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Merge pull request #2412 from atn34/atn34/fix-skiplist-ub 

Fix ub in MiniConflictSet (Skiplist.cpp)
This commit is contained in:
A.J. Beamon 2019-12-05 20:20:30 -08:00 committed by GitHub
parent db4666508a 9188344d7b
commit d94a1dfef2
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 14 additions and 15 deletions
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29
fdbserver/SkipList.cpp
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@ -1035,8 +1035,8 @@ class MiniConflictSet : NonCopyable {
std::vector<wordType> andValues;
MiniConflictSet2 debug; // SOMEDAY: Test on big ranges, eliminate this
uint64_t bitMask(unsigned int bit){ // computes results for bit%word
return (((wordType)1) << ( bit & bucketMask )); // '&' unnecesary?
wordType bitMask(unsigned int bit) { // computes results for bit%word
return (((wordType)1) << (bit & bucketMask));
}
void setNthBit(std::vector<wordType>& v, const unsigned int bit){
v[bit>>bucketShift] |= bitMask(bit);
@ -1052,11 +1052,11 @@ class MiniConflictSet : NonCopyable {
}
wordType highBits(int b){ // bits (b&bucketMask) and higher are 1
#pragma warning(disable: 4146)
return -(wordType(1) << b);
return -bitMask(b);
#pragma warning(default: 4146)
}
wordType lowBits(int b){ // bits lower than b are 1
return (wordType(1)<<b)-1;
wordType lowBits(int b) { // bits lower than (b&bucketMask) are 1
return bitMask(b) - 1;
}
wordType lowBits2(int b) {
return (b&bucketMask) ? lowBits(b) : -1;
@ -1092,6 +1092,15 @@ class MiniConflictSet : NonCopyable {
}
}
bool orImpl(int begin, int end) {
if (begin == end) return false;
int beginWord = begin >> bucketShift;
int lastWord = ((end + bucketMask) >> bucketShift) - 1;
return orBits(orValues, beginWord + 1, lastWord, true) || getNthBit(andValues, beginWord) ||
getNthBit(andValues, lastWord) || orBits(values, begin, end, false);
}
public:
explicit MiniConflictSet( int size ) : debug(size) {
static_assert((1<<bucketShift) == sizeof(wordType)*8, "BucketShift incorrect");
@ -1119,16 +1128,6 @@ public:
ASSERT( a == b );
return b;
}
bool orImpl( int begin, int end ) {
if (begin == end) return false;
int beginWord = begin>>bucketShift;
int lastWord = ((end+bucketMask) >> bucketShift) - 1;
return orBits( orValues, beginWord+1, lastWord, true ) ||
getNthBit( andValues, beginWord ) || getNthBit( andValues, lastWord ) ||
orBits( values, begin, end, false );
}
};