I will attach a small reproducer.
/* Reproducer for optimizer bug in gcc svn trunk revision 114570
(as checked out 2006_06_12_0834 PDT)
To produce correct output:
g++ -Wall -O0 gcc_trunk_2006_06_12_0834_fc5_x86_64.cpp
./a.out
To see the bug:
g++ -Wall -O1 gcc_trunk_2006_06_12_0834_fc5_x86_64.cpp
./a.out
Note the difference in the last line of the output:
Correct: 1 0 0
Incorrect: 0 0 0
The output is also incorrect for -O2 and -O3.
The last line of the output is correct if compiled with:
g++ -Wall -O1 -DBAD_WORKAROUND gcc_trunk_2006_06_12_0834_fc5_x86_64.cpp
./a.out
Platform:
Fedora Core release 5 (Bordeaux)
Linux rosie.lbl.gov 2.6.15-1.2054_FC5 #1 SMP Tue Mar 14 15:48:20 EST 2006
x
86_64 x86_64 x86_64 GNU/Linux
% g++ -v
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: /net/rosie/scratch1/rwgk/gcc_trunk/configure
--prefix=/usr
/local_cci/gcc_trunk_2006_06_12_0834_fc5_x86_64 --enable-languages=c,c++
Thread model: posix
gcc version 4.2.0 20060612 (experimental)
*/
--
Summary: optimizer bug
Product: gcc
Version: 4.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: rwgk at yahoo dot com
GCC build triplet: x86_64-unknown-linux-gnu
GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28003
