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

[Aleksandar Markovic]

> From: Mateja Marjanovic <address@hidden>
> Subject: [PATCH 4/4] target/mips: Fix insert.<b|h|w> for MIPS big endian host
> 
> From: Mateja Marjanovic <address@hidden>
> 
> Inserting from GPR to an element in a MSA register when
> executed on a MIPS big endian CPU, didn't pick the
> right element, and was behaving like on little endian.
> 
> Signed-off-by: Mateja Marjanovic <address@hidden>
> ---

...

> @@ -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>"

)?

Thanks,
Aleksandar