[llvm-commits] CVS: llvm/lib/Support/StringMap.cpp
Chris Lattner
sabre at nondot.org
Tue Apr 3 17:29:56 PDT 2007
Changes in directory llvm/lib/Support:
StringMap.cpp updated: 1.10 -> 1.11
---
Log message:
Extend StringMap to support being initialized as completely empty. When
initialized this way, they do not do a malloc to allocate their buckets.
---
Diffs of the changes: (+22 -2)
StringMap.cpp | 24 ++++++++++++++++++++++--
1 files changed, 22 insertions(+), 2 deletions(-)
Index: llvm/lib/Support/StringMap.cpp
diff -u llvm/lib/Support/StringMap.cpp:1.10 llvm/lib/Support/StringMap.cpp:1.11
--- llvm/lib/Support/StringMap.cpp:1.10 Tue Apr 3 17:15:38 2007
+++ llvm/lib/Support/StringMap.cpp Tue Apr 3 19:29:37 2007
@@ -16,10 +16,25 @@
using namespace llvm;
StringMapImpl::StringMapImpl(unsigned InitSize, unsigned itemSize) {
+ ItemSize = itemSize;
+
+ // If a size is specified, initialize the table with that many buckets.
+ if (InitSize) {
+ init(InitSize);
+ return;
+ }
+
+ // Otherwise, initialize it with zero buckets to avoid the allocation.
+ TheTable = 0;
+ NumBuckets = 0;
+ NumItems = 0;
+ NumTombstones = 0;
+}
+
+void StringMapImpl::init(unsigned InitSize) {
assert((InitSize & (InitSize-1)) == 0 &&
"Init Size must be a power of 2 or zero!");
NumBuckets = InitSize ? InitSize : 16;
- ItemSize = itemSize;
NumItems = 0;
NumTombstones = 0;
@@ -52,8 +67,12 @@
/// case, the FullHashValue field of the bucket will be set to the hash value
/// of the string.
unsigned StringMapImpl::LookupBucketFor(const char *NameStart,
- const char *NameEnd) {
+ const char *NameEnd) {
unsigned HTSize = NumBuckets;
+ if (HTSize == 0) { // Hash table unallocated so far?
+ init(16);
+ HTSize = NumBuckets;
+ }
unsigned FullHashValue = HashString(NameStart, NameEnd);
unsigned BucketNo = FullHashValue & (HTSize-1);
@@ -110,6 +129,7 @@
/// This does not modify the map.
int StringMapImpl::FindKey(const char *KeyStart, const char *KeyEnd) const {
unsigned HTSize = NumBuckets;
+ if (HTSize == 0) return -1; // Really empty table?
unsigned FullHashValue = HashString(KeyStart, KeyEnd);
unsigned BucketNo = FullHashValue & (HTSize-1);
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