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An execution boundary is the delimitation between code compiled by differing compilers, including different versions of a compiler produced by the same vendor. For instance, a function may be declared in a header file but defined in a library that is loaded at runtime. The execution boundary exists between the call site in the executable and the function implementation in the library. Such boundaries are also called ABI (application binary interface) boundaries because they relate to the interoperability of application binaries.
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