------- Comment #1 from abel at gcc dot gnu dot org 2009-08-12 07:40 -------
Confirmed on trunk. As we discussed on IRC, the below obvious patch makes
nonoverlapping_component_refs_p punt when !flag_strict_aliasing and thus fixes
the testcase. I have looked at the other rtl alias oracle functions used in
*_dependence, and it seems that they are safe. E.g.,
fixed_scalar_and_varying_struct_p already punts when fno-strict-aliasing, and
the other stuff mainly deals with base+offset disambiguations.
(Interestingly enough, I couldn't make a test case in which incorrect PRE or
CSE (not DSE) would happen, as these probably don't look through stores. On
some platforms though, the scheduler will likely fail.)
I will post the patch after bootstrap+regtest.
Index: alias.c
===================================================================
*** alias.c (revision 150675)
--- alias.c (working copy)
*************** nonoverlapping_component_refs_p (const_t
*** 1980,1985 ****
--- 1980,1988 ----
{
const_tree fieldx, fieldy, typex, typey, orig_y;
+ if (!flag_strict_aliasing)
+ return false;
+
do
{
/* The comparison has to be done at a common type, since we don't
--
abel at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |abel at gcc dot gnu dot org
AssignedTo|unassigned at gcc dot gnu |abel at gcc dot gnu dot org
|dot org |
Status|UNCONFIRMED |ASSIGNED
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2009-08-12 07:40:55
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41033
