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[Bug rtl-optimization/33796] valgrind error with -O2 for linux kernel code
- From: "bergner at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 25 Oct 2007 18:46:23 -0000
- Subject: [Bug rtl-optimization/33796] valgrind error with -O2 for linux kernel code
- References: <bug-33796-9596@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #7 from bergner at gcc dot gnu dot org 2007-10-25 18:46 -------
>> So yes we do some uninitialized accesses to the sparse array, but that's
>> ok.
>
> So absolutely *any* value is fine ?
Yes, absolutely *any* value is fine. If you look at the code, you'll see that
the result of the uninitialized read is used to index into the dense array, but
only after guaranteeing that it is within bounds of the dense array.
Therefore, we're not just widely accessing random memory locations.
> Aren't there some machines where unaligned accesses to words fail ?
These are uninitialized reads, not unaligned reads.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33796