X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FAnalysis%2FMemoryDependenceAnalysis.h;h=d7d795e08a16eaa9469b5b0228a9b10b57008d5c;hb=b1d7a5d1146c30a54002b7ab49daf024e3174b95;hp=10aeb290c84941cd4e055d4c450d9ced22188178;hpb=396a4a55e535728e2023aa331401c1a2b782cb9a;p=oota-llvm.git diff --git a/include/llvm/Analysis/MemoryDependenceAnalysis.h b/include/llvm/Analysis/MemoryDependenceAnalysis.h index 10aeb290c84..d7d795e08a1 100644 --- a/include/llvm/Analysis/MemoryDependenceAnalysis.h +++ b/include/llvm/Analysis/MemoryDependenceAnalysis.h @@ -18,6 +18,7 @@ #include "llvm/Pass.h" #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/OwningPtr.h" #include "llvm/ADT/PointerIntPair.h" namespace llvm { @@ -25,17 +26,48 @@ namespace llvm { class FunctionPass; class Instruction; class CallSite; + class AliasAnalysis; + class TargetData; + class MemoryDependenceAnalysis; + class PredIteratorCache; /// MemDepResult - A memory dependence query can return one of three different - /// answers: - /// Normal : The query is dependent on a specific instruction. - /// NonLocal: The query does not depend on anything inside this block, but - /// we haven't scanned beyond the block to find out what. - /// None : The query does not depend on anything: we found the entry - /// block or the allocation site of the memory. + /// answers, described below. class MemDepResult { enum DepType { - Invalid = 0, Normal, NonLocal, None + /// Invalid - Clients of MemDep never see this. + Invalid = 0, + + /// Clobber - This is a dependence on the specified instruction which + /// clobbers the desired value. The pointer member of the MemDepResult + /// pair holds the instruction that clobbers the memory. For example, + /// this occurs when we see a may-aliased store to the memory location we + /// care about. + Clobber, + + /// Def - This is a dependence on the specified instruction which + /// defines/produces the desired memory location. The pointer member of + /// the MemDepResult pair holds the instruction that defines the memory. + /// Cases of interest: + /// 1. This could be a load or store for dependence queries on + /// load/store. The value loaded or stored is the produced value. + /// Note that the pointer operand may be different than that of the + /// queried pointer due to must aliases and phi translation. Note + /// that the def may not be the same type as the query, the pointers + /// may just be must aliases. + /// 2. For loads and stores, this could be an allocation instruction. In + /// this case, the load is loading an undef value or a store is the + /// first store to (that part of) the allocation. + /// 3. Dependence queries on calls return Def only when they are + /// readonly calls with identical callees and no intervening + /// clobbers. No validation is done that the operands to the calls + /// are the same. + Def, + + /// NonLocal - This marker indicates that the query has no dependency in + /// the specified block. To find out more, the client should query other + /// predecessor blocks. + NonLocal }; typedef PointerIntPair PairTy; PairTy Value; @@ -45,85 +77,113 @@ namespace llvm { /// get methods: These are static ctor methods for creating various /// MemDepResult kinds. - static MemDepResult get(Instruction *Inst) { - return MemDepResult(PairTy(Inst, Normal)); + static MemDepResult getDef(Instruction *Inst) { + return MemDepResult(PairTy(Inst, Def)); + } + static MemDepResult getClobber(Instruction *Inst) { + return MemDepResult(PairTy(Inst, Clobber)); } static MemDepResult getNonLocal() { return MemDepResult(PairTy(0, NonLocal)); } - static MemDepResult getNone() { - return MemDepResult(PairTy(0, None)); - } - /// isNormal - Return true if this MemDepResult represents a query that is - /// a normal instruction dependency. - bool isNormal() const { return Value.getInt() == Normal; } + /// isClobber - Return true if this MemDepResult represents a query that is + /// a instruction clobber dependency. + bool isClobber() const { return Value.getInt() == Clobber; } + + /// isDef - Return true if this MemDepResult represents a query that is + /// a instruction definition dependency. + bool isDef() const { return Value.getInt() == Def; } /// isNonLocal - Return true if this MemDepResult represents an query that /// is transparent to the start of the block, but where a non-local hasn't /// been done. bool isNonLocal() const { return Value.getInt() == NonLocal; } - /// isNone - Return true if this MemDepResult represents a query that - /// doesn't depend on any instruction. - bool isNone() const { return Value.getInt() == None; } - /// getInst() - If this is a normal dependency, return the instruction that /// is depended on. Otherwise, return null. - Instruction *getInst() const { return isNormal() ? Value.getPointer() : 0; } + Instruction *getInst() const { return Value.getPointer(); } - bool operator==(const MemDepResult &M) { return M.Value == Value; } - bool operator!=(const MemDepResult &M) { return M.Value != Value; } + bool operator==(const MemDepResult &M) const { return Value == M.Value; } + bool operator!