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

[eugeni.stepanov at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55981



--- Comment #1 from Evgeniy Stepanov <eugeni.stepanov at gmail dot com> 
2013-01-14 22:45:30 UTC ---

Disassembly of the loop in ff() function:



  4007c0:       movl   $0x2,0x2008de(%rip)        # 6010a8 <y>

  4007ca:       movl   $0x1,0x2008d8(%rip)        # 6010ac <y+0x4>

  4007d4:       sub    $0x1,%eax

  4007d7:       mfence 

  4007da:       movl   $0x4,0x2008c4(%rip)        # 6010a8 <y>

  4007e4:       movl   $0x3,0x2008be(%rip)        # 6010ac <y+0x4>

  4007ee:       mfence 

  4007f1:       jne    4007c0 <_Z2ffv+0xb0>



Does not look atomic.

Has all the proper fences, though.