Hi Tobias!
On 2023-11-08T17:58:10+0100, Tobias Burnus <[email protected]> wrote:
> OpenMP/Fortran: Implement omp allocators/allocate for ptr/allocatables
Nice work!
> This commit adds -fopenmp-allocators which enables support for
> 'omp allocators' and 'omp allocate' that are associated with a Fortran
> allocate-stmt. If such a construct is encountered, an error is shown,
> unless the -fopenmp-allocators flag is present.
>
> With -fopenmp -fopenmp-allocators, those constructs get turned into
> GOMP_alloc allocations, while -fopenmp-allocators (also without -fopenmp)
> ensures deallocation and reallocation (via intrinsic assignments) are
> properly directed to GOMP_free/omp_realloc - while normal Fortran
> allocations are processed by free/realloc.
>
> In order to distinguish a 'malloc'ed from a 'GOMP_alloc'ed memory, the
> version field of the Fortran array discriptor is (mis)used: 0 indicates
> the normal Fortran allocation while 1 denotes GOMP_alloc. For scalars,
> there is record keeping in libgomp: GOMP_add_alloc(ptr) will add the
> pointer address to a splay_tree while GOMP_is_alloc(ptr) will return
> true it was previously added but also removes it from the list.
>
> Besides Fortran FE work, BUILT_IN_GOMP_REALLOC is no part of
> omp-builtins.def and libgomp gains the mentioned two new function.
Minor comments:
> --- a/gcc/fortran/trans-openmp.cc
> +++ b/gcc/fortran/trans-openmp.cc
> +/* Add ptr for tracking as being allocated by GOMP_alloc. */
> +
> +tree
> +gfc_omp_call_add_alloc (tree ptr)
> +{
> + static tree fn = NULL_TREE;
> + if (fn == NULL_TREE)
> + {
> + fn = build_function_type_list (void_type_node, ptr_type_node,
> NULL_TREE);
> + fn = build_fn_decl ("GOMP_add_alloc", fn);
> +/* FIXME: attributes. */
> + }
> + return build_call_expr_loc (input_location, fn, 1, ptr);
> +}
> +
> +/* Generated function returns true when it was tracked via GOMP_add_alloc and
> + removes it from the tracking. As called just before GOMP_free or
> omp_realloc
> + the pointer is or might become invalid, thus, it is always removed. */
> +
> +tree
> +gfc_omp_call_is_alloc (tree ptr)
> +{
> + static tree fn = NULL_TREE;
> + if (fn == NULL_TREE)
> + {
> + fn = build_function_type_list (boolean_type_node, ptr_type_node,
> + NULL_TREE);
> + fn = build_fn_decl ("GOMP_is_alloc", fn);
> +/* FIXME: attributes. */
> + }
> + return build_call_expr_loc (input_location, fn, 1, ptr);
> +}
Why not define 'GOMP_add_alloc', 'GOMP_is_alloc' via
'gcc/omp-builtins.def'?
> --- a/gcc/omp-builtins.def
> +++ b/gcc/omp-builtins.def
> @@ -467,6 +467,9 @@ DEF_GOMP_BUILTIN
> (BUILT_IN_GOMP_WORKSHARE_TASK_REDUCTION_UNREGISTER,
> DEF_GOMP_BUILTIN (BUILT_IN_GOMP_ALLOC,
> "GOMP_alloc", BT_FN_PTR_SIZE_SIZE_PTRMODE,
> ATTR_ALLOC_WARN_UNUSED_RESULT_SIZE_2_NOTHROW_LIST)
> +DEF_GOMP_BUILTIN (BUILT_IN_GOMP_REALLOC,
> + "omp_realloc", BT_FN_PTR_PTR_SIZE_PTRMODE_PTRMODE,
> + ATTR_ALLOC_WARN_UNUSED_RESULT_SIZE_2_NOTHROW_LEAF_LIST)
> DEF_GOMP_BUILTIN (BUILT_IN_GOMP_FREE,
> "GOMP_free", BT_FN_VOID_PTR_PTRMODE, ATTR_NOTHROW_LEAF_LIST)
> DEF_GOMP_BUILTIN (BUILT_IN_GOMP_WARNING, "GOMP_warning",
Should this either be 'BUILT_IN_OMP_REALLOC' ('OMP' instead of 'GOMP'),
or otherwise a 'GOMP_realloc' be added to 'libgomp/allocator.c', like for
'GOMP_alloc', 'GOMP_free'; 'ialias_call'ing the respective 'omp_[...]'
functions? (Verbatim 'omp_realloc' also mentioned in the comment before
'gcc/fortran/trans-openmp.cc:gfc_omp_call_is_alloc'.)
> --- a/libgomp/allocator.c
> +++ b/libgomp/allocator.c
> +/* Add pointer as being alloced by GOMP_alloc. */
> +void
> +GOMP_add_alloc (void *ptr)
> +{
> + [...]
> +}
> +
> +/* Remove pointer, either called by FREE or by REALLOC,
> + either of them can change the allocation status. */
> +bool
> +GOMP_is_alloc (void *ptr)
> +{
> + [...]
> +}
> --- a/libgomp/libgomp.map
> +++ b/libgomp/libgomp.map
> +GOMP_5.1.2 {
> + global:
> + GOMP_add_alloc;
> + GOMP_is_alloc;
> + [...]
> +} GOMP_5.1.1;
'GOMP_add_alloc', 'GOMP_is_alloc' should get prototyped in
'libgomp/libgomp_g.h'.
Grüße
Thomas
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