[llvm] [ThinLTO] Populate declaration import status except for distributed ThinLTO under a default-off new option (PR #88024)

[Jan Voung via llvm-commits]

================
@@ -1034,22 +1106,31 @@ void llvm::ComputeCrossModuleImport(
         // we convert such variables initializers to "zeroinitializer".
         // See processGlobalForThinLTO.
         if (!Index.isWriteOnly(GVS))
-          for (const auto &VI : GVS->refs())
-            NewExports.insert(VI);
+          for (const auto &VI : GVS->refs()) {
+            // Try to emplace the declaration entry. If a definition entry
+            // already exists for key `VI`, this is a no-op.
+            NewExports.try_emplace(VI, GlobalValueSummary::Declaration);
+          }
       } else {
         auto *FS = cast<FunctionSummary>(S);
-        for (const auto &Edge : FS->calls())
-          NewExports.insert(Edge.first);
-        for (const auto &Ref : FS->refs())
-          NewExports.insert(Ref);
+        for (const auto &Edge : FS->calls()) {
+          // Try to emplace the declaration entry. If a definition entry
+          // already exists for key `VI`, this is a no-op.
+          NewExports.try_emplace(Edge.first, GlobalValueSummary::Declaration);
+        }
+        for (const auto &Ref : FS->refs()) {
+          // Try to emplace the declaration entry. If a definition entry
+          // already exists for key `VI`, this is a no-op.
+          NewExports.try_emplace(Ref, GlobalValueSummary::Declaration);
+        }
       }
     }
-    // Prune list computed above to only include values defined in the exporting
-    // module. We do this after the above insertion since we may hit the same
-    // ref/call target multiple times in above loop, and it is more efficient to
-    // avoid a set lookup each time.
+    //  Prune list computed above to only include values defined in the
----------------
jvoung wrote:

nit: can keep the original single space in the comment?

https://github.com/llvm/llvm-project/pull/88024