aboutsummaryrefslogtreecommitdiffstats
path: root/lib/Support
diff options
context:
space:
mode:
authorBenjamin Kramer <benny.kra@googlemail.com>2011-12-27 20:35:07 +0000
committerBenjamin Kramer <benny.kra@googlemail.com>2011-12-27 20:35:07 +0000
commitc894b02ae037b5fdb38e42535539d5a0e49d6c41 (patch)
tree4224ea17ee6ca28dc887aa07808cf14c1ee94f7a /lib/Support
parent91968489d718b313d4c0b912062e75a82db650e7 (diff)
downloadexternal_llvm-c894b02ae037b5fdb38e42535539d5a0e49d6c41.zip
external_llvm-c894b02ae037b5fdb38e42535539d5a0e49d6c41.tar.gz
external_llvm-c894b02ae037b5fdb38e42535539d5a0e49d6c41.tar.bz2
Switch StringMap from an array of structures to a structure of arrays.
- -25% memory usage of the main table on x86_64 (was wasted in struct padding). - no significant performance change. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147294 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Support')
-rw-r--r--lib/Support/StringMap.cpp61
1 files changed, 34 insertions, 27 deletions
diff --git a/lib/Support/StringMap.cpp b/lib/Support/StringMap.cpp
index a1ac512..c131fe0 100644
--- a/lib/Support/StringMap.cpp
+++ b/lib/Support/StringMap.cpp
@@ -39,11 +39,13 @@ void StringMapImpl::init(unsigned InitSize) {
NumItems = 0;
NumTombstones = 0;
- TheTable = (ItemBucket*)calloc(NumBuckets+1, sizeof(ItemBucket));
-
+ TheTable = (StringMapEntryBase **)calloc(NumBuckets+1,
+ sizeof(StringMapEntryBase **) +
+ sizeof(unsigned));
+
// Allocate one extra bucket, set it to look filled so the iterators stop at
// end.
- TheTable[NumBuckets].Item = (StringMapEntryBase*)2;
+ TheTable[NumBuckets] = (StringMapEntryBase*)2;
}
@@ -60,29 +62,29 @@ unsigned StringMapImpl::LookupBucketFor(StringRef Name) {
}
unsigned FullHashValue = HashString(Name);
unsigned BucketNo = FullHashValue & (HTSize-1);
-
+ unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1);
+
unsigned ProbeAmt = 1;
int FirstTombstone = -1;
while (1) {
- ItemBucket &Bucket = TheTable[BucketNo];
- StringMapEntryBase *BucketItem = Bucket.Item;
+ StringMapEntryBase *BucketItem = TheTable[BucketNo];
// If we found an empty bucket, this key isn't in the table yet, return it.
if (BucketItem == 0) {
// If we found a tombstone, we want to reuse the tombstone instead of an
// empty bucket. This reduces probing.
if (FirstTombstone != -1) {
- TheTable[FirstTombstone].FullHashValue = FullHashValue;
+ HashTable[FirstTombstone] = FullHashValue;
return FirstTombstone;
}
- Bucket.FullHashValue = FullHashValue;
+ HashTable[BucketNo] = FullHashValue;
return BucketNo;
}
if (BucketItem == getTombstoneVal()) {
// Skip over tombstones. However, remember the first one we see.
if (FirstTombstone == -1) FirstTombstone = BucketNo;
- } else if (Bucket.FullHashValue == FullHashValue) {
+ } else if (HashTable[BucketNo] == FullHashValue) {
// If the full hash value matches, check deeply for a match. The common
// case here is that we are only looking at the buckets (for item info
// being non-null and for the full hash value) not at the items. This
@@ -115,18 +117,18 @@ int StringMapImpl::FindKey(StringRef Key) const {
if (HTSize == 0) return -1; // Really empty table?
unsigned FullHashValue = HashString(Key);
unsigned BucketNo = FullHashValue & (HTSize-1);
-
+ unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1);
+
unsigned ProbeAmt = 1;
while (1) {
- ItemBucket &Bucket = TheTable[BucketNo];
- StringMapEntryBase *BucketItem = Bucket.Item;
+ StringMapEntryBase *BucketItem = TheTable[BucketNo];
// If we found an empty bucket, this key isn't in the table yet, return.
if (BucketItem == 0)
return -1;
if (BucketItem == getTombstoneVal()) {
// Ignore tombstones.
