Build failure with clang on older CPU :Illegal instruction

[Luke Benes]

Noel,

After https://cgit.freedesktop.org/libreoffice/core/commit/?id=09f77e8ed51fc64fccc6a14e87eed48b2f15a28d
    loplugin:unusedmethods

Clang 7 on KDE Neon x86-64, and clang 10-git on openSUSE Tumbleweed i686 is failing with 

[CUT] tools_test
Illegal instruction (core dumped)

It looks like /core/workdir/LinkTarget/Executable/cppunittester generated /core/workdir/CppunitTest/tools_test.test.core/core
Backtraces:
[New LWP 8225]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `/core/workdir/Link'.
Program terminated with signal SIGILL, Illegal instruction.
#0  0x00007f90e824f538 in CppUnit::TestSuiteFactory<(anonymous namespace)::CpuInstructionSetSupport>::makeTest() () from /core/workdir/LinkTarget/CppunitTest/libtest_tools_test.so
warning: File "/core/instdir/program/libuno_sal.so.3-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
To enable execution of this file add
        add-auto-load-safe-path /core/instdir/program/libuno_sal.so.3-gdb.py
line to your configuration file "/home/luke/.gdbinit".
To completely disable this security protection add
        set auto-load safe-path /
line to your configuration file "/home/luke/.gdbinit".
For more information about this security protection see the
"Auto-loading safe path" section in the GDB manual.  E.g., run from the shell:
        info "(gdb)Auto-loading safe path"
warning: File "/core/instdir/program/libbasegfxlo.so-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
warning: File "/core/instdir/program/libtllo.so-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
warning: File "/core/instdir/program/libuno_cppu.so.3-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
warning: File "/core/instdir/program/libvcllo.so-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
warning: File "/core/instdir/program/libsvllo.so-gdb.py" auto-loading has been declined by your `auto-load safe-path' set to "$debugdir:$datadir/auto-load".
rax            0x7f90e9fa06f8   140260377495288
rbx            0x8e8c90 9342096
rcx            0x7ffdd580c570   140728185439600
rdx            0x7f90e8463a48   140260348934728
rsi            0x952a10 9775632
rdi            0x7ffdd580c570   140728185439600
rbp            0x7ffdd580c6a0   0x7ffdd580c6a0
rsp            0x7ffdd580c550   0x7ffdd580c550
r8             0x952da0 9776544
r9             0x952dd0 9776592
r10            0x0      0
r11            0x0      0
r12            0x7ffdd580cc10   140728185441296
r13            0x7      7
r14            0x952a10 9775632
r15            0x7ffdd580c978   140728185440632
rip            0x7f90e824f538   0x7f90e824f538 <CppUnit::TestSuiteFactory<(anonymous namespace)::CpuInstructionSetSupport>::makeTest()+168>
eflags         0x10202  [ IF RF ]
cs             0x33     51
ss             0x2b     43
ds             0x0      0
es             0x0      0
fs             0x0      0
gs             0x0      0

Thread 1 (Thread 0x7f90ea199740 (LWP 8225)):
#0  0x00007f90e824f538 in CppUnit::TestSuiteFactory<(anonymous namespace)::CpuInstructionSetSupport>::makeTest() () at /core/workdir/LinkTarget/CppunitTest/libtest_tools_test.so
#1  0x00007f90e9d66f3b in CppUnit::TestFactoryRegistry::addTestToSuite(CppUnit::TestSuite*) () at /core/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.14.so.0
#2  0x00007f90e9d66e67 in CppUnit::TestFactoryRegistry::makeTest() () at /core/workdir/UnpackedTarball/cppunit/src/cppunit/.libs/libcppunit-1.14.so.0
#3  0x00000000004042a9 in (anonymous namespace)::ProtectedFixtureFunctor::run() const ()
#4  0x00000000004035be in main ()


Error: a unit test failed, please do one of:

make CppunitTest_tools_test CPPUNITTRACE="gdb --args"
...
$ cat /proc/cpuinfo 
model name      : Intel(R) Core(TM) i7 CPU         920  @ 2.67GHz

Newer CPU's like my Broadwell Core i3 Processors have no issue with the same distros. 

What additional debugging info would you like? 

-Luke