[Bug tree-optimization/100958] New: two_value_replacement should move to match.pd

["pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100958

            Bug ID: 100958
           Summary: two_value_replacement should move to match.pd
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: tree-optimization
          Assignee: pinskia at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

two_value_replacement can be fully implemented in match.pd now.
So it should move.  I did not do it originally but it.

Comment from two_value_replacement :
/* Optimize
   # x_5 in range [cst1, cst2] where cst2 = cst1 + 1
   if (x_5 op cstN) # where op is == or != and N is 1 or 2
     goto bb3;
   else
     goto bb4;
   bb3:
   bb4:
   # r_6 = PHI<cst3(2), cst4(3)> # where cst3 == cst4 + 1 or cst4 == cst3 + 1

   to r_6 = x_5 + (min (cst3, cst4) - cst1) or
   r_6 = (min (cst3, cst4) + cst1) - x_5 depending on op, N and which
   of cst3 and cst4 is smaller.  */