X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FAnalysis%2FMemoryDependenceAnalysis.h;h=121eede1c0e419a1a61710b9990d523e1038fa5c;hb=b09c146b116359616f6cbd4c8b3328607e00ff42;hp=733e702506eed3b52e17369a891e956f9b6c5859;hpb=742f9b66822cb03af0cf7b94436e9d0288565591;p=oota-llvm.git diff --git a/include/llvm/Analysis/MemoryDependenceAnalysis.h b/include/llvm/Analysis/MemoryDependenceAnalysis.h index 733e702506e..121eede1c0e 100644 --- a/include/llvm/Analysis/MemoryDependenceAnalysis.h +++ b/include/llvm/Analysis/MemoryDependenceAnalysis.h @@ -2,107 +2,439 @@ // // The LLVM Compiler Infrastructure // -// This file was developed by the Owen Anderson and is distributed under -// the University of Illinois Open Source License. See LICENSE.TXT for details. +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // -// This file defines 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. +// This file defines the MemoryDependenceAnalysis analysis pass. // //===----------------------------------------------------------------------===// #ifndef LLVM_ANALYSIS_MEMORY_DEPENDENCE_H #define LLVM_ANALYSIS_MEMORY_DEPENDENCE_H -#include "llvm/Pass.h" -#include "llvm/Support/CallSite.h" #include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/OwningPtr.h" +#include "llvm/ADT/PointerIntPair.h" #include "llvm/ADT/SmallPtrSet.h" -#include "llvm/Support/Compiler.h" +#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/BasicBlock.h" +#include "llvm/Pass.h" +#include "llvm/Support/ValueHandle.h" namespace llvm { + class Function; + class FunctionPass; + class Instruction; + class CallSite; + class AliasAnalysis; + class DataLayout; + class MemoryDependenceAnalysis; + class PredIteratorCache; + class DominatorTree; + class PHITransAddr; + + /// MemDepResult - A memory dependence query can return one of three different + /// answers, described below. + class MemDepResult { + enum DepType { + /// 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. + /// + /// There are several cases that may be interesting here: + /// 1. Loads are clobbered by may-alias stores. + /// 2. Loads are considered clobbered by partially-aliased loads. The + /// client may choose to analyze deeper into these cases. + 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 or memory use intrinsics with identical callees + /// and no intervening clobbers. No validation is done that the + /// operands to the calls are the same. + Def, + + /// Other - This marker indicates that the query has no known dependency + /// in the specified block. More detailed state info is encoded in the + /// upper part of the pair (i.e. the Instruction*) + Other + }; + /// If DepType is "Other", the upper part of the pair + /// (i.e. the Instruction* part) is instead used to encode more detailed + /// type information as follows + enum OtherType { + /// 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 = 0x4, + /// NonFuncLocal - This marker indicates that the query has no + /// dependency in the specified function. + NonFuncLocal = 0x8, + /// Unknown - This marker indicates that the query dependency + /// is unknown. + Unknown = 0xc + }; + + typedef PointerIntPair PairTy; + PairTy Value; + explicit MemDepResult(PairTy V) : Value(V) {} + public: + MemDepResult() : Value(0, Invalid) {} + + /// get methods: These are static ctor methods for creating various + /// MemDepResult kinds. + static MemDepResult getDef(Instruction *Inst) { + assert(Inst && "Def requires inst"); + return MemDepResult(PairTy(Inst, Def)); + } + static MemDepResult getClobber(Instruction *Inst) { + assert(Inst && "Clobber requires inst"); + return MemDepResult(PairTy(Inst, Clobber)); + } + static MemDepResult getNonLocal() { + return MemDepResult( + PairTy(reinterpret_cast(NonLocal), Other)); + } + static MemDepResult getNonFuncLocal() { + return MemDepResult( + PairTy(reinterpret_cast(NonFuncLocal), Other)); + } + static MemDepResult getUnknown() { + return MemDepResult( + PairTy(reinterpret_cast(Unknown), Other)); + } + + /// isClobber - Return true if this MemDepResult represents a query that is + /// an instruction clobber dependency. + bool isClobber() const { return Value.getInt() == Clobber; } -class Function; -class FunctionPass; -class Instruction; + /// isDef - Return true if this MemDepResult represents a query that is + /// an instruction definition dependency. + bool isDef() const { return Value.getInt() == Def; } + + /// isNonLocal - Return true