Members/tobaru/cbc/CbC_llvm: lib/Analysis/MemoryDependenceAnalysis.cpp comparison

comparison lib/Analysis/MemoryDependenceAnalysis.cpp @ 0:95c75e76d11b

LLVM 3.4

author	Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date	Thu, 12 Dec 2013 13:56:28 +0900
parents
children	54457678186b

comparison

equal deleted inserted replaced

--1:000000000000
+:95c75e76d11b
+//===- MemoryDependenceAnalysis.cpp - Mem Deps Implementation -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements 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.
+//
+//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "memdep"
+#include "llvm/Analysis/MemoryDependenceAnalysis.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/PHITransAddr.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/PredIteratorCache.h"
+using namespace llvm;
+STATISTIC(NumCacheNonLocal, "Number of fully cached non-local responses");
+STATISTIC(NumCacheDirtyNonLocal, "Number of dirty cached non-local responses");
+STATISTIC(NumUncacheNonLocal, "Number of uncached non-local responses");
+STATISTIC(NumCacheNonLocalPtr,
+"Number of fully cached non-local ptr responses");
+STATISTIC(NumCacheDirtyNonLocalPtr,
+"Number of cached, but dirty, non-local ptr responses");
+STATISTIC(NumUncacheNonLocalPtr,
+"Number of uncached non-local ptr responses");
+STATISTIC(NumCacheCompleteNonLocalPtr,
+"Number of block queries that were completely cached");
+// Limit for the number of instructions to scan in a block.
+static const int BlockScanLimit = 100;
+char MemoryDependenceAnalysis::ID = 0;
+// Register this pass...
+INITIALIZE_PASS_BEGIN(MemoryDependenceAnalysis, "memdep",
+"Memory Dependence Analysis", false, true)
+INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
+INITIALIZE_PASS_END(MemoryDependenceAnalysis, "memdep",
+"Memory Dependence Analysis", false, true)
+MemoryDependenceAnalysis::MemoryDependenceAnalysis()
+: FunctionPass(ID), PredCache(0) {
+initializeMemoryDependenceAnalysisPass(*PassRegistry::getPassRegistry());
+}
+MemoryDependenceAnalysis::~MemoryDependenceAnalysis() {
+}
+/// Clean up memory in between runs
+void MemoryDependenceAnalysis::releaseMemory() {
+LocalDeps.clear();
+NonLocalDeps.clear();
+NonLocalPointerDeps.clear();
+ReverseLocalDeps.clear();
+ReverseNonLocalDeps.clear();
+ReverseNonLocalPtrDeps.clear();
+PredCache->clear();
+}
+/// getAnalysisUsage - Does not modify anything.  It uses Alias Analysis.
+///
+void MemoryDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
+AU.setPreservesAll();
+AU.addRequiredTransitive<AliasAnalysis>();
+}
+bool MemoryDependenceAnalysis::runOnFunction(Function &) {
+AA = &getAnalysis<AliasAnalysis>();
+TD = getAnalysisIfAvailable<DataLayout>();
+DT = getAnalysisIfAvailable<DominatorTree>();
+if (!PredCache)
+PredCache.reset(new PredIteratorCache());
+return false;
+}
+/// RemoveFromReverseMap - This is a helper function that removes Val from
+/// 'Inst's set in ReverseMap.  If the set becomes empty, remove Inst's entry.
+template <typename KeyTy>
+static void RemoveFromReverseMap(DenseMap<Instruction*,
+SmallPtrSet<KeyTy, 4> > &ReverseMap,
+Instruction *Inst, KeyTy Val) {
+typename DenseMap<Instruction*, SmallPtrSet<KeyTy, 4> >::iterator
+InstIt = ReverseMap.find(Inst);
+assert(InstIt != ReverseMap.end() && "Reverse map out of sync?");
+bool Found = InstIt->second.erase(Val);
+assert(Found && "Invalid reverse map!"); (void)Found;
+if (InstIt->second.empty())
+ReverseMap.erase(InstIt);
+}
+/// GetLocation - If the given instruction references a specific memory
+/// location, fill in Loc with the details, otherwise set Loc.Ptr to null.
+/// Return a ModRefInfo value describing the general behavior of the
+/// instruction.
+static
+AliasAnalysis::ModRefResult GetLocation(const Instruction *Inst,
+AliasAnalysis::Location &Loc,
+AliasAnalysis *AA) {
+if (const LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+if (LI->isUnordered()) {
+Loc = AA->getLocation(LI);
+return AliasAnalysis::Ref;
+}
+if (LI->getOrdering() == Monotonic) {
+Loc = AA->getLocation(LI);
+return AliasAnalysis::ModRef;
+}
+Loc = AliasAnalysis::Location();
+return AliasAnalysis::ModRef;
+}
+if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+if (SI->isUnordered()) {
+Loc = AA->getLocation(SI);
+return AliasAnalysis::Mod;
+}
+if (SI->getOrdering() == Monotonic) {
+Loc = AA->getLocation(SI);
+return AliasAnalysis::ModRef;
+}
+Loc = AliasAnalysis::Location();
+return AliasAnalysis::ModRef;
+}
+if (const VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
+Loc = AA->getLocation(V);
+return AliasAnalysis::ModRef;
+}
+if (const CallInst *CI = isFreeCall(Inst, AA->getTargetLibraryInfo())) {
+// calls to free() deallocate the entire structure
+Loc = AliasAnalysis::Location(CI->getArgOperand(0));
+return AliasAnalysis::Mod;
+}
+if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst))
+switch (II->getIntrinsicID()) {
+case Intrinsic::lifetime_start:
+case Intrinsic::lifetime_end:
+case Intrinsic::invariant_start:
+Loc = AliasAnalysis::Location(II->getArgOperand(1),
+cast<ConstantInt>(II->getArgOperand(0))
+->getZExtValue(),
+II->getMetadata(LLVMContext::MD_tbaa));
+// These intrinsics don't really modify the memory, but returning Mod
+// will allow them to be handled conservatively.
+return AliasAnalysis::Mod;
+case Intrinsic::invariant_end:
+Loc = AliasAnalysis::Location(II->getArgOperand(2),
+cast<ConstantInt>(II->getArgOperand(1))
+->getZExtValue(),
+II->getMetadata(LLVMContext::MD_tbaa));
+// These intrinsics don't really modify the memory, but returning Mod
+// will allow them to be handled conservatively.
+return AliasAnalysis::Mod;
+default:
+break;
+}
+// Otherwise, just do the coarse-grained thing that always works.
+if (Inst->mayWriteToMemory())
+return AliasAnalysis::ModRef;
+if (Inst->mayReadFromMemory())
+return AliasAnalysis::Ref;
+return AliasAnalysis::NoModRef;
+}
+/// getCallSiteDependencyFrom - Private helper for finding the local
+/// dependencies of a call site.
+MemDepResult MemoryDependenceAnalysis::
+getCallSiteDependencyFrom(CallSite CS, bool isReadOnlyCall,
+BasicBlock::iterator ScanIt, BasicBlock *BB) {
+unsigned Limit = BlockScanLimit;
+// Walk backwards through the block, looking for dependencies
+while (ScanIt != BB->begin()) {
+// Limit the amount of scanning we do so we don't end up with quadratic
+// running time on extreme testcases.
+--Limit;
+if (!Limit)
+return MemDepResult::getUnknown();
+Instruction *Inst = --ScanIt;
+// If this inst is a memory op, get the pointer it accessed
+AliasAnalysis::Location Loc;
+AliasAnalysis::ModRefResult MR = GetLocation(Inst, Loc, AA);
+if (Loc.Ptr) {
+// A simple instruction.
