[lld] [lld][COFF][LTO] Implement /opt:emitllvm option (PR #66964)

[Martin Storsjö via llvm-commits]

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@@ -2393,7 +2395,8 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
   // If -thinlto-index-only is given, we should create only "index
   // files" and not object files. Index file creation is already done
   // in addCombinedLTOObject, so we are done if that's the case.
-  if (config->thinLTOIndexOnly)
+  // Likewise, for /emitllvm we only emit bitcode.
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mstorsjo wrote:

The option isn't `/emitllvm` but `/opt:emitllvm`.

https://github.com/llvm/llvm-project/pull/66964