[Support] Replace HashString with djbHash.

This removes the HashString function from StringExtraces and replaces
its uses with calls to djbHash from DJB.h

This is *almost* NFC. While the algorithm is identical, the djbHash
implementation in StringExtras used 0 as its seed while the
implementation in DJB uses 5381. The latter has been shown to result in
less collisions and improved avalanching.

https://reviews.llvm.org/D43615
(cherry picked from commit 77f7f965bc9499a9ae768a296ca5a1f7347d1d2c)

llvm-svn: 326081

1 files changed, 3 insertions, 3 deletions

diff --git a/clang/lib/Frontend/CacheTokens.cpp b/clang/lib/Frontend/CacheTokens.cpp
index 851ea25e9b1..f3569edc695 100644
--- a/clang/lib/Frontend/CacheTokens.cpp
+++ b/clang/lib/Frontend/CacheTokens.cpp
@@ -21,8 +21,8 @@
 #include "clang/Lex/Lexer.h"
 #include "clang/Lex/PTHManager.h"
 #include "clang/Lex/Preprocessor.h"
-#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringMap.h"
+#include "llvm/Support/DJB.h"
 #include "llvm/Support/EndianStream.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -128,7 +128,7 @@ public:
   typedef unsigned offset_type;
 
   static hash_value_type ComputeHash(PTHEntryKeyVariant V) {
-    return llvm::HashString(V.getString());
+    return llvm::djbHash(V.getString());
   }
 
   static std::pair<unsigned,unsigned>
@@ -625,7 +625,7 @@ public:
   typedef unsigned offset_type;
 
   static hash_value_type ComputeHash(PTHIdKey* key) {
-    return llvm::HashString(key->II->getName());
+    return llvm::djbHash(key->II->getName());
   }
 
   static std::pair<unsigned,unsigned>