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Xing Xue 3860aad6e7 [MustExecute] Improve MustExecute to correctly handle loop nest 
Summary:
for.outer:
  br for.inner
for.inner:
  LI <loop invariant load instruction>
for.inner.latch:
  br for.inner, for.outer.latch
for.outer.latch:
  br for.outer, for.outer.exit

LI is a loop invariant load instruction that post dominate for.outer, so LI should be able to move out of the loop nest. However, there is a bug in allLoopPathsLeadToBlock().

Current algorithm of allLoopPathsLeadToBlock()

  1. get all the transitive predecessors of the basic block LI belongs to (for.inner) ==> for.outer, for.inner.latch
  2. if any successors of any of the predecessors are not for.inner or for.inner's predecessors, then return false
  3. return true

Although for.inner.latch is for.inner's predecessor, but for.inner dominates for.inner.latch, which means if for.inner.latch is ever executed, for.inner should be as well. It should not return false for cases like this.

Author: Whitney (committed by xingxue)

Reviewers: kbarton, jdoerfert, Meinersbur, hfinkel, fhahn

Reviewed By: jdoerfert

Subscribers: hiraditya, jsji, llvm-commits, etiotto, bmahjour

Tags: #LLVM

Differential Revision: https://reviews.llvm.org/D62418

llvm-svn: 361762
2019-05-27 13:57:28 +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
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
Add an optional list of blocks to avoid when looking for a path in isPotentiallyReachable.
2019-04-02 01:05:48 +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
[CallSite removal] Move the legacy PM, call graph, and some inliner
2019-04-19 05:59:42 +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
Add an optional list of blocks to avoid when looking for a path in isPotentiallyReachable.
2019-04-02 01:05:48 +00:00
CFG.cpp
An unreachable block may have a route to a reachable block, don't fast-path return that it can't.
2019-04-04 23:09:40 +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
[AliasAnalysis] Second prototype to cache BasicAA / anyAA state.
2019-03-22 17:22:19 +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
[NewPM] Fix a nasty bug with analysis invalidation in the new PM.
2019-03-28 00:51:36 +00:00
CMakeLists.txt
Move DomTreeUpdater from IR to Analysis
2019-02-06 02:52:52 +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
Add FNeg IR constant folding support
2019-05-05 16:07:09 +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
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
Update the file headers across all of the LLVM projects in the monorepo
2019-01-19 08:50:56 +00:00
InlineCost.cpp
[INLINER] allow inlining of blockaddresses if sole uses are callbrs
2019-05-20 16:48:09 +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] fold insertelement-of-extractelement
2019-05-24 00:13:58 +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
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
Update the file headers across all of the LLVM projects in the monorepo
2019-01-19 08:50:56 +00:00
LazyCallGraph.cpp
[LCG] Add aliased functions as LCG roots
2019-04-05 18:51:08 +00:00
LazyValueInfo.cpp
[LVI][CVP] Add support for saturating add/sub
2019-05-25 16:44:14 +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
[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
[Analysis] Fix isSafeToLoadUnconditionally handling of volatile.
2019-01-24 21:31:13 +00:00
LoopAccessAnalysis.cpp
Add "const" in GetUnderlyingObjects. NFC
2019-04-24 06:55:50 +00:00
LoopAnalysisManager.cpp
[MemorySSA] LCSSA preserves MemorySSA.
2019-04-23 20:59:44 +00:00
LoopInfo.cpp
Revert [LOOPINFO] Extend Loop object to add utilities to get the loop bounds, step, induction variable, and guard branch.
2019-05-23 20:53:05 +00:00
LoopPass.cpp
[IR] Refactor attribute methods in Function class (NFC)
2019-04-04 22:40:06 +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
Fix a hang when lowering __builtin_dynamic_object_size
2019-04-10 23:42:11 +00:00
MemoryDependenceAnalysis.cpp
[MemDepAnalysis] Allow caller to pass in an OrderedBasicBlock.
2019-03-28 19:17:31 +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] Check that block is reachable when adding phis.
2019-05-02 23:41:58 +00:00
MemorySSAUpdater.cpp
[MemorySSA] Teach LoopSimplify to preserve MemorySSA.
2019-05-08 17:05:36 +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] Auto-hide prevailing linkonce_odr only when all copies eligible
2019-05-10 20:08:24 +00:00
MustExecute.cpp
[MustExecute] Improve MustExecute to correctly handle loop nest
2019-05-27 13:57:28 +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
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
Recommit "[DSE] Preserve basic block ordering using OrderedBasicBlock."
2019-03-29 14:10:24 +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
Add optional arg to profile count getters to filter
2019-04-24 19:51:16 +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
[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] Add explicit representations of umin/smin
2019-05-07 15:28:47 +00:00
ScalarEvolutionAliasAnalysis.cpp
[AliasAnalysis] Second prototype to cache BasicAA / anyAA state.
2019-03-22 17:22:19 +00:00
ScalarEvolutionExpander.cpp
[SCEV] Suppress hoisting insertion point of binops when unsafe
2019-05-08 18:50:07 +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
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
[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
Add Triple::isPPC64()
2019-05-16 08:31:22 +00:00
TargetTransformInfo.cpp
[ARM] Implement TTI::getMemcpyCost
2019-04-30 10:28:50 +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
[ValueTracking] Base computeOverflowForUnsignedMul() on ConstantRange code; NFCI
2019-05-26 13:22:01 +00:00
VectorUtils.cpp
Consolidate existing utilities for interpreting vector predicate maskes [NFC]
2019-04-25 02:30:17 +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))

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