[cfe-dev] checking for virtual members

[Douglas Gregor]

On Nov 2, 2010, at 6:17 PM, John Thompson wrote:

> I have no idea.  Bascially, I just need something that tells me that there won't be any other stuff in the actual object, since vecreturn wants to return the object in a vector register.  Could you tell me which functions or function I should call?

Not without knowing what the semantics are. Please try to nail down exactly what kinds of classes are/aren't allowed with vecreturn, and we can find the right predicate to implement that in Clang. Unless GCC is doing something silly, we should follow their behavior.

	- Doug

> Thanks.
>  
> -John
> On Tue, Nov 2, 2010 at 1:28 PM, Douglas Gregor <dgregor at apple.com> wrote:
> 
> On Nov 2, 2010, at 12:04 PM, John Thompson wrote:
> 
>> >Why? Is this what GCC does?
>> 
>> Yes.  The class example I enclosed previously will build with our gcc, whereas Clang would not, as Clang only allows a strict POD class or struct in the original code.  I just posted a patch on cfe-commits to fix this.
> 
> Okay. This patch uses isDynamicClass(), which means that we still permit classes that involve multiple inheritance. Is that intended? Does it make sense?
> 
> It seems to me that the right language idea might be the C++0x standard-layout class, rather than the idea of a non-dynamic class.
> - Doug
> 
>> -John
>> 
>> On Tue, Nov 2, 2010 at 11:54 AM, Douglas Gregor <dgregor at apple.com> wrote:
>> 
>> On Nov 1, 2010, at 5:05 PM, John Thompson wrote:
>> 
>> > I need a way easily check to make sure a function has no virtual functions, or other stuff that would inject extra stuff into an object or structure, as part of the validation for the vecreturn attribute.  How do I do it?
>> >
>> > Checking the CXXRecordDecl::PlainOldData flag with isPOD doesn't work, because the the strict definition of POD goes too far for this case.
>> 
>> Why? Is this what GCC does?
>> 
>>        - Doug
>> 
>> 
>> 
>> -- 
>> John Thompson
>> John.Thompson.JTSoftware at gmail.com
>> 
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> 
> 
> 
> 
> -- 
> John Thompson
> John.Thompson.JTSoftware at gmail.com
> 
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