To be more specific. These two member variables are at offset 0x8: unsigned ID : 8; unsigned SubclassData : 24;
When setSubclassData() isn't inlined, it's called with the address of 'SubclassData' in %rdi...: 0x00007ffff76d684f <+71>: lea 0x9(%rdi),%r12 0x00007ffff76d6853 <+75>: or $0x1,%esi 0x00007ffff76d6856 <+78>: mov %r12,%rdi 0x00007ffff76d6859 <+81>: callq 0x7ffff76d6774 <llvm::Type::setSubclassData(unsigned int)> ...but then, it writes more than 24 bits to that address, writing zeroes into the next member: 0x00007ffff76d6774 <+0>: mov %esi,%eax 0x00007ffff76d6776 <+2>: sub $0x8,%rsp 0x00007ffff76d677a <+6>: and $0xffffff,%eax 0x00007ffff76d677f <+11>: cmp %esi,%eax 0x00007ffff76d6781 <+13>: mov %eax,(%rdi) # corruption -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/910363 Title: miscompile writing to bitfield at -Os To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gcc-4.5/+bug/910363/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
