Code Reordering by visual c++compiler

When the same piece of c++ code is compiled with the same version of visual c++ compiler but at different times and possibly in different computers, does the code reordering performed by the compiler remains same or it may differ. i.e. does the logic behind code optimization by code reordering depend only on the code or it depends on various other paramete开发者_StackOverflowrs?

The context of the question is that I want to create a tool which finds out whether the two dlls are same or different based on their functionalities.

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Correct me if I'm wrong in assuming that since you want to compare dlls based on their functionality, you don't care about implementation details. Based on this assumption, it is clear that your tool could only look at the function signatures and classes, structs, etc definitions exposed by the dlls which would always be the same regardless of compiler for the same dll.