+if (AA->getModRefInfo(CS, Loc) != AliasAnalysis::NoModRef)
+return MemDepResult::getClobber(Inst);
+continue;
+}
+if (CallSite InstCS = cast<Value>(Inst)) {
+// Debug intrinsics don't cause dependences.
+if (isa<DbgInfoIntrinsic>(Inst)) continue;
+// If these two calls do not interfere, look past it.
+switch (AA->getModRefInfo(CS, InstCS)) {
+case AliasAnalysis::NoModRef:
+// If the two calls are the same, return InstCS as a Def, so that
+// CS can be found redundant and eliminated.
+if (isReadOnlyCall && !(MR & AliasAnalysis::Mod) &&
+CS.getInstruction()->isIdenticalToWhenDefined(Inst))
+return MemDepResult::getDef(Inst);
+// Otherwise if the two calls don't interact (e.g. InstCS is readnone)
+// keep scanning.
+continue;
+default:
+return MemDepResult::getClobber(Inst);
+}
+}
+// If we could not obtain a pointer for the instruction and the instruction
+// touches memory then assume that this is a dependency.
+if (MR != AliasAnalysis::NoModRef)
+return MemDepResult::getClobber(Inst);
+}
+// No dependence found.  If this is the entry block of the function, it is
+// unknown, otherwise it is non-local.
+if (BB != &BB->getParent()->getEntryBlock())
+return MemDepResult::getNonLocal();
+return MemDepResult::getNonFuncLocal();
+}
+/// isLoadLoadClobberIfExtendedToFullWidth - Return true if LI is a load that
+/// would fully overlap MemLoc if done as a wider legal integer load.
+///
+/// MemLocBase, MemLocOffset are lazily computed here the first time the
+/// base/offs of memloc is needed.
+static bool
+isLoadLoadClobberIfExtendedToFullWidth(const AliasAnalysis::Location &MemLoc,
+const Value *&MemLocBase,
+int64_t &MemLocOffs,
+const LoadInst *LI,
+const DataLayout *TD) {
+// If we have no target data, we can't do this.
+if (TD == 0) return false;
+// If we haven't already computed the base/offset of MemLoc, do so now.
+if (MemLocBase == 0)
+MemLocBase = GetPointerBaseWithConstantOffset(MemLoc.Ptr, MemLocOffs, TD);
+unsigned Size = MemoryDependenceAnalysis::
+getLoadLoadClobberFullWidthSize(MemLocBase, MemLocOffs, MemLoc.Size,
+LI, *TD);
+return Size != 0;
+}
+/// 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.
+unsigned MemoryDependenceAnalysis::
+getLoadLoadClobberFullWidthSize(const Value *MemLocBase, int64_t MemLocOffs,
+unsigned MemLocSize, const LoadInst *LI,
+const DataLayout &TD) {
+// We can only extend simple integer loads.
+if (!isa<IntegerType>(LI->getType()) || !LI->isSimple()) return 0;
+// Load widening is hostile to ThreadSanitizer: it may cause false positives
+// or make the reports more cryptic (access sizes are wrong).
+if (LI->getParent()->getParent()->getAttributes().
+hasAttribute(AttributeSet::FunctionIndex, Attribute::SanitizeThread))
+return 0;
+// Get the base of this load.
+int64_t LIOffs = 0;
+const Value *LIBase =
+GetPointerBaseWithConstantOffset(LI->getPointerOperand(), LIOffs, &TD);
+// If the two pointers are not based on the same pointer, we can't tell that
+// they are related.
+if (LIBase != MemLocBase) return 0;
+// Okay, the two values are based on the same pointer, but returned as
+// no-alias.  This happens when we have things like two byte loads at "P+1"
+// and "P+3".  Check to see if increasing the size of the "LI" load up to its
+// alignment (or the largest native integer type) will allow us to load all
+// the bits required by MemLoc.
+// If MemLoc is before LI, then no widening of LI will help us out.
+if (MemLocOffs < LIOffs) return 0;
+// Get the alignment of the load in bytes.  We assume that it is safe to load
+// any legal integer up to this size without a problem.  For example, if we're
+// looking at an i8 load on x86-32 that is known 1024 byte aligned, we can
+// widen it up to an i32 load.  If it is known 2-byte aligned, we can widen it
+// to i16.
+unsigned LoadAlign = LI->getAlignment();
+int64_t MemLocEnd = MemLocOffs+MemLocSize;
+// If no amount of rounding up will let MemLoc fit into LI, then bail out.
+if (LIOffs+LoadAlign < MemLocEnd) return 0;
+// This is the size of the load to try.  Start with the next larger power of
+// two.
+unsigned NewLoadByteSize = LI->getType()->getPrimitiveSizeInBits()/8U;
+NewLoadByteSize = NextPowerOf2(NewLoadByteSize);
+while (1) {
+// If this load size is bigger than our known alignment or would not fit
+// into a native integer register, then we fail.
+if (NewLoadByteSize > LoadAlign ||
+!TD.fitsInLegalInteger(NewLoadByteSize*8))
+return 0;
+if (LIOffs+NewLoadByteSize > MemLocEnd &&
+LI->getParent()->getParent()->getAttributes().
+hasAttribute(AttributeSet::FunctionIndex, Attribute::SanitizeAddress))
+// We will be reading past the location accessed by the original program.
+// While this is safe in a regular build, Address Safety analysis tools
+// may start reporting false warnings. So, don't do widening.
+return 0;
+// If a load of this width would include all of MemLoc, then we succeed.
+if (LIOffs+NewLoadByteSize >= MemLocEnd)
+return NewLoadByteSize;
+NewLoadByteSize <<= 1;
+}
+}
+/// 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.  If possible, pass the query
+/// instruction as well; this function may take advantage of the metadata
+/// annotated to the query instruction to refine the result.
+MemDepResult MemoryDependenceAnalysis::
+getPointerDependencyFrom(const AliasAnalysis::Location &MemLoc, bool isLoad,
+BasicBlock::iterator ScanIt, BasicBlock *BB,
+Instruction *QueryInst) {
+const Value *MemLocBase = 0;
+int64_t MemLocOffset = 0;
+unsigned Limit = BlockScanLimit;
+bool isInvariantLoad = false;
+if (isLoad && QueryInst) {
+LoadInst *LI = dyn_cast<LoadInst>(QueryInst);
+if (LI && LI->getMetadata(LLVMContext::MD_invariant_load) != 0)
+isInvariantLoad = true;
+}
+// Walk backwards through the basic block, looking for dependencies.
+while (ScanIt != BB->begin()) {
+Instruction *Inst = --ScanIt;
+if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst))
+// Debug intrinsics don't (and can't) cause dependencies.
+if (isa<DbgInfoIntrinsic>(II)) continue;
+// Limit the amount of scanning we do so we don't end up with quadratic
+// running time on extreme testcases.
+--Limit;
+if (!Limit)
+return MemDepResult::getUnknown();
+if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
+// If we reach a lifetime begin or end marker, then the query ends here
+// because the value is undefined.
+if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
+// FIXME: This only considers queries directly on the invariant-tagged
+// pointer, not on query pointers that are indexed off of them.  It'd
+// be nice to handle that at some point (the right approach is to use
+// GetPointerBaseWithConstantOffset).
+if (AA->isMustAlias(AliasAnalysis::Location(II->getArgOperand(1)),
+MemLoc))
+return MemDepResult::getDef(II);
+continue;
+}
+}
+// Values depend on loads if the pointers are must aliased.  This means that
+// a load depends on another must aliased load from the same value.
+if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+// Atomic loads have complications involved.
+// FIXME: This is overly conservative.
