llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-17 18:31:04 +00:00

History

Benjamin Kramer 9f9dcf8046 Reduce double set lookups. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230798 91177308-0d34-0410-b5e6-96231b3b80d8		2015-02-27 21:43:14 +00:00
..
IPA
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp	Remove the Forward Control Flow Integrity pass and its dependencies.	2015-02-27 19:03:38 +00:00
AssumptionCache.cpp
BasicAliasAnalysis.cpp
BlockFrequencyInfo.cpp
BlockFrequencyInfoImpl.cpp
BranchProbabilityInfo.cpp
CaptureTracking.cpp
CFG.cpp
CFGPrinter.cpp
CFLAliasAnalysis.cpp
CGSCCPassManager.cpp
CMakeLists.txt	Remove the Forward Control Flow Integrity pass and its dependencies.	2015-02-27 19:03:38 +00:00
CodeMetrics.cpp
ConstantFolding.cpp
CostModel.cpp
Delinearization.cpp
DependenceAnalysis.cpp
DominanceFrontier.cpp
DomPrinter.cpp
InstCount.cpp
InstructionSimplify.cpp	InstSimplify: simplify 0 / X if nnan and nsz	2015-02-23 18:30:25 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LazyCallGraph.cpp
LazyValueInfo.cpp	Reduce double set lookups.	2015-02-27 21:43:14 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp
LLVMBuild.txt
Loads.cpp
LoopAccessAnalysis.cpp	[LV/LoopAccesses] Backward dependences are not safe just because the	2015-02-26 17:58:48 +00:00
LoopInfo.cpp
LoopPass.cpp
Makefile
MemDepPrinter.cpp	MemDepPrinter: Fix some nits introduced in r228596	2015-02-25 23:55:00 +00:00
MemDerefPrinter.cpp
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PHITransAddr.cpp
PostDominators.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	Fix bug 22641	2015-02-24 01:02:42 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	SCEVExpander incorrectly marks generated subtractions as nuw/nsw	2015-02-26 19:51:35 +00:00
ScalarEvolutionNormalization.cpp
ScopedNoAliasAA.cpp
SparsePropagation.cpp
StratifiedSets.h
TargetLibraryInfo.cpp
TargetTransformInfo.cpp	Prevent hoisting fmul from THEN/ELSE to IF if there is fmsub/fmadd opportunity.	2015-02-23 19:15:16 +00:00
Trace.cpp
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	Fix really obscure bug in CannotBeNegativeZero() (PR22688)	2015-02-25 18:00:15 +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))

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