Revert "[Support] Replace HashString with djbHash."

It looks like some of our tests depend on the ordering of hashed values.
I'm reverting my changes while I try to reproduce and fix this locally.

Failing builds:

  lab.llvm.org:8011/builders/lld-x86_64-darwin13/builds/18388
  lab.llvm.org:8011/builders/clang-cmake-x86_64-sde-avx512-linux/builds/6743
  lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-windows10pro-fast/builds/15607

llvm-svn: 326082

clang/lib/Frontend/ASTUnit.cpp

@@ -35,9 +35,9 @@
 #include "clang/Serialization/ASTReader.h"
 #include "clang/Serialization/ASTWriter.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/CrashRecoveryContext.h"
-#include "llvm/Support/DJB.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Mutex.h"
@@ -798,7 +798,7 @@ namespace {
 
 /// \brief Add the given macro to the hash of all top-level entities.
 void AddDefinedMacroToHash(const Token &MacroNameTok, unsigned &Hash) {
-  Hash = llvm::djbHash(MacroNameTok.getIdentifierInfo()->getName(), Hash);
+  Hash = llvm::HashString(MacroNameTok.getIdentifierInfo()->getName(), Hash);
 }
 
 /// \brief Preprocessor callback class that updates a hash value with the names 
@@ -834,16 +834,16 @@ void AddTopLevelDeclarationToHash(Decl *D, unsigned &Hash) {
       if (!EnumD->isScoped()) {
         for (const auto *EI : EnumD->enumerators()) {
           if (EI->getIdentifier())
-            Hash = llvm::djbHash(EI->getIdentifier()->getName(), Hash);
+            Hash = llvm::HashString(EI->getIdentifier()->getName(), Hash);
         }
       }
     }
 
     if (ND->getIdentifier())
-      Hash = llvm::djbHash(ND->getIdentifier()->getName(), Hash);
+      Hash = llvm::HashString(ND->getIdentifier()->getName(), Hash);
     else if (DeclarationName Name = ND->getDeclName()) {
       std::string NameStr = Name.getAsString();
-      Hash = llvm::djbHash(NameStr, Hash);
+      Hash = llvm::HashString(NameStr, Hash);
     }
     return;
   }
@@ -851,7 +851,7 @@ void AddTopLevelDeclarationToHash(Decl *D, unsigned &Hash) {
   if (ImportDecl *ImportD = dyn_cast<ImportDecl>(D)) {
     if (Module *Mod = ImportD->getImportedModule()) {
       std::string ModName = Mod->getFullModuleName();
-      Hash = llvm::djbHash(ModName, Hash);
+      Hash = llvm::HashString(ModName, Hash);
     }
     return;
   }

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::djbHash(V.getString());
+    return llvm::HashString(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::djbHash(key->II->getName());
+    return llvm::HashString(key->II->getName());
   }
 
   static std::pair<unsigned,unsigned>

clang/lib/Lex/PTHLexer.cpp

@@ -23,8 +23,8 @@
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Lex/Token.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/Support/DJB.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/FileSystem.h"
@@ -336,7 +336,7 @@ public:
   using offset_type = unsigned;
 
   static hash_value_type ComputeHash(internal_key_type x) {
-    return llvm::djbHash(x.second);
+    return llvm::HashString(x.second);
   }
 
   static std::pair<unsigned, unsigned>
@@ -396,7 +396,7 @@ public:
   }
 
   static hash_value_type ComputeHash(const internal_key_type& a) {
-    return llvm::djbHash(StringRef(a.first, a.second));
+    return llvm::HashString(StringRef(a.first, a.second));
   }
 
   // This hopefully will just get inlined and removed by the optimizer.

clang/lib/Serialization/ASTCommon.cpp

@@ -16,7 +16,7 @@
 #include "clang/AST/DeclObjC.h"
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Serialization/ASTDeserializationListener.h"
-#include "llvm/Support/DJB.h"
+#include "llvm/ADT/StringExtras.h"
 
 using namespace clang;
 
@@ -171,7 +171,7 @@ unsigned serialization::ComputeHash(Selector Sel) {
   unsigned R = 5381;
   for (unsigned I = 0; I != N; ++I)
     if (IdentifierInfo *II = Sel.getIdentifierInfoForSlot(I))
-      R = llvm::djbHash(II->getName(), R);
+      R = llvm::HashString(II->getName(), R);
   return R;
 }
 

clang/lib/Serialization/ASTReader.cpp

@@ -106,7 +106,6 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compression.h"
 #include "llvm/Support/Compiler.h"
-#include "llvm/Support/DJB.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -871,7 +870,7 @@ ASTSelectorLookupTrait::ReadData(Selector, const unsigned char* d,
 }
 
 unsigned ASTIdentifierLookupTraitBase::ComputeHash(const internal_key_type& a) {
-  return llvm::djbHash(a);
+  return llvm::HashString(a);
 }
 
