For those following along, I ended up doing four levels of bisects to find the actual problem. First the bisect I described above to identify the problematic fi

For those following along, I ended up doing four levels of bisects to find the actual problem. First the bisect I described above to identify the problematic file–stackMapTable.cpp. Then another on the functions inside of the file with optimizations and without to find the function that was broken: StackMapReader::next(StackMapFrame, bool, unsigned short, unsigned short, JavaThread). With that I manually inspected the code generated, found that it was wrong, and then did a bisect on optimization passes to see which one broke it (ConstraintEliminationPass). Finally one last bisect to see the history of where this came from (seems to be fixed in a change Xcode hasn't pulled yet).