On Fri, Jan 15, 2016 at 04:26:36PM +0100, SF Markus Elfring wrote: > >> Would you like to clarify any measurable effects around the implementation > >> detail when various variables will only be initialised immediately > >> before they will be read again? > > > > Compiler will drop this variable initialization by itself because > > there are no reads between this variable initialization and write. > > Which compiler variants would you to take into account for such an use case? GCC supported it before 1999 when I saw it first time. My assumption that in 2016 all compilers are doing such optimization now. I would be glad to hear an example of modern compiler which doesn't support this simple optimization. > > > > I recommend you to take a look on the assembly code and ensure it > > by yourself. > > Will any configuration parameters and command arguments become relevant > to improve also a corresponding software comparison? Please suggest us, you are proposing this change, and not me. > > > > The proposed change won't affect performance at all. > > Will unneeded variable assignments be really optimised away by default? Yes > > > By the way: > Will a small source code reduction matter also a bit here? If you are interested in saving space of one latter, you need to take into account git database increase, do you? > > Regards, > Markus -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
