llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-01-31 10:34:17 +00:00

History

Sanjoy Das cd5029d001 [SCEV] Unify getUnsignedRange and getSignedRange

Summary:
This removes some duplicated code, and also helps optimization: e.g. in
the test case added, `%idx ULT 128` in `@x` is not currently optimized
to `true` by `-indvars` but will be, after this change.

The only functional change in ths commit is that for add recurrences,
ScalarEvolution::getRange will be more aggressive -- computing the
unsigned (resp. signed) range for a SCEVAddRecExpr will now look at the
NSW (resp. NUW) bits and check for signed (resp. unsigned) overflow.
This can be a strict improvement in some cases (such as the attached
test case), and should be no worse in other cases.

Reviewers: atrick, nlewycky

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D8142

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231709 91177308-0d34-0410-b5e6-96231b3b80d8

2015-03-09 21:43:43 +00:00

IPA

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AliasAnalysis.cpp

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AliasAnalysisCounter.cpp

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AliasAnalysisEvaluator.cpp

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AliasDebugger.cpp

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AliasSetTracker.cpp

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Analysis.cpp

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AssumptionCache.cpp

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BasicAliasAnalysis.cpp

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BlockFrequencyInfo.cpp

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BlockFrequencyInfoImpl.cpp

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BranchProbabilityInfo.cpp

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CaptureTracking.cpp

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CFG.cpp

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CFGPrinter.cpp

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CFLAliasAnalysis.cpp

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CGSCCPassManager.cpp

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CMakeLists.txt

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CodeMetrics.cpp

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ConstantFolding.cpp

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CostModel.cpp

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Delinearization.cpp

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DependenceAnalysis.cpp

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DominanceFrontier.cpp

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DomPrinter.cpp

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InstCount.cpp

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InstructionSimplify.cpp

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Interval.cpp

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IntervalPartition.cpp

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IVUsers.cpp

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LazyCallGraph.cpp

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LazyValueInfo.cpp

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LibCallAliasAnalysis.cpp

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LibCallSemantics.cpp

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Lint.cpp

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LLVMBuild.txt

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Loads.cpp

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LoopAccessAnalysis.cpp

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LoopInfo.cpp

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LoopPass.cpp

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Makefile

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MemDepPrinter.cpp

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MemDerefPrinter.cpp

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MemoryBuiltins.cpp

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MemoryDependenceAnalysis.cpp

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ModuleDebugInfoPrinter.cpp

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NoAliasAnalysis.cpp

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PHITransAddr.cpp

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PostDominators.cpp

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PtrUseVisitor.cpp

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README.txt

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RegionInfo.cpp

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RegionPass.cpp

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RegionPrinter.cpp

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ScalarEvolution.cpp

[SCEV] Unify getUnsignedRange and getSignedRange

2015-03-09 21:43:43 +00:00

ScalarEvolutionAliasAnalysis.cpp

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ScalarEvolutionExpander.cpp

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ScalarEvolutionNormalization.cpp

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ScopedNoAliasAA.cpp

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SparsePropagation.cpp

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StratifiedSets.h

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TargetLibraryInfo.cpp

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TargetTransformInfo.cpp

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Trace.cpp

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TypeBasedAliasAnalysis.cpp

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ValueTracking.cpp

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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))

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