Re: buildfarm animal shoveler failing with "Illegal instruction"

Mark Wong <mark(at)2ndquadrant(dot)com> writes:
> I'm getting Tom set up with access too, in case he has time before me to
> get a stack trace to see what's happening...

tl;dr: it's hard to conclude that this is anything but a compiler bug.

I was able to reproduce this on shoveler's host, but only when using
the compiler shoveler uses (clang-3.9), not the 6.3 gcc that's also
on there and is of similar vintage. Observations:

* You don't need any complicated test case; "pg_dump template1"
is enough.

* Reverting 1ed6b8956's addition of a "postfix operators are not supported
anymore" warning to dumpOpr() makes it go away. This despite the fact
that that code is never reached when dumping template1. (We do enter
dumpOpr, but the oprinfo->dobj.dump test always fails.)

* Reducing the optimization level to -O1 or -O0 makes it go away.

* Inserting a debugging fprintf in dumpOpr makes it go away.

Since clang 3.9 is several years old, maybe we could move shoveler
up to a newer version? Or dial it down to -O1 optimization?

regards, tom lane