#include "llvm/Target/TargetData.h"
using namespace llvm;
-STATISTIC(NumCacheNonLocal, "Number of cached 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...
AU.addRequiredTransitive<TargetData>();
}
-/// getCallSiteDependency - Private helper for finding the local dependencies
-/// of a call site.
-MemoryDependenceAnalysis::DepResultTy MemoryDependenceAnalysis::
-getCallSiteDependency(CallSite C, BasicBlock::iterator ScanIt,
- BasicBlock *BB) {
- AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
- TargetData &TD = getAnalysis<TargetData>();
-
+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::
+getCallSiteDependencyFrom(CallSite CS, BasicBlock::iterator ScanIt,
+ BasicBlock *BB) {
// Walk backwards through the block, looking for dependencies
while (ScanIt != BB->begin()) {
Instruction *Inst = --ScanIt;
uint64_t PointerSize = 0;
if (StoreInst *S = dyn_cast<StoreInst>(Inst)) {
Pointer = S->getPointerOperand();
- PointerSize = TD.getTypeStoreSize(S->getOperand(0)->getType());
+ PointerSize = TD->getTypeStoreSize(S->getOperand(0)->getType());
} else if (VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
Pointer = V->getOperand(0);
- PointerSize = TD.getTypeStoreSize(V->getType());
+ 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 (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
- if (AA.getModRefBehavior(CallSite::get(Inst)) ==
- AliasAnalysis::DoesNotAccessMemory)
+ CallSite InstCS = CallSite::get(Inst);
+ // If these two calls do not interfere, look past it.
+ if (AA->getModRefInfo(CS, InstCS) == AliasAnalysis::NoModRef)
continue;
- return DepResultTy(Inst, Normal);
+
+ // FIXME: If this is a ref/ref result, we should ignore it!
+ // X = strlen(P);
+ // Y = strlen(Q);
+ // Z = strlen(P); // Z = X
+
+ // 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 (AA.getModRefInfo(C, Pointer, PointerSize) != AliasAnalysis::NoModRef)
- return DepResultTy(Inst, Normal);
+ if (AA->getModRefInfo(CS, Pointer, PointerSize) != AliasAnalysis::NoModRef)
+ return MemDepResult::getClobber(Inst);
}
// No dependence found.
- return DepResultTy(0, NonLocal);
+ 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.
-MemoryDependenceAnalysis::DepResultTy MemoryDependenceAnalysis::
-getDependencyFromInternal(Instruction *QueryInst, BasicBlock::iterator ScanIt,
- BasicBlock *BB) {
- AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
- TargetData &TD = getAnalysis<TargetData>();
+/// getDependencyFrom - Return the instruction on which a memory operation
+/// depends.
+MemDepResult MemoryDependenceAnalysis::
+getDependencyFrom(Instruction *QueryInst, BasicBlock::iterator ScanIt,
+ BasicBlock *BB) {
+ // 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 DepResultTy(0, None);
+ } 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 the access is volatile and this is a volatile load/store, return a
- // dependence.
- if (MemVolatile &&
- ((isa<LoadInst>(Inst) && cast<LoadInst>(Inst)->isVolatile()) ||
- (isa<StoreInst>(Inst) && cast<StoreInst>(Inst)->isVolatile())))
- return DepResultTy(Inst, Normal);
-
// 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 *L = dyn_cast<LoadInst>(Inst)) {
- Value *Pointer = L->getPointerOperand();
- uint64_t PointerSize = TD.getTypeStoreSize(L->getType());
+ if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
+ Value *Pointer = LI->getPointerOperand();
+ uint64_t PointerSize = TD->getTypeStoreSize(LI->getType());
- // If we found a pointer, check if it could be the same as our pointer
+ // If we found a pointer, check if it could be the same as our pointer.
