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Date: Thu, 23 Jul 2015 13:36:00 -0000
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Subject: Re: [PR25529] Convert (unsigned t * 2)/2 into unsigned (t & 0x7FFFFFFF)
From: Richard Biener <richard.guenther@gmail.com>
To: "Hurugalawadi, Naveen" <Naveen.Hurugalawadi@caviumnetworks.com>
Cc: "marc.glisse@inria.fr" <marc.glisse@inria.fr>, GCC Patches <gcc-patches@gcc.gnu.org>
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On Thu, Jul 23, 2015 at 5:47 AM, Hurugalawadi, Naveen
<Naveen.Hurugalawadi@caviumnetworks.com> wrote:
>>> so using wi::mask is prefered here.
>
> Thanks for your review and comments.
>
> Please find attached the modified patch as per your comments.
>
> Please let me know if this version is okay?

Ok with adding

/* { dg-require-effective-target int32 } */

to the testcase.

Please omit the

+/* Simplify (t * 2)/2 ->  t.  */
+(simplify
+ (exact_div (mult @0 INTEGER_CST@1) @1)
+ (if (TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)))
+  @0))

pattern.  As a followup extend it - it shoudl also work for non-INTEGER_CST
divisors and it should work for any kind of division, not just exact_div.  The
key here is TYPE_OVERFLOW_UNDEFINED.  I believe you should
find the equivalent operation in extract_trunc_div_1.

Richard.

> Thanks,
> Naveen
>
> 2015-07-22  Naveen H.S  <Naveen.Hurugalawadi@caviumnetworks.com>
>
> gcc/testsuite/ChangeLog:
>          PR middle-end/25529
>          * gcc.dg/pr25529.c: New test.
>
> gcc/ChangeLog:
>          PR middle-end/25529
>          * match.pd (exact_div (mult @0 INTEGER_CST@1) @1) :     New simplifier.
>          (trunc_div (mult @0 integer_pow2p@1) @1) : New simplifier.