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llvm-mirror/lib/Analysis
David Majnemer f2223dee20 ScalarEvolution: Introduce SCEVSDivision and SCEVUDivision
It turns out that not all users of SCEVDivision want the same
signedness.  Let the users determine which operation they'd like by
explicitly choosing SCEVUDivision or SCEVSDivision.

findArrayDimensions and computeAccessFunctions will use SCEVSDivision
while HowFarToZero will use SCEVUDivision.

llvm-svn: 222104
2014-11-16 20:35:19 +00:00
..
IPA CGSCC should not treat intrinsic calls like function calls (PR21403) 2014-11-12 18:25:47 +00:00
AliasAnalysis.cpp Reformat partially, where I touched for whitespace changes. 2014-10-28 11:54:52 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp Use AA in LoadCombine 2014-11-03 23:19:16 +00:00
Analysis.cpp Revert "Don't make assumptions about the name of private global variables." 2014-11-15 02:03:53 +00:00
AssumptionTracker.cpp Clean up assume intrinsic pattern matching, no need to check that the argument is a value. 2014-10-25 18:09:01 +00:00
BasicAliasAnalysis.cpp Revert r219432 - "Revert "[BasicAA] Revert "Revert r218714 - Make better use of zext and sign information.""" 2014-11-13 09:16:54 +00:00
BlockFrequencyInfo.cpp
BlockFrequencyInfoImpl.cpp [modules] Stop excluding Support/Debug.h from the Support module. This header 2014-10-13 00:41:03 +00:00
BranchProbabilityInfo.cpp Revert "IR: MDNode => Value" 2014-11-11 21:30:22 +00:00
CaptureTracking.cpp
CFG.cpp
CFGPrinter.cpp Modernize raw_fd_ostream's constructor a bit. 2014-08-25 18:16:47 +00:00
CFLAliasAnalysis.cpp Remove redundant virtual on overriden functions. 2014-11-14 19:06:36 +00:00
CGSCCPassManager.cpp
CMakeLists.txt Add file to CMake build as well. 2014-09-18 00:39:20 +00:00
CodeMetrics.cpp Treat the WorkSet used to find ephemeral values as double-ended 2014-10-15 17:34:48 +00:00
ConstantFolding.cpp [InstSimplify] Support constant folding to vector of pointers 2014-10-22 12:18:48 +00:00
CostModel.cpp
Delinearization.cpp
DependenceAnalysis.cpp [DependenceAnalysis] Allow subscripts of different types 2014-11-16 16:52:44 +00:00
DominanceFrontier.cpp
DomPrinter.cpp
FunctionTargetTransformInfo.cpp Add a new pass FunctionTargetTransformInfo. This pass serves as a 2014-09-18 00:34:14 +00:00
InstCount.cpp
InstructionSimplify.cpp InstSimplify: Optimize ICmpInst xform that uses computeKnownBits 2014-11-16 02:20:08 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
JumpInstrTableInfo.cpp Add Forward Control-Flow Integrity. 2014-11-11 21:08:02 +00:00
LazyCallGraph.cpp
LazyValueInfo.cpp [LVI] Add some additional comments about caching and context instructions 2014-10-16 00:40:05 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp remove function names from comments; NFC 2014-10-21 18:26:57 +00:00
Lint.cpp Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.) 2014-09-07 18:57:58 +00:00
LLVMBuild.txt
Loads.cpp Revert "Teach the load analysis to allow finding available values which require" (r220277) 2014-10-21 23:49:52 +00:00
LoopInfo.cpp Revert "IR: MDNode => Value" 2014-11-11 21:30:22 +00:00
LoopPass.cpp Fix assertion in LICM doFinalization() 2014-09-24 16:48:31 +00:00
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp PR21145: Teach LLVM about C++14 sized deallocation functions. 2014-10-03 20:17:06 +00:00
MemoryDependenceAnalysis.cpp Silence a -Wsign-compare warning. NFC. 2014-10-02 13:17:11 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp Simplify code. No functionality change. 2014-10-05 12:21:57 +00:00
PHITransAddr.cpp Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.) 2014-09-07 18:57:58 +00:00
PostDominators.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp ScalarEvolution: Introduce SCEVSDivision and SCEVUDivision 2014-11-16 20:35:19 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.) 2014-09-07 18:57:58 +00:00
ScalarEvolutionNormalization.cpp Fix typos in comments, NFC 2014-08-29 21:53:01 +00:00
ScopedNoAliasAA.cpp Revert "IR: MDNode => Value" 2014-11-11 21:30:22 +00:00
SparsePropagation.cpp
StratifiedSets.h [CFLAA] And even more MSVC fixes 2014-09-02 23:50:01 +00:00
TargetTransformInfo.cpp Add minnum / maxnum intrinsics 2014-10-21 23:00:20 +00:00
Trace.cpp
TypeBasedAliasAnalysis.cpp Revert "IR: MDNode => Value" 2014-11-11 21:30:22 +00:00
ValueTracking.cpp Revert "IR: MDNode => Value" 2014-11-11 21:30:22 +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.

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

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))

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