Mordante added a comment.
In D86559#2243583 <https://reviews.llvm.org/D86559#2243583>, @staffantj wrote:
> The use case for this becomes clearer when considering that the attribute
> that will be used 95% of the time is [[unlikely]]. You may have a constructor
> that you wish to ask the compiler to please, please, do not inline this, in a
> particular function, even if the rest of that function is either likely or
> neutral.
At the moment the likelihood is used only for branch prediction and not for
inlining decisions. I'm not sure it would be a good idea to use this attribute
for that duality. If it's wanted to control the inlining of calls at the
callers side I feel a separate attribute would make more sense.
void foo()
{
[[unlikely]] expensive_class q{};
...
}
This looks odd to me and the attribute isn't allowed on the declaration. I
think this looks better:
void foo()
{
[[noinline]] expensive_class q{};
...
}
> if (a)
> [[unlikely]] expensive_class q{};
>
> This could be the case if expensive_class held large static members, for
> instance.
This can be rewritten to be an expression and not a declaration, then the
attribute can be used:
if(a)
[[unlikely]] expensive_class{};
Repository:
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https://reviews.llvm.org/D86559/new/
https://reviews.llvm.org/D86559
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