> Mark Mitchell writes:
>> Kazu Hirata wrote:
>> ...
>> static const int array[] = { 0, 0, 0, 1, 1, 1, 2, 2, 2 };
>>
>> int
>> foo (int a)
>> {
>> return array[7];
>> }
>>
>> I am trying to fold array[7] into 2. It turns out that if T is an
>> ARRAY_REF,
>>
>> TREE_READONLY (TREE_OPERAND (T, 0))
>>
>> is 0. Why? This would be 1 if the program is fed into the C front
>> end, which is needed to safely fold a constant array reference.
>
> That's a bug, or, rather, a place where the C++ front-end is failing to give
> full information to the optimizer. It should be TREE_READONLY. There are some
> tricky bits, in that if we're doing a dynamic initialization, we presently
> cannot mark it TREE_READONLY, but this is a static initialization, so it
> should be fine. Isn't TREE_OPERAND (T, 0) the VAR_DECL for array itself? If
> so, waht's probably going wrong is that it's not being marked TREE_READONLY
> because we're afraid of the dynamic initialization case. We're missing a call
> to c_apply_quals_to_decl (sp?) somewhere.
- ??? no such thing, you can't "dynamically" initialize a "static const",
as then it's not a "static const", but rather simply a global "const"
(as a "static const" object is logically equivalent to a named/addressable
literal, yes?)
