#include "llvm/Target/TargetData.h"
using namespace llvm;
-// Control the calculation of non-local dependencies by only examining the
-// predecessors if the basic block has less than X amount (50 by default).
-static cl::opt<int>
-PredLimit("nonlocaldep-threshold", cl::Hidden, cl::init(50),
- cl::desc("Control the calculation of non-local"
- "dependencies (default = 50)"));
-
-STATISTIC(NumCacheNonlocal, "Number of cached non-local responses");
-STATISTIC(NumUncacheNonlocal, "Number of uncached non-local responses");
-
+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");
char MemoryDependenceAnalysis::ID = 0;
// Register this pass...
static RegisterPass<MemoryDependenceAnalysis> X("memdep",
"Memory Dependence Analysis", false, true);
-/// 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.getPointer() != D &&
- "Inst occurs in data structures");
- }
-
- for (nonLocalDepMapType::const_iterator I = depGraphNonLocal.begin(),
- E = depGraphNonLocal.end(); I != E; ++I) {
- assert(I->first != D && "Inst occurs in data structures");
- for (DenseMap<BasicBlock*, DepResultTy>::iterator II = I->second.begin(),
- EE = I->second.end(); II != EE; ++II)
- assert(II->second.getPointer() != D && "Inst occurs in data structures");
- }
-
- for (reverseDepMapType::const_iterator I = reverseDep.begin(),
- E = reverseDep.end(); I != E; ++I)
- 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 = reverseDepNonLocal.begin(),
- E = reverseDepNonLocal.end();
- I != E; ++I)
- 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");
-}
-
/// getAnalysisUsage - Does not modify anything. It uses Alias Analysis.
///
void MemoryDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredTransitive<TargetData>();
}
-/// getCallSiteDependency - Private helper for finding the local dependencies
-/// of a call site.
+bool MemoryDependenceAnalysis::runOnFunction(Function &) {
+ AA = &getAnalysis<AliasAnalysis>();
+ TD = &getAnalysis<TargetData>();
+ return false;
+}
+
+
+/// getCallSiteDependencyFrom - Private helper for finding the local
+/// dependencies of a call site.
MemDepResult MemoryDependenceAnalysis::
-getCallSiteDependency(CallSite C, BasicBlock::iterator ScanIt,
- BasicBlock *BB) {
- AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
- TargetData &TD = getAnalysis<TargetData>();
-
+getCallSiteDependencyFrom(CallSite CS, BasicBlock::iterator ScanIt,
+ BasicBlock *BB) {
// Walk backwards through the block, looking for dependencies
while (ScanIt != BB->begin()) {
Instruction *Inst = --ScanIt;
// If this inst is a memory op, get the pointer it accessed
- Value* pointer = 0;
- uint64_t pointerSize = 0;
- if (StoreInst* S = dyn_cast<StoreInst>(Inst)) {
- pointer = S->getPointerOperand();
- pointerSize = TD.getTypeStoreSize(S->getOperand(0)->getType());
- } else if (AllocationInst* AI = dyn_cast<AllocationInst>(Inst)) {
- pointer = AI;
- if (ConstantInt* C = dyn_cast<ConstantInt>(AI->getArraySize()))
- pointerSize = C->getZExtValue() *
- TD.getTypeStoreSize(AI->getAllocatedType());
- else
- pointerSize = ~0UL;
- } else if (VAArgInst* V = dyn_cast<VAArgInst>(Inst)) {
- pointer = V->getOperand(0);
- pointerSize = TD.getTypeStoreSize(V->getType());
- } else if (FreeInst* F = dyn_cast<FreeInst>(Inst)) {
- pointer = F->getPointerOperand();
+ Value *Pointer = 0;
+ uint64_t PointerSize = 0;
+ if (StoreInst *S = dyn_cast<StoreInst>(Inst)) {
+ Pointer = S->getPointerOperand();
+ PointerSize = TD->getTypeStoreSize(S->getOperand(0)->getType());
+ } else if (VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
+ Pointer = V->getOperand(0);
+ PointerSize = TD->getTypeStoreSize(V->getType());
+ } else if (FreeInst *F = dyn_cast<FreeInst>(Inst)) {
+ Pointer = F->getPointerOperand();
// FreeInsts erase the entire structure
- pointerSize = ~0UL;
- } else if (CallSite::get(Inst).getInstruction() != 0) {
- if (AA.getModRefBehavior(CallSite::get(Inst)) !=
- AliasAnalysis::DoesNotAccessMemory)
- return MemDepResult::get(Inst);
- continue;
- } else
- continue;
-
- if (AA.getModRefInfo(C, pointer, pointerSize) != AliasAnalysis::NoModRef)
- return MemDepResult::get(Inst);
- }
-
- // No dependence found.
