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LLVM
3.7.0
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DependenceAnalysis - This class is the main dependence-analysis driver. More...
#include <DependenceAnalysis.h>
Public Member Functions | |
| std::unique_ptr< Dependence > | depends (Instruction *Src, Instruction *Dst, bool PossiblyLoopIndependent) |
| depends - Tests for a dependence between the Src and Dst instructions. More... | |
| const SCEV * | getSplitIteration (const Dependence &Dep, unsigned Level) |
| getSplitIteration - Give a dependence that's splittable at some particular level, return the iteration that should be used to split the loop. More... | |
| DependenceAnalysis () | |
| bool | runOnFunction (Function &F) override |
| runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass. More... | |
| void | releaseMemory () override |
| releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memory when it is no longer needed. More... | |
| void | getAnalysisUsage (AnalysisUsage &) const override |
| getAnalysisUsage - This function should be overriden by passes that need analysis information to do their job. More... | |
| void | print (raw_ostream &, const Module *=nullptr) const override |
| print - Print out the internal state of the pass. More... | |
Public Member Functions inherited from llvm::FunctionPass | |
| FunctionPass (char &pid) | |
| Pass * | createPrinterPass (raw_ostream &O, const std::string &Banner) const override |
| createPrinterPass - Get a function printer pass. More... | |
| void | assignPassManager (PMStack &PMS, PassManagerType T) override |
| Find appropriate Function Pass Manager or Call Graph Pass Manager in the PM Stack and add self into that manager. More... | |
| PassManagerType | getPotentialPassManagerType () const override |
| Return what kind of Pass Manager can manage this pass. More... | |
Public Member Functions inherited from llvm::Pass | |
| Pass (PassKind K, char &pid) | |
| virtual | ~Pass () |
| PassKind | getPassKind () const |
| virtual const char * | getPassName () const |
| getPassName - Return a nice clean name for a pass. More... | |
| AnalysisID | getPassID () const |
| getPassID - Return the PassID number that corresponds to this pass. More... | |
| virtual bool | doInitialization (Module &) |
| doInitialization - Virtual method overridden by subclasses to do any necessary initialization before any pass is run. More... | |
| virtual bool | doFinalization (Module &) |
| doFinalization - Virtual method overriden by subclasses to do any necessary clean up after all passes have run. More... | |
| void | dump () const |
| virtual void | preparePassManager (PMStack &) |
| Check if available pass managers are suitable for this pass or not. More... | |
| void | setResolver (AnalysisResolver *AR) |
| AnalysisResolver * | getResolver () const |
| virtual void * | getAdjustedAnalysisPointer (AnalysisID ID) |
| getAdjustedAnalysisPointer - This method is used when a pass implements an analysis interface through multiple inheritance. More... | |
| virtual ImmutablePass * | getAsImmutablePass () |
| virtual PMDataManager * | getAsPMDataManager () |
| virtual void | verifyAnalysis () const |
| verifyAnalysis() - This member can be implemented by a analysis pass to check state of analysis information. More... | |
| virtual void | dumpPassStructure (unsigned Offset=0) |
| template<typename AnalysisType > | |
| AnalysisType * | getAnalysisIfAvailable () const |
| getAnalysisIfAvailable<AnalysisType>() - Subclasses use this function to get analysis information that might be around, for example to update it. More... | |
| bool | mustPreserveAnalysisID (char &AID) const |
| mustPreserveAnalysisID - This method serves the same function as getAnalysisIfAvailable, but works if you just have an AnalysisID. More... | |
| template<typename AnalysisType > | |
| AnalysisType & | getAnalysis () const |
| getAnalysis<AnalysisType>() - This function is used by subclasses to get to the analysis information that they claim to use by overriding the getAnalysisUsage function. More... | |
| template<typename AnalysisType > | |
| AnalysisType & | getAnalysis (Function &F) |
| getAnalysis<AnalysisType>() - This function is used by subclasses to get to the analysis information that they claim to use by overriding the getAnalysisUsage function. More... | |
| template<typename AnalysisType > | |
| AnalysisType & | getAnalysisID (AnalysisID PI) const |
| template<typename AnalysisType > | |
| AnalysisType & | getAnalysisID (AnalysisID PI, Function &F) |
Static Public Attributes | |
| static char | ID = 0 |
Additional Inherited Members | |
Static Public Member Functions inherited from llvm::Pass | |
| static const PassInfo * | lookupPassInfo (const void *TI) |
| static const PassInfo * | lookupPassInfo (StringRef Arg) |
| static Pass * | createPass (AnalysisID ID) |
Protected Member Functions inherited from llvm::FunctionPass | |
| bool | skipOptnoneFunction (const Function &F) const |
| skipOptnoneFunction - This function has Attribute::OptimizeNone and most transformation passes should skip it. More... | |
DependenceAnalysis - This class is the main dependence-analysis driver.
