[Bug tree-optimization/119945] New: [14/15/16 Regression] missed tail call due to IPA-VRP and different type but same mode

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119945

            Bug ID: 119945
           Summary: [14/15/16 Regression] missed tail call due to IPA-VRP
                    and different type but same mode
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Created attachment 61198
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=61198&action=edit
testcase

Take the attached testcase. Starting in GCC 14, GCC won't tail call f inside g.
But f1 is handled inside g1 just fine still.

This is because the useless_type_conversion_p check inside find_tail_calls is
stronger than what is included for process_assignment .