[libcxx-commits] [PATCH] D65667: [libcxx] Avoid destructor call for error_category singletons

Chris Bowler via Phabricator via libcxx-commits libcxx-commits at lists.llvm.org
Thu Jun 23 14:08:02 PDT 2022

cebowleratibm added inline comments.

Comment at: libcxx/src/ios.cpp:62
+    _LIBCPP_NO_DESTROY constinit
+    static IostreamErrorHelper s;
+    return s.iostream_error_category;
hubert.reinterpretcast wrote:
> ldionne wrote:
> > Actually, since those are `constinit`, I think we could even define them at file scope and skip the function-local static. Thoughts?
> That makes sense. It does have an advantage in cases where `_LIBCPP_NO_DESTROY` is not effective.
If `_LIBCPP_NO_DESTROY` is not effective, doesn't that mean that the user will pay the startup to register the atexit destruction, even if the category singleton is never used?  I think the benefit of the static local remains: that you're not paying for it unless it's used.  If `_LIBCPP_NO_DESTROY` is supported then there's no benefit to using static locals.  Are we ok imposing the load time cost when the library is built without `_LIBCPP_NO_DESTROY` support?

  rG LLVM Github Monorepo



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