identical assembly. No C++ compiler that I'm aware of does that.
e.g., std::vector<Foo * > and std::vector<Bar * > generate identical code for whatever you do, as they both only deal with the pointer, never dereference it in any way. Also, in code like
template <class T> T get(T x[], int i) { return x[i]; }
on a 32 bit platform, get<int>() and get<char* > generate the same machine code, whereas on a 64 bit platform, get<long>() and get<void * >() generate the same machine code.
No C++ compiler that I'm aware of folds these cases into one; The C# generics do (not sure about non-generic code with identical final machine code). I would be surprised if idiomatic C++ code could be shortened by more than 50% by a compiler that did. However, if you write your code for column-major access, the binary can go down 90% if the compiler did that.
The C++ committee answer to this is to use "partial template specialization". I'm hoping all the standard libraries I use such as Boost etc have already done this to avoid code bloat.
But I agree that it would be nice if the compiler did this automatically.
e.g., std::vector<Foo * > and std::vector<Bar * > generate identical code for whatever you do, as they both only deal with the pointer, never dereference it in any way. Also, in code like
on a 32 bit platform, get<int>() and get<char* > generate the same machine code, whereas on a 64 bit platform, get<long>() and get<void * >() generate the same machine code.No C++ compiler that I'm aware of folds these cases into one; The C# generics do (not sure about non-generic code with identical final machine code). I would be surprised if idiomatic C++ code could be shortened by more than 50% by a compiler that did. However, if you write your code for column-major access, the binary can go down 90% if the compiler did that.
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