On 07/13/2017 11:32 AM, Jakub Jelinek wrote: > On Thu, Jul 13, 2017 at 11:28:17AM -0600, Jeff Law wrote: >> On 07/12/2017 04:44 PM, Segher Boessenkool wrote: >>> On Tue, Jul 11, 2017 at 03:19:36PM -0600, Jeff Law wrote: >>>> Examples of implicit probes include >>> >>>> 2. ABI mandates that *sp always contain a backchain pointer (ppc) >>> >>> In the ELFv2 ABI a backchain is not required. GCC still always has >>> one afaik. I'll find out more. >> Please do. I was under the impression it was mandated by the earlier >> ABIs as well. If it isn't, then I don't think we can depend on it for >> the older ABIs. >> >> That wouldn't be the end of the world -- it's pretty clear that ppc64le >> is the future and we'd get good code there. I wouldn't lose much sleep >> if ppc32 and ppc64 big endian had a less efficient probing scheme. > > ?? Segher said in ELFv2 ABI it is not required, so that would mean > it does affect ppc64le and does not affect ppc32 or ppc64. > So, we wouldn't get good code for ppc64le and would get one for ppc32 and > ppc64. Opps. Mis-read. Got it totally backwards
Not good. Waiting on Segher for clarification, but will start thinking about better options than punting :-) jeff
