On Thu, Jun 29, 2017 at 10:23 PM, Martin Sebor <mse...@gmail.com> wrote:
> On 06/29/2017 10:15 AM, Jan Hubicka wrote:
>>
>> Hello,
>>>
>>> diff --git a/gcc/hash-table.h b/gcc/hash-table.h
>>> index 0f7e21a..443d16c 100644
>>> --- a/gcc/hash-table.h
>>> +++ b/gcc/hash-table.h
>>> @@ -803,7 +803,10 @@ hash_table<Descriptor, Allocator>::empty_slow ()
>>> m_size_prime_index = nindex;
>>> }
>>> else
>>> - memset (entries, 0, size * sizeof (value_type));
>>> + {
>>> + for ( ; size; ++entries, --size)
>>> + *entries = value_type ();
>>> + }
>>> m_n_deleted = 0;
>>> m_n_elements = 0;
>>> }
>>
>>
>> This change sends our periodic testers into an infinite loop. It is fault
>> of gcc 4.2 being used
>> as bootstrap compiler, but perhaps that can be worked around?
>
>
> The warning in the original code could have been suppressed (by
> casting the pointer to char*), but it was valid so I opted not
> to. I'd expect it to be possible to work around the bug but
> I don't have easy access to GCC 4.2 to reproduce it or verify
> the fix.
>
> FWIW, after looking at the function again, I wondered if zeroing
> out the elements (either way) was the right thing to do and if
> they shouldn't be cleared by calling Descriptor::mark_empty()
> instead, like in alloc_entries(), but making that change broke
> a bunch of ipa/ipa-pta-*.c tests. It's not really clear to me
> what this code is supposed to do.
>
> Martin
>
> PS Does this help at all?
>
> @@ -804,8 +804,8 @@ hash_table<Descriptor, Allocator>::empty_slow ()
> }
> else
> {
> - for ( ; size; ++entries, --size)
> - *entries = value_type ();
> + for (size_t i = 0; i != size; ++i)
> + entries[i] = value_type ();
>
> }
> m_n_deleted = 0;
> m_n_elements = 0;
alloc_entries uses mark_empty. untested:
Index: gcc/hash-table.h
===================================================================
--- gcc/hash-table.h (revision 249780)
+++ gcc/hash-table.h (working copy)
@@ -804,8 +804,8 @@ hash_table<Descriptor, Allocator>::empty
}
else
{
- for ( ; size; ++entries, --size)
- *entries = value_type ();
+ for (size_t i = 0; i < size; ++i)
+ mark_empty (entries[i]);
}
m_n_deleted = 0;
m_n_elements = 0;