if this MemDepResult represents a 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() == Other + && Value.getPointer() == reinterpret_cast(NonLocal); + } + + /// isNonFuncLocal - Return true if this MemDepResult represents a query + /// that is transparent to the start of the function. + bool isNonFuncLocal() const { + return Value.getInt() == Other + && Value.getPointer() == reinterpret_cast(NonFuncLocal); + } + + /// isUnknown - Return true if this MemDepResult represents a query which + /// cannot and/or will not be computed. + bool isUnknown() const { + return Value.getInt() == Other + && Value.getPointer() == reinterpret_cast(Unknown); + } -class MemoryDependenceAnalysis : public FunctionPass { + /// getInst() - If this is a normal dependency, return the instruction that + /// is depended on. Otherwise, return null. + Instruction *getInst() const { + if (Value.getInt() == Other) return NULL; + return Value.getPointer(); + } + + 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: - // A map from instructions to their dependency, with a boolean - // flags for whether this mapping is confirmed or not - typedef DenseMap > - depMapType; - depMapType depGraphLocal; + 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)); + } + }; - // A map from instructions to their non-local dependencies. - typedef DenseMap > - nonLocalDepMapType; - nonLocalDepMapType depGraphNonLocal; + /// NonLocalDepEntry - This is an entry in the NonLocalDepInfo cache. For + /// each BasicBlock (the BB entry) it keeps a MemDepResult. + class NonLocalDepEntry { + BasicBlock *BB; + MemDepResult Result; + public: + NonLocalDepEntry(BasicBlock *bb, MemDepResult result) + : BB(bb), Result(result) {} + + // This is used for searches. + NonLocalDepEntry(BasicBlock *bb) : BB(bb) {} + + // BB is the sort key, it can't be changed. + BasicBlock *getBB() const { return BB; } - // A reverse mapping form dependencies to the dependees. This is - // used when removing instructions to keep the cache coherent. - typedef DenseMap > - reverseDepMapType; - reverseDepMapType reverseDep; + void setResult(const MemDepResult &R) { Result = R; } + + const MemDepResult &getResult() const { return Result; } - // A reverse mapping form dependencies to the non-local dependees. - reverseDepMapType reverseDepNonLocal; + bool operator<(const NonLocalDepEntry &RHS) const { + return BB < RHS.BB; + } + }; + + /// NonLocalDepResult - This is a result from a NonLocal dependence query. + /// For each BasicBlock (the BB entry) it keeps a MemDepResult and the + /// (potentially phi translated) address that was live in the block. + class NonLocalDepResult { + NonLocalDepEntry Entry; + Value *Address; + public: + NonLocalDepResult(BasicBlock *bb, MemDepResult result, Value *address) + : Entry(bb, result), Address(address) {} + // BB is the sort key, it can't be changed. + BasicBlock *getBB() const { return Entry.getBB(); } + + void setResult(const MemDepResult &R, Value *Addr) { + Entry.setResult(R); + Address = Addr; + } + + const MemDepResult &getResult() const { return Entry.getResult(); } + + /// getAddress - Return the address of this pointer in this block. This can + /// be different than the address queried for the non-local result because + /// of phi translation. This returns null if the address was not available + /// in a block (i.e. because phi translation failed) or if this is a cached + /// result and that address was deleted. + /// + /// The address is always null for a non-local 'call' dependence. + Value *getAddress() const { return Address; } + }; + + /// 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 { + // A map from instructions to their dependency. + typedef DenseMap LocalDepMapType; + LocalDepMapType LocalDeps; + public: - // Special marker indicating that the query has no dependency - // in the specified block. - static Instruction* const NonLocal; + 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; + + /// NonLocalPointerInfo - This record is the information kept for each + /// (value, is load) pair. + struct NonLocalPointerInfo { + /// Pair - The pair of the block and the skip-first-block flag. + BBSkipFirstBlockPair Pair; + /// NonLocalDeps - The results of the query for each relevant block. + NonLocalDepInfo NonLocalDeps; + /// Size - The maximum size of the dereferences of the + /// pointer. May be UnknownSize if the sizes are unknown. + uint64_t Size; + /// TBAATag - The TBAA tag associated