Merge commit 'cf66110ca9e9' from swift/release/6.2 into stable/20240723

Author: git apple-llvm automerger

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -3119,6 +3119,9 @@ llvm::DIModule *CGDebugInfo::getOrCreateModuleRef(ASTSourceDescriptor Mod,
     std::string Remapped = remapDIPath(Path);
     StringRef Relative(Remapped);
     StringRef CompDir = TheCU->getDirectory();
+    if (CompDir.empty())
+      return Remapped;
+
     if (Relative.consume_front(CompDir))
       Relative.consume_front(llvm::sys::path::get_separator());