[PATCH] Do not split variables definitions into 2 DIEs.

[Frédéric Riss]

> On 20 Oct 2014, at 14:06, David Blaikie <dblaikie at gmail.com> wrote:
> 
> I've checked this out on the GDB test suite & it seems fine.

Thanks a lot!

> Looking at the code itself, I think it could be made a bit more obvious/uniform to have VariableDIE always refer to the definition and have just a single conditional to decide whether to attach the DW_AT_specification or not.

I suppose that’s the diff you attached? I’ll review it tomorrow

> Actually this works pretty well & even adds another source fidelity benefit, allowing the definition, while out-of-line of the class, to be attributed to the scope in which the definition occurs (eg: namespace x { struct foo { static int i; }; int foo::i; } - putting the definition in namespace 'x' instead of just forcing it out to the global namespace) and exposes a bug in Clang where the definition is scoped to the decl context instead of the lexical context. (patch attached to show a slightly short-sighted fix there)

I had seen that and I think I even know where the code is wrong. But the patch you attached for it isn’t the right one.

Fred

> If we did a few more smart things in the frontend, we could get better fidelity for declarations/definitions of namespace/global variables - removing the weird special case introduced with my patch. Probably the right thing here is to optimize in the frontend, if the definition appears in the decl context (eg: if the global variable's decl context is the same as the lexical context) then just produce the definition. If the decl and lexical context differ, produce both a declaration (in the decl context) and a definition (in the lexical context) - this would be the best source fidelity, but probably isn't too worthwhile.
> 
> Oh, and if we wanted to be really good here, we could make sure we emit any attributes onto the definition that differ from the declaration - note GCC does the right thing here, putting DW_AT_decl_line/file on the definitions if the line/file happens to be different from the declaration's line/file. We don't do that - we just put nothing on the definition (& I don't think we do this for function declarations/definitions either (again, here, GCC gets this right)... could, but probably not important)
> 
> 
> 
> On Thu, Oct 16, 2014 at 8:46 AM, Frederic Riss <friss at apple.com <mailto:friss at apple.com>> wrote:
> ping
> 
> http://reviews.llvm.org/D5457 <http://reviews.llvm.org/D5457>
> 
> 
> 
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu <mailto:llvm-commits at cs.uiuc.edu>
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits <http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits>
> 
> <static_var_def.diff><global_var.diff>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20141020/fbab2173/attachment.html>