forked from OSchip/llvm-project
51ad99d2c5
This new version is much more aggressive about doing "full" reduction in cases where it reduces register pressure, and also more aggressive about rewriting induction variables to count down (or up) to zero when doing so reduces register pressure. It currently uses fairly simplistic algorithms for finding reuse opportunities, but it introduces a new framework allows it to combine multiple strategies at once to form hybrid solutions, instead of doing all full-reduction or all base+index. llvm-svn: 94061 |
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| .. | ||
| IPA | ||
| AliasAnalysis.cpp | ||
| AliasAnalysisCounter.cpp | ||
| AliasAnalysisEvaluator.cpp | ||
| AliasDebugger.cpp | ||
| AliasSetTracker.cpp | ||
| Analysis.cpp | ||
| BasicAliasAnalysis.cpp | ||
| CFGPrinter.cpp | ||
| CMakeLists.txt | ||
| CaptureTracking.cpp | ||
| ConstantFolding.cpp | ||
| DbgInfoPrinter.cpp | ||
| DebugInfo.cpp | ||
| DomPrinter.cpp | ||
| IVUsers.cpp | ||
| InlineCost.cpp | ||
| InstCount.cpp | ||
| InstructionSimplify.cpp | ||
| Interval.cpp | ||
| IntervalPartition.cpp | ||
| LazyValueInfo.cpp | ||
| LibCallAliasAnalysis.cpp | ||
| LibCallSemantics.cpp | ||
| LiveValues.cpp | ||
| LoopDependenceAnalysis.cpp | ||
| LoopInfo.cpp | ||
| LoopPass.cpp | ||
| Makefile | ||
| MemoryBuiltins.cpp | ||
| MemoryDependenceAnalysis.cpp | ||
| PHITransAddr.cpp | ||
| PointerTracking.cpp | ||
| PostDominators.cpp | ||
| ProfileEstimatorPass.cpp | ||
| ProfileInfo.cpp | ||
| ProfileInfoLoader.cpp | ||
| ProfileInfoLoaderPass.cpp | ||
| ProfileVerifierPass.cpp | ||
| README.txt | ||
| ScalarEvolution.cpp | ||
| ScalarEvolutionAliasAnalysis.cpp | ||
| ScalarEvolutionExpander.cpp | ||
| SparsePropagation.cpp | ||
| Trace.cpp | ||
| ValueTracking.cpp | ||
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.
//===---------------------------------------------------------------------===//