-fno-strict-aliasing in CWARNFLAGS?

Dan Nicholson dbn.lists at gmail.com
Wed Feb 3 09:38:52 PST 2010

2010/2/3 Michel Dänzer <michel at daenzer.net>:
> On Wed, 2010-02-03 at 10:15 +0000, Colin Harrison wrote:
>> Michel Dänzer wrote:
>> > Traditionally, -fno-strict-aliasing was definitely necessary for the X
>> > server and/or some drivers to work correctly.
>> Strict aliasing used to be a can'o worms...
>> http://lkml.org/lkml/2003/2/26/158
>> and last time I tried strict aliasing for Xming (many moons ago) I fell flat
>> on my face.
>> But is series 4 gcc now much better?
> Problems with strict aliasing are usually due to strict aliasing
> violations in the code being compiled, not bugs in the compiler. So
> newer compilers can't really help (in fact the opposite may be true, as
> I think newer versions of gcc tend to obey strict aliasing even more
> strictly), the only help would be fixing the code bugs. I'm sure some of
> them have been fixed...

Here's an example of newer gcc changing behavior with strict aliasing
that I just happened to see the other day.



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