16b151745b
The use of transitive closure for BB index calculation has been the cause of an out-of-memory error. This commit switches the calculation to use the `shortestDistances` HOP, which still has the problem that the result needs to fit in RAM, but at least the RAM requirements are sure to be linear in the size of the result. The `shortestDistances` HOP is already used for BB index calculation for the C++ IR and for C#. We could guard even better against OOM by switching the calculation to use manual recursion, but that would undo the much-needed performance improvements we got from #123. This change improves performance on Wireshark, which is notorious for having long basic blocks. When I benchmarked `shortestDistances` for #123, it was slower than TC. With the current evaluator, it looks like `shortestDistances` is faster. Performance before was: PrimitiveBasicBlocks::Cached::getMemberIndex#ff ................... 9.7s (executed 8027 times) #PrimitiveBasicBlocks::Cached::member_step#ffPlus ................. 6.6s PrimitiveBasicBlocks::Cached::primitive_basic_block_entry_node#f .. 3.5s PrimitiveBasicBlocks::Cached::primitive_basic_block_member#fff .... 2.3s Performance with this commit is: PrimitiveBasicBlocks::Cached::primitive_basic_block_entry_node#f ................................................................... 3.5s shortestDistances@PrimitiveBasicBlocks::Cached::primitive_basic_block_entry_node#1@PrimitiveBasicBlocks::Cached::member_step#2#fff . 3s PrimitiveBasicBlocks::Cached::primitive_basic_block_member#fff ..................................................................... 963ms
Semmle QL
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