llvm-6502/lib/Analysis
David Majnemer cb9d4667b7 isKnownToBeAPowerOfTwo: (X & Y) + Y is a power of 2 or zero if y is also.
This is useful if something that looks like (x & (1 << y)) ? 64 : 32 is
the divisor in a modulo operation.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182200 91177308-0d34-0410-b5e6-96231b3b80d8
2013-05-18 19:30:37 +00:00
..
IPA This patch breaks up Wrap.h so that it does not have to include all of 2013-05-01 20:59:00 +00:00
AliasAnalysis.cpp Move isKnownNonNull out of AliasAnalysis.h and into ValueTracking.cpp since 2013-01-31 02:40:59 +00:00
AliasAnalysisCounter.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
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 Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
AliasSetTracker.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
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 Revert r176408 and r176407 to address PR15540. 2013-04-09 18:16:05 +00:00
BlockFrequencyInfo.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
BranchProbabilityInfo.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
CaptureTracking.cpp Remove unneeded #includes. Use forward declarations instead. 2013-03-10 00:34:01 +00:00
CFGPrinter.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
CMakeLists.txt Remove -print-dbginfo as it is unused & bitrotten. 2013-03-08 18:17:46 +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 ConstantFolding: ComputeMaskedBits wants the scalar size for vectors. 2013-04-19 16:56:24 +00:00
CostModel.cpp CostModel: Add parameter to instruction cost to further classify operand values 2013-04-04 23:26:21 +00:00
DependenceAnalysis.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
DominanceFrontier.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
DomPrinter.cpp remove the blank line from previous ci. 2012-02-04 03:18:47 +00:00
InstCount.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
InstructionSimplify.cpp InstructionSimplify.cpp: Fix a ligature, "fi", to get rid of utf8 in comment. 2013-04-08 23:05:21 +00:00
Interval.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
IntervalPartition.cpp Now with fewer extraneous semicolons! 2010-10-07 22:25:06 +00:00
IVUsers.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
LazyValueInfo.cpp Move isKnownNonNull out of AliasAnalysis.h and into ValueTracking.cpp since 2013-01-31 02:40:59 +00:00
LibCallAliasAnalysis.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
LibCallSemantics.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
Lint.cpp Change GetPointerBaseWithConstantOffset's DataLayout argument from a 2013-01-31 02:00:45 +00:00
LLVMBuild.txt LLVMBuild: Introduce a common section which currently has a list of the 2011-12-12 22:45:54 +00:00
Loads.cpp Change GetPointerBaseWithConstantOffset's DataLayout argument from a 2013-01-31 02:00:45 +00:00
LoopInfo.cpp Metadata for annotating loops as parallel. The first consumer for this 2013-02-13 18:08:57 +00:00
LoopPass.cpp Enable the new LoopInfo algorithm by default. 2012-06-26 04:11:38 +00:00
Makefile
MemDepPrinter.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
MemoryBuiltins.cpp Respect the 'nobuiltin' attribute when determining if a call is to a memory builtin. 2013-05-16 04:12:04 +00:00
MemoryDependenceAnalysis.cpp Use only explicit bool conversion operators 2013-05-15 07:36:59 +00:00
ModuleDebugInfoPrinter.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
NoAliasAnalysis.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
PathNumbering.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
PathProfileInfo.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
PathProfileVerifier.cpp Build fixes for STLPort + GCC 2013-03-29 18:48:45 +00:00
PHITransAddr.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
PostDominators.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
ProfileDataLoader.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +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 the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
ProfileInfo.cpp Build fixes for STLPort + GCC 2013-03-29 18:48:45 +00:00
ProfileInfoLoader.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
ProfileInfoLoaderPass.cpp Revert "Add LLVMContext::emitWarning methods and use them. <rdar://problem/12867368>" 2013-02-08 21:48:29 +00:00
ProfileVerifierPass.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
PtrUseVisitor.cpp Hoist the GEP constant address offset computation to a common home on 2012-12-11 10:29:10 +00:00
README.txt
RegionInfo.cpp RegionInfo: Do not crash if unreachable block is found 2013-05-03 15:48:34 +00:00
RegionPass.cpp Remove the the block_node_iterator of Region, replace it by the block_iterator. 2012-08-27 13:49:24 +00:00
RegionPrinter.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
ScalarEvolution.cpp Fix SCEV forgetMemoizedResults should search and destroy backedge exprs. 2013-03-26 03:14:53 +00:00
ScalarEvolutionAliasAnalysis.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
ScalarEvolutionExpander.cpp SCEVExpander fix. RAUW needs to update the InsertedExpressions cache. 2013-01-14 21:00:37 +00:00
ScalarEvolutionNormalization.cpp More dead code removal (using -Wunreachable-code) 2012-01-20 21:51:11 +00:00
SparsePropagation.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
TargetTransformInfo.cpp CostModel: Add parameter to instruction cost to further classify operand values 2013-04-04 23:26:21 +00:00
Trace.cpp Move all of the header files which are involved in modelling the LLVM IR 2013-01-02 11:36:10 +00:00
TypeBasedAliasAnalysis.cpp Struct-path aware TBAA: change the format of TBAAStructType node. 2013-04-27 00:26:11 +00:00
ValueTracking.cpp isKnownToBeAPowerOfTwo: (X & Y) + Y is a power of 2 or zero if y is also. 2013-05-18 19:30:37 +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))

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