llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-11-03 14:08:57 +00:00

History

Dan Gohman b92654d9c9 Fix ScalarEvolution's "exhaustive" trip count evaluation code to avoid assuming that loops are in canonical form, as ScalarEvolution doesn't depend on LoopSimplify itself. Also, with indirectbr not all loops can be simplified. This fixes PR7416. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106389 91177308-0d34-0410-b5e6-96231b3b80d8		2010-06-19 14:17:24 +00:00
..
IPA	Create new accessors to get arguments for call/invoke instructions. It breaks	2010-06-07 19:05:06 +00:00
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp	Fix AliasDebugger to be aware of operand values too.	2010-05-28 22:31:51 +00:00
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp
CaptureTracking.cpp
CFGPrinter.cpp
CMakeLists.txt	Move FindAvailableLoadedValue isSafeToLoadUnconditionally out of	2010-05-28 16:19:17 +00:00
ConstantFolding.cpp	Eliminate unnecessary uses of getZExtValue().	2010-06-18 14:22:04 +00:00
DbgInfoPrinter.cpp
DebugInfo.cpp	Check function pointer first, before comparing function names.	2010-06-16 06:42:02 +00:00
DomPrinter.cpp
InlineCost.cpp	Pulled CodeMetrics out of InlineCost.h and made it a bit more general, so it can be reused from PartialSpecializationCost	2010-06-09 15:11:37 +00:00
InstCount.cpp
InstructionSimplify.cpp
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp	Fix the noalias checking so that it doesn't worry about	2010-06-01 20:51:40 +00:00
LiveValues.cpp
Loads.cpp	Move FindAvailableLoadedValue isSafeToLoadUnconditionally out of	2010-05-28 16:19:17 +00:00
LoopDependenceAnalysis.cpp
LoopInfo.cpp
LoopPass.cpp
Makefile
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp
ModuleDebugInfoPrinter.cpp
PHITransAddr.cpp
PointerTracking.cpp
PostDominators.cpp
ProfileEstimatorPass.cpp
ProfileInfo.cpp
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp
README.txt
ScalarEvolution.cpp	Fix ScalarEvolution's "exhaustive" trip count evaluation code to avoid	2010-06-19 14:17:24 +00:00
ScalarEvolutionAliasAnalysis.cpp	Fix a typo in a comment.	2010-06-18 00:53:08 +00:00
ScalarEvolutionExpander.cpp	Factor out duplicated code for reusing and inserting casts into	2010-06-19 13:25:23 +00:00
ScalarEvolutionNormalization.cpp	Fix normalization and de-normalization of non-affine SCEVs.	2010-06-04 19:16:34 +00:00
SparsePropagation.cpp
Trace.cpp
ValueTracking.cpp

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))

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