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

[Richard Guenther <richard dot guenther at gmail dot com>]

On Sat, Apr 21, 2012 at 6:06 AM, Andrew Pinski
<andrew.pinski@caviumnetworks.com> wrote:
> 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.

Ok with ...

+  if (code1 == SSA_NAME)
+    {
+      def = SSA_NAME_DEF_STMT (name);
+
+      if (def && is_gimple_assign (def)
+	  && can_propagate_from (def))
+	{
+	  code1 = gimple_assign_rhs_code (def);
+	  arg11 = gimple_assign_rhs1 (def);
+          arg21 = gimple_assign_rhs2 (def);
+          arg31 = gimple_assign_rhs2 (def);
+	}
+    }

... recursing here instead.

Thanks,
Richard.


> 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,
>>>>>> ?This 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). ?I 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. ?It 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. ?I 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.