[PATCH] Fix PR52614

[Richard Guenther]

On Thu, Apr 5, 2012 at 1:59 PM, William J. Schmidt
<wschmidt@linux.vnet.ibm.com> wrote:
> On Thu, 2012-04-05 at 11:30 +0200, Richard Guenther wrote:
>> On Thu, Apr 5, 2012 at 6:22 AM, Mike Stump <mikestump@comcast.net> wrote:
>> > On Apr 4, 2012, at 7:56 PM, William J. Schmidt wrote:
>> >> There seems to be tacit agreement that the vector tests should use
>> >> -fno-common on all targets to avoid the recent spate of failures (see
>> >> discussion in 52571 and 52603).
>> >
>> >> OK for trunk?
>> >
>> > Ok.  Any other solution I think will be real work and we shouldn't loose the testing between now and then by not having the test cases working.
>>
>> Ian, you are the "source" of all of these problems.  While I did not notice
>> any degradations in SPEC (on x86) with handling commons "correctly"
>> now, the fact
>> that our testsuite needs -fno-common to make things vectorizable shows
>> that users might be impacted negatively by this, which is only a real problem
>> in corner cases.  Why can the link editor not promote the definitions alignment
>> when merging with a common with bigger alignment?
>>
>> Richard.
>>
>
> Follow-up question:  Should -ftree-vectorize imply -fno-common in the
> short term?

That's probably more a C language question - you would get valid C
rejected with -fno-common.  But maybe -ftree-vectorize should suggest
-fno-common when it encounters a case it would like to promote alignment
for.  Not sure if for example Fortran would ever work with -fno-common though.

Richard.

> Thanks,
> Bill
>