With -funsafe-loop-optimizations in flags, pr27285.c FAILs:
FAIL: gcc.c-torture/execute/pr27285.c execution, -O1
FAIL: gcc.c-torture/execute/pr27285.c execution, -O2
FAIL: gcc.c-torture/execute/pr27285.c execution, -O3 -fomit-frame-pointer
FAIL: gcc.c-torture/execute/pr27285.c execution, -O3 -fomit-frame-pointer
-funroll-loops
FAIL: gcc.c-torture/execute/pr27285.c execution, -O3 -fomit-frame-pointer
-funroll-all-loops -finline-functions
FAIL: gcc.c-torture/execute/pr27285.c execution, -O3 -g
FAIL: gcc.c-torture/execute/pr27285.c execution, -O2 -flto
FAIL: gcc.c-torture/execute/pr27285.c execution, -O2 -fwhopr
Output:
$ gcc -O -funsafe-loop-optimizations pr27285.i -Wunsafe-loop-optimizations
/mnt/svn/gcc-trunk/gcc/testsuite/gcc.c-torture/execute/pr27285.c: In function
'foo':
/mnt/svn/gcc-trunk/gcc/testsuite/gcc.c-torture/execute/pr27285.c:19:10:
warning: assuming that the loop counter does not overflow
[-Wunsafe-loop-optimizations]
/mnt/svn/gcc-trunk/gcc/testsuite/gcc.c-torture/execute/pr27285.c:17:9: warning:
assuming that the loop counter does not overflow [-Wunsafe-loop-optimizations]
$ ./a.out
Aborted
There is no overflow in the loop.
When compiled with -funsafe-loop-optimizations, the loop is exited when 'b' has
value 1 (that is, e[a] = d[a] & c; is not executed when b == 0). 'b' has values
of 25,17,19,1 (and then the loop ends) - without -funsafe-loop-optimizations,
it has values 25,17,19,1,0.
Even though -funsafe-loop-optimizations is expected to be unsafe, this
behaviour makes it unusable. The loop is finite and the counter doesn't
overflow, so this is a wrong code generated.
Tested revisions:
r162653 - fail
r162456 - OK
--
Summary: [4.6 Regression] -funsafe-loop-optimizations causes
FAIL: gcc.c-torture/execute/pr27285.c execution
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: zsojka at seznam dot cz
GCC host triplet: x86_64-pc-linux-gnu
GCC target triplet: x86_64-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45122
