Hashing.h - utilities for hashing various data types.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150890 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 47 insertions, 0 deletions

diff --git a/lib/Support/CMakeLists.txt b/lib/Support/CMakeLists.txt
index 6cec47df67..0b69238274 100644
--- a/lib/Support/CMakeLists.txt
+++ b/lib/Support/CMakeLists.txt
@@ -26,6 +26,7 @@ add_llvm_library(LLVMSupport
   FoldingSet.cpp
   FormattedStream.cpp
   GraphWriter.cpp
+  Hashing.cpp
   IntEqClasses.cpp
   IntervalMap.cpp
   IntrusiveRefCntPtr.cpp
diff --git a/lib/Support/Hashing.cpp b/lib/Support/Hashing.cpp
new file mode 100644
index 0000000000..89b84530af
--- /dev/null
+++ b/lib/Support/Hashing.cpp
@@ -0,0 +1,46 @@
+//===-- llvm/ADT/Hashing.cpp - Utilities for hashing ------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/Hashing.h"
+
+namespace llvm {
+
+// Add a possibly unaligned sequence of bytes.
+void GeneralHash::addUnaligned(const uint8_t *I, const uint8_t *E) {
+  ptrdiff_t Length = E - I;
+  if (uintptr_t(I) & 3 == 0) {
+    while (Length > 3) {
+      mix(*reinterpret_cast<const uint32_t *>(I));
+      I += 4;
+      Length -= 4;
+    }
+  } else {
+    while (Length > 3) {
+      mix(
+        uint32_t(I[0]) +
+        (uint32_t(I[1]) << 8) +
+        (uint32_t(I[2]) << 16) +
+        (uint32_t(I[3]) << 24));
+      I += 4;
+      Length -= 4;
+    }
+  }
+
+  if (Length & 3) {
+    uint32_t Data = 0;
+    switch (Length & 3) {
+      case 3: Data |= uint32_t(I[2]) << 16;   // fall through
+      case 2: Data |= uint32_t(I[1]) << 8;    // fall through
+      case 1: Data |= uint32_t(I[0]); break;
+    }
+    mix(Data);
+  }
+}
+
+}