Apply another batch of fixes from clang-tidy's performance-unnecessary-value-param.

Contains some manual fixes. No functionality change intended.

llvm-svn: 273047
diff --git a/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp b/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
index 91684c2..74c47d1 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
@@ -279,7 +279,7 @@
 
 // Hash an individual attribute \param Attr based on the type of attribute and
 // the form.
-void DIEHash::hashAttribute(DIEValue Value, dwarf::Tag Tag) {
+void DIEHash::hashAttribute(const DIEValue &Value, dwarf::Tag Tag) {
   dwarf::Attribute Attribute = Value.getAttribute();
 
   // Other attribute values use the letter 'A' as the marker, and the value
diff --git a/llvm/lib/CodeGen/AsmPrinter/DIEHash.h b/llvm/lib/CodeGen/AsmPrinter/DIEHash.h
index 44f0ce8..996cd7e 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIEHash.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DIEHash.h
@@ -131,7 +131,7 @@
   void hashLocList(const DIELocList &LocList);
 
   /// \brief Hashes an individual attribute.
-  void hashAttribute(DIEValue Value, dwarf::Tag Tag);
+  void hashAttribute(const DIEValue &Value, dwarf::Tag Tag);
 
   /// \brief Hashes an attribute that refers to another DIE.
   void hashDIEEntry(dwarf::Attribute Attribute, dwarf::Tag Tag,