llvm dev - Oct 2016 - Is extern_weak a legal linkage for function definitions?

Hi,

The LLVM language reference doesn't say that extern_weak is illegal for
function definitions, but it seems this restriction is enforced in the
code in some places:

https://github.com/llvm-mirror/llvm/blob/master/lib/AsmParser/LLParser.cpp#L4591
https://github.com/llvm-mirror/llvm/blob/master/lib/CodeGen/AsmPrinter/AsmPrinter.cpp#L327


However it is possible to create a bitcode file where a function
definition has extern_weak linkage.  Are these restrictions in
the code wrong, or do we just need to update the language reference?

-Tom

I don't think it should be valid. What are the semantics you would
expect an extern_weak definition to have?

Cheers,
Rafael


On 7 October 2016 at 11:37, Tom Stellard via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Hi,
>
> The LLVM language reference doesn't say that extern_weak is illegal for
> function definitions, but it seems this restriction is enforced in the
> code in some places:
>
>
https://github.com/llvm-mirror/llvm/blob/master/lib/AsmParser/LLParser.cpp#L4591
>
https://github.com/llvm-mirror/llvm/blob/master/lib/CodeGen/AsmPrinter/AsmPrinter.cpp#L327
>
>
> However it is possible to create a bitcode file where a function
> definition has extern_weak linkage.  Are these restrictions in
> the code wrong, or do we just need to update the language reference?
>
> -Tom
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

On Fri, Oct 07, 2016 at 01:47:12PM -0400, Rafael Espíndola
wrote:
> I don't think it should be valid. What are the semantics you would
> expect an extern_weak definition to have?
> 
I'm not sure.  I just have a test case that uses extern_weak, which
crashes the backend, and I'm trying to figure out if the bug is in
the backend or in the test.

-Tom
> Cheers,
> Rafael
> 
> 
> On 7 October 2016 at 11:37, Tom Stellard via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > Hi,
> >
> > The LLVM language reference doesn't say that extern_weak is
illegal for
> > function definitions, but it seems this restriction is enforced in the
> > code in some places:
> >
> >
https://github.com/llvm-mirror/llvm/blob/master/lib/AsmParser/LLParser.cpp#L4591
> >
https://github.com/llvm-mirror/llvm/blob/master/lib/CodeGen/AsmPrinter/AsmPrinter.cpp#L327
> >
> >
> > However it is possible to create a bitcode file where a function
> > definition has extern_weak linkage.  Are these restrictions in
> > the code wrong, or do we just need to update the language reference?
> >
> > -Tom
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev