[llvm] [ThinLTO]Record import type in GlobalValueSummary::GVFlags (PR #87597)

[Teresa Johnson via llvm-commits]

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@@ -737,6 +737,7 @@ lltok::Kind LLLexer::LexIdentifier() {
   KEYWORD(live);
   KEYWORD(dsoLocal);
   KEYWORD(canAutoHide);
+  KEYWORD(importAsDec);
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teresajohnson wrote:

Without either a definition or declaration in the importing module, how do we even know what symbol a summary and its attributes apply to and what do we do with them? Trying to understand the mechanics of how a "summary" import works before we reserve a flag bit for that case. Couldn't we just mark it as a declaration import which would essentially be a no-op if a declaration/def already exists in the module?

https://github.com/llvm/llvm-project/pull/87597