Dear libMesh developers,
I'm having some troubles compiling libMesh on a BG/Q architecture with XL compilers. I would like to report some issues and ask for your help.

1. The first issue I ran into has been that xlc was not properly detected. It sufficed to change line 294 of m4/compiler.m4 in
is_ibm_xlc="`($CXX -v 2>&1) | egrep -i 'xlc'`"
(and boostrap) to fix this.

2. Exodus fails to build since it seems that XL Fortran compiler requires a different syntax when defining a preprocessor macro (-WF,-D instead of -D). A simple workaround is
cd contrib/exodusii/v5.22/exodus
make -k
sed -i 's/-D/-WF,-D/g' Makefile

3. libMesh library is built correctly but I cannot link executables.

The error that I get is:
/bgsys/drivers/ppcfloor/gnu-linux/powerpc64-bgq-linux/bin/ld: /bgsys/drivers/V1R2M0/ppc64/comm/sys-fast/lib/libpami.a(component-pami--CAPI.cnk.o)(.text._ZNSt8_Rb_treeIjSt4pairIKjjESt10_Select1stIS2_ESt4lessIjESaIS2_EE8_M_eraseEPSt13_Rb_tree_nodeIS2_E[_ZNSt8_Rb_treeIjSt4pairIKjjESt10_Select1stIS2_ESt4lessIjESaIS2_EE8_M_eraseEPSt13_Rb_tree_nodeIS2_E]+0xbc): sibling call optimization to `_ZNSt8_Rb_treeIjSt4pairIKjjESt10_Select1stIS2_ESt4lessIjESaIS2_EE8_M_eraseEPSt13_Rb_tree_nodeIS2_E' does not allow automatic multiple TOCs; recompile with -mminimal-toc or -fno-optimize-sibling-calls, or make `_ZNSt8_Rb_treeIjSt4pairIKjjESt10_Select1stIS2_ESt4lessIjESaIS2_EE8_M_eraseEPSt13_Rb_tree_nodeIS2_E' extern

I tried adding -mminimal-toc or -fno-optimize-sibling-calls or -qminimaltoc to CXXFLAGS without any luck.

My configure options are as follows:
export CXX="mpixlcxx_r"
export CC="mpixlc_r"
export FC="mpixlf90_r"
export F77="mpixlf77_r"
bash $SRC_DIR/configure --enable-mpi --with-mpi="$BGQ_XL_HOME" --with-cxx=$CXX --with-cc=$CC --with-fc=$FC --with-f77=$F77 --disable-shared --enable-all-static --with-methods="dbg" --enable-petsc --enable-metis --with-metis=PETSc --prefix="$INSTALL_DIR"

Everything works fine removing "--enable-petsc" from the configuration options, so the problem appears to be caused by PETSc.
I think however that the PETSc installation is ok, since PETSc examples and tutorials compile (and link) fine.

Do you have any suggestion?
Thank you,
best regards,
Francesco Ballarin