Definition at line 278 of file DependenceAnalysis.h.
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inline |
Definition at line 922 of file DependenceAnalysis.h.
References llvm::PassRegistry::getPassRegistry(), and llvm::initializeDependenceAnalysisPass().
| std::unique_ptr< Dependence > DependenceAnalysis::depends | ( | Instruction * | Src, |
| Instruction * | Dst, | ||
| bool | PossiblyLoopIndependent | ||
| ) |
depends - Tests for a dependence between the Src and Dst instructions.
Returns NULL if no dependence; otherwise, returns a Dependence (or a FullDependence) with as much information as can be gleaned. The flag PossiblyLoopIndependent should be set by the caller if it appears that control flow can reach from Src to Dst without traversing a loop back edge.
Definition at line 3346 of file DependenceAnalysis.cpp.
References llvm::SmallBitVector::any(), llvm::SmallBitVector::count(), llvm::dbgs(), DEBUG, Delinearize, llvm::Dependence::DVEntry::Direction, dumpSmallBitVector(), llvm::dyn_cast(), llvm::Dependence::DVEntry::EQ, F(), llvm::SmallBitVector::find_first(), llvm::SmallBitVector::find_next(), llvm::FullDependence::getDirection(), llvm::ScalarEvolution::getElementSize(), llvm::LoopInfoBase< N, M >::getLoopFor(), llvm::User::getNumOperands(), llvm::Instruction::getParent(), llvm::GEPOperator::getPointerOperand(), getPointerOperand(), llvm::GEPOperator::getPointerOperandType(), llvm::ScalarEvolution::getSCEV(), llvm::GEPOperator::idx_begin(), llvm::GEPOperator::idx_end(), isLoadOrStore(), isLoopInvariant(), llvm_unreachable, llvm::MayAlias, llvm::Instruction::mayReadFromMemory(), llvm::Instruction::mayWriteToMemory(), llvm::MustAlias, llvm::NoAlias, llvm::Dependence::DVEntry::NONE, P, llvm::PartialAlias, llvm::SmallVectorTemplateBase< T, isPodLike< T >::value >::push_back(), llvm::SmallBitVector::reset(), llvm::SmallVectorImpl< T >::resize(), llvm::Dependence::DVEntry::Scalar, llvm::SmallBitVector::set(), llvm::SI, llvm::SmallVectorTemplateCommon< T >::size(), and underlyingObjectsAlias().
Referenced by dumpExampleDependence().
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overridevirtual |
getAnalysisUsage - This function should be overriden by passes that need analysis information to do their job.
If a pass specifies that it uses a particular analysis result to this function, it can then use the getAnalysis<AnalysisType>() function, below.
Reimplemented from llvm::Pass.
Definition at line 146 of file DependenceAnalysis.cpp.
