[PATCH PR69052]Set higher precedence for CONST_WIDE_INT than CONST_INT when canonicalizing addr expr

[Richard Biener]

On March 4, 2016 5:35:13 PM GMT+01:00, "Bin.Cheng" <amker.cheng@gmail.com> wrote:
>On Fri, Mar 4, 2016 at 11:57 AM, Richard Biener
><richard.guenther@gmail.com> wrote:
>> On Fri, Mar 4, 2016 at 12:07 PM, Bin Cheng <Bin.Cheng@arm.com> wrote:
>>> Hi,
>>> A address canonicalization interface was introduced by my original
>patch to PR69052.  The interface sorts sub-parts in an address
>expression based on precedences defined by function
>commutative_operand_precedence.  It also assumes that all CONST_INT
>sub-parts are at the end of vector after sorting.  But this is not
>always true because commutative_operand_precedence sets the same
>precedence to both CONST_INT and CONST_WIDE_INT.  The patch could be
>broken in cases which have CONST_WIDE_INT sorted after CONST_INT.  Even
>though I don't think we can really run into such complicated case, I
>worked out a patch forcing CONST_INT to lower precedence than
>CONST_WIDE_INT, so that for sure it will be sorted after all other
>kinds sub-parts.
>>>
>>> This is an obvious change.  Bootstrap&test on x86_64, bootstrap&test
>on AArch64.  Is it OK for this stage?
>>
>> I believe the obvious change would be to change
>> commutative_operand_precedence to pre-CONST_WIDE_INT behavior, namely
>> giving CONST_WIDE_INT the same precedence as CONST_DOUBLE.
>Yes, but I am not sure what else this change will affect, so I made
>the smallest change in the original code.

I don't like going with this kind of weirdo changes out of caution.  If you think it's too dangerous the push it back to gcc 7 and consider backporting for 6.2

  I am testing this now.  It
>would be great if anyone describes it a bit.

Thanks,
Richard.

>
>Thanks,
>bin
>>
>> Richard.
>>
>>
>>
>>> Thanks,
>>> bin
>>>
>>> 2016-03-04  Bin Cheng  <bin.cheng@arm.com>
>>>
>>>         PR rtl-optimization/69052
>>>         * loop-invariant.c (compare_address_parts): Force CONST_INT
>to lower
>>>         precedence than CONST_WIDE_INT.