+if (!LI->isUnordered())
+return MemDepResult::getClobber(LI);
+AliasAnalysis::Location LoadLoc = AA->getLocation(LI);
+// If we found a pointer, check if it could be the same as our pointer.
+AliasAnalysis::AliasResult R = AA->alias(LoadLoc, MemLoc);
+if (isLoad) {
+if (R == AliasAnalysis::NoAlias) {
+// If this is an over-aligned integer load (for example,
+// "load i8* %P, align 4") see if it would obviously overlap with the
+// queried location if widened to a larger load (e.g. if the queried
+// location is 1 byte at P+1).  If so, return it as a load/load
+// clobber result, allowing the client to decide to widen the load if
+// it wants to.
+if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType()))
+if (LI->getAlignment()*8 > ITy->getPrimitiveSizeInBits() &&
+isLoadLoadClobberIfExtendedToFullWidth(MemLoc, MemLocBase,
+MemLocOffset, LI, TD))
+return MemDepResult::getClobber(Inst);
+continue;
+}
+// Must aliased loads are defs of each other.
+if (R == AliasAnalysis::MustAlias)
+return MemDepResult::getDef(Inst);
+#if 0 // FIXME: Temporarily disabled. GVN is cleverly rewriting loads
+// in terms of clobbering loads, but since it does this by looking
+// at the clobbering load directly, it doesn't know about any
+// phi translation that may have happened along the way.
+// If we have a partial alias, then return this as a clobber for the
+// client to handle.
+if (R == AliasAnalysis::PartialAlias)
+return MemDepResult::getClobber(Inst);
+#endif
+// Random may-alias loads don't depend on each other without a
+// dependence.
+continue;
+}
+// Stores don't depend on other no-aliased accesses.
+if (R == AliasAnalysis::NoAlias)
+continue;
+// Stores don't alias loads from read-only memory.
+if (AA->pointsToConstantMemory(LoadLoc))
+continue;
+// Stores depend on may/must aliased loads.
+return MemDepResult::getDef(Inst);
+}
+if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+// Atomic stores have complications involved.
+// FIXME: This is overly conservative.
+if (!SI->isUnordered())
+return MemDepResult::getClobber(SI);
+// If alias analysis can tell that this store is guaranteed to not modify
+// the query pointer, ignore it.  Use getModRefInfo to handle cases where
+// the query pointer points to constant memory etc.
+if (AA->getModRefInfo(SI, MemLoc) == AliasAnalysis::NoModRef)
+continue;
+// Ok, this store might clobber the query pointer.  Check to see if it is
+// a must alias: in this case, we want to return this as a def.
+AliasAnalysis::Location StoreLoc = AA->getLocation(SI);
+// If we found a pointer, check if it could be the same as our pointer.
+AliasAnalysis::AliasResult R = AA->alias(StoreLoc, MemLoc);
+if (R == AliasAnalysis::NoAlias)
+continue;
+if (R == AliasAnalysis::MustAlias)
+return MemDepResult::getDef(Inst);
+if (isInvariantLoad)
+continue;
+return MemDepResult::getClobber(Inst);
+}
+// If this is an allocation, and if we know that the accessed pointer is to
+// the allocation, return Def.  This means that there is no dependence and
+// the access can be optimized based on that.  For example, a load could
+// turn into undef.
+// Note: Only determine this to be a malloc if Inst is the malloc call, not
+// a subsequent bitcast of the malloc call result.  There can be stores to
+// the malloced memory between the malloc call and its bitcast uses, and we
+// need to continue scanning until the malloc call.
+const TargetLibraryInfo *TLI = AA->getTargetLibraryInfo();
+if (isa<AllocaInst>(Inst) || isNoAliasFn(Inst, TLI)) {
+const Value *AccessPtr = GetUnderlyingObject(MemLoc.Ptr, TD);
+if (AccessPtr == Inst || AA->isMustAlias(Inst, AccessPtr))
+return MemDepResult::getDef(Inst);
+// Be conservative if the accessed pointer may alias the allocation.
+if (AA->alias(Inst, AccessPtr) != AliasAnalysis::NoAlias)
+return MemDepResult::getClobber(Inst);
+// If the allocation is not aliased and does not read memory (like
+// strdup), it is safe to ignore.
+if (isa<AllocaInst>(Inst) ||
+isMallocLikeFn(Inst, TLI) || isCallocLikeFn(Inst, TLI))
+continue;
+}
+// See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
+AliasAnalysis::ModRefResult MR = AA->getModRefInfo(Inst, MemLoc);
+// If necessary, perform additional analysis.
+if (MR == AliasAnalysis::ModRef)
+MR = AA->callCapturesBefore(Inst, MemLoc, DT);
+switch (MR) {
+case AliasAnalysis::NoModRef:
+// If the call has no effect on the queried pointer, just ignore it.
+continue;
+case AliasAnalysis::Mod:
+return MemDepResult::getClobber(Inst);
+case AliasAnalysis::Ref:
+// If the call is known to never store to the pointer, and if this is a
+// load query, we can safely ignore it (scan past it).
+if (isLoad)
+continue;
+default:
+// Otherwise, there is a potential dependence.  Return a clobber.
+return MemDepResult::getClobber(Inst);
+}
+}
+// No dependence found.  If this is the entry block of the function, it is
+// unknown, otherwise it is non-local.
+if (BB != &BB->getParent()->getEntryBlock())
+return MemDepResult::getNonLocal();
+return MemDepResult::getNonFuncLocal();
+}
+/// getDependency - Return the instruction on which a memory operation
+/// depends.
+MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) {
+Instruction *ScanPos = QueryInst;
+// Check for a cached result
+MemDepResult &LocalCache = LocalDeps[QueryInst];
+// If the cached entry is non-dirty, just return it.  Note that this depends
+// on MemDepResult's default constructing to 'dirty'.
+if (!LocalCache.isDirty())
+return LocalCache;
+// Otherwise, if we have a dirty entry, we know we can start the scan at that
+// instruction, which may save us some work.
+if (Instruction *Inst = LocalCache.getInst()) {
+ScanPos = Inst;
+RemoveFromReverseMap(ReverseLocalDeps, Inst, QueryInst);
+}
+BasicBlock *QueryParent = QueryInst->getParent();
+// Do the scan.
+if (BasicBlock::iterator(QueryInst) == QueryParent->begin()) {
+// No dependence found.  If this is the entry block of the function, it is
+// unknown, otherwise it is non-local.
+if (QueryParent != &QueryParent->getParent()->getEntryBlock())
+LocalCache = MemDepResult::getNonLocal();
+else
+LocalCache = MemDepResult::getNonFuncLocal();
+} else {
+AliasAnalysis::Location MemLoc;
+AliasAnalysis::ModRefResult MR = GetLocation(QueryInst, MemLoc, AA);
+if (MemLoc.Ptr) {
+// If we can do a pointer scan, make it happen.
+bool isLoad = !(MR & AliasAnalysis::Mod);
+if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(QueryInst))
+isLoad |= II->getIntrinsicID() == Intrinsic::lifetime_start;
+LocalCache = getPointerDependencyFrom(MemLoc, isLoad, ScanPos,
+QueryParent, QueryInst);
+} else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
+CallSite QueryCS(QueryInst);
+bool isReadOnly = AA->onlyReadsMemory(QueryCS);
+LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos,
+QueryParent);
+} else
+// Non-memory instruction.
+LocalCache = MemDepResult::getUnknown();
+}
+// Remember the result!
+if (Instruction *I = LocalCache.getInst())
+ReverseLocalDeps[I].insert(QueryInst);
+return LocalCache;
+}
+#ifndef NDEBUG
+/// AssertSorted - This method is used when -debug is specified to verify that
+/// cache arrays are properly kept sorted.
