TCE target nonconforming definition of long long and intmax_t

[Aaron Ballman via cfe-commits]

On Wed, Dec 8, 2021 at 2:20 AM Pekka Jääskeläinen
<pekka.jaaskelainen at tuni.fi> wrote:
>
> Hi Aaron,
>
> Indeed the 32b TCE target is not fully compliant in this aspect;
> its 64b emulation support is not complete, therefore we advertise
> only these 32b limits. We have an in-progress 64b target where the
> limits are 64b, but it's not upstreamed yet.
>
> Yes, TCE target is still maintained, but it's a special target since
> it has target-specific backend phases off-tree for online retargeting
> and pecularities of the TTA scheduling. Thus, I'd just leave it as
> is for the 32b target and we'll upstream the 64b stub as soon as
> it stabilizes a bit.

Okay, that sounds like a sensible approach to me.

~Aaron

>
> BR,
> Pekka
>
> On 7.12.2021 16.59, Aaron Ballman wrote:
> > Hello! I was digging around in stdint.h to do some implementation work
> > on C2x and I noticed that the TCE target seems to be nonconforming.
> >
> > In C17, the implementation limits for intmax_t and uintmax_t are
> > specified by 7.20.2.5 as:
> >
> > — minimum value of greatest-width signed integer type
> > INTMAX_MIN -(2^63 - 1)
> > — maximum value of greatest-width signed integer type
> > INTMAX_MAX 2^63 - 1
> > — maximum value of greatest-width unsigned integer type
> > UINTMAX_MAX 2^64 - 1
> >
> > Similarly, the implementation limits for long long and unsigned long
> > long are specified by 5.2.4.2.1p1:
> >
> > minimum value for an object of type long long int
> > LLONG_MIN -9223372036854775807 // -(2^63 - 1)
> > — maximum value for an object of type long long int
> > LLONG_MAX +9223372036854775807 // 2^63 - 1
> > — maximum value for an object of type unsigned long long int
> > ULLONG_MAX 18446744073709551615 // 2^64 - 1
> >
> > However, the TCE target appears to set these to 32-bit limits, not
> > 64-bit limits:
> >
> > https://github.com/llvm/llvm-project/blob/2ab513cd3e0648806db7ed1f8170ad4a3d4e7749/clang/lib/Basic/Targets/TCE.h#L61
> >
> > Is this target still being maintained? If so, what should be done
> > here? (I can file a bug report about this once we have a bug database
> > that can accept new content so we don't lose track of this.)
> >
> > Thanks!
> >
> > ~Aaron
> >
>
> --
> Pekka