platform_bionic/linker/linker_gnu_hash.h
Ryan Prichard 129f7a1d8e 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
2020-01-13 13:29:25 -08:00

62 lines
2.2 KiB
C++

/*
* 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.
*/
#pragma once
#include <stdint.h>
#include <utility>
#if defined(__arm__) || defined(__aarch64__)
#define USE_GNU_HASH_NEON 1
#else
#define USE_GNU_HASH_NEON 0
#endif
#if USE_GNU_HASH_NEON
#include "arch/arm_neon/linker_gnu_hash_neon.h"
#endif
__attribute__((unused))
static std::pair<uint32_t, uint32_t> calculate_gnu_hash_simple(const char* name) {
uint32_t h = 5381;
const uint8_t* name_bytes = reinterpret_cast<const uint8_t*>(name);
#pragma unroll 8
while (*name_bytes != 0) {
h += (h << 5) + *name_bytes++; // h*33 + c = h + h * 32 + c = h + h << 5 + c
}
return { h, reinterpret_cast<const char*>(name_bytes) - name };
}
static inline std::pair<uint32_t, uint32_t> calculate_gnu_hash(const char* name) {
#if USE_GNU_HASH_NEON
return calculate_gnu_hash_neon(name);
#else
return calculate_gnu_hash_simple(name);
#endif
}