On Mon, Nov 18, 2013 at 8:12 PM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
2013/11/18 Jeff Law <law@redhat.com>:
On 11/18/13 11:27, Ilya Enkovich wrote:
How does pointer passed to regular function differ from pointer passed
to splitted function? How do I know then which pointer is to be passed
with bounds and wchich one is not? Moreover current ABI does not allow
to pass bounds with no pointer or pass bounds for some pointers in the
call only.
But I don't see any case in function splitting where we're going to want to
pass the pointer without the bounds. If you want the former, you're going
to want the latter.
There are at least cases when checks are eliminated or when lots of
pointer usages are accompanied with few checks performed earlier (e.g.
we are working with array). In such cases splitted part may easily get
no bounds.
I really don't see why you need to do anything special here. At the most an
assert in the splitting code to ensure that you don't have a situation where
there's mixed pointers with bounds and pointers without bounds should be all
you need or that you passed a bounds with no associated pointer :-)
It would also require generation of proper bind_bounds calls in the
original function and arg_bounds calls in a separated part. So,
special support is required.
Well, only to keep proper instrumentation. I hope code still works
(doesn't trap) when optimizations "wreck" the bounds? Thus all
these patches are improving bounds propagation but are not required
for correctness? If so please postpone all of them until after the
initial support is merged. If not, please make sure BND instrumentation
works conservatively when optimizations wreck it.