mipsel out-of-memory building dolfinx 0.4.0

Hi MIPS porters, I need helping with the build of fenics-dolfinx on 
mipsel from experimental, 
https://salsa.debian.org/science-team/fenics/fenics-dolfinx/-/tree/experimental

It previously built fine, but the latest version 1:0.4.1 has evidently 
grown large enough to break on mipsel.

mip64el builds successfully, as we might expect. But it's not simply a 
32-bit issue in the sense that i386, armel, armhf are all still building 
successfully.

Build logs can be found at 
https://buildd.debian.org/status/logs.php?pkg=fenics-dolfinx&arch=mipsel

In the build for 1:0.4.1-1exp1 we see:

[ 83%] Building CXX object CMakeFiles/cpp.dir/dolfinx/wrappers/nls.cpp.o
/usr/bin/c++ -DBOOST_ALL_NO_LIB -DBOOST_CHRONO_DYN_LINK 
-DBOOST_TIMER_DYN_LINK -DDOLFINX_VERSION=\"0.4.1\" -DHAS_PTSCOTCH 
-DHAS_SLEPC -D_FILE_OFFSET_BITS=64 -Dcpp_EXPORTS 
-I/usr/lib/petscdir/petsc3.16/mipsel-linux-gnu-complex/lib/python3/dist-packages/petsc4py/include 
-I/usr/lib/python3/dist-packages/mpi4py/include -isystem 
/usr/include/python3.9 -isystem 
/usr/lib/python3/dist-packages/pybind11/include -isystem 
/usr/lib/python3/dist-packages/ffcx/codegeneration -isystem 
/usr/lib/mipsel-linux-gnu/openmpi/include -isystem 
/usr/lib/mipsel-linux-gnu/openmpi/include/openmpi -isystem 
/usr/lib/petscdir/petsc3.16/mipsel-linux-gnu-complex/include -isystem 
/usr/include/hdf5/openmpi -isystem 
/usr/lib/slepcdir/slepc3.16/mipsel-linux-gnu-complex/include -g -O2 
-ffile-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat 
-Werror=format-security -isystem 
/<<PKGBUILDDIR>>/debian/tmp-complex/usr/include -DVERSION_INFO=\"0.4.1\" 
-O3 -DNDEBUG -fPIC -fvisibility=hidden -Wall -Werror -pedantic -flto 
-fno-fat-lto-objects -pthread -Wdate-time -D_FORTIFY_SOURCE=2 -std=c++17 
-MD -MT CMakeFiles/cpp.dir/dolfinx/wrappers/nls.cpp.o -MF 
CMakeFiles/cpp.dir/dolfinx/wrappers/nls.cpp.o.d -o 
CMakeFiles/cpp.dir/dolfinx/wrappers/nls.cpp.o -c 
/<<PKGBUILDDIR>>/python/dolfinx/wrappers/nls.cpp
[ 91%] Building CXX object 
CMakeFiles/cpp.dir/dolfinx/wrappers/refinement.cpp.o
/usr/bin/c++ -DBOOST_ALL_NO_LIB -DBOOST_CHRONO_DYN_LINK 
-DBOOST_TIMER_DYN_LINK -DDOLFINX_VERSION=\"0.4.1\" -DHAS_PTSCOTCH 
-DHAS_SLEPC -D_FILE_OFFSET_BITS=64 -Dcpp_EXPORTS 
-I/usr/lib/petscdir/petsc3.16/mipsel-linux-gnu-complex/lib/python3/dist-packages/petsc4py/include 
-I/usr/lib/python3/dist-packages/mpi4py/include -isystem 
/usr/include/python3.9 -isystem 
/usr/lib/python3/dist-packages/pybind11/include -isystem 
/usr/lib/python3/dist-packages/ffcx/codegeneration -isystem 
/usr/lib/mipsel-linux-gnu/openmpi/include -isystem 
/usr/lib/mipsel-linux-gnu/openmpi/include/openmpi -isystem 
/usr/lib/petscdir/petsc3.16/mipsel-linux-gnu-complex/include -isystem 
/usr/include/hdf5/openmpi -isystem 
/usr/lib/slepcdir/slepc3.16/mipsel-linux-gnu-complex/include -g -O2 
-ffile-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong -Wformat 
-Werror=format-security -isystem 
/<<PKGBUILDDIR>>/debian/tmp-complex/usr/include -DVERSION_INFO=\"0.4.1\" 
-O3 -DNDEBUG -fPIC -fvisibility=hidden -Wall -Werror -pedantic -flto 
-fno-fat-lto-objects -pthread -Wdate-time -D_FORTIFY_SOURCE=2 -std=c++17 
-MD -MT CMakeFiles/cpp.dir/dolfinx/wrappers/refinement.cpp.o -MF 
CMakeFiles/cpp.dir/dolfinx/wrappers/refinement.cpp.o.d -o 
CMakeFiles/cpp.dir/dolfinx/wrappers/refinement.cpp.o -c 
/<<PKGBUILDDIR>>/python/dolfinx/wrappers/refinement.cpp

