[ThinLTO] Deduplicate function index loading into shared helper (NFC)

Add a shared helper routine to read the function index from a file
and create/return the function index object. Use it in llvm-link and
llvm-lto.

llvm-svn: 253903

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/include/llvm/Object/FunctionIndexObjectFile.h b/llvm/include/llvm/Object/FunctionIndexObjectFile.h
index 92b670db49a..511a237881e 100644
--- a/llvm/include/llvm/Object/FunctionIndexObjectFile.h
+++ b/llvm/include/llvm/Object/FunctionIndexObjectFile.h
@@ -99,6 +99,13 @@ public:
                                  StringRef FunctionName);
 };
 }
+
+/// Parse the function index out of an IR file and return the function
+/// index object if found, or nullptr if not.
+ErrorOr<std::unique_ptr<FunctionInfoIndex>>
+getFunctionIndexForFile(StringRef Path,
+                        DiagnosticHandlerFunction DiagnosticHandler,
+                        const Module *ExportingModule = nullptr);
 }
 
 #endif