- return MemDepResult::getNonLocal();
-}
-
-/// nonLocalHelper - Private helper used to calculate non-local dependencies
-/// by doing DFS on the predecessors of a block to find its dependencies.
-void MemoryDependenceAnalysis::nonLocalHelper(Instruction* query,
- BasicBlock* block,
- DenseMap<BasicBlock*, DepResultTy> &resp) {
- // Set of blocks that we've already visited in our DFS
- SmallPtrSet<BasicBlock*, 4> visited;
- // If we're updating a dirtied cache entry, we don't need to reprocess
- // already computed entries.
- for (DenseMap<BasicBlock*, DepResultTy>::iterator I = resp.begin(),
- E = resp.end(); I != E; ++I)
- if (I->second.getInt() != Dirty)
- visited.insert(I->first);
-
- // Current stack of the DFS
- SmallVector<BasicBlock*, 4> stack;
- for (pred_iterator PI = pred_begin(block), PE = pred_end(block);
- PI != PE; ++PI)
- stack.push_back(*PI);
-
- // Do a basic DFS
- while (!stack.empty()) {
- BasicBlock* BB = stack.back();
-
- // If we've already visited this block, no need to revist
- if (visited.count(BB)) {
- stack.pop_back();
- continue;
- }
-
- // If we find a new block with a local dependency for query,
- // then we insert the new dependency and backtrack.
- if (BB != block) {
- visited.insert(BB);
-
- MemDepResult localDep = getDependencyFrom(query, BB->end(), BB);
- if (!localDep.isNonLocal()) {
- resp.insert(std::make_pair(BB, ConvFromResult(localDep)));
- stack.pop_back();
+ PointerSize = ~0UL;
+ } else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
+ CallSite InstCS = CallSite::get(Inst);
+ // If these two calls do not interfere, look past it.
+ if (AA->getModRefInfo(CS, InstCS) == AliasAnalysis::NoModRef)
continue;
- }
- // If we re-encounter the starting block, we still need to search it
- // because there might be a dependency in the starting block AFTER
- // the position of the query. This is necessary to get loops right.
- } else if (BB == block) {
- visited.insert(BB);
- MemDepResult localDep = getDependencyFrom(query, BB->end(), BB);
- if (localDep.getInst() != query)
- resp.insert(std::make_pair(BB, ConvFromResult(localDep)));
+ // FIXME: If this is a ref/ref result, we should ignore it!
+ // X = strlen(P);
+ // Y = strlen(Q);
+ // Z = strlen(P); // Z = X
- stack.pop_back();
- continue;
- }
-
- // If we didn't find anything, recurse on the precessors of this block
- // Only do this for blocks with a small number of predecessors.
- bool predOnStack = false;
- bool inserted = false;
- if (std::distance(pred_begin(BB), pred_end(BB)) <= PredLimit) {
- for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
- PI != PE; ++PI)
- if (!visited.count(*PI)) {
- stack.push_back(*PI);
- inserted = true;
- } else
- predOnStack = true;
- }
-
- // If we inserted a new predecessor, then we'll come back to this block
- if (inserted)
+ // If they interfere, we generally return clobber. However, if they are
+ // calls to the same read-only functions we return Def.
+ if (!AA->onlyReadsMemory(CS) || CS.getCalledFunction() == 0 ||
+ CS.getCalledFunction() != InstCS.getCalledFunction())
+ return MemDepResult::getClobber(Inst);
+ return MemDepResult::getDef(Inst);
+ } else {
+ // Non-memory instruction.
continue;
- // If we didn't insert because we have no predecessors, then this
- // query has no dependency at all.
- else if (!inserted && !predOnStack) {
- resp.insert(std::make_pair(BB, DepResultTy(0, None)));
- // If we didn't insert because our predecessors are already on the stack,
- // then we might still have a dependency, but it will be discovered during
- // backtracking.
