Imported Upstream version 6.0.0.172

Former-commit-id: f3cc9b82f3e5bd8f0fd3ebc098f789556b44e9cd

external/llvm/lib/Support/Hashing.cpp

@@ -0,0 +1,29 @@
+//===-------------- lib/Support/Hashing.cpp -------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides implementation bits for the LLVM common hashing
+// infrastructure. Documentation and most of the other information is in the
+// header file.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/Hashing.h"
+
+using namespace llvm;
+
+// Provide a definition and static initializer for the fixed seed. This
+// initializer should always be zero to ensure its value can never appear to be
+// non-zero, even during dynamic initialization.
+size_t llvm::hashing::detail::fixed_seed_override = 0;
+
+// Implement the function for forced setting of the fixed seed.
+// FIXME: Use atomic operations here so that there is no data race.
+void llvm::set_fixed_execution_hash_seed(size_t fixed_value) {
+  hashing::detail::fixed_seed_override = fixed_value;
+}