llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-13 20:32:21 +00:00

History

David Majnemer 75ce6bba4e [PHITransAddr] Don't translate unreachable values Unreachable values may use themselves in strange ways due to their dominance property. Attempting to translate through them can lead to infinite recursion, crashing LLVM. Instead, claim that we weren't able to translate the value. This fixes PR23096. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238702 91177308-0d34-0410-b5e6-96231b3b80d8		2015-06-01 00:15:08 +00:00
..
IPA	[inliner] Fix the early-exit of the inline cost analysis to correctly	2015-05-27 02:49:05 +00:00
AliasAnalysis.cpp	Test commit: Remove unnecessary spaces.	2015-05-13 15:04:14 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp	Replace push_back(Constructor(foo)) with emplace_back(foo) for non-trivial types	2015-05-29 19:43:39 +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	Add BranchProbabilityInfo::releaseMemory to clear the Weights field.	2015-05-28 19:43:06 +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] Extend unifySubscriptType for handling coupled subscript groups.	2015-05-29 16:58:08 +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	[PHITransAddr] Don't translate unreachable values	2015-06-01 00:15:08 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PHITransAddr.cpp	[PHITransAddr] Don't translate unreachable values	2015-06-01 00:15:08 +00:00
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	Replace push_back(Constructor(foo)) with emplace_back(foo) for non-trivial types	2015-05-29 19:43:39 +00:00
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	[X86] Disable loop unrolling in loop vectorization pass when VF is 1.	2015-05-06 17:12:25 +00:00
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))

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