[llvm-commits] [PATCH, RFC] Medium code model support for 64-bit PowerPC

[Bill Schmidt]

Thanks, Uli, that makes good sense.  Much simpler your way.

Attached is a revised version of the patch along the lines you suggest.

Thanks,
Bill

On Mon, 2012-11-26 at 16:09 +0100, Ulrich Weigand wrote:
> Bill Schmidt <wschmidt at linux.vnet.ibm.com> wrote:
> 
> > Here's a new revision of the patch.  The changes are:
> >
> > (1) Add support for direct object file writing:
> >  - New relocation types in ELF.h.
> >  - New fixup kinds in PPCFixupKinds.h
> >  - Handle new fixups in PPCMCCodeEmitter.cpp, PPCAsmBackend.cpp, and
> > PPCELFObjectWriter.cpp.
> 
> I think this may be a bit overkill; I don't think you need new fixups
> (I see you followed the existing precedent of fixup_ppc_toc16 and
> fixup_ppc_toc16_ds, but I think those are already unnecessary).
> 
> The *fixup* type describes *how* a value is to be inserted into an
> instruction; this is the same for the TOC variants.  The difference
> is only which *value* is to be inserted, and that is (supposed to
> be) already encoded in the symbol kind.
> 
> PPCELFObjectWriter::getRelocTypeInner is then supposed to consult
> the pair of fixup type and symbol kind to choose the appropriate
> relocation type.  So instead of adding something like:
> 
> +    case PPC::fixup_ppc_toc16_lo:
> +      Type = ELF::R_PPC64_TOC16_LO;
> +      break;
> 
> I think you should rather add a check of symbol kind under the
> existing PPC::fixup_ppc_lo16 case.  (Similar to what I did for
> TPREL16_LO.)
> 
> Bye,
> Ulrich
> 

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