[Bug tree-optimization/126265] New: If a and b in (CST, CST + 1), then .SPACESHIP (a, b, -1) is a - b

[kaelfandrew at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126265

            Bug ID: 126265
           Summary: If a and b in (CST, CST + 1), then .SPACESHIP (a, b,
                    -1) is a - b
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kaelfandrew at gmail dot com
  Target Milestone: ---

Created attachment 65045
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=65045&action=edit
C code

https://godbolt.org/z/83v1zqE6s
With -O3:

.SPACESHIP (a_7(D), b_8(D), -1)

should optimize to a - b if a and b in (CST, CST + 1).
This is similar to pr126227 cmp_int_asc_branchless ().