"D. Hugh Redelmeier" <[EMAIL PROTECTED]> writes:
| | From: Gabriel Dos Reis <[EMAIL PROTECTED]>
|
| | After many exchanges via private mails and
| | looking at the various reports related to this issue, it has become
| | clear to me that the interpretations offered to justify why GCC is
| | behaving the way it does seem to go beyond what can be inferred.
|
| OK.
|
| Is there a consensus on this?
JSM, please chime in.
| If not, how can a consensus be reached?
try to explain those who read the standard to you their interpretation
does not match the intent and the letter? Sorry :-)
More seriously, at this point Daniel Berlin has indicated that he gives
"less of a crap about volatile and optimizing volatile than [he does]
const, restrict, etc". So that is, I hope, a path to a saner behaviour
from the code transformation part of the compiler.
| If so, how can we get a fix?
|
| I think that is urgent. This bug is causing X to misbehave and the
| current workarounds might be harmful. Who knows what other
| manifestations might be lurking?
|
| As I said, I'm not a GCC hacker. Who is the likely maintainer to fix
| this? Does he or she agree that this needs to be done? Urgently?
Joseph S. Myers (jsm at polyomino.org.uk) and Richard Henderson (rth
at redhat.com) are the C front-end maintainers. The following is
from the last message I received from Joseph (on access through volatile
lvalue expression):
# Using always the qualification of the lvalue is reasonable semantics to
# specify (I don't know about to implement). It's still a matter of making
# a choice and documenting and implementing it.
The issue is compounded by the fact that the code transformation part
(the "optimizer") is maintained by a different set of people and it takes
coordination between both worlds to arrive to a useful semantics.
At this point we need:
(1) agreement from C and C++ maintainers on access through volatile
lvalue
(2) agreement with the middle-end maintainers not to "optimize"
volatile lvalue expressions
(3) document the behaviour.
The most important for you and X is to have (2) done, i.e. Richard
Henderson, Roger Sayle, Daniel Berlin and others.
-- Gaby
