Improve reachability sets computation #84204
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Two changes to improve the throughput of computing `bbReach` sets: 1. In `fgComputeReachabilitySets()`, iterate over the blocks in reverse post-order. This leads to fewer outer `do ... while(change)` iterations. To do this, the `fgDfsReversePostorder()` function which creates the reverse post-order numbers and ordering was hoisted out of dominator creation and above reachability computation. 2. Create a `BlockSetOps::UnionDChanged()` function that does a `UnionD` operation but also returns `true` if the target bitset changed value. Some additional stats were added under `COUNT_BASIC_BLOCKS` regarding how many iterations dominators and reachability computations take to converge.
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch, @kunalspathak Issue DetailsTwo changes to improve the throughput of computing
Some additional stats were added under
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TP improvements up to -0.09% |
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@AndyAyersMS PTAL |
AndyAyersMS
approved these changes
Apr 1, 2023
src/coreclr/jit/bitset.h
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| @@ -228,6 +228,8 @@ class BitSetOps | |||
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| // Destructively modify "bs1" to be the union of "bs1" and "bs2". | |||
| static void UnionD(Env env, BitSetType& bs1, BitSetValueArgType bs2); | |||
| // Destructively modify "bs1" to be the union of "bs1" and "bs2"; return `true` if `bs1` changed. | |||
| static void UnionDChanged(Env env, BitSetType& bs1, BitSetValueArgType bs2); | |||
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Suggested change
| static void UnionDChanged(Env env, BitSetType& bs1, BitSetValueArgType bs2); | |
| static bool UnionDChanged(Env env, BitSetType& bs1, BitSetValueArgType bs2); |
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Two changes to improve the throughput of computing
bbReachsets:fgComputeReachabilitySets(), iterate over the blocks in reverse post-order. This leads to fewer outerdo ... while(change)iterations. To do this, thefgDfsReversePostorder()function which creates the reverse post-order numbers and ordering was hoisted out of dominator creation and above reachability computation.BlockSetOps::UnionDChanged()function that does aUnionDoperation but also returnstrueif the target bitset changed value.Some additional stats were added under
COUNT_BASIC_BLOCKSregarding how many iterations dominators and reachability computations take to converge.