- } else if (!inserted && predOnStack){
- resp.insert(std::make_pair(BB, DepResultTy(0, NonLocal)));
- }
-
- stack.pop_back();
- }
-}
-
-/// 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 MemoryDependenceAnalysis::getNonLocalDependency(Instruction* query,
- DenseMap<BasicBlock*, MemDepResult> &resp) {
- if (depGraphNonLocal.count(query)) {
- DenseMap<BasicBlock*, DepResultTy> &cached = depGraphNonLocal[query];
- NumCacheNonlocal++;
-
- SmallVector<BasicBlock*, 4> dirtied;
- for (DenseMap<BasicBlock*, DepResultTy>::iterator I = cached.begin(),
- E = cached.end(); I != E; ++I)
- if (I->second.getInt() == Dirty)
- dirtied.push_back(I->first);
-
- for (SmallVector<BasicBlock*, 4>::iterator I = dirtied.begin(),
- E = dirtied.end(); I != E; ++I) {
- MemDepResult localDep = getDependencyFrom(query, (*I)->end(), *I);
- if (!localDep.isNonLocal())
- cached[*I] = ConvFromResult(localDep);
- else {
- cached.erase(*I);
- nonLocalHelper(query, *I, cached);
- }
- }
-
- // Update the reverse non-local dependency cache.
- for (DenseMap<BasicBlock*, DepResultTy>::iterator I = cached.begin(),
- E = cached.end(); I != E; ++I) {
- if (Instruction *Inst = I->second.getPointer())
- reverseDepNonLocal[Inst].insert(query);
- resp[I->first] = ConvToResult(I->second);
}
- return;
+ if (AA->getModRefInfo(CS, Pointer, PointerSize) != AliasAnalysis::NoModRef)
+ return MemDepResult::getClobber(Inst);
}
- NumUncacheNonlocal++;
-
- // If not, go ahead and search for non-local deps.
- DenseMap<BasicBlock*, DepResultTy> &cached = depGraphNonLocal[query];
- nonLocalHelper(query, query->getParent(), cached);
-
- // Update the non-local dependency cache
- for (DenseMap<BasicBlock*, DepResultTy>::iterator I = cached.begin(),
- E = cached.end(); I != E; ++I) {
- // FIXME: Merge with the code above!
- if (Instruction *Inst = I->second.getPointer())
- reverseDepNonLocal[Inst].insert(query);
- resp[I->first] = ConvToResult(I->second);
- }
+ // No dependence found.
+ return MemDepResult::getNonLocal();
}
-/// getDependency - Return the instruction on which a memory operation
-/// depends. The local parameter indicates if the query should only
-/// evaluate dependencies within the same basic block.
+/// getDependencyFrom - Return the instruction on which a memory operation
+/// depends.
MemDepResult MemoryDependenceAnalysis::
getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt,
BasicBlock *BB) {
- AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
- TargetData &TD = getAnalysis<TargetData>();
+ // The first instruction in a block is always non-local.
+ if (ScanIt == BB->begin())
+ return MemDepResult::getNonLocal();
// Get the pointer value for which dependence will be determined
Value *MemPtr = 0;
uint64_t MemSize = 0;
- bool MemVolatile = false;
- if (StoreInst* S = dyn_cast<StoreInst>(QueryInst)) {
- MemPtr = S->getPointerOperand();
- MemSize = TD.getTypeStoreSize(S->getOperand(0)->getType());
- MemVolatile = S->isVolatile();
- } else if (LoadInst* L = dyn_cast<LoadInst>(QueryInst)) {
- MemPtr = L->getPointerOperand();
- MemSize = TD.getTypeStoreSize(L->getType());
- MemVolatile = L->isVolatile();
- } else if (VAArgInst* V = dyn_cast<VAArgInst>(QueryInst)) {
- MemPtr = V->getOperand(0);
- MemSize = TD.getTypeStoreSize(V->getType());
- } else if (FreeInst* F = dyn_cast<FreeInst>(QueryInst)) {
- MemPtr = F->getPointerOperand();
+ if (StoreInst *SI = dyn_cast<StoreInst>(QueryInst)) {
+ // If this is a volatile store, don't mess around with it. Just return the
+ // previous instruction as a clobber.
+ if (SI->isVolatile())
+ return MemDepResult::getClobber(--ScanIt);
+
+ MemPtr = SI->getPointerOperand();
+ MemSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
+ } else if (LoadInst *LI = dyn_cast<LoadInst>(QueryInst)) {
+ // If this is a volatile load, don't mess around with it. Just return the
+ // previous instruction as a clobber.
