llvm/lib/Analysis
Dan Gohman 837be07979 Revert the rule that considers comparisons between two pointers in the
same object to be a non-capture; Duncan pointed out a way that such
a comparison could be a capture.

Make the rule that considers a comparison against null more specific,
and only consider noalias return values compared against null. This
still supports test/Transforms/GVN/nonescaping-malloc.ll, and is not
susceptible to the problem Duncan pointed out with noalias arguments.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89468 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-20 17:50:21 +00:00
..
IPA Fix DenseMap iterator constness. 2009-11-10 01:02:17 +00:00
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp remove unneeded checks of isFreeCall 2009-11-03 05:35:19 +00:00
Analysis.cpp
BasicAliasAnalysis.cpp Extend CaptureTracking to indicate when a value is never stored, even 2009-11-19 21:57:48 +00:00
CaptureTracking.cpp Revert the rule that considers comparisons between two pointers in the 2009-11-20 17:50:21 +00:00
CFGPrinter.cpp
CMakeLists.txt Stub out a new lazy value info pass, which will eventually 2009-11-11 00:22:30 +00:00
ConstantFolding.cpp fix ConstantFoldCompareInstOperands to take the LHS/RHS as 2009-11-09 23:06:58 +00:00
DbgInfoPrinter.cpp
DebugInfo.cpp Remove dead code. 2009-11-17 22:39:08 +00:00
DomPrinter.cpp
InlineCost.cpp
InstCount.cpp
InstructionSimplify.cpp move some generally useful functions out of jump threading 2009-11-10 22:26:15 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp Teach IVUsers to keep things simpler and track loop-invariant strides only 2009-11-19 02:05:44 +00:00
LazyValueInfo.cpp typo spotted by duncan. 2009-11-16 03:51:42 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
LiveValues.cpp remove redundant foward declaration. This function is already in 2009-11-11 00:21:21 +00:00
LoopDependenceAnalysis.cpp
LoopInfo.cpp Teach getSmallConstantTripMultiple about Shl operators. 2009-11-20 01:09:34 +00:00
LoopPass.cpp
Makefile
MemoryBuiltins.cpp Simplify ComputeMultiple so that it doesn't depend on TargetData. 2009-11-18 00:58:27 +00:00
MemoryDependenceAnalysis.cpp
PointerTracking.cpp remove a bunch of extraneous LLVMContext arguments 2009-11-06 04:27:31 +00:00
PostDominators.cpp
ProfileEstimatorPass.cpp
ProfileInfo.cpp
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp
README.txt
ScalarEvolution.cpp Pass the (optional) TargetData object to ConstantFoldInstOperands 2009-11-09 23:34:17 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
SparsePropagation.cpp
Trace.cpp
ValueTracking.cpp Simplify ComputeMultiple so that it doesn't depend on TargetData. 2009-11-18 00:58:27 +00:00

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.

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