------- Comment From [email protected] 2015-10-01 01:46 EDT-------
Assuming the upstream GCC 5 code was used, as I'm sure it was, the patches were 
definitely present.

I think the problem is that Ubuntu is still being built with
-mcpu=power7 -mtune=power8.  That will cause the alignment optimization
to be missed; since unaligned loads perform poorly on Power7, gcc favors
the realignment code that confuses valgrind.

My understanding is that Ubuntu 16.04 will move to using -mcpu=power8,
at which point this should no longer be an issue.

So unfortunately I believe we need to carry over the -O3 -fno-tree-
vectorize workaround for shared/vg_replace_strmem.c in 15.10.  This
workaround can then be removed for 16.04.

Matthias, could you please change the build rules to implement the
circumvention?

Thanks!

Bill

-- 
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/1434222

Title:
  Spurious valgrind errors due to memcpy replacement getting
  autovectorised

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/valgrind/+bug/1434222/+subscriptions

-- 
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs

Reply via email to