with dereferences of the + /// pointer. May be null if there are no tags or conflicting tags. + const MDNode *TBAATag; + + NonLocalPointerInfo() : Size(AliasAnalysis::UnknownSize), TBAATag(0) {} + }; + + /// 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; + - // Special marker indicating that the query has no dependency at all - static Instruction* const None; + /// 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. + typedef DenseMap NonLocalDepMapType; + + NonLocalDepMapType NonLocalDeps; - // Special marker indicating a dirty cache entry - static Instruction* const Dirty; + // A reverse mapping from dependencies to the dependees. This is + // used when removing instructions to keep the cache coherent. + typedef DenseMap > ReverseDepMapType; + ReverseDepMapType ReverseLocalDeps; - static char ID; // Class identification, replacement for typeinfo - MemoryDependenceAnalysis() : FunctionPass((intptr_t)&ID) {} + // A reverse mapping from dependencies to the non-local dependees. + ReverseDepMapType ReverseNonLocalDeps; + + /// Current AA implementation, just a cache. + AliasAnalysis *AA; + DataLayout *TD; + DominatorTree *DT; + OwningPtr PredCache; + public: + 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() { - depGraphLocal.clear(); - depGraphNonLocal.clear(); - reverseDep.clear(); - reverseDepNonLocal.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, starting with start. - Instruction* getDependency(Instruction* query, Instruction* start = 0, - BasicBlock* block = 0); + /// depends. See the class comment for more details. It is illegal to call + /// this on non-memory instructions. + MemDepResult getDependency(Instruction *QueryInst); + + /// 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 + /// within its own block. + /// + /// 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); - /// getNonLocalDependency - Fills the passed-in map with the non-local - /// dependencies of the queries. The map will contain NonLocal for - /// blocks between the query and its dependencies. - void getNonLocalDependency(Instruction* query, - DenseMap& resp); + /// 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(const AliasAnalysis::Location &Loc, + 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* rem); + void removeInstruction(Instruction *InstToRemove); + + /// 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); + + /// invalidateCachedPredecessors - Clear the PredIteratorCache info. + /// This needs to be done when the CFG changes, e.g., due to splitting + /// critical edges. + void invalidateCachedPredecessors(); + + /// getPointerDependencyFrom - Return the instruction on which a memory + /// location depends. If isLoad is true, this routine ignores may-aliases + /// with read-only operations. If isLoad is false, this routine ignores + /// may-aliases with reads from read-only locations. + /// + /// Note that this is an uncached query, and thus may be inefficient. + /// + MemDepResult getPointerDependencyFrom(const AliasAnalysis::Location &Loc, + bool isLoad, + BasicBlock::iterator ScanIt, + BasicBlock *BB); + + + /// getLoadLoadClobberFullWidthSize - This is a little bit of analysis that + /// looks at a memory location for a load (specified by MemLocBase, Offs, + /// and Size) and compares it against a load. If the specified load could + /// be safely widened to a larger integer load that is 1) still efficient, + /// 2) safe for the target, and 3) would provide the specified memory + /// location value, then this function returns the size in bytes of the + /// load width to use. If not, this returns zero. + static unsigned getLoadLoadClobberFullWidthSize(const Value *MemLocBase, + int64_t MemLocOffs, + unsigned MemLocSize, + const LoadInst *LI, + const DataLayout &TD); private: - Instruction* getCallSiteDependency(CallSite C, Instruction* start, - BasicBlock* block); - void nonLocalHelper(Instruction* query, BasicBlock* block, - DenseMap& resp); + MemDepResult getCallSiteDependencyFrom(CallSite C, bool isReadOnlyCall, + BasicBlock::iterator ScanIt, + BasicBlock *BB); + bool getNonLocalPointerDepFromBB(const PHITransAddr &Pointer, + const AliasAnalysis::Location &Loc, + bool isLoad, BasicBlock *BB, + SmallVectorImpl &Result, + DenseMap &Visited, + bool SkipFirstBlock = false); + MemDepResult GetNonLocalInfoForBlock(const AliasAnalysis::Location &Loc, + 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; + }; } // End llvm namespace