fix(gcov): write current_working_directory to .gcno file

[PikachuHyA]

fix #121368

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: PikachuHy (PikachuHyA)

Changes

fix #121368

---

Full diff: https://github.com/llvm/llvm-project/pull/121369.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp (+7-2)

diff --git a/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp b/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
index f9be7f933d31e4..fe476038498194 100644
--- a/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
@@ -973,8 +973,13 @@ bool GCOVProfiler::emitProfileNotes(
         out.write(Tmp, 4);
       }
       write(Stamp);
-      if (Version >= 90)
-        writeString(""); // unuseful current_working_directory
+      if (Version >= 90) {
+        SmallString<256> CWD;
+        llvm::sys::fs::current_path(CWD);
+        // the current_working_directory is used by gcov
+        // if the source file is relative path
+        writeString(CWD);
+      }
       if (Version >= 80)
         write(0); // unuseful has_unexecuted_blocks