Re: [Qemu-devel] [PATCH 4/4] target/mips: Fix insert.<b|h|w> for MIPS big endian host

[Aleksandar Markovic]

> >> @@ -1511,9 +1518,11 @@ void helper_msa_insert_df(CPUMIPSState *env, 
> >> uint32_t df, uint32_t wd,
> >>       case DF_WORD:
> >>           pwd->w[n] = (int32_t)rs;
> >>           break;
> >> +#ifdef TARGET_MIPS64
> >>       case DF_DOUBLE:
> >>           pwd->d[n] = (int64_t)rs;
> >>           break;
> >> +#endif
> >>       default:
> >>           assert(0);
> >>       }
> > You are right that this case should be under ifdef the way you did.
> >
> > In fact, this code should be impossible to reach, since there is a check
> > for MIPS32/64 in translate.c before invoking this helper, so technically
> > there is no bug. However, it is a latent bag, and also an instance of
> > "dead code" (for MIPS32). So, you are rightfully removing this case
> > for MIPS32.
> >
> > May I just ask you to put this in a separate patch, since this has nothing
> > to do with endianess etc. (with the title, let's say:
> >
> > "target/mips: Remove handling of nonexistent flavor of INSERT for MIPS32",
> >
> > and the commit message
> >
> > "INSERT.D is present in MIPS64 MSA only. [1] page <XXX>
> >
> > [1] <insert here the latest MSA MIPS64 doc>"
> >
> > )?
> You are right, it has nothing to do with the endianness problem. I will
> remove that in v2, and add another patch for that.


Mateja, I noticed that FILL.D has almost identical problem.

Could you create a separate patch for FILL.D too, dealing with the same
issue?

And also analyze all MIPS64-only MSA instructions in this regard?

Glancing at the MIPS64 MSA doc, they are:

COPY_S.D
COPY_U.W (this is not a typo, it is W, not D)
FILL.D
INSERT.D

Yours,
Aleksandar

> >
> > Thanks,
> > Aleksandar
> Thanks,
> Mateja