Re: [Qemu-devel] [Consult] tilegx: About floating point instructions

[Chen Gang]

On 8/18/15 05:43, Richard Henderson wrote:
> 
> I repeat: This is an extremely bad idea.
> I will certainly not sign off on any patch that includes this.
> 

OK. At least it is not the professional implementation. But for me, it
can always get the correct result:

 - It 'guess' the 'flag' format instead of 'guess' whole data format,
   so this is an easier way (although it wastes resources, and it is
   UN-professional).

 - The 'flag' has 'room' for callee to save its information, so we can
   use the 'room' for recognizing each different 'flag' type (so we can
   treat 'flag' as callee's context).

 - The caller must keep the 'flag' consistent for all floating point
   insns. So if caller finds new using way (it is almost impossible),
   our implementation can still adapt the new using way, automatically.

If it is really can always get the correct result (else I have to
implement with your suggested way, right now):

 - I can use it for gcc testsuite (now, it fixed 100+ gcc testsuite
   failures -- I guess, all floating point tests are passed test).

 - And within this month, I shall try to finish gcc testsuite with qemu
   in my free time (still 700- issues left), and also make patches for
   kernel mm for learning (may be helpful for softmmu linux user).

 - Next month (after finish gcc testsuite with tilegx qemu), I shall
   implement the floating point in the preciser ways (you suggested),
   instead of current temporary implementation.

By the way, I have delay quite much for Linux kernel and gcc in my free
time:

 - Originally, I want to cross compile kernel under another archs in my
   free time within this month, but until now, I do nothing for it (but
   next, I shall try some mm patches instead of, hope I can succeed).

 - Originally, I want to fix one gcc bug under bugzilla, but until now,
   I do nothing for it (it is really delayed quite too much).


Welcome any ideas, suggestions and completions.


Thanks.
-- 
Chen Gang

Open, share, and attitude like air, water, and life which God blessed