Re: [PATCH,FORTRAN] Fix memory leak of gsymbol

[Harald Anlauf <anlauf@gmx.de>]

Hi Bernhard,

Am 27.10.21 um 23:43 schrieb Bernhard Reutner-Fischer via Gcc-patches:
> ping
> [I'll rebase and retest this too since it's been a while.
> Ok if it passes?]
>
> On Sun, 21 Oct 2018 16:04:34 +0200
> Bernhard Reutner-Fischer <rep.dot.nop@gmail.com> wrote:
>
>> Hi!
>>
>> Regtested on x86_64-unknown-linux, installing on
>> aldot/fortran-fe-stringpool.
>>
>> We did not free global symbols. For a simplified abstract_type_3.f03
>> valgrind reports:
>>
>> 96 bytes in 1 blocks are still reachable in loss record 461 of 602
>>     at 0x48377D5: calloc (vg_replace_malloc.c:711)
>>     by 0x21257C3: xcalloc (xmalloc.c:162)
>>     by 0x98611B: gfc_get_gsymbol(char const*) (symbol.c:4341)
>>     by 0x932C58: parse_module() (parse.c:5912)
>>     by 0x9336F8: gfc_parse_file() (parse.c:6236)
>>     by 0x991449: gfc_be_parse_file() (f95-lang.c:204)
>>     by 0x11D8EDE: compile_file() (toplev.c:455)
>>     by 0x11DB9C3: do_compile() (toplev.c:2170)
>>     by 0x11DBCAF: toplev::main(int, char**) (toplev.c:2305)
>>     by 0x2045D37: main (main.c:39)
>>
>> This patch reduces leaks to
>>
>>   LEAK SUMMARY:
>>      definitely lost: 344 bytes in 1 blocks
>>      indirectly lost: 3,024 bytes in 4 blocks
>>        possibly lost: 0 bytes in 0 blocks
>> -   still reachable: 1,576,174 bytes in 2,277 blocks
>> +   still reachable: 1,576,078 bytes in 2,276 blocks
>>           suppressed: 0 bytes in 0 blocks
>>
>> gcc/fortran/ChangeLog:
>>
>> 2018-10-21  Bernhard Reutner-Fischer  <aldot@gcc.gnu.org>
>>
>> 	* parse.c (clean_up_modules): Free gsym.
>> ---
>>   gcc/fortran/parse.c | 18 +++++++++++-------
>>   1 file changed, 11 insertions(+), 7 deletions(-)
>>
>> diff --git a/gcc/fortran/parse.c b/gcc/fortran/parse.c
>> index b7265c42f58..f7c369a17ac 100644
>> --- a/gcc/fortran/parse.c
>> +++ b/gcc/fortran/parse.c
>> @@ -6066,7 +6066,7 @@ resolve_all_program_units (gfc_namespace *gfc_global_ns_list)
>>
>>
>>   static void
>> -clean_up_modules (gfc_gsymbol *gsym)
>> +clean_up_modules (gfc_gsymbol *&gsym)
>>   {
>>     if (gsym == NULL)
>>       return;
>> @@ -6074,14 +6074,18 @@ clean_up_modules (gfc_gsymbol *gsym)
>>     clean_up_modules (gsym->left);
>>     clean_up_modules (gsym->right);
>>
>> -  if (gsym->type != GSYM_MODULE || !gsym->ns)
>> +  if (gsym->type != GSYM_MODULE)
>>       return;
>>
>> -  gfc_current_ns = gsym->ns;
>> -  gfc_derived_types = gfc_current_ns->derived_types;
>> -  gfc_done_2 ();
>> -  gsym->ns = NULL;
>> -  return;
>> +  if (gsym->ns)
>> +    {
>> +      gfc_current_ns = gsym->ns;
>> +      gfc_derived_types = gfc_current_ns->derived_types;
>> +      gfc_done_2 ();
>> +      gsym->ns = NULL;
>> +    }
>> +  free (gsym);
>> +  gsym = NULL;

this essentially looks fine, but did you inspect the callers?

With the change to the interface (*gsym -> *&gsym), it could have
effects not visible here due to the explicit gsym = NULL.

Assuming you checked that, and if it regtests fine, then it is
OK for mainline.

Thanks for the patch!

Harald

>>   }
>>
>>
>
>