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Alexey Zhikhartsev 02077da7e7 Add jump-threading optimization for deterministic finite automata 
The current JumpThreading pass does not jump thread loops since it can
result in irreducible control flow that harms other optimizations. This
prevents switch statements inside a loop from being optimized to use
unconditional branches.

This code pattern occurs in the core_state_transition function of
Coremark. The state machine can be implemented manually with goto
statements resulting in a large runtime improvement, and this transform
makes the switch implementation match the goto version in performance.

This patch specifically targets switch statements inside a loop that
have the opportunity to be threaded. Once it identifies an opportunity,
it creates new paths that branch directly to the correct code block.
For example, the left CFG could be transformed to the right CFG:

```
          sw.bb                        sw.bb
        /   |   \                    /   |   \
   case1  case2  case3          case1  case2  case3
        \   |   /                /       |       \
        latch.bb             latch.2  latch.3  latch.1
         br sw.bb              /         |         \
                           sw.bb.2     sw.bb.3     sw.bb.1
                            br case2    br case3    br case1
```

Co-author: Justin Kreiner @jkreiner
Co-author: Ehsan Amiri @amehsan

Reviewed By: SjoerdMeijer

Differential Revision: https://reviews.llvm.org/D99205
 		2021-07-27 14:34:04 -04:00
..
ADCE.cpp [IR] Consider non-willreturn as side effect (PR50511) 2021-07-26 16:35:14 +02:00
AlignmentFromAssumptions.cpp Recommit [ScalarEvolution] Make getMinusSCEV() fail for unrelated pointers. 2021-07-06 12:16:05 -07:00
AnnotationRemarks.cpp [Remarks] Add analysis remarks for memset/memcpy/memmove lengths 2021-05-24 10:10:44 -07:00
BDCE.cpp [NewPM] Don't mark AA analyses as preserved 2021-05-18 13:49:03 -07:00
CMakeLists.txt Add jump-threading optimization for deterministic finite automata 2021-07-27 14:34:04 -04:00
CallSiteSplitting.cpp [Support] Introduce a new InstructionCost class 2020-12-11 08:12:54 +00:00
ConstantHoisting.cpp [TTI] NFC: Change getIntImmCost[Inst|Intrin] to return InstructionCost 2021-04-23 16:06:36 +01:00
ConstraintElimination.cpp [NewPM] Don't mark AA analyses as preserved 2021-05-18 13:49:03 -07:00
CorrelatedValuePropagation.cpp [CVP] Guard against poison in common phi value transform (PR50399) 2021-05-25 20:47:17 +02:00
DCE.cpp [Scalar] Use range-based for loops (NFC) 2021-02-25 19:54:38 -08:00
DFAJumpThreading.cpp Add jump-threading optimization for deterministic finite automata 2021-07-27 14:34:04 -04:00
DeadStoreElimination.cpp Revert "[DSE] Transform memset + malloc --> calloc (PR25892)" 2021-07-23 11:51:59 +02:00
DivRemPairs.cpp [DivRemPairs] Add an initial case for hoisting to a common predecessor. 2021-07-11 10:03:07 -07:00
EarlyCSE.cpp [FPEnv] EarlyCSE support for constrained intrinsics, default FP environment edition 2021-05-20 14:40:51 -04:00
