[cfe-commits] r50262 - in /cfe/trunk: include/clang/AST/Attr.h include/clang/Parse/AttributeList.h lib/Parse/AttributeList.cpp lib/Sema/Sema.h lib/Sema/SemaDecl.cpp

[Nuno Lopes]

Well, at least the unused and deprecated attrs could live with such type 
attributes. aligned could probably go to the ASTContext and maybe 
packed+ms_struct+gcc_struct as well. packed could also live in RecordType.
Well I know that implementing the transparent_union attribute is a bit 
harder than those mentioned above, but I really need that working in order 
to compile PHP :P

Anyone else?

Nuno


----- Original Message ----- 
From: "Christopher Lamb" <christopher.lamb at gmail.com>
To: "Nuno Lopes" <nunoplopes at sapo.pt>
Cc: <cfe-commits at cs.uiuc.edu>
Sent: Saturday, April 26, 2008 4:36 AM
Subject: Re: [cfe-commits] r50262 - in /cfe/trunk: include/clang/AST/Attr.h 
include/clang/Parse/AttributeList.h lib/Parse/AttributeList.cpp 
lib/Sema/Sema.h lib/Sema/SemaDecl.cpp


> Nuno,
>
> Handling extra type attributes can be a bit complicated given that
> the type system and type conversion are core operations at the heart
> of the front-end. To implement address space qualified types has
> required adding a new wrapper type (ASQualType) and supporting this
> type throughout clang.
>
> It sounds like your new type attribute may be more narrowly
> applicable to RecordTypes, but I don't think what you want can be
> solved as easily as putting the Decl's type attributes on the Type
> object itself. You can take a look at where ASQualType has been
> introduced to see how essentially adding a single attribute (address
> space) for a type, not only involves adding storage for that
> attribute in the type system, but how it must be handled robustly
> throughout the type modifications that happen in the front-end.
>
> Thinking about adding an extra field for Record types, or a wrapper
> object for record types, are two ways of getting the information
> through to code gen. It would also be informative to see where in the
> code Record types are modified so that you could make a decision
> about how hard it will be to propagate the information through.
>
> In all, adding such an attribute is not a quick task. I could never
> have done the ASQualType stuff in GCC, so I think there is hope. Good
> luck!
> --
> Chris
>
> On Apr 25, 2008, at 2:54 AM, Nuno Lopes wrote:
>
>> Hi,
>>
>> I was trying to implement the transparent_union type attribute, but
>> I think
>> we need some additional API to handle it. I think we should add the
>> attribute API as found in Decl to Type (i.e. addAttr(), getAttrs
>> (), ...).
>> This could be used to implement this attribute and all the others type
>> attributes
>> (http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Type-Attributes.html).
>> Alternatively we could just add an ad-hoc field to the RecordType
>> struct to
>> record if it's a transparent union or not, which also makes sense.
>>
>> Please give me some feedback.
>>
>> Thanks,
>> Nuno
>>
>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=50262&view=rev
>>> Log:
>>> initial support for recognizing __transparent_union__ attributes
>>> comments on the ML will follow
>>> =====================================================================
>>> =========
>>> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Fri Apr 25 04:32:00 2008
>>> @@ -2419,6 +2422,29 @@
>>>                             Idx.getZExtValue(),
>>> FirstArg.getZExtValue()));
>>> }
>>>
>>> +void Sema::HandleTransparentUnionAttribute(Decl *d, AttributeList
>>> *rawAttr) {
>>> +  // check the attribute arguments.
>>> +  if (rawAttr->getNumArgs() != 0) {
>>> +    Diag(rawAttr->getLoc(),
>>> diag::err_attribute_wrong_number_arguments,
>>> +         std::string("0"));
>>> +    return;
>>> +  }
>>> +
>>> +  TypeDecl *decl = dyn_cast<TypeDecl>(d);
>>> +
>>> +  if (!decl || !Context.getTypeDeclType(decl)->isUnionType()) {
>>> +    Diag(rawAttr->getLoc(), diag::warn_attribute_wrong_decl_type,
>>> +         "transparent_union", "union");
>>> +    return;
>>> +  }
>>> +
>>> +  QualType QTy = Context.getTypeDeclType(decl);
>>> +  const RecordType *Ty = QTy->getAsUnionType();
>>> +
>>> +// FIXME
>>> +// Ty->addAttr(new TransparentUnionAttr());
>>> +}
>>> +
>>
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>
> --
> Christopher Lamb