[Mirror] MueLu: Enable floating point exceptions in Automatic_Test_ETI

[csiefer2]

Automated mirror of upstream PR trilinos#14733 @trilinos/muelu

[github-actions]

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[gemini-code-assist]

Code Review

This pull request introduces a mechanism to enable floating-point exceptions (Divide-by-Zero, Overflow, and Invalid) for Linux and macOS platforms within the MueLu unit tests. The enableFPE function is added to the MueLu_Test namespace and invoked during test initialization. Feedback suggests marking the function as inline to prevent linker errors, fixing a state-tracking bug in the macOS implementation, and adopting a stateless approach for toggling exception bits.

[gemini-code-assist]

The enableFPE function has a few issues that should be addressed:

1. Multiple Definition Risk: Since the function is defined in a header file, it should be marked inline to prevent linker errors if the header is included in multiple translation units.
2. Logic Bug on Apple/SSE: The use of a static variable with an assignment (eMask = _MM_GET_EXCEPTION_MASK()) inside the if (enableFPE) block is problematic. If enableFPE(true) is called twice, the static variable will store the "enabled" state, causing a subsequent call to enableFPE(false) to fail to restore the original disabled state.
3. Stateless Implementation: It is cleaner and more robust to implement this in a stateless manner by toggling only the specific exception bits, which also makes the Apple implementation consistent with the Linux/glibc behavior.

inline void enableFPE(bool enableFPE) {
#if defined(__linux__) && defined(__GNUC__) && !defined(__INTEL_COMPILER)
  if (enableFPE) {
    feenableexcept(FE_DIVBYZERO | FE_OVERFLOW | FE_INVALID);
  } else {
    fedisableexcept(FE_DIVBYZERO | FE_OVERFLOW | FE_INVALID);
  }
#elif defined(__APPLE__) && defined(__GNUC__) && defined(__SSE__)
  if (enableFPE) {
    _MM_SET_EXCEPTION_MASK(_MM_GET_EXCEPTION_MASK() & ~(_MM_MASK_DIV_ZERO | _MM_MASK_OVERFLOW | _MM_MASK_INVALID));
  } else {
    _MM_SET_EXCEPTION_MASK(_MM_GET_EXCEPTION_MASK() | (_MM_MASK_DIV_ZERO | _MM_MASK_OVERFLOW | _MM_MASK_INVALID));
  }
#endif
}