[Bug target/115982] ICE: unrecognizable insn in ira_remove_insn_scratches with -mavx512vl

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115982

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|ra                          |
          Component|rtl-optimization            |target

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
IRA is the first pass after split1 that runs recog on the instructions. So that
is why ira is mentioned.

split1 splits:
```
(insn 17 13 18 2 (set (reg/i:V4SI 20 xmm0)
        (vec_merge:V4SI (const_vector:V4SI [
                    (const_int -1 [0xffffffffffffffff]) repeated x4
                ])
            (const_vector:V4SI [
                    (const_int 0 [0]) repeated x4
                ])
            (unspec:QI [
                    (reg:V4SF 106)
                    (reg:V4SF 102)
                    (const_int 0 [0])
                ] UNSPEC_PCMP))) "/app/example.cpp":20:1 2929 {*avx_cmpv4sf3_1}
     (expr_list:REG_DEAD (reg:V4SF 102)
        (expr_list:REG_DEAD (reg:V4SF 106)
            (nil))))
```

into:
```
(insn 23 13 24 2 (set (reg:V4SF 107)
        (unspec:V4SF [
                (reg:V4SF 106)
                (reg:V4SF 102)
                (const_int 0 [0])
            ] UNSPEC_PCMP)) "/app/example.cpp":20:1 -1
     (nil))
(insn 24 23 18 2 (set (reg/i:V4SI 20 xmm0)
        (subreg:V4SI (reg:V4SF 107) 0)) "/app/example.cpp":20:1 -1
     (nil))
```