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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/104914] [MIPS] wrong comparison with scrabbled
 int value
Date: Fri, 07 Jul 2023 05:12:32 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104914

--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #11)
> But I don't have any other notes on my change (nor a testcase).

So I found some notes and it is similar but still different.
We were expanding:
;; insn.j_format.target =3D D.21597_19;
Into
(insn 25 24 26 (set (reg:DI 220)
        (lshiftrt:DI (reg:DI 196 [ D.21584 ])
            (const_int 2 [0x2]))) arch/mips/kernel/jump_label.c:56 -1
     (nil))

(insn 26 25 0 (set (zero_extract:SI (reg/v:SI 208 [ insn ])
            (const_int 26 [0x1a])
            (const_int 6 [0x6]))
        (subreg:SI (reg:DI 220) 4)) arch/mips/kernel/jump_label.c:56 -1
     (nil))

But the subreg there was incorrect.

In this case of this bug, the reg is DI rather than SI. I wonder why we have
that in the first place even though val is the size of SImode ...=