Re: [Patch] OpenMP: Fix use_device_{addr,ptr} with in-data-sharing arg

[Jakub Jelinek <jakub@redhat.com>]

On Wed, Apr 20, 2022 at 03:19:38PM +0200, Tobias Burnus wrote:
> For array-descriptor vars, the descriptor is assigned to a temporary. However,
> this failed when the clause's argument was in turn in a data-sharing clause
> as the outer context's VALUE_EXPR wasn't used.
> 
> gcc/ChangeLog:
> 
> 	* omp-low.cc (lower_omp_target): Fix use_device_{addr,ptr} with list
> 	item that is in an outer data-sharing clause.
> 
> libgomp/ChangeLog:
> 
> 	* testsuite/libgomp.fortran/use_device_addr-5.f90: New test.
> 
>  gcc/omp-low.cc                                     |  22 ++--
>  .../libgomp.fortran/use_device_addr-5.f90          | 143 +++++++++++++++++++++
>  2 files changed, 156 insertions(+), 9 deletions(-)
> 
> diff --git a/gcc/omp-low.cc b/gcc/omp-low.cc
> index bf5779b6543..6e387fd9a61 100644
> --- a/gcc/omp-low.cc
> +++ b/gcc/omp-low.cc
> @@ -13656,26 +13656,30 @@ lower_omp_target (gimple_stmt_iterator *gsi_p, omp_context *ctx)
>  		new_var = lookup_decl (var, ctx);
>  		new_var = DECL_VALUE_EXPR (new_var);
>  		tree v = new_var;
> +		tree v2 = var;
> +		if (OMP_CLAUSE_CODE (c) == OMP_CLAUSE_USE_DEVICE_PTR
> +		    || OMP_CLAUSE_CODE (c) == OMP_CLAUSE_USE_DEVICE_ADDR)
> +		  {
> +		    v2 = maybe_lookup_decl_in_outer_ctx (var, ctx);
> +		    if (DECL_HAS_VALUE_EXPR_P (v2))
> +		      v2 = DECL_VALUE_EXPR (v2);

I don't understand the above 2 lines, why do you need that?
Regardless whether v2 has DECL_VALUE_EXPR or not, the type of the
DECL_VALUE_EXPR (v2) and v2 should be the same, build_fold_indirect_ref
should work on both and then v2 is only used as second operand of
gimplify_assign, where the gimplifier makes sure to handle DECL_VALUE_EXPR
correctly.  I certainly don't see any difference in the *.omplower dump
if I comment out the above 2 lines.

Otherwise LGTM, so if the 2 lines aren't needed, please also drop the
{}s around v2 = maybe_lookup_decl_in_outer_ctx (var, ctx); and reindent.

> +		  }
>  
>  		if (is_ref)
>  		  {
> -		    var = build_fold_indirect_ref (var);
> -		    gimplify_expr (&var, &assign_body, NULL, is_gimple_val,
> -				   fb_rvalue);
> -		    v = create_tmp_var_raw (TREE_TYPE (var), get_name (var));
> +		    v2 = build_fold_indirect_ref (v2);
> +		    v = create_tmp_var_raw (TREE_TYPE (v2), get_name (var));
>  		    gimple_add_tmp_var (v);
>  		    TREE_ADDRESSABLE (v) = 1;
> -		    gimple_seq_add_stmt (&assign_body,
> -					 gimple_build_assign (v, var));
> +		    gimplify_assign (v, v2, &assign_body);
>  		    tree rhs = build_fold_addr_expr (v);
>  		    gimple_seq_add_stmt (&assign_body,
>  					 gimple_build_assign (new_var, rhs));
>  		  }
>  		else
> -		  gimple_seq_add_stmt (&assign_body,
> -				       gimple_build_assign (new_var, var));
> +		  gimplify_assign (new_var, v2, &assign_body);
>  
> -		tree v2 = lang_hooks.decls.omp_array_data (unshare_expr (v), false);
> +		v2 = lang_hooks.decls.omp_array_data (unshare_expr (v), false);
>  		gcc_assert (v2);
>  		gimplify_expr (&x, &assign_body, NULL, is_gimple_val, fb_rvalue);
>  		gimple_seq_add_stmt (&assign_body,

	Jakub