llvm-6502/lib/Analysis
Wan Xiaofei 3cda2d3885 Change data structure to memorize computed result in ScalarEvolution
Replace std::map with SmallVector to memorize the cached result since SCEV usually belongs to little Loop/BB
Linear scan on SmallVector is faster than std::map.

Code reviewer : Andrew Trick.
Test result   : Pass Unit Test & LLVM Test Suite

401.bzip2	0.425721	0.419981	101.37%
403.gcc		24.53855	24.2667		101.12%
429.mcf		0.060847	0.059944	101.51%
433.milc	0.646009	0.636119	101.55%
444.namd	1.383928	1.370614	100.97%
445.gobmk	5.836575	5.800225	100.63%
450.soplex	1.911257	1.895963	100.81%
456.hmmer	1.039565	1.032534	100.68%
458.sjeng	0.897401	0.885567	101.34%
464.h264ref	3.645908	3.577991	101.90%
470.lbm		0.049456	0.048398	102.19%
471.omnetpp	5.638575	5.60435		100.61%
bitmnp01	0.045738	0.045291	100.99%
cjpegv2data	0.304359	0.302833	100.50%
idctrn01	0.046433	0.045763	101.46%
quake2		4.534416	4.4952		100.87%
quake		2.688566	2.659208	101.10%
xcsoar		12.42545	12.30385	100.99%
linpack		0.038739	0.03803		101.86%
matrix01	0.053564	0.0528		101.45%
nbench		0.402867	0.395803	101.78%
tblook01	0.021265	0.021015	101.19%
ttsprk01	0.066384	0.065566	101.25%

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194459 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-12 09:40:41 +00:00
..
IPA Move the old pass manager infrastructure into a legacy namespace and 2013-11-09 12:26:54 +00:00
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp Revert r193251 : Use address-taken to disambiguate global variable and indirect memops. 2013-10-27 03:08:44 +00:00
BlockFrequencyInfo.cpp
BranchProbabilityInfo.cpp Consider (x == -1) unlikely in BranchProbabilityInfo 2013-11-01 10:58:22 +00:00
CaptureTracking.cpp
CFG.cpp
CFGPrinter.cpp
CMakeLists.txt
CodeMetrics.cpp
ConstantFolding.cpp Fix another constant folding address space place I missed. 2013-11-04 20:46:52 +00:00
CostModel.cpp
DependenceAnalysis.cpp
DominanceFrontier.cpp
DomPrinter.cpp
InstCount.cpp
InstructionSimplify.cpp
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp Use size function instead of manually calculating it. 2013-11-10 03:18:50 +00:00
LLVMBuild.txt
Loads.cpp
LoopInfo.cpp Quick look-up for block in loop. 2013-10-26 03:08:02 +00:00
LoopPass.cpp
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp fix PR17635: false positive with packed structures 2013-10-24 09:17:24 +00:00
MemoryDependenceAnalysis.cpp
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PHITransAddr.cpp
PostDominators.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp Change data structure to memorize computed result in ScalarEvolution 2013-11-12 09:40:41 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp Fix SCEVExpander: don't try to expand quadratic recurrences outside a loop. 2013-10-25 21:35:56 +00:00
ScalarEvolutionNormalization.cpp Fix LSR: don't normalize quadratic recurrences. 2013-10-25 21:35:52 +00:00
SparsePropagation.cpp
TargetTransformInfo.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp TBAA: fix PR17620. 2013-10-22 01:40:25 +00:00
ValueTracking.cpp

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))

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