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Change heap sort of descriptor array to bottom-up.

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Review URL: http://codereview.chromium.org/661470

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4013 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
whesse@chromium.org 2010-03-04 09:27:45 +00:00
parent 5cee8eeb3d
commit f4190f9876
1 changed files with 31 additions and 24 deletions
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55
src/objects.cc
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@ -3430,18 +3430,25 @@ void DescriptorArray::Sort() {
int len = number_of_descriptors();
// Bottom-up max-heap construction.
for (int i = 1; i < len; ++i) {
int child_index = i;
while (child_index > 0) {
int parent_index = ((child_index + 1) >> 1) - 1;
uint32_t parent_hash = GetKey(parent_index)->Hash();
// Index of the last node with children
const int max_parent_index = (len / 2) - 1;
for (int i = max_parent_index; i >= 0; --i) {
int parent_index = i;
const uint32_t parent_hash = GetKey(i)->Hash();
while (parent_index <= max_parent_index) {
int child_index = 2 * parent_index + 1;
uint32_t child_hash = GetKey(child_index)->Hash();
if (parent_hash < child_hash) {
Swap(parent_index, child_index);
} else {
break;
if (child_index + 1 < len) {
uint32_t right_child_hash = GetKey(child_index + 1)->Hash();
if (right_child_hash > child_hash) {
child_index++;
child_hash = right_child_hash;
}
}
child_index = parent_index;
if (child_hash <= parent_hash) break;
Swap(parent_index, child_index);
// Now element at child_index could be < its children.
parent_index = child_index; // parent_hash remains correct.
}
}
@ -3451,21 +3458,21 @@ void DescriptorArray::Sort() {
Swap(0, i);
// Sift down the new top element.
int parent_index = 0;
while (true) {
int child_index = ((parent_index + 1) << 1) - 1;
if (child_index >= i) break;
uint32_t child1_hash = GetKey(child_index)->Hash();
uint32_t child2_hash = GetKey(child_index + 1)->Hash();
uint32_t parent_hash = GetKey(parent_index)->Hash();
if (child_index + 1 >= i || child1_hash > child2_hash) {
if (parent_hash > child1_hash) break;
Swap(parent_index, child_index);
parent_index = child_index;
} else {
if (parent_hash > child2_hash) break;
Swap(parent_index, child_index + 1);
parent_index = child_index + 1;
const uint32_t parent_hash = GetKey(parent_index)->Hash();
const int max_parent_index = (i / 2) - 1;
while (parent_index <= max_parent_index) {
int child_index = parent_index * 2 + 1;
uint32_t child_hash = GetKey(child_index)->Hash();
if (child_index + 1 < i) {
uint32_t right_child_hash = GetKey(child_index + 1)->Hash();
if (right_child_hash > child_hash) {
child_index++;
child_hash = right_child_hash;
}
}
if (child_hash <= parent_hash) break;
Swap(parent_index, child_index);
parent_index = child_index;
}
}