Re: [PATCH] operand_equal_p checking (PR sanitizer/70683)

[Christophe Lyon <christophe.lyon@linaro.org>]

Hi,
This caused: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70843

On 27 April 2016 at 14:41, Richard Biener <rguenther@suse.de> wrote:
> On Wed, 27 Apr 2016, Jakub Jelinek wrote:
>
>> On Tue, Apr 26, 2016 at 03:02:38PM +0200, Jakub Jelinek wrote:
>> > The debugging hack is too ugly and slows down the compiler (by artificially
>> > increasing number of collisions), so it is not appropriate, but perhaps we
>> > can add some internal only use OEP_* flag, pass it to the recursive calls
>> > of operand_equal_p and if not set and flag_checking, verify
>> > iterative_hash_expr equality in the outermost call).
>>
>> Here is the corresponding checking patch.  It uncovered two further issues
>> in the tree.[ch] patch which I'm going to post momentarily.
>> Both patches together bootstrapped/regtested on x86_64-linux and i686-linux,
>> ok for trunk?
>
> Ok.
>
> Thanks,
> Richard.
>
>> 2016-04-27  Jakub Jelinek  <jakub@redhat.com>
>>
>>       PR sanitizer/70683
>>       * tree-core.h (enum operand_equal_flag): Add OEP_NO_HASH_CHECK.
>>       * fold-const.c (operand_equal_p): If flag_checking and
>>       OEP_NO_HASH_CHECK is not set in flag, recurse with OEP_NO_HASH_CHECK
>>       and if it returns non-zero, assert iterative_hash_expr on both
>>       args is the same.
>>
>> --- gcc/tree-core.h.jj        2016-04-22 18:21:55.000000000 +0200
>> +++ gcc/tree-core.h   2016-04-26 17:47:19.875753297 +0200
>> @@ -765,7 +765,9 @@ enum operand_equal_flag {
>>    OEP_ONLY_CONST = 1,
>>    OEP_PURE_SAME = 2,
>>    OEP_MATCH_SIDE_EFFECTS = 4,
>> -  OEP_ADDRESS_OF = 8
>> +  OEP_ADDRESS_OF = 8,
>> +  /* Internal within operand_equal_p:  */
>> +  OEP_NO_HASH_CHECK = 16
>>  };
>>
>>  /* Enum and arrays used for tree allocation stats.
>> --- gcc/fold-const.c.jj       2016-04-22 18:21:32.000000000 +0200
>> +++ gcc/fold-const.c  2016-04-26 18:30:40.919080701 +0200
>> @@ -2749,6 +2749,25 @@ combine_comparisons (location_t loc,
>>  int
>>  operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
>>  {
>> +  /* When checking, verify at the outermost operand_equal_p call that
>> +     if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
>> +     hash value.  */
>> +  if (flag_checking && !(flags & OEP_NO_HASH_CHECK))
>> +    {
>> +      if (operand_equal_p (arg0, arg1, flags | OEP_NO_HASH_CHECK))
>> +     {
>> +       inchash::hash hstate0 (0), hstate1 (0);
>> +       inchash::add_expr (arg0, hstate0, flags);
>> +       inchash::add_expr (arg1, hstate1, flags);
>> +       hashval_t h0 = hstate0.end ();
>> +       hashval_t h1 = hstate1.end ();
>> +       gcc_assert (h0 == h1);
>> +       return 1;
>> +     }
>> +      else
>> +     return 0;
>> +    }
>> +
>>    /* If either is ERROR_MARK, they aren't equal.  */
>>    if (TREE_CODE (arg0) == ERROR_MARK || TREE_CODE (arg1) == ERROR_MARK
>>        || TREE_TYPE (arg0) == error_mark_node
>>
>>
>>       Jakub
>>
>>
>
> --
> Richard Biener <rguenther@suse.de>
> SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)