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added SizeMap::MaybeSizeClass

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Because it allows us to first check for smaller sizes, which is most
likely.
This commit is contained in:
Aliaksey Kandratsenka 2015-10-03 18:47:14 -07:00 committed by Aliaksey Kandratsenka
parent 436e1dea43
commit 10f7e20716
1 changed files with 25 additions and 4 deletions
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29
src/common.h
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@ -194,15 +194,23 @@ class SizeMap {
((kMaxSize + 127 + (120 << 7)) >> 7) + 1;
unsigned char class_array_[kClassArraySize];
static inline size_t SmallSizeClass(size_t s) {
return (static_cast<uint32_t>(s) + 7) >> 3;
}
static inline size_t LargeSizeClass(size_t s) {
return (static_cast<uint32_t>(s) + 127 + (120 << 7)) >> 7;
}
// Compute index of the class_array[] entry for a given size
static inline size_t ClassIndex(int s) {
static inline size_t ClassIndex(size_t s) {
// Use unsigned arithmetic to avoid unnecessary sign extensions.
ASSERT(0 <= s);
ASSERT(s <= kMaxSize);
if (LIKELY(s <= kMaxSmallSize)) {
return (static_cast<uint32_t>(s) + 7) >> 3;
return SmallSizeClass(s);
} else {
return (static_cast<uint32_t>(s) + 127 + (120 << 7)) >> 7;
return LargeSizeClass(s);
}
}
@ -222,10 +230,23 @@ class SizeMap {
// Initialize the mapping arrays
void Init();
inline int SizeClass(int size) {
inline int SizeClass(size_t size) {
return class_array_[ClassIndex(size)];
}
inline bool MaybeSizeClass(size_t size, size_t *size_class) {
size_t class_idx;
if (LIKELY(size <= kMaxSmallSize)) {
class_idx = SmallSizeClass(size);
} else if (size <= kMaxSize) {
class_idx = LargeSizeClass(size);
} else {
return false;
}
*size_class = class_array_[class_idx];
return true;
}
// Get the byte-size for a specified class
inline size_t ByteSizeForClass(size_t cl) {
return class_to_size_[cl];