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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug rtl-optimization/101200] Unneeded AND after shift
Date: Thu, 24 Jun 2021 20:37:38 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101200

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|tree-optimization           |rtl-optimization
           Keywords|                            |missed-optimization
           Severity|normal                      |enhancement

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This does not make sense:
Trying 12 -> 14:
   12: {r93:QI=3Dr82:QI 0>>0x4;clobber flags:CC;}
      REG_DEAD r82:QI
      REG_UNUSED flags:CC
   14: {r95:DI=3Dr93:QI#0&0xf;clobber flags:CC;}
      REG_UNUSED flags:CC
      REG_DEAD r93:QI
Failed to match this instruction:
(parallel [
        (set (reg:DI 95 [ a ])
            (zero_extract:DI (subreg:HI (reg:QI 82 [ d.0_1 ]) 0)
                (const_int 4 [0x4])
                (const_int 4 [0x4])))
        (clobber (reg:CC 17 flags))
    ])

How can you have a subreg of HI and then get a zero_extract of DI?=