llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-11-02 07:11:49 +00:00

History

Bjorn Steinbrink 61a16d2a16 Correctly combine alias.scope metadata by a union instead of intersecting Summary: The alias.scope metadata represents sets of things an instruction might alias with. When generically combining the metadata from two instructions the result must be the union of the original sets, because the new instruction might alias with anything any of the original instructions aliased with. Reviewers: hfinkel Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D7490 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228525 91177308-0d34-0410-b5e6-96231b3b80d8		2015-02-08 17:07:14 +00:00
..
IPA	[InstSimplify] Add SimplifyFPBinOp function.	2015-02-06 20:02:51 +00:00
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp
AssumptionCache.cpp
BasicAliasAnalysis.cpp	[BasicAA] Try to disambiguate GEPs through arrays of structs into	2015-02-07 17:04:29 +00:00
BlockFrequencyInfo.cpp
BlockFrequencyInfoImpl.cpp
BranchProbabilityInfo.cpp
CaptureTracking.cpp
CFG.cpp
CFGPrinter.cpp
CFLAliasAnalysis.cpp
CGSCCPassManager.cpp
CMakeLists.txt
CodeMetrics.cpp
ConstantFolding.cpp
CostModel.cpp
Delinearization.cpp
DependenceAnalysis.cpp
DominanceFrontier.cpp
DomPrinter.cpp
InstCount.cpp
InstructionSimplify.cpp	[InstSimplify] Add SimplifyFPBinOp function.	2015-02-06 20:02:51 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
JumpInstrTableInfo.cpp
LazyCallGraph.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp
LLVMBuild.txt
Loads.cpp
LoopAccessAnalysis.cpp	[LV] Move addRuntimeCheck to LoopAccessAnalysis	2015-02-06 18:31:04 +00:00
LoopInfo.cpp
LoopPass.cpp
Makefile
MemDepPrinter.cpp
MemDerefPrinter.cpp
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp	Whitespace.	2015-02-06 14:14:41 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PHITransAddr.cpp
PostDominators.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	SCEV: Compress disposition pairs.	2015-02-07 16:41:12 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
ScalarEvolutionNormalization.cpp
ScopedNoAliasAA.cpp
SparsePropagation.cpp
StratifiedSets.h
TargetLibraryInfo.cpp
TargetTransformInfo.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp	Correctly combine alias.scope metadata by a union instead of intersecting	2015-02-08 17:07:14 +00:00
ValueTracking.cpp	ValueTracking: Make isBytewiseValue simpler and more powerful at the same time.	2015-02-07 19:29:02 +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))

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