GCC recommendations and options for fastest code

Question

I\'m distributing a C++ program with a makefile for the Unix version, and I\'m wondering what compiler options I should use to get the fastest possible code (it falls into t

Answer 1

There is no 'fastcall' on x86-64 - both Win64 and Linux ABI define register-based calling ("fastcall") as the only calling convention (though Linux uses more registers).