Add a linker relocation benchmark

The benchmark creates a set of DSOs that mimic the work involved in
loading the current version of libandroid_servers.so. The synthetic
benchmark has roughly the same number of libraries with roughly the same
relocations.

Currently, on a local aosp_walleye build that includes recent performance
improvements (including the Neon-based CL
I3983bca1dddc9241bb70290ad3651d895f046660), using the "performance"
governor, the benchmark reports these scores:

$ adb shell taskset 10 \
  /data/benchmarktest64/linker-reloc-bench/linker-reloc-bench \
  --benchmark_repetitions=20 --benchmark_display_aggregates_only=true
...
--------------------------------------------------------------------------------
Benchmark                                      Time             CPU   Iterations
--------------------------------------------------------------------------------
BM_linker_relocation/real_time_mean        70048 us          465 us           20
BM_linker_relocation/real_time_median      70091 us          466 us           20
BM_linker_relocation/real_time_stddev        329 us         8.29 us           20

$ adb shell taskset 10 \
  /data/benchmarktest/linker-reloc-bench/linker-reloc-bench \
  --benchmark_repetitions=20 --benchmark_display_aggregates_only=true
...
--------------------------------------------------------------------------------
Benchmark                                      Time             CPU   Iterations
--------------------------------------------------------------------------------
BM_linker_relocation/real_time_mean        83051 us          462 us           20
BM_linker_relocation/real_time_median      83069 us          464 us           20
BM_linker_relocation/real_time_stddev        184 us         8.91 us           20

Test: manual
Bug: none
Change-Id: I6dac66978f8666f95c76387093bda6be0151bfce
diff --git a/benchmarks/linker_relocation/Android.bp b/benchmarks/linker_relocation/Android.bp
new file mode 100644
index 0000000..dfb20ba
--- /dev/null
+++ b/benchmarks/linker_relocation/Android.bp
@@ -0,0 +1,82 @@
+// Copyright (C) 2019 The Android Open Source Project
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//  * Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+//  * Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in
+//    the documentation and/or other materials provided with the
+//    distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+// OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+// AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+// SUCH DAMAGE.
+
+cc_library_headers {
+    name: "linker_reloc_bench_headers",
+    defaults: ["bionic_spawn_benchmark_targets"],
+    export_include_dirs: ["include"],
+}
+
+// TODO: This benchmark doesn't work with TradeFed/atest because it doesn't copy its test libraries
+// into the testcases/linker_reloc_bench directory. The obvious way to do that is to list each
+// library in the "data" property, but that doesn't work, because each library is listed as having a
+// "link:shared" variant (as opposed to "link:static"), whereas the cc_benchmark has no
+// "link:(shared/static)" variation. It appears that Soong needs to be fixed to make this benchmark
+// work with TradeFed/atest.
+
+cc_benchmark {
+    name: "linker-reloc-bench",
+
+    defaults: [
+        "bionic_spawn_benchmark_targets",
+        "linker_reloc_bench_all_libs",
+    ],
+
+    data: [":linker_reloc_bench_main"],
+    srcs: ["linker_reloc_bench.cpp"],
+
+    static_libs: [
+        "libbase",
+        "libbionic_spawn_benchmark",
+    ],
+}
+
+cc_defaults {
+    name: "linker_reloc_bench_binary",
+    defaults: ["bionic_spawn_benchmark_targets"],
+    header_libs: ["linker_reloc_bench_headers"],
+    stl: "none",
+    gtest: false,
+
+    compile_multilib: "both",
+    multilib: {
+        lib32: { suffix: "32" },
+        lib64: { suffix: "64" },
+    },
+}
+
+cc_defaults {
+    name: "linker_reloc_bench_library",
+    defaults: ["bionic_spawn_benchmark_targets"],
+    header_libs: ["linker_reloc_bench_headers"],
+    stl: "none",
+    gtest: false,
+    relative_install_path: "linker-reloc-bench",
+
+    static: {
+        enabled: false,
+    },
+}