make check crashes on POWER8 machine

Hi,

I've encountered a problem with Postgres on PowerPC machine. Sometimes
make check on REL_12_STABLE branch crashes with segmentation fault.

It seems that problem is in errors.sql when executed 

select infinite_recures(); statement

so stack trace, produced by gdb is too long to post here.

Problem is rare and doesn't occur on all runs of make check.
When I run make check repeatedly it occurs once a several hundreds runs.

It seems that problem is architecture-dependent, because I cannot
reproduce it on x86_64 CPU with more than thousand runs of make check.

Machine is KVM virtual server on POWER8 system with following CPU:

$ lscpu
Architecture:          ppc64le
Byte Order:            Little Endian
CPU(s):                32
On-line CPU(s) list:   0-31
Thread(s) per core:    8
Core(s) per socket:    4
Socket(s):             1
NUMA node(s):          1
Model:                 2.0 (pvr 004d 0200)
Model name:            POWER8 (architected), altivec supported
Hypervisor vendor:     KVM
Virtualization type:   para
L1d cache:             64K
L1i cache:             32K
NUMA node0 CPU(s):     0-31

Running RedHat 7.6.



I've collected  all relevant information i've can think of (including
210Mb core file, git commit id, configure and backend logs, list of
installed RPMs) and put it into Google Drive
https://drive.google.com/file/d/1Xs7DixBhMPEmViGUt5wAMewB6_xbZirY/view

Hope that somebody more experienced with POWER CPUs can suggest
something about this problem.

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