AliasAnalysis::AliasResult R =
- AA.alias(Pointer, PointerSize, MemPtr, MemSize);
-
+ AA->alias(Pointer, PointerSize, MemPtr, MemSize);
if (R == AliasAnalysis::NoAlias)
continue;
// May-alias loads don't depend on each other without a dependence.
if (isa<LoadInst>(QueryInst) && R == AliasAnalysis::MayAlias)
continue;
- return DepResultTy(Inst, Normal);
+ 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);
+
+ 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 None. This means that there is no dependence and
+ // 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();
if (AccessPtr == AI ||
- AA.alias(AI, 1, AccessPtr, 1) == AliasAnalysis::MustAlias)
- return DepResultTy(0, None);
+ AA->alias(AI, 1, AccessPtr, 1) == AliasAnalysis::MustAlias)
+ return MemDepResult::getDef(AI);
continue;
}
- // See if this instruction mod/ref's the pointer.
- AliasAnalysis::ModRefResult MRR = AA.getModRefInfo(Inst, MemPtr, MemSize);
-
- if (MRR == AliasAnalysis::NoModRef)
- continue;
-
- // Loads don't depend on read-only instructions.
- if (isa<LoadInst>(QueryInst) && MRR == AliasAnalysis::Ref)
+ // See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
+ if (AA->getModRefInfo(Inst, MemPtr, MemSize) == AliasAnalysis::NoModRef)
continue;
// Otherwise, there is a dependence.
- return DepResultTy(Inst, Normal);
+ return MemDepResult::getClobber(Inst);
}
// If we found nothing, return the non-local flag.
- return DepResultTy(0, NonLocal);
+ return MemDepResult::getNonLocal();
}
/// getDependency - Return the instruction on which a memory operation
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. Note that this depends
- // on DepResultTy's default constructing to 'dirty'.
- if (LocalCache.getInt() != Dirty)
- return ConvToResult(LocalCache);
+ // 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];
}
// Do the scan.
- LocalCache = getDependencyFromInternal(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!
- if (Instruction *I = LocalCache.getPointer())
+ if (Instruction *I = LocalCache.getInst())
ReverseLocalDeps[I].insert(QueryInst);
- return ConvToResult(LocalCache);
+ return LocalCache;
}
/// getNonLocalDependency - Perform a full dependency query for the
/// This method assumes the instruction returns a "nonlocal" dependency
/// within its own block.
///
-void MemoryDependenceAnalysis::
-getNonLocalDependency(Instruction *QueryInst,
- SmallVectorImpl<std::pair<BasicBlock*,
- MemDepResult> > &Result) {
+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];
- if (CacheP.getPointer() == 0) CacheP.setPointer(new NonLocalDepInfo());
- NonLocalDepInfo &Cache = *CacheP.getPointer();
+ 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
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. The
- // Int bit of CacheP tells us if we have anything dirty.
- if (CacheP.getInt())
- for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end();
- I != E; ++I)
- if (I->second.getInt() == Dirty)
- DirtyBlocks.push_back(I->first);
+ // determine what is dirty, seeding our initial DirtyBlocks worklist.
+ for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end();
+ I != E; ++I)
+ if (I->second.isDirty())
+ DirtyBlocks.push_back(I->first);
- NumCacheNonLocal++;
+ // 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 {
NumUncacheNonLocal++;
}
+ // Visited checked first, vector in sorted order.
+ SmallPtrSet<BasicBlock*, 64> Visited;
+
+ unsigned NumSortedEntries = Cache.size();
+
// Iterate while we still have blocks to update.
while (!DirtyBlocks.empty()) {
BasicBlock *DirtyBB = DirtyBlocks.back();
DirtyBlocks.pop_back();
- // Get the entry for this block. Note that this relies on DepResultTy
- // default initializing to Dirty.
- DepResultTy &DirtyBBEntry = Cache[DirtyBB];
+ // 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 DirtyBBEntry isn't dirty, it ended up on the worklist multiple times.
- if (DirtyBBEntry.getInt() != Dirty) continue;
-
// 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 (Instruction *Inst = DirtyBBEntry.getPointer()) {
- ScanPos = Inst;
+ if (ExistingResult) {
+ if (Instruction *Inst = ExistingResult->getInst()) {
+ ScanPos = Inst;
- // We're removing QueryInst's dependence on Inst.