+ if (LI->isVolatile())
+ return MemDepResult::getClobber(--ScanIt);
+
+ MemPtr = LI->getPointerOperand();
+ MemSize = TD->getTypeStoreSize(LI->getType());
+ } else if (FreeInst *FI = dyn_cast<FreeInst>(QueryInst)) {
+ MemPtr = FI->getPointerOperand();
// FreeInsts erase the entire structure, not just a field.
MemSize = ~0UL;
- } else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst))
- return getCallSiteDependency(CallSite::get(QueryInst), ScanIt, BB);
- else // Non-memory instructions depend on nothing.
- return MemDepResult::getNone();
+ } else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
+ assert(0 && "Should use getCallSiteDependencyFrom!");
+ return getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanIt, BB);
+ } else {
+ // Otherwise, this is a vaarg or non-memory instruction, just return a
+ // clobber dependency on the previous inst.
+ return MemDepResult::getClobber(--ScanIt);
+ }
// Walk backwards through the basic block, looking for dependencies
while (ScanIt != BB->begin()) {
Instruction *Inst = --ScanIt;
-
- // If this inst is a memory op, get the pointer it accessed
- Value *Pointer = 0;
- uint64_t PointerSize = 0;
- if (StoreInst *S = dyn_cast<StoreInst>(Inst)) {
- // All volatile loads/stores depend on each other.
- if (MemVolatile && S->isVolatile())
- return MemDepResult::get(S);
-
- Pointer = S->getPointerOperand();
- PointerSize = TD.getTypeStoreSize(S->getOperand(0)->getType());
- } else if (LoadInst *L = dyn_cast<LoadInst>(Inst)) {
- // All volatile loads/stores depend on each other
- if (MemVolatile && L->isVolatile())
- return MemDepResult::get(L);
-
- Pointer = L->getPointerOperand();
- PointerSize = TD.getTypeStoreSize(L->getType());
- } else if (AllocationInst *AI = dyn_cast<AllocationInst>(Inst)) {
- Pointer = AI;
- if (ConstantInt *C = dyn_cast<ConstantInt>(AI->getArraySize()))
- PointerSize = C->getZExtValue() *
- TD.getTypeStoreSize(AI->getAllocatedType());
- else
- PointerSize = ~0UL;
- } else if (VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
- Pointer = V->getOperand(0);
- PointerSize = TD.getTypeStoreSize(V->getType());
- } else if (FreeInst *F = dyn_cast<FreeInst>(Inst)) {
- Pointer = F->getPointerOperand();
+
+ // 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)) {
+ Value *Pointer = LI->getPointerOperand();
+ uint64_t PointerSize = TD->getTypeStoreSize(LI->getType());
- // FreeInsts erase the entire structure.
- PointerSize = ~0UL;
- } else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
- // Calls need special handling. Check if they can modify our pointer.
- AliasAnalysis::ModRefResult MR =
- AA.getModRefInfo(CallSite::get(Inst), MemPtr, MemSize);
+ // If we found a pointer, check if it could be the same as our pointer.
+ AliasAnalysis::AliasResult R =
+ AA->alias(Pointer, PointerSize, MemPtr, MemSize);
+ if (R == AliasAnalysis::NoAlias)
+ continue;
- if (MR == AliasAnalysis::NoModRef)
+ // May-alias loads don't depend on each other without a dependence.
+ if (isa<LoadInst>(QueryInst) && R == AliasAnalysis::MayAlias)
continue;
+ return MemDepResult::getDef(Inst);
+ }
+
+ if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ Value *Pointer = SI->getPointerOperand();
+ uint64_t PointerSize = TD->getTypeStoreSize(SI->getOperand(0)->getType());
+
+ // If we found a pointer, check if it could be the same as our pointer.
+ AliasAnalysis::AliasResult R =
+ AA->alias(Pointer, PointerSize, MemPtr, MemSize);
- // Loads don't depend on read-only calls
- if (isa<LoadInst>(QueryInst) && MR == AliasAnalysis::Ref)
+ if (R == AliasAnalysis::NoAlias)
continue;
+ if (R == AliasAnalysis::MayAlias)
+ return MemDepResult::getClobber(Inst);
+ return MemDepResult::getDef(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.
