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Merged
hvitved merged 6 commits into from
Jun 1, 2021
Merged

C#: Various CFG related performance tweaks #5936

hvitved merged 6 commits into from
Jun 1, 2021

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@hvitved hvitved commented May 21, 2021 •
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  • Commit 1: Enforce early join on succ in SplitImpl::hasSuccessor.
  • Commit 2: Use unique in place of forall to avoid large Cartesian products.
  • Commit 3: Use Compilation::getOutputAssembly() to simplify ControlFlowElement::getAssembly(). This change is strictly speaking not needed, because Commit 4 removes the use of ControlFlowElement::getAssembly(), but it is a nice improvement regardless.
  • Commit 4: Remove complexity introduced on C#: Reduce size of getAThrownException() #990, since we can no longer have multiple corelibs (C#: Remove assembly prefixes from TRAP labels #4017).
  • Commit 5: Avoid recomputing a potentially expensive boundedFastTC relation multiple times.
  • Commit 6: This commit removes some false-positives on mono/mono and dotnet/runtime that were uncovered by Commit 4. (Commit 4 meant that some code that previously did not have a CFG now does.)

https://jenkins.internal.semmle.com/job/Changes/job/CSharp-Differences/1087/
https://jenkins.internal.semmle.com/job/Changes/job/CSharp-Differences/1093/

These changes mostly make a difference for Extremely Big databases.

@github-actions github-actions bot added the C# label May 21, 2021
@hvitved hvitved force-pushed the csharp/cfg/perf-tweaks branch 2 times, most recently from 8c2512c to 1db98ce Compare May 22, 2021 07:55
hvitved added 5 commits May 23, 2021 14:14
@hvitved
C#: Improve join-order in SplitImpl::hasSuccessor
2361476 
Joining on `succ` first gets rid of bad join-orders like

```
Tuple counts for Splitting::SplitImpl::hasSuccessor_dispred#ffff/4@i4#f49ebw:
                      59306        ~2%          {3} r1 = JOIN Splitting::SplitImpl::appliesTo#ff#prev_delta WITH Splitting::Cached::TAssertionSplit#ffff_30#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.0 'this', Lhs.1 'pred'
                      454395       ~0%          {3} r2 = JOIN r1 WITH Splitting::AssertionSplitting::getAnAssertionDescendant#ff ON FIRST 1 OUTPUT Lhs.2 'pred', Rhs.1 'succ', Lhs.1 'this'
                      12157        ~0%          {4} r3 = JOIN r2 WITH ControlFlowGraphImpl::succ#fff ON FIRST 2 OUTPUT Lhs.2 'this', Lhs.0 'pred', Lhs.1 'succ', Rhs.2 'c'

                      0            ~0%          {4} r4 = JOIN Splitting::LoopSplitting::LoopUnrollingSplitImpl::appliesToPredecessor_dispred#fff#prev_delta WITH Splitting::Cached::TLoopSplit#ff_10#join_rhs ON FIRST 1 OUTPUT Lhs.1 'pred', Lhs.2 'c', Rhs.1, Rhs.0
                      0            ~0%          {5} r5 = JOIN r4 WITH ControlFlowGraphImpl::succ#fff_021#join_rhs ON FIRST 2 OUTPUT Lhs.2, Lhs.3 'this', Lhs.0 'pred', Lhs.1 'c', Rhs.2 'succ'
                      0            ~0%          {5} r6 = r5 AND NOT Splitting::SplitImpl::hasSuccessor_dispred#ffff#antijoin_rhs#2(Lhs.2 'pred', Lhs.4 'succ', Lhs.3 'c', Lhs.0)
                      0            ~0%          {4} r7 = SCAN r6 OUTPUT In.1 'this', In.2 'pred', In.4 'succ', In.3 'c'

                      12157        ~0%          {4} r8 = r3 UNION r7

