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speed up 3-level page map access

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There is no need to have pointer indirection for root node. This also
helps the case of early free of garbage pointer because we didn't
check root_ pointer for NULL.
This commit is contained in:
Aliaksey Kandratsenka 2017-05-22 02:38:13 -07:00
parent f7ff175b92
commit 83d6818295
1 changed files with 11 additions and 11 deletions
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22
src/pagemap.h
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@ -229,7 +229,7 @@ class TCMalloc_PageMap3 {
void* values[LEAF_LENGTH];
};
Node* root_; // Root of radix tree
Node root_; // Root of radix tree
void* (*allocator_)(size_t); // Memory allocator
Node* NewNode() {
@ -245,7 +245,7 @@ class TCMalloc_PageMap3 {
explicit TCMalloc_PageMap3(void* (*allocator)(size_t)) {
allocator_ = allocator;
root_ = NewNode();
memset(&root_, 0, sizeof(root_));
}
ATTRIBUTE_ALWAYS_INLINE
@ -254,10 +254,10 @@ class TCMalloc_PageMap3 {
const Number i2 = (k >> LEAF_BITS) & (INTERIOR_LENGTH-1);
const Number i3 = k & (LEAF_LENGTH-1);
if ((k >> BITS) > 0 ||
root_->ptrs[i1] == NULL || root_->ptrs[i1]->ptrs[i2] == NULL) {
root_.ptrs[i1] == NULL || root_.ptrs[i1]->ptrs[i2] == NULL) {
return NULL;
}
return reinterpret_cast<Leaf*>(root_->ptrs[i1]->ptrs[i2])->values[i3];
return reinterpret_cast<Leaf*>(root_.ptrs[i1]->ptrs[i2])->values[i3];
}
void set(Number k, void* v) {
@ -265,7 +265,7 @@ class TCMalloc_PageMap3 {
const Number i1 = k >> (LEAF_BITS + INTERIOR_BITS);
const Number i2 = (k >> LEAF_BITS) & (INTERIOR_LENGTH-1);
const Number i3 = k & (LEAF_LENGTH-1);
reinterpret_cast<Leaf*>(root_->ptrs[i1]->ptrs[i2])->values[i3] = v;
reinterpret_cast<Leaf*>(root_.ptrs[i1]->ptrs[i2])->values[i3] = v;
}
bool Ensure(Number start, size_t n) {
@ -278,18 +278,18 @@ class TCMalloc_PageMap3 {
return false;
// Make 2nd level node if necessary
if (root_->ptrs[i1] == NULL) {
if (root_.ptrs[i1] == NULL) {
Node* n = NewNode();
if (n == NULL) return false;
root_->ptrs[i1] = n;
root_.ptrs[i1] = n;
}
// Make leaf node if necessary
if (root_->ptrs[i1]->ptrs[i2] == NULL) {
if (root_.ptrs[i1]->ptrs[i2] == NULL) {
Leaf* leaf = reinterpret_cast<Leaf*>((*allocator_)(sizeof(Leaf)));
if (leaf == NULL) return false;
memset(leaf, 0, sizeof(*leaf));
root_->ptrs[i1]->ptrs[i2] = reinterpret_cast<Node*>(leaf);
root_.ptrs[i1]->ptrs[i2] = reinterpret_cast<Node*>(leaf);
}
// Advance key past whatever is covered by this leaf node
@ -305,11 +305,11 @@ class TCMalloc_PageMap3 {
while (k < (Number(1) << BITS)) {
const Number i1 = k >> (LEAF_BITS + INTERIOR_BITS);
const Number i2 = (k >> LEAF_BITS) & (INTERIOR_LENGTH-1);
if (root_->ptrs[i1] == NULL) {
if (root_.ptrs[i1] == NULL) {
// Advance to next top-level entry
k = (i1 + 1) << (LEAF_BITS + INTERIOR_BITS);
} else {
Leaf* leaf = reinterpret_cast<Leaf*>(root_->ptrs[i1]->ptrs[i2]);
Leaf* leaf = reinterpret_cast<Leaf*>(root_.ptrs[i1]->ptrs[i2]);
if (leaf != NULL) {
for (Number i3 = (k & (LEAF_LENGTH-1)); i3 < LEAF_LENGTH; i3++) {
if (leaf->values[i3] != NULL) {