+ if (AllocationInst *AI = dyn_cast<AllocationInst>(Inst)) {
+ Value *AccessPtr = MemPtr->getUnderlyingObject();
- return MemDepResult::get(Inst);
- } else {
- // Non memory instruction, move to the next one.
+ if (AccessPtr == AI ||
+ AA->alias(AI, 1, AccessPtr, 1) == AliasAnalysis::MustAlias)
+ return MemDepResult::getDef(AI);
continue;
}
- // If we found a pointer, check if it could be the same as our pointer
- AliasAnalysis::AliasResult R =
- AA.alias(Pointer, PointerSize, MemPtr, MemSize);
-
- if (R == AliasAnalysis::NoAlias)
+ // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
+ if (AA->getModRefInfo(Inst, MemPtr, MemSize) == AliasAnalysis::NoModRef)
continue;
- // May-alias loads don't depend on each other without a dependence.
- if (isa<LoadInst>(QueryInst) && isa<LoadInst>(Inst) &&
- R == AliasAnalysis::MayAlias)
- continue;
- return MemDepResult::get(Inst);
+ // Otherwise, there is a dependence.
+ return MemDepResult::getClobber(Inst);
}
// If we found nothing, return the non-local flag.
Instruction *ScanPos = QueryInst;
// Check for a cached result
- DepResultTy &LocalCache = LocalDeps[QueryInst];
+ MemDepResult &LocalCache = LocalDeps[QueryInst];
- // If the cached entry is non-dirty, just return it.
- if (LocalCache.getInt() != Dirty)
- return ConvToResult(LocalCache);
+ // 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.getPointer())
+ if (Instruction *Inst = LocalCache.getInst()) {
ScanPos = Inst;
+
+ SmallPtrSet<Instruction*, 4> &InstMap = ReverseLocalDeps[Inst];
+ InstMap.erase(QueryInst);
+ if (InstMap.empty())
+ ReverseLocalDeps.erase(Inst);
+ }
// Do the scan.
- MemDepResult Res =
- getDependencyFrom(QueryInst, ScanPos, QueryInst->getParent());
+ if (!isa<CallInst>(QueryInst) && !isa<InvokeInst>(QueryInst))
+ LocalCache = getDependencyFrom(QueryInst, ScanPos, QueryInst->getParent());
+ else
+ LocalCache = getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanPos,
+ QueryInst->getParent());
// Remember the result!
- // FIXME: Don't convert back and forth! Make a shared helper function.
- LocalCache = ConvFromResult(Res);
- if (Instruction *I = Res.getInst())
- reverseDep[I].insert(QueryInst);
+ if (Instruction *I = LocalCache.getInst())
+ ReverseLocalDeps[I].insert(QueryInst);
- return Res;
+ return LocalCache;
}
+/// getNonLocalDependency - Perform a full dependency query for the
+/// specified instruction, 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.
+///
+const MemoryDependenceAnalysis::NonLocalDepInfo &
+MemoryDependenceAnalysis::getNonLocalDependency(Instruction *QueryInst) {
+ assert(getDependency(QueryInst).isNonLocal() &&
+ "getNonLocalDependency should only be used on insts with non-local deps!");
+ PerInstNLInfo &CacheP = NonLocalDeps[QueryInst];
+
+ NonLocalDepInfo &Cache = CacheP.first;
-/// 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 MemoryDependenceAnalysis::dropInstruction(Instruction* drop) {
- LocalDepMapType::iterator depGraphEntry = LocalDeps.find(drop);
- if (depGraphEntry != LocalDeps.end())
- if (Instruction *Inst = depGraphEntry->second.getPointer())
- reverseDep[Inst].erase(drop);
+ /// 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;
- // Drop dependency information for things that depended on this instr
- SmallPtrSet<Instruction*, 4>& set = reverseDep[drop];
- for (SmallPtrSet<Instruction*, 4>::iterator I = set.begin(), E = set.end();
+ 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)
- LocalDeps.erase(*I);
+ if (I->second.isDirty())
+ DirtyBlocks.push_back(I->first);
+
+ // 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 = QueryInst->getParent();
+ DirtyBlocks.append(pred_begin(QueryBB), pred_end(QueryBB));
+ NumUncacheNonLocal++;
+ }
- LocalDeps.erase(drop);
- reverseDep.erase(drop);
+ // Visited checked first, vector in sorted order.
