[Bug target/55981] std::atomic store is split in two smaller stores

[ubizjak at gmail dot com]

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