From 164d4a1cf6dcabfedf81cad3ee2daee56459ee4b Mon Sep 17 00:00:00 2001
From: Jonas Devlieghere <jonas@devlieghere.com>
Date: Sun, 28 Jan 2018 11:05:10 +0000
Subject: [PATCH] [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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323616 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/BinaryFormat/Dwarf.h             |  3 ---
 include/llvm/Support/DJB.h                    | 25 +++++++++++++++++++
 lib/BinaryFormat/Dwarf.cpp                    |  6 -----
 lib/CodeGen/AsmPrinter/DwarfAccelTable.h      |  3 ++-
 lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp |  3 ++-
 lib/Support/CMakeLists.txt                    |  1 +
 lib/Support/DJB.cpp                           | 20 +++++++++++++++
 7 files changed, 50 insertions(+), 11 deletions(-)
 create mode 100644 include/llvm/Support/DJB.h
 create mode 100644 lib/Support/DJB.cpp

diff --git a/include/llvm/BinaryFormat/Dwarf.h b/include/llvm/BinaryFormat/Dwarf.h
index e355b442e35..29df99b5de7 100644
--- a/include/llvm/BinaryFormat/Dwarf.h
+++ b/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
diff --git a/include/llvm/Support/DJB.h b/include/llvm/Support/DJB.h
new file mode 100644
index 00000000000..02e2ce07557
--- /dev/null
+++ b/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
diff --git a/lib/BinaryFormat/Dwarf.cpp b/lib/BinaryFormat/Dwarf.cpp
index 0ec57870f65..169e50e8d14 100644
--- a/lib/BinaryFormat/Dwarf.cpp
+++ b/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;
-}
diff --git a/lib/CodeGen/AsmPrinter/DwarfAccelTable.h b/lib/CodeGen/AsmPrinter/DwarfAccelTable.h
index f56199dc8e7..36373076096 100644
--- a/lib/CodeGen/AsmPrinter/DwarfAccelTable.h
+++ b/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
diff --git a/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp b/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
index ac30f74f346..8bb14876f15 100644
--- a/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
+++ b/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;
diff --git a/lib/Support/CMakeLists.txt b/lib/Support/CMakeLists.txt
index 5723f8fcf5b..d7020336cc9 100644
--- a/lib/Support/CMakeLists.txt
+++ b/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
diff --git a/lib/Support/DJB.cpp b/lib/Support/DJB.cpp
new file mode 100644
index 00000000000..c696f1e6a0b
--- /dev/null
+++ b/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;
+}