+ SmallPtrSet<BasicBlock*, 64> Visited;
- for (DenseMap<BasicBlock*, DepResultTy>::iterator DI =
- depGraphNonLocal[drop].begin(), DE = depGraphNonLocal[drop].end();
- DI != DE; ++DI)
- if (Instruction *Inst = DI->second.getPointer())
- reverseDepNonLocal[Inst].erase(drop);
+ unsigned NumSortedEntries = Cache.size();
- if (reverseDepNonLocal.count(drop)) {
- SmallPtrSet<Instruction*, 4>& set =
- reverseDepNonLocal[drop];
- for (SmallPtrSet<Instruction*, 4>::iterator I = set.begin(), E = set.end();
- I != E; ++I)
- for (DenseMap<BasicBlock*, DepResultTy>::iterator DI =
- depGraphNonLocal[*I].begin(), DE = depGraphNonLocal[*I].end();
- DI != DE; ++DI)
- if (DI->second == DepResultTy(drop, Normal))
- // FIXME: Why not remember the old insertion point??
- DI->second = DepResultTy(0, Dirty);
+ // 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.
+ NonLocalDepInfo::iterator Entry =
+ std::upper_bound(Cache.begin(), Cache.begin()+NumSortedEntries,
+ std::make_pair(DirtyBB, MemDepResult()));
+ if (Entry != Cache.begin() && (&*Entry)[-1].first == DirtyBB)
+ --Entry;
+
+ MemDepResult *ExistingResult = 0;
+ if (Entry != Cache.begin()+NumSortedEntries &&
+ Entry->first == DirtyBB) {
+ // If we already have an entry, and if it isn't already dirty, the block
+ // is done.
+ if (!Entry->second.isDirty())
+ continue;
+
+ // Otherwise, remember this slot so we can update the value.
+ ExistingResult = &Entry->second;
+ }
+
+ // 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->getInst()) {
+ ScanPos = Inst;
+
+ // We're removing QueryInst's use of Inst.
+ SmallPtrSet<Instruction*, 4> &InstMap = ReverseNonLocalDeps[Inst];
+ InstMap.erase(QueryInst);
+ if (InstMap.empty()) ReverseNonLocalDeps.erase(Inst);
+ }
+ }
+
+ // Find out if this block has a local dependency for QueryInst.
+ MemDepResult Dep;
+ if (!isa<CallInst>(QueryInst) && !isa<InvokeInst>(QueryInst))
+ Dep = getDependencyFrom(QueryInst, ScanPos, DirtyBB);
+ else
+ Dep = getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanPos,
+ DirtyBB);
+
+ // If we had a dirty entry for the block, update it. Otherwise, just add
+ // a new entry.
+ if (ExistingResult)
+ *ExistingResult = Dep;
+ else
+ Cache.push_back(std::make_pair(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(QueryInst);
+ } else {
+
+ // If the block *is* completely transparent to the load, we need to check
+ // the predecessors of this block. Add them to our worklist.
+ DirtyBlocks.append(pred_begin(DirtyBB), pred_end(DirtyBB));
+ }
}
- reverseDepNonLocal.erase(drop);
- depGraphNonLocal.erase(drop);
+ return Cache;
}
+
/// 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.
- for (DenseMap<BasicBlock*, DepResultTy>::iterator DI =
- depGraphNonLocal[RemInst].begin(), DE = depGraphNonLocal[RemInst].end();
- DI != DE; ++DI)
- if (Instruction *Inst = DI->second.getPointer())
- reverseDepNonLocal[Inst].erase(RemInst);
+ 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->second.getInst())
+ ReverseNonLocalDeps[Inst].erase(RemInst);
+ NonLocalDeps.erase(NLDI);
+ }
- // Shortly after this, we will look for things that depend on RemInst. In
- // order to update these, we'll need a new dependency to base them on. We
- // could completely delete any entries that depend on this, but it is better
- // to make a more accurate approximation where possible. Compute that better
- // approximation if we can.
- DepResultTy NewDependency;
-
// If we have a cached local dependence query for this instruction, remove it.
//
LocalDepMapType::iterator LocalDepEntry = LocalDeps.find(RemInst);
if (LocalDepEntry != LocalDeps.end()) {
- DepResultTy LocalDep = LocalDepEntry->second;
-
- // Remove this local dependency info.
- LocalDeps.erase(LocalDepEntry);
-
// Remove us from DepInst's reverse set now that the local dep info is gone.
