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Fix a possible overflow in TT resize

Browse source 
On platforms where size_t is 32 bit, we
can have an overflow in this expression:

(mbSize * 1024 * 1024)

Fix it setting max hash size of 2GB on platforms
where size_t is 32 bit.

A small rename while there: now struct Cluster
is definied inside class TranspositionTable so
we should drop the redundant TT prefix.

No functional change.
This commit is contained in:
Marco Costalba 2015-01-17 09:04:25 +01:00
parent 58fdb84b0d
commit 595fc342cf
3 changed files with 10 additions and 8 deletions
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10
src/tt.cpp
View file

@ -32,9 +32,9 @@ TranspositionTable TT; // Our global transposition table
void TranspositionTable::resize(size_t mbSize) {
assert(sizeof(TTCluster) == CacheLineSize / 2);
assert(sizeof(Cluster) == CacheLineSize / 2);
size_t newClusterCount = size_t(1) << msb((mbSize * 1024 * 1024) / sizeof(TTCluster));
size_t newClusterCount = size_t(1) << msb((mbSize * 1024 * 1024) / sizeof(Cluster));
if (newClusterCount == clusterCount)
return;
@ -42,7 +42,7 @@ void TranspositionTable::resize(size_t mbSize) {
clusterCount = newClusterCount;
free(mem);
mem = calloc(clusterCount * sizeof(TTCluster) + CacheLineSize - 1, 1);
mem = calloc(clusterCount * sizeof(Cluster) + CacheLineSize - 1, 1);
if (!mem)
{
@ -51,7 +51,7 @@ void TranspositionTable::resize(size_t mbSize) {
exit(EXIT_FAILURE);
}
table = (TTCluster*)((uintptr_t(mem) + CacheLineSize - 1) & ~(CacheLineSize - 1));
table = (Cluster*)((uintptr_t(mem) + CacheLineSize - 1) & ~(CacheLineSize - 1));
}
@ -61,7 +61,7 @@ void TranspositionTable::resize(size_t mbSize) {
void TranspositionTable::clear() {
std::memset(table, 0, clusterCount * sizeof(TTCluster));
std::memset(table, 0, clusterCount * sizeof(Cluster));
}

4
src/tt.h
View file

@ -76,7 +76,7 @@ class TranspositionTable {
static const int CacheLineSize = 64;
static const int TTClusterSize = 3;
struct TTCluster {
struct Cluster {
TTEntry entry[TTClusterSize];
char padding[2]; // Align to the cache line size
};
@ -96,7 +96,7 @@ public:
private:
size_t clusterCount;
TTCluster* table;
Cluster* table;
void* mem;
uint8_t generation8; // Size must be not bigger than TTEntry::genBound8
};

4
src/ucioption.cpp
View file

@ -54,11 +54,13 @@ bool CaseInsensitiveLess::operator() (const string& s1, const string& s2) const
void init(OptionsMap& o) {
const int MaxHashMB = Is64Bit ? 1024 * 1024 : 2048;
o["Write Debug Log"] << Option(false, on_logger);
o["Contempt"] << Option(0, -100, 100);
o["Min Split Depth"] << Option(0, 0, 12, on_threads);
o["Threads"] << Option(1, 1, MAX_THREADS, on_threads);
o["Hash"] << Option(16, 1, 1024 * 1024, on_hash_size);
o["Hash"] << Option(16, 1, MaxHashMB, on_hash_size);
o["Clear Hash"] << Option(on_clear_hash);
o["Ponder"] << Option(true);
o["MultiPV"] << Option(1, 1, 500);