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I want to assure you that the compiler does not exclusively use the ISO language standard to define the behavior of internal components of the implementation.

• Dylan16807 10y ago
  I'm talking about a specific component named memcpy. Obviously this does not apply to other components. And even that is only if the bug report is correct.
  • chandlerc1024 10y ago
    The compiler is not producing C code that calls memcpy. It is leveraging a specific implementation of a memcpy symbol in a particular system library. The contract between Clang and that system library can include guarantees not provided by any ISO standard.
    • Dylan16807 10y ago
      Then the bug report is wrong, and disregard the second and third posts I made. They depend on the bug report not being wrong. My first post is generic and not about this particular issue; it's still fine.
      • whitequark_ 10y ago
        The bug report is not wrong. Rather, whether the current behavior is correct depends on the platform. For example, Darwin's libc offers this contract for memcpy and clang is perfectly within its rights to generate such code (note that the IR it generates is still violating LLVM's contract on the memcpy intrinsic); glibc offers no such contract for memcpy, and so clang's code is nonconformant.