- if (Instruction *Inst = LocalDep.getPointer())
- reverseDep[Inst].erase(RemInst);
-
- // If we have unconfirmed info, don't trust it.
- if (LocalDep.getInt() != Dirty) {
- // If we have a confirmed non-local flag, use it.
- if (LocalDep.getInt() == NonLocal || LocalDep.getInt() == None) {
- // The only time this dependency is confirmed is if it is non-local.
- NewDependency = LocalDep;
- } else {
- // If we have dep info for RemInst, set them to it.
- Instruction *NDI = next(BasicBlock::iterator(LocalDep.getPointer()));
- if (NDI != RemInst) // Don't use RemInst for the new dependency!
- NewDependency = DepResultTy(NDI, Dirty);
- }
+ if (Instruction *Inst = LocalDepEntry->second.getInst()) {
+ SmallPtrSet<Instruction*, 4> &RLD = ReverseLocalDeps[Inst];
+ RLD.erase(RemInst);
+ if (RLD.empty())
+ ReverseLocalDeps.erase(Inst);
}
- }
-
- // If we don't already have a local dependency answer for this instruction,
- // use the immediate successor of RemInst. We use the successor because
- // getDependence starts by checking the immediate predecessor of what is in
- // the cache.
- if (NewDependency == DepResultTy(0, Dirty))
- NewDependency = DepResultTy(next(BasicBlock::iterator(RemInst)), Dirty);
+
+ // Remove this local dependency info.
+ LocalDeps.erase(LocalDepEntry);
+ }
// Loop over all of the things that depend on the instruction we're removing.
//
- reverseDepMapType::iterator ReverseDepIt = reverseDep.find(RemInst);
- if (ReverseDepIt != reverseDep.end()) {
+ SmallVector<std::pair<Instruction*, Instruction*>, 8> ReverseDepsToAdd;
+
+ 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 stuff depending on it.
+ assert(!ReverseDeps.empty() && !isa<TerminatorInst>(RemInst) &&
+ "Nothing can locally depend on a terminator");
+
+ // Anything that was locally dependent on RemInst is now going to be
+ // dependent on the instruction after RemInst. It will have the dirty flag
+ // set so it will rescan. This saves having to scan the entire block to get
+ // to this point.
+ Instruction *NewDepInst = next(BasicBlock::iterator(RemInst));
+
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] = MemDepResult::getDirty(NewDepInst);
- // If we thought the instruction depended on itself (possible for
- // unconfirmed dependencies) ignore the update.
- if (InstDependingOnRemInst == RemInst) continue;
-
- // Insert the new dependencies.
- LocalDeps[InstDependingOnRemInst] = NewDependency;
-
- // If our NewDependency is an instruction, make sure to remember that new
- // things depend on it.
- if (Instruction *Inst = NewDependency.getPointer())
- reverseDep[Inst].insert(InstDependingOnRemInst);
+ // Make sure to remember that new things depend on NewDepInst.
+ ReverseDepsToAdd.push_back(std::make_pair(NewDepInst,
+ 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();
}
- reverseDep.erase(RemInst);
}
- ReverseDepIt = reverseDepNonLocal.find(RemInst);
- if (ReverseDepIt != reverseDepNonLocal.end()) {
+ 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)
- for (DenseMap<BasicBlock*, DepResultTy>::iterator DI =
- depGraphNonLocal[*I].begin(), DE = depGraphNonLocal[*I].end();
- DI != DE; ++DI)
- if (DI->second == DepResultTy(RemInst, Normal))
- // FIXME: Why not remember the old insertion point??
- DI->second = DepResultTy(0, Dirty);
- reverseDepNonLocal.erase(ReverseDepIt);
+ 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->second.getInst() != RemInst) continue;
+
+ // Convert to a dirty entry for the subsequent instruction.
+ Instruction *NextI = 0;
+ if (!RemInst->isTerminator()) {
+ NextI = next(BasicBlock::iterator(RemInst));
+ ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
+ }
+ DI->second = MemDepResult::getDirty(NextI);
+ }
+ }
+
+ 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();
+ }
}
- depGraphNonLocal.erase(RemInst);
+ assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
+ AA->deleteValue(RemInst);
+ DEBUG(verifyRemoved(RemInst));
+}
- getAnalysis<AliasAnalysis>().deleteValue(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");
+ }
- DEBUG(verifyRemoved(RemInst));
+ 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->second.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");
+ }
}
projects / oota-llvm.git / blobdiff