llvm-project/llvm/lib/Analysis
David Green 4511f3fa86 [SCEV] Ensure that isHighCostExpansion takes into account what is being divided
A SCEV is not low-cost just because you can divide it by a power of 2. We need to also
check what we are dividing to make sure it too is not a high-code expansion. This helps
to not expand the exit value of certain loops, helping not to bloat the code.

The change in no-iv-rewrite.ll is reverting back to what it was testing before rL194116,
and looks a lot like the other tests in replace-loop-exit-folds.ll.

Differential Revision: https://reviews.llvm.org/D58435

llvm-svn: 355393
2019-03-05 12:12:18 +00:00
..
AliasAnalysis.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +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 [CodeExtractor] Update function's assumption cache after extracting blocks from it 2019-02-08 06:55:18 +00:00
BasicAliasAnalysis.cpp [BasicAA] Cache nonEscapingLocalObjects for alias() calls. 2019-02-05 23:52:08 +00:00
BlockFrequencyInfo.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
BlockFrequencyInfoImpl.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
BranchProbabilityInfo.cpp [BPI] Look through bitcasts in calcZeroHeuristic 2019-02-15 11:50:21 +00:00
CFG.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CFGPrinter.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CFLAndersAliasAnalysis.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CFLGraph.h Move CFLGraph and the AA summary code over to the new `CallBase` 2019-02-11 09:25:41 +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 Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CMakeLists.txt Move DomTreeUpdater from IR to Analysis 2019-02-06 02:52:52 +00:00
CallGraph.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
CallGraphSCCPass.cpp Fix IR/Analysis layering issue with OptBisect 2019-02-28 04:00:55 +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 Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +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 [CallSite removal] Migrate ConstantFolding APIs and implementation to 2019-02-11 07:51:44 +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 [DA][NewPM] Handle transitive dependencies in the new-pm version of DA 2019-02-03 12:25:41 +00:00
DivergenceAnalysis.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
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 [NFC] fix trivial typos in comments 2019-02-05 08:30:48 +00:00
GuardUtils.cpp [NFC] Add function to parse widenable conditional branches 2019-01-22 11:21:32 +00:00
IVDescriptors.cpp PHI nodes are not `FPMathOperator` s 2019-03-05 01:15:08 +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 Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
InlineCost.cpp Revert "[INLINER] allow inlining of address taken blocks" 2019-02-14 23:42:21 +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] remove zero-shift-guard fold for general funnel shift 2019-02-26 18:26:56 +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
IteratedDominanceFrontier.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 Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
LazyCallGraph.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
LazyValueInfo.cpp [NFC] fix trivial typos in comments 2019-02-05 08:30:48 +00:00
LegacyDivergenceAnalysis.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
Lint.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
Loads.cpp [Analysis] Fix isSafeToLoadUnconditionally handling of volatile. 2019-01-24 21:31:13 +00:00
LoopAccessAnalysis.cpp [NFC] fix trivial typos in comments 2019-02-05 08:30:48 +00:00
LoopAnalysisManager.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
LoopInfo.cpp Refactor setAlreadyUnrolled() and setAlreadyVectorized(). 2019-02-11 19:45:44 +00:00
LoopPass.cpp Fix IR/Analysis layering issue with OptBisect 2019-02-28 04:00:55 +00:00
LoopUnrollAnalyzer.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +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 Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
MemoryBuiltins.cpp Add a 'dynamic' parameter to the objectsize intrinsic 2019-01-30 20:34:35 +00:00
MemoryDependenceAnalysis.cpp [NFC] Fix typos: preceeding -> preceding 2019-02-23 01:28:32 +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 verifyClobberSanity. 2019-02-11 19:51:21 +00:00
MemorySSAUpdater.cpp [MemorySSA] Make insertDef insert corresponding phi nodes. 2019-02-27 22:20:22 +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 [ThinLTO] Add option to dump per-module summary dot graph 2019-01-28 23:43:26 +00:00
MustExecute.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ObjCARCAliasAnalysis.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +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 Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
OptimizationRemarkEmitter.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
OrderedBasicBlock.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
OrderedInstructions.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +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] Context sensitive PGO (part 2) 2019-02-28 19:55:07 +00:00
PtrUseVisitor.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +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 Fix IR/Analysis layering issue with OptBisect 2019-02-28 04:00:55 +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] Handle case where MaxBECount is less precise than ExactBECount for OR. 2019-03-02 02:31:44 +00:00
ScalarEvolutionAliasAnalysis.cpp Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +00:00
ScalarEvolutionExpander.cpp [SCEV] Ensure that isHighCostExpansion takes into account what is being divided 2019-03-05 12:12:18 +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 Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +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 Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +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 [TargetLibraryInfo] Update run time support for Windows 2019-02-11 22:12:01 +00:00
TargetTransformInfo.cpp [LSR] Generate cross iteration indexes 2019-02-07 13:32:54 +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 Update the file headers across all of the LLVM projects in the monorepo 2019-01-19 08:50:56 +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] do not try to peek through bitcasts in computeKnownBitsFromAssume() 2019-03-03 18:59:33 +00:00
VectorUtils.cpp [Vectorizer] Add vectorization support for fixed smul/umul intrinsics 2019-02-25 15:42:02 +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))

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