+static void AssertSorted(MemoryDependenceAnalysis::NonLocalDepInfo &Cache,
+int Count = -1) {
+if (Count == -1) Count = Cache.size();
+if (Count == 0) return;
+for (unsigned i = 1; i != unsigned(Count); ++i)
+assert(!(Cache[i] < Cache[i-1]) && "Cache isn't sorted!");
+}
+#endif
+/// 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 MemoryDependenceAnalysis::NonLocalDepInfo &
+MemoryDependenceAnalysis::getNonLocalCallDependency(CallSite QueryCS) {
+assert(getDependency(QueryCS.getInstruction()).isNonLocal() &&
+"getNonLocalCallDependency should only be used on calls with non-local deps!");
+PerInstNLInfo &CacheP = NonLocalDeps[QueryCS.getInstruction()];
+NonLocalDepInfo &Cache = CacheP.first;
+/// DirtyBlocks - This is the set of blocks that need to be recomputed.  In
+/// the cached case, this can happen due to instructions being deleted etc. In
+/// the uncached case, this starts out as the set of predecessors we care
+/// about.
+SmallVector<BasicBlock*, 32> DirtyBlocks;
+if (!Cache.empty()) {
+// Okay, we have a cache entry.  If we know it is not dirty, just return it
+// with no computation.
+if (!CacheP.second) {
+++NumCacheNonLocal;
+return Cache;
+}
+// If we already have a partially computed set of results, scan them to
+// determine what is dirty, seeding our initial DirtyBlocks worklist.
+for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end();
+I != E; ++I)
+if (I->getResult().isDirty())
+DirtyBlocks.push_back(I->getBB());
+// Sort the cache so that we can do fast binary search lookups below.
+std::sort(Cache.begin(), Cache.end());
+++NumCacheDirtyNonLocal;
+//cerr << "CACHED CASE: " << DirtyBlocks.size() << " dirty: "
+//     << Cache.size() << " cached: " << *QueryInst;
+} else {
+// Seed DirtyBlocks with each of the preds of QueryInst's block.
+BasicBlock *QueryBB = QueryCS.getInstruction()->getParent();
+for (BasicBlock **PI = PredCache->GetPreds(QueryBB); *PI; ++PI)
+DirtyBlocks.push_back(*PI);
+++NumUncacheNonLocal;
+}
+// isReadonlyCall - If this is a read-only call, we can be more aggressive.
+bool isReadonlyCall = AA->onlyReadsMemory(QueryCS);
+SmallPtrSet<BasicBlock*, 64> Visited;
+unsigned NumSortedEntries = Cache.size();
+DEBUG(AssertSorted(Cache));
+// Iterate while we still have blocks to update.
+while (!DirtyBlocks.empty()) {
+BasicBlock *DirtyBB = DirtyBlocks.back();
+DirtyBlocks.pop_back();
+// Already processed this block?
+if (!Visited.insert(DirtyBB))
+continue;
+// Do a binary search to see if we already have an entry for this block in
+// the cache set.  If so, find it.
+DEBUG(AssertSorted(Cache, NumSortedEntries));
+NonLocalDepInfo::iterator Entry =
+std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries,
+NonLocalDepEntry(DirtyBB));
+if (Entry != Cache.begin() && prior(Entry)->getBB() == DirtyBB)
+--Entry;
+NonLocalDepEntry *ExistingResult = 0;
+if (Entry != Cache.begin()+NumSortedEntries &&
+Entry->getBB() == DirtyBB) {
+// If we already have an entry, and if it isn't already dirty, the block
+// is done.
+if (!Entry->getResult().isDirty())
+continue;
+// Otherwise, remember this slot so we can update the value.
+ExistingResult = &*Entry;
+}
+// If the dirty entry has a pointer, start scanning from it so we don't have
+// to rescan the entire block.
+BasicBlock::iterator ScanPos = DirtyBB->end();
+if (ExistingResult) {
+if (Instruction *Inst = ExistingResult->getResult().getInst()) {
+ScanPos = Inst;
+// We're removing QueryInst's use of Inst.
+RemoveFromReverseMap(ReverseNonLocalDeps, Inst,
+QueryCS.getInstruction());
+}
+}
+// Find out if this block has a local dependency for QueryInst.
+MemDepResult Dep;
+if (ScanPos != DirtyBB->begin()) {
+Dep = getCallSiteDependencyFrom(QueryCS, isReadonlyCall,ScanPos, DirtyBB);
+} else if (DirtyBB != &DirtyBB->getParent()->getEntryBlock()) {
+// No dependence found.  If this is the entry block of the function, it is
+// a clobber, otherwise it is unknown.
+Dep = MemDepResult::getNonLocal();
+} else {
+Dep = MemDepResult::getNonFuncLocal();
+}
+// If we had a dirty entry for the block, update it.  Otherwise, just add
+// a new entry.
+if (ExistingResult)
+ExistingResult->setResult(Dep);
+else
+Cache.push_back(NonLocalDepEntry(DirtyBB, Dep));
+// If the block has a dependency (i.e. it isn't completely transparent to
+// the value), remember the association!
+if (!Dep.isNonLocal()) {
+// Keep the ReverseNonLocalDeps map up to date so we can efficiently
+// update this when we remove instructions.
+if (Instruction *Inst = Dep.getInst())
+ReverseNonLocalDeps[Inst].insert(QueryCS.getInstruction());
+} else {
+// If the block *is* completely transparent to the load, we need to check
+// the predecessors of this block.  Add them to our worklist.
+for (BasicBlock **PI = PredCache->GetPreds(DirtyBB); *PI; ++PI)
+DirtyBlocks.push_back(*PI);
+}
+}
+return Cache;
+}
+/// 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 its
+/// own block.
+///
+void MemoryDependenceAnalysis::
+getNonLocalPointerDependency(const AliasAnalysis::Location &Loc, bool isLoad,
+BasicBlock *FromBB,
+SmallVectorImpl<NonLocalDepResult> &Result) {
+assert(Loc.Ptr->getType()->isPointerTy() &&
+"Can't get pointer deps of a non-pointer!");
+Result.clear();
+PHITransAddr Address(const_cast<Value *>(Loc.Ptr), TD);
+// This is the set of blocks we've inspected, and the pointer we consider in
+// each block.  Because of critical edges, we currently bail out if querying
+// a block with multiple different pointers.  This can happen during PHI
+// translation.
+DenseMap<BasicBlock*, Value*> Visited;
+if (!getNonLocalPointerDepFromBB(Address, Loc, isLoad, FromBB,
+Result, Visited, true))
+return;
+Result.clear();
+Result.push_back(NonLocalDepResult(FromBB,
+MemDepResult::getUnknown(),
+const_cast<Value *>(Loc.Ptr)));
+}
+/// GetNonLocalInfoForBlock - Compute the memdep value for BB with
+/// Pointer/PointeeSize using either cached information in Cache or by doing a
+/// lookup (which may use dirty cache info if available).  If we do a lookup,
+/// add the result to the cache.
+MemDepResult MemoryDependenceAnalysis::
+GetNonLocalInfoForBlock(const AliasAnalysis::Location &Loc,
+bool isLoad, BasicBlock *BB,
+NonLocalDepInfo *Cache, unsigned NumSortedEntries) {
+// Do a binary search to see if we already have an entry for this block in
+// the cache set.  If so, find it.