References llvm::AnalysisUsage::addRequiredTransitive(), and llvm::AnalysisUsage::setPreservesAll().
| const SCEV * DependenceAnalysis::getSplitIteration | ( | const Dependence & | Dep, |
| unsigned | Level | ||
| ) |
getSplitIteration - Give a dependence that's splittable at some particular level, return the iteration that should be used to split the loop.
Generally, the dependence analyzer will be used to build a dependence graph for a function (basically a map from instructions to dependences). Looking for cycles in the graph shows us loops that cannot be trivially vectorized/parallelized.
We can try to improve the situation by examining all the dependences that make up the cycle, looking for ones we can break. Sometimes, peeling the first or last iteration of a loop will break dependences, and there are flags for those possibilities. Sometimes, splitting a loop at some other iteration will do the trick, and we've got a flag for that case. Rather than waste the space to record the exact iteration (since we rarely know), we provide a method that calculates the iteration. It's a drag that it must work from scratch, but wonderful in that it's possible.
Here's an example:
for (i = 0; i < 10; i++) A[i] = ... ... = A[11 - i]
There's a loop-carried flow dependence from the store to the load, found by the weak-crossing SIV test. The dependence will have a flag, indicating that the dependence can be broken by splitting the loop. Calling getSplitIteration will return 5. Splitting the loop breaks the dependence, like so:
for (i = 0; i <= 5; i++) A[i] = ... ... = A[11 - i] for (i = 6; i < 10; i++) A[i] = ... ... = A[11 - i]
breaks the dependence and allows us to vectorize/parallelize both loops.
Definition at line 3803 of file DependenceAnalysis.cpp.
References llvm::SmallBitVector::any(), llvm::SmallBitVector::count(), llvm::dbgs(), DEBUG, Delinearize, llvm::dyn_cast(), F(), llvm::SmallBitVector::find_first(), llvm::SmallBitVector::find_next(), llvm::Dependence::getDst(), llvm::ScalarEvolution::getElementSize(), llvm::LoopInfoBase< N, M >::getLoopFor(), llvm::User::getNumOperands(), llvm::Instruction::getParent(), llvm::GEPOperator::getPointerOperand(), getPointerOperand(), llvm::GEPOperator::getPointerOperandType(), llvm::ScalarEvolution::getSCEV(), llvm::Dependence::getSrc(), llvm::GEPOperator::idx_begin(), llvm::GEPOperator::idx_end(), isLoadOrStore(), isLoopInvariant(), llvm::Dependence::isSplitable(), llvm_unreachable, llvm::Instruction::mayReadFromMemory(), llvm::Instruction::mayWriteToMemory(), llvm::MustAlias, P, llvm::SmallBitVector::reset(), llvm::SmallVectorImpl< T >::resize(), llvm::SmallBitVector::set(), llvm::SI, llvm::SmallVectorTemplateCommon< T >::size(), and underlyingObjectsAlias().
Referenced by dumpExampleDependence().
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overridevirtual |
print - Print out the internal state of the pass.
This is called by Analyze to print out the contents of an analysis. Otherwise it is not necessary to implement this method. Beware that the module pointer MAY be null. This automatically forwards to a virtual function that does not provide the Module* in case the analysis doesn't need it it can just be ignored.
Reimplemented from llvm::Pass.
Definition at line 187 of file DependenceAnalysis.cpp.
References dumpExampleDependence(), and F().
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overridevirtual |
releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memory when it is no longer needed.
The default behavior of passes is to hold onto memory for the entire duration of their lifetime (which is the entire compile time). For pipelined passes, this is not a big deal because that memory gets recycled every time the pass is invoked on another program unit. For IP passes, it is more important to free memory when it is unused.
Optionally implement this function to release pass memory when it is no longer used.
Reimplemented from llvm::Pass.
Definition at line 142 of file DependenceAnalysis.cpp.
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass.
Implements llvm::FunctionPass.
Definition at line 133 of file DependenceAnalysis.cpp.
References F().
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static |
Definition at line 921 of file DependenceAnalysis.h.
1.8.6