FlattenCFGPass.cpp [NFC] Reduce include files dependency and AA header cleanup (part 2). 2020-12-17 14:04:48 +03:00
Float2Int.cpp [NFCI] Move DEBUG_TYPE definition below #includes 2021-05-30 17:31:01 +08:00
GVN.cpp GVN.cpp - remove unused <vector> include. NFCI. 2021-06-13 14:06:32 +01:00
GVNHoist.cpp [NewPM] Don't mark AA analyses as preserved 2021-05-18 13:49:03 -07:00
GVNSink.cpp [NewPM] Don't mark AA analyses as preserved 2021-05-18 13:49:03 -07:00
GuardWidening.cpp [llvm] Use llvm::all_of (NFC) 2021-01-19 20:19:17 -08:00
IVUsersPrinter.cpp
…
IndVarSimplify.cpp [IndVarSimplify][NFC] Removed mayThrow from if-condition in predicateLoopExits of IndVarSimplify 2021-05-03 18:25:07 -07:00
InductiveRangeCheckElimination.cpp [NFC][NewPM] Remove some AnalysisManager invalidate methods 2021-04-15 16:51:26 -07:00
InferAddressSpaces.cpp [infer-address-spaces] Handle complex non-pointer constexpr arguments. 2021-07-19 12:15:52 -07:00
InstSimplifyPass.cpp
…
JumpThreading.cpp [CSSPGO] Undoing the concept of dangling pseudo probe 2021-06-18 15:14:11 -07:00
LICM.cpp Strip undef implying attributes when moving calls 2021-07-27 10:57:05 -04:00
LoopAccessAnalysisPrinter.cpp
…
LoopBoundSplit.cpp [LoopBoundSplit] Ignore phi node which is not scevable 2021-06-09 09:44:36 +01:00
LoopDataPrefetch.cpp [NFCI] Move DEBUG_TYPE definition below #includes 2021-05-30 17:31:01 +08:00
LoopDeletion.cpp [LoopDeletion] Handle switch in proving that loop exits on first iteration 2021-07-09 18:03:34 +07:00
LoopDistribute.cpp [NewPM] Don't mark AA analyses as preserved 2021-05-18 13:49:03 -07:00
LoopFlatten.cpp [LoopFlatten] Use SCEV and Loop APIs to identify increment and trip count 2021-07-27 08:42:59 +01:00
LoopFuse.cpp [ADT] Remove StatisticBase and make NoopStatistic empty 2021-04-26 16:47:32 -07:00
LoopIdiomRecognize.cpp [LoopIdiom] Transform memmove-like loop into memmove (PR46179) 2021-07-22 13:05:43 +02:00
LoopInstSimplify.cpp
…
LoopInterchange.cpp [LoopInterchange] Check lcssa phis in the inner latch in scenarios of multi-level nested loops 2021-07-16 11:59:20 -04:00
LoopLoadElimination.cpp [NFC] Inline variable to prevent unused variable warning 2021-07-13 09:57:59 -07:00
LoopPassManager.cpp [NewPM] Don't mark AA analyses as preserved 2021-05-18 13:49:03 -07:00
LoopPredication.cpp [BPI] Improve static heuristics for "cold" paths. 2020-12-23 22:47:36 +07:00
LoopRerollPass.cpp [LoopReroll] Add an extra defensive check to avoid SCEV assertion. 2021-07-13 12:17:09 -07:00
LoopRotation.cpp [LoopRotate] Don't split loop pass manager 2021-04-08 22:05:18 +02:00
LoopSimplifyCFG.cpp [DominatorTree] Add support for mixed pre/post CFG views. 2021-01-06 14:53:09 -08:00
LoopSink.cpp [llvm] Use set_is_subset (NFC) 2021-02-28 10:59:20 -08:00
LoopStrengthReduce.cpp Handle unused variable when assertions are disabled 2021-07-27 15:43:06 +02:00
LoopUnrollAndJamPass.cpp LoopUnrollAndJamPass.cpp - remove unused <vector> include. NFCI. 2021-06-13 14:06:32 +01:00
LoopUnrollPass.cpp [LoopUnroll] Don't modify TripCount/TripMultiple in computeUnrollCount() (NFCI) 2021-06-21 21:34:17 +02:00
LoopUnswitch.cpp Add a subclass of IntrinsicInst for llvm.assume [nfc] 2021-04-06 11:16:22 -07:00
