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Re: [PATCH, PowerPC] Fix PR57949 (ABI alignment issue)
- From: Alan Modra <amodra at gmail dot com>
- To: Andrew Haley <aph at redhat dot com>
- Cc: Bill Schmidt <wschmidt at linux dot vnet dot ibm dot com>, gcc-patches at gcc dot gnu dot org, libffi-discuss at sourceware dot org, dje at gcc dot gnu dot org
- Date: Tue, 17 Sep 2013 09:08:49 +0930
- Subject: Re: [PATCH, PowerPC] Fix PR57949 (ABI alignment issue)
- Authentication-results: sourceware.org; auth=none
- References: <1376494321 dot 17852 dot 17 dot camel at oc8801110288 dot ibm dot com> <20130911113845 dot GF2643 at bubble dot grove dot modra dot org> <1378904143 dot 3730 dot 46 dot camel at gnopaine> <20130912021149 dot GG2643 at bubble dot grove dot modra dot org> <52317C41 dot 8070303 at redhat dot com>
On Thu, Sep 12, 2013 at 09:33:05AM +0100, Andrew Haley wrote:
> On 09/12/2013 03:11 AM, Alan Modra wrote:
> > We have precedent for compiling libffi based on gcc preprocessor
> > defines, eg. __NO_FPRS__, so here's a way of making upstream libffi
> > compatible with the various versions of gcc out there. I've taken the
> > condition under which we align aggregates from
> > rs6000_function_arg_boundary, and defined a macro with a value of the
> > maximum alignment.
>
> I would have thought that a runtime or configure-time test in libffi
> would be better.
I don't see how a runtime check can be done, and a configure test just
adds another layer of indirection. How is testing a cpp macro at
configure time better than testing the same at compile time?
--
Alan Modra
Australia Development Lab, IBM