llvm-6502/lib/Analysis
Dan Gohman cc1ffc6652 Update this comment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132202 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-27 18:42:33 +00:00
..
IPA Fix a source of non determinism in FindUsedTypes, use a SetVector instead of a 2011-05-13 05:20:42 +00:00
AliasAnalysis.cpp When analyzing functions known to only access argument pointees, 2011-04-27 18:39:03 +00:00
AliasAnalysisCounter.cpp
AliasAnalysisEvaluator.cpp
AliasDebugger.cpp
AliasSetTracker.cpp PR9604; try to deal with RAUW updates correctly in the AST. I'm not convinced 2011-04-09 06:55:46 +00:00
Analysis.cpp remove postdom frontiers, because it is dead. Forward dom frontiers are 2011-04-05 21:57:17 +00:00
BasicAliasAnalysis.cpp Make DecomposeGEPExpression check SimplifyInstruction only 2011-05-24 18:24:08 +00:00
CaptureTracking.cpp Don't include Operator.h from InstrTypes.h. 2011-04-11 09:35:34 +00:00
CFGPrinter.cpp
CMakeLists.txt
ConstantFolding.cpp implement PR9315, constant folding exp2 in terms of pow (since hosts without 2011-05-22 22:22:35 +00:00
DbgInfoPrinter.cpp
DebugInfo.cpp
DIBuilder.cpp Use llvm.dbg.cu named metadata to collect compile units. 2011-05-03 16:18:28 +00:00
DominanceFrontier.cpp
DomPrinter.cpp
InlineCost.cpp Change condition for determining whether a function is small for inlining metrics so that very long functions 2011-05-24 20:22:24 +00:00
InstCount.cpp
InstructionSimplify.cpp The comparision "max(x,y)==x" is equivalent to "x>=y". Since the max is 2011-05-07 16:56:49 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp Update this comment. 2011-05-27 18:42:33 +00:00
LazyValueInfo.cpp Remove unused STL header includes. 2011-04-23 19:53:52 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp PR9214: Convert ConstantExpr::getIndices() to return an ArrayRef, plus 2011-04-13 15:22:40 +00:00
Loads.cpp Don't include Operator.h from InstrTypes.h. 2011-04-11 09:35:34 +00:00
LoopDependenceAnalysis.cpp
LoopInfo.cpp
LoopPass.cpp
Makefile
MemDepPrinter.cpp
MemoryBuiltins.cpp
MemoryDependenceAnalysis.cpp @llvm.lifetime.begin acts as a load, not @llvm.lifetime.end. 2011-05-17 00:05:49 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PathNumbering.cpp Remove unused STL header includes. 2011-04-23 19:53:52 +00:00
PathProfileInfo.cpp
PathProfileVerifier.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
PHITransAddr.cpp Don't include Operator.h from InstrTypes.h. 2011-04-11 09:35:34 +00:00
PostDominators.cpp remove postdom frontiers, because it is dead. Forward dom frontiers are 2011-04-05 21:57:17 +00:00
ProfileEstimatorPass.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
ProfileInfo.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
ProfileInfoLoader.cpp Remove unused STL header includes. 2011-04-23 19:53:52 +00:00
ProfileInfoLoaderPass.cpp
ProfileVerifierPass.cpp
README.txt
RegionInfo.cpp
RegionPass.cpp Minor change: Fix the typo in RegionPass.h and RegionPass.cpp. 2011-05-05 13:59:38 +00:00
RegionPrinter.cpp
ScalarEvolution.cpp Change a few std::maps to DenseMaps. 2011-05-09 18:44:09 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp
ScalarEvolutionNormalization.cpp
SparsePropagation.cpp
Trace.cpp
TypeBasedAliasAnalysis.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
ValueTracking.cpp Renamed llvm.x86.sse42.crc32 intrinsics; crc64 doesn't exist. 2011-05-26 23:13:19 +00:00

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))

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