+/// 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(Value *Pointer, bool isLoad, BasicBlock *FromBB,
+ SmallVectorImpl<NonLocalDepEntry> &Result) {
+ assert(isa<PointerType>(Pointer->getType()) &&
+ "Can't get pointer deps of a non-pointer!");
+ Result.clear();
+
+ // We know that the pointer value is live into FromBB find the def/clobbers
+ // from presecessors.
+ const Type *EltTy = cast<PointerType>(Pointer->getType())->getElementType();
+ uint64_t PointeeSize = TD->getTypeStoreSize(EltTy);
+
+ // 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(Pointer, PointeeSize, isLoad, FromBB,
+ Result, Visited, true))
+ return;
+ Result.clear();
+ Result.push_back(std::make_pair(FromBB,
+ MemDepResult::getClobber(FromBB->begin())));
+}
+
+/// 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(Value *Pointer, uint64_t PointeeSize,
+ 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,
+ std::make_pair(BB, MemDepResult()));
+ if (Entry != Cache->begin() && prior(Entry)->first == BB)
+ --Entry;
+
+ MemDepResult *ExistingResult = 0;
+ if (Entry != Cache->begin()+NumSortedEntries && Entry->first == BB)
+ ExistingResult = &Entry->second;
+
+ // If we have a cached entry, and it is non-dirty, use it as the value for
+ // this dependency.
+ if (ExistingResult && !ExistingResult->isDirty()) {
+ ++NumCacheNonLocalPtr;
+ return *ExistingResult;
+ }
+
+ // 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->getInst()) {
+ assert(ExistingResult->getInst()->getParent() == BB &&
+ "Instruction invalidated?");
+ ++NumCacheDirtyNonLocalPtr;
+ ScanPos = ExistingResult->getInst();
+
+ // Eliminating the dirty entry from 'Cache', so update the reverse info.
+ ValueIsLoadPair CacheKey(Pointer, isLoad);
+ RemoveFromReverseMap(ReverseNonLocalPtrDeps, ScanPos,
+ CacheKey.getOpaqueValue());
+ } else {
+ ++NumUncacheNonLocalPtr;
+ }
+
+ // Scan the block for the dependency.
+ MemDepResult Dep = getPointerDependencyFrom(Pointer, PointeeSize, isLoad,
+ ScanPos, BB);
+
+ // 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(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.isNonLocal())
+ 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(Pointer, isLoad);
+ ReverseNonLocalPtrDeps[Inst].insert(CacheKey.getOpaqueValue());
+ return Dep;
+}
+
+
+/// 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(Value *Pointer, uint64_t PointeeSize,
+ bool isLoad, BasicBlock *StartBB,
+ SmallVectorImpl<NonLocalDepEntry> &Result,
+ DenseMap<BasicBlock*, Value*> &Visited,
+ bool SkipFirstBlock) {
+
+ // Look up the cached info for Pointer.
+ ValueIsLoadPair CacheKey(Pointer, isLoad);
+
+ std::pair<BBSkipFirstBlockPair, NonLocalDepInfo> *CacheInfo =
+ &NonLocalPointerDeps[CacheKey];
+ NonLocalDepInfo *Cache = &CacheInfo->second;
+
+ // If we have valid cached information for exactly the block we are
+ // investigating, just return it with no recomputation.
+ if (CacheInfo->first == 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->first);
+ if (VI == Visited.end() || VI->second == Pointer) 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;
+ }
+ }
+
+ for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
+ I != E; ++I) {
+ Visited.insert(std::make_pair(I->first, Pointer));
+ if (!I->second.isNonLocal())
+ Result.push_back(*I);
+ }
+ ++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->first = BBSkipFirstBlockPair(StartBB, SkipFirstBlock);
+ else
+ CacheInfo->first = BBSkipFirstBlockPair();
+
+ SmallVector<BasicBlock*, 32> Worklist;
+ Worklist.push_back(StartBB);
+
+ // 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(Pointer, PointeeSize, isLoad,
+ BB, Cache, NumSortedEntries);
+
+ // If we got a Def or Clobber, add this to the list of results.