cc1plus: out of memory allocating 17707045 bytes after a total of 
42041344 bytes


In the first instance I tried switching off LTO, adding the cmake 
configuration "set(CMAKE_INTERPROCEDURAL_OPTIMIZATION FALSE)" which 
deactivates -flto.
But it didn't fix the problem.  The corresponding log for 1:0.4.1-1exp2 
shows much the same problem,

   virtual memory exhausted: Cannot allocate memory

I then tried building on the porterbox eller.debian.org, reducing 
optimization from -O3  to -O2, but that gave the same result.

Finally I tried with no optimizations at all (-O0) via cmake option 
add_compile_options(-O0).  This did allow the object files to build, but 
then linking failed with relocation truncated:

[100%] Linking CXX shared module 
../lib.linux-mips-3.10/dolfinx/cpp.cpython-310-mipsel-linux-gnu.so
/usr/bin/cmake -E cmake_link_script CMakeFiles/cpp.dir/link.txt 
--verbose=1
/usr/bin/c++ -fPIC -g -O2 
-ffile-prefix-map=/home/dparsons/dolfinx/fenics-dolfinx=. 
-fstack-protector-strong -Wformat -Werror=format-security -isystem 
/home/dparsons/dolfinx/fenics-dolfinx/debian/tmp-complex/usr
/include -DVERSION_INFO=\"0.4.1\" -O3 -DNDEBUG -pthread -Wl,-z,relro 
-shared  -o 
../lib.linux-mips-3.10/dolfinx/cpp.cpython-310-mipsel-linux-gnu.so 
CMakeFiles/cpp.dir/dolfinx/wrappers/dolfinx.cpp.o CMakeFiles/cp
p.dir/dolfinx/wrappers/common.cpp.o 
CMakeFiles/cpp.dir/dolfinx/wrappers/fem.cpp.o 
CMakeFiles/cpp.dir/dolfinx/wrappers/geometry.cpp.o 
CMakeFiles/cpp.dir/dolfinx/wrappers/graph.cpp.o 
CMakeFiles/cpp.dir/dolfinx/wra
ppers/io.cpp.o CMakeFiles/cpp.dir/dolfinx/wrappers/la.cpp.o 
CMakeFiles/cpp.dir/dolfinx/wrappers/log.cpp.o 
CMakeFiles/cpp.dir/dolfinx/wrappers/mesh.cpp.o 
CMakeFiles/cpp.dir/dolfinx/wrappers/nls.cpp.o CMakeFiles/c
pp.dir/dolfinx/wrappers/refinement.cpp.o  
-Wl,-rpath,/home/dparsons/dolfinx/fenics-dolfinx/debian/tmp-complex/usr/lib/mipsel-linux-gnu:/usr/lib/mipsel-linux-gnu/openmpi/lib:/usr/lib/mipsel-linux-gnu/hdf5/openmpi
:/usr/lib/slepcdir/slepc3.16/mipsel-linux-gnu-complex/lib:/usr/lib/petscdir/petsc3.16/mipsel-linux-gnu-complex/lib 
/home/dparsons/dolfinx/fenics-dolfinx/debian/tmp-complex/usr/lib/mipsel-linux-gnu/libdolfinx_com
plex.so.0.4.1 /usr/lib/mipsel-linux-gnu/libbasix.so.0.4.2 
/usr/lib/mipsel-linux-gnu/libboost_timer.so.1.74.0 
/usr/lib/mipsel-linux-gnu/libboost_chrono.so.1.74.0 
/usr/lib/mipsel-linux-gnu/openmpi/lib/libmpi_cxx.so 
/usr/lib/mipsel-linux-gnu/openmpi/lib/libmpi.so 
