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From: "bergner at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/41742] Unnecessary zero-extension at -O2 but not -O1
Date: Thu, 23 Mar 2023 13:54:19 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D41742

Peter Bergner <bergner at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bergner at gcc dot gnu.org

--- Comment #3 from Peter Bergner <bergner at gcc dot gnu.org> ---
Update: current code (both powerpc64-linux and powerpc64le-linux) still con=
tain
the unneeded rlwinm, but now we've replaced the loop with a call to libc's
memset and we do not shrink-wrap the call due to the use of the non-volatile
r31 in the entry block.=20

foo:
        cmpdi 0,5,0
        std 31,-8(1)
        stdu 1,-128(1)
        mr 31,3
        beq 0,.L4
        mflr 0
        rlwinm 4,4,0,0xff
        std 0,144(1)
        bl memset
        nop
        ld 0,144(1)
        mtlr 0
.L4:
        addi 1,1,128
        mr 3,31
        ld 31,-8(1)
        blr=