+ if (!Dep.isNonLocal()) {
+ Result.push_back(NonLocalDepEntry(BB, Dep));
+ 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 phi translation fails, then we can't continue dependence analysis.
+ Instruction *PtrInst = dyn_cast<Instruction>(Pointer);
+ bool NeedsPHITranslation = PtrInst && PtrInst->getParent() == BB;
+
+ // If no PHI translation is needed, just add all the predecessors of this
+ // block to scan them as well.
+ if (!NeedsPHITranslation) {
+ SkipFirstBlock = false;
+ 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));
+ if (InsertRes.second) {
+ // First time we've looked at *PI.
+ Worklist.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)
+ goto PredTranslationFailure;
+ }
+ continue;
+ }
+
+ // If we do need to do phi translation, then there are a bunch of different
+ // cases, because we have to find a Value* live in the predecessor block. We
+ // know that PtrInst is defined in this block at least.
+
+ // If this is directly a PHI node, just use the incoming values for each
+ // pred as the phi translated version.
+ if (PHINode *PtrPHI = dyn_cast<PHINode>(PtrInst)) {
+ for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
+ BasicBlock *Pred = *PI;
+ Value *PredPtr = PtrPHI->getIncomingValueForBlock(Pred);
+
+ // 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, PredPtr));
+
+ if (!InsertRes.second) {
+ // If the predecessor was visited with PredPtr, then we already did
+ // the analysis and can ignore it.
+ if (InsertRes.first->second == PredPtr)
+ 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.
+ 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 that could reuse the cache
+ // value will only see properly sorted cache arrays.
+ if (Cache && NumSortedEntries != Cache->size())
+ std::sort(Cache->begin(), Cache->end());
+ Cache = 0;
+
+ // 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 we have a problem phi translating, fall through to the code below
+ // to handle the failure condition.
+ if (getNonLocalPointerDepFromBB(PredPtr, PointeeSize, isLoad, Pred,
+ Result, Visited))
+ goto PredTranslationFailure;
+ }
+
+ // Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
+ CacheInfo = &NonLocalPointerDeps[CacheKey];
+ Cache = &CacheInfo->second;
+ 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->first = BBSkipFirstBlockPair();
+ SkipFirstBlock = false;
+ continue;
+ }
+
+ // TODO: BITCAST, GEP.
+
+ // cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
+ // if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst))
+ // cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0);
+ PredTranslationFailure:
+
+ if (Cache == 0) {
+ // Refresh the CacheInfo/Cache pointer if it got invalidated.
+ CacheInfo = &NonLocalPointerDeps[CacheKey];
+ Cache = &CacheInfo->second;
+ NumSortedEntries = Cache->size();
+ } else if (NumSortedEntries != Cache->size()) {
+ std::sort(Cache->begin(), Cache->end());
+ 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->first = BBSkipFirstBlockPair();
+
+ // If *nothing* works, mark the pointer as being clobbered by the first
+ // instruction in this block.
+ //
+ // 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->first != BB)
+ continue;
+
+ assert(I->second.isNonLocal() &&
+ "Should only be here with transparent block");
+ I->second = MemDepResult::getClobber(BB->begin());
+ ReverseNonLocalPtrDeps[BB->begin()].insert(CacheKey.getOpaqueValue());
+ Result.push_back(*I);
+ break;
+ }
+ }
+
+ // Okay, we're done now. If we added new values to the cache, re-sort it.
+ 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();
+ 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();
+ 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());
+ }
+ 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.second;
+
+ for (unsigned i = 0, e = PInfo.size(); i != e; ++i) {
+ Instruction *Target = PInfo[i].second.getInst();
+ if (Target == 0) continue; // Ignore non-local dep results.
+ assert(Target->getParent() == PInfo[i].first);
+
+ // Eliminating the dirty entry from 'Cache', so update the reverse info.
+ RemoveFromReverseMap(ReverseNonLocalPtrDeps, Target, P.getOpaqueValue());
+ }
+
+ // 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 (!isa<PointerType>(Ptr->getType())) return;
+ // Flush store info for the pointer.
+ RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, false));
+ // Flush load info for the pointer.
+ RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, true));
+}
+