llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-19 01:34:32 +00:00

History

Duncan Sands 50ca4d37f7 Improve threading of comparisons over select instructions (spotted by my auto-simplifier). This has a big impact on Ada code, but not much else. Unfortunately the impact is mostly negative! This is due to PR9004 (aka SCCP failing to resolve conditional branch conditions in the destination blocks of the branch), in which simple correlated expressions are not resolved but complicated ones are, so simplifying has a bad effect! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124788 91177308-0d34-0410-b5e6-96231b3b80d8		2011-02-03 09:37:39 +00:00
..
IPA	Use the new addEscapingValue callback to update GlobalsModRef when GVN adds PHIs of GEPs. For the moment,	2011-01-03 23:51:43 +00:00
AliasAnalysis.cpp	Stub out a new updating interface to AliasAnalysis, allowing stateful analyses to be informed when	2011-01-03 21:38:41 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp	Implementation of path profiling.	2011-01-29 01:09:53 +00:00
BasicAliasAnalysis.cpp	Give GetUnderlyingObject a TargetData, to keep it in sync	2011-01-24 18:53:32 +00:00
CaptureTracking.cpp
CFGPrinter.cpp
CMakeLists.txt	Implementation of path profiling.	2011-01-29 01:09:53 +00:00
ConstantFolding.cpp	Give GetUnderlyingObject a TargetData, to keep it in sync	2011-01-24 18:53:32 +00:00
DbgInfoPrinter.cpp
DebugInfo.cpp	Fix typo in comment.	2011-02-03 00:13:47 +00:00
DIBuilder.cpp	Add support to describe template value parameter in debug info.	2011-02-02 22:35:53 +00:00
DominanceFrontier.cpp	Move DominanceFrontier from VMCore to Analysis.	2011-01-18 06:06:27 +00:00
DomPrinter.cpp	split dom frontier handling stuff out to its own DominanceFrontier header,	2011-01-02 22:09:33 +00:00
InlineCost.cpp	Reapply 124275 since the Dragonegg failure was unreproducible.	2011-02-01 01:16:32 +00:00
InstCount.cpp
InstructionSimplify.cpp	Improve threading of comparisons over select instructions (spotted by my	2011-02-03 09:37:39 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp	split dom frontier handling stuff out to its own DominanceFrontier header,	2011-01-02 22:09:33 +00:00
LazyValueInfo.cpp	Teach LazyValueInfo that allocas aren't NULL. Over all of llvm-test, this saves	2011-01-15 09:16:12 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp	Give GetUnderlyingObject a TargetData, to keep it in sync	2011-01-24 18:53:32 +00:00
LiveValues.cpp	split dom frontier handling stuff out to its own DominanceFrontier header,	2011-01-02 22:09:33 +00:00
Loads.cpp
LoopDependenceAnalysis.cpp	split dom frontier handling stuff out to its own DominanceFrontier header,	2011-01-02 22:09:33 +00:00
LoopInfo.cpp
LoopPass.cpp
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp	Give GetUnderlyingObject a TargetData, to keep it in sync	2011-01-24 18:53:32 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp	Use the new addEscapingValue callback to update GlobalsModRef when GVN adds PHIs of GEPs. For the moment,	2011-01-03 23:51:43 +00:00
PathNumbering.cpp	Implementation of path profiling.	2011-01-29 01:09:53 +00:00
PathProfileInfo.cpp	Implementation of path profiling.	2011-01-29 01:09:53 +00:00
PathProfileVerifier.cpp	Implementation of path profiling.	2011-01-29 01:09:53 +00:00
PHITransAddr.cpp	split dom frontier handling stuff out to its own DominanceFrontier header,	2011-01-02 22:09:33 +00:00
PostDominators.cpp	split dom frontier handling stuff out to its own DominanceFrontier header,	2011-01-02 22:09:33 +00:00
ProfileEstimatorPass.cpp	fix PR8928 by clearing a stale map, patch by Jakub Staszak!	2011-01-24 18:36:51 +00:00
ProfileInfo.cpp	Null initialize a few variables flagged by	2011-01-23 17:05:06 +00:00
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp
README.txt
RegionInfo.cpp	Add single entry / single exit accessors.	2011-01-13 23:18:04 +00:00
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	Fix memory corruption. If one of the SCEV creation functions calls another but	2011-01-26 08:40:22 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
ScalarEvolutionNormalization.cpp
SparsePropagation.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	Add a m_SignBit pattern for convenience.	2011-02-01 08:50:33 +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))

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