[Bug tree-optimization/56933] [4.9 Regression] Vectorizer missing read-write dependency for interleaved accesses

["bernd.edlinger at hotmail dot de" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56933

--- Comment #6 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
(In reply to Jakub Jelinek from comment #5)
> (In reply to Bernd Edlinger from comment #4)
> The test case
> gcc.dg/vect/pr56933.c fails on a pentium II,
> because of invalid
> instruction.
> 
> A fairly obvious fix (which works for me) would be:

There
> is nothing obvious on it (maybe obviously broken).
The vect.exp tests aren't
> i?86/x86_64 only, so you definitely can't add
unguarded requirements for
> specific CPUs, it would cause the test not to be run on ppcs/arm/etc.

The
> bug in this test is that it specifies { dg-do run }, either it shouldn't
> (then the default will be run if CPU supports the -msse2 flags in this case,
> or
compile otherwise), or it should use the tree-vect.h + check_vect ()
> framework like many other tests.

Oh I thought that it is only for x86...

The problem is that the option -msse2 is somehow used to compile this
and therfore the following statement is generated.

       movapd  .LC4, %xmm0

I do not see how this test case can test anything unless it scans
the assembler output for this instruction. Maybe there is something
special in the -fdump-tree-xxx that should be looked for?