This is the mail archive of the mailing list for the GCC project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

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

On Tue, Jan 17, 2012 at 1:38 AM, Richard Guenther
<> wrote:
> On Tue, Jan 17, 2012 at 8:06 AM, Andrew Pinski
> <> 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
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.

OK for 4.8, once in stage 1? Again bootstrapped and tested on
x86_64-linux-gnu with no regressions.

Andrew Pinski

* 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".

* 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.

Attachment: addmoreandorforw.diff.txt
Description: Text document

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]