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History

JF Bastien f4f5b32f44 NFC: make AtomicOrdering an enum class Summary: In the context of http://wg21.link/lwg2445 C++ uses the concept of 'stronger' ordering but doesn't define it properly. This should be fixed in C++17 barring a small question that's still open. The code currently plays fast and loose with the AtomicOrdering enum. Using an enum class is one step towards tightening things. I later also want to tighten related enums, such as clang's AtomicOrderingKind (which should be shared with LLVM as a 'C++ ABI' enum). This change touches a few lines of code which can be improved later, I'd like to keep it as NFC for now as it's already quite complex. I have related changes for clang. As a follow-up I'll add: bool operator<(AtomicOrdering, AtomicOrdering) = delete; bool operator>(AtomicOrdering, AtomicOrdering) = delete; bool operator<=(AtomicOrdering, AtomicOrdering) = delete; bool operator>=(AtomicOrdering, AtomicOrdering) = delete; This is separate so that clang and LLVM changes don't need to be in sync. Reviewers: jyknight, reames Subscribers: jyknight, llvm-commits Differential Revision: http://reviews.llvm.org/D18775 llvm-svn: 265602		2016-04-06 21:19:33 +00:00
..
AliasAnalysis.cpp	NFC: make AtomicOrdering an enum class	2016-04-06 21:19:33 +00:00
AliasAnalysisEvaluator.cpp
AliasSetTracker.cpp	NFC: make AtomicOrdering an enum class	2016-04-06 21:19:33 +00:00
Analysis.cpp
AssumptionCache.cpp
BasicAliasAnalysis.cpp
BlockFrequencyInfo.cpp
BlockFrequencyInfoImpl.cpp
BranchProbabilityInfo.cpp
CallGraph.cpp
CallGraphSCCPass.cpp
CallPrinter.cpp
CaptureTracking.cpp
CFG.cpp
CFGPrinter.cpp
CFLAliasAnalysis.cpp	[CFLAA] Fix PR27213; incorrect tagging of args/globals	2016-04-05 21:40:45 +00:00
CGSCCPassManager.cpp
CMakeLists.txt
CodeMetrics.cpp
ConstantFolding.cpp	Fix Clang-tidy modernize-deprecated-headers warnings in some files; other minor fixes.	2016-03-28 17:40:08 +00:00
CostModel.cpp
Delinearization.cpp
DemandedBits.cpp
DependenceAnalysis.cpp	[DependenceAnalysis] Check if result of getConstantPart is null	2016-04-04 18:13:18 +00:00
DivergenceAnalysis.cpp
DominanceFrontier.cpp
DomPrinter.cpp
EHPersonalities.cpp
GlobalsModRef.cpp
InlineCost.cpp
InstCount.cpp
InstructionSimplify.cpp	Minor code cleanups. NFC.	2016-04-05 21:14:31 +00:00
Interval.cpp
IntervalPartition.cpp
IteratedDominanceFrontier.cpp
IVUsers.cpp
LazyCallGraph.cpp
LazyValueInfo.cpp
Lint.cpp
LLVMBuild.txt
Loads.cpp
LoopAccessAnalysis.cpp	Revert r265535 until we know how we can fix the bots	2016-04-06 14:06:32 +00:00
LoopInfo.cpp	IR: Reserve an MDKind for !llvm.loop; NFC	2016-03-25 00:35:38 +00:00
LoopPass.cpp
LoopPassManager.cpp
LoopUnrollAnalyzer.cpp
MemDepPrinter.cpp
MemDerefPrinter.cpp
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp	NFC: make AtomicOrdering an enum class	2016-04-06 21:19:33 +00:00
MemoryLocation.cpp
ModuleDebugInfoPrinter.cpp
ObjCARCAliasAnalysis.cpp
ObjCARCAnalysisUtils.cpp
ObjCARCInstKind.cpp
OrderedBasicBlock.cpp
PHITransAddr.cpp
PostDominators.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	Revert r265535 until we know how we can fix the bots	2016-04-06 14:06:32 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	Revert r265535 until we know how we can fix the bots	2016-04-06 14:06:32 +00:00
ScalarEvolutionNormalization.cpp
ScopedNoAliasAA.cpp
SparsePropagation.cpp
StratifiedSets.h
TargetLibraryInfo.cpp	[NVPTX] Infer __nvvm_reflect as nounwind, readnone	2016-03-31 21:29:57 +00:00
TargetTransformInfo.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	Mark some FP intrinsics as safe to speculatively execute	2016-04-03 12:30:46 +00:00
VectorUtils.cpp	[SLPVectorizer] Vectorizing the libm sqrt to llvm's sqrt intrinsic requires nnan	2016-04-06 07:04:53 +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))

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