llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-11-04 22:07:27 +00:00

History

Richard Trieu f31ecd3927 Removing an "if (!this)" check from two print methods. The condition will never be true in a well-defined context. The checking for null pointers has been moved into the caller logic so it does not rely on undefined behavior. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210497 91177308-0d34-0410-b5e6-96231b3b80d8		2014-06-09 22:53:16 +00:00
..
IPA	Removing an "if (!this)" check from two print methods. The condition will	2014-06-09 22:53:16 +00:00
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp	Add a new attribute called 'jumptable' that creates jump-instruction tables for functions marked with this attribute.	2014-06-05 19:29:43 +00:00
BasicAliasAnalysis.cpp
BlockFrequencyInfo.cpp
BlockFrequencyInfoImpl.cpp
BranchProbabilityInfo.cpp
CaptureTracking.cpp
CFG.cpp
CFGPrinter.cpp	Clean up language and grammar.	2014-05-20 17:11:11 +00:00
CGSCCPassManager.cpp
CMakeLists.txt	Add a new attribute called 'jumptable' that creates jump-instruction tables for functions marked with this attribute.	2014-06-05 19:29:43 +00:00
CodeMetrics.cpp
ConstantFolding.cpp	Remove old fenv.h workaround for a historic clang driver bug	2014-06-09 19:00:52 +00:00
CostModel.cpp
Delinearization.cpp	remove BasePointer before delinearizing	2014-05-27 22:41:51 +00:00
DependenceAnalysis.cpp	remove BasePointer before delinearizing	2014-05-27 22:41:51 +00:00
DominanceFrontier.cpp
DomPrinter.cpp
InstCount.cpp
InstructionSimplify.cpp	InstSimplify: Improve handling of ashr/lshr	2014-05-16 17:14:03 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp	Removing an "if (!this)" check from two print methods. The condition will	2014-06-09 22:53:16 +00:00
JumpInstrTableInfo.cpp	Add a new attribute called 'jumptable' that creates jump-instruction tables for functions marked with this attribute.	2014-06-05 19:29:43 +00:00
LazyCallGraph.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp
LLVMBuild.txt
Loads.cpp
LoopInfo.cpp
LoopPass.cpp	Removing an "if (!this)" check from two print methods. The condition will	2014-06-09 22:53:16 +00:00
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PHITransAddr.cpp
PostDominators.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp	Removing an "if (!this)" check from two print methods. The condition will	2014-06-09 22:53:16 +00:00
RegionPrinter.cpp
ScalarEvolution.cpp	ScalarEvolution: Derive element size from the type of the loaded element	2014-06-08 19:21:20 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
ScalarEvolutionNormalization.cpp	test check-in: added missing parenthesis in comment	2014-05-28 19:03:33 +00:00
SparsePropagation.cpp
TargetTransformInfo.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	Teach isKnownNonNull that a nonnull return is not null. Add a test for this case as well as the case of a nonnull attribute (already handled but not tested).	2014-05-20 05:13:21 +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))

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