https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61927
Bug ID: 61927
Summary: Optimization bug (regression): Array comparison yields
unassigned result at -O3
Product: gcc
Version: 4.9.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: krefson at gmail dot com
The attached code, which tests an allocatable array for nonzero values, works
correctly when compiled at -O1 and -O3, but malfunctions at -O3.
$ gfortran -O2 arrayop2.f90
$ ./a.out
Symm_Nonzero
T F F F T F F F T 3
T F F F T F F F T 3
T F F F F T F T F 3
T F F F F T F T F 3
T F F F T F F F T 3
T F F F T F F F T 3
T F F F F T F T F 3
T F F F F T F T F 3
$ ./a.out
Symm_Nonzero
T F F F T F F F T 3
F F F T T F F T T 4
T T T F T T F F T****
T F F T F T T F F****
F F T T F F T T T 5
T T T T T F F T T****
T T T T F F T T T****
T T F T T T T T T****
Running under valgrind reveals that some elements of the result array
"symm_nonzero" contain uninitialized data in the -O3 case.
This is a regression in 4.9.1. The code works correctly at -O3 under 4.8,2
uname -a
Linux gibbs 3.12.21-desktop-2.mga4 #1 SMP Thu Jun 5 21:33:44 UTC 2014 x86_64
x86_64 x86_64 GNU/Linux
$ gfortran --version
GNU Fortran (GCC) 4.9.1 20140709 (prerelease)
Copyright (C) 2014 Free Software Foundation, Inc.
