-AA -D_HP_NONSTD_FAST_IOSTREAM Performance Improvement Macro

A new performance improvement preprocessor macro, _HP_NONSTD_FAST_IOSTREAM can be used to improve -AA iostream performance.

This macro enables the following non-standard features:

Sets std::ios_base::sync_with_stdio(false), which disables the default synchronization with stdio.
Sets std::cin.tie(0), which unties the cin from other streams.
Replaces all occurrences of "std::endl" with "\n".

Enabling this macro might result in noticeable performance improvement if the application uses iostreams often.




	NOTE: Do not enable the macro in any of the following cases: If the application assumes a C++ stream to be in sync with a C stream. If the application depends on stream flushing behavior with endl. If the user uses "std::cout.unsetf(ios::unitbuf)" to unit buffer the output stream.

Technical documentation