llvm-6502

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

History

Arnold Schwaighofer 23463c9261 PR15967 Fix in basicaa for faulty returning no alias. This commit consist of two parts. The first part fix the PR15967. The wrong conclusion was made when the MaxLookup limit was reached. The fix introduce a out parameter (MaxLookupReached) to DecomposeGEPExpression that the function aliasGEP can act upon. The second part is introducing the constant MaxLookupSearchDepth to make sure that DecomposeGEPExpression and GetUnderlyingObject use the same search depth. This is a small cleanup to clarify the original algorithm. Patch by Karl-Johan Karlsson! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204859 91177308-0d34-0410-b5e6-96231b3b80d8		2014-03-26 21:30:19 +00:00
..
IPA	Consistent use of the noduplicate attribute.	2014-03-17 16:19:07 +00:00
AliasAnalysis.cpp	IR: add a second ordering operand to cmpxhg for failure	2014-03-11 10:48:52 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp	PR15967 Fix in basicaa for faulty returning no alias.	2014-03-26 21:30:19 +00:00
BlockFrequencyInfo.cpp	blockfreq: Implement Pass::releaseMemory()	2014-03-25 18:01:38 +00:00
BranchProbabilityInfo.cpp
CaptureTracking.cpp	[C++11] Add range based accessors for the Use-Def chain of a Value.	2014-03-09 03:16:01 +00:00
CFG.cpp	Simplify loop that worked around bugs in old GCC/Xcode.	2014-03-25 09:06:18 +00:00
CFGPrinter.cpp
CMakeLists.txt
CodeMetrics.cpp	Consistent use of the noduplicate attribute.	2014-03-17 16:19:07 +00:00
ConstantFolding.cpp	Allow constant folding of ceil function whenever feasible	2014-03-24 04:36:06 +00:00
CostModel.cpp
Delinearization.cpp
DependenceAnalysis.cpp
DominanceFrontier.cpp
DomPrinter.cpp
InstCount.cpp	[Layering] Move InstVisitor.h into the IR library as it is pretty	2014-03-06 03:23:41 +00:00
InstructionSimplify.cpp	[C++11] Add range based accessors for the Use-Def chain of a Value.	2014-03-09 03:16:01 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp	PR17473:	2014-03-12 21:31:05 +00:00
LazyCallGraph.cpp	[LCG] Ran clang-format over this too and it pointed out some fixes.	2014-03-10 02:14:14 +00:00
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp	Teach lint about address spaces	2014-03-06 17:33:55 +00:00
LLVMBuild.txt
Loads.cpp
LoopInfo.cpp	Consistent use of the noduplicate attribute.	2014-03-17 16:19:07 +00:00
LoopPass.cpp
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp	[C++11] Add range based accessors for the Use-Def chain of a Value.	2014-03-09 03:16:01 +00:00
MemoryDependenceAnalysis.cpp	Replace OwningPtr<T> with std::unique_ptr<T>.	2014-03-06 05:51:42 +00:00
ModuleDebugInfoPrinter.cpp	[C++11] Change DebugInfoFinder to use range-based loops	2014-03-18 09:41:07 +00:00
NoAliasAnalysis.cpp
PHITransAddr.cpp	[C++11] Add range based accessors for the Use-Def chain of a Value.	2014-03-09 03:16:01 +00:00
PostDominators.cpp
PtrUseVisitor.cpp	[C++11] Add range based accessors for the Use-Def chain of a Value.	2014-03-09 03:16:01 +00:00
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	ScalarEvolution: Compute exit counts for loops with a power-of-2 step.	2014-03-25 16:25:12 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	[C++11] Add range based accessors for the Use-Def chain of a Value.	2014-03-09 03:16:01 +00:00
ScalarEvolutionNormalization.cpp	Add stride normalization to SCEV Normalize/Denormalize transformation.	2014-03-18 17:34:03 +00:00
SparsePropagation.cpp	[C++11] Add range based accessors for the Use-Def chain of a Value.	2014-03-09 03:16:01 +00:00
TargetTransformInfo.cpp	[Constant Hoisting] Make the constant materialization cost operand dependent	2014-03-21 06:04:45 +00:00
Trace.cpp
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	[C++11] Add range based accessors for the Use-Def chain of a Value.	2014-03-09 03:16:01 +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))

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