[Bug other/39591] New: GOMP_loop_end illegally optmized into GOMP_loop_end_nowait

[Bug other/39591] New: GOMP_loop_end illegally optmized into GOMP_loop_end_nowait

[brian dot e dot bliss at intel dot com]

As the following example shows, this optimization cannot be performed legally
if the parallel loop spawns tasks which reference vars local to the parallel
region.  Without the optimization, all tasks would be executed at the implicit
barrier at the end of the loop (where "array" is still intact) rather than the
barrier at the end of the parallel region (thread 0's stack has been popped and
"array" deallocated).

% gcc -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: /net/gnu-13/export/gnu/src/gcc/gcc/configure --enable
clocale=gnu --with-system-zlib --enable-checking=assert --with-demangler-in-ld
--enable-shared --enable-threads=posix --enable-haifa --prefix=/usr/gcc4.4
--with-local-prefix=/usr/local
Thread model: posix
gcc version 4.4.0 20090311 (experimental) [trunk revision 144788] (GCC)
% cat test.c

#include <stdlib.h>
#include <stdio.h>
#include <omp.h>

int flag = 0;

int foo(int *array)
{
    int i;
    printf("array = %p\n", array);
    for (i = 0; i < 10; i++) {
        printf("i: %d 0x%x\n", i, array[i]);
    }
}

int main(int argc, char *argv[])
{

#pragma omp parallel shared(argc)
    {
        int array[10];
        int i;
        for (i = 0; i < 10; i++) {
            array[i] = 0x55555555;
        }

#pragma omp for schedule(dynamic)
        for (i = 0; i < argc; i++)

#pragma omp task default(shared) firstprivate(i)
        {
            if (omp_get_thread_num() == 0) {
                if (! flag) {
#pragma omp critical(cs)
                    foo(array);
                    flag = 1;
                }
            }
            else {
                sleep(1);
            }
#pragma omp critical(cs)
            printf("i = %d\n", i);
        }
    }
}
%
% gcc -fopenmp test.c
% a.out x x x
array = 0xf75bf380
i: 0 0x55555555
i: 1 0x55555555
i: 2 0x55555555
i: 3 0x1312d00
i: 4 0x55555555
i: 5 0x55555555
i: 6 0x55555555
i: 7 0xf7ffc908
i: 8 0xffffffcc
i: 9 0x804872c
i = 3
i = 2
i = 1
i = 0
% nm a.out | grep GOMP_loop
         U GOMP_loop_dynamic_next@@GOMP_1.0
         U GOMP_loop_dynamic_start@@GOMP_1.0
         U GOMP_loop_end_nowait@@GOMP_1.0
%


-- 
           Summary: GOMP_loop_end illegally optmized into
                    GOMP_loop_end_nowait
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: other
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: brian dot e dot bliss at intel dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39591

[Bug other/39591] GOMP_loop_end illegally optmized into GOMP_loop_end_nowait

[jakub at gcc dot gnu dot org]

-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jakub at gcc dot gnu dot org
                   |dot org                     |
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-03-30 22:19:19
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39591

[Bug other/39591] GOMP_loop_end illegally optmized into GOMP_loop_end_nowait

[jakub at gcc dot gnu dot org]

------- Comment #1 from jakub at gcc dot gnu dot org  2009-04-01 06:55 -------
Subject: Bug 39591

Author: jakub
Date: Wed Apr  1 06:54:52 2009
New Revision: 145390

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=145390
Log:
        PR other/39591
        * omp-low.c (remove_exit_barrier): Don't optimize if there are any
        addressable variables in the parallel that could go out of scope while
        running queued tasks.

        * testsuite/libgomp.c/pr39591-1.c: New test.
        * testsuite/libgomp.c/pr39591-2.c: New test.
        * testsuite/libgomp.c/pr39591-3.c: New test.

Added:
    trunk/libgomp/testsuite/libgomp.c/pr39591-1.c
    trunk/libgomp/testsuite/libgomp.c/pr39591-2.c
    trunk/libgomp/testsuite/libgomp.c/pr39591-3.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/omp-low.c
    trunk/libgomp/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39591

[Bug other/39591] GOMP_loop_end illegally optmized into GOMP_loop_end_nowait

[jakub at gcc dot gnu dot org]

------- Comment #2 from jakub at gcc dot gnu dot org  2009-04-01 07:06 -------
Subject: Bug 39591

Author: jakub
Date: Wed Apr  1 07:06:12 2009
New Revision: 145391

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=145391
Log:
        PR other/39591
        * omp-low.c (remove_exit_barrier): Don't optimize if there are any
        addressable variables in the parallel that could go out of scope while
        running queued tasks.

        * testsuite/libgomp.c/pr39591-1.c: New test.
        * testsuite/libgomp.c/pr39591-2.c: New test.
        * testsuite/libgomp.c/pr39591-3.c: New test.

Added:
    branches/gcc-4_4-branch/libgomp/testsuite/libgomp.c/pr39591-1.c
      - copied unchanged from r145390,
trunk/libgomp/testsuite/libgomp.c/pr39591-1.c
    branches/gcc-4_4-branch/libgomp/testsuite/libgomp.c/pr39591-2.c
      - copied unchanged from r145390,
trunk/libgomp/testsuite/libgomp.c/pr39591-2.c
    branches/gcc-4_4-branch/libgomp/testsuite/libgomp.c/pr39591-3.c
      - copied unchanged from r145390,
trunk/libgomp/testsuite/libgomp.c/pr39591-3.c
Modified:
    branches/gcc-4_4-branch/gcc/ChangeLog
    branches/gcc-4_4-branch/gcc/omp-low.c
    branches/gcc-4_4-branch/libgomp/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39591

[Bug other/39591] GOMP_loop_end illegally optmized into GOMP_loop_end_nowait

[jakub at gcc dot gnu dot org]

------- Comment #3 from jakub at gcc dot gnu dot org  2009-04-01 09:13 -------
Fixed.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39591