[Bug libgomp/71844] New: Data mapping of an array section in the target construct

["ka6ash at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71844

            Bug ID: 71844
           Summary: Data mapping of an array section in the target
                    construct
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libgomp
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ka6ash at gmail dot com
                CC: jakub at gcc dot gnu.org
  Target Milestone: ---

Hi,

the following code from OpenMP examples 4.0.2(Section 58.3) causes an execution
error. I suppose the problem is that the _target_ construct tries to map A[30]
instead of using A[0:4]. 

The testsuit for libgomp contains a similar testcase but it has an additional
_map_ clause for A:

libgomp/testsuite/libgomp.c/examples-4/array_sections-4.c

#pragma omp target map(p[7:20]) map(A[0:4])

*** Example code
void foo ()
{
  int A[30], *p;
  #pragma omp target data map(A[0:4])
    {
      p = &A[0];
      #pragma omp target map(p[7:20])
        {
          A[2] = 777;
          p[8] = 777;
        }
    }

  if (A[2] != 777 || A[8] != 777)
    printf("FAIL\n");
}

*** Compilation flags
$ x86_64-pc-linux-gnu-gcc -O2 -fopenmp source.c

*** Error message
libgomp: Trying to map into device [0x7fff9538a420..0x7fff9538a498) object when
[0x7fff9538a420..0x7fff9538a430) is already mapped

*** GCC 
$x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/install/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/install/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
OFFLOAD_TARGET_NAMES=x86_64-intelmicemul-linux-gnu
Target: x86_64-pc-linux-gnu
Configured with: ../configure --disable-multilib
--enable-languages=c,c++,fortran,lto --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=x86_64-pc-linux-gnu
--enable-offload-targets=x86_64-intelmicemul-linux-gnu --disable-bootstrap
Thread model: posix
gcc version 7.0.0 20160711 (experimental) (GCC)