That's an interesting note. I wonder why they claim this. As far as I know, `[[gnu::optimize("-fno-tree-loop-distribute-patterns")]]` (or the equivalent #pragma) is required for implementing a memcpy function in C unless you do something funky with the build system.
Because these optimizations are not supposed to be a part of the user interface. They're internal passes and may one day go away or be merged or subsumed etc.
My guess is that the attribute interacts weirdly with optimizations spanning function calls, like inlining. It might be safe for TUs that define a single function, like with memmove above. Having said that applying the option to the TU itself would be equivalent, and not discouraged by GCC docs.