=(const MemDepResult &M) const { return Value != M.Value; } + bool operator<(const MemDepResult &M) const { return Value < M.Value; } + bool operator>(const MemDepResult &M) const { return Value > M.Value; } + private: + friend class MemoryDependenceAnalysis; + /// Dirty - Entries with this marker occur in a LocalDeps map or + /// NonLocalDeps map when the instruction they previously referenced was + /// removed from MemDep. In either case, the entry may include an + /// instruction pointer. If so, the pointer is an instruction in the + /// block where scanning can start from, saving some work. + /// + /// In a default-constructed MemDepResult object, the type will be Dirty + /// and the instruction pointer will be null. + /// + + /// isDirty - Return true if this is a MemDepResult in its dirty/invalid. + /// state. + bool isDirty() const { return Value.getInt() == Invalid; } + + static MemDepResult getDirty(Instruction *Inst) { + return MemDepResult(PairTy(Inst, Invalid)); + } }; /// MemoryDependenceAnalysis - This is an analysis that determines, for a /// given memory operation, what preceding memory operations it depends on. /// It builds on alias analysis information, and tries to provide a lazy, /// caching interface to a common kind of alias information query. + /// + /// The dependency information returned is somewhat unusual, but is pragmatic. + /// If queried about a store or call that might modify memory, the analysis + /// will return the instruction[s] that may either load from that memory or + /// store to it. If queried with a load or call that can never modify memory, + /// the analysis will return calls and stores that might modify the pointer, + /// but generally does not return loads unless a) they are volatile, or + /// b) they load from *must-aliased* pointers. Returning a dependence on + /// must-alias'd pointers instead of all pointers interacts well with the + /// internal caching mechanism. + /// class MemoryDependenceAnalysis : public FunctionPass { - /// DepType - This enum is used to indicate what flavor of dependence this - /// is. If the type is Normal, there is an associated instruction pointer. - enum DepType { - /// Dirty - Entries with this marker may come in two forms, depending on - /// whether they are in a LocalDeps map or NonLocalDeps map. In either - /// case, this marker indicates that the cached value has been invalidated - /// by a removeInstruction call. - /// - /// If in the LocalDeps map, the Instruction field will indicate the place - /// in the current block to start scanning. If in the non-localdeps map, - /// the instruction will be null. - /// - /// In a default-constructed DepResultTy object, the type will be Dirty - /// and the instruction pointer will be null. - /// - /// FIXME: Why not add a scanning point for the non-local deps map??? - Dirty = 0, - - /// Normal - This is a normal instruction dependence. The pointer member - /// of the DepResultTy pair holds the instruction. - Normal, - - /// None - This dependence type indicates that the query does not depend - /// on any instructions, either because it scanned to the start of the - /// function or it scanned to the definition of the memory - /// (alloca/malloc). - None, - - /// NonLocal - This marker indicates that the query has no dependency in - /// the specified block. To find out more, the client should query other - /// predecessor blocks. - NonLocal - }; - typedef PointerIntPair DepResultTy; - // A map from instructions to their dependency. - typedef DenseMap LocalDepMapType; + typedef DenseMap LocalDepMapType; LocalDepMapType LocalDeps; + public: + typedef std::pair NonLocalDepEntry; + typedef std::vector NonLocalDepInfo; + private: + /// ValueIsLoadPair - This is a pair where the bool is true if + /// the dependence is a read only dependence, false if read/write. + typedef PointerIntPair ValueIsLoadPair; + + /// BBSkipFirstBlockPair - This pair is used when caching information for a + /// block. If the pointer is null, the cache value is not a full query that + /// starts at the specified block. If non-null, the bool indicates whether + /// or not the contents of the block was skipped. + typedef PointerIntPair BBSkipFirstBlockPair; + + /// CachedNonLocalPointerInfo - This map stores the cached results of doing + /// a pointer lookup at the bottom of a block. The key of this map is the + /// pointer+isload bit, the value is a list of result> mappings. + typedef DenseMap > CachedNonLocalPointerInfo; + CachedNonLocalPointerInfo NonLocalPointerDeps; + + // A map from instructions to their non-local pointer dependencies. + typedef DenseMap > ReverseNonLocalPtrDepTy; + ReverseNonLocalPtrDepTy ReverseNonLocalPtrDeps; + + + /// PerInstNLInfo - This is the instruction we keep for each cached access + /// that we have for an instruction. The pointer is an owning pointer and + /// the bool indicates whether we have any dirty bits in the set. + typedef std::pair PerInstNLInfo; + // A map from instructions to their non-local dependencies. - // FIXME: DENSEMAP of DENSEMAP not a great idea. - typedef DenseMap > NonLocalDepMapType; + typedef DenseMap NonLocalDepMapType; + NonLocalDepMapType NonLocalDeps; // A reverse mapping from dependencies to the dependees. This is @@ -135,83 +195,91 @@ namespace llvm { // A reverse mapping form dependencies to the non-local dependees. ReverseDepMapType ReverseNonLocalDeps; + /// Current