C++17 std::launder and aliasing

Jakub Jelinek jakub@redhat.com
Fri Oct 21 16:43:00 GMT 2016


On Fri, Oct 21, 2016 at 05:29:25PM +0100, Jonathan Wakely wrote:
> >As said, nothing needed for the middle-end.
> 
> Thanks, Richi.
> 
> Moving from gcc@ to libstdc++@ as this is now libstdc++-specific.
> 
> So we can define std::launder as a no-op for GCC. LLVM apparently does
> have some optimizations that need to be disabled by doing the laundry,
> and Clang will be adding a T* __builtin_launder(T*) for that.

Or we could add a typegeneric __builtin_launder builtin that would
immediately fold to its argument.  Then we can change it any time we figure
out we need to do something there.

	Jakub



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