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Simon Pilgrim 8ee477a2ab [InstSimplify] SimplifyICmpInst - icmp eq/ne %X, undef -> undef As discussed on PR41125 and D59363, we have a mismatch between icmp eq/ne cases with an undef operand: When the other operand is constant we fold to undef (handled in ConstantFoldCompareInstruction) When the other operand is non-constant we fold to a bool constant based on isTrueWhenEqual (handled in SimplifyICmpInst). Neither is really wrong, but this patch changes the logic in SimplifyICmpInst to consistently fold to undef. The NewGVN test change is annoying (as with most heavily reduced tests) but AFAICT I have kept the purpose of the test based on rL291968. Differential Revision: https://reviews.llvm.org/D59541 llvm-svn: 356456		2019-03-19 14:08:23 +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	[CFLAnders] Fix typo in comment; NFC	2019-03-08 19:28:55 +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	Reland "Relax constraints for reduction vectorization"	2019-03-12 01:31:44 +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] SimplifyICmpInst - icmp eq/ne %X, undef -> undef	2019-03-19 14:08:23 +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	[IDF] Delete a redundant J-edge test	2019-03-07 11:42:59 +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 redundant walker assignment [NFC].	2019-03-14 18:45:17 +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] Restructure AliasSummary to contain ValueInfo of Aliasee	2019-03-15 15:11:38 +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	[RegionPass] Fix forgotten "!".	2019-03-08 21:03:06 +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] Use depth limit for trunc analysis	2019-03-12 18:28:05 +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] Guard movement of insertion point for loop-invariants	2019-03-18 18:52:35 +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	[SelectionDAG] Allow the user to specify a memeq function.	2019-03-08 09:07:45 +00:00
TargetTransformInfo.cpp	[TTI] Enable analysis of clib functions in getIntrinsicCosts. NFCI.	2019-03-12 09:48:02 +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	Revert "[ValueTracking][InstSimplify] Support min/max selects in computeConstantRange()"	2019-03-18 22:26:27 +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))

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