[GOMP4, OpenACC] Fixed-form Fortran code failing to parse

[Tobias Burnus]

Thomas Schwinge wrote:
> In -fopenmp mode as well as in  combined -fopenacc -fopenmp mode as
 > well as in "regular" (no -fopen*) mode, it parses fine.

[Note I am testing with an outdated branch (20140404), but it still 
might be representative.]

I am not sure it parses fine in the combined more. If I use

*$ACC xPARALLEL

i.e. add a typo, it fails to diagnose it in the combined mode. It does 
diagnose it for -fopenacc:

*$ACC xPARALLEL COPYIN(ARGC)
       1
Error: Unclassifiable OpenACC directive at (1)

And it does diagnose the problem for $OMP in only OpenMP and in combined 
mode.


> I couldn't find anything  obvious in gcc/fortran/parse.c; is someone
 > able to have a more in-depth look than I have?

First, some minor point, I think one should crosswise reset the 
{openmp,openacc}_flag, i.e.

--- a/gcc/fortran/scanner.c
+++ b/gcc/fortran/scanner.c
@@ -735,2 +735,3 @@ skip_oacc_attribute (locus start, locus old_loc, 
bool continue_flag)
               openacc_flag = 1;
+              openmp_flag = 0;
               openacc_locus = old_loc;
@@ -775,2 +776,3 @@ skip_omp_attribute (locus start, locus old_loc, bool 
continue_flag)
               openmp_flag = 1;
+             openacc_flag = 0;
               openmp_locus = old_loc;
@@ -826,3 +828,3 @@ skip_free_comments (void)
           /* Keep the !GCC$ line.  */
-                 if (at_bol && skip_gcc_attribute (start))
+         if (at_bol && skip_gcc_attribute (start))
             return false;


Secondly, the following looks wrong (also scanner.c). I have the feeling 
that this could be behind the issue above. But in any case, it looks 
wrong to me.


skip_fixed_comments (void)
...
       start = gfc_current_locus;
       c = next_char ();
       if (c == '!' || c == 'c' || c == 'C' || c == '*')
           if (gfc_option.gfc_flag_openmp)
             {
               if (next_char () == '$')
                 {
                   c = next_char ();
                   if (c == 'o' || c == 'O')
                     {
...
               gfc_current_locus = start;
...
             }

           if (gfc_option.gfc_flag_openacc)
             {
               if (next_char () == '$')
                 {

Namely: If "omp" or the "!$" continuation lines hasn't been matched, one 
returns to "start". However, start is "!" or "*" in this case and not 
"$". In addition, also in this case, one might want to set the other 
flag to 0.


My feeling is that the bug is also related to something in scanner.c.

Tobias

PS: I might try later to find out what goes wrong, but that requires in 
any case a binary which is not older than the source code.