>Would that work?
Nope, I tried to address that question in a comment in the patch.
The link succeeds and the problem only occurs when the executable is RUN.
So one would need AC_TRY_RUN; and then one has openned the the
cross-compilation can-of-worms.
-Paul
On 2/1/2012 9:51 PM, Brice Goglin wrote:
We could also AC_TRY_LINK a program that uses ffsfoo (the one that
actually breaks here).
If it fails, we AC_TRY_LINK a program that uses ffsfoo with the
__ffssi2() definition.
If it fails, we define NEED_FFS_FIX
And we just add the fix under #ifdef NEED_FFS_FIX in private/misc.h.
Would that work?
thanks
Brice
Le 02/02/2012 02:28, Paul H. Hargrove a écrit :
On 2/1/2012 11:46 AM, Paul H. Hargrove wrote:
[snip]
So, in short: when building w/ this compiler, hwloc needs to behave
as if the system lacks ffs().
Making that happen is non-trivial because there are no preprocessor
symbols defined by gccfss that would allow compile-time #if checks
to distinguish gccfss from "vanilla" gcc. The only difference is in
the string value of __VERSION__, which one could check at configure
time.
Attached is a patch, relative to the svn trunk, which fixes this
problem in my testing.
As I outlined above, the approach is two-fold:
1) Add configure-time logic to ID the buggy compiler
2) Restructure include/private/misc.h to include a
HWLOC_HAVE_BROKEN_FFS case.
Two things I'd like to note about the approach:
+ The configure-time logic is NOT trying to determine the version
number, as I don't have a way (yet?) to pinpoint which version(s)
work correctly, and the Oracle Forums thread on the subject doesn't
say. So, it is conservatively assuming all "gccfss" versions are
broken.
+ The misc.h changes are intentionally "generic" so one could add
other configure time checks to define HWLOC_HAVE_BROKEN_FFS based on
problems we've not yet discovered.
-Paul
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Paul H. Hargrove phhargr...@lbl.gov
Future Technologies Group
HPC Research Department Tel: +1-510-495-2352
Lawrence Berkeley National Laboratory Fax: +1-510-486-6900
