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Bardia Mahjour db800c267d Data Dependence Graph Basics 
Summary:
This is the first patch in a series of patches that will implement data dependence graph in LLVM. Many of the ideas used in this implementation are based on the following paper:
D. J. Kuck, R. H. Kuhn, D. A. Padua, B. Leasure, and M. Wolfe (1981). DEPENDENCE GRAPHS AND COMPILER OPTIMIZATIONS.
This patch contains support for a basic DDGs containing only atomic nodes (one node for each instruction). The edges are two fold: def-use edges and memory-dependence edges.
The implementation takes a list of basic-blocks and only considers dependencies among instructions in those basic blocks. Any dependencies coming into or going out of instructions that do not belong to those basic blocks are ignored.

The algorithm for building the graph involves the following steps in order:

  1. For each instruction in the range of basic blocks to consider, create an atomic node in the resulting graph.
  2. For each node in the graph establish def-use edges to/from other nodes in the graph.
  3. For each pair of nodes containing memory instruction(s) create memory edges between them. This part of the algorithm goes through the instructions in lexicographical order and creates edges in reverse order if the sink of the dependence occurs before the source of it.

Authored By: bmahjour

Reviewer: Meinersbur, fhahn, myhsu, xtian, dmgreen, kbarton, jdoerfert

Reviewed By: Meinersbur, fhahn, myhsu

Subscribers: ychen, arphaman, simoll, a.elovikov, mgorny, hiraditya, jfb, wuzish, llvm-commits, jsji, Whitney, etiotto

