Hardening must be performed at all levels of a system, including in the
compiler that is used to build that system. There are two viable compilers
in the free-software community now, each of which offers a different set of
security features. Kees Cook ran a session during the Toolchains
microconference at the 2019 Linux
Plumbers Conference that examined the security-feature support provided
by both GCC and LLVM Clang, noting the places where each one could stand to
improve.

Source: LWN.net – [$] Comparing GCC and Clang security features