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Make sure ImmutableSet never inserts Tombstone/Entry into DenseMap.

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ImmutAVLTree uses random unsigned values as keys into a DenseMap,
which could possibly happen to be the same value as the Tombstone or
Entry keys in the DenseMap.

Test case is hard to come up with. We randomly get failures on the
internal static analyzer bot, which most likely hits this issue
(hard to be 100% sure without the full stack).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153148 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Anna Zaks 2012-03-20 22:56:27 +00:00
parent 5069b21b45
commit 4211c196d4
1 changed files with 7 additions and 2 deletions
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9
include/llvm/ADT/ImmutableSet.h
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@ -347,7 +347,7 @@ public:
if (prev) if (prev)
prev->next = next; prev->next = next;
else else
factory->Cache[computeDigest()] = next; factory->Cache[factory->maskCacheIndex(computeDigest())] = next;
} }
// We need to clear the mutability bit in case we are // We need to clear the mutability bit in case we are
@ -429,6 +429,11 @@ protected:
TreeTy* getRight(TreeTy* T) const { return T->getRight(); } TreeTy* getRight(TreeTy* T) const { return T->getRight(); }
value_type_ref getValue(TreeTy* T) const { return T->value; } value_type_ref getValue(TreeTy* T) const { return T->value; }
// Make sure the index is not the Tombstone or Entry key of the DenseMap.
static inline unsigned maskCacheIndex(unsigned I) {
return (I & ~0x02);
}
unsigned incrementHeight(TreeTy* L, TreeTy* R) const { unsigned incrementHeight(TreeTy* L, TreeTy* R) const {
unsigned hl = getHeight(L); unsigned hl = getHeight(L);
unsigned hr = getHeight(R); unsigned hr = getHeight(R);
@ -611,7 +616,7 @@ public:
// Search the hashtable for another tree with the same digest, and // Search the hashtable for another tree with the same digest, and
// if find a collision compare those trees by their contents. // if find a collision compare those trees by their contents.
unsigned digest = TNew->computeDigest(); unsigned digest = TNew->computeDigest();
TreeTy *&entry = Cache[digest]; TreeTy *&entry = Cache[maskCacheIndex(digest)];
do { do {
if (!entry) if (!entry)
break; break;