[llvm] r193742 - [SystemZ] Automatically detect zEC12 and z196 hosts

[Ulrich Weigand]

Richard Sandiford <rsandifo at linux.vnet.ibm.com> wrote on 31.10.2013
14:15:01:

> Yeah, I thought about doing that, but I don't think it's necessary.
> If IBM uses sensible numbering for future architectures -- and (looks at
> pay cheque) I'm sure they will -- then matching ranges means we get the
> benefit of zEC12 features automatically.  If for some reason the machine
> numbers go down, the worst that will happen is that we'll unnecessarily
> pick an older architecture instead.  Whereas if we only match the numbers
> we know about, we'll _always_ get the oldest architecture (z10 in our
case)
> for new machines.

So what I would have suggested is:
- If the number matches a machine we support (z10, z196, zEC12),
  set the architecture accordingly.
- Otherwise, if the number matches a known old machine (pre-z10,
  S/390, ...), either set architecture to z10, or maybe better,
  error out with "unsupported machine type"
- Otherwise, assume we have a future machine and default to the
  latest model we support (i.e. zEC12)

Bye,
Ulrich