[Bug rtl-optimization/114190] wrong code with -O2 -fno-dce -fharden-compares -mvpclmulqdq --param=max-rtl-if-conversion-unpredictable-cost=136

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114190

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2024-03-01
          Component|target                      |rtl-optimization

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
cmpelim produces:
```
(insn 22 21 486 2 (set (reg:CCZ 17 flags)
        (compare:CCZ (reg:SI 4 si [orig:111 _21+4 ] [111])
            (const_int 0 [0]))) "/app/example.cpp":8:8 discrim 1 7
{*cmpsi_ccno_1}
     (expr_list:REG_UNUSED (reg:CCZ 17 flags)
        (nil)))
(insn 486 22 466 2 (set (reg:DI 1 dx [353])
        (plus:DI (reg/f:DI 7 sp)
            (const_int 212 [0xd4]))) "/app/example.cpp":8:65 discrim 1 254
{*leadi}
     (nil))
(insn 466 486 383 2 (set (reg:DI 4 si [354])
        (const:DI (plus:DI (symbol_ref:DI ("u") [flags 0x2]  <var_decl
0x7fe775410c60 u>)
                (const_int 1 [0x1])))) "/app/example.cpp":8:65 discrim 1 84
{*movdi_internal}
     (expr_list:REG_EQUIV (const:DI (plus:DI (symbol_ref:DI ("u") [flags 0x2] 
<var_decl 0x7fe775410c60 u>)
                (const_int 1 [0x1])))
        (nil)))
(insn 383 466 384 2 (set (reg:DI 1 dx [348])
        (if_then_else:DI (eq (reg:CCZ 17 flags)
                (const_int 0 [0]))
            (reg:DI 1 dx [353])
            (reg:DI 4 si [354]))) "/app/example.cpp":8:65 discrim 1 1451
{*movdicc_noc}
     (expr_list:REG_DEAD (reg:CCZ 17 flags)
        (expr_list:REG_DEAD (reg:DI 4 si [354])
            (nil))))
```

Which is fine (but note the REG_UNUSED note which was not updated).

From pro_and_epilogue's dump:
deleting insn with uid = 22.

Which is totally bogus; I think someone didn't redo REG_UNUSED notes again.