Neon-optimized version of the GNU symbol calculation

On 64-bit walleye, improves the linker relocation benchmark from 71.9ms to
70.7ms (1.7% of the run-time).

On a 32-bit device, it improves the linker relocation benchmark from
205.5ms to 201.2ms (2.1% of the run-time).

$ adb shell taskset 10 /data/benchmarktest64/linker-benchmarks/linker-benchmarks --benchmark_repetitions=100 --benchmark_display_aggregates_only
--------------------------------------------------------------------
Benchmark                          Time             CPU   Iterations
--------------------------------------------------------------------
BM_gnu_hash_simple_mean        15232 ns        15212 ns          100
BM_gnu_hash_simple_median      15176 ns        15159 ns          100
BM_gnu_hash_simple_stddev        111 ns          110 ns          100
BM_gnu_hash_neon_mean          10265 ns        10252 ns          100
BM_gnu_hash_neon_median        10261 ns        10249 ns          100
BM_gnu_hash_neon_stddev         28.1 ns         23.9 ns          100

Bug: none
Test: linker-unit-tests
Test: linker-benchmarks
Change-Id: I3983bca1dddc9241bb70290ad3651d895f046660

1 files changed, 59 insertions, 0 deletions

diff --git a/linker/linker_gnu_hash_test.cpp b/linker/linker_gnu_hash_test.cpp
new file mode 100644
index 000000000..a289749f6
--- /dev/null
+++ b/linker/linker_gnu_hash_test.cpp
@@ -0,0 +1,59 @@
+/*
+ * 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.
+ */
+
+#include <gtest/gtest.h>
+
+#include "linker_gnu_hash.h"
+
+TEST(linker_gnu_hash, compare_neon_to_simple) {
+#if USE_GNU_HASH_NEON
+  auto check_input = [&](const char* name) {
+    auto expected = calculate_gnu_hash_simple(name);
+    auto actual = calculate_gnu_hash_neon(name);
+    EXPECT_EQ(expected.first, actual.first) << name;
+    EXPECT_EQ(expected.second, actual.second) << name;
+  };
+
+  __attribute__((aligned(8))) const char test1[] = "abcdefghijklmnop\0qrstuvwxyz";
+  for (size_t i = 0; i < sizeof(test1) - 1; ++i) {
+    check_input(&test1[i]);
+  }
+
+  __attribute__((aligned(8))) const char test2[] = "abcdefghijklmnopqrs\0tuvwxyz";
+  for (size_t i = 0; i < sizeof(test2) - 1; ++i) {
+    check_input(&test2[i]);
+  }
+
+  __attribute__((aligned(8))) const char test3[] = "abcdefghijklmnopqrstuv\0wxyz";
+  for (size_t i = 0; i < sizeof(test3) - 1; ++i) {
+    check_input(&test3[i]);
+  }
+#else
+  GTEST_SKIP() << "This test is only implemented on arm/arm64";
+#endif
+}