10913 glxgears PSIG  SIGILL SIG_DFL code=ILL_BTCFI addr=0x21ca5a3000 trapno=905969666

Anyone have suggestions as to how to track this down any further?
Nothing really useful from gdb (this is from an X build with -g). I
tried LD_DEBUG to see if that would help ID the library but it didn't
help me. ltrace with some kernel trace flags enabled too showed it
happening after opening mesa_shader_cache and doing some zlib
operations. The only arm64 asm I noticed in X was in pixman.

$ egdb glxgears
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Reading symbols from glxgears...
(gdb) r
Starting program: /usr/X11R6/bin/glxgears
[New thread 270983]
[New thread 518046]
[New thread 508613]
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[New thread 504069]
[New thread 354905]
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[New thread 482769]
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[New thread 111193]
[New thread 617204]
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[New thread 578587]

Thread 1 received signal SIGILL, Illegal instruction.
0x000000153dac9000 in ?? ()
(gdb) bt
#0  0x000000153dac9000 in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
(gdb) disassemble
No function contains program counter for selected frame.
(gdb) q
A debugging session is active.

	Inferior 1 [process 68970] will be killed.

Quit anyway? (y or n) y