, July 23, 2020, Jacob Lifshay <programmerjake@gmail.com>
> wrote:
>
>>
>> SimOnly, I discovered that for test_divwuo_regression_1 (0xc4e32b68 /
>> 0x32867d69), the pipeline (SimOnly) is giving the correct results
>> (rt=0x3), it's the ISA simulator code that's messed up
>> (rt=0xFFFFFFFF).
>
>
> please raise a bugreport for it.
>

saw it, thank you for doing that.

these look great btw


https://git.libre-soc.org/?p=soc.git;a=commitdiff;h=78096b62db0345846cca70ab2f75f9c3519006c4


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Re: [libre-riscv-dev] daily kan-ban update, 22jul2020

[Jacob Lifshay]

On Thu, Jul 23, 2020, 02:40 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
wrote:

> On Thursday, July 23, 2020, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
> wrote:
>
> >
> >
> > On Thursday, July 23, 2020, Jacob Lifshay <programmerjake@gmail.com>
> > wrote:
> >
> >>
> >> SimOnly, I discovered that for test_divwuo_regression_1 (0xc4e32b68 /
> >> 0x32867d69), the pipeline (SimOnly) is giving the correct results
> >> (rt=0x3), it's the ISA simulator code that's messed up
> >> (rt=0xFFFFFFFF).
> >
> >
> > please raise a bugreport for it.
> >
>
> saw it, thank you for doing that.
>
> these look great btw
>
>
>
> https://git.libre-soc.org/?p=soc.git;a=commitdiff;h=78096b62db0345846cca70ab2f75f9c3519006c4


Thanks! I used the same list of test values as in
power-instruction-analyzer.

Jacob
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Re: [libre-riscv-dev] daily kan-ban update, 22jul2020

[Luke Kenneth Casson Leighton]

On Thursday, July 23, 2020, Jacob Lifshay <programmerjake@gmail.com> wrote:

> On Thu, Jul 23, 2020, 02:40 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
> wrote:
>
> > On Thursday, July 23, 2020, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
> > wrote:
> >
> > >
> > >
> > > On Thursday, July 23, 2020, Jacob Lifshay <programmerjake@gmail.com>
> > > wrote:
> > >
> > >>
> > >> SimOnly, I discovered that for test_divwuo_regression_1 (0xc4e32b68 /
> > >> 0x32867d69), the pipeline (SimOnly) is giving the correct results
> > >> (rt=0x3), it's the ISA simulator code that's messed up
> > >> (rt=0xFFFFFFFF).
> > >
> > >
> > > please raise a bugreport for it.
> > >
> >
> > saw it, thank you for doing that.
> >
> > these look great btw
> >
> >
> >
> > https://git.libre-soc.org/?p=soc.git;a=commitdiff;h=
> 78096b62db0345846cca70ab2f75f9c3519006c4
>
>
> Thanks! I used the same list of test values as in
> power-instruction-analyzer.


i wondered if, like in the ieee754fp tests, if some random values could be
added, too.

also, some exponentially scaled numbers.

two random uniform distributed numbers for div, the answer pretty much
averages out to 1 which is of course a fairly useless test.

by doing this you get a much better distribution suited to testing divide
full range:

x = random(1,32)
return random(0,1<<x)

l.




> Jacob
> _______________________________________________
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> libre-riscv-dev@lists.libre-riscv.org
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>


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Re: [libre-riscv-dev] daily kan-ban update, 22jul2020

[Jacob Lifshay]

On Thu, Jul 23, 2020, 09:42 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
wrote:

> On Thursday, July 23, 2020, Jacob Lifshay <programmerjake@gmail.com>
> wrote:
>
> > On Thu, Jul 23, 2020, 02:40 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
> > wrote:
> >
> > > On Thursday, July 23, 2020, Luke Kenneth Casson Leighton <
> lkcl@lkcl.net>
> > > wrote:
> > >
> > > >
> > > >
> > > > On Thursday, July 23, 2020, Jacob Lifshay <programmerjake@gmail.com>
> > > > wrote:
> > > >
> > > >>
> > > >> SimOnly, I discovered that for test_divwuo_regression_1 (0xc4e32b68
> /
> > > >> 0x32867d69), the pipeline (SimOnly) is giving the correct results
> > > >> (rt=0x3), it's the ISA simulator code that's messed up
> > > >> (rt=0xFFFFFFFF).
> > > >
> > > >
> > > > please raise a bugreport for it.
> > > >
> > >
> > > saw it, thank you for doing that.
> > >
> > > these look great btw
> > >
> > >
> > >
> > > https://git.libre-soc.org/?p=soc.git;a=commitdiff;h=
> > 78096b62db0345846cca70ab2f75f9c3519006c4
> >
> >
> > Thanks! I used the same list of test values as in
> > power-instruction-analyzer.
>
>
> i wondered if, like in the ieee754fp tests, if some random values could be
> added, too.
>

I specifically want the test cases to be reproducible for
power-instruction-analyzer, since the test results generated on a POWER9
cpu are checked into the repo for those who don't have a POWER9.

for soc, we can copy the test case generation logic from DivPipeCore's
tests in ieee754fpu since that covers waaay more cases (nicely
exponentially distributed too) but is also deterministic. it covers the
cases:
for all 0 <= a < 2^8 and 0 <= b < 64:
the case a << b if b < 64 - 8
and the case ~(a << b) if b < 64 - 8
and the case (1 << b) - 1
and the case ~((1 << b) - 1)

It might use a different value than 8 -- icr.

this covers all the corner cases I can think of, which random testing has a
very small chance of ever hitting (small enough that you'd need every
person on the planet to all run the test on the order of a billion times
each to hit the case once).

Jacob
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Re: [libre-riscv-dev] daily kan-ban update, 22jul2020

[Luke Kenneth Casson Leighton]

On Thursday, July 23, 2020, Jacob Lifshay <programmerjake@gmail.com> wrote:

>
> for soc, we can copy the test case generation logic from DivPipeCore's
> tests in ieee754fpu since that covers waaay more cases (nicely
> exponentially distributed too) but is also deterministic. it covers the
> cases:
> for all 0 <= a < 2^8 and 0 <= b < 64:
> the case a << b if b < 64 - 8
> and the case ~(a << b) if b < 64 - 8
> and the case (1 << b) - 1
> and the case ~((1 << b) - 1)


ohh yeh i remember now.



> It might use a different value than 8 -- icr.
>
> this covers all the corner cases I can think of, which random testing has a
> very small chance of ever hitting


yehyeh this is why the ieee754fp tests have to have special cornercase
handling, zero, inf, nan etc.

(small enough that you'd need every
> person on the planet to all run the test on the order of a billion times
> each to hit the case once).


:)

we need a way to express these, cross language, so that they can be run in
multiple scenarios.

qemu, pia, ISACaller, HDL.

l.



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