[Bug c++/119102] GCC 15.0 'import std;' fails with Ofast (not with O3) due to some openmp internal error

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119102

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
It can be reproduced even with just simple foo.H
int foo (int) __attribute__((simd ("notinbranch")));
and foo.C
import "foo.H";
int main () {}
./xg++ -B ./ -Ofast -fmodule-header foo.H
./xg++ -B ./ -Ofast -fmodules foo.C -S
In module imported at foo.C:1:1:
./foo.H: error: module contains OpenMP, use ‘-fopenmp’ to enable
./foo.H: error: failed to read compiled module: Bad file data
./foo.H: note: compiled module file is ‘gcm.cache/,/foo.H.gcm’
./foo.H: fatal error: returning to the gate for a mechanical issue
compilation terminated.

Doesn't reproduce with just __attribute__((simd)) though.

The SE_OPENMP diagnostic is for some strange reason keyed on streaming out and
in OMP_CLAUSE.
Which is not a good idea.
OMP_CLAUSE can be created even for the simd attribute with argument:
          if (strcmp (TREE_STRING_POINTER (id), "notinbranch") == 0)
            attr = build_omp_clause (DECL_SOURCE_LOCATION (*node),
                                     OMP_CLAUSE_NOTINBRANCH);
          else if (strcmp (TREE_STRING_POINTER (id), "inbranch") == 0)
            attr = build_omp_clause (DECL_SOURCE_LOCATION (*node),
                                     OMP_CLAUSE_INBRANCH);
On the other side, when one actually uses some OpenMP construct without any
clauses, say bar.H
extern void bar ();
inline int
foo ()
{
  #pragma omp parallel
  bar ();
  return 0;
}
and bar.C
import "bar.H";
int main () { foo (); }
./cc1plus -quiet bar.H -fopenmp -fmodule-header
./cc1plus -quiet -fmodules bar.C -fdump-tree-gimple
during GIMPLE pass: *build_cgraph_edges
In module ./bar.H, imported at bar.C:1:
bar.H: In function ‘int foo()’:
bar.H:3:1: internal compiler error: Segmentation fault
    3 | foo ()
      | ^~~
0x30530a1 internal_error(char const*, ...)
        ../../gcc/diagnostic-global-context.cc:517
0x11d0928 crash_signal
        ../../gcc/toplev.cc:322
0x449b9d cgraph_node::get(tree_node const*)
        ../../gcc/cgraph.h:1346
0xaa4bcb cgraph_node::get_create(tree_node*)
        ../../gcc/cgraph.cc:537
0xab67db execute
        ../../gcc/cgraphbuild.cc:346
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