[Bug middle-end/55027] simplify vector multiplication by 1

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55027



Richard Biener <rguenth at gcc dot gnu.org> changed:



           What    |Removed                     |Added

----------------------------------------------------------------------------

             Status|UNCONFIRMED                 |NEW

           Keywords|                            |missed-optimization

   Last reconfirmed|                            |2012-10-23

                 CC|                            |rguenth at gcc dot gnu.org

     Ever Confirmed|0                           |1

           Severity|normal                      |enhancement



--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> 2012-10-23 
09:41:54 UTC ---

For integer values the generic folding with



      if (! FLOAT_TYPE_P (type))

        {

          if (integer_zerop (arg1))

            return omit_one_operand_loc (loc, type, arg1, arg0);

          if (integer_onep (arg1))

            return non_lvalue_loc (loc, fold_convert_loc (loc, type, arg0));



catches this.  For float values we have



          /* Maybe fold x * 0 to 0.  The expressions aren't the same

             when x is NaN, since x * 0 is also NaN.  Nor are they the

             same in modes with signed zeros, since multiplying a

             negative value by 0 gives -0, not +0.  */

          if (!HONOR_NANS (TYPE_MODE (TREE_TYPE (arg0)))

              && !HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg0)))

              && real_zerop (arg1))

            return omit_one_operand_loc (loc, type, arg1, arg0);

          /* In IEEE floating point, x*1 is not equivalent to x for snans.

             Likewise for complex arithmetic with signed zeros.  */

          if (!HONOR_SNANS (TYPE_MODE (TREE_TYPE (arg0)))

              && (!HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg0)))

                  || !COMPLEX_FLOAT_TYPE_P (TREE_TYPE (arg0)))

              && real_onep (arg1))

            return non_lvalue_loc (loc, fold_convert_loc (loc, type, arg0));



but neiter real_zerop or real_onep handle vector types (there are more

predicates like that).  I adjusted the integer predicates to also handle

vector types, so I suppose the same needs to be done for the real predicates.