Add support for computing SHA1 in LLVM

Provide a class to generate a SHA1 from a sequence of bytes, and
a convenience raw_ostream adaptor.
This will be used to provide a "build-id" by hashing the Module
block when writing bitcode. ThinLTO will use this information for
incremental build.

Reapply r265094 which was reverted in r265102 because it broke
MSVC bots (constexpr is not supported).

http://reviews.llvm.org/D16325

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 265107

2 files changed, 73 insertions, 0 deletions

diff --git a/llvm/unittests/Support/CMakeLists.txt b/llvm/unittests/Support/CMakeLists.txt
index f02d501538b..9a4a1445091 100644
--- a/llvm/unittests/Support/CMakeLists.txt
+++ b/llvm/unittests/Support/CMakeLists.txt
@@ -52,6 +52,7 @@ add_llvm_unittest(SupportTests
   formatted_raw_ostream_test.cpp
   raw_ostream_test.cpp
   raw_pwrite_stream_test.cpp
+  raw_sha1_ostream_test.cpp
   )
 
 # ManagedStatic.cpp uses <pthread>.
diff --git a/llvm/unittests/Support/raw_sha1_ostream_test.cpp b/llvm/unittests/Support/raw_sha1_ostream_test.cpp
new file mode 100644
index 00000000000..ca80cdac49e
--- /dev/null
+++ b/llvm/unittests/Support/raw_sha1_ostream_test.cpp
@@ -0,0 +1,72 @@
+//===- llvm/unittest/Support/raw_ostream_test.cpp - raw_ostream tests -----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/raw_sha1_ostream.h"
+
+#include <string>
+
+using namespace llvm;
+
+static std::string toHex(StringRef Input) {
+  static const char *const LUT = "0123456789ABCDEF";
+  size_t Length = Input.size();
+
+  std::string Output;
+  Output.reserve(2 * Length);
+  for (size_t i = 0; i < Length; ++i) {
+    const unsigned char c = Input[i];
+    Output.push_back(LUT[c >> 4]);
+    Output.push_back(LUT[c & 15]);
+  }
+  return Output;
+}
+
+TEST(raw_sha1_ostreamTest, Basic) {
+  llvm::raw_sha1_ostream Sha1Stream;
+  Sha1Stream << "Hello World!";
+  auto Hash = toHex(Sha1Stream.sha1());
+
+  ASSERT_EQ("2EF7BDE608CE5404E97D5F042F95F89F1C232871", Hash);
+}
+
+// Check that getting the intermediate hash in the middle of the stream does
+// not invalidate the final result.
+TEST(raw_sha1_ostreamTest, Intermediate) {
+  llvm::raw_sha1_ostream Sha1Stream;
+  Sha1Stream << "Hello";
+  auto Hash = toHex(Sha1Stream.sha1());
+
+  ASSERT_EQ("F7FF9E8B7BB2E09B70935A5D785E0CC5D9D0ABF0", Hash);
+  Sha1Stream << " World!";
+  Hash = toHex(Sha1Stream.sha1());
+
+  // Compute the non-split hash separately as a reference.
+  llvm::raw_sha1_ostream NonSplitSha1Stream;
+  NonSplitSha1Stream << "Hello World!";
+  auto NonSplitHash = toHex(NonSplitSha1Stream.sha1());
+
+  ASSERT_EQ(NonSplitHash, Hash);
+}
+
+TEST(raw_sha1_ostreamTest, Reset) {
+  llvm::raw_sha1_ostream Sha1Stream;
+  Sha1Stream << "Hello";
+  auto Hash = toHex(Sha1Stream.sha1());
+
+  ASSERT_EQ("F7FF9E8B7BB2E09B70935A5D785E0CC5D9D0ABF0", Hash);
+
+  Sha1Stream.resetHash();
+  Sha1Stream << " World!";
+  Hash = toHex(Sha1Stream.sha1());
+
+  ASSERT_EQ("7447F2A5A42185C8CF91E632789C431830B59067", Hash);
+}