[Bug middle-end/115574] New: [OpenMP] Nested C function – 'declare target link(var)' leads to "referenced in offloaded code but hasn't been marked to be included in the offloaded code"

[Bug middle-end/115574] New: [OpenMP] Nested C function – 'declare target link(var)' leads to "referenced in offloaded code but hasn't been marked to be included in the offloaded code"

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115574

            Bug ID: 115574
           Summary: [OpenMP] Nested C function – 'declare target
                    link(var)' leads to "referenced in offloaded code but
                    hasn't been marked to be included in the offloaded
                    code"
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: openmp, rejects-valid
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: jakub at gcc dot gnu.org
  Target Milestone: ---

C variant for the issue PR 115559.

[Nested functions are a GNU extension - thus, we may decide not to fix this.]


Nonetheless, the following compiles but fails during device LTO:
foo.c:2:13: error: variable 'a' has been referenced in offloaded code but
hasn't been marked to be included in the offloaded code
    2 |  static int a, b[5];
      |             ^
foo.c:2:16: error: variable 'b' has been referenced in offloaded code but
hasn't been marked to be included in the offloaded code
    2 |  static int a, b[5];


void f() {
 static int a, b[5];
 #pragma declare target link(a,b)

void g() {  a = 7; b[3] = 3; }
// #pragma omp declare target enter(g)

 #pragma omp target map(tofrom: a, b)
   g();
}



The problem is the global-var check in c/c-parser.cc (and cp/parser.cc):

          id = get_identifier ("omp declare target link");
          std::swap (at1, at2);
        }
...
      if (!at1)
        {
          DECL_ATTRIBUTES (t) = tree_cons (id, NULL_TREE, DECL_ATTRIBUTES (t));
          if (TREE_CODE (t) != FUNCTION_DECL && !is_global_var (t))
            continue;
          symtab_node *node = symtab_node::get (t);
          if (node != NULL)
            {
              node->offloadable = 1;
...
                    vec_safe_push (offload_vars, t);


As neither is a global var, it is not added.

[Bug middle-end/115574] [OpenMP] Nested C function – 'declare target link(var)' leads to "referenced in offloaded code but hasn't been marked to be included in the offloaded code"

[tschwinge at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115574

Thomas Schwinge <tschwinge at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tschwinge at gcc dot gnu.org

--- Comment #1 from Thomas Schwinge <tschwinge at gcc dot gnu.org> ---
(Just noting that fixing the code à la '-Wunknown-pragmas' doesn't seem to make
a difference re the 'error' diagnostics.)

[Bug middle-end/115574] [OpenMP] Nested C function – 'declare target link(var)' leads to "referenced in offloaded code but hasn't been marked to be included in the offloaded code"

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115574

--- Comment #2 from Tobias Burnus <burnus at gcc dot gnu.org> ---
> #pragma declare target link(a,b)

as Thomas pointed out (cf. comment 1), an 'omp' is missing.
It also lacks, e.g. '#pragma omp target enter data map(a, b)' to be valid.

Still, the real issue is '!is_global_var (t)' which is only valid if there is
no nested function which is 'declare target', as that can access the static
variable through the backdoor.