- } else if (Bucket.FullHashValue == FullHashValue) {
+ } else if (HashTable[BucketNo] == FullHashValue) {
// If the full hash value matches, check deeply for a match. The common
// case here is that we are only looking at the buckets (for item info
// being non-null and for the full hash value) not at the items. This
@@ -165,8 +167,8 @@ StringMapEntryBase *StringMapImpl::RemoveKey(StringRef Key) {
int Bucket = FindKey(Key);
if (Bucket == -1) return 0;
- StringMapEntryBase *Result = TheTable[Bucket].Item;
- TheTable[Bucket].Item = getTombstoneVal();
+ StringMapEntryBase *Result = TheTable[Bucket];
+ TheTable[Bucket] = getTombstoneVal();
--NumItems;
++NumTombstones;
assert(NumItems + NumTombstones <= NumBuckets);
@@ -180,6 +182,7 @@ StringMapEntryBase *StringMapImpl::RemoveKey(StringRef Key) {
/// the appropriate mod-of-hashtable-size.
void StringMapImpl::RehashTable() {
unsigned NewSize;
+ unsigned *HashTable = (unsigned *)(TheTable + NumBuckets + 1);
// If the hash table is now more than 3/4 full, or if fewer than 1/8 of
// the buckets are empty (meaning that many are filled with tombstones),
@@ -194,19 +197,23 @@ void StringMapImpl::RehashTable() {
// Allocate one extra bucket which will always be non-empty. This allows the
// iterators to stop at end.
- ItemBucket *NewTableArray =(ItemBucket*)calloc(NewSize+1, sizeof(ItemBucket));
- NewTableArray[NewSize].Item = (StringMapEntryBase*)2;
-
+ StringMapEntryBase **NewTableArray =
+ (StringMapEntryBase **)calloc(NewSize+1, sizeof(StringMapEntryBase *) +
+ sizeof(unsigned));
+ unsigned *NewHashArray = (unsigned *)(NewTableArray + NewSize + 1);
+ NewTableArray[NewSize] = (StringMapEntryBase*)2;
+
// Rehash all the items into their new buckets. Luckily :) we already have
// the hash values available, so we don't have to rehash any strings.
- for (ItemBucket *IB = TheTable, *E = TheTable+NumBuckets; IB != E; ++IB) {
- if (IB->Item && IB->Item != getTombstoneVal()) {
+ for (unsigned I = 0, E = NumBuckets; I != E; ++I) {
+ StringMapEntryBase *Bucket = TheTable[I];
+ if (Bucket && Bucket != getTombstoneVal()) {
// Fast case, bucket available.
- unsigned FullHash = IB->FullHashValue;
+ unsigned FullHash = HashTable[I];
unsigned NewBucket = FullHash & (NewSize-1);
- if (NewTableArray[NewBucket].Item == 0) {
- NewTableArray[FullHash & (NewSize-1)].Item = IB->Item;
- NewTableArray[FullHash & (NewSize-1)].FullHashValue = FullHash;
+ if (NewTableArray[NewBucket] == 0) {
+ NewTableArray[FullHash & (NewSize-1)] = Bucket;
+ NewHashArray[FullHash & (NewSize-1)] = FullHash;
continue;
}
@@ -214,11 +221,11 @@ void StringMapImpl::RehashTable() {
unsigned ProbeSize = 1;
do {
NewBucket = (NewBucket + ProbeSize++) & (NewSize-1);
- } while (NewTableArray[NewBucket].Item);
+ } while (NewTableArray[NewBucket]);
// Finally found a slot. Fill it in.
- NewTableArray[NewBucket].Item = IB->Item;
- NewTableArray[NewBucket].FullHashValue = FullHash;
+ NewTableArray[NewBucket] = Bucket;
+ NewHashArray[NewBucket] = FullHash;
}
}