On 12/13/2016 04:41 PM, Jeff Law wrote:
On 12/13/2016 12:13 AM, Florian Weimer wrote:
Is it possible to use the stack from inline assembly? I'm particularly
interested in i386 and x86_64, and push/pop instructions and function
calls.
You can push/pop and perform a function call. Obviously you have to
express what's going on from a dataflow standpoint if you use a new
style asm -- that includes notifying GCC of the registers clobbered at
the call point and the memory usage.
How do I express that? It's not that %rsp is clobbered, its unchanged.
How can I express a clobber on memory which does not even have an
address as far as C is concerned?
I do not think the use of inline assembler disables the red zone on the
x86.
I think Andrew's example shows that we do have a problem here. I
wouldn't have thought it so easy to demonstrate.
I'm not aware of a constraint that expresses this properly.
Thanks,
Florian
