Re: [PATCH] Fix PR 33512 Folding of x & ((~x) | y) into x & y on the tree level

[Andrew Pinski <andrew dot pinski at caviumnetworks dot com>]

This time with the patch and describing what the bug was.  The problem
was defcodefor_name does not always set arg1 and arg2.  This fixes it
so it is always set to NULL if they don't exist.

Thanks,
Andrew

On Fri, Apr 20, 2012 at 9:05 PM, Andrew Pinski
<andrew.pinski@caviumnetworks.com> wrote:
> On Thu, Jan 19, 2012 at 3:13 AM, Richard Guenther
> <richard.guenther@gmail.com> wrote:
>> On Thu, Jan 19, 2012 at 10:00 AM, Andrew Pinski
>> <andrew.pinski@caviumnetworks.com> wrote:
>>> On Tue, Jan 17, 2012 at 1:38 AM, Richard Guenther
>>> <richard.guenther@gmail.com> wrote:
>>>> On Tue, Jan 17, 2012 at 8:06 AM, Andrew Pinski
>>>> <andrew.pinski@caviumnetworks.com> wrote:
>>>>> Hi,
>>>>> ÂThis adds the folding of x & ((~x) | y)) into x & y on the tree
>>>>> level via fold-const.c
>>>>> There is already partly done on the RTL level but it would be a good
>>>>> thing for the tree level also.
>>>>>
>>>>>
>>>>> OK for 4.8 (yes I know we have not branched yet but I thought I would
>>>>> send it out so I don't forget about it)?
>>>>> Bootstrapped and tested on x86_64-linux-gnu with no regressions.
>>>>
>>>> Can you instead patch tree-ssa-forwprop.c:simplify_bitwise_binary?
>>>
>>> Yes and here is a new patch which also adds optimizing x | ((~x) & y)) to x | y.
>>> Also it adds the optimizing x & (x | y) to x and x | (x & y) to x to
>>> tree-ssa-forwprop.c:simplify_bitwise_binary
>>> since it was an easy extension on top of the ~x case (well I
>>> implemented the one without the ~ first). ÂI did not remove those
>>> folding from fold-const.c though.
>>>
>>> Also I was thinking maybe this belongs in reassociate though I don't
>>> see how to do it.
>>
>> I still have plans to create that piecewise gimple_fold (see my proposal
>> from early last year) that would be the container for this kind of pattern
>> matching. ÂIt would then be usable from reassoc as well (but reassoc
>> has the issue of only collecting one kind of op, so its simplification
>> wouldn't trigger reliably on these).
>>
>> http://gcc.gnu.org/ml/gcc-patches/2011-03/msg01099.html
>>
>>> OK for 4.8, once in stage 1? Again bootstrapped and tested on
>>> x86_64-linux-gnu with no regressions.
>>
>> Ok.
>
> Here is an updated patch which fixes a bug which I found while doing
> the treecombine branch. ÂI rewrote defcodefor_name so more than
> SSA_NAMEs can be passed to it.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
>
> Thanks,
> Andrew Pinski
>
> ChangeLog:
>
> ChangeLog:
> * tree-ssa-forwprop.c (defcodefor_name): New function.
> (simplify_bitwise_binary): Use defcodefor_name instead of manually
> Simplify "( X | Y) & X" to X and "( X & Y) | X" to X.
> Simplify "(~X | Y) & X" to "X & Y" and
> "(~X & Y) | X" to "X | Y".
>
> testsuite/ChangeLog:
> * gcc.dg/tree-ssa/andor-3.c: New testcase.
> * gcc.dg/tree-ssa/andor-4.c: New testcase.
> * gcc.dg/tree-ssa/andor-5.c: New testcase.
>
>>
>> Thanks,
>> Richard.
>>
>>> Thanks,
>>> Andrew Pinski
>>>
>>> ChangeLog:
>>> * tree-ssa-forwprop.c (defcodefor_name): New function.
>>> (simplify_bitwise_binary): Use defcodefor_name.
>>> Simplify "( X | Y) & X" to X and "( X & Y) | X" to X.
>>> Simplify "(~X | Y) & X" to "X & Y" and
>>> "(~X & Y) | X" to "X | Y".
>>>
>>> testsuite/ChangeLog:
>>> * gcc.dg/tree-ssa/andor-3.c: New testcase.
>>> * gcc.dg/tree-ssa/andor-4.c: New testcase.
>>> * gcc.dg/tree-ssa/andor-5.c: New testcase.
>>>
>>>
>>>>
>>>> Thanks,
>>>> Richard.
>>>>
>>>>> Thanks,
>>>>> Andrew Pinski
>>>>>
>>>>> ChangeLog:
>>>>> * fold-const.c (fold_binary_loc <case BIT_AND_EXPR>): Add folding of x
>>>>> & (~x | y) into x & y.
>>>>>
>>>>> testsuite/ChangeLog:
>>>>> * gcc.dg/tree-ssa/andor-3.c: New testcase.

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