llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-15 04:30:12 +00:00

History

Hal Finkel 7e32aa1015 Simplify pointer comparisons involving memory allocation functions System memory allocation functions, which are identified at the IR level by the noalias attribute on the return value, must return a pointer into a memory region disjoint from any other memory accessible to the caller. We can use this property to simplify pointer comparisons between allocated memory and local stack addresses and the addresses of global variables. Neither the stack nor global variables can overlap with the region used by the memory allocator. Fixes PR21556. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223093 91177308-0d34-0410-b5e6-96231b3b80d8		2014-12-01 23:38:06 +00:00
..
IPA	Remove the unused FindUsedTypes pass.	2014-11-24 20:53:26 +00:00
AliasAnalysis.cpp	Reformat partially, where I touched for whitespace changes.	2014-10-28 11:54:52 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp	AliasSet: Simplify mergeSetIn	2014-11-19 19:36:18 +00:00
Analysis.cpp	Revert "Don't make assumptions about the name of private global variables."	2014-11-15 02:03:53 +00:00
AssumptionTracker.cpp	Clean up assume intrinsic pattern matching, no need to check that the argument is a value.	2014-10-25 18:09:01 +00:00
BasicAliasAnalysis.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
BlockFrequencyInfo.cpp
BlockFrequencyInfoImpl.cpp
BranchProbabilityInfo.cpp	Revert "IR: MDNode => Value"	2014-11-11 21:30:22 +00:00
CaptureTracking.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
CFG.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
CFGPrinter.cpp
CFLAliasAnalysis.cpp	Remove redundant virtual on overriden functions.	2014-11-14 19:06:36 +00:00
CGSCCPassManager.cpp
CMakeLists.txt
CodeMetrics.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
ConstantFolding.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
CostModel.cpp
Delinearization.cpp
DependenceAnalysis.cpp	[DependenceAnalysis] Allow subscripts of different types	2014-11-16 16:52:44 +00:00
DominanceFrontier.cpp
DomPrinter.cpp
FunctionTargetTransformInfo.cpp
InstCount.cpp
InstructionSimplify.cpp	Simplify pointer comparisons involving memory allocation functions	2014-12-01 23:38:06 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
JumpInstrTableInfo.cpp	Add Forward Control-Flow Integrity.	2014-11-11 21:08:02 +00:00
LazyCallGraph.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
LazyValueInfo.cpp	LazyValueInfo: Actually re-visit partially solved block-values in solveBlockValue()	2014-11-25 17:23:05 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp	remove function names from comments; NFC	2014-10-21 18:26:57 +00:00
Lint.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
LLVMBuild.txt
Loads.cpp	Revert r220349 to re-instate r220277 with a fix for PR21330 -- quite	2014-11-25 08:20:27 +00:00
LoopInfo.cpp	Revert "IR: MDNode => Value"	2014-11-11 21:30:22 +00:00
LoopPass.cpp
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
MemoryDependenceAnalysis.cpp	Relax an assert a bit to avoid a crash on unreachable code.	2014-12-01 02:55:24 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PHITransAddr.cpp
PostDominators.cpp
PtrUseVisitor.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
ScalarEvolutionNormalization.cpp
ScopedNoAliasAA.cpp	Revert "IR: MDNode => Value"	2014-11-11 21:30:22 +00:00
SparsePropagation.cpp
StratifiedSets.h	Update SetVector to rely on the underlying set's insert to return a pair<iterator, bool>	2014-11-19 07:49:26 +00:00
TargetTransformInfo.cpp	[Statepoints 1/4] Statepoint infrastructure for garbage collection: IR Intrinsics	2014-12-01 21:18:12 +00:00
Trace.cpp
TypeBasedAliasAnalysis.cpp	Revert "IR: MDNode => Value"	2014-11-11 21:30:22 +00:00
ValueTracking.cpp	Factor check for the assume intrinsic out of checks in computeKnownBitsFromAssume	2014-11-24 23:44:28 +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))

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