[cfe-dev] Even more clang ideas
Ted Kremenek
kremenek at apple.com
Sat Jul 26 10:34:53 PDT 2008
On Jul 25, 2008, at 10:09 PM, Chris Lattner wrote:
>>
>> Interesting. I think this illustrates my point that the strict
>> aliasing rules in C99 don't really apply to Objective-C, at least in
>> the implementation provided by GCC. This is clearly a deliberate
>> choice, likely to avoid the issues you mentioned.
>
> -fstrict-aliasing being off by default has more to do with its
> implementation in GCC than it does the objc type system. I don't
> think that any of the things John is talking about affect -fstrict-
> aliasing.
>
> When llvm-gcc (and eventually clang) supports type based alias
> analysis, it will almost certainly be on by default, even on the mac.
Cool. In that case, will strict-aliasing support for Objective-C take
into consideration the subtyping relationships in Objective-C? The
original point with regards to strict-aliasing really concerns whether
or not C99 strict-aliasing rules apply verbatim to pointers to
Objective-C objects.
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