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llvm-project/llvm/lib/Analysis
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Philip Reames 34f68253ca [SCEV] Expose and use maximum constant exit counts for individual loop exits 
We were already going to all of the trouble of computing maximum constant exit counts for each loop exit, we might as well expose them through the API.  The change in IndVars is mostly to demonstrate that the wired up code works, but it als very slightly strengthens the transform.  The strengthened case is rather narrow though: it requires one exactly analyzeable exit, one imprecisely analyzeable exit (with the upper bound less than the precise one), and one unanalyzeable exit.  I coudn't construct a reasonably stable test case.

This does increase the memory usage of the BackedgeTakenCount by a factor of 2 in the worst case.

I also noticed the loop in IndVars is O(#Exits ^ 2).  This doesn't change with this patch.  A future patch will cache this result inside of SCEV to avoid requering.
2019-10-24 19:07:33 -07:00
..
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
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
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
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
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
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
IndirectCallPromotionAnalysis.cpp
[llvm] Migrate llvm::make_unique to std::make_unique
2019-08-15 15:54:37 +00:00
InlineCost.cpp
[SVE][IR] Scalable Vector size queries and IR instruction support
2019-10-08 12:53:54 +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] Simplify fma multiplication to nan for undef or nan operands.
2019-10-02 12:32:52 +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
[IR] allow fast-math-flags on phi of FP values (2nd try)
2019-09-25 14:35:02 +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
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
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
[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
[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
[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
[NFC][TTI] Add Alignment for isLegalMasked[Load/Store]
2019-10-14 10:00:21 +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
Reland: Dead Virtual Function Elimination
2019-10-17 09:58:57 +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
[Alignment][NFC] Finish transition for Loads
2019-10-21 15:10:26 +00:00
VectorUtils.cpp
[Alignment][NFC] Make VectorUtils uas llvm::Align
2019-10-10 12:35:04 +00:00
VFABIDemangling.cpp
[SVFS] Vector Function ABI demangling.
2019-09-19 17:47:32 +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))

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