+NonLocalDepInfo::iterator Entry =
+std::upper_bound(Cache->begin(), Cache->begin()+NumSortedEntries,
+NonLocalDepEntry(BB));
+if (Entry != Cache->begin() && (Entry-1)->getBB() == BB)
+--Entry;
+NonLocalDepEntry *ExistingResult = 0;
+if (Entry != Cache->begin()+NumSortedEntries && Entry->getBB() == BB)
+ExistingResult = &*Entry;
+// If we have a cached entry, and it is non-dirty, use it as the value for
+// this dependency.
+if (ExistingResult && !ExistingResult->getResult().isDirty()) {
+++NumCacheNonLocalPtr;
+return ExistingResult->getResult();
+}
+// Otherwise, we have to scan for the value.  If we have a dirty cache
+// entry, start scanning from its position, otherwise we scan from the end
+// of the block.
+BasicBlock::iterator ScanPos = BB->end();
+if (ExistingResult && ExistingResult->getResult().getInst()) {
+assert(ExistingResult->getResult().getInst()->getParent() == BB &&
+"Instruction invalidated?");
+++NumCacheDirtyNonLocalPtr;
+ScanPos = ExistingResult->getResult().getInst();
+// Eliminating the dirty entry from 'Cache', so update the reverse info.
+ValueIsLoadPair CacheKey(Loc.Ptr, isLoad);
+RemoveFromReverseMap(ReverseNonLocalPtrDeps, ScanPos, CacheKey);
+} else {
+++NumUncacheNonLocalPtr;
+}
+// Scan the block for the dependency.
+MemDepResult Dep = getPointerDependencyFrom(Loc, isLoad, ScanPos, BB);
+// If we had a dirty entry for the block, update it.  Otherwise, just add
+// a new entry.
+if (ExistingResult)
+ExistingResult->setResult(Dep);
+else
+Cache->push_back(NonLocalDepEntry(BB, Dep));
+// If the block has a dependency (i.e. it isn't completely transparent to
+// the value), remember the reverse association because we just added it
+// to Cache!
+if (!Dep.isDef() && !Dep.isClobber())
+return Dep;
+// Keep the ReverseNonLocalPtrDeps map up to date so we can efficiently
+// update MemDep when we remove instructions.
+Instruction *Inst = Dep.getInst();
+assert(Inst && "Didn't depend on anything?");
+ValueIsLoadPair CacheKey(Loc.Ptr, isLoad);
+ReverseNonLocalPtrDeps[Inst].insert(CacheKey);
+return Dep;
+}
+/// SortNonLocalDepInfoCache - Sort the a NonLocalDepInfo cache, given a certain
+/// number of elements in the array that are already properly ordered.  This is
+/// optimized for the case when only a few entries are added.
+static void
+SortNonLocalDepInfoCache(MemoryDependenceAnalysis::NonLocalDepInfo &Cache,
+unsigned NumSortedEntries) {
+switch (Cache.size() - NumSortedEntries) {
+case 0:
+// done, no new entries.
+break;
+case 2: {
+// Two new entries, insert the last one into place.
+NonLocalDepEntry Val = Cache.back();
+Cache.pop_back();
+MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry =
+std::upper_bound(Cache.begin(), Cache.end()-1, Val);
+Cache.insert(Entry, Val);
+// FALL THROUGH.
+}
+case 1:
+// One new entry, Just insert the new value at the appropriate position.
+if (Cache.size() != 1) {
+NonLocalDepEntry Val = Cache.back();
+Cache.pop_back();
+MemoryDependenceAnalysis::NonLocalDepInfo::iterator Entry =
+std::upper_bound(Cache.begin(), Cache.end(), Val);
+Cache.insert(Entry, Val);
+}
+break;
+default:
+// Added many values, do a full scale sort.
+std::sort(Cache.begin(), Cache.end());
+break;
+}
+}
+/// getNonLocalPointerDepFromBB - Perform a dependency query based on
+/// pointer/pointeesize starting at the end of StartBB.  Add any clobber/def
+/// results to the results vector and keep track of which blocks are visited in
+/// 'Visited'.
+///
+/// This has special behavior for the first block queries (when SkipFirstBlock
+/// is true).  In this special case, it ignores the contents of the specified
+/// block and starts returning dependence info for its predecessors.
+///
+/// This function returns false on success, or true to indicate that it could
+/// not compute dependence information for some reason.  This should be treated
+/// as a clobber dependence on the first instruction in the predecessor block.
+bool MemoryDependenceAnalysis::
+getNonLocalPointerDepFromBB(const PHITransAddr &Pointer,
+const AliasAnalysis::Location &Loc,
+bool isLoad, BasicBlock *StartBB,
+SmallVectorImpl<NonLocalDepResult> &Result,
+DenseMap<BasicBlock*, Value*> &Visited,
+bool SkipFirstBlock) {
+// Look up the cached info for Pointer.
+ValueIsLoadPair CacheKey(Pointer.getAddr(), isLoad);
+// Set up a temporary NLPI value. If the map doesn't yet have an entry for
+// CacheKey, this value will be inserted as the associated value. Otherwise,
+// it'll be ignored, and we'll have to check to see if the cached size and
+// tbaa tag are consistent with the current query.
+NonLocalPointerInfo InitialNLPI;
+InitialNLPI.Size = Loc.Size;
+InitialNLPI.TBAATag = Loc.TBAATag;
+// Get the NLPI for CacheKey, inserting one into the map if it doesn't
+// already have one.
+std::pair<CachedNonLocalPointerInfo::iterator, bool> Pair =
+NonLocalPointerDeps.insert(std::make_pair(CacheKey, InitialNLPI));
+NonLocalPointerInfo *CacheInfo = &Pair.first->second;
+// If we already have a cache entry for this CacheKey, we may need to do some
+// work to reconcile the cache entry and the current query.
+if (!Pair.second) {
+if (CacheInfo->Size < Loc.Size) {
+// The query's Size is greater than the cached one. Throw out the
+// cached data and proceed with the query at the greater size.
+CacheInfo->Pair = BBSkipFirstBlockPair();
+CacheInfo->Size = Loc.Size;
+for (NonLocalDepInfo::iterator DI = CacheInfo->NonLocalDeps.begin(),
+DE = CacheInfo->NonLocalDeps.end(); DI != DE; ++DI)
+if (Instruction *Inst = DI->getResult().getInst())
+RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey);
+CacheInfo->NonLocalDeps.clear();
+} else if (CacheInfo->Size > Loc.Size) {
+// This query's Size is less than the cached one. Conservatively restart
+// the query using the greater size.
+return getNonLocalPointerDepFromBB(Pointer,
+Loc.getWithNewSize(CacheInfo->Size),
+isLoad, StartBB, Result, Visited,
+SkipFirstBlock);
+}
+// If the query's TBAATag is inconsistent with the cached one,
+// conservatively throw out the cached data and restart the query with
+// no tag if needed.
+if (CacheInfo->TBAATag != Loc.TBAATag) {
+if (CacheInfo->TBAATag) {
+CacheInfo->Pair = BBSkipFirstBlockPair();
+CacheInfo->TBAATag = 0;
+for (NonLocalDepInfo::iterator DI = CacheInfo->NonLocalDeps.begin(),
+DE = CacheInfo->NonLocalDeps.end(); DI != DE; ++DI)
+if (Instruction *Inst = DI->getResult().getInst())
+RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey);
+CacheInfo->NonLocalDeps.clear();
+}
+if (Loc.TBAATag)
+return getNonLocalPointerDepFromBB(Pointer, Loc.getWithoutTBAATag(),
+isLoad, StartBB, Result, Visited,
+SkipFirstBlock);
+}
+}
+NonLocalDepInfo *Cache = &CacheInfo->NonLocalDeps;
+// If we have valid cached information for exactly the block we are
+// investigating, just return it with no recomputation.
