Slim Skia down to just one murmur3 implementation.
BUG=skia:
Committed: https://skia.googlesource.com/skia/+/6ac0037b70410ff7d5ce5788bc89314223e1a587
Committed: https://skia.googlesource.com/skia/+/67a3271f0de9ccc32d559b042b862528272047cc
Committed: https://skia.googlesource.com/skia/+/53d435990bdb4d14df78013da45a9364d0287ebe
CQ_EXTRA_TRYBOTS=tryserver.skia:Perf-Mac10.6-MacMini4.1-GeForce320M-x86_64-Release-Trybot
R=reed@google.com, mtklein@google.com
Author: mtklein@chromium.org
Review URL: https://codereview.chromium.org/376183004
diff --git a/src/core/SkChecksum.h b/src/core/SkChecksum.h
index fe1e958..9f2ebf4 100644
--- a/src/core/SkChecksum.h
+++ b/src/core/SkChecksum.h
@@ -62,12 +62,18 @@
* @return hash result
*/
static uint32_t Murmur3(const uint32_t* data, size_t bytes, uint32_t seed=0) {
+ // Use may_alias to remind the compiler we're intentionally violating strict aliasing,
+ // and so not to apply strict-aliasing-based optimizations.
+ typedef uint32_t SK_ATTRIBUTE(may_alias) aliased_uint32_t;
+ const aliased_uint32_t* safe_data = (const aliased_uint32_t*)data;
+
SkASSERTF(SkIsAlign4(bytes), "Expected 4-byte multiple, got %zu", bytes);
const size_t words = bytes/4;
+
uint32_t hash = seed;
for (size_t i = 0; i < words; i++) {
- uint32_t k = data[i];
+ uint32_t k = safe_data[i];
k *= 0xcc9e2d51;
k = (k << 15) | (k >> 17);
k *= 0x1b873593;
@@ -95,6 +101,11 @@
* @return checksum result
*/
static uint32_t Compute(const uint32_t* data, size_t size) {
+ // Use may_alias to remind the compiler we're intentionally violating strict aliasing,
+ // and so not to apply strict-aliasing-based optimizations.
+ typedef uint32_t SK_ATTRIBUTE(may_alias) aliased_uint32_t;
+ const aliased_uint32_t* safe_data = (const aliased_uint32_t*)data;
+
SkASSERT(SkIsAlign4(size));
/*
@@ -104,7 +115,7 @@
* sizeof()).
*/
uintptr_t result = 0;
- const uintptr_t* ptr = reinterpret_cast<const uintptr_t*>(data);
+ const uintptr_t* ptr = reinterpret_cast<const uintptr_t*>(safe_data);
/*
* count the number of quad element chunks. This takes into account
@@ -120,10 +131,10 @@
}
size &= ((sizeof(uintptr_t) << 2) - 1);
- data = reinterpret_cast<const uint32_t*>(ptr);
- const uint32_t* stop = data + (size >> 2);
- while (data < stop) {
- result = Mash(result, *data++);
+ safe_data = reinterpret_cast<const aliased_uint32_t*>(ptr);
+ const aliased_uint32_t* stop = safe_data + (size >> 2);
+ while (safe_data < stop) {
+ result = Mash(result, *safe_data++);
}
/*
diff --git a/src/core/SkImageFilter.cpp b/src/core/SkImageFilter.cpp
index 64603b4..8a0e734 100644
--- a/src/core/SkImageFilter.cpp
+++ b/src/core/SkImageFilter.cpp
@@ -8,6 +8,7 @@
#include "SkImageFilter.h"
#include "SkBitmap.h"
+#include "SkChecksum.h"
#include "SkDevice.h"
#include "SkReadBuffer.h"
#include "SkWriteBuffer.h"
@@ -334,31 +335,6 @@
}
#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) {
@@ -381,7 +357,7 @@
return v.fKey;
}
static uint32_t Hash(Key key) {
- return compute_hash(reinterpret_cast<const uint32_t*>(&key), sizeof(Key) / sizeof(uint32_t));
+ return SkChecksum::Murmur3(reinterpret_cast<const uint32_t*>(&key), sizeof(Key));
}
};
SkTDynamicHash<Value, Key> fData;
