MC parser and PPC variants on constants

[Ulrich Weigand]

Joerg Sonnenberger <joerg at britannica.bec.de> wrote:
> On Sat, Jul 13, 2013 at 08:10:56PM +0200, Joerg Sonnenberger wrote:
> > PowerPC assembler supports expressions like "1234 at l". This doesn't with
> > MC right now, because the constant expression never reaches the target
> > layer. I wonder if it is really that useful to refactor this ATM,
> > especially since it likely makes sense to share the variant codes at
> > some point as many RISC platforms have similar needs in this area.
>
> New version with Target hook.

Thanks for working on this!

A couple of comments:

+  // XXX Duplicates MCTargetExpr::EvaluateAsRelocatableImpl

Now that this is PPC-specific code, we don't need to duplicate
this any more.  We can simply create an appropriate PPCMCExpr
here, and leave the evaluation of EvaluateAsRelocatableImpl
later.

+  switch (Variant) {
+  default:
+    llvm_unreachable("Invalid kind!");

Since this can be triggered by user input (e.g. 123 at got),
it should result in a regular error, not a failed assertion.


Bye,
Ulrich