This fixes building for Windows on ARM, with MinGW headers.
(Building for Windows on ARM with Windows SDK still is unsupported
by the benchmark library.)

Differential Revision: https://reviews.llvm.org/D52262

llvm-svn: 342549

This was cherry-picked in SVN r342450.

llvm-svn: 342506

This patch applies upstream commit:
https://github.com/google/benchmark/commit/f0901417c89d123474e6b91365029cfe32cf89dc

Tim Northover pointed out that benchmark build might be broken on 32-bit
macOS. This commit by Roman Lebedev (lebedev.ri) resolves the issue.

Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D51677

llvm-svn: 341469

llvm-svn: 340817

ompiling benchmark library (introduced in D50894) with the latest
bootstrapped Clang produces a lot of warnings, this issue was addressed
in the upstream patch I pushed earlier.

Upstream patch:
https://github.com/google/benchmark/commit/f85304e4e3a0e4e1bf15b91720df4a19e90b589f

`README.LLVM` notes were updated to reflect the latest changes.

Reviewed by: lebedev.ri

Differential Revision: https://reviews.llvm.org/D51342

llvm-svn: 340811

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