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

[Mingming Liu via llvm-commits]

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

IIUC your point is the new field in `struct GVFlags` should carry 3 states in the field, `Definition`, `Declaration` and `Summary` since there is a known use case for import summaries.

I can see two different ways to do that
1. Rename `importAsDec` to `importType` and make it two bits.
2. Keep the current way to represent def vs decl. For the import summary use case, add another one-bit field.

I like 1 better since join two 1-bit fields to represent 3 states is not very natural. If this sounds good, I could make the change.



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