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Subject: [Bug target/55981] std::atomic store is split in two smaller stores
Date: Tue, 15 Jan 2013 14:30:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55981

Uros Bizjak <ubizjak at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |ubizjak at gmail dot com
                   |gnu.org                     |
   Target Milestone|---                         |4.7.3

--- Comment #7 from Uros Bizjak <ubizjak at gmail dot com> 2013-01-15 14:29:44 UTC ---
Attached patch generates:

        movabsq $4294967298, %rdx
        subl    $1, %eax
        movq    %rdx, y(%rip)
        movabsq $12884901892, %rdx
        mfence
        movq    %rdx, y(%rip)
        mfence

while non-patched compiler generates:

        movl    $2, y(%rip)
        movl    $1, y+4(%rip)
        subl    $1, %eax
        mfence
        movl    $4, y(%rip)
        movl    $3, y+4(%rip)
        mfence