[Libre-soc-bugs] [Bug 1068] add instructions from ls012 not currently implemented in binutils

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=1068

--- Comment #42 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
(In reply to Dmitry Selyutin from comment #41)
> The instructions are synced:
> https://git.libre-soc.org/?p=binutils-gdb.git;a=commitdiff;
> h=323e75a0215c2b3da2d97ee6024797d04a9e1385
> 
> Due to time and budget constraints, I've put this sync into a single commit
> and left tests out of it. Considering the previous changes already done in
> the scope of this task, I hope nobody objects if other activities are
> performed in the scope of the new tasks.

not at all.

> I found it extremely annoying to add aliases for minmax and fminmax

they weren't on the TODO list in comment #0 so should not have been added.

the reason is (as you noted above) there's no unit tests... because
*pypowersim* does not support aliases, therefore we cannot even test
them (as part of openpower-isa unit tests).

> much time, but highly error-prone). Any objections if I raise the task for
> introducing a special format for aliases?

none at all - please cross-reference it ("See also") to this bugreport
and put it on "Future" milestone. when we come to putting in *another*
NLnet Grant, the list can be reviewed and it not forgotten.

also i cannot explain why but there are reasons (confidential to the ISA WG)
why adding aliases should be delayed until an announcement is made by the
ISA WG. (i am NOT authorized to give out OPF confidential information but
i can at least say "i am not authorized but there are reasons").


> I remember a discussion where Luke
> pointed that we were not ready for aliases,

correct. below explains why.

> but it's the second time I've
> added these. :-)

if they cannot be tested (no openpower-isa unit tests, rather than
binutils tests) then many apologies but they need to be removed
(from this patch, as they were never to be part of this task).

when *another* NLnet Grant is done (which we can only do when at least
one of these outstanding ones is completed) *then* we can look at:

1) define the aliases format
2) define a *database* format for them and implement them in insndb
3) add aliases in pypowersim
4) UNIT TESTS for aliased instructions in openpower-isa and FINALLY - ONLY
THEN:
5) adding binutils support for the same aliases AND THEN
6) add unit tests for the same aliases in binutils AND THEN
7) run the same unit tests for openpower-isa but using binutils

which is about... a minimum of... EUR 15,000 worth of additional
work that is *not* accounted for in *any* of the current EUR 300,000 of
NLnet grants?

i trust that this is now really clear that aliases were not, shall not, cannot
and will NEVER be part of the *current* scope of work within at least the
next 4-6 months, until we have completed sufficient of the EUR **300,000**
worth of existing outstanding uncompleted NLnet grants, to be able to put
in another one?

(as you can see i am able to think in terms of breaking tasks down to this
level where time and budget can be allocated to them within reasonable
estimates. Jacob is *not* capable of doing that: he will add "and this
needs doing. and that's a good idea. and this other thing needs to be
done" - in one extreme case a task allocated to him with a 10 day budget
i let him get on with it for 5 *months* before reminding him that the
budget was 10 days and he hadn't done *any* of what was actually
required for the actual payment from NLnet - to teach him the hard
lesson that he needs to learn about focus, time, scoping, and budget
management.

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