Revert of Slim Skia down to just one murmur3 implementation. (https://codereview.chromium.org/376183004/)
Reason for revert:
Valgrind unhappy. skia:2735
Original issue's description:
> Slim Skia down to just one murmur3 implementation.
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/6ac0037b70410ff7d5ce5788bc89314223e1a587
R=reed@google.com, mtklein@chromium.org
TBR=mtklein@chromium.org, reed@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:
Author: mtklein@google.com
Review URL: https://codereview.chromium.org/378413002
diff --git a/bench/FontCacheBench.cpp b/bench/FontCacheBench.cpp
index 697bde6..0e75c9c 100644
--- a/bench/FontCacheBench.cpp
+++ b/bench/FontCacheBench.cpp
@@ -7,7 +7,6 @@
#include "Benchmark.h"
#include "SkCanvas.h"
-#include "SkChecksum.h"
#include "SkFontHost.h"
#include "SkPaint.h"
#include "SkString.h"
@@ -65,12 +64,23 @@
return value ^ (value >> 8);
}
+static uint32_t hasher2(uint32_t h) {
+ h ^= h >> 16;
+ h *= 0x85ebca6b;
+ h ^= h >> 13;
+ h *= 0xc2b2ae35;
+ h ^= h >> 16;
+
+ h ^= (h >> 8);
+ return h;
+}
+
static const struct {
const char* fName;
HasherProc fHasher;
} gRec[] = {
{ "hasher0", hasher0 },
- { "hasher2", SkChecksum::Mix },
+ { "hasher2", hasher2 },
};
#define kMaxHashBits 12
diff --git a/src/core/SkChecksum.h b/src/core/SkChecksum.h
index fe1e958..bf3228f 100644
--- a/src/core/SkChecksum.h
+++ b/src/core/SkChecksum.h
@@ -36,20 +36,6 @@
}
public:
- /**
- * uint32_t -> uint32_t hash, useful for when you're about to trucate this hash but you
- * suspect its low bits aren't well mixed.
- *
- * This is the Murmur3 finalizer.
- */
- static uint32_t Mix(uint32_t hash) {
- hash ^= hash >> 16;
- hash *= 0x85ebca6b;
- hash ^= hash >> 13;
- hash *= 0xc2b2ae35;
- hash ^= hash >> 16;
- return hash;
- }
/**
* Calculate 32-bit Murmur hash (murmur3).
@@ -62,7 +48,7 @@
* @return hash result
*/
static uint32_t Murmur3(const uint32_t* data, size_t bytes, uint32_t seed=0) {
- SkASSERTF(SkIsAlign4(bytes), "Expected 4-byte multiple, got %zu", bytes);
+ SkASSERT(SkIsAlign4(bytes));
const size_t words = bytes/4;
uint32_t hash = seed;
@@ -78,7 +64,12 @@
hash += 0xe6546b64;
}
hash ^= bytes;
- return Mix(hash);
+ hash ^= hash >> 16;
+ hash *= 0x85ebca6b;
+ hash ^= hash >> 13;
+ hash *= 0xc2b2ae35;
+ hash ^= hash >> 16;
+ return hash;
}
/**
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index 8a0e734..64603b4 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -8,7 +8,6 @@
#include "SkImageFilter.h"
#include "SkBitmap.h"
-#include "SkChecksum.h"
#include "SkDevice.h"
#include "SkReadBuffer.h"
#include "SkWriteBuffer.h"
@@ -335,6 +334,31 @@
}
#endif
+static uint32_t compute_hash(const uint32_t* data, int count) {
+ uint32_t hash = 0;
+
+ for (int i = 0; i < count; ++i) {
+ uint32_t k = data[i];
+ k *= 0xcc9e2d51;
+ k = (k << 15) | (k >> 17);
+ k *= 0x1b873593;
+
+ hash ^= k;
+ hash = (hash << 13) | (hash >> 19);
+ hash *= 5;
+ hash += 0xe6546b64;
+ }
+
+ // hash ^= size;
+ hash ^= hash >> 16;
+ hash *= 0x85ebca6b;
+ hash ^= hash >> 13;
+ hash *= 0xc2b2ae35;
+ hash ^= hash >> 16;
+
+ return hash;
+}
+
class CacheImpl : public SkImageFilter::Cache {
public:
explicit CacheImpl(int minChildren) : fMinChildren(minChildren) {
@@ -357,7 +381,7 @@
return v.fKey;
}
static uint32_t Hash(Key key) {
- return SkChecksum::Murmur3(reinterpret_cast<const uint32_t*>(&key), sizeof(Key));
+ return compute_hash(reinterpret_cast<const uint32_t*>(&key), sizeof(Key) / sizeof(uint32_t));
}
};
SkTDynamicHash<Value, Key> fData;
diff --git a/src/core/SkScaledImageCache.cpp b/src/core/SkScaledImageCache.cpp
index 1e7f51d..eda4871 100644
--- a/src/core/SkScaledImageCache.cpp
+++ b/src/core/SkScaledImageCache.cpp
@@ -5,7 +5,6 @@
* found in the LICENSE file.
*/
-#include "SkChecksum.h"
#include "SkScaledImageCache.h"
#include "SkMipMap.h"
#include "SkPixelRef.h"
@@ -30,6 +29,32 @@
return reinterpret_cast<SkScaledImageCache::Rec*>(id);
}
+ // Implemented from en.wikipedia.org/wiki/MurmurHash.
+static uint32_t compute_hash(const uint32_t data[], int count) {
+ uint32_t hash = 0;
+
+ for (int i = 0; i < count; ++i) {
+ uint32_t k = data[i];
+ k *= 0xcc9e2d51;
+ k = (k << 15) | (k >> 17);
+ k *= 0x1b873593;
+
+ hash ^= k;
+ hash = (hash << 13) | (hash >> 19);
+ hash *= 5;
+ hash += 0xe6546b64;
+ }
+
+ // hash ^= size;
+ hash ^= hash >> 16;
+ hash *= 0x85ebca6b;
+ hash ^= hash >> 13;
+ hash *= 0xc2b2ae35;
+ hash ^= hash >> 16;
+
+ return hash;
+}
+
struct SkScaledImageCache::Key {
Key(uint32_t genID,
SkScalar scaleX,
@@ -39,7 +64,7 @@
, fScaleX(scaleX)
, fScaleY(scaleY)
, fBounds(bounds) {
- fHash = SkChecksum::Murmur3(&fGenID, 28);
+ fHash = compute_hash(&fGenID, 7);
}
bool operator<(const Key& other) const {
