Pull google/benchmark library to the LLVM tree

This patch pulls google/benchmark v1.4.1 into the LLVM tree so that any
project could use it for benchmark generation. A dummy benchmark is
added to `llvm/benchmarks/DummyYAML.cpp` to validate the correctness of
the build process.

The current version does not utilize LLVM LNT and LLVM CMake
infrastructure, but that might be sufficient for most users. Two
introduced CMake variables:

* `LLVM_INCLUDE_BENCHMARKS` (`ON` by default) generates benchmark
  targets
* `LLVM_BUILD_BENCHMARKS` (`OFF` by default) adds generated
  benchmark targets to the list of default LLVM targets (i.e. if `ON`
  benchmarks will be built upon standard build invocation, e.g. `ninja` or
  `make` with no specific targets)

List of modifications:

* `BENCHMARK_ENABLE_TESTING` is disabled
* `BENCHMARK_ENABLE_EXCEPTIONS` is disabled
* `BENCHMARK_ENABLE_INSTALL` is disabled
* `BENCHMARK_ENABLE_GTEST_TESTS` is disabled
* `BENCHMARK_DOWNLOAD_DEPENDENCIES` is disabled

Original discussion can be found here:
http://lists.llvm.org/pipermail/llvm-dev/2018-August/125023.html

Reviewed by: dberris, lebedev.ri

Subscribers: ilya-biryukov, ioeric, EricWF, lebedev.ri, srhines,
dschuff, mgorny, krytarowski, fedor.sergeev, mgrang, jfb, llvm-commits

Differential Revision: https://reviews.llvm.org/D50894

llvm-svn: 340809

1 files changed, 47 insertions, 0 deletions

diff --git a/llvm/utils/benchmark/src/benchmark_api_internal.h b/llvm/utils/benchmark/src/benchmark_api_internal.h
new file mode 100644
index 00000000000..dd7a3ffe8cb
--- /dev/null
+++ b/llvm/utils/benchmark/src/benchmark_api_internal.h
@@ -0,0 +1,47 @@
+#ifndef BENCHMARK_API_INTERNAL_H
+#define BENCHMARK_API_INTERNAL_H
+
+#include "benchmark/benchmark.h"
+
+#include <cmath>
+#include <iosfwd>
+#include <limits>
+#include <string>
+#include <vector>
+
+namespace benchmark {
+namespace internal {
+
+// Information kept per benchmark we may want to run
+struct Benchmark::Instance {
+  std::string name;
+  Benchmark* benchmark;
+  ReportMode report_mode;
+  std::vector<int64_t> arg;
+  TimeUnit time_unit;
+  int range_multiplier;
+  bool use_real_time;
+  bool use_manual_time;
+  BigO complexity;
+  BigOFunc* complexity_lambda;
+  UserCounters counters;
+  const std::vector<Statistics>* statistics;
+  bool last_benchmark_instance;
+  int repetitions;
+  double min_time;
+  size_t iterations;
+  int threads;  // Number of concurrent threads to us
+};
+
+bool FindBenchmarksInternal(const std::string& re,
+                            std::vector<Benchmark::Instance>* benchmarks,
+                            std::ostream* Err);
+
+bool IsZero(double n);
+
+ConsoleReporter::OutputOptions GetOutputOptions(bool force_no_color = false);
+
+}  // end namespace internal
+}  // end namespace benchmark
+
+#endif  // BENCHMARK_API_INTERNAL_H