llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-10-17 03:26:03 +00:00

History

Dan Gohman 7a64257f94 Just as its not safe to blindly transfer the nsw bit from an add instruction to an add scev, it's not safe to blindly transfer the inbounds flag from a gep instruction to an nsw on the scev for the gep. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107117 91177308-0d34-0410-b5e6-96231b3b80d8		2010-06-29 01:41:41 +00:00
..
IPA	Create new accessors to get arguments for call/invoke instructions. It breaks	2010-06-07 19:05:06 +00:00
AliasAnalysis.cpp	Add an Intraprocedural form of BasicAliasAnalysis, which aims to	2010-06-29 00:50:39 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp	Generalize AAEval so that it can be used both per-function and	2010-06-28 16:01:37 +00:00
AliasDebugger.cpp	Fix AliasDebugger to be aware of operand values too.	2010-05-28 22:31:51 +00:00
AliasSetTracker.cpp
Analysis.cpp
BasicAliasAnalysis.cpp	Add an Intraprocedural form of BasicAliasAnalysis, which aims to	2010-06-29 00:50:39 +00:00
CaptureTracking.cpp
CFGPrinter.cpp
CMakeLists.txt	Move FindAvailableLoadedValue isSafeToLoadUnconditionally out of	2010-05-28 16:19:17 +00:00
ConstantFolding.cpp	Eliminate unnecessary uses of getZExtValue().	2010-06-18 14:22:04 +00:00
DbgInfoPrinter.cpp
DebugInfo.cpp	Use named MDNode, llvm.dbg.sp, to collect subprogram info. This will be used to emit local variable's debug info of deleted functions.	2010-06-28 05:53:08 +00:00
DomPrinter.cpp
InlineCost.cpp	Pulled CodeMetrics out of InlineCost.h and made it a bit more general, so it can be reused from PartialSpecializationCost	2010-06-09 15:11:37 +00:00
InstCount.cpp
InstructionSimplify.cpp
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp
LazyValueInfo.cpp
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp	Fix the noalias checking so that it doesn't worry about	2010-06-01 20:51:40 +00:00
LiveValues.cpp
Loads.cpp	Move FindAvailableLoadedValue isSafeToLoadUnconditionally out of	2010-05-28 16:19:17 +00:00
LoopDependenceAnalysis.cpp
LoopInfo.cpp
LoopPass.cpp
Makefile
MemoryBuiltins.cpp	minor enhancement to llvm::isFreeCall API: return CallInst; no functional change	2010-06-23 21:51:12 +00:00
MemoryDependenceAnalysis.cpp	use the new isFreeCall API and ArgOperand accessors	2010-06-23 22:48:06 +00:00
ModuleDebugInfoPrinter.cpp	Add a simple module-level debug info printer. It just sets up a	2010-05-07 16:22:32 +00:00
PHITransAddr.cpp
PointerTracking.cpp
PostDominators.cpp
ProfileEstimatorPass.cpp
ProfileInfo.cpp
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp
README.txt
ScalarEvolution.cpp	Just as its not safe to blindly transfer the nsw bit from an add	2010-06-29 01:41:41 +00:00
ScalarEvolutionAliasAnalysis.cpp	Fix a typo in a comment.	2010-06-18 00:53:08 +00:00
ScalarEvolutionExpander.cpp	Use A.append(...) instead of A.insert(A.end(), ...) when A is a	2010-06-21 19:47:52 +00:00
ScalarEvolutionNormalization.cpp	Fix normalization and de-normalization of non-affine SCEVs.	2010-06-04 19:16:34 +00:00
SparsePropagation.cpp
Trace.cpp
ValueTracking.cpp	use ArgOperand accessors	2010-06-23 23:38:07 +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))

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