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copied!<p>Even if there was a way to get the sizeof() a function, it may still fail when you try to call a version that has been copied to another area in memory. What if the compiler has local or long jumps to specific memory locations. You can't just move a function in memory and expect it to run. The OS can do that but it has all the information it takes to do it.</p> <hr> <p>I was going to ask how operating systems do this but, now that I think of it, when the OS moves stuff around it usually moves a whole page and handles memory such that addresses translate to a page/offset. I'm not sure even the OS ever moves a single function around in memory. </p> <hr> <p>Even in the case of the OS moving a function around in memory, the function itself must be declared or otherwise compiled/assembled to permit such action, usually through a pragma that indicates the code is relocatable. All the memory references need to be relative to its own stack frame (aka local variables) or include some sort of segment+offset structure such that the CPU, either directly or at the behest of the OS, can pick the appropriate segment value. If there was a linker involved in creating the app, the app may have to be re-linked to account for the new function address. </p> <p>There are operating systems which can give each application its own 32-bit address space but it applies to the entire process and any child threads, not to an individual function. </p> <p>As mentioned elsewhere, you really need a language where functions are first class objects, otherwise you're out of luck.</p>

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