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History

Michael Gottesman 37877d5d63 Added BlockFrequencyInfo::view for displaying the block frequency propagation graph via graphviz. This is useful for debugging issues in the BlockFrequency implementation since one can easily visualize where probability mass and other errors occur in the propagation. llvm-svn: 194654		2013-11-14 02:27:46 +00:00
..
IPA	Move the old pass manager infrastructure into a legacy namespace and	2013-11-09 12:26:54 +00:00
AliasAnalysis.cpp	Reimplement isPotentiallyReachable to make nocapture deduction much stronger.	2013-07-27 01:24:00 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp	In AliasSetTracker, do not change the alias set to "mod/ref" when adding	2013-09-12 20:15:50 +00:00
Analysis.cpp	delinearization of arrays	2013-11-12 22:47:20 +00:00
BasicAliasAnalysis.cpp	Revert r193251 : Use address-taken to disambiguate global variable and indirect memops.	2013-10-27 03:08:44 +00:00
BlockFrequencyInfo.cpp	Added BlockFrequencyInfo::view for displaying the block frequency propagation graph via graphviz.	2013-11-14 02:27:46 +00:00
BranchProbabilityInfo.cpp	Consider (x == -1) unlikely in BranchProbabilityInfo	2013-11-01 10:58:22 +00:00
CaptureTracking.cpp	CaptureTracking: Plug a loophole in the "too many uses" heuristic.	2013-10-03 13:24:02 +00:00
CFG.cpp	Add some constantness.	2013-08-20 23:04:15 +00:00
CFGPrinter.cpp
CMakeLists.txt	delinearization of arrays	2013-11-12 22:47:20 +00:00
CodeMetrics.cpp
ConstantFolding.cpp	Fix another constant folding address space place I missed.	2013-11-04 20:46:52 +00:00
CostModel.cpp	Move variable into assert to avoid unused variable warning.	2013-09-17 21:13:57 +00:00
Delinearization.cpp	add more comments around the delinearization of arrays	2013-11-13 22:37:58 +00:00
DependenceAnalysis.cpp	add more comments around the delinearization of arrays	2013-11-13 22:37:58 +00:00
DominanceFrontier.cpp
DomPrinter.cpp
InstCount.cpp
InstructionSimplify.cpp	Teach MemoryBuiltins and InstructionSimplify that operator new never returns NULL.	2013-09-24 16:37:51 +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	Use size function instead of manually calculating it.	2013-11-10 03:18:50 +00:00
LLVMBuild.txt
Loads.cpp
LoopInfo.cpp	Simplify code. No functionality change.	2013-11-13 20:18:38 +00:00
LoopPass.cpp	Comment: try to clarify loop iteration order.	2013-07-20 23:10:31 +00:00
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp	fix PR17635: false positive with packed structures	2013-10-24 09:17:24 +00:00
MemoryDependenceAnalysis.cpp	Fixing a heisenbug where the memory dependence analysis behaves differently	2013-11-14 01:10:52 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PHITransAddr.cpp
PostDominators.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	add more comments around the delinearization of arrays	2013-11-13 22:37:58 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	Fix SCEVExpander: don't try to expand quadratic recurrences outside a loop.	2013-10-25 21:35:56 +00:00
ScalarEvolutionNormalization.cpp	Fix LSR: don't normalize quadratic recurrences.	2013-10-25 21:35:52 +00:00
SparsePropagation.cpp
TargetTransformInfo.cpp	Costmodel: Add support for horizontal vector reductions	2013-09-17 18:06:50 +00:00
Trace.cpp
TypeBasedAliasAnalysis.cpp	TBAA: fix PR17620.	2013-10-22 01:40:25 +00:00
ValueTracking.cpp	Remove x86_sse42_crc32_64_8 intrinsic. It has no functional difference from x86_sse42_crc32_32_8 and was not mapped to a clang builtin. I'm not even sure why this form of the instruction is even called out explicitly in the docs. Also add AutoUpgrade support to convert it into the other intrinsic with appropriate trunc and zext.	2013-10-15 05:20:47 +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))

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