[bazel] Build libpfm as a dependency to allow collection of perf counters (#1408)

* Build libpfm as a dependency to allow collection of perf counters

This commit builds libpfm using rules_foreign_cc and lets the default
build of the benchmark library support perf counter collection without
needing additional work from users.

Tested with a custom target:

```
bazel run \
        --override_repository=com_github_google_benchmark=/home/raghu/benchmark \
        -c opt :test-bench -- "--benchmark_perf_counters=INSTRUCTIONS,CYCLES"
Using profile: local

<snip>

----------------------------------------------------------------------
Benchmark            Time             CPU   Iterations UserCounters...
----------------------------------------------------------------------
BM_Test      0.279 ns        0.279 ns   1000000000 CYCLES=1.00888 INSTRUCTIONS=2

```

Signed-off-by: Raghu Raja <raghu@enfabrica.net>

* Adding myself to the CONTRIBUTORS file per CLA guidance

Enfabrica has already signed a corporate CLA.

Signed-off-by: Raghu Raja <raghu@enfabrica.net>

Signed-off-by: Raghu Raja <raghu@enfabrica.net>

AUTHORS

@@ -50,6 +50,7 @@ Norman Heino <norman.heino@gmail.com>
 Oleksandr Sochka <sasha.sochka@gmail.com>
 Ori Livneh <ori.livneh@gmail.com>
 Paul Redmond <paul.redmond@gmail.com>
+Raghu Raja <raghu@enfabrica.net>
 Radoslav Yovchev <radoslav.tm@gmail.com>
 Rainer Orth <ro@cebitec.uni-bielefeld.de>
 Roman Lebedev <lebedev.ri@gmail.com>

BUILD.bazel

@@ -18,6 +18,14 @@ config_setting(
     visibility = [":__subpackages__"],
 )
 
+config_setting(
+    name = "perfcounters",
+    define_values = {
+        "pfm": "1",
+    },
+    visibility = [":__subpackages__"],
+)
+
 cc_library(
     name = "benchmark",
     srcs = glob(
@@ -41,7 +49,16 @@ cc_library(
     # Using `defines` (i.e. not `local_defines`) means that no
     # dependent rules need to bother about defining the macro.
     linkstatic = True,
-    defines = ["BENCHMARK_STATIC_DEFINE"],
+    defines = [
+        "BENCHMARK_STATIC_DEFINE",
+    ] + select({
+        ":perfcounters": ["HAVE_LIBPFM"],
+        "//conditions:default": [],
+    }),
+    deps = select({
+        ":perfcounters": ["@libpfm//:libpfm"],
+        "//conditions:default": [],
+    }),
 )
 
 cc_library(

CONTRIBUTORS

@@ -74,6 +74,7 @@ Paul Redmond <paul.redmond@gmail.com>
 Pierre Phaneuf <pphaneuf@google.com>
 Radoslav Yovchev <radoslav.tm@gmail.com>
 Rainer Orth <ro@cebitec.uni-bielefeld.de>
+Raghu Raja <raghu@enfabrica.net>
 Raul Marin <rmrodriguez@cartodb.com>
 Ray Glover <ray.glover@uk.ibm.com>
 Robert Guo <robert.guo@mongodb.com>

WORKSPACE

@@ -3,6 +3,27 @@ workspace(name = "com_github_google_benchmark")
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 load("@bazel_tools//tools/build_defs/repo:git.bzl", "git_repository")
 
+
+http_archive(
+    name = "bazel_skylib",
+    urls = [
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.2.1/bazel-skylib-1.2.1.tar.gz",
+        "https://github.com/bazelbuild/bazel-skylib/releases/download/1.2.1/bazel-skylib-1.2.1.tar.gz",
+    ],
+    sha256 = "f7be3474d42aae265405a592bb7da8e171919d74c16f082a5457840f06054728",
+)
+
+# https://github.com/bazelbuild/rules_foreign_cc/
+http_archive(
+    name = "rules_foreign_cc",
+    sha256 = "bcd0c5f46a49b85b384906daae41d277b3dc0ff27c7c752cc51e43048a58ec83",
+    strip_prefix = "rules_foreign_cc-0.7.1",
+    url = "https://github.com/bazelbuild/rules_foreign_cc/archive/0.7.1.tar.gz",
+)
+
+load("@rules_foreign_cc//foreign_cc:repositories.bzl", "rules_foreign_cc_dependencies")
+rules_foreign_cc_dependencies()
+
 http_archive(
     name = "com_google_absl",
     sha256 = "f41868f7a938605c92936230081175d1eae87f6ea2c248f41077c8f88316f111",
@@ -16,6 +37,16 @@ git_repository(
     tag = "release-1.11.0",
 )
 
+# Downloaded from v4.9.0 tag at https://sourceforge.net/p/perfmon2/libpfm4/ref/master/tags/
+http_archive(
+    name = "libpfm",
+    build_file = "//tools:libpfm.BUILD.bazel",
+    sha256 = "5da5f8872bde14b3634c9688d980f68bda28b510268723cc12973eedbab9fecc",
+    type = "tar.gz",
+    strip_prefix = "libpfm-4.11.0",
+    urls = ["https://sourceforge.net/projects/perfmon2/files/libpfm4/libpfm-4.11.0.tar.gz/download"],
+)
+
 http_archive(
     name = "pybind11",
     build_file = "@//bindings/python:pybind11.BUILD",

docs/perf_counters.md

@@ -12,16 +12,17 @@ This feature is available if:
 * The benchmark is run on an architecture featuring a Performance Monitoring
   Unit (PMU),
 * The benchmark is compiled with support for collecting counters. Currently,
-  this requires [libpfm](http://perfmon2.sourceforge.net/) be available at build
+  this requires [libpfm](http://perfmon2.sourceforge.net/), which is built as a
-  time
+  dependency via Bazel.
 
 The feature does not require modifying benchmark code. Counter collection is
 handled at the boundaries where timer collection is also handled. 
 
 To opt-in:
-
+* If using a Bazel build, add `--define pfm=1` to your buid flags
-*  Install `libpfm4-dev`, e.g. `apt-get install libpfm4-dev`.
+* If using CMake:
-*  Enable the cmake flag BENCHMARK_ENABLE_LIBPFM.
+  * Install `libpfm4-dev`, e.g. `apt-get install libpfm4-dev`.
+  * Enable the CMake flag `BENCHMARK_ENABLE_LIBPFM` in `CMakeLists.txt`.
 
 To use, pass a comma-separated list of counter names through the
 `--benchmark_perf_counters` flag. The names are decoded through libpfm - meaning,
@@ -31,4 +32,4 @@ mapped by libpfm to platform-specifics - see libpfm
 
 The counter values are reported back through the [User Counters](../README.md#custom-counters)
 mechanism, meaning, they are available in all the formats (e.g. JSON) supported
-by User Counters.
+by User Counters.

tools/libpfm.BUILD.bazel

@@ -0,0 +1,21 @@
+# Build rule for libpfm, which is required to collect performance counters for
+# BENCHMARK_ENABLE_LIBPFM builds.
+
+load("@rules_foreign_cc//foreign_cc:defs.bzl", "make")
+
+filegroup(
+    name = "pfm_srcs",
+    srcs = glob(["**"]),
+)
+
+make(
+    name = "libpfm",
+    lib_source = ":pfm_srcs",
+    lib_name = "libpfm",
+    copts = [
+        "-Wno-format-truncation",
+    ],
+    visibility = [
+        "//visibility:public",
+    ],
+)