use bazel to build microbenchmarks in bm_build.py

tools/profiling/microbenchmarks/bm_diff/bm_build.py

@@ -32,11 +32,13 @@ def _args():
                       choices=bm_constants._AVAILABLE_BENCHMARK_TESTS,
                       default=bm_constants._AVAILABLE_BENCHMARK_TESTS,
                       help='Which benchmarks to build')
-    argp.add_argument('-j',
+    argp.add_argument(
+        '-j',
         '--jobs',
         type=int,
         default=multiprocessing.cpu_count(),
-                      help='How many CPUs to dedicate to this task')
+        help=
+        'Deprecated. Bazel chooses number of CPUs to build with automatically.')
     argp.add_argument(
         '-n',
         '--name',
@@ -52,26 +54,33 @@ def _args():
     return args
 
 
-def _make_cmd(cfg, benchmarks, jobs):
-    return ['make'] + benchmarks + ['CONFIG=%s' % cfg, '-j', '%d' % jobs]
+def _build_cmd(cfg, benchmarks):
+    bazel_targets = [
+        '//test/cpp/microbenchmarks:%s' % benchmark for benchmark in benchmarks
+    ]
+    # --dynamic_mode=off makes sure that we get a monolithic binary that can be safely
+    # moved outside of the bazel-bin directory
+    return ['tools/bazel', 'build',
+            '--config=%s' % cfg, '--dynamic_mode=off'] + bazel_targets
+
+
+def _build_config_and_copy(cfg, benchmarks, dest_dir):
+    """Build given config and copy resulting binaries to dest_dir/CONFIG"""
+    subprocess.check_call(_build_cmd(cfg, benchmarks))
+    cfg_dir = dest_dir + '/%s' % cfg
+    os.makedirs(cfg_dir)
+    subprocess.check_call(['cp'] + [
+        'bazel-bin/test/cpp/microbenchmarks/%s' % benchmark
+        for benchmark in benchmarks
+    ] + [cfg_dir])
 
 
 def build(name, benchmarks, jobs, counters):
-    shutil.rmtree('bm_diff_%s' % name, ignore_errors=True)
-    subprocess.check_call(['git', 'submodule', 'update'])
-    try:
-        subprocess.check_call(_make_cmd('opt', benchmarks, jobs))
-        if counters:
-            subprocess.check_call(_make_cmd('counters', benchmarks, jobs))
-    except subprocess.CalledProcessError, e:
-        subprocess.check_call(['make', 'clean'])
-        subprocess.check_call(_make_cmd('opt', benchmarks, jobs))
+    dest_dir = 'bm_diff_%s' % name
+    shutil.rmtree(dest_dir, ignore_errors=True)
+    _build_config_and_copy('opt', benchmarks, dest_dir)
     if counters:
-            subprocess.check_call(_make_cmd('counters', benchmarks, jobs))
-    os.rename(
-        'bins',
-        'bm_diff_%s' % name,
-    )
+        _build_config_and_copy('counters', benchmarks, dest_dir)
 
 
 if __name__ == '__main__':