Re: [scope] Proposing Boost.Scope

From: Andrzej Krzemienski (akrzemi1_at_[hidden])
Date: 2023-04-14 06:27:42

czw., 13 kwi 2023 o 10:43 Andrey Semashev via Boost <boost_at_[hidden]>
napisał(a):

> On 4/13/23 06:08, Darrell Wright via Boost wrote:
> > One thing I learned in my own replacement is that exit_success is
> heavily penalized on MSVC, even when there is no possible exception,
> because of the call to uncaught_exceptions that isn’t optimized.  It’s a
> good thing to document, if not already, as it is surprising.
>
> Well, a certain amount of overhead is expected, since the added
> condition is there and not likely to be optimized away. However, I would
> expect uncaught_exceptions() to be cheap, as it should simply read an
> integer from TLS.

It looks like the call to std::uncaught_exceptions() is not optimized out,
even in -O3:
https://godbolt.org/z/PYEjP5PYY

> I wonder how std::uncaught_exceptions() compares to
> our custom implementation in boost::core::uncaught_exceptions().
> Perhaps, I should benchmark it.
>
>
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