[LLVMdev] Clang's approach to anonymous struct pointer parameters

[Rick Mann]

On Jan 20, 2013, at 5:38, Florian Brandner <flbr at imm.dtu.dk> wrote:

> Hi Rick,
> 
> this is a bug in Clang's LLVM-IR code generator:
> http://llvm.org/bugs/show_bug.cgi?id=14920

Oh, interesting, thanks. 

How do I create a recursive definition like this?

> 
> Best,
> Florian
> 
> On Sunday, January 20, 2013 01:57:37 Rick Mann wrote:
>> For the following code:
>> 
>>    struct XBeePacket;
>> 
>>    typedef void (*CompletionProc)(XBeePacket* inPacket, void* inParam2);
>> 
>>    struct
>>    XBeePacket
>>    {
>>        bool            mField1;
>>        CompletionProc  mCompletionProc;
>>    };
>> 
>> Why does clang emit this IR?
>> 
>>    %struct.XBeePacket = type { i8, {}* }
>> 
>>    define void
>>    @MyCompletionProc(%struct.XBeePacket* %inPacket, i8* %inParam2)
>>        nounwind uwtable ssp
>>    {
>>    entry:
>>      ...
>>    }
>> 
>> It makes the struct field for the completion proc an an anonymous aggregate pointer. Is that better than making the first parameter to MyCompletionProc void* or something similar?
>> 
>> I guess there's no way in LLVM IR to forward-declare in a way that solves this, huh?
> -- 
> Florian Brandner
> Embedded Systems Engineering Group
> Department of Applied Mathematics and Computer Science
> Technical University of Denmark
> Richard Petersens Plads
> Building 322, room 206
> 2800 Lyngby
> Denmark
> 
> phone: +45 45255223
> web: http://www.imm.dtu.dk/~flbr/
> email: flbr at imm.dtu.dk
> 
> 
>