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History

Hal Finkel 198ffea54f Revert: r189565 - Add getUnrollingPreferences to TTI Revert unintentional commit (of an unreviewed change). Original commit message: Add getUnrollingPreferences to TTI Allow targets to customize the default behavior of the generic loop unrolling transformation. This will be used by the PowerPC backend when targeting the A2 core (which is in-order with a deep pipeline), and using more aggressive defaults is important. llvm-svn: 189566		2013-08-29 03:33:15 +00:00
..
IPA	Disable inlining between sanitized and non-sanitized functions.	2013-08-08 08:22:39 +00:00
AliasAnalysis.cpp	Reimplement isPotentiallyReachable to make nocapture deduction much stronger.	2013-07-27 01:24:00 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp	Support in AAEvaluator to print alias queries of loads/stores with TBAA tags.	2013-03-22 22:34:41 +00:00
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp	This patch breaks up Wrap.h so that it does not have to include all of	2013-05-01 20:59:00 +00:00
BasicAliasAnalysis.cpp	Remove trailing spaces.	2013-08-24 14:16:00 +00:00
BlockFrequencyInfo.cpp	BlockFrequency: Bump up the entry frequency a bit.	2013-06-25 13:34:40 +00:00
BranchProbabilityInfo.cpp	Use SmallVectorImpl::iterator/const_iterator instead of SmallVector to avoid specifying the vector size.	2013-07-04 01:31:24 +00:00
CaptureTracking.cpp	Extend 'readonly' and 'readnone' to work on function arguments as well as	2013-07-06 00:29:58 +00:00
CFG.cpp	Add some constantness.	2013-08-20 23:04:15 +00:00
CFGPrinter.cpp
CMakeLists.txt	Also update CMakeLists.txt for r187283.	2013-07-27 01:25:51 +00:00
CodeMetrics.cpp	Begin fleshing out an interface in TTI for modelling the costs of	2013-01-22 11:26:02 +00:00
ConstantFolding.cpp	Teach ConstantFolding about pointer address spaces	2013-08-20 21:20:04 +00:00
CostModel.cpp	Use SmallVectorImpl& instead of SmallVector to avoid repeating small vector size.	2013-07-11 16:22:38 +00:00
DependenceAnalysis.cpp	Remove extraneous semicolon.	2013-08-06 16:40:40 +00:00
DominanceFrontier.cpp
DomPrinter.cpp
InstCount.cpp
InstructionSimplify.cpp	Add ISD::FROUND for libm round()	2013-08-07 22:49:12 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LazyValueInfo.cpp	Use SmallVectorImpl::iterator/const_iterator instead of SmallVector to avoid specifying the vector size.	2013-07-04 01:31:24 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp	Fix lint assert on integer vector division	2013-08-26 23:29:33 +00:00
LLVMBuild.txt
Loads.cpp	Change GetPointerBaseWithConstantOffset's DataLayout argument from a	2013-01-31 02:00:45 +00:00
LoopInfo.cpp	Add 'const' qualifiers to static const char* variables.	2013-07-16 01:17:10 +00:00
LoopPass.cpp	Comment: try to clarify loop iteration order.	2013-07-20 23:10:31 +00:00
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp	Treat nothrow forms of ::operator delete and ::operator delete[] as	2013-07-21 23:11:42 +00:00
MemoryDependenceAnalysis.cpp	Fix xemacs mode line, don't put them in .cpp files (just header files). No	2013-06-10 23:10:59 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PathNumbering.cpp
PathProfileInfo.cpp
PathProfileVerifier.cpp	Build fixes for STLPort + GCC	2013-03-29 18:48:45 +00:00
PHITransAddr.cpp
PostDominators.cpp
ProfileDataLoader.cpp	Use SmallVectorImpl& instead of SmallVector to avoid repeating small vector size.	2013-07-14 04:42:23 +00:00
ProfileDataLoaderPass.cpp	Revert "Add LLVMContext::emitWarning methods and use them. <rdar://problem/12867368>"	2013-02-08 21:48:29 +00:00
ProfileEstimatorPass.cpp	Use SmallVectorImpl::iterator/const_iterator instead of SmallVector to avoid specifying the vector size.	2013-07-04 01:31:24 +00:00
ProfileInfo.cpp	Build fixes for STLPort + GCC	2013-03-29 18:48:45 +00:00
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp	Revert "Add LLVMContext::emitWarning methods and use them. <rdar://problem/12867368>"	2013-02-08 21:48:29 +00:00
ProfileVerifierPass.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp	Reorder headers according to lint.	2013-08-21 21:14:19 +00:00
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	Fix a severe compile time problem when forming large SCEV expressions.	2013-07-31 02:43:40 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	Fix SCEVExpander creating distinct duplicate PHI entries	2013-08-18 00:16:23 +00:00
ScalarEvolutionNormalization.cpp
SparsePropagation.cpp
TargetTransformInfo.cpp	Revert: r189565 - Add getUnrollingPreferences to TTI	2013-08-29 03:33:15 +00:00
Trace.cpp
TypeBasedAliasAnalysis.cpp	Struct-path aware TBAA: change the format of TBAAStructType node.	2013-04-27 00:26:11 +00:00
ValueTracking.cpp	Fix assert with GEP ptr vector indexing structs	2013-08-19 21:43:16 +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))

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