/usr/lib/mipsel-linux-gnu/hdf5/openmpi/libhdf5.so 
/usr/lib/slepcdir/slepc3.16/mipsel-linux-gnu-complex/lib/libslepc_complex.so 
/usr/lib/petscdir/petsc3.16/mipsel-linux-gnu-complex/lib/libpetsc_complex.so
CMakeFiles/cpp.dir/dolfinx/wrappers/fem.cpp.o: in function 
`_PyObject_TypeCheck':
/usr/include/python3.10/object.h:247:(.text+0xa0): relocation truncated 
to fit: R_MIPS_CALL16 against `PyType_IsSubtype'
CMakeFiles/cpp.dir/dolfinx/wrappers/fem.cpp.o: in function `_Py_DECREF':
/usr/include/python3.10/object.h:500:(.text+0x174): relocation truncated 
to fit: R_MIPS_CALL16 against `_Py_Dealloc'
CMakeFiles/cpp.dir/dolfinx/wrappers/fem.cpp.o: in function 
`__Pyx_ImportFunction(_object*, char const*, void (**)(), char const*)':
/usr/lib/python3/dist-packages/mpi4py/include/mpi4py/mpi4py.MPI_api.h:111:(.text+0x46c): 
relocation truncated to fit: R_MIPS_CALL16 against 
`PyObject_GetAttrString'
/usr/lib/python3/dist-packages/mpi4py/include/mpi4py/mpi4py.MPI_api.h:114:(.text+0x498): 
relocation truncated to fit: R_MIPS_CALL16 against 
`PyDict_GetItemString'
/usr/lib/python3/dist-packages/mpi4py/include/mpi4py/mpi4py.MPI_api.h:116:(.text+0x4bc): 
relocation truncated to fit: R_MIPS_GOT16 against `PyExc_ImportError'
/usr/lib/python3/dist-packages/mpi4py/include/mpi4py/mpi4py.MPI_api.h:116:(.text+0x4c8): 
relocation truncated to fit: R_MIPS_CALL16 against `PyModule_GetName'
/usr/lib/python3/dist-packages/mpi4py/include/mpi4py/mpi4py.MPI_api.h:116:(.text+0x4f0): 
relocation truncated to fit: R_MIPS_CALL16 against `PyErr_Format'
/usr/lib/python3/dist-packages/mpi4py/include/mpi4py/mpi4py.MPI_api.h:122:(.text+0x514): 
relocation truncated to fit: R_MIPS_CALL16 against `PyCapsule_IsValid'
/usr/lib/python3/dist-packages/mpi4py/include/mpi4py/mpi4py.MPI_api.h:123:(.text+0x538): 
relocation truncated to fit: R_MIPS_GOT16 against `PyExc_TypeError'
/usr/lib/python3/dist-packages/mpi4py/include/mpi4py/mpi4py.MPI_api.h:123:(.text+0x544): 
relocation truncated to fit: R_MIPS_CALL16 against `PyModule_GetName'
/usr/lib/python3/dist-packages/mpi4py/include/mpi4py/mpi4py.MPI_api.h:123:(.text+0x560): 
additional relocation overflows omitted from the output
collect2: error: ld returned 1 exit status
gmake[4]: *** [CMakeFiles/cpp.dir/build.make:266: 
../lib.linux-mips-3.10/dolfinx/cpp.cpython-310-mipsel-linux-gnu.so] 
Error 1


At this point I'm out of clues.  What do you recommend?

Drew