On Wed, Oct 29, 2014 at 11:07 PM, Andi Kleen <a...@linux.intel.com> wrote: >> >> Hmm, can't the insns themselves properly clobber/use memory? > > The transactions don't really use the memory. They just guard it, > like a lock. > > So the intrinsic doesn't know what memory is used inside the transaction, > but the accesses still cannot be moved out. > > I think a barrier is the only sensible option. > >> I suppose they are UNSPEC_VOLATILE anyway, right? > > That doesn't have any barrier semantics by itself, does it? >
Do you have a testcase to show it makes a difference? -- H.J.
