>> I still haven't seen any measurements showing any benefits from making >> this change. Are there any? > > I think Michael is asking a very good question here. The strict > aliasing rules introduced in C99 have always been somewhat > controversial. They get in the way for lots of low-level programming > tasks such as protocol decoding and frame buffer manipulations. And > at least in my opinion the rules are simply hard to understand; I need > to read up on the issue again every time it pops up. > > I may be somewhat overcautious, but I would keep -fno-strict-aliasing > as a default. And I'd only enable -fstrict-aliasing for particular > bits of code where it has a significant performance benefit, and > people have done a careful analysis of the code to see if it is free > of aliasing issues.
The point I'm trying to make here is that: 1) It is *NOT* a warning flag. Using CWARNFLAGS should *only* enable warnings, not change the resulting assembly. 2) It was never intended to be in all of the modules. It landed there by accident when the code was copy/pasted from one configure.ac to another and then into util-macros. 3) Performance gains are not in consideration here. _______________________________________________ [email protected]: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: http://lists.x.org/mailman/listinfo/xorg-devel