                      0            ~0%          {3} r9 = SCAN Splitting::BooleanSplitting::BooleanSplitImpl::appliesToBlock_dispred#fff#prev_delta OUTPUT In.1, In.0 'this', In.2

                      0            ~0%          {4} r10 = JOIN r9 WITH project#PreBasicBlocks::PreBasicBlock::getElement_dispred#fff ON FIRST 1 OUTPUT Rhs.1 'pred', Lhs.1 'this', Lhs.0, Lhs.2
                      0            ~0%          {6} r11 = JOIN r10 WITH ControlFlowGraphImpl::succ#fff ON FIRST 1 OUTPUT Lhs.1 'this', Lhs.2, Lhs.3, Lhs.0 'pred', Rhs.1, Rhs.2 'c'
                      0            ~0%          {6} r12 = r11 AND NOT PreBasicBlocks::PreBasicBlock::getLastElement_dispred#ff(Lhs.1, Lhs.3 'pred')
                      0            ~0%          {4} r13 = SCAN r12 OUTPUT In.0 'this', In.3 'pred', In.4 'succ', In.5 'c'

                      35244        ~1%          {3} r14 = JOIN Splitting::SplitImpl::appliesTo#ff#prev_delta WITH Splitting::Cached::TInitializerSplit#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.0 'this', Lhs.1 'pred'
                      24640675     ~6%          {3} r15 = JOIN r14 WITH Splitting::InitializerSplitting::constructorInitializes#ff ON FIRST 1 OUTPUT Rhs.1, Lhs.1 'this', Lhs.2 'pred'
                      24640675     ~21147%      {3} r16 = JOIN r15 WITH Splitting::InitializerSplitting::InitializedInstanceMember::getInitializer_dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.1 'this', Lhs.2 'pred'
                      470227342920 ~481608%     {3} r17 = JOIN r16 WITH Splitting::InitializerSplitting::InitializedInstanceMember::getAnInitializerDescendant#ff ON FIRST 1 OUTPUT Lhs.2 'pred', Rhs.1 'succ', Lhs.1 'this'
                      24560447     ~66468%      {4} r18 = JOIN r17 WITH ControlFlowGraphImpl::succ#fff ON FIRST 2 OUTPUT Lhs.2 'this', Lhs.0 'pred', Lhs.1 'succ', Rhs.2 'c'

                      24560447     ~66468%      {4} r19 = r13 UNION r18
                      24572604     ~48162%      {4} r20 = r8 UNION r19

                      0            ~0%          {3} r21 = JOIN r9 WITH project#PreBasicBlocks::PreBasicBlock::getElement_dispred#fff ON FIRST 1 OUTPUT Rhs.1 'pred', Lhs.2, Lhs.1 'this'
                      0            ~0%          {4} r22 = JOIN r21 WITH ControlFlowGraphImpl::succ#fff_021#join_rhs ON FIRST 2 OUTPUT Lhs.2 'this', Lhs.0 'pred', Rhs.2 'succ', Rhs.1
                      0            ~0%          {5} r23 = JOIN r22 WITH Splitting::Cached::TBooleanSplit#fff_20#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.2 'succ', Lhs.0 'this', Lhs.1 'pred', Lhs.3 'c'
                      0            ~0%          {4} r24 = JOIN r23 WITH Splitting::BooleanSplitting::SsaBooleanSplitSubKind::canReachCorrelatedCondition#ff ON FIRST 2 OUTPUT Lhs.2 'this', Lhs.3 'pred', Lhs.1 'succ', Lhs.4 'c'

                      0            ~0%          {2} r25 = SCAN Splitting::FinallySplitting::FinallySplitImpl::appliesToPredecessor_dispred#ff#prev_delta OUTPUT In.1 'pred', In.0 'this'

                      0            ~0%          {4} r26 = JOIN r25 WITH ControlFlowGraphImpl::succ#fff ON FIRST 1 OUTPUT Lhs.1 'this', Lhs.0 'pred', Rhs.1, Rhs.2 'c'
                      0            ~0%          {4} r27 = r26 AND NOT Splitting::FinallySplitting::FinallyControlFlowElement::isEntryNode_dispred#f(Lhs.2 'succ')