 std::pair<unsigned, unsigned>

clang/lib/Serialization/ASTWriter.cpp

@@ -82,13 +82,13 @@
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Bitcode/BitCodes.h"
 #include "llvm/Bitcode/BitstreamWriter.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compression.h"
-#include "llvm/Support/DJB.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/EndianStream.h"
 #include "llvm/Support/Error.h"
@@ -3582,7 +3582,7 @@ public:
   bool needDecls() const { return NeedDecls; }
 
   static hash_value_type ComputeHash(const IdentifierInfo* II) {
-    return llvm::djbHash(II->getName());
+    return llvm::HashString(II->getName());
   }
 
   bool isInterestingIdentifier(const IdentifierInfo *II) {

clang/lib/Serialization/GlobalModuleIndex.cpp

@@ -21,9 +21,9 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Bitcode/BitstreamReader.h"
 #include "llvm/Bitcode/BitstreamWriter.h"
-#include "llvm/Support/DJB.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/LockFileManager.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -81,7 +81,7 @@ public:
   }
 
   static hash_value_type ComputeHash(const internal_key_type& a) {
-    return llvm::djbHash(a);
+    return llvm::HashString(a);
   }
 
   static std::pair<unsigned, unsigned>
@@ -697,7 +697,7 @@ public:
   typedef unsigned offset_type;
 
   static hash_value_type ComputeHash(key_type_ref Key) {
-    return llvm::djbHash(Key);
+    return llvm::HashString(Key);
   }
 
   std::pair<unsigned,unsigned>

lld/include/lld/Core/SymbolTable.h

@@ -12,7 +12,7 @@
 
 #include "lld/Common/LLVM.h"
 #include "llvm/ADT/DenseSet.h"
-#include "llvm/Support/DJB.h"
+#include "llvm/ADT/StringExtras.h"
 #include <cstring>
 #include <map>
 #include <vector>
@@ -65,7 +65,7 @@ private:
     static StringRef getEmptyKey() { return StringRef(); }
     static StringRef getTombstoneKey() { return StringRef(" ", 1); }
     static unsigned getHashValue(StringRef const val) {
-      return llvm::djbHash(val);
+      return llvm::HashString(val);
     }
     static bool isEqual(StringRef const lhs, StringRef const rhs) {
       return lhs.equals(rhs);

lldb/source/Utility/ConstString.cpp

@@ -11,10 +11,10 @@
 
 #include "lldb/Utility/Stream.h"
 
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/iterator.h"            // for iterator_facade_base
 #include "llvm/Support/Allocator.h"       // for BumpPtrAllocator
-#include "llvm/Support/DJB.h"             // for djbHash
 #include "llvm/Support/FormatProviders.h" // for format_provider
 #include "llvm/Support/RWMutex.h"
 #include "llvm/Support/Threading.h"
@@ -171,7 +171,7 @@ public:
 
 protected:
   uint8_t hash(const llvm::StringRef &s) const {
-    uint32_t h = llvm::djbHash(s);
+    uint32_t h = llvm::HashString(s);
     return ((h >> 24) ^ (h >> 16) ^ (h >> 8) ^ h) & 0xff;
   }
 

llvm/include/llvm/ADT/StringExtras.h

@@ -232,6 +232,19 @@ void SplitString(StringRef Source,
                  SmallVectorImpl<StringRef> &OutFragments,
                  StringRef Delimiters = " \t\n\v\f\r");
 
+/// HashString - Hash function for strings.
+///
+/// This is the Bernstein hash function.
+//
+// FIXME: Investigate whether a modified bernstein hash function performs
+// better: http://eternallyconfuzzled.com/tuts/algorithms/jsw_tut_hashing.aspx
+//   X*33+c -> X*33^c
+inline unsigned HashString(StringRef Str, unsigned Result = 0) {
+  for (StringRef::size_type i = 0, e = Str.size(); i != e; ++i)
+    Result = Result * 33 + (unsigned char)Str[i];
+  return Result;
+}
+
 /// Returns the English suffix for an ordinal integer (-st, -nd, -rd, -th).
 inline StringRef getOrdinalSuffix(unsigned Val) {
   // It is critically important that we do this perfectly for

llvm/lib/Support/StringMap.cpp

@@ -14,7 +14,6 @@
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/Compiler.h"
-#include "llvm/Support/DJB.h"
 #include "llvm/Support/MathExtras.h"
 #include <cassert>
 
@@ -83,7 +82,7 @@ unsigned StringMapImpl::LookupBucketFor(StringRef Name) {
     init(16);
     HTSize = NumBuckets;
   }
-  unsigned FullHashValue = djbHash(Name);
+  unsigned FullHashValue = HashString(Name);
   unsigned BucketNo = FullHashValue & (HTSize-1);
   unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1);
 
@@ -137,7 +136,7 @@ unsigned StringMapImpl::LookupBucketFor(StringRef Name) {
 int StringMapImpl::FindKey(StringRef Key) const {
   unsigned HTSize = NumBuckets;
   if (HTSize == 0) return -1;  // Really empty table?
-  unsigned FullHashValue = djbHash(Key);
+  unsigned FullHashValue = HashString(Key);
   unsigned BucketNo = FullHashValue & (HTSize-1);
   unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1);