- SmallPtrSet<Instruction*, 4> &InstMap = ReverseNonLocalDeps[Inst];
- InstMap.erase(QueryInst);
- if (InstMap.empty()) ReverseNonLocalDeps.erase(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.
- DirtyBBEntry = getDependencyFromInternal(QueryInst, ScanPos, DirtyBB);
-
+ 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 it!
- if (DirtyBBEntry.getInt() != NonLocal) {
+ // 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 = DirtyBBEntry.getPointer())
+ if (Instruction *Inst = Dep.getInst())
ReverseNonLocalDeps[Inst].insert(QueryInst);
- continue;
- }
+ } 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));
+ // 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));
+ }
}
-
- // Copy the result into the output set.
- for (NonLocalDepInfo::iterator I = Cache.begin(), E = Cache.end(); I != E;++I)
- Result.push_back(std::make_pair(I->first, ConvToResult(I->second)));
+ 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.
// for any cached queries.
NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst);
if (NLDI != NonLocalDeps.end()) {
- NonLocalDepInfo &BlockMap = *NLDI->second.getPointer();
+ NonLocalDepInfo &BlockMap = NLDI->second.first;
for (NonLocalDepInfo::iterator DI = BlockMap.begin(), DE = BlockMap.end();
DI != DE; ++DI)
- if (Instruction *Inst = DI->second.getPointer())
+ if (Instruction *Inst = DI->second.getInst())
ReverseNonLocalDeps[Inst].erase(RemInst);
- delete &BlockMap;
NonLocalDeps.erase(NLDI);
}
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.getPointer()) {
+ if (Instruction *Inst = LocalDepEntry->second.getInst()) {
SmallPtrSet<Instruction*, 4> &RLD = ReverseLocalDeps[Inst];
RLD.erase(RemInst);
if (RLD.empty())
assert(InstDependingOnRemInst != RemInst &&
"Already removed our local dep info");
- LocalDeps[InstDependingOnRemInst] = DepResultTy(NewDepInst, Dirty);
+ LocalDeps[InstDependingOnRemInst] = MemDepResult::getDirty(NewDepInst);
// Make sure to remember that new things depend on NewDepInst.
ReverseDepsToAdd.push_back(std::make_pair(NewDepInst,
assert(*I != RemInst && "Already removed NonLocalDep info for RemInst");
PerInstNLInfo &INLD = NonLocalDeps[*I];
- assert(INLD.getPointer() != 0 && "Reverse mapping out of date?");
// The information is now dirty!
- INLD.setInt(true);
+ INLD.second = true;
- for (NonLocalDepInfo::iterator DI = INLD.getPointer()->begin(),
- DE = INLD.getPointer()->end(); DI != DE; ++DI) {
- if (DI->second.getPointer() != RemInst) continue;
+ 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.
- DI->second.setInt(Dirty);
- if (RemInst->isTerminator())
- DI->second.setPointer(0);
- else {
- Instruction *NextI = next(BasicBlock::iterator(RemInst));
- DI->second.setPointer(NextI);
+ Instruction *NextI = 0;
+ if (!RemInst->isTerminator()) {
+ NextI = next(BasicBlock::iterator(RemInst));
ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
}
+ DI->second = MemDepResult::getDirty(NextI);
}
}
}
assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
- getAnalysis<AliasAnalysis>().deleteValue(RemInst);
+ AA->deleteValue(RemInst);
DEBUG(verifyRemoved(RemInst));
}
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 &&
+ assert(I->second.getInst() != D &&
"Inst occurs in data structures");
}
E = NonLocalDeps.end(); I != E; ++I) {
assert(I->first != D && "Inst occurs in data structures");
const PerInstNLInfo &INLD = I->second;
- for (NonLocalDepInfo::iterator II = INLD.getPointer()->begin(),
- EE = INLD.getPointer()->end(); II != EE; ++II)
- assert(II->second.getPointer() != D && "Inst occurs in data structures");
+ 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(),
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