                      0            ~0%          {5} r28 = JOIN r27 WITH Splitting::Cached::TFinallySplit#fff_21#join_rhs ON FIRST 1 OUTPUT Lhs.2 'succ', Lhs.0 'this', Lhs.1 'pred', Lhs.3 'c', Rhs.1
                      0            ~0%          {6} r29 = JOIN r28 WITH ControlFlowGraphImpl::Statements::TryStmtTree::getAFinallyDescendant#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.1 'this', Lhs.2 'pred', Lhs.0 'succ', Lhs.3 'c', Lhs.4
                      0            ~0%          {7} r30 = JOIN r29 WITH ControlFlowGraphImpl::Statements::TryStmtTree::nestLevel_dispred#ff ON FIRST 1 OUTPUT Lhs.1 'this', Lhs.2 'pred', Lhs.3 'succ', Lhs.4 'c', Lhs.5, Lhs.0, Rhs.1
                      0            ~0%          {7} r31 = SELECT r30 ON In.6 >= In.4
                      0            ~0%          {4} r32 = SCAN r31 OUTPUT In.0 'this', In.1 'pred', In.2 'succ', In.3 'c'

                      0            ~0%          {4} r33 = r24 UNION r32

                      0            ~0%          {4} r34 = JOIN r25 WITH ControlFlowGraphImpl::succ#fff ON FIRST 1 OUTPUT Rhs.1, Lhs.1 'this', Lhs.0 'pred', Rhs.2 'c'
                      0            ~0%          {4} r35 = JOIN r34 WITH Splitting::FinallySplitting::FinallyControlFlowElement::isEntryNode_dispred#f ON FIRST 1 OUTPUT Lhs.1 'this', Lhs.2 'pred', Lhs.0 'succ', Lhs.3 'c'
                      0            ~0%          {5} r36 = JOIN r35 WITH Splitting::Cached::TFinallySplit#fff_21#join_rhs ON FIRST 1 OUTPUT Lhs.2 'succ', Lhs.0 'this', Lhs.1 'pred', Lhs.3 'c', Rhs.1
                      0            ~0%          {6} r37 = JOIN r36 WITH ControlFlowGraphImpl::Statements::TryStmtTree::getAFinallyDescendant#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.1 'this', Lhs.2 'pred', Lhs.0 'succ', Lhs.3 'c', Lhs.4
                      0            ~0%          {7} r38 = JOIN r37 WITH ControlFlowGraphImpl::Statements::TryStmtTree::nestLevel_dispred#ff ON FIRST 1 OUTPUT Lhs.1 'this', Lhs.2 'pred', Lhs.3 'succ', Lhs.4 'c', Lhs.5, Lhs.0, Rhs.1
                      0            ~0%          {7} r39 = SELECT r38 ON In.6 > In.4
                      0            ~0%          {4} r40 = SCAN r39 OUTPUT In.0 'this', In.1 'pred', In.2 'succ', In.3 'c'

                      0            ~0%          {3} r41 = SCAN Splitting::ExceptionHandlerSplitting::ExceptionHandlerSplitImpl::appliesToPredecessor_dispred#fff#prev_delta OUTPUT In.1 'pred', In.2 'c', In.0 'this'
                      0            ~0%          {4} r42 = JOIN r41 WITH ControlFlowGraphImpl::last#fff_120#join_rhs ON FIRST 2 OUTPUT Rhs.2, Lhs.2 'this', Lhs.0 'pred', Lhs.1 'c'
                      0            ~0%          {5} r43 = JOIN r42 WITH Stmt::TryStmt::getCatchClause_dispred#fff_201#join_rhs ON FIRST 1 OUTPUT Rhs.1, Rhs.2, Lhs.1 'this', Lhs.2 'pred', Lhs.3 'c'
                      0            ~0%          {4} r44 = JOIN r43 WITH Stmt::TryStmt::getCatchClause_dispred#fff ON FIRST 2 OUTPUT Rhs.2, Lhs.2 'this', Lhs.3 'pred', Lhs.4 'c'
                      0            ~0%          {5} r45 = JOIN r44 WITH Stmt::CatchClause::isLast_dispred#f ON FIRST 1 OUTPUT Lhs.0, 1, Lhs.1 'this', Lhs.2 'pred', Lhs.3 'c'
                      0            ~0%          {3} r46 = JOIN r45 WITH catch_type_02#join_rhs ON FIRST 2 OUTPUT Lhs.2 'this', Lhs.3 'pred', Lhs.4 'c'
