------- Comment #17 from rguenth at gcc dot gnu dot org 2007-05-01 14:00
-------
Without -fstrict-aliasing we mark this_20->functor_ = D.2946; obviously
necessary
because it is is_hidden_global_store ():
;; Function sigc::slot0 A::bar() (_ZN1A3barEv)
-Marking useful stmt: this_20->functor_ = D.2946;
-
-Marking useful stmt: D.3047_33 = operator new (20);
+Marking useful stmt: D.3054_33 = operator new (20);
Marking useful stmt: this_35->functor_ = D.2514;
-Marking useful stmt: D.3053_46->call_ = call_it;
+Marking useful stmt: D.3060_46->call_ = call_it;
Marking useful stmt: return <retval>;
without that we DCE too much as
# SFT.80_6 = V_MUST_DEF <SFT.80_5>;
D.2378.func_ptr_ = foo;
...
# D.2951_27 = V_MUST_DEF <D.2951_26>;
# VUSE <SFT.80_6>;
D.2951 = D.2378;
# SFT.77_50 = V_MAY_DEF <SFT.77_49>;
# VUSE <D.2951_27>;
this_20->functor_ = D.2951;
# SFT.77_63 = V_MUST_DEF <SFT.77_50>;
D.2514.bound1_.visited_ = D.2953_31;
the last store kills the assignment to this_20->functor_. Note that while
we have uses for D.2951_27 and SFT.80_6 the structure assignment to
this_20->functor_ for some reason shares the SFT with the assignment
to D.2514.bound1_.visited_. So this may be as well a frontend bug.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |NEW
Ever Confirmed|0 |1
Keywords| |alias
Last reconfirmed|0000-00-00 00:00:00 |2007-05-01 14:00:47
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30252
