llvm-6502

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

History

Chris Lattner b31189f262 fix PR5978 by peeling the loop so that we avoid shifting the result int by 8 for the first byte. While normally harmless, if the result is smaller than a byte, this shift is invalid. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93018 91177308-0d34-0410-b5e6-96231b3b80d8		2010-01-08 19:02:23 +00:00
..
IPA	Change dbgs() back to errs() for assert messages as Chris requested.	2009-12-23 23:14:41 +00:00
AliasAnalysis.cpp	Partially address a README by having functionattrs consider calls to	2010-01-06 08:45:52 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp
CaptureTracking.cpp
CFGPrinter.cpp
CMakeLists.txt
ConstantFolding.cpp	fix PR5978 by peeling the loop so that we avoid shifting the	2010-01-08 19:02:23 +00:00
DbgInfoPrinter.cpp	Remove dead debug info intrinsics.	2010-01-05 01:10:40 +00:00
DebugInfo.cpp	Convert a ton of simple integer type equality tests to the new predicate.	2010-01-05 20:07:06 +00:00
DomPrinter.cpp
InlineCost.cpp
InstCount.cpp	Change dbgs() back to errs() as Chris requested.	2009-12-23 23:29:28 +00:00
InstructionSimplify.cpp
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
LiveValues.cpp
LoopDependenceAnalysis.cpp
LoopInfo.cpp	Restore dump() methods to Loop and MachineLoop.	2010-01-05 21:08:02 +00:00
LoopPass.cpp
Makefile
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp
PHITransAddr.cpp	Change dbgs() back to errs() as Chris requested.	2009-12-23 23:27:15 +00:00
PointerTracking.cpp
PostDominators.cpp
ProfileEstimatorPass.cpp
ProfileInfo.cpp	Change dbgs() back to errs() for assert messages as Chris requested.	2009-12-23 22:59:29 +00:00
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp	Change dbgs() back to errs() for assert messages as Chris requested.	2009-12-23 23:00:50 +00:00
ProfileVerifierPass.cpp
README.txt
ScalarEvolution.cpp
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
SparsePropagation.cpp
Trace.cpp
ValueTracking.cpp	teach ComputeNumSignBits to look through PHI nodes.	2010-01-07 23:44:37 +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.

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