[PATCH] bring -Warray-bounds closer to -Wstringop-overflow (PR91647, 91463, 91679)

[Martin Sebor]

On 12/9/19 9:11 AM, Matthew Malcomson wrote:
> On 01/11/2019 21:09, Martin Sebor wrote:
>> diff --git a/gcc/gimple-match-head.c b/gcc/gimple-match-head.c
>> index 53278168a59..d7c74a1865a 100644
>> --- a/gcc/gimple-match-head.c
>> +++ b/gcc/gimple-match-head.c
>> @@ -837,8 +837,8 @@ try_conditional_simplification (internal_fn ifn, gimple_match_op *res_op,
>>      gimple_match_op cond_op (gimple_match_cond (res_op->ops[0],
>>    					      res_op->ops[num_ops - 1]),
>>    			   op, res_op->type, num_ops - 2);
>> -  for (unsigned int i = 1; i < num_ops - 1; ++i)
>> -    cond_op.ops[i - 1] = res_op->ops[i];
>> +
>> +  memcpy (cond_op.ops, res_op->ops + 1, (num_ops - 1) * sizeof *cond_op.ops);
>>      switch (num_ops - 2)
>>        {
>>        case 2:
> 
> I think this copies one extra element than the original code.
> 
> (copying `num_ops - 1` elements, while the previous loop only copied
> `num_ops - 2` elements since the counter started at 1).
> 

Yes, I think you're right.  I only noticed after I committed
the change, but didn't think it actually causes any problems
(i.e., it doesn't read past the end).  Let me know if you
think otherwise.

Martin