From 38742b9603858db660cbb6b67853ca9266eaa196 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sat, 6 Jan 2007 23:19:38 +0000 Subject: [PATCH] add a note git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32962 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Support/CStringMap.cpp | 5 ++++- lib/Support/StringMap.cpp | 5 ++++- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/lib/Support/CStringMap.cpp b/lib/Support/CStringMap.cpp index 3229bfe50d8..6cd3745946c 100644 --- a/lib/Support/CStringMap.cpp +++ b/lib/Support/CStringMap.cpp @@ -33,8 +33,11 @@ CStringMapImpl::CStringMapImpl(unsigned InitSize, unsigned itemSize) { /// 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; - // Perl hash function. + // TODO: investigate whether a modified bernstein hash function performs + // better: http://eternallyconfuzzled.com/tuts/hashing.html#existing + // X*33+c -> X*33^c while (Start != End) Result = Result * 33 + *Start++; Result = Result + (Result >> 5); diff --git a/lib/Support/StringMap.cpp b/lib/Support/StringMap.cpp index 3229bfe50d8..6cd3745946c 100644 --- a/lib/Support/StringMap.cpp +++ b/lib/Support/StringMap.cpp @@ -33,8 +33,11 @@ CStringMapImpl::CStringMapImpl(unsigned InitSize, unsigned itemSize) { /// 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; - // Perl hash function. + // TODO: investigate whether a modified bernstein hash function performs + // better: http://eternallyconfuzzled.com/tuts/hashing.html#existing + // X*33+c -> X*33^c while (Start != End) Result = Result * 33 + *Start++; Result = Result + (Result >> 5); -- 2.34.1