What are the key considerations in linking object modules?

The key considerations in linking object modules include symbol resolution, relocation, and the handling of libraries.

Symbol resolution is a crucial aspect of linking object modules. This process involves resolving the references to symbols that are not defined in the current module. The linker must ensure that for every symbol referenced in the object module, there is a corresponding definition in another module or in a library. If the linker cannot find a definition for a referenced symbol, it will generate an error. This is because the absence of a definition means that the final executable will not know what to do when it encounters that symbol during execution.

Relocation is another important consideration. The linker must adjust the addresses of symbols and references to those symbols in the object module, so that they point to the correct locations in the final executable. This process is necessary because the addresses in the object module are based on an assumption that the module will be loaded at a certain location in memory, which may not be the case in the final executable. The linker must therefore adjust these addresses to reflect the actual load location of the module in the executable.

Handling libraries is also a key consideration in linking object modules. Libraries are collections of object modules that provide commonly used functions and procedures. The linker must search these libraries to find definitions for symbols that are not defined in the object modules being linked. However, the linker must be careful not to include unnecessary code from the libraries in the final executable. This is because including unnecessary code would increase the size of the executable and potentially slow down its execution. Therefore, the linker must only include the parts of the library that are actually used by the object modules.

In conclusion, linking object modules is a complex process that involves several key considerations. The linker must resolve symbols, relocate addresses, and handle libraries effectively to produce a correct and efficient executable.