Howard Hinnant 2aaa47f396 Rehash but don't grow when full of tombstones. ... This problem was found and fixed by José Fonseca in March 2011 for SmallPtrSet, committed r128566. But as far as I can tell, all other llvm hash tables retain the same problem: the bucket count can grow without bound while size() remains near constant by repeated insert/erase cycles that tend to fill the container with tombstones. Here is a demo that has been reduced to a trivial case: int main() { llvm::DenseSet<unsigned> d; for (unsigned i = 0; i < 0xFFFFFFF; ++i) { d.insert(i); d.erase(i); } } While the container size() never grows above 1, the bucket count grows like this: nb = 64 nb = 128 nb = 256 nb = 512 nb = 1024 nb = 2048 nb = 4096 nb = 8192 nb = 16384 nb = 32768 nb = 65536 nb = 131072 nb = 262144 nb = 524288 nb = 1048576 nb = 2097152 nb = 4194304 nb = 8388608 nb = 16777216 nb = 33554432 nb = 67108864 nb = 134217728 nb = 268435456 The above program currently consumes a few GB ram. This patch brings the memory consumption down by several orders of magnitude, and keeps the bucket count at 64 for the above test. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193689 91177308-0d34-0410-b5e6-96231b3b80d8		2013-10-30 15:10:54 +00:00
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llvm	Rehash but don't grow when full of tombstones.	2013-10-30 15:10:54 +00:00
llvm-c	llvm-c: Make LLVM{Get,Set}Alignment work on {Load,Store}Inst too	2013-10-29 09:02:02 +00:00