0|$ git grep -E -o "__builtin[a-z_]+" -- xen | cut -d':' -f2 | sort -u
__builtin_bswap
__builtin_clz
__builtin_clzll
__builtin_constant_p
__builtin_ctz
__builtin_ctzll
__builtin_expect
__builtin_frame_address
__builtin_has_attribute
__builtin_memchr
__builtin_memcmp
__builtin_memcpy
__builtin_memmove
__builtin_memset
__builtin_offsetof
__builtin_popcount
__builtin_popcountll
__builtin_prefetch
__builtin_return_address
__builtin_strcasecmp
__builtin_strchr
__builtin_strcmp
__builtin_strlen
__builtin_strncasecmp
__builtin_strncmp
__builtin_strrchr
__builtin_strstr
__builtin_trap
__builtin_types_compatible_p
__builtin_unreachable
__builtin_va_arg
__builtin_va_copy
__builtin_va_end
__builtin_va_list
__builtin_va_start