On 11/8/18 9:56 AM, Martin Liška wrote:
> On 11/7/18 11:23 PM, Jeff Law wrote:
>> On 10/30/18 6:28 AM, Martin Liška wrote:
>>> On 10/30/18 11:03 AM, Jakub Jelinek wrote:
>>>> On Mon, Oct 29, 2018 at 04:14:21PM +0100, Martin Liška wrote:
>>>>> +hashtab_chk_error ()
>>>>> +{
>>>>> +  fprintf (stderr, "hash table checking failed: "
>>>>> +	   "equal operator returns true for a pair "
>>>>> +	   "of values with a different hash value");
>>>> BTW, either use internal_error here, or at least if using fprintf
>>>> terminate with \n, in your recent mail I saw:
>>>> ...different hash valueduring RTL pass: vartrack
>>>>                     ^^^^^^
>>> Sure, fixed in attached patch.
>>>
>>> Martin
>>>
>>>>> +  gcc_unreachable ();
>>>>> +}
>>>> 	Jakub
>>>>
>>>
>>> 0001-Sanitize-equals-and-hash-functions-in-hash-tables.patch
>>>
>>> From 0d9c979c845580a98767b83c099053d36eb49bb9 Mon Sep 17 00:00:00 2001
>>> From: marxin <mliska@suse.cz>
>>> Date: Mon, 29 Oct 2018 09:38:21 +0100
>>> Subject: [PATCH] Sanitize equals and hash functions in hash-tables.
>>>
>>> ---
>>>  gcc/hash-table.h | 40 +++++++++++++++++++++++++++++++++++++++-
>>>  1 file changed, 39 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/gcc/hash-table.h b/gcc/hash-table.h
>>> index bd83345c7b8..694eedfc4be 100644
>>> --- a/gcc/hash-table.h
>>> +++ b/gcc/hash-table.h
>>> @@ -503,6 +503,7 @@ private:
>>>  
>>>    value_type *alloc_entries (size_t n CXX_MEM_STAT_INFO) const;
>>>    value_type *find_empty_slot_for_expand (hashval_t);
>>> +  void verify (const compare_type &comparable, hashval_t hash);
>>>    bool too_empty_p (unsigned int);
>>>    void expand ();
>>>    static bool is_deleted (value_type &v)
>>> @@ -882,8 +883,12 @@ hash_table<Descriptor, Allocator>
>>>    if (insert == INSERT && m_size * 3 <= m_n_elements * 4)
>>>      expand ();
>>>  
>>> -  m_searches++;
>>> +#if ENABLE_EXTRA_CHECKING
>>> +    if (insert == INSERT)
>>> +      verify (comparable, hash);
>>> +#endif
>>>  
>>> +  m_searches++;
>>>    value_type *first_deleted_slot = NULL;
>>>    hashval_t index = hash_table_mod1 (hash, m_size_prime_index);
>>>    hashval_t hash2 = hash_table_mod2 (hash, m_size_prime_index);
>>> @@ -930,6 +935,39 @@ hash_table<Descriptor, Allocator>
>>>    return &m_entries[index];
>>>  }
>>>  
>>> +#if ENABLE_EXTRA_CHECKING
>>> +
>>> +/* Report a hash table checking error.  */
>>> +
>>> +ATTRIBUTE_NORETURN ATTRIBUTE_COLD
>>> +static void
>>> +hashtab_chk_error ()
>>> +{
>>> +  fprintf (stderr, "hash table checking failed: "
>>> +	   "equal operator returns true for a pair "
>>> +	   "of values with a different hash value\n");
>>> +  gcc_unreachable ();
>>> +}
>> I think an internal_error here is probably still better than a simple
>> fprintf, even if the fprintf is terminated with a \n :-)
> 
> Fully agree with that, but I see a lot of build errors when using internal_error.
> 
>>
>> The question then becomes can we bootstrap with this stuff enabled and
>> if not, are we likely to soon?  It'd be a shame to put it into
>> EXTRA_CHECKING, but then not be able to really use EXTRA_CHECKING
>> because we've got too many bugs to fix.
> 
> Unfortunately it's blocked with these 2 PRs:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87845
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87847

Hi.

I've just added one more PR:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90450

I'm sending updated version of the patch that provides a disablement for the 3 PRs
with a new function disable_sanitize_eq_and_hash.

With that I can bootstrap and finish tests. However, I've done that with a patch
limits maximal number of checks:

diff --git a/gcc/hash-table.h b/gcc/hash-table.h
index dc24fea6405..57564914e31 100644
--- a/gcc/hash-table.h
+++ b/gcc/hash-table.h
@@ -1027,7 +1027,7 @@ void
 hash_table<Descriptor, Lazy, Allocator>
 ::verify (const compare_type &comparable, hashval_t hash)
 {
-  for (size_t i = 0; i < m_size; i++)
+  for (size_t i = 0; i < MIN (m_size, 1000); i++)
     {
       value_type *entry = &m_entries[i];
       if (!is_empty (*entry) && !is_deleted (*entry)

Without that it would be probably terribly slow. Moreover, one probably does not want
that with an extra checking, but with an extra-extra checking. Ideas about where to enable
it?

Would it be possible to add the sanitization with the aforementioned disablement?

Thanks,
Martin

> 
> I'm fine with having the patch in in next stage1 after the problems will
> be fixed.
> 
> Martin
> 
>>
>>> +
>>> +/* Verify that all existing elements in th hash table which are
>> s/th/the/
>>
>>
>> Jeff
>>
>