llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-11-02 07:11:49 +00:00

History

Ramkumar Ramachandra c904d5075f MemDerefPrinter: Require DataLayoutPass for higher accuracy Without a valid data layout, deferenceable(N) doesn't get parsed or propagated. Since this is the key item we are testing, add a dependency on the pass. Differential Revision: http://reviews.llvm.org/D7508 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228611 91177308-0d34-0410-b5e6-96231b3b80d8		2015-02-09 21:50:03 +00:00
..
IPA	[InstSimplify] Add SimplifyFPBinOp function.	2015-02-06 20:02:51 +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
CGSCCPassManager.cpp
CMakeLists.txt	Introduce print-memderefs to test isDereferenceablePointer	2015-02-06 01:46:42 +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	[InstSimplify] Add SimplifyFPBinOp function.	2015-02-06 20:02:51 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
JumpInstrTableInfo.cpp
LazyCallGraph.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp
LLVMBuild.txt
Loads.cpp
LoopAccessAnalysis.cpp	[LV] Move addRuntimeCheck to LoopAccessAnalysis	2015-02-06 18:31:04 +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	Whitespace.	2015-02-06 14:14:41 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PHITransAddr.cpp
PostDominators.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	Bugfix: SCEV incorrectly marks certain add recurrences as nsw	2015-02-09 18:34:55 +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))

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