LoopVersioningLICM.cpp
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LowerAtomic.cpp [NVPTX] Enable lowering of atomics on local memory 2021-04-26 20:12:12 -04:00
LowerConstantIntrinsics.cpp [NewPM] Don't mark AA analyses as preserved 2021-05-18 13:49:03 -07:00
LowerExpectIntrinsic.cpp [TargetTransformInfo] move branch probability query from TargetLoweringInfo 2021-03-22 15:55:34 -04:00
LowerGuardIntrinsic.cpp
…
LowerMatrixIntrinsics.cpp [Matrix] Fix -Wunused-variable in -DLLVM_ENABLE_ASSERTIONS=off build after D106457. NFC 2021-07-22 11:33:02 -07:00
LowerWidenableCondition.cpp
…
MakeGuardsExplicit.cpp
…
MemCpyOptimizer.cpp Revert "[MemCpyOpt] Enable memcpy optimizations unconditionally." 2021-07-19 14:27:41 -07:00
MergeICmps.cpp [MergeICmps] Collect block instructions once (NFC) 2021-07-26 18:07:20 +02:00
MergedLoadStoreMotion.cpp [NewPM] Don't mark AA analyses as preserved 2021-05-18 13:49:03 -07:00
NaryReassociate.cpp [NARY] Don't optimize min/max if there are side uses (part2) 2021-04-30 19:02:02 +07:00
NewGVN.cpp [NewPM] Don't mark AA analyses as preserved 2021-05-18 13:49:03 -07:00
PartiallyInlineLibCalls.cpp [PartiallyInlineLibCalls] Disable sqrt expansion for strictfp. 2021-06-17 14:15:12 -07:00
PlaceSafepoints.cpp [Transforms] Use llvm::append_range (NFC) 2020-12-27 09:57:29 -08:00
Reassociate.cpp [NewPM] Don't mark AA analyses as preserved 2021-05-18 13:49:03 -07:00
Reg2Mem.cpp
…
RewriteStatepointsForGC.cpp [RS4GC] Use one DVCache for both inlineGetBaseAndOffset() and insertParsePoints() 2021-07-12 18:13:00 +07:00
SCCP.cpp [Local] Do not introduce a new `llvm.trap` before `unreachable` 2021-07-26 23:33:36 -05:00
SROA.cpp [SROA] avoid crash on memset with constant expression length 2021-07-21 15:20:28 -04:00
Scalar.cpp Add jump-threading optimization for deterministic finite automata 2021-07-27 14:34:04 -04:00
ScalarizeMaskedMemIntrin.cpp [ScalarizeMaskedMemIntrin][SelectionDAGBuilder] Use the element type to calculate alignment for gather/scatter when alignment operand is 0. 2021-07-01 19:08:47 -07:00
Scalarizer.cpp Update @llvm.powi to handle different int sizes for the exponent 2021-06-17 09:38:28 +02:00
SeparateConstOffsetFromGEP.cpp SeparateConstOffsetFromGEP::lowerToSingleIndexGEPs - don't use dyn_cast_or_null. NFCI. 2020-12-15 17:27:25 +00:00
SimpleLoopUnswitch.cpp [SimpleLoopUnswitch] Don't non-trivially unswitch loops with catchswitch exits 2021-07-14 14:07:28 -07:00
SimplifyCFGPass.cpp [SimplifyCFG] Tail-merging all blocks with `resume` terminator 2021-06-24 21:25:06 +03:00
Sink.cpp [CSSPGO] Unblock optimizations with pseudo probe instrumentation part 2. 2021-04-26 16:52:33 -07:00
SpeculativeExecution.cpp [NewPM] Don't mark AA analyses as preserved 2021-05-18 13:49:03 -07:00
StraightLineStrengthReduce.cpp [Transforms/Scalar] Use range-based for loops (NFC) 2021-02-04 21:18:05 -08:00
StructurizeCFG.cpp [Scalar] Use range-based for loops (NFC) 2021-02-25 19:54:38 -08:00
TailRecursionElimination.cpp [TRE] Reland: allow TRE for non-capturing calls. 2021-05-25 11:35:48 +03:00
WarnMissedTransforms.cpp
…