Tag: #llvm

Differential Revision: https://reviews.llvm.org/D65350

llvm-svn: 372238
 		2019-09-18 17:43:45 +00:00
..
AliasAnalysis.cpp Change TargetLibraryInfo analysis passes to always require Function 2019-09-07 03:09:36 +00:00
AliasAnalysisEvaluator.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
AliasAnalysisSummary.cpp Move CFLGraph and the AA summary code over to the new `CallBase` 2019-02-11 09:25:41 +00:00
AliasAnalysisSummary.h Move CFLGraph and the AA summary code over to the new `CallBase` 2019-02-11 09:25:41 +00:00
AliasSetTracker.cpp [LICM/AST] Check if the AliasAny set is removed from the tracker. 2019-09-12 18:09:47 +00:00
Analysis.cpp [MustExec] Add a generic "must-be-executed-context" explorer 2019-08-23 15:17:27 +00:00
AssumptionCache.cpp AssumptionCache: remove old affected values after RAUW. 2019-08-16 09:34:27 +00:00
BasicAliasAnalysis.cpp Change TargetLibraryInfo analysis passes to always require Function 2019-09-07 03:09:36 +00:00
BlockFrequencyInfo.cpp Add optional arg to profile count getters to filter 2019-04-24 19:51:16 +00:00
BlockFrequencyInfoImpl.cpp Add optional arg to profile count getters to filter 2019-04-24 19:51:16 +00:00
BranchProbabilityInfo.cpp [BPI] Adjust the probability for floating point unordered comparison 2019-09-10 17:25:11 +00:00
CFG.cpp Recommit "[GVN] Preserve loop related analysis/canonical forms." 2019-07-31 09:27:54 +00:00
CFGPrinter.cpp Rename F_{None,Text,Append} to OF_{None,Text,Append}. NFC 2019-08-05 05:43:48 +00:00
CFLAndersAliasAnalysis.cpp Change TargetLibraryInfo analysis passes to always require Function 2019-09-07 03:09:36 +00:00
CFLGraph.h [CFLGraph] Add support for unary fneg instruction. 2019-06-06 19:21:23 +00:00
CFLSteensAliasAnalysis.cpp Change TargetLibraryInfo analysis passes to always require Function 2019-09-07 03:09:36 +00:00
CGSCCPassManager.cpp Revert "[CallGraph] Refine call graph for indirect calls with !callees metadata" 2019-08-16 10:59:18 +00:00
CMakeLists.txt Data Dependence Graph Basics 2019-09-18 17:43:45 +00:00
CallGraph.cpp Revert "[CallGraph] Refine call graph for indirect calls with !callees metadata" 2019-08-16 10:59:18 +00:00
CallGraphSCCPass.cpp [CallSite removal] Move the legacy PM, call graph, and some inliner 2019-04-19 05:59:42 +00:00
CallPrinter.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CaptureTracking.cpp [CaptureTracker] Let subclasses provide dereferenceability information 2019-08-19 21:56:38 +00:00
CmpInstAnalysis.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CodeMetrics.cpp Remove `CallSite` from the CodeMetrics analysis, moving it to the new 2019-02-11 09:03:32 +00:00
ConstantFolding.cpp [ConstantFolding] Expand folding of some library functions 2019-09-12 21:23:22 +00:00
CostModel.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
DDG.cpp Data Dependence Graph Basics 2019-09-18 17:43:45 +00:00
Delinearization.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
DemandedBits.cpp [DemandedBits] Remove some redundancy in the work list 2019-03-03 14:50:01 +00:00
DependenceAnalysis.cpp [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
DependenceGraphBuilder.cpp Data Dependence Graph Basics 2019-09-18 17:43:45 +00:00
DivergenceAnalysis.cpp [DivergenceAnalysis] Add methods for querying divergence at use 2019-07-29 10:22:09 +00:00
DomPrinter.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
DomTreeUpdater.cpp [DTU] Refine the interface and logic of applyUpdates 2019-02-22 13:48:38 +00:00
DominanceFrontier.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
EHPersonalities.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
GlobalsModRef.cpp Change TargetLibraryInfo analysis passes to always require Function 2019-09-07 03:09:36 +00:00
GuardUtils.cpp [WideableCond] Fix a nasty bug in detection of "explicit guards" 2019-04-02 16:51:43 +00:00
IVDescriptors.cpp Save the induction binary operator in IVDescriptors for non FP induction variables. 2019-05-14 13:26:36 +00:00
IVUsers.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IndirectCallPromotionAnalysis.cpp [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
InlineCost.cpp [InstSimplify] Rename SimplifyFPUnOp and SimplifyFPBinOp 2019-07-24 12:50:10 +00:00
InstCount.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
InstructionPrecedenceTracking.cpp Make widenable condition transparent for MemoryWriteTracking 2019-02-14 11:10:29 +00:00
InstructionSimplify.cpp [InstSimplify] simplifyUnsignedRangeCheck(): handle few tautological cases (PR43251) 2019-09-14 13:47:27 +00:00
Interval.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
IntervalPartition.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
LLVMBuild.txt Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
LazyBlockFrequencyInfo.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
LazyBranchProbabilityInfo.cpp Change TargetLibraryInfo analysis passes to always require Function 2019-09-07 03:09:36 +00:00
LazyCallGraph.cpp Change TargetLibraryInfo analysis passes to always require Function 2019-09-07 03:09:36 +00:00
LazyValueInfo.cpp [LVI] Look through extractvalue of insertvalue 2019-09-07 12:03:59 +00:00
LegacyDivergenceAnalysis.cpp [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
Lint.cpp Change TargetLibraryInfo analysis passes to always require Function 2019-09-07 03:09:36 +00:00
Loads.cpp [LV] Support invariant addresses in speculation logic 2019-09-12 16:49:10 +00:00
