https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90186
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |INVALID
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Note that using #pragma pack(1) on struct Ipv4 makes u_short members not
naturally aligned and thus code like
void UpdateChecksum()
{
u_long sum(0);
SetChecksum(0);
u_short *buf = (u_short*)ip->Payload();
u_long nwords = ip->PayloadSize() / 2;
for (unsigned i = 0; i < nwords; ++i)
{
sum += ntohs(*buf++);
dereferences pointers to u_short that might not be aligned to a 2 byte
boundary.
Confirmed though, even when using -fno-inline. -fno-strict-aliasing fixes
it. Possibly the very same issue above - using u_short * to access memory
with a different dynamic type. The same happens here:
buf = (u_short*)&ph;
nwords = 6;
for (unsigned i = 0; i < nwords; ++i)
{
sum += ntohs(*buf++);
ph is of type PseudoHeader. You cannot use lvalues of type u_short to
refer to them.
