[Bug c/57862] invalid read struct uint32_t member (ARMV5)

["mikpe at it dot uu.se" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57862

--- Comment #5 from Mikael Pettersson <mikpe at it dot uu.se> ---
Your test case contains this:

===snip===
struct iphdr
  {
...
  };
...
int main()
{
  char thePacket[1518];
  memset(thePacket, 0, 1518);

  thePacket[30] = 1;
  thePacket[31] = 2;
  thePacket[32] = 3;
  thePacket[33] = 4;

  struct ether_header* theEthHeader = (struct ether_header*)(thePacket);

  struct iphdr* theIpHeader = (struct iphdr*)((const unsigned
char*)(theEthHeader) + 14);

  struct in_addr myInAddr;
  myInAddr.s_addr = theIpHeader->daddr;
===snip===

The alignment of thePacket is arbitrary, so the alignment of theIpHeader is
unknown, and struct iphdr is not declared with attribute packed.  The final
load may therefore be misaligned.