On Sat, Jul 25, 2015 at 6:57 AM, Dimitry Andric <dimi...@andric.com> wrote:
> dim added inline comments. > > ================ > Comment at: include/__config:724 > @@ -719,1 +723,3 @@ > +#endif > + > #ifndef _LIBCPP_HAS_NO_ASAN > ---------------- > mclow.lists wrote: > > I think that this needs more exploration; someone needs to look at the > codegen. > > > > return x; > > > > is different from: > > > > return (x); // this is an expression > > > > I suspect that only one will trigger RVO. > > > Would you really think so? I would think the parentheses are superfluous, > and can be removed by parsing stages before it gets to RVO. But I will try > to check the codegen anyway. > Please file a bug if you find any cases where the parenthesized and non-parenthesized form behave differently wrt RVO / NRVO. > Alternatively, since the macro is for 'internal use only', we might try to > just remove the parentheses, e.g.: > > #ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES > # define _LIBCPP_EXPLICIT_MOVE(x) _VSTD::move(x) > #else > # define _LIBCPP_EXPLICIT_MOVE(x) x > #endif > > It is a bit ugly, but at least the code itself does not have to be > littered with #ifdefs. > > > http://reviews.llvm.org/D11394 > > > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits >
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