Re: [PATCH 1/3] Release structures on function return

["Jørgen Kvalsvik" <j@lambda.is>]

I think we need to revert this.

I got this email from linaro/gcc-regressions:

[Linaro-TCWG-CI] gcc-15-1649-g19f630e6ae8d: FAIL: 2 regressions on aarch64

regressions.sum:
		=== gcc tests ===

Running gcc:gcc.misc-tests/gcov.exp ...
FAIL: gcc.misc-tests/gcov-23.c (internal compiler error: in operator[], 
at vec.h:910)
FAIL: gcc.misc-tests/gcov-23.c (test for excess errors)

This did not reproduce on my machine, but I took a quick look at the 
hash-map implementation. hash_map.put calls 
hash_table.find_slot_with_hash, which calls hash_table.expand, which 
does move+destroy. auto_vec is not really move-aware which leads to a 
double-free.

The fix is either to make auto_vec move-aware (and more like C++'s 
std::vector) or revert this patch and apply the original version with an 
explicit release.

OK?

Thanks,
Jørgen

On 6/25/24 12:23, Jan Hubicka wrote:
>> The value vec objects are destroyed on exit, but release still needs to
>> be called explicitly.
>>
>> gcc/ChangeLog:
>>
>> 	* tree-profile.cc (find_conditions): Release vectors before
>> 	  return.
> I wonder if you turn
>      hash_map<int_hash<unsigned, 0>, vec<basic_block>> exprs;
> to
>      hash_map<int_hash<unsigned, 0>, auto_vec<basic_block>> exprs;
> Won't hash_map destructor take care of this by itself?
> 
> Honza
>> ---
>>   gcc/tree-profile.cc | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/gcc/tree-profile.cc b/gcc/tree-profile.cc
>> index e4bb689cef5..18f48e8d04e 100644
>> --- a/gcc/tree-profile.cc
>> +++ b/gcc/tree-profile.cc
>> @@ -919,6 +919,9 @@ find_conditions (struct function *fn)
>>       if (!have_post_dom)
>>   	free_dominance_info (fn, CDI_POST_DOMINATORS);
>>   
>> +    for (auto expr : exprs)
>> +      expr.second.release ();
>> +
>>       cov->m_masks.safe_grow_cleared (2 * cov->m_index.last ());
>>       const size_t length = cov_length (cov);
>>       for (size_t i = 0; i != length; i++)
>> -- 
>> 2.39.2
>>