RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2025-01-31 20:51:52 +01:00
Code Issues Projects Releases Wiki Activity

Move StringMap's string has function into StringExtras.h

Browse Source 
llvm-svn: 84344
This commit is contained in:
Daniel Dunbar 2009-10-17 18:21:06 +00:00
parent d0736f38d7
commit 0107265e33
2 changed files with 17 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
include/llvm/ADT/StringExtras.h
View File

@ -16,6 +16,7 @@
#include "llvm/Support/DataTypes.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/StringRef.h"
#include <cctype>
#include <cstdio>
#include <string>
@ -225,6 +226,19 @@ void UnescapeString(std::string &Str);
/// doesn't satisfy std::isprint into an escape sequence.
void EscapeString(std::string &Str);
/// HashString - Hash funtion for strings.
///
/// This is the Bernstein hash function.
//
// FIXME: Investigate whether a modified bernstein hash function performs
// better: http://eternallyconfuzzled.com/tuts/algorithms/jsw_tut_hashing.aspx
// X*33+c -> X*33^c
static inline unsigned HashString(StringRef Str, unsigned Result = 0) {
for (unsigned i = 0, e = Str.size(); i != e; ++i)
Result = Result * 33 + Str[i];
return Result;
}
} // End llvm namespace
#endif

19
lib/Support/StringMap.cpp
View File

@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringExtras.h"
#include <cassert>
using namespace llvm;
@ -46,20 +47,6 @@ void StringMapImpl::init(unsigned InitSize) {
}
/// HashString - Compute a hash code for the specified string.
///
static unsigned HashString(const char *Start, const char *End) {
// Bernstein hash function.
unsigned int Result = 0;
// TODO: investigate whether a modified bernstein hash function performs
// better: http://eternallyconfuzzled.com/tuts/algorithms/jsw_tut_hashing.aspx
// X*33+c -> X*33^c
while (Start != End)
Result = Result * 33 + *Start++;
Result = Result + (Result >> 5);
return Result;
}
/// LookupBucketFor - Look up the bucket that the specified string should end
/// up in. If it already exists as a key in the map, the Item pointer for the
/// specified bucket will be non-null. Otherwise, it will be null. In either
@ -71,7 +58,7 @@ unsigned StringMapImpl::LookupBucketFor(const StringRef &Name) {
init(16);
HTSize = NumBuckets;
}
unsigned FullHashValue = HashString(Name.begin(), Name.end());
unsigned FullHashValue = HashString(Name);
unsigned BucketNo = FullHashValue & (HTSize-1);
unsigned ProbeAmt = 1;
@ -126,7 +113,7 @@ unsigned StringMapImpl::LookupBucketFor(const StringRef &Name) {
int StringMapImpl::FindKey(const StringRef &Key) const {
unsigned HTSize = NumBuckets;
if (HTSize == 0) return -1; // Really empty table?
unsigned FullHashValue = HashString(Key.begin(), Key.end());
unsigned FullHashValue = HashString(Key);
unsigned BucketNo = FullHashValue & (HTSize-1);
unsigned ProbeAmt = 1;