llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-09-30 19:55:11 +00:00

History

Dan Gohman f042660197 Move Instruction::isSafeToSpeculativelyExecute out of VMCore and into Analysis as a standalone function, since there's no need for it to be in VMCore. Also, update it to use isKnownNonZero and other goodies available in Analysis, making it more precise, enabling more aggressive optimization. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146610 91177308-0d34-0410-b5e6-96231b3b80d8		2011-12-14 23:49:11 +00:00
..
IPA	LLVMBuild: Remove trailing newline, which irked me.	2011-12-12 19:48:00 +00:00
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp	Refactor code to use new attribute getters on CallSite for NoCapture and ByVal.	2011-11-20 19:09:04 +00:00
BlockFrequencyInfo.cpp
BranchProbabilityInfo.cpp	Remove all remaining uses of Value::getNameStr().	2011-11-15 16:27:03 +00:00
CaptureTracking.cpp	Fix crasher in GVN due to my recent capture tracking changes.	2011-11-21 19:42:56 +00:00
CFGPrinter.cpp	Remove all remaining uses of Value::getNameStr().	2011-11-15 16:27:03 +00:00
CMakeLists.txt	build/CMake: Finish removal of add_llvm_library_dependencies.	2011-11-29 19:25:30 +00:00
ConstantFolding.cpp	Switch llvm.cttz and llvm.ctlz to accept a second i1 parameter which	2011-12-12 04:26:04 +00:00
DbgInfoPrinter.cpp
DebugInfo.cpp
DIBuilder.cpp	Fix typo in comment.	2011-11-09 22:45:04 +00:00
DominanceFrontier.cpp
DomPrinter.cpp
InlineCost.cpp
InstCount.cpp
InstructionSimplify.cpp	Add support for vectors of pointers.	2011-12-05 06:29:09 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LazyValueInfo.cpp	Clear the new cache.	2011-12-03 15:19:55 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp	Fix a few more places where TargetData/TargetLibraryInfo is not being passed.	2011-12-02 01:26:24 +00:00
LLVMBuild.txt	LLVMBuild: Introduce a common section which currently has a list of the	2011-12-12 22:45:54 +00:00
Loads.cpp
LoopDependenceAnalysis.cpp
LoopInfo.cpp	Move Instruction::isSafeToSpeculativelyExecute out of VMCore and	2011-12-14 23:49:11 +00:00
LoopPass.cpp
Makefile
MemDepPrinter.cpp	Fix a stupid typo in MemDepPrinter.	2011-12-14 02:54:39 +00:00
MemoryBuiltins.cpp	Validate the return type when checking if a function is malloc.	2011-11-23 17:58:47 +00:00
MemoryDependenceAnalysis.cpp	Fix crasher in GVN due to my recent capture tracking changes.	2011-11-21 19:42:56 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PathNumbering.cpp
PathProfileInfo.cpp
PathProfileVerifier.cpp	Remove all remaining uses of Value::getNameStr().	2011-11-15 16:27:03 +00:00
PHITransAddr.cpp	Move Instruction::isSafeToSpeculativelyExecute out of VMCore and	2011-12-14 23:49:11 +00:00
PostDominators.cpp
ProfileEstimatorPass.cpp	Remove all remaining uses of Value::getNameStr().	2011-11-15 16:27:03 +00:00
ProfileInfo.cpp
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp	Remove all remaining uses of Value::getNameStr().	2011-11-15 16:27:03 +00:00
ProfileVerifierPass.cpp	Move code into anonymous namespaces.	2011-11-26 23:01:57 +00:00
README.txt
RegionInfo.cpp	Missed some users of Value::getNameStr.	2011-11-15 18:30:06 +00:00
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp	Fix a few more places where TargetData/TargetLibraryInfo is not being passed.	2011-12-02 01:26:24 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp	LSR: Fold redundant bitcasts on-the-fly.	2011-12-14 22:07:19 +00:00
ScalarEvolutionNormalization.cpp
SparsePropagation.cpp	Remove all remaining uses of Value::getNameStr().	2011-11-15 16:27:03 +00:00
Trace.cpp	Remove all remaining uses of Value::getNameStr().	2011-11-15 16:27:03 +00:00
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	Move Instruction::isSafeToSpeculativelyExecute out of VMCore and	2011-12-14 23:49:11 +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))

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