Re: [PATCH] PR 78534 Change character length from int to size_t

[Janne Blomqvist <blomqvist dot janne at gmail dot com>]

On Mon, Dec 12, 2016 at 9:39 PM, Janne Blomqvist
<blomqvist.janne@gmail.com> wrote:
> On Mon, Dec 12, 2016 at 7:39 PM, Andre Vehreschild <vehre@gmx.de> wrote:
>> Hi Janne,
>>
>> I found that you are favoring build_int_cst (size_type_node, 0) over
>> size_zero_node. Is there a reason to this?
>
> Yes. AFAIU size_zero_node is a zero constant for sizetype which is not
> the same as size_type_node.
>
> AFAIK the difference is that size_type_node is the C size_t type,
> whereas sizetype is a GCC internal type used for address expressions.
> On a "normal" target I understand that they are the same size, but
> there are some slight differences in semantics, e.g. size_type_node
> like C unsigned integer types is defined to wrap around on overflow
> whereas sizetype is undefined on overflow.
>
> I don't know if GCC supports some strange targets with some kind of
> segmented memory where the size of sizetype would be different from
> size_type_node, but I guess it's possible in theory at least.
>
> That being said, now that you mention in I should be using
> build_zero_cst (some_type_node) instead of
> build_int_cst(some_type_node, 0). There's also build_one_cst that I
> should use.
>
>> Furthermore did I have to patch this:
>>
>> diff --git a/gcc/fortran/dump-parse-tree.c b/gcc/fortran/dump-parse-tree.c
>> index 585f25d..f374558 100644
>> --- a/gcc/fortran/dump-parse-tree.c
>> +++ b/gcc/fortran/dump-parse-tree.c
>> @@ -465,7 +465,7 @@ show_expr (gfc_expr *p)
>>           break;
>>
>>         case BT_HOLLERITH:
>> -         fprintf (dumpfile, "%dH", p->representation.length);
>> +         fprintf (dumpfile, "%zdH", p->representation.length);
>>           c = p->representation.string;
>>           for (i = 0; i < p->representation.length; i++, c++)
>>             {
>>
>> to bootstrap on x86_64-linux/f23.
>
> Ah, thanks for the catch. I'll fix it by using HOST_WIDE_INT_PRINT_DEC
> since I'll have to change gfc_charlen_t to be a typedef form
> HOST_WIDE_INT (see my answer to FX).
>
>> And I have this regression:
>>
>> FAIL: gfortran.dg/allocate_deferred_char_scalar_1.f03   -O1  (test for excess
>> errors)
>>
>> allocate_deferred_char_scalar_1.f03:184:0:
>>
>>      p = '12345679'
>>
>> Warning: '__builtin_memcpy' writing 8 bytes into a region of size 5 overflows
>>      the destination [-Wstringop-overflow=]
>>      allocate_deferred_char_scalar_1.f03:242:0:
>>
>>      p = 4_'12345679'
>>
>> Warning: '__builtin_memcpy' writing 32 bytes into a region of size 20 overflows
>> the destination [-Wstringop-overflow=]
>
> I'm seeing that too, but I assumed they would be fixed by Paul's
> recent patch which I don't yet have in my tree yet due to the git
> mirror being stuck..
>
>> Btw, the patch for changing the ABI of the coarray-libs is already nearly done.
>> I just need to figure that what the state of regressions is with and without my
>> change.
>
> Thanks.
>
> I'll produce an updated patch with the changes discussed so far.
>
>
> --
> Janne Blomqvist

Hi,

attached is the updated patch that applies on top of the original. I
didn't do the charlen_zero_node etc, I just fixed the relatively few
places in my previous patch rather than everywhere in the entire
frontend.

Now that the git mirror is working again, I see though those warnings
with -O1 from gfortran.dg/allocate_deferred_char_scalar_1.f03 are
still there, and Paul's patch didn't get rid of them. :(. I have
looked at the tree dumps, however, and AFAICS it's a bogus warning.

Ok for trunk?

-- 
Janne Blomqvist

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