[gmx-developers] mknb doesn't work on BlueGene with --enable-ppc-sqrt in single precision
Mark.Abraham at anu.edu.au
Thu Sep 3 01:24:43 CEST 2009
After "./configure --enable-ppc-sqrt" on BlueGene, mknb is called with
-ppc_sqrt. In ppc_invsqrt(), mknb_innerloop.c generates code to call to
__frsqrtes. That might be sound on other PPC architectures, but BlueGene
doesn't do single-precision arithmetic, so this built-in does not exist.
To work-around, do not specify --enable-ppc-sqrt in single precision on
To fix, we would still prefer to use the PPC inverse square root in all
cases. We need to call a double-precision version on BlueGene, and not
on others. That suggests mknb_innerloop.c needs to #include <config.h>
(which is on the search path) and use #ifdef GMX_BLUEGENE.
(If Bugzilla was working, I'd have filed this and various others of my
reports on Bugzilla. How do we make sure these get dealt with for any
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