+if (CacheInfo->Pair == BBSkipFirstBlockPair(StartBB, SkipFirstBlock)) {
+// We have a fully cached result for this query then we can just return the
+// cached results and populate the visited set.  However, we have to verify
+// that we don't already have conflicting results for these blocks.  Check
+// to ensure that if a block in the results set is in the visited set that
+// it was for the same pointer query.
+if (!Visited.empty()) {
+for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
+I != E; ++I) {
+DenseMap<BasicBlock*, Value*>::iterator VI = Visited.find(I->getBB());
+if (VI == Visited.end() || VI->second == Pointer.getAddr())
+continue;
+// We have a pointer mismatch in a block.  Just return clobber, saying
+// that something was clobbered in this result.  We could also do a
+// non-fully cached query, but there is little point in doing this.
+return true;
+}
+}
+Value *Addr = Pointer.getAddr();
+for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
+I != E; ++I) {
+Visited.insert(std::make_pair(I->getBB(), Addr));
+if (I->getResult().isNonLocal()) {
+continue;
+}
+if (!DT) {
+Result.push_back(NonLocalDepResult(I->getBB(),
+MemDepResult::getUnknown(),
+Addr));
+} else if (DT->isReachableFromEntry(I->getBB())) {
+Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(), Addr));
+}
+}
+++NumCacheCompleteNonLocalPtr;
+return false;
+}
+// Otherwise, either this is a new block, a block with an invalid cache
+// pointer or one that we're about to invalidate by putting more info into it
+// than its valid cache info.  If empty, the result will be valid cache info,
+// otherwise it isn't.
+if (Cache->empty())
+CacheInfo->Pair = BBSkipFirstBlockPair(StartBB, SkipFirstBlock);
+else
+CacheInfo->Pair = BBSkipFirstBlockPair();
+SmallVector<BasicBlock*, 32> Worklist;
+Worklist.push_back(StartBB);
+// PredList used inside loop.
+SmallVector<std::pair<BasicBlock*, PHITransAddr>, 16> PredList;
+// Keep track of the entries that we know are sorted.  Previously cached
+// entries will all be sorted.  The entries we add we only sort on demand (we
+// don't insert every element into its sorted position).  We know that we
+// won't get any reuse from currently inserted values, because we don't
+// revisit blocks after we insert info for them.
+unsigned NumSortedEntries = Cache->size();
+DEBUG(AssertSorted(*Cache));
+while (!Worklist.empty()) {
+BasicBlock *BB = Worklist.pop_back_val();
+// Skip the first block if we have it.
+if (!SkipFirstBlock) {
+// Analyze the dependency of *Pointer in FromBB.  See if we already have
+// been here.
+assert(Visited.count(BB) && "Should check 'visited' before adding to WL");
+// Get the dependency info for Pointer in BB.  If we have cached
+// information, we will use it, otherwise we compute it.
+DEBUG(AssertSorted(*Cache, NumSortedEntries));
+MemDepResult Dep = GetNonLocalInfoForBlock(Loc, isLoad, BB, Cache,
+NumSortedEntries);
+// If we got a Def or Clobber, add this to the list of results.
+if (!Dep.isNonLocal()) {
+if (!DT) {
+Result.push_back(NonLocalDepResult(BB,
+MemDepResult::getUnknown(),
+Pointer.getAddr()));
+continue;
+} else if (DT->isReachableFromEntry(BB)) {
+Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr()));
+continue;
+}
+}
+}
+// If 'Pointer' is an instruction defined in this block, then we need to do
+// phi translation to change it into a value live in the predecessor block.
+// If not, we just add the predecessors to the worklist and scan them with
+// the same Pointer.
+if (!Pointer.NeedsPHITranslationFromBlock(BB)) {
+SkipFirstBlock = false;
+SmallVector<BasicBlock*, 16> NewBlocks;
+for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
+// Verify that we haven't looked at this block yet.
+std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
+InsertRes = Visited.insert(std::make_pair(*PI, Pointer.getAddr()));
+if (InsertRes.second) {
+// First time we've looked at *PI.
+NewBlocks.push_back(*PI);
+continue;
+}
+// If we have seen this block before, but it was with a different
+// pointer then we have a phi translation failure and we have to treat
+// this as a clobber.
+if (InsertRes.first->second != Pointer.getAddr()) {
+// Make sure to clean up the Visited map before continuing on to
+// PredTranslationFailure.
+for (unsigned i = 0; i < NewBlocks.size(); i++)
+Visited.erase(NewBlocks[i]);
+goto PredTranslationFailure;
+}
+}
+Worklist.append(NewBlocks.begin(), NewBlocks.end());
+continue;
+}
+// We do need to do phi translation, if we know ahead of time we can't phi
+// translate this value, don't even try.
+if (!Pointer.IsPotentiallyPHITranslatable())
+goto PredTranslationFailure;
+// We may have added values to the cache list before this PHI translation.
+// If so, we haven't done anything to ensure that the cache remains sorted.
+// Sort it now (if needed) so that recursive invocations of
+// getNonLocalPointerDepFromBB and other routines that could reuse the cache
+// value will only see properly sorted cache arrays.
+if (Cache && NumSortedEntries != Cache->size()) {
+SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
+NumSortedEntries = Cache->size();
+}
+Cache = 0;
+PredList.clear();
+for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
+BasicBlock *Pred = *PI;
+PredList.push_back(std::make_pair(Pred, Pointer));
+// Get the PHI translated pointer in this predecessor.  This can fail if
+// not translatable, in which case the getAddr() returns null.
+PHITransAddr &PredPointer = PredList.back().second;
+PredPointer.PHITranslateValue(BB, Pred, 0);
+Value *PredPtrVal = PredPointer.getAddr();
+// Check to see if we have already visited this pred block with another
+// pointer.  If so, we can't do this lookup.  This failure can occur
+// with PHI translation when a critical edge exists and the PHI node in
+// the successor translates to a pointer value different than the
+// pointer the block was first analyzed with.
+std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
+InsertRes = Visited.insert(std::make_pair(Pred, PredPtrVal));
+if (!InsertRes.second) {
+// We found the pred; take it off the list of preds to visit.
+PredList.pop_back();
+// If the predecessor was visited with PredPtr, then we already did
+// the analysis and can ignore it.
+if (InsertRes.first->second == PredPtrVal)
+continue;
+// Otherwise, the block was previously analyzed with a different
+// pointer.  We can't represent the result of this case, so we just
+// treat this as a phi translation failure.
+// Make sure to clean up the Visited map before continuing on to
+// PredTranslationFailure.
+for (unsigned i = 0, n = PredList.size(); i < n; ++i)
+Visited.erase(PredList[i].first);
+goto PredTranslationFailure;
+}
+}
+// Actually process results here; this need to be a separate loop to avoid
+// calling getNonLocalPointerDepFromBB for blocks we don't want to return
+// any results for.  (getNonLocalPointerDepFromBB will modify our
+// datastructures in ways the code after the PredTranslationFailure label
+// doesn't expect.)
+for (unsigned i = 0, n = PredList.size(); i < n; ++i) {
+BasicBlock *Pred = PredList[i].first;
+PHITransAddr &PredPointer = PredList[i].second;
+Value *PredPtrVal = PredPointer.getAddr();
+bool CanTranslate = true;
+// If PHI translation was unable to find an available pointer in this
+// predecessor, then we have to assume that the pointer is clobbered in
+// that predecessor.  We can still do PRE of the load, which would insert
+// a computation of the pointer in this predecessor.
+if (PredPtrVal == 0)
+CanTranslate = false;
+// FIXME: it is entirely possible that PHI translating will end up with
+// the same value.  Consider PHI translating something like:
+// X = phi [x, bb1], [y, bb2].  PHI translating for bb1 doesn't *need*
+// to recurse here, pedantically speaking.
