[cfe-dev] libc++ and large stack frames

[Friedman, Eli via cfe-dev]

On 5/31/2018 1:07 PM, Erik van der Poel via cfe-dev wrote:
> This is a proposal to add a configuration option to disable 
> _LIBCPP_INLINE_VISIBILITY, which causes large stack frames in 
> non-optimized builds because it uses the always_inline attribute to 
> force significant amounts of inlining of libc++ code.
>
> The new configuration option could be called 
> _LIBCPP_DISABLE_INLINE_VISIBILITY.
>
> Note that _LIBCPP_INLINE_VISIBILITY and _LIBCPP_ALWAYS_INLINE have 
> identical definitions. One could be renamed to the other or both could 
> be renamed to _LIBCPP_HIDE_FROM_ABI as part of this work.
>
> Alternatives considered and rejected:
>
> 1. Remove __attribute__((__always_inline__)) from all include/__config 
> macros.
> 2. Add _LIBCPP_DISABLE_ALWAYS_INLINE to control whether or not 
> __always_inline__ is included in any __config macro.
> 3. Use the existing _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS to control 
> both __visibility__ and __always_inline__.
> 4. Use the existing _LIBCPP_ABI_UNSTABLE to control 
> _LIBCPP_INLINE_VISIBILITY.

5. Start using __attribute__((internal_linkage)) instead, so a 
configuration option isn't necessary.  See 
http://lists.llvm.org/pipermail/cfe-dev/2016-October/051151.html .

-Eli

-- 
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