llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-19 17:33:29 +00:00

History

Nick Lewycky f201a06662 Factor out the multiply analysis code in ComputeMaskedBits and apply it to the overflow checking multiply intrinsic as well. Add a test for this, updating the test from grep to FileCheck. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153028 91177308-0d34-0410-b5e6-96231b3b80d8		2012-03-18 23:28:48 +00:00
..
IPA
AliasAnalysis.cpp
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp
BlockFrequencyInfo.cpp
BranchProbabilityInfo.cpp
CaptureTracking.cpp
CFGPrinter.cpp
CMakeLists.txt	Pull the implementation of the code metrics out of the inline cost	2012-03-16 05:51:52 +00:00
CodeMetrics.cpp	Pull the implementation of the code metrics out of the inline cost	2012-03-16 05:51:52 +00:00
ConstantFolding.cpp
DbgInfoPrinter.cpp
DebugInfo.cpp	Do the right thing on NULL uint64 fields.	2012-03-16 00:21:54 +00:00
DIBuilder.cpp
DominanceFrontier.cpp
DomPrinter.cpp
InlineCost.cpp	Start removing the use of an ad-hoc 'never inline' set and instead	2012-03-16 06:10:13 +00:00
InstCount.cpp
InstructionSimplify.cpp	Type sizes and fields offsets inside structs are unsigned. This is a highly	2012-03-15 20:14:42 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp	LSR fix: Add isSimplifiedLoopNest to IVUsers analysis.	2012-03-16 03:16:56 +00:00
LazyValueInfo.cpp	llvm::SwitchInst	2012-03-11 06:09:17 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp
LLVMBuild.txt
Loads.cpp	enhance jump threading to preserve TBAA information when PRE'ing loads,	2012-03-13 18:07:41 +00:00
LoopDependenceAnalysis.cpp
LoopInfo.cpp
LoopPass.cpp
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PathNumbering.cpp
PathProfileInfo.cpp
PathProfileVerifier.cpp
PHITransAddr.cpp	Uniformize the InstructionSimplify interface by ensuring that all routines	2012-03-13 11:42:19 +00:00
PostDominators.cpp
ProfileEstimatorPass.cpp
ProfileInfo.cpp
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp
RegionPrinter.cpp
ScalarEvolution.cpp
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
ScalarEvolutionNormalization.cpp
SparsePropagation.cpp	Taken into account Duncan's comments for r149481 dated by 2nd Feb 2012:	2012-03-08 07:06:20 +00:00
Trace.cpp
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp	Factor out the multiply analysis code in ComputeMaskedBits and apply it to the	2012-03-18 23:28:48 +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))

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