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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/112723] Missed optimization for invariants
 'c+c' when c += -2147483648 and c is a global variable
Date: Mon, 27 Nov 2023 09:51:30 +0000
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X-Bugzilla-Type: changed
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: missed-optimization, TREE
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: pinskia at gcc dot gnu.org
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112723

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
           Keywords|                            |missed-optimization, TREE

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The argument case is only optimized at the RTL level:
Trying 8 -> 9:
    8: {r87:SI=3Dr85:SI-0x80000000;clobber flags:CC;}
      REG_DEAD r85:SI
      REG_UNUSED flags:CC
    9: {r88:SI=3Dr87:SI<<0x1;clobber flags:CC;}
      REG_DEAD r87:SI
      REG_UNUSED flags:CC
Successfully matched this instruction:
(parallel [
        (set (reg:SI 88)
            (ashift:SI (reg/v:SI 85 [ cD.2766 ])
                (const_int 1 [0x1])))
        (clobber (reg:CC 17 flags))
    ])=