[llvm] r226075 - Fix PR22222

[Hans Wennborg]

On Thu, Jan 15, 2015 at 11:07 AM, Sanjoy Das
<sanjoy at playingwithpointers.com> wrote:
> Hi Hans,
>
> This should go into 3.6 only if r225282 is going into 3.6.

Yes, r225282 happened before the branch.

I've merged this fix in r226193.

Thanks,
Hans

> On Thu, Jan 15, 2015 at 10:28 AM, Hans Wennborg <hans at chromium.org> wrote:
>> Hi Sanjoy,
>>
>> On Wed, Jan 14, 2015 at 5:46 PM, Sanjoy Das
>> <sanjoy at playingwithpointers.com> wrote:
>>> Author: sanjoy
>>> Date: Wed Jan 14 19:46:09 2015
>>> New Revision: 226075
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=226075&view=rev
>>> Log:
>>> Fix PR22222
>>>
>>> The bug was introduced in r225282. r225282 assumed that sub X, Y is
>>> the same as add X, -Y. This is not correct if we are going to upgrade
>>> the sub to sub nuw. This change fixes the issue by making the
>>> optimization ignore sub instructions.
>>
>> Should we merge this to the 3.6 branch?
>>
>>  - Hans