[Bug rtl-optimization/87701] [9 Regression] ICE in elimination_costs_in_insn, at reload1.c:3640 since r265398

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87701

Segher Boessenkool <segher at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |segher at gcc dot gnu.org

--- Comment #6 from Segher Boessenkool <segher at gcc dot gnu.org> ---
We start off with

(insn 36 35 9 2 (set (reg:V4SI 104)
        (subreg:V4SI (reg:TI 1 dx [ b ]) 0)) "87701.cc":13:31 -1
     (expr_list:REG_DEAD (reg:DI 2 cx)
        (expr_list:REG_DEAD (reg:DI 1 dx)
            (nil))))

and replace that with

(insn 41 35 42 2 (set (reg:V4SI 107)
        (reg:TI 1 dx [ b ])) "87701.cc":13:31 -1
     (expr_list:REG_DEAD (reg:TI 1 dx [ b ])
        (nil)))


    42: r104:V4SI=r107:V4SI
      REG_DEAD r107:V4SI

(no long form dump for that last one, sorry).  Note the subreg has
gone missing.  So which is correct here: with or without subreg?