llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-11-02 22:04:55 +00:00

History

David Majnemer fe0d65bcc6 [InstSimplify] Handle some overflow intrinsics in InstSimplify This change does a few things: - Move some InstCombine transforms to InstSimplify - Run SimplifyCall from within InstCombine::visitCallInst - Teach InstSimplify to fold [us]mul_with_overflow(X, undef) to 0. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237995 91177308-0d34-0410-b5e6-96231b3b80d8		2015-05-22 03:56:46 +00:00
..
IPA
AliasAnalysis.cpp	Test commit: Remove unnecessary spaces.	2015-05-13 15:04:14 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp	Constify arguments in AliasSetTracker methods. NFC	2015-05-13 01:12:12 +00:00
Analysis.cpp
AssumptionCache.cpp
BasicAliasAnalysis.cpp	Revert r236894 "[BasicAA] Fix zext & sext handling"	2015-05-22 01:27:37 +00:00
BlockFrequencyInfo.cpp
BlockFrequencyInfoImpl.cpp
BranchProbabilityInfo.cpp	Fix information loss in branch probability computation.	2015-05-07 17:22:06 +00:00
CaptureTracking.cpp
CFG.cpp
CFGPrinter.cpp
CFLAliasAnalysis.cpp	Convert PHI getIncomingValue() to foreach over incoming_values(). NFC.	2015-05-12 20:05:31 +00:00
CGSCCPassManager.cpp
CMakeLists.txt
CodeMetrics.cpp
ConstantFolding.cpp	[ConstantFolding] Fix wrong folding of intrinsic 'convert.from.fp16'.	2015-05-14 18:01:48 +00:00
CostModel.cpp
Delinearization.cpp
DependenceAnalysis.cpp	[DependenceAnalysis] Fix for PR21585: collectUpperBound triggers asserts	2015-05-15 12:17:22 +00:00
DivergenceAnalysis.cpp
DominanceFrontier.cpp
DomPrinter.cpp
InstCount.cpp
InstructionSimplify.cpp	[InstSimplify] Handle some overflow intrinsics in InstSimplify	2015-05-22 03:56:46 +00:00
Interval.cpp
IntervalPartition.cpp
IteratedDominanceFrontier.cpp
IVUsers.cpp
LazyCallGraph.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp
LLVMBuild.txt
Loads.cpp
LoopAccessAnalysis.cpp	[LoopAccesses] If shouldRetryWithRuntimeCheck, reset InterestingDependences	2015-05-18 15:37:03 +00:00
LoopInfo.cpp	Add llvm::all_of which wraps std::all_of.	2015-05-13 22:19:13 +00:00
LoopPass.cpp
Makefile
MemDepPrinter.cpp
MemDerefPrinter.cpp	Test commit. Fix typo in MemDerefPrinter.cpp comment.	2015-05-21 11:57:38 +00:00
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PHITransAddr.cpp
PostDominators.cpp
PtrUseVisitor.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	[ScalarEvolution] refactor: extract interface getGEPExpr	2015-05-18 17:03:25 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
ScalarEvolutionNormalization.cpp
ScopedNoAliasAA.cpp
SparsePropagation.cpp
StratifiedSets.h
TargetLibraryInfo.cpp	Populate list of vectorizable functions for Accelerate library.	2015-05-07 17:11:51 +00:00
TargetTransformInfo.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	Reapply r237539 with a fix for the Chromium build.	2015-05-20 18:41:25 +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))

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