LoopAccessAnalysis.cpp Change TargetLibraryInfo analysis passes to always require Function 2019-09-07 03:09:36 +00:00
LoopAnalysisManager.cpp [LoopPassManager + MemorySSA] Only enable use of MemorySSA for LPMs known to preserve it. 2019-08-21 17:00:57 +00:00
LoopCacheAnalysis.cpp [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
LoopInfo.cpp [LOOPINFO] Introduce the loop guard API. 2019-07-25 16:13:18 +00:00
LoopPass.cpp ftime-trace: Trace loop passes 2019-05-31 10:14:04 +00:00
LoopUnrollAnalyzer.cpp [InstSimplify] Rename SimplifyFPUnOp and SimplifyFPBinOp 2019-07-24 12:50:10 +00:00
MemDepPrinter.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
MemDerefPrinter.cpp OpaquePtr: add Type parameter to Loads analysis API. 2019-07-09 11:35:35 +00:00
MemoryBuiltins.cpp [InstCombine] Annotate strdup with deref_or_null 2019-09-17 10:12:48 +00:00
MemoryDependenceAnalysis.cpp Change TargetLibraryInfo analysis passes to always require Function 2019-09-07 03:09:36 +00:00
MemoryLocation.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
MemorySSA.cpp [MemorySSA] Update MSSA for non-conventional AA. 2019-09-17 16:31:37 +00:00
MemorySSAUpdater.cpp [MemorySSA] Fix phi insertion when inserting a def. 2019-09-17 16:33:35 +00:00
ModuleDebugInfoPrinter.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ModuleSummaryAnalysis.cpp IR. Change strip* family of functions to not look through aliases. 2019-08-22 19:56:14 +00:00
MustExecute.cpp [MustExec] Add a generic "must-be-executed-context" explorer 2019-08-23 15:17:27 +00:00
ObjCARCAliasAnalysis.cpp [AliasAnalysis] Second prototype to cache BasicAA / anyAA state. 2019-03-22 17:22:19 +00:00
ObjCARCAnalysisUtils.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ObjCARCInstKind.cpp [ObjC][ARC] Delete ObjC runtime calls on global variables annotated 2019-06-14 22:06:32 +00:00
OptimizationRemarkEmitter.cpp [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
OrderedBasicBlock.cpp Recommit "[DSE] Preserve basic block ordering using OrderedBasicBlock." 2019-03-29 14:10:24 +00:00
OrderedInstructions.cpp [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
PHITransAddr.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
PhiValues.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
PostDominators.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ProfileSummaryInfo.cpp Cleanup: llvm::bsearch -> llvm::partition_point after r364719 2019-06-30 11:19:56 +00:00
PtrUseVisitor.cpp SROA: Allow eliminating addrspacecasted allocas 2019-06-14 21:38:31 +00:00
README.txt
…
RegionInfo.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
RegionPass.cpp [IR] Refactor attribute methods in Function class (NFC) 2019-04-04 22:40:06 +00:00
RegionPrinter.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ScalarEvolution.cpp [SCEV] Add smin support to getRangeRef 2019-09-12 21:32:27 +00:00
ScalarEvolutionAliasAnalysis.cpp [AliasAnalysis] Second prototype to cache BasicAA / anyAA state. 2019-03-22 17:22:19 +00:00
ScalarEvolutionExpander.cpp [SCEV] Fix for PR42397. SCEVExpander wrongly adds nsw to shl instruction. 2019-07-08 18:03:43 +00:00
ScalarEvolutionNormalization.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ScopedNoAliasAA.cpp [AliasAnalysis] Second prototype to cache BasicAA / anyAA state. 2019-03-22 17:22:19 +00:00
StackSafetyAnalysis.cpp IR. Change strip* family of functions to not look through aliases. 2019-08-22 19:56:14 +00:00
StratifiedSets.h Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
SyncDependenceAnalysis.cpp [SDA] Don't stop divergence propagation at the IPD. 2019-09-18 13:40:22 +00:00
SyntheticCountsUtils.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
TargetLibraryInfo.cpp [TLI][AMDGPU] AMDPAL does not have library functions 2019-09-11 07:26:39 +00:00
TargetTransformInfo.cpp [NFC] remove unused functions 2019-09-16 14:48:58 +00:00
Trace.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
TypeBasedAliasAnalysis.cpp [AliasAnalysis] Second prototype to cache BasicAA / anyAA state. 2019-03-22 17:22:19 +00:00
TypeMetadataUtils.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ValueLattice.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ValueLatticeUtils.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ValueTracking.cpp [ValueTracking] Factor our common speculation suppression logic [NFC] 2019-09-10 21:12:29 +00:00
VectorUtils.cpp InterleavedAccessInfo - Don't dereference a dyn_cast result. NFCI. 2019-09-17 13:25:56 +00:00

README.txt 

Analysis Opportunities:

//===---------------------------------------------------------------------===//

In test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll, the
ScalarEvolution expression for %r is this:

  {1,+,3,+,2}<loop>

Outside the loop, this could be evaluated simply as (%n * %n), however
ScalarEvolution currently evaluates it as

  (-2 + (2 * (trunc i65 (((zext i64 (-2 + %n) to i65) * (zext i64 (-1 + %n) to i65)) /u 2) to i64)) + (3 * %n))

In addition to being much more complicated, it involves i65 arithmetic,
which is very inefficient when expanded into code.

//===---------------------------------------------------------------------===//

In formatValue in test/CodeGen/X86/lsr-delayed-fold.ll,

ScalarEvolution is forming this expression:

((trunc i64 (-1 * %arg5) to i32) + (trunc i64 %arg5 to i32) + (-1 * (trunc i64 undef to i32)))

This could be folded to

(-1 * (trunc i64 undef to i32))

//===---------------------------------------------------------------------===//