https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108187
--- Comment #2 from Ilya Maximets <i.maximets at ovn dot org> --- (In reply to Richard Biener from comment #1) > Well, between the store to ->source and the read from it is the call > to dp_packet_use_afxdp which gets &xpacket->packet as argument and thus > needs to be treated as clobbering ->source. So GCC can indeed not know > that ->source is DPBUF_AFXDP since the path is not provable impossible. > dp_packet_use_afxdp doesn't even get a const struct dp_packet * argument > (not that this would semantically change things in C). Hmm, dp_packet_use_afxdp() is the function that sets source to DPBUF_AFXDP and initializes other parts of the structure. So, it cannot take a const argument. If GCC just doesn't look inside the dp_packet_use_afxdp() function at all here, then it will indeed not know that the source is DPBUF_AFXDP now. However, I'm not sure why the issue doesn't appear with -O0 then.
