[PGO] Do not attach VP metadata if value count at site is 0 [NFC] 

llvm-svn: 266335
diff --git a/llvm/lib/ProfileData/InstrProf.cpp b/llvm/lib/ProfileData/InstrProf.cpp
index 7f4a87a..f1a6ce9 100644
--- a/llvm/lib/ProfileData/InstrProf.cpp
+++ b/llvm/lib/ProfileData/InstrProf.cpp
@@ -636,6 +636,8 @@
                        InstrProfValueKind ValueKind, uint32_t SiteIdx,
                        uint32_t MaxMDCount) {
   uint32_t NV = InstrProfR.getNumValueDataForSite(ValueKind, SiteIdx);
+  if (!NV)
+    return;
 
   uint64_t Sum = 0;
   std::unique_ptr<InstrProfValueData[]> VD =