llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-10-07 20:57:12 +00:00

History

Chris Lattner eafc5cb80d add uadd_ov/usub_ov to apint, consolidate constant folding logic to use the new APInt methods. Among other things this implements rdar://8501501 - llvm.smul.with.overflow.i32 should constant fold which comes from "clang -ftrapv", originally brought to my attention from PR8221. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116457 91177308-0d34-0410-b5e6-96231b3b80d8		2010-10-14 00:05:07 +00:00
..
IPA	Analysis groups need to initialize their default implementations.	2010-10-13 21:49:58 +00:00
AliasAnalysis.cpp	Analysis groups need to initialize their default implementations.	2010-10-13 21:49:58 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
AliasDebugger.cpp
AliasSetTracker.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
Analysis.cpp
BasicAliasAnalysis.cpp
CaptureTracking.cpp
CFGPrinter.cpp
CMakeLists.txt
ConstantFolding.cpp	add uadd_ov/usub_ov to apint, consolidate constant folding	2010-10-14 00:05:07 +00:00
DbgInfoPrinter.cpp
DebugInfo.cpp
DomPrinter.cpp
InlineCost.cpp
InstCount.cpp
InstructionSimplify.cpp
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
LiveValues.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
Loads.cpp
LoopDependenceAnalysis.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
LoopInfo.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
LoopPass.cpp
Makefile
MemDepPrinter.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
ModuleDebugInfoPrinter.cpp
PHITransAddr.cpp
PostDominators.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
ProfileEstimatorPass.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
ProfileInfo.cpp	Analysis groups need to initialize their default implementations.	2010-10-13 21:49:58 +00:00
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
README.txt
RegionInfo.cpp	Add Region::isTopLevelRegion().	2010-10-13 11:02:44 +00:00
RegionPrinter.cpp
ScalarEvolution.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
ScalarEvolutionAliasAnalysis.cpp	Begin adding static dependence information to passes, which will allow us to	2010-10-12 19:48:12 +00:00
ScalarEvolutionExpander.cpp
ScalarEvolutionNormalization.cpp
SparsePropagation.cpp
Trace.cpp
TypeBasedAliasAnalysis.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))

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