The hack in may_propagate_copy:
/* FIXME. GIMPLE is allowing pointer assignments and comparisons of
pointers that have different alias sets. This means that these
pointers will have different memory tags associated to them.
If we allow copy propagation in these cases, statements de-referencing
the new pointer will now have a reference to a different memory tag
with potentially incorrect SSA information.
This was showing up in libjava/java/util/zip/ZipFile.java with code
like:
struct java.io.BufferedInputStream *T.660;
struct java.io.BufferedInputStream *T.647;
struct java.io.InputStream *is;
struct java.io.InputStream *is.662;
[ ... ]
T.660 = T.647;
is = T.660; <-- This ought to be type-casted
is.662 = is;
Also, f/name.c exposed a similar problem with a COND_EXPR predicate
that was causing DOM to generate and equivalence with two pointers of
alias-incompatible types:
struct _ffename_space *n;
struct _ffename *ns;
[ ... ]
if (n == ns)
goto lab;
...
lab:
return n;
I think that GIMPLE should emit the appropriate type-casts. For the
time being, blocking copy-propagation in these cases is the safe thing
to do. */
Should be able to removed now as both the DOM and java front-ends issues have
been fixed now.
PR 22368 referenced the bugs which were filed so this hack could be removed.
Even though PR 22368
references more than what is needed to remove this hack, I am going to mark
this new bug as
depending on that bug.
--
Summary: hack in may_propagate_copy should be able to removed
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: minor
Priority: P2
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: pinskia at gcc dot gnu dot org
CC: dnovillo at gcc dot gnu dot org,gcc-bugs at gcc dot gnu
dot org
BugsThisDependsOn: 22368
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23329
