Kernel Build error with gcc 9

[damian]

Hello all,

i know GCC 9 is currently in deployment progress. But i tried to build a
kernel 4.19RC8 with gcc 9 and i got the following error message:

Kernel: arch/x86/boot/bzImage is ready  (#1)
ERROR: "__popcountdi2" [drivers/net/wireless/broadcom/brcm80211/brcmfmac/brcmfmac.ko] undefined!
ERROR: "__popcountdi2" [drivers/net/ethernet/broadcom/bnx2x/bnx2x.ko] undefined!
/home/damian/kernel/linux/scripts/Makefile.modpost:92: die Regel fÃr Ziel â__modpostâ scheiterte
make[2]: *** [__modpost] Fehler 1

with gcc 8 it works fine.
 
Any suggestion what could be the cause ?

Best regards
Damian