[Patch, Fortran] Allocate + CAF library

[Daniel Carrera]

On 07/15/2011 02:16 PM, Tobias Burnus wrote:
>> 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.

Ok.


>> /* 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.

There are two if-branches and I'm not sure which one you are talking 
about. But let me tell you what I think we should do and you can tell me 
if we are on the same page:

I think we should move the entire "if (code->expr1 ...)" block outside 
the "if (!gfc_array_allocate)" block. In other words, I propose this:


if (!gfc_array_allocate (&se, expr, stat, errmsg, errlen))
   {
     ... allocate scalar ...
   }
if (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);
     ...
   }


My thinking is that this error checking applies equally whether the we 
use gfc_array_allocate or not. If we call gfc_array_allocate we still 
have stat, we still have errmsg, and we still may or may not call the 
coarray library. And I see nothing inside gfc_array_allocate that covers 
stat= and errmsg=.

What do you think?


> 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.

That would make sense if arrays always went into gfc_array_allocate. In 
that case, I think that my proposed change above would fix the problem.


> 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.

Yes, I'd like to do that next. It's very much related to what I've been 
doing lately. I think I even remember noticing that the code deallocated 
the previous array and was wondering why it did that.

Cheers,
Daniel.
-- 
I'm not overweight, I'm undertall.