This is not a bug in GCC.

You need to refresh your understanding of what `volatile' means.  In
particular, it doesn't mean that statements that both read and write a
memory position are executed with the bus locked.

Also not that x86 processors will *not* perform statements like,

	orl $0x80000000,_foo

with the bus locked between the read and the write.  For that, you need to
prefix the `orl' with a `lock' instruction.

Torbjorn