                      0                         {3} r47 = MATERIALIZE r46 AS unknown

                      0            ~0%          {3} r48 = Splitting::ExceptionHandlerSplitting::ExceptionHandlerSplitImpl::appliesToPredecessor_dispred#fff#prev_delta AND NOT r47(Lhs.0 'this', Lhs.1 'pred', Lhs.2 'c')
                      0            ~0%          {3} r49 = SCAN r48 OUTPUT In.1 'pred', In.2 'c', In.0 'this'

                      0            ~0%          {4} r50 = JOIN r49 WITH ControlFlowGraphImpl::succ#fff_021#join_rhs ON FIRST 2 OUTPUT Lhs.2 'this', Lhs.0 'pred', Lhs.1 'c', Rhs.2 'succ'

                      0            ~0%          {4} r51 = JOIN r49 WITH ControlFlowGraphImpl::succ#fff_021#join_rhs ON FIRST 2 OUTPUT Rhs.2 'succ', Lhs.2 'this', Lhs.0 'pred', Lhs.1 'c'
                      0            ~0%          {5} r52 = JOIN r51 WITH ControlFlowGraphImpl::ControlFlowTree::first_dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, Lhs.1 'this', Lhs.2 'pred', Lhs.3 'c', Lhs.0 'succ'
                      0            ~0%          {6} r53 = JOIN r52 WITH Stmt::CatchClause::getBlock_dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, 1, Lhs.1 'this', Lhs.2 'pred', Lhs.3 'c', Lhs.4 'succ'
                      0            ~0%          {4} r54 = JOIN r53 WITH catch_type_02#join_rhs ON FIRST 2 OUTPUT Lhs.2 'this', Lhs.3 'pred', Lhs.4 'c', Lhs.5 'succ'
                      0                         {4} r55 = MATERIALIZE r54 AS unknown

                      0            ~0%          {4} r56 = r50 AND NOT r55(Lhs.0 'this', Lhs.1 'pred', Lhs.2 'c', Lhs.3 'succ')
                      0            ~0%          {4} r57 = r56 AND NOT ControlFlowGraphImpl::Statements::StandardStmt::getChildElement0_dispred#fff#antijoin_rhs#2(Lhs.3 'succ')
                      0            ~0%          {4} r58 = SCAN r57 OUTPUT In.0 'this', In.1 'pred', In.3 'succ', In.2 'c'

                      0            ~0%          {4} r59 = r40 UNION r58
                      0            ~0%          {4} r60 = r33 UNION r59
                      24572604     ~48162%      {4} r61 = r20 UNION r60
                      24572604     ~48162%      {4} r62 = r61 AND NOT Splitting::SplitImpl::hasSuccessor_dispred#ffff#prev(Lhs.0 'this', Lhs.1 'pred', Lhs.2 'succ', Lhs.3 'c')
                                                return r62
```
@hvitved
C#: Rewrite predicates from using forall to using unique
5102fcd 
This avoids generation of expensive anti-join predicates with Cartesian products.
@hvitved
C#: Redefine ControlFlowElement::getAssembly
3162e12
@hvitved
C#: Simplify TriedControlFlowElement::getAThrownException()
088a1a9
@hvitved
C#: Avoid recomputing ControlFlowTree::Range outside the CFG constr…
0d14b94 
…uction stage
@hvitved hvitved force-pushed the csharp/cfg/perf-tweaks branch from 1db98ce to 0d14b94 Compare May 23, 2021 12:14
@hvitved hvitved marked this pull request as ready for review May 31, 2021 07:47
@hvitved hvitved requested a review from a team as a code owner May 31, 2021 07:47
@hvitved hvitved added the no-change-note-required This PR does not need a change note label May 31, 2021
@hvitved hvitved merged commit 5771b04 into github:main Jun 1, 2021
@hvitved hvitved deleted the csharp/cfg/perf-tweaks branch June 1, 2021 09:06
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