llvm-project/llvm/lib/Analysis
Florian Hahn f0c2a5af76 [LV] Generalize conditions for sinking instrs for first order recurrences.
If the recurrence PHI node has a single user, we can sink any
instruction without side effects, given that all users are dominated by
the instruction computing the incoming value of the next iteration
('Previous'). We can sink instructions that may cause traps, because
that only causes the trap to occur later, but not on any new paths.

With the relaxed check, we also have to make sure that we do not have a
direct cycle (meaning PHI user == 'Previous), which indicates a
reduction relation, which potentially gets missed by
ReductionDescriptor.

As follow-ups, we can also sink stores, iff they do not alias with
other instructions we move them across and we could also support sinking
chains of instructions and multiple users of the PHI.

Fixes PR43398.

Reviewers: hsaito, dcaballe, Ayal, rengolin

Reviewed By: Ayal

Differential Revision: https://reviews.llvm.org/D69228
2019-11-02 22:08:27 +01:00
..
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 Fix: Actually erase remove the elements from AssumeHandles 2019-10-02 17:35:06 +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 [SVFS] Vector Function ABI demangling. 2019-09-19 17:47:32 +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] Fold constant calls to log2() 2019-09-30 20:53:23 +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 [DDG] Data Dependence Graph - Root Node 2019-10-01 19:32:42 +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 [DDG] Data Dependence Graph - Root Node 2019-10-01 19:32:42 +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 [LV] Generalize conditions for sinking instrs for first order recurrences. 2019-11-02 22:08:27 +01:00
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 [PGO][PGSO] TargetLowering/TargetTransformationInfo/SwitchLoweringUtils part. 2019-10-31 13:22:56 -07:00
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 [ValueTracking] Allow context-sensitive nullness check for non-pointers 2019-10-31 14:37:38 -05:00
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 Second attempt to add iterator_range::empty() 2019-10-07 18:14:24 +00:00
LazyValueInfo.cpp Fix MSVC "switch statement contains 'default' but no 'case' labels" warning. NFCI. 2019-10-24 13:40:13 -07:00
LegacyDivergenceAnalysis.cpp Remove an unnecessary cast. NFC. 2019-10-02 08:56:33 +00:00
Lint.cpp Change TargetLibraryInfo analysis passes to always require Function 2019-09-07 03:09:36 +00:00
Loads.cpp [Alignment][NFC] Finish transition for `Loads` 2019-10-21 15:10:26 +00:00
LoopAccessAnalysis.cpp LoopAccessAnalysis isConsecutiveAccess() - silence static analyzer dyn_cast<SCEVConstant> null dereference warning. NFCI. 2019-10-02 13:08:56 +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 [LOOPGUARD] Remove asserts in getLoopGuardBranch 2019-10-06 16:39:43 +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 [Alignment][NFC] Finish transition for `Loads` 2019-10-21 15:10:26 +00:00
MemoryBuiltins.cpp [Alignment][NFC] Remove unneeded llvm:: scoping on Align types 2019-09-27 12:54:21 +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 tryOptimizePhi - assert that we've found a DefChainEnd. NFCI. 2019-10-02 13:09:04 +00:00
MemorySSAUpdater.cpp [MemorySSA] Update Phi simplification. 2019-10-10 23:27:21 +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 [FIX] Make LSan happy by *not* leaking memory 2019-10-31 12:16:54 -05:00
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 [PGO][PGSO] ProfileSummary changes. 2019-09-24 22:17:51 +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] Expose and use maximum constant exit counts for individual loop exits 2019-10-24 19:07:33 -07:00
ScalarEvolutionAliasAnalysis.cpp [AliasAnalysis] Second prototype to cache BasicAA / anyAA state. 2019-03-22 17:22:19 +00:00
ScalarEvolutionExpander.cpp [SCEV] Removing deprecated comment in ScalarEvolutionExpander 2019-10-18 13:33:45 +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 [PGO][PGSO] TargetLowering/TargetTransformationInfo/SwitchLoweringUtils part. 2019-10-31 13:22:56 -07:00
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 Reland: Dead Virtual Function Elimination 2019-10-17 09:58:57 +00:00
VFABIDemangling.cpp [SVFS] Vector Function ABI demangling. 2019-09-19 17:47:32 +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] Allow context-sensitive nullness check for non-pointers 2019-10-31 14:37:38 -05:00
VectorUtils.cpp [Alignment][NFC] Make VectorUtils uas llvm::Align 2019-10-10 12:35:04 +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))

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