__insn_barrier(3) - NetBSD Manual Pages

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__INSN_BARRIER(3)       NetBSD Library Functions Manual      __INSN_BARRIER(3)


NAME

     __insn_barrier -- compiler reorder barrier


SYNOPSIS

     #include <sys/cdefs.h>

     void
     __insn_barrier();


DESCRIPTION

     The __insn_barrier() macro prevents GCC from moving code across the bar-
     rier.  In other words, the compiler is not allowed to reorder read and
     write commands below the barrier with the code preceding the barrier.
     Like with the volatile type qualifier, __insn_barrier() may be necessary
     in some corner cases to prevent the compiler from misoptimizing.


SEE ALSO

     gcc(1), cdefs(3), mb(9)

     Paul E. McKenney, Memory Barriers: a Hardware View for Software Hackers,
     http://www.rdrop.com/users/paulmck/scalability/paper/whymb.2010.06.07c.pdf,
     June 7, 2010.


HISTORY

     The __insn_barrier() macro first appeared in NetBSD 2.0.

NetBSD 8.0                      January 2, 2011                     NetBSD 8.0