yaxunl added a comment. In D75285#1897502 <https://reviews.llvm.org/D75285#1897502>, @jeroen.dobbelaere wrote:
> I don't think that 'restrict' is a good match for this behavior. For c++, the > alias_set proposal > (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4150.pdf) would be > a better match. > You would put the read access of *p in its own universe; or even better, > something like > > struct X { > int a; > char [[alias_set(MyOwnUniverseForX_b)]] b; > }; > > > Unfortunatly, there is no implementation yet. > > Imho, adding a '__attribute__((invariant))' or something similar (immutable ? > const_invariant ?) would be a better approach. (hmm, I like 'immutable') > > char test2(X *x) { > const char __attribute__((immutable)) *p = (const char > __attribute__((immutable))*)&(x->b); > // for all i: p[i] will never be modified. > return *p; > } > > > Extra precautions are probably needed to ensure that the initialization of > x->b is separated from the usage of it. Agree. An attribute like `__attribute__((immutable))` should be useful. It can be used on a pointer or reference and tells the compiler that the content of the pointer or reference is invariant in the scope of that variable. CHANGES SINCE LAST ACTION https://reviews.llvm.org/D75285/new/ https://reviews.llvm.org/D75285 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
