[PATCH, C++] Wrap OpenACC wait in EXPR_STMT

[Thomas Schwinge]

Hi Chung-Lin!

On Mon, 23 Nov 2015 21:15:00 +0800, Chung-Lin Tang <cltang@codesourcery.com> wrote:
> The OpenACC wait directive is represented as a call to the runtime
> function "GOACC_wait" instead of a tree code.  I am seeing when
> '#pragma acc wait' is using inside a template function, the CALL_EXPR
> to GOACC_wait is being silently ignored/removed during tsubst_expr().

Uh.

> I think the correct way to organize this is that the call should be inside
> an EXPR_STMT, so here's a patch to do that; basically remove the
> add_stmt() call from the shared c_finish_oacc_wait() code, and add
> add_stmt()/finish_expr_stmt() in the corresponding C/C++ parts.
> 
> Tested with no regressions on trunk, okay to commit?

> --- c-family/c-omp.c	(revision 230703)
> +++ c-family/c-omp.c	(working copy)
> @@ -63,7 +63,6 @@ c_finish_oacc_wait (location_t loc, tree parms, tr
>      }
>  
>    stmt = build_call_expr_loc_vec (loc, stmt, args);
> -  add_stmt (stmt);
>  
>    vec_free (args);
|  
|    return stmt;
|  }

I see in gcc/c/c-omp.c that several other c_finish_omp_* functions that
build builtin calls instead of tree nodes, do similar things like
c_finish_oacc_wait; I'd like to understand why it's -- presumably -- not
a problem for these: c_finish_omp_barrier, c_finish_omp_taskwait,
c_finish_omp_taskyield, c_finish_omp_flush?  (Jakub?)

> --- c/c-parser.c	(revision 230703)
> +++ c/c-parser.c	(working copy)
> @@ -13886,6 +13886,7 @@ c_parser_oacc_wait (location_t loc, c_parser *pars
>    strcpy (p_name, " wait");
>    clauses = c_parser_oacc_all_clauses (parser, OACC_WAIT_CLAUSE_MASK, p_name);
>    stmt = c_finish_oacc_wait (loc, list, clauses);
> +  add_stmt (stmt);
>  
>    return stmt;
>  }
> --- cp/parser.c	(revision 230703)
> +++ cp/parser.c	(working copy)
> @@ -34930,6 +34930,7 @@ cp_parser_oacc_wait (cp_parser *parser, cp_token *
>  					"#pragma acc wait", pragma_tok);
>  
>    stmt = c_finish_oacc_wait (loc, list, clauses);
> +  stmt = finish_expr_stmt (stmt);
>  
>    return stmt;
>  }


Grüße
 Thomas
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