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llvm-mirror/lib/Analysis
Florian Hahn 6ecdafe314 [ValueTracking] Fix recurrence detection to check both PHI operands.
Summary:
Currently we fail to compute known bits for recurrences where the
first incoming value is the start value of the recurrence.

Instead of exiting the loop when the first incoming value is not
the step of the recurrence, continue to check the second incoming
value.

The original code uses a loop to handle both cases, but incorrectly
exits instead of continuing.

Reviewers: lebedev.ri, spatel, nikic

Reviewed By: lebedev.ri

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66216

llvm-svn: 369088
2019-08-16 09:15:02 +00:00
..
AliasAnalysis.cpp [AliasAnalysis/NewPassManager] Invalidate AAManager less often. 2019-04-30 22:15:47 +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/MSSA] Add promotion to scalars by building an AliasSetTracker with MemorySSA. 2019-02-06 20:25:17 +00:00
Analysis.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
AssumptionCache.cpp [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
BasicAliasAnalysis.cpp [ValueTracking] Look through ptrmask intrinsics during getUnderlyingObject. 2019-08-15 18:39:56 +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] Look through bitcasts in calcZeroHeuristic 2019-02-15 11:50:21 +00:00
CallGraph.cpp [CallGraph] Refine call graph for indirect calls with !callees metadata 2019-08-15 17:47:53 +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 [ValueTracking] Add MustPreserveNullness arg to functions analyzing calls. (NFC) 2019-08-15 12:13:02 +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 [AliasAnalysis] Second prototype to cache BasicAA / anyAA state. 2019-03-22 17:22:19 +00:00
CFLGraph.h [CFLGraph] Add support for unary fneg instruction. 2019-06-06 19:21:23 +00:00
CFLSteensAliasAnalysis.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CGSCCPassManager.cpp [CallGraph] Refine call graph for indirect calls with !callees metadata 2019-08-15 17:47:53 +00:00
CMakeLists.txt Title: Loop Cache Analysis 2019-08-09 13:56:29 +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 [SCCP] Update condition to avoid overflow. 2019-07-31 18:22:22 +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
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
DivergenceAnalysis.cpp [DivergenceAnalysis] Add methods for querying divergence at use 2019-07-29 10:22:09 +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
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
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 Add "const" in GetUnderlyingObjects. NFC 2019-04-24 06:55:50 +00:00
GuardUtils.cpp [WideableCond] Fix a nasty bug in detection of "explicit guards" 2019-04-02 16:51:43 +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 [InstCombine] fold cmp+select using select operand equivalence 2019-08-02 17:39:32 +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
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
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 [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
LazyCallGraph.cpp [CallGraph] Refine call graph for indirect calls with !callees metadata 2019-08-15 17:47:53 +00:00
LazyValueInfo.cpp [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
LegacyDivergenceAnalysis.cpp [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
Lint.cpp [Lint] Permit aliasing noalias readonly arguments 2019-04-23 23:43:47 +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
Loads.cpp [ValueTracking] Add MustPreserveNullness arg to functions analyzing calls. (NFC) 2019-08-15 12:13:02 +00:00
LoopAccessAnalysis.cpp [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
LoopAnalysisManager.cpp Only passes that preserve MemorySSA must mark it as preserved. 2019-06-11 18:27:49 +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 OpaquePtr: switch to GlobalValue::getValueType in a few places. NFC. 2019-07-11 13:13:02 +00:00
MemoryDependenceAnalysis.cpp [MemDep] allow to select block-scan-limit when constructing MemoryDependenceAnalysis 2019-08-10 01:23:38 +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] Remove restrictive asserts. 2019-08-15 21:20:08 +00:00
MemorySSAUpdater.cpp [IR] Value: add replaceUsesWithIf() utility 2019-08-01 12:32:08 +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 [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +00:00
MustExecute.cpp [MustExecute] Improve MustExecute to correctly handle loop nest 2019-05-27 13:57:28 +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] Rename getMaxBackedgeTakenCount to getConstantMaxBackedgeTakenCount [NFC] 2019-08-14 21:58:13 +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 Hide two unused debugging methods, NFCI. 2019-03-01 17:15:21 +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] Bug fix: Use IPD outside the loop as divergence bound 2019-04-18 16:17:35 +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 [AMDGPU] Printf runtime binding pass 2019-08-12 17:12:29 +00:00
TargetTransformInfo.cpp InferAddressSpaces: Move target intrinsic handling to TTI 2019-08-14 18:13:00 +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] Fix recurrence detection to check both PHI operands. 2019-08-16 09:15:02 +00:00
VectorUtils.cpp [LV] Avoid building interleaved group in presence of WAW dependency 2019-08-02 06:31:50 +00:00

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))

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