Re: [Patch, Fortran] Allocate + CAF library

[Tobias Burnus <burnus at net-b dot de>]

On 07/15/2011 12:58 PM, Daniel Carrera wrote:
> > > + label_errmsg = gfc_build_label_decl (NULL_TREE);
> > > + label_finish = gfc_build_label_decl (NULL_TREE);
> >
> > There seems to be a goto missing.
>
> This is strange. The problem is definitely in the following if branch 
> in gfc_trans_array:
>
>   if (code->expr1 || code->expr2)
>     {

Side remark: One actually only needs to take care whether there is a 
STAT=. If there is only an ERRMSG=, the code is unreachable as without 
STAT= one gets a run-time error, when an error occurs - and if no error 
occurs, ERRMSG= is not modified. Thus, one could reduce the code size by 
checking only for code->expr1.


>       /* The coarray library already sets the errmsg.  */
>       if (gfc_option.coarray == GFC_FCOARRAY_LIB
> && gfc_expr_attr (expr).codimension)
>     tmp = build1_v (GOTO_EXPR, label_finish);
>       else
>     tmp = build1_v (GOTO_EXPR, label_errmsg);

OK, I understand now why. It is a bit convoluted - and it is due to an 
existing bug in GCC. All (allocatable) coarrays - including 
(allocatable) scalar coarrays are arrays - and arrays are handled in 
gfc_array_allocate.
The code to jump over the next items to the final or error label is only 
checked in the "!gfc_array_allocate" loop.

Thus:
- The code for jumping to the label needs to be either in an "else" 
branch or moved out of "if" branch.
- In the "if" branch, you can remove all coarray additions - and add a 
gcc_assert() to make sure that indeed no coarray enters there.

Seemingly, the "if (stat !=0) goto ..."  for arrays never worked - not 
in GCC 4.1, 4.3, 4.4, 4.6 nor in 4.7.

Tobias

PS: Another bug I found when looking at this patch is PR 49775, it is 
related to the code, but an independent issue. I think it will probably 
better to place it into a different patch. I was wondering whether you 
could/would/want to do it after this patch; it should be straight forward.