Re: [PATCH 1/2] OpenMP/Fortran: Map intermediate array descriptor [PR120505]

On 16/02/2026 18:49, Tobias Burnus wrote:
> Paul-Antoine Arras wrote:
>> Please find attached a slightly amended version of the patch with 
>> OMP_CLAUSE_MAP_SIZE_NEEDS_ADJUSTMENT defined as a flag rather than a 
>> special value.
> 
> I misread one part of the patch – but it turned out be helpful,
> nonetheless, because the testcase I created fails (see attachment).
> 
> With current mainline (w/o offloading configured), the testcase passes
> (compiles and runs with host fallback).
> 
> However, with the 1/2 patch applied, it segfaults:
> 
> libgomp/testsuite/libgomp.fortran/map-subarray-13.f90:41:38:
> 
>     41 | !$omp   map(to: chunk%left_rcv_buffer)
>        |                                      ^
> internal compiler error: Segmentation fault
> 0x26213cd internal_error(char const*, ...)
>          ../../../repos/gcc/gcc/diagnostic-global-context.cc:787
> 0x123d12f crash_signal
>          ../../../repos/gcc/gcc/toplev.cc:325
> 0xec3ebe omp_build_struct_sibling_lists
>          ../../../repos/gcc/gcc/gimplify.cc:13421
> 0xed14b7 gimplify_adjust_omp_clauses
>          ../../../repos/gcc/gcc/gimplify.cc:15660
> 0xef11be gimplify_omp_target_update
>          ../../../repos/gcc/gcc/gimplify.cc:19054
> 
> 
> The testcase is a modified version of your testcase, *with some additional
> layers of allocatables added*.

Initially I crafted this patch for the "simple" case with only one 
intermediate descriptor, leaving the more complex cases for later -- and 
kind of forgot about it.

To support additional layers in the FE would probably mean saving in a 
vector all allocatables found while walking the chain of references. 
Then loop through the vector and call gfc_map_array_descriptor for each 
element. Hopefully that will just work with no changes in the ME.

If so, I'll come up with a revised version of the patch. Otherwise, if 
it entails much more work, what about putting sorry() there and leaving 
a note in the PR?

> The fail is because struct_node == NULL:
> 
> 13402         if (c != NULL && OMP_CLAUSE_CODE (c) == OMP_CLAUSE_MAP
> 13403             && OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_STRUCT
> 13404             && OMP_CLAUSE_MAP_KIND (OMP_CLAUSE_CHAIN (c)) == 
> GOMP_MAP_TO_PSET
> 13405             && OMP_CLAUSE_MAP_KIND (grp->grp_end) == 
> GOMP_MAP_ATTACH_DETACH
> 13406             && OMP_CLAUSE_MAP_SIZE_NEEDS_ADJUSTMENT (grp->grp_end))
> 13407           {
> ...
> 13420             tree *struct_node = struct_map_to_clause->get (base);
> 13421             omp_siblist_move_node_after (c, cp, &OMP_CLAUSE_CHAIN 
> (*struct_node));
> 
> 
> (gdb) p struct_node
> $11 = (tree *) 0x0
> 
> (gdb) p debug(c)
>   <omp_clause 0x7ffff727a2d0 constant map
>      op-0: <nop_expr 0x7ffff728a7a0>
>      op-1: <integer_cst 0x7ffff7402df8 0>
>      op-2:>
> $7 = void
> 
> (gdb) p c == *cp
> $9 = true
> 
> 
> (gdb) p debug(base)
>   <indirect_ref 0x7ffff7366a40
>      type <array_type 0x7ffff722f0a8
>          type <record_type 0x7ffff7223690 tile_type2 BLK
> ...
>      arg:0 <nop_expr 0x7ffff728a7a0
>          arg:0 <component_ref 0x7ffff7289b70 type <pointer_type 
> 0x7ffff7424738>
>              arg:0 <component_ref 0x7ffff7341210 type <record_type 
> 0x7ffff722f000 array01_tile_type2>
>                  arg:0 <var_decl 0x7ffff72324c0 chunk> arg:1 <field_decl 
> 0x7ffff7230140 tiles>
> 
> * * *
> 
> Testcase attached (modified version of your testcase).
> 
> Tobias


-- 
PA