AA implementation, just a cache. + AliasAnalysis *AA; + TargetData *TD; + OwningPtr PredCache; public: - MemoryDependenceAnalysis() : FunctionPass(&ID) {} + MemoryDependenceAnalysis(); + ~MemoryDependenceAnalysis(); static char ID; - /// Pass Implementation stuff. This doesn't do any analysis. - /// - bool runOnFunction(Function &) {return false; } + /// Pass Implementation stuff. This doesn't do any analysis eagerly. + bool runOnFunction(Function &); /// Clean up memory in between runs - void releaseMemory() { - LocalDeps.clear(); - NonLocalDeps.clear(); - ReverseLocalDeps.clear(); - ReverseNonLocalDeps.clear(); - } - + void releaseMemory(); + /// getAnalysisUsage - Does not modify anything. It uses Value Numbering /// and Alias Analysis. /// virtual void getAnalysisUsage(AnalysisUsage &AU) const; /// getDependency - Return the instruction on which a memory operation - /// depends. + /// depends. See the class comment for more details. It is illegal to call + /// this on non-memory instructions. MemDepResult getDependency(Instruction *QueryInst); - /// getDependencyFrom - Return the instruction on which the memory operation - /// 'QueryInst' depends. This starts scanning from the instruction before - /// the position indicated by ScanIt. - MemDepResult getDependencyFrom(Instruction *QueryInst, - BasicBlock::iterator ScanIt, BasicBlock *BB); - - - /// getNonLocalDependency - Perform a full dependency query for the - /// specified instruction, returning the set of blocks that the value is + /// getNonLocalCallDependency - Perform a full dependency query for the + /// specified call, returning the set of blocks that the value is /// potentially live across. The returned set of results will include a /// "NonLocal" result for all blocks where the value is live across. /// - /// This method assumes the instruction returns a "nonlocal" dependency + /// This method assumes the instruction returns a "NonLocal" dependency /// within its own block. - void getNonLocalDependency(Instruction *QueryInst, - SmallVectorImpl > &Result); + /// + /// This returns a reference to an internal data structure that may be + /// invalidated on the next non-local query or when an instruction is + /// removed. Clients must copy this data if they want it around longer than + /// that. + const NonLocalDepInfo &getNonLocalCallDependency(CallSite QueryCS); + + + /// getNonLocalPointerDependency - Perform a full dependency query for an + /// access to the specified (non-volatile) memory location, returning the + /// set of instructions that either define or clobber the value. + /// + /// This method assumes the pointer has a "NonLocal" dependency within BB. + void getNonLocalPointerDependency(Value *Pointer, bool isLoad, + BasicBlock *BB, + SmallVectorImpl &Result); /// removeInstruction - Remove an instruction from the dependence analysis, /// updating the dependence of instructions that previously depended on it. void removeInstruction(Instruction *InstToRemove); - /// dropInstruction - Remove an instruction from the analysis, making - /// absolutely conservative assumptions when updating the cache. This is - /// useful, for example when an instruction is changed rather than removed. - void dropInstruction(Instruction *InstToDrop); + /// invalidateCachedPointerInfo - This method is used to invalidate cached + /// information about the specified pointer, because it may be too + /// conservative in memdep. This is an optional call that can be used when + /// the client detects an equivalence between the pointer and some other + /// value and replaces the other value with ptr. This can make Ptr available + /// in more places that cached info does not necessarily keep. + void invalidateCachedPointerInfo(Value *Ptr); private: - DepResultTy ConvFromResult(MemDepResult R) { - if (Instruction *I = R.getInst()) - return DepResultTy(I, Normal); - if (R.isNonLocal()) - return DepResultTy(0, NonLocal); - assert(R.isNone() && "Unknown MemDepResult!"); - return DepResultTy(0, None); - } - - MemDepResult ConvToResult(DepResultTy R) { - if (R.getInt() == Normal) - return MemDepResult::get(R.getPointer()); - if (R.getInt() == NonLocal) - return MemDepResult::getNonLocal(); - assert(R.getInt() == None && "Unknown MemDepResult!"); - return MemDepResult::getNone(); - } + MemDepResult getPointerDependencyFrom(Value *Pointer, uint64_t MemSize, + bool isLoad, + BasicBlock::iterator ScanIt, + BasicBlock *BB); + MemDepResult getCallSiteDependencyFrom(CallSite C, bool isReadOnlyCall, + BasicBlock::iterator ScanIt, + BasicBlock *BB); + bool getNonLocalPointerDepFromBB(Value *Pointer, uint64_t Size, + bool isLoad, BasicBlock *BB, + SmallVectorImpl &Result, + DenseMap &Visited, + bool SkipFirstBlock = false); + MemDepResult GetNonLocalInfoForBlock(Value *Pointer, uint64_t PointeeSize, + bool isLoad, BasicBlock *BB, + NonLocalDepInfo *Cache, + unsigned NumSortedEntries); + + void RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair P); /// verifyRemoved - Verify that the specified instruction does not occur /// in our internal data structures. void verifyRemoved(Instruction *Inst) const; - MemDepResult getCallSiteDependency(CallSite C, BasicBlock::iterator ScanIt, - BasicBlock *BB); }; } // End llvm namespace