------- Comment #5 from rguenth at gcc dot gnu dot org 2010-08-11 23:11 -------
(In reply to comment #4)
> I don't see that the const qualifier should be relevant: doesn't it simply
> indicate that the code is not permitted to write through that lvalue?
That's true which is why I think this bug is valid.
> (FWIW,
> the real code uses a memory mapped address and the const qualifier was placed
> on the address declaration by the chip manufacturer. I assume that a write to
> the location may be interpreted as a command to the hardware to
> self-destruct.)
>
> Given that, the existing behavior appears to be a clear violation of the
> requirement that volatile accesses not be re-ordered across sequence points.
>
> In concept, I like rguenth's solution (which I haven't tested), as it fits
> with
> the documented semantics of MEM_READONLY_P indicating "not modified during the
> lifetime of the program", something that certainly can't be said of any
> readable volatile object. That the RTL flag is stored in a field named
> "unchanging" is a lot more clear than "READONLY". I think that approach
> eliminates the need to muck with any of those other places where the same
> problem might be occurring.
Indeed.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
Last reconfirmed|2010-08-09 13:56:06 |2010-08-11 23:11:05
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45235
