r350920 - [Sema] Make canPassInRegisters return true if the CXXRecordDecl passed

[John McCall via cfe-commits]

On 16 Jan 2019, at 9:13, Aaron Ballman wrote:

> On Wed, Jan 16, 2019 at 1:57 AM Akira Hatanaka <ahatanaka at apple.com> 
> wrote:
>>
>> Yes, the behavior of the compiler doesn’t match what’s explained 
>> in the documentation anymore.
>>
>> Please take a look at the attached patch, which updates the 
>> documentation.
>
> Patch mostly LGTM, but I did have one wording suggestion.
>
>> diff --git a/include/clang/Basic/AttrDocs.td 
>> b/include/clang/Basic/AttrDocs.td
>> index 5773a92c9c..ca3cfcf9b2 100644
>> --- a/include/clang/Basic/AttrDocs.td
>> +++ b/include/clang/Basic/AttrDocs.td
>> @@ -2478,15 +2478,20 @@ def TrivialABIDocs : Documentation {
>>    let Category = DocCatVariable;
>>    let Content = [{
>>  The ``trivial_abi`` attribute can be applied to a C++ class, struct, 
>> or union.
>> -It instructs the compiler to pass and return the type using the C 
>> ABI for the
>> +``trivial_abi`` has the following effects:
>> +
>> +- It instructs the compiler to pass and return the type using the C 
>> ABI for the
>>  underlying type when the type would otherwise be considered 
>> non-trivial for the
>>  purpose of calls.
>> -A class annotated with `trivial_abi` can have non-trivial 
>> destructors or copy/move constructors without automatically becoming 
>> non-trivial for the purposes of calls. For example:
>> +- It makes the destructor and copy and move constructors of the 
>> class trivial
>> +that would otherwise be considered non-trivial under the C++ ABI 
>> rules.
>
> How about: It makes the destructor, copy constructors, and move
> constructors of the class trivial even if they would otherwise be
> non-trivial under the C++ ABI rules.

Let's not say that it makes them trivial, because it doesn't.  It causes
their immediate non-triviality to be ignored for the purposes of 
deciding
whether the type can be passed in registers.

John.