[Bug rtl-optimization/33796] valgrind error with -O2 for linux kernel code

["dcb314 at hotmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #6 from dcb314 at hotmail dot com  2007-10-18 17:33 -------
(In reply to comment #2)
> Although valgrind is correct that we are doing an uninitialized read, the code
> is actually working as designed and is correct.

I wish I had a pound for every time I've heard that ;->

> So yes we do some uninitialized accesses to the sparse array, but that's 
> ok.  

Sure ?

So absolutely *any* value is fine ?

Aren't there some machines where unaligned accesses to words fail ?

> It's also a benefit of sparseset, given that we don't
> have to memset/clear the whole sparseset data structure before using it, so
> it's fast.

I'd appreciate seeing some performance measurement numbers which 
tell us just how fast, so we can make a comparison of just how much
speed this tricky code is buying us.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33796