Erik <sigra@xxxxxxx> writes: > > This is not a bug. const on an automatic variable in C is more > > advisory than anything else. You are not permitted to change a const > > object, but you can cast its address to a non-const pointer. > It is a bug. If not in gcc, then in C, that allows the programmers to > do such strange things, preventing the compiler from optimizing the > code. The right thing for gcc to do would be to enable such > optimizations and warn when the code casts away constness, that it > could break optimized code. I believe that is what gcc already does > for some stupidities; gcc performs some optimizations that are broken > by reinterpret_cast and gives "warning: dereferencing type-punned > pointer will break strict-aliasing rules". So gcc should be modified > to be useful for users who need the optimization but not the bizarre > misfeatures of C. Those uses of reinterpret_cast are actually forbidden by the standard; that warning is telling you that you are doing something forbidden. The standard serves as a contract between the compiler and the programmer. There are reasons to sometimes modify the standard; it's not clear that this is one of them. > Anyway, it is surely a bug that gcc does not optimize away the "pushl > $77" inside the loop from the Ada program. Unlike C, Ada was not > designed for ugly hacks, but for clarity and for letting compilers > perform optimizations. So a promise is a promise. If a function says > it will not touch something, it won't. I don't know Ada. Ian
