Re: hash-table violation in gcc/fortran/trans-decl.c

["Martin Liška" <mliska@suse.cz>]

On 10/31/18 10:40 AM, Trevor Saunders wrote:
> On Tue, Oct 30, 2018 at 11:07:16AM +0100, Martin Li??ka wrote:
>> On 10/29/18 12:04 PM, Martin Li??ka wrote:
>>> 2) gfc_find_module
>>>
>>> $ ./xgcc -B. /home/marxin/Programming/gcc/gcc/testsuite/gfortran.dg/coarray/alloc_comp_2.f90 -fcoarray=single -fchecking=3
>>> hash table checking failed: equal operator returns true for a pair of values with a different hash valuef951: internal compiler error: in find_slot_with_hash, at hash-table.h:905
>>> 0x8e5e86 hash_table<module_hasher, xcallocator>::find_slot_with_hash(char const* const&, unsigned int, insert_option)
>>> 	/home/marxin/Programming/gcc/gcc/hash-table.h:905
>>> 0x8e2c2c gfc_find_module(char const*)
>>> 	/home/marxin/Programming/gcc/gcc/fortran/trans-decl.c:4865
>>> 0x8e4f42 gfc_generate_module_vars(gfc_namespace*)
>>> 	/home/marxin/Programming/gcc/gcc/fortran/trans-decl.c:5475
>>> 0x8b8d7e gfc_generate_module_code(gfc_namespace*)
>>> 	/home/marxin/Programming/gcc/gcc/fortran/trans.c:2190
>>> 0x868427 translate_all_program_units
>>> 	/home/marxin/Programming/gcc/gcc/fortran/parse.c:6112
>>> 0x868427 gfc_parse_file()
>>> 	/home/marxin/Programming/gcc/gcc/fortran/parse.c:6328
>>> 0x8b19cb gfc_be_parse_file
>>> 	/home/marxin/Programming/gcc/gcc/fortran/f95-lang.c:204
>>
>> This one is real issue introduced in r216127, I'll post it to corresponding mailing list
>> after testing:
> 
> Yeah, sorry and lgtm.  I wonder if we could make htab_hash_string take a
> const char * to catch this sooner?

That happens.

Exactly my thoughts! The issue is that old C-style htab in libiberty expects
void *, so I can come up with a specific const char * specialization that
we can leverage in gcc internally (read with C++).

Martin

> 
> Trev
> 
>>
>> diff --git a/gcc/fortran/trans-decl.c b/gcc/fortran/trans-decl.c
>> index 88f9f570725..e8da9e11d22 100644
>> --- a/gcc/fortran/trans-decl.c
>> +++ b/gcc/fortran/trans-decl.c
>> @@ -4825,7 +4825,7 @@ struct module_hasher : ggc_ptr_hash<module_htab_entry>
>>  {
>>    typedef const char *compare_type;
>>  
>> -  static hashval_t hash (module_htab_entry *s) { return htab_hash_string (s); }
>> +  static hashval_t hash (module_htab_entry *s) { return htab_hash_string (s->name); }
>>    static bool
>>    equal (module_htab_entry *a, const char *b)
>>    {
>>
>> Martin