[clang] [CIR] Upstream global variable linkage types (PR #129072)

[Andy Kaylor via cfe-commits]

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@@ -210,6 +223,193 @@ void CIRGenModule::emitGlobalDefinition(clang::GlobalDecl gd,
   llvm_unreachable("Invalid argument to CIRGenModule::emitGlobalDefinition");
 }
 
+static bool shouldBeInCOMDAT(CIRGenModule &cgm, const Decl &d) {
+  assert(!cir::MissingFeatures::supportComdat());
+
+  if (d.hasAttr<SelectAnyAttr>())
+    return true;
+
+  GVALinkage linkage;
+  if (auto *vd = dyn_cast<VarDecl>(&d))
+    linkage = cgm.getASTContext().GetGVALinkageForVariable(vd);
+  else
+    linkage =
+        cgm.getASTContext().GetGVALinkageForFunction(cast<FunctionDecl>(&d));
+
+  switch (linkage) {
+  case clang::GVA_Internal:
+  case clang::GVA_AvailableExternally:
+  case clang::GVA_StrongExternal:
+    return false;
+  case clang::GVA_DiscardableODR:
+  case clang::GVA_StrongODR:
+    return true;
+  }
+  llvm_unreachable("No such linkage");
+}
+
+// TODO(CIR): this could be a common method between LLVM codegen.
----------------
andykaylor wrote:

Can you do that as part of this change? Maybe move this into ASTContext?

https://github.com/llvm/llvm-project/pull/129072