(In reply to Reinhard Max from comment #39) > I've seen this happen on all three versions of PostgreSQL that support LLVM > (11, 12 and 13), but only on s390x and only in about 4 out of 5 build runs > (within the short period over which I monitored it). Since it comes from ld (or collect2?) and that's an LTO link, I suppose it might be a race condition. I agree, it should be a separate bug. Maybe add Michael Matz for binutils and Martin Liska for GCC LTO. IBM tends to have weaker memory models, and that race might just not materialize with the stronger model of x86.