[PATCH] Emit initializers for selectany globals in comdat-associative sections (PR20889)

[Hans Wennborg]

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Comment at: lib/CodeGen/CGDeclCXX.cpp:335
@@ -334,1 +334,3 @@
     DelayedCXXInitPosition.erase(D);
+  } else if (D->hasAttr<SelectAnyAttr>()) {
+    // SelectAny globals will be comdat-folded. Put the initializer into a COMDAT
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rnk wrote:
> Should we do the same for WeakAttr? What does GCC do?
> 
> I wonder if there is a more general GVA linkage check we should do. Can you add a test for static data members of implicitly instantiated dllexport class templates?
Yes, doing the same for WeakAttr sounds reasonable.

I couldn't observe gcc doing anything special for dynamic initializers of weak objects :/

We do get this right for static data members of implicitly instantiated class templates; it's handled by your code above, and dllexport doesn't change it. I can add a test.

If we want to base this on GVA linkage, it seems to me that the associative comdat method should be applied to all symbols that can be merged, so GVA_StrongODR and GVA_DiscardableODR? But I don't think SelectAny or WeakAttr are reflected in the gva linkage.

http://reviews.llvm.org/D5281