The optimization is under -O1 in gcc, and can be turned off with `-fno-merge-constants`. However, if you use lld as a linker, strings are duplicated by default

The optimization is under -O1 in gcc, and can be turned off with `-fno-merge-constants`. However, if you use lld as a linker, strings are duplicated by default. To merge them, you need `gcc -O1 -Wl,-O3 -fuse-ld=lld`. So, it is a combination of compiler and linker optimizations.