llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-09-30 19:55:11 +00:00

History

Adam Nemet 718b023033 [LoopAccesses] Create the analysis pass This is a function pass that runs the analysis on demand. The analysis can be initiated by querying the loop access info via LAA::getInfo. It either returns the cached info or runs the analysis. Symbolic stride information continues to reside outside of this analysis pass. We may move it inside later but it's not a priority for me right now. The idea is that Loop Distribution won't support run-time stride checking at least initially. This means that when querying the analysis, symbolic stride information can be provided optionally. Whether stride information is used can invalidate the cache entry and rerun the analysis. Note that if the loop does not have any symbolic stride, the entry should be preserved across Loop Distribution and LV. Since currently the only user of the pass is LV, I just check that the symbolic stride information didn't change when using a cached result. On the LV side, LoopVectorizationLegality requests the info object corresponding to the loop from the analysis pass. A large chunk of the diff is due to LAI becoming a pointer from a reference. A test will be added as part of the -analyze patch. Also tested that with AVX, we generate identical assembly output for the testsuite (including the external testsuite) before and after. This is part of the patchset that converts LoopAccessAnalysis into an actual analysis pass. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229626 91177308-0d34-0410-b5e6-96231b3b80d8		2015-02-18 03:43:24 +00:00
..
IPA	Analysis: Canonicalize access to function attributes, NFC	2015-02-14 00:12:15 +00:00
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp	Introduce print-memderefs to test isDereferenceablePointer	2015-02-06 01:46:42 +00:00
AssumptionCache.cpp
BasicAliasAnalysis.cpp	[BasicAA] Try to disambiguate GEPs through arrays of structs into	2015-02-07 17:04:29 +00:00
BlockFrequencyInfo.cpp
BlockFrequencyInfoImpl.cpp
BranchProbabilityInfo.cpp
CaptureTracking.cpp
CFG.cpp
CFGPrinter.cpp
CFLAliasAnalysis.cpp	Fixed a bug where CFLAA would crash the compiler.	2015-02-12 03:07:07 +00:00
CGSCCPassManager.cpp
CMakeLists.txt	Use ADDITIONAL_HEADER_DIRS in all LLVM CMake projects.	2015-02-11 03:28:02 +00:00
CodeMetrics.cpp
ConstantFolding.cpp
CostModel.cpp	[multiversion] Thread a function argument through all the callers of the	2015-02-01 12:01:35 +00:00
Delinearization.cpp
DependenceAnalysis.cpp
DominanceFrontier.cpp
DomPrinter.cpp
InstCount.cpp
InstructionSimplify.cpp	InstCombine: cleanup redundant dyn_cast<> (NFC)	2015-02-13 07:38:04 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
JumpInstrTableInfo.cpp
LazyCallGraph.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp	Unify the two EH personality classification routines I wrote	2015-02-14 00:21:02 +00:00
Lint.cpp	[PM] Remove the old 'PassManager.h' header file at the top level of	2015-02-13 10:01:29 +00:00
LLVMBuild.txt
Loads.cpp
LoopAccessAnalysis.cpp	[LoopAccesses] Create the analysis pass	2015-02-18 03:43:24 +00:00
LoopInfo.cpp
LoopPass.cpp
Makefile
MemDepPrinter.cpp	MemDepPrinter: cleanup a few loops (NFC)	2015-02-09 19:49:54 +00:00
MemDerefPrinter.cpp	MemDerefPrinter: Require DataLayoutPass for higher accuracy	2015-02-09 21:50:03 +00:00
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp	Revert 229175	2015-02-15 19:07:31 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PHITransAddr.cpp
PostDominators.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	Generalize getExtendAddRecStart to work with both sign and zero	2015-02-18 01:47:07 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
ScalarEvolutionNormalization.cpp
ScopedNoAliasAA.cpp
SparsePropagation.cpp
StratifiedSets.h
TargetLibraryInfo.cpp
TargetTransformInfo.cpp	Value soft float calls as more expensive in the inliner.	2015-02-05 02:09:33 +00:00
Trace.cpp
TypeBasedAliasAnalysis.cpp	Correctly combine alias.scope metadata by a union instead of intersecting	2015-02-08 17:07:14 +00:00
ValueTracking.cpp	ValueTracking: Make isBytewiseValue simpler and more powerful at the same time.	2015-02-07 19:29:02 +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))

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