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llvm-mirror/lib/Analysis
Roman Lebedev 3ef0797917 [ConstantFolding] Fix 'undef' folding for @llvm.[us]{add,sub}.with.overflow ops (PR43188)
As we have already established/fixed in
  https://bugs.llvm.org/show_bug.cgi?id=42209
  https://reviews.llvm.org/D63065
  https://reviews.llvm.org/rL363522
the InstSimplify handling for @llvm.with.overflow ops with undefs
is correct. Therefore if ConstantFolding produces different results,
then it is wrong.

This duplication of code hints at the need for some refactoring,
but for now address the brokenness of ConstantFolding by
copying the known-good handling from rL363522.

Fixes https://bugs.llvm.org/show_bug.cgi?id=43188

llvm-svn: 370608
2019-09-01 11:56:52 +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 [MustExec] Add a generic "must-be-executed-context" explorer 2019-08-23 15:17:27 +00:00
AssumptionCache.cpp AssumptionCache: remove old affected values after RAUW. 2019-08-16 09:34:27 +00:00
BasicAliasAnalysis.cpp [BasicAA] Use dereferenceability to reason about aliasing 2019-08-23 17:56:10 +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 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 [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 Revert "[CallGraph] Refine call graph for indirect calls with !callees metadata" 2019-08-16 10:59:18 +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 [ConstantFolding] Fix 'undef' folding for @llvm.[us]{add,sub}.with.overflow ops (PR43188) 2019-09-01 11:56:52 +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 Allow replaceAndRecursivelySimplify to list unsimplified visitees. 2019-08-29 13:22:30 +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 Revert "[CallGraph] Refine call graph for indirect calls with !callees metadata" 2019-08-16 10:59:18 +00:00
LazyValueInfo.cpp [LVI] Extract solveBlockValueExtractValue(); NFC 2019-08-31 09:58:50 +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 [NFC] Assert preconditions and merge all users into one codepath in Loads.cpp 2019-08-27 23:36:31 +00:00
LoopAccessAnalysis.cpp [llvm] Migrate llvm::make_unique to std::make_unique 2019-08-15 15:54:37 +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 [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 Annotate return values of allocation functions with dereferenceable_or_null 2019-08-28 08:28:20 +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] Rename all phi entries. 2019-08-30 23:02:53 +00:00
MemorySSAUpdater.cpp [MemorySSA] Fix insertUse. 2019-08-27 00:34:47 +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 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 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] 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 [TLI] Simplify code. NFCI. 2019-08-24 17:30:12 +00:00
TargetTransformInfo.cpp [CostModel] Model all extractvalues as free. 2019-08-29 11:50:30 +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 Refactor isPointerOffset (NFC). 2019-08-19 21:08:04 +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))

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