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[Bug middle-end/70245] [6 Regression] Miscompilation of ICU on i386 with atom tuning starting with r227382


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70245

--- Comment #5 from Vladimir Makarov <vmakarov at gcc dot gnu.org> ---
(In reply to Vladimir Makarov from comment #4)

> 
> I see in peephole a wrong transformation:
> 
>   190: cx:SI=dx:SI
>       REG_DEAD dx:SI
>    95: {cx:SI=cx:SI+[cx:SI];clobber flags:CC;}
> 
> into
> 
>   242: cx:SI=[cx:SI]
>   243: {cx:SI=cx:SI+dx:SI;clobber flags:CC;}

The pattern in question:

(define_peephole2
  [(set (match_operand:SI 0 "register_operand")
        (match_operand:SI 1 "register_operand"))
   (parallel [(set (match_dup 0)
                   (match_operator:SI 3 "commutative_operator"
                     [(match_dup 0)
                      (match_operand:SI 2 "memory_operand")]))
              (clobber (reg:CC FLAGS_REG))])]
  "REGNO (operands[0]) != REGNO (operands[1])
   && GENERAL_REGNO_P (REGNO (operands[0]))
   && GENERAL_REGNO_P (REGNO (operands[1]))"
  [(set (match_dup 0) (match_dup 4))
   (parallel [(set (match_dup 0)
                   (match_op_dup 3 [(match_dup 0) (match_dup 1)]))
              (clobber (reg:CC FLAGS_REG))])]
  "operands[4] = replace_rtx (operands[2], operands[0], operands[1]);")

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