------- Comment #4 from rguenth at gcc dot gnu dot org 2010-01-05 11:31 -------
Somehow patched openSUSE GCC 4.3 is also affected.
<bb 2>:
# index_18 = VDEF <index_17(D)>
index = 0;
# index_21 = VDEF <index_18>
# SMT.57_22 = VDEF <SMT.57_19(D)>
# SMT.58_23 = VDEF <SMT.58_20(D)>
table_p_1 = init ();
D.1295_3 = &table_p_1->data[1];
# SMT.57_24 = VDEF <SMT.57_22>
table_p_1->data[1].num = 0;
goto <bb 4>;
<bb 3>:
# VUSE <SMT.58_10>
D.1355_5 = D.1295_3->num;
D.1356_6 = D.1355_5 + 1;
# SMT.58_25 = VDEF <SMT.58_10>
D.1295_3->num = D.1356_6;
index_8 = index_7 + 1;
<bb 4>:
# index_7 = PHI <0(2), index_8(3)>
# SMT.58_10 = PHI <SMT.58_23(2), SMT.58_25(3)>
if (index_7 == 0)
goto <bb 3>;
else
goto <bb 5>;
<bb 5>:
# VUSE <SMT.57_24>
D.1355_9 = table_p_1->data[1].num;
FRE CSEs the load from table_p_1->data[1].num with the store in BB2 not
seeing the must-alias in BB3. And it's obvious why when you look at the
vops.
SMT.58 needs to have SMT.57 in its may-aliases but doesn't have it
for some reason.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Keywords| |alias, wrong-code
Known to fail| |4.4.0 4.4.2
Known to work| |4.2.4 4.3.4 4.5.0
Last reconfirmed|0000-00-00 00:00:00 |2010-01-05 11:31:37
date| |
Summary|FRE optimizes away valid |[4.4 Regression] FRE
|code after IPA inlining |optimizes away valid code
| |after IPA inlining
Target Milestone|--- |4.4.3
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42614
