llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-10-17 03:26:03 +00:00

History

Andrew Trick d152d03a47 Fix SCEVEXpander to handle arbitrary phi expansion. Includes two related bug fixes and corresponding assertions for uninitialized data and missing NULL check. Test cases will be included with the new LFTR. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135333 91177308-0d34-0410-b5e6-96231b3b80d8		2011-07-16 00:59:39 +00:00
..
IPA
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp
BlockFrequency.cpp
BranchProbabilityInfo.cpp	Fix pointer heuristic. Check whether predicator is ICMP_NE instead of if it is	2011-07-15 20:51:06 +00:00
CaptureTracking.cpp
CFGPrinter.cpp
CMakeLists.txt
ConstantFolding.cpp	Convert InsertValueInst and ExtractValueInst APIs to use ArrayRef.	2011-07-13 10:26:04 +00:00
DbgInfoPrinter.cpp
DebugInfo.cpp
DIBuilder.cpp	Convert CallInst and InvokeInst APIs to use ArrayRef.	2011-07-15 08:37:34 +00:00
DominanceFrontier.cpp
DomPrinter.cpp
InlineCost.cpp
InstCount.cpp
InstructionSimplify.cpp
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp	Convert InsertValueInst and ExtractValueInst APIs to use ArrayRef.	2011-07-13 10:26:04 +00:00
Loads.cpp
LoopDependenceAnalysis.cpp
LoopInfo.cpp
LoopPass.cpp
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PathNumbering.cpp
PathProfileInfo.cpp
PathProfileVerifier.cpp
PHITransAddr.cpp
PostDominators.cpp
ProfileEstimatorPass.cpp
ProfileInfo.cpp
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	Fix SCEVEXpander to handle arbitrary phi expansion. Includes two	2011-07-16 00:59:39 +00:00
ScalarEvolutionNormalization.cpp
SparsePropagation.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	Convert InsertValueInst and ExtractValueInst APIs to use ArrayRef.	2011-07-13 10:26:04 +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))

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