[Support] Move DJB hash to support. NFC

This patch moves the DJB hash to support. This is consistent with other
hashing algorithms living there. The hash is used by the DWARF
accelerator tables. We're doing this now because the hashing function is
needed by dsymutil and we don't want to link against libBinaryFormat.

Differential revision: https://reviews.llvm.org/D42594

llvm-svn: 323616

include/llvm/BinaryFormat/Dwarf.h

@@ -528,9 +528,6 @@ private:
 /// Constants that define the DWARF format as 32 or 64 bit.
 enum DwarfFormat : uint8_t { DWARF32, DWARF64 };
 
-/// The Bernstein hash function used by the accelerator tables.
-uint32_t djbHash(StringRef Buffer, uint32_t H = 5381);
-
 } // End of namespace dwarf
 
 } // End of namespace llvm

include/llvm/Support/DJB.h

@@ -0,0 +1,25 @@
+//===-- llvm/Support/DJB.h ---DJB Hash --------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for the DJ Bernstein hash function.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_DJB_H
+#define LLVM_SUPPORT_DJB_H
+
+#include "llvm/ADT/StringRef.h"
+
+namespace llvm {
+
+/// The Bernstein hash function used by the DWARF accelerator tables.
+uint32_t djbHash(StringRef Buffer, uint32_t H = 5381);
+} // namespace llvm
+
+#endif // LLVM_SUPPORT_DJB_H

lib/BinaryFormat/Dwarf.cpp

@@ -589,9 +589,3 @@ bool llvm::dwarf::isValidFormForVersion(Form F, unsigned Version,
   }
   return ExtensionsOk;
 }
-
-uint32_t llvm::dwarf::djbHash(StringRef Buffer, uint32_t H) {
-  for (char C : Buffer.bytes())
-    H = ((H << 5) + H) + C;
-  return H;
-}

lib/CodeGen/AsmPrinter/DwarfAccelTable.h

@@ -23,6 +23,7 @@
 #include "llvm/CodeGen/DwarfStringPoolEntry.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/DJB.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/raw_ostream.h"
@@ -192,7 +193,7 @@ private:
 
     HashData(StringRef S, DwarfAccelTable::DataArray &Data)
         : Str(S), Data(Data) {
-      HashValue = dwarf::djbHash(S);
+      HashValue = djbHash(S);
     }
 
 #ifndef NDEBUG

lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp

@@ -13,6 +13,7 @@
 #include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/DebugInfo/DWARF/DWARFRelocMap.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/DJB.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstddef>
@@ -236,7 +237,7 @@ AppleAcceleratorTable::equal_range(StringRef Key) const {
     return make_range(ValueIterator(), ValueIterator());
 
   // Find the bucket.
-  unsigned HashValue = dwarf::djbHash(Key);
+  unsigned HashValue = djbHash(Key);
   unsigned Bucket = HashValue % Hdr.NumBuckets;
   unsigned BucketBase = sizeof(Hdr) + Hdr.HeaderDataLength;
   unsigned HashesBase = BucketBase + Hdr.NumBuckets * 4;

lib/Support/CMakeLists.txt

@@ -59,6 +59,7 @@ add_llvm_library(LLVMSupport
   DebugCounter.cpp
   DeltaAlgorithm.cpp
   DAGDeltaAlgorithm.cpp
+  DJB.cpp
   Error.cpp
   ErrorHandling.cpp
   FileUtilities.cpp

lib/Support/DJB.cpp

@@ -0,0 +1,20 @@
+//===-- Support/DJB.cpp ---DJB Hash -----------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for the DJ Bernstein hash function.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/DJB.h"
+
+uint32_t llvm::djbHash(StringRef Buffer, uint32_t H) {
+  for (char C : Buffer.bytes())
+    H = ((H << 5) + H) + C;
+  return H;
+}