+// If getNonLocalPointerDepFromBB fails here, that means the cached
+// result conflicted with the Visited list; we have to conservatively
+// assume it is unknown, but this also does not block PRE of the load.
+if (!CanTranslate ||
+getNonLocalPointerDepFromBB(PredPointer,
+Loc.getWithNewPtr(PredPtrVal),
+isLoad, Pred,
+Result, Visited)) {
+// Add the entry to the Result list.
+NonLocalDepResult Entry(Pred, MemDepResult::getUnknown(), PredPtrVal);
+Result.push_back(Entry);
+// Since we had a phi translation failure, the cache for CacheKey won't
+// include all of the entries that we need to immediately satisfy future
+// queries.  Mark this in NonLocalPointerDeps by setting the
+// BBSkipFirstBlockPair pointer to null.  This requires reuse of the
+// cached value to do more work but not miss the phi trans failure.
+NonLocalPointerInfo &NLPI = NonLocalPointerDeps[CacheKey];
+NLPI.Pair = BBSkipFirstBlockPair();
+continue;
+}
+}
+// Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
+CacheInfo = &NonLocalPointerDeps[CacheKey];
+Cache = &CacheInfo->NonLocalDeps;
+NumSortedEntries = Cache->size();
+// Since we did phi translation, the "Cache" set won't contain all of the
+// results for the query.  This is ok (we can still use it to accelerate
+// specific block queries) but we can't do the fastpath "return all
+// results from the set"  Clear out the indicator for this.
+CacheInfo->Pair = BBSkipFirstBlockPair();
+SkipFirstBlock = false;
+continue;
+PredTranslationFailure:
+// The following code is "failure"; we can't produce a sane translation
+// for the given block.  It assumes that we haven't modified any of
+// our datastructures while processing the current block.
+if (Cache == 0) {
+// Refresh the CacheInfo/Cache pointer if it got invalidated.
+CacheInfo = &NonLocalPointerDeps[CacheKey];
+Cache = &CacheInfo->NonLocalDeps;
+NumSortedEntries = Cache->size();
+}
+// Since we failed phi translation, the "Cache" set won't contain all of the
+// results for the query.  This is ok (we can still use it to accelerate
+// specific block queries) but we can't do the fastpath "return all
+// results from the set".  Clear out the indicator for this.
+CacheInfo->Pair = BBSkipFirstBlockPair();
+// If *nothing* works, mark the pointer as unknown.
+//
+// If this is the magic first block, return this as a clobber of the whole
+// incoming value.  Since we can't phi translate to one of the predecessors,
+// we have to bail out.
+if (SkipFirstBlock)
+return true;
+for (NonLocalDepInfo::reverse_iterator I = Cache->rbegin(); ; ++I) {
+assert(I != Cache->rend() && "Didn't find current block??");
+if (I->getBB() != BB)
+continue;
+assert(I->getResult().isNonLocal() &&
+"Should only be here with transparent block");
+I->setResult(MemDepResult::getUnknown());
+Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(),
+Pointer.getAddr()));
+break;
+}
+}
+// Okay, we're done now.  If we added new values to the cache, re-sort it.
+SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
+DEBUG(AssertSorted(*Cache));
+return false;
+}
+/// RemoveCachedNonLocalPointerDependencies - If P exists in
+/// CachedNonLocalPointerInfo, remove it.
+void MemoryDependenceAnalysis::
+RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair P) {
+CachedNonLocalPointerInfo::iterator It =
+NonLocalPointerDeps.find(P);
+if (It == NonLocalPointerDeps.end()) return;
+// Remove all of the entries in the BB->val map.  This involves removing
+// instructions from the reverse map.
+NonLocalDepInfo &PInfo = It->second.NonLocalDeps;
+for (unsigned i = 0, e = PInfo.size(); i != e; ++i) {
+Instruction *Target = PInfo[i].getResult().getInst();
+if (Target == 0) continue;  // Ignore non-local dep results.
+assert(Target->getParent() == PInfo[i].getBB());
+// Eliminating the dirty entry from 'Cache', so update the reverse info.
+RemoveFromReverseMap(ReverseNonLocalPtrDeps, Target, P);
+}
+// Remove P from NonLocalPointerDeps (which deletes NonLocalDepInfo).
+NonLocalPointerDeps.erase(It);
+}
+/// 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 MemoryDependenceAnalysis::invalidateCachedPointerInfo(Value *Ptr) {
+// If Ptr isn't really a pointer, just ignore it.
+if (!Ptr->getType()->isPointerTy()) return;
+// Flush store info for the pointer.
+RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, false));
+// Flush load info for the pointer.
+RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, true));
+}
+/// invalidateCachedPredecessors - Clear the PredIteratorCache info.
+/// This needs to be done when the CFG changes, e.g., due to splitting
+/// critical edges.
+void MemoryDependenceAnalysis::invalidateCachedPredecessors() {
+PredCache->clear();
+}
+/// removeInstruction - Remove an instruction from the dependence analysis,
+/// updating the dependence of instructions that previously depended on it.
+/// This method attempts to keep the cache coherent using the reverse map.
+void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
+// Walk through the Non-local dependencies, removing this one as the value
+// for any cached queries.
+NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst);
+if (NLDI != NonLocalDeps.end()) {
+NonLocalDepInfo &BlockMap = NLDI->second.first;
+for (NonLocalDepInfo::iterator DI = BlockMap.begin(), DE = BlockMap.end();
+DI != DE; ++DI)
+if (Instruction *Inst = DI->getResult().getInst())
+RemoveFromReverseMap(ReverseNonLocalDeps, Inst, RemInst);
+NonLocalDeps.erase(NLDI);
+}
+// If we have a cached local dependence query for this instruction, remove it.
+//
+LocalDepMapType::iterator LocalDepEntry = LocalDeps.find(RemInst);
+if (LocalDepEntry != LocalDeps.end()) {
+// Remove us from DepInst's reverse set now that the local dep info is gone.
+if (Instruction *Inst = LocalDepEntry->second.getInst())
+RemoveFromReverseMap(ReverseLocalDeps, Inst, RemInst);
+// Remove this local dependency info.
+LocalDeps.erase(LocalDepEntry);
+}
+// If we have any cached pointer dependencies on this instruction, remove
+// them.  If the instruction has non-pointer type, then it can't be a pointer
+// base.
+// Remove it from both the load info and the store info.  The instruction
+// can't be in either of these maps if it is non-pointer.
+if (RemInst->getType()->isPointerTy()) {
+RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, false));
+RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, true));
+}
+// Loop over all of the things that depend on the instruction we're removing.
+//
+SmallVector<std::pair<Instruction*, Instruction*>, 8> ReverseDepsToAdd;
+// If we find RemInst as a clobber or Def in any of the maps for other values,
+// we need to replace its entry with a dirty version of the instruction after
+// it.  If RemInst is a terminator, we use a null dirty value.
+//
+// Using a dirty version of the instruction after RemInst saves having to scan
+// the entire block to get to this point.
+MemDepResult NewDirtyVal;
+if (!RemInst->isTerminator())
+NewDirtyVal = MemDepResult::getDirty(++BasicBlock::iterator(RemInst));
+ReverseDepMapType::iterator ReverseDepIt = ReverseLocalDeps.find(RemInst);
+if (ReverseDepIt != ReverseLocalDeps.end()) {
+SmallPtrSet<Instruction*, 4> &ReverseDeps = ReverseDepIt->second;
+// RemInst can't be the terminator if it has local stuff depending on it.
