http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59734
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2014-01-09
CC| |jason at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm, the C++ memory model only disallows this because the padding might be
re-used in a derived class like
struct foo : str {
short x;
};
but at least 'str' has to be non-POD for this to happen it seems. That is, for
struct str {
str() {}
volatile unsigned f1: 8;
};
struct foo : str { short x; };
sizeof (foo) == sizeof (str) == 4 and thus accessing f1 with SImode would
introduce a data race with 'x' which is not allowed.
If the FE would provide a way to tell whether tail padding might be possibly
re-used we can avoid this for the simple case. Jason?
That is, add langhook that tells us this (or a flag on the types).
