A tweak to HWPMC hooks to improve code generation

[Rang, Anton]

The HWPMC hooks are never invoked except when using the soft PMC feature for performance monitoring. This trivial patch hints as much to the compiler, which then moves some fairly lengthy code sequences out of the locking primitives (in particular), reducing their runtime footprint.

This patch was reviewed by Attilio Rao.

Anton

-------------- next part --------------
A non-text attachment was scrubbed...
Name: pmckern.diff
Type: application/octet-stream
Size: 810 bytes
Desc: pmckern.diff
URL: <http://lists.freebsd.org/pipermail/freebsd-current/attachments/20131223/cb9bdd03/attachment.obj>