+assert(!ReverseDeps.empty() && !isa<TerminatorInst>(RemInst) &&
+"Nothing can locally depend on a terminator");
+for (SmallPtrSet<Instruction*, 4>::iterator I = ReverseDeps.begin(),
+E = ReverseDeps.end(); I != E; ++I) {
+Instruction *InstDependingOnRemInst = *I;
+assert(InstDependingOnRemInst != RemInst &&
+"Already removed our local dep info");
+LocalDeps[InstDependingOnRemInst] = NewDirtyVal;
+// Make sure to remember that new things depend on NewDepInst.
+assert(NewDirtyVal.getInst() && "There is no way something else can have "
+"a local dep on this if it is a terminator!");
+ReverseDepsToAdd.push_back(std::make_pair(NewDirtyVal.getInst(),
+InstDependingOnRemInst));
+}
+ReverseLocalDeps.erase(ReverseDepIt);
+// Add new reverse deps after scanning the set, to avoid invalidating the
+// 'ReverseDeps' reference.
+while (!ReverseDepsToAdd.empty()) {
+ReverseLocalDeps[ReverseDepsToAdd.back().first]
+.insert(ReverseDepsToAdd.back().second);
+ReverseDepsToAdd.pop_back();
+}
+}
+ReverseDepIt = ReverseNonLocalDeps.find(RemInst);
+if (ReverseDepIt != ReverseNonLocalDeps.end()) {
+SmallPtrSet<Instruction*, 4> &Set = ReverseDepIt->second;
+for (SmallPtrSet<Instruction*, 4>::iterator I = Set.begin(), E = Set.end();
+I != E; ++I) {
+assert(*I != RemInst && "Already removed NonLocalDep info for RemInst");
+PerInstNLInfo &INLD = NonLocalDeps[*I];
+// The information is now dirty!
+INLD.second = true;
+for (NonLocalDepInfo::iterator DI = INLD.first.begin(),
+DE = INLD.first.end(); DI != DE; ++DI) {
+if (DI->getResult().getInst() != RemInst) continue;
+// Convert to a dirty entry for the subsequent instruction.
+DI->setResult(NewDirtyVal);
+if (Instruction *NextI = NewDirtyVal.getInst())
+ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
+}
+}
+ReverseNonLocalDeps.erase(ReverseDepIt);
+// Add new reverse deps after scanning the set, to avoid invalidating 'Set'
+while (!ReverseDepsToAdd.empty()) {
+ReverseNonLocalDeps[ReverseDepsToAdd.back().first]
+.insert(ReverseDepsToAdd.back().second);
+ReverseDepsToAdd.pop_back();
+}
+}
+// If the instruction is in ReverseNonLocalPtrDeps then it appears as a
+// value in the NonLocalPointerDeps info.
+ReverseNonLocalPtrDepTy::iterator ReversePtrDepIt =
+ReverseNonLocalPtrDeps.find(RemInst);
+if (ReversePtrDepIt != ReverseNonLocalPtrDeps.end()) {
+SmallPtrSet<ValueIsLoadPair, 4> &Set = ReversePtrDepIt->second;
+SmallVector<std::pair<Instruction*, ValueIsLoadPair>,8> ReversePtrDepsToAdd;
+for (SmallPtrSet<ValueIsLoadPair, 4>::iterator I = Set.begin(),
+E = Set.end(); I != E; ++I) {
+ValueIsLoadPair P = *I;
+assert(P.getPointer() != RemInst &&
+"Already removed NonLocalPointerDeps info for RemInst");
+NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P].NonLocalDeps;
+// The cache is not valid for any specific block anymore.
+NonLocalPointerDeps[P].Pair = BBSkipFirstBlockPair();
+// Update any entries for RemInst to use the instruction after it.
+for (NonLocalDepInfo::iterator DI = NLPDI.begin(), DE = NLPDI.end();
+DI != DE; ++DI) {
+if (DI->getResult().getInst() != RemInst) continue;
+// Convert to a dirty entry for the subsequent instruction.
+DI->setResult(NewDirtyVal);
+if (Instruction *NewDirtyInst = NewDirtyVal.getInst())
+ReversePtrDepsToAdd.push_back(std::make_pair(NewDirtyInst, P));
+}
+// Re-sort the NonLocalDepInfo.  Changing the dirty entry to its
+// subsequent value may invalidate the sortedness.
+std::sort(NLPDI.begin(), NLPDI.end());
+}
+ReverseNonLocalPtrDeps.erase(ReversePtrDepIt);
+while (!ReversePtrDepsToAdd.empty()) {
+ReverseNonLocalPtrDeps[ReversePtrDepsToAdd.back().first]
+.insert(ReversePtrDepsToAdd.back().second);
+ReversePtrDepsToAdd.pop_back();
+}
+}
+assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
+AA->deleteValue(RemInst);
+DEBUG(verifyRemoved(RemInst));
+}
+/// verifyRemoved - Verify that the specified instruction does not occur
+/// in our internal data structures.
+void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {
+for (LocalDepMapType::const_iterator I = LocalDeps.begin(),
+E = LocalDeps.end(); I != E; ++I) {
+assert(I->first != D && "Inst occurs in data structures");
+assert(I->second.getInst() != D &&
+"Inst occurs in data structures");
+}
+for (CachedNonLocalPointerInfo::const_iterator I =NonLocalPointerDeps.begin(),
+E = NonLocalPointerDeps.end(); I != E; ++I) {
+assert(I->first.getPointer() != D && "Inst occurs in NLPD map key");
+const NonLocalDepInfo &Val = I->second.NonLocalDeps;
+for (NonLocalDepInfo::const_iterator II = Val.begin(), E = Val.end();
+II != E; ++II)
+assert(II->getResult().getInst() != D && "Inst occurs as NLPD value");
+}
+for (NonLocalDepMapType::const_iterator I = NonLocalDeps.begin(),
+E = NonLocalDeps.end(); I != E; ++I) {
+assert(I->first != D && "Inst occurs in data structures");
+const PerInstNLInfo &INLD = I->second;
+for (NonLocalDepInfo::const_iterator II = INLD.first.begin(),
+EE = INLD.first.end(); II  != EE; ++II)
+assert(II->getResult().getInst() != D && "Inst occurs in data structures");
+}
+for (ReverseDepMapType::const_iterator I = ReverseLocalDeps.begin(),
+E = ReverseLocalDeps.end(); I != E; ++I) {
+assert(I->first != D && "Inst occurs in data structures");
+for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
+EE = I->second.end(); II != EE; ++II)
+assert(*II != D && "Inst occurs in data structures");
+}
+for (ReverseDepMapType::const_iterator I = ReverseNonLocalDeps.begin(),
+E = ReverseNonLocalDeps.end();
+I != E; ++I) {
+assert(I->first != D && "Inst occurs in data structures");
+for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
+EE = I->second.end(); II != EE; ++II)
+assert(*II != D && "Inst occurs in data structures");
+}
+for (ReverseNonLocalPtrDepTy::const_iterator
+I = ReverseNonLocalPtrDeps.begin(),
+E = ReverseNonLocalPtrDeps.end(); I != E; ++I) {
+assert(I->first != D && "Inst occurs in rev NLPD map");
+for (SmallPtrSet<ValueIsLoadPair, 4>::const_iterator II = I->second.begin(),
+E = I->second.end(); II != E; ++II)
+assert(*II != ValueIsLoadPair(D, false) &&
+*II != ValueIsLoadPair(D, true) &&
+"Inst occurs in ReverseNonLocalPtrDeps map");
+}
+}

Mercurial > hg > Members > tobaru > cbc > CbC_llvm

comparison lib/Analysis/MemoryDependenceAnalysis.cpp @ 0:95c75e76d11b