llvm/lib/Analysis
Nick Lewycky 6e9e010752 Teach basicaa about memcpy/memmove/memset. The length argument can be used to
improve alias results if constant, and the source pointer can't be modified.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84175 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-15 07:11:24 +00:00
..
IPA
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp Teach basicaa about memcpy/memmove/memset. The length argument can be used to 2009-10-15 07:11:24 +00:00
CaptureTracking.cpp
CFGPrinter.cpp
CMakeLists.txt Update the other CMake file. 2009-10-13 18:50:54 +00:00
ConstantFolding.cpp
DbgInfoPrinter.cpp
DebugInfo.cpp
InlineCost.cpp Compute a full cost value even when a setjmp call is found. 2009-10-13 20:10:10 +00:00
InstCount.cpp
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
LiveValues.cpp
LoopDependenceAnalysis.cpp
LoopInfo.cpp
LoopPass.cpp
Makefile
MallocHelper.cpp
MemoryDependenceAnalysis.cpp
PointerTracking.cpp
PostDominators.cpp
ProfileEstimatorPass.cpp
ProfileInfo.cpp
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp
README.txt
ScalarEvolution.cpp
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
SparsePropagation.cpp
Trace.cpp
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.

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