Re: [PR25529] Convert (unsigned t * 2)/2 into unsigned (t & 0x7FFFFFFF)

[Hurugalawadi, Naveen]

Hi,  

>> extend it - it should also work for non-INTEGER_CST
>> divisors and it should work for any kind of division, not just exact_div.  

Please find attached the patch "pr25529.patch" that implements the pattern
for all divisors

Please review and let me know if its okay.  

Regression tested on AARH64 and x86_64.

Thanks,
Naveen  

2015-08-07  Naveen H.S  <naveen.hurugalaw...@caviumnetworks.com>

PR middle-end/25529 

        gcc/ChangeLog:  
        * match.pd (div (mult @0 @1) @1) : New simplifier.


diff --git a/gcc/match.pd b/gcc/match.pd
index 4230f9a..18045b8 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -296,6 +296,13 @@ along with GCC; see the file COPYING3.  If not see
  (if (TYPE_UNSIGNED (TREE_TYPE (@0)))
   (bit_and @0 (negate @1))))
 
+/* Simplify (t * 2) / 2) -> t.  */
+(for div (trunc_div ceil_div floor_div round_div exact_div)
+ (simplify
+  (div (mult @0 @1) @1)
+  (if (TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)))
+   @0)))
+
 /* X % Y is smaller than Y.  */
 (for cmp (lt ge)
  (simplify