skia2/tests/ChecksumTest.cpp
Mike Klein 5334e8976d Revert "restore murmur3 for older iOS devices"
This reverts commit 3c161467f0.

Reason for revert: need to keep iOS simulator (Build-Mac-Clang-x64-Release-iOS) in mind

Original change's description:
> restore murmur3 for older iOS devices
>
> For reference, the relative costs are roughly,
>    - our hash with CRC32c instructions    1x
>    - Murmur3                             11x
>    - our hash with CRC32c fallback       23x
>
> So this should be a ~2x speedup for those
> older iOS devices not using an arm64e slice.
>
> Bug: skia:11001
> Cq-Include-Trybots: luci.skia.skia.primary:Test-iOS-Clang-iPadPro-GPU-PowerVRGT7800-arm64-Debug-All,Test-iOS-Clang-iPhone11-GPU-AppleA13-arm64-Debug-All,Test-iOS-Clang-iPhone6-GPU-PowerVRGX6450-arm64-Debug-All,Test-iOS-Clang-iPhone7-GPU-PowerVRGT7600-arm64-Debug-All,Test-iOS-Clang-iPhone8-GPU-AppleA11-arm64-Debug-All
> Change-Id: Ib56195ddc0c522380d263d56e767331d9f635728
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/340178
> Commit-Queue: Mike Klein <mtklein@google.com>
> Reviewed-by: Brian Osman <brianosman@google.com>

TBR=mtklein@google.com,brianosman@google.com

Change-Id: I0e3b23e63c33910e482031d7475feb624bd6e1f6
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:11001
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/340396
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
2020-12-02 22:39:01 +00:00

91 lines
3.5 KiB
C++

/*
* Copyright 2012 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "include/core/SkTypes.h"
#include "include/private/SkChecksum.h"
#include "include/utils/SkRandom.h"
#include "src/core/SkOpts.h"
#include "tests/Test.h"
DEF_TEST(Checksum, r) {
// Put 128 random bytes into two identical buffers. Any multiple of 4 will do.
const size_t kBytes = SkAlign4(128);
SkRandom rand;
uint32_t data[kBytes/4], tweaked[kBytes/4];
for (size_t i = 0; i < SK_ARRAY_COUNT(tweaked); ++i) {
data[i] = tweaked[i] = rand.nextU();
}
// Hash of nullptr is always 0.
REPORTER_ASSERT(r, SkOpts::hash(nullptr, 0) == 0);
const uint32_t hash = SkOpts::hash(data, kBytes);
// Should be deterministic.
REPORTER_ASSERT(r, hash == SkOpts::hash(data, kBytes));
// Changing any single element should change the hash.
for (size_t j = 0; j < SK_ARRAY_COUNT(tweaked); ++j) {
const uint32_t saved = tweaked[j];
tweaked[j] = rand.nextU();
const uint32_t tweakedHash = SkOpts::hash(tweaked, kBytes);
REPORTER_ASSERT(r, tweakedHash != hash);
REPORTER_ASSERT(r, tweakedHash == SkOpts::hash(tweaked, kBytes));
tweaked[j] = saved;
}
}
DEF_TEST(GoodHash, r) {
// 4 bytes --> hits SkChecksum::Mix fast path.
REPORTER_ASSERT(r, SkGoodHash()(( int32_t)4) == 614249093);
REPORTER_ASSERT(r, SkGoodHash()((uint32_t)4) == 614249093);
}
DEF_TEST(ChecksumCollisions, r) {
// We noticed a few workloads that would cause hash collisions due to the way
// our optimized hashes split into three concurrent hashes and merge those hashes together.
//
// One of these two workloads ought to cause an unintentional hash collision on very similar
// data in those old algorithms, the float version on 32-bit x86 and double elsewhere.
{
float a[9] = { 0, 1, 2,
3, 4, 5,
6, 7, 8, };
float b[9] = { 1, 2, 0,
4, 5, 3,
7, 8, 6, };
REPORTER_ASSERT(r, SkOpts::hash(a, sizeof(a)) != SkOpts::hash(b, sizeof(b)));
}
{
double a[9] = { 0, 1, 2,
3, 4, 5,
6, 7, 8, };
double b[9] = { 1, 2, 0,
4, 5, 3,
7, 8, 6, };
REPORTER_ASSERT(r, SkOpts::hash(a, sizeof(a)) != SkOpts::hash(b, sizeof(b)));
}
}
DEF_TEST(ChecksumConsistent, r) {
// We've decided to make SkOpts::hash() always return consistent results, so spot check a few:
uint8_t bytes[256];
for (int i = 0; i < 256; i++) {
bytes[i] = i;
}
REPORTER_ASSERT(r, SkOpts::hash(bytes, 0) == 0x00000000, "%08x", SkOpts::hash(bytes, 0));
REPORTER_ASSERT(r, SkOpts::hash(bytes, 1) == 0x00000000, "%08x", SkOpts::hash(bytes, 1));
REPORTER_ASSERT(r, SkOpts::hash(bytes, 2) == 0xf26b8303, "%08x", SkOpts::hash(bytes, 2));
REPORTER_ASSERT(r, SkOpts::hash(bytes, 7) == 0x18678721, "%08x", SkOpts::hash(bytes, 7));
REPORTER_ASSERT(r, SkOpts::hash(bytes, 32) == 0x2d3617af, "%08x", SkOpts::hash(bytes, 32));
REPORTER_ASSERT(r, SkOpts::hash(bytes, 63) == 0xd482f6b1, "%08x", SkOpts::hash(bytes, 63));
REPORTER_ASSERT(r, SkOpts::hash(bytes, 64) == 0x2e5a06a9, "%08x", SkOpts::hash(bytes, 64));
REPORTER_ASSERT(r, SkOpts::hash(bytes, 99) == 0x5214485b, "%08x", SkOpts::hash(bytes, 99));
REPORTER_ASSERT(r, SkOpts::hash(bytes,255) == 0xce206bd3, "%08x", SkOpts::hash(bytes,255));
}