https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100152
--- Comment #16 from lucier at math dot purdue.edu --- I have figured out how to build and then run the app in lldb to reliably reproduce the error. To configure and build Gambit, the Scheme->C compiler: 51 8:56 mkdir gambit-test 52 8:56 cd gambit-test 53 8:56 git clone https://github.com/gambit/gambit.git 54 8:57 cd gambit 55 9:00 ./configure 'CC=/usr/local/gcc-10.3.0/bin/gcc -save-temps -g' '--enable-single-host' '--enable-shared' 56 9:01 make -j12 After a few minutes the "make -j12" should end with the message: *** to compile the builtin modules you should: make modules Then in the same directory I ran a command to just print the version number and configuration information of Gambit; I ran the interpreter gsi instead of the compiler gsc: [Bradleys-Mac-mini:~/programs/gambit-test/gambit] lucier% lldb gsi/gsi (lldb) target create "gsi/gsi" Current executable set to '/Users/lucier/programs/gambit-test/gambit/gsi/gsi' (x86_64). (lldb) process launch -v DYLD_LIBRARY_PATH=./lib:./gsi:./gsc -- -:~~bin=./bin,~~lib=./lib,~~include=./include -v Process 39231 launched: '/Users/lucier/programs/gambit-test/gambit/gsi/gsi' (x86_64) Process 39231 stopped * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_INSTRUCTION (code=12, subcode=0x0) frame #0: 0x000000010012d010 libgambit.dylib`___SCMOBJ_to_NONNULLSTRING(obj=<unavailable>, x=0x00007ffeefbfa6b8, arg_num=<unavailable>, char_encoding=<unavailable>, fudge=<unavailable>) at c_intf.c:3280:173 3277 p = r; 3278 3279 for (i=0; i<n; i++) -> 3280 ___UTF_8_put (&p, ___INT(___STRINGREF(obj,___FIX(i)))); 3281 3282 *p = 0; 3283 Target 0: (gsi) stopped. This is my first time running lldb, so I'm a bit slow. To your other questions: It's not JIT-generated code, and I'll work on building a mainline compiler to test it, too. Hope this helps.