Messages in this thread | | | Subject | Re: Linux 2.6.7-rc2 | From | Albert Cahalan <> | Date | 31 May 2004 11:12:26 -0400 |
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On Mon, 2004-05-31 at 12:53, Linus Torvalds wrote: > On Mon, 31 May 2004, Albert Cahalan wrote: > > > > This would be required because of the -Wno-strict-aliasing > > option. For the 2.7.xx kernels, how about we start off by > > replacing -Wno-strict-aliasing with -std=gnu99 ? It's been > > 5 years since 1999. The "restrict" keyword is useful too. > > No can do. > > Aliasing in gcc is so broken (_purely_ type-based and no way to avoid it > sanely in older versions) that it's not going to happen. > > When we can depend on everybody having gcc-3.3+ something, and that one > properly supports the "may_alias" attribute, we may change that.
By the time Linux 2.8.0 is out, gcc-3.3+ should be a perfectly reasonable requirement.
In the mean time, adding may_alias as needed would be a good idea.
If all this were behind CONFIG_BROKEN, it sure wouldn't hurt even today. People might as well get started. The compiler will keep being pessimistic and dumb until the -Wno-strict-aliasing option is dropped.
> "restrict" is pretty much useless. It just weakens the already too-weak > alias rules of standard gcc.
It's easiest to use on function parameters. This helps the optimizer without being a mind-warping excercise.
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