llvm/Analysis at 0eebc2900c15aa8e0bf290e12dcf9e247b35cfc6 - llvm

RPCSX/llvm

mirror of https://github.com/RPCSX/llvm.git synced 2024-12-12 14:17:59 +00:00

History

Sanjay Patel 0eebc2900c [InstSimplify] add folds for or-of-casted-icmps The sibling folds for 'and' with casts were added with https://reviews.llvm.org/rL273200. This is a preliminary step for adding the 'or' variants for the folds added with https://reviews.llvm.org/rL301260. The reason for the strange form with constant LHS in the 1st test is because there's another missing fold in that case for the inverted predicate. That should be fixed when we add the ConstantRange functionality for 'or-of-icmps' that already exists for 'and-of-icmps'. I'm hoping to share more code for the and/or cases, so we won't have these differences. This will allow us to remove code from InstCombine. It's also possible that we can remove some code here in InstSimplify. I think we have some duplicated folds because patterns are not matched in a general way. Differential Revision: https://reviews.llvm.org/D32876 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302189 91177308-0d34-0410-b5e6-96231b3b80d8		2017-05-04 19:51:34 +00:00
..
AliasAnalysis.cpp
AliasAnalysisEvaluator.cpp
AliasAnalysisSummary.cpp
AliasAnalysisSummary.h
AliasSetTracker.cpp
Analysis.cpp
AssumptionCache.cpp
BasicAliasAnalysis.cpp
BlockFrequencyInfo.cpp
BlockFrequencyInfoImpl.cpp
BranchProbabilityInfo.cpp
CallGraph.cpp
CallGraphSCCPass.cpp
CallPrinter.cpp
CaptureTracking.cpp
CFG.cpp
CFGPrinter.cpp
CFLAndersAliasAnalysis.cpp
CFLGraph.h	[IR] Abstract away ArgNo+1 attribute indexing as much as possible	2017-05-03 18:17:31 +00:00
CFLSteensAliasAnalysis.cpp
CGSCCPassManager.cpp
CMakeLists.txt
CodeMetrics.cpp
ConstantFolding.cpp	[KnownBits] Add methods for determining if KnownBits is a constant value	2017-05-03 23:12:29 +00:00
CostModel.cpp
Delinearization.cpp
DemandedBits.cpp
DependenceAnalysis.cpp
DivergenceAnalysis.cpp
DominanceFrontier.cpp
DomPrinter.cpp
EHPersonalities.cpp
GlobalsModRef.cpp
IndirectCallPromotionAnalysis.cpp
InlineCost.cpp	Refactor callsite cost computation into a helper function /NFC	2017-05-02 05:38:41 +00:00
InstCount.cpp
InstructionSimplify.cpp	[InstSimplify] add folds for or-of-casted-icmps	2017-05-04 19:51:34 +00:00
Interval.cpp
IntervalPartition.cpp
IteratedDominanceFrontier.cpp
IVUsers.cpp
LazyBlockFrequencyInfo.cpp
LazyBranchProbabilityInfo.cpp
LazyCallGraph.cpp
LazyValueInfo.cpp
Lint.cpp
LLVMBuild.txt
Loads.cpp
LoopAccessAnalysis.cpp
LoopAnalysisManager.cpp
LoopInfo.cpp
LoopPass.cpp
LoopUnrollAnalyzer.cpp
MemDepPrinter.cpp
MemDerefPrinter.cpp
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp
MemoryLocation.cpp
MemorySSA.cpp
MemorySSAUpdater.cpp
ModuleDebugInfoPrinter.cpp
ModuleSummaryAnalysis.cpp	Re-apply r302108, "IR: Use pointers instead of GUIDs to represent edges in the module summary. NFCI."	2017-05-04 18:03:25 +00:00
ObjCARCAliasAnalysis.cpp
ObjCARCAnalysisUtils.cpp
ObjCARCInstKind.cpp
OptimizationDiagnosticInfo.cpp
OrderedBasicBlock.cpp
PHITransAddr.cpp
PostDominators.cpp
ProfileSummaryInfo.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	Fix a typo.	2017-05-04 17:42:34 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
ScalarEvolutionNormalization.cpp
ScopedNoAliasAA.cpp
SparsePropagation.cpp
StratifiedSets.h
TargetLibraryInfo.cpp
TargetTransformInfo.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp
TypeMetadataUtils.cpp
ValueTracking.cpp	[ValueTracking] Remove handling for BitWidth being 0 in ComputeSignBit and isKnownNonZero.	2017-05-03 22:25:19 +00:00
VectorUtils.cpp

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))

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