#include "llvm/Function.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/ADT/Statistic.h"
-#include "llvm/Support/CFG.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/PredIteratorCache.h"
#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetData.h"
using namespace llvm;
"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");
char MemoryDependenceAnalysis::ID = 0;
static RegisterPass<MemoryDependenceAnalysis> X("memdep",
"Memory Dependence Analysis", false, true);
+MemoryDependenceAnalysis::MemoryDependenceAnalysis()
+: FunctionPass(&ID), PredCache(0) {
+}
+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 {
bool MemoryDependenceAnalysis::runOnFunction(Function &) {
AA = &getAnalysis<AliasAnalysis>();
TD = &getAnalysis<TargetData>();
+ if (PredCache == 0)
+ PredCache.reset(new PredIteratorCache());
return false;
}
/// getCallSiteDependencyFrom - Private helper for finding the local
/// dependencies of a call site.
MemDepResult MemoryDependenceAnalysis::
-getCallSiteDependencyFrom(CallSite CS, BasicBlock::iterator ScanIt,
- BasicBlock *BB) {
+getCallSiteDependencyFrom(CallSite CS, bool isReadOnlyCall,
+ BasicBlock::iterator ScanIt, BasicBlock *BB) {
// Walk backwards through the block, looking for dependencies
while (ScanIt != BB->begin()) {
Instruction *Inst = --ScanIt;
} 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)
+ switch (AA->getModRefInfo(CS, InstCS)) {
+ case AliasAnalysis::NoModRef:
+ // If the two calls don't interact (e.g. InstCS is readnone) keep
+ // scanning.
continue;
-
- // 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())
+ case AliasAnalysis::Ref:
+ // If the two calls read the same memory locations and CS is a readonly
+ // function, then we have two cases: 1) the calls may not interfere with
+ // each other at all. 2) the calls may produce the same value. In case
+ // #1 we want to ignore the values, in case #2, we want to return Inst
+ // as a Def dependence. This allows us to CSE in cases like:
+ // X = strlen(P);
+ // memchr(...);
+ // Y = strlen(P); // Y = X
+ if (isReadOnlyCall) {
+ if (CS.getCalledFunction() != 0 &&
+ CS.getCalledFunction() == InstCS.getCalledFunction())
+ return MemDepResult::getDef(Inst);
+ // Ignore unrelated read/read call dependences.
+ continue;
+ }
+ // FALL THROUGH
+ default:
return MemDepResult::getClobber(Inst);
- return MemDepResult::getDef(Inst);
+ }
} else {
// Non-memory instruction.
continue;
}
// See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
- // FIXME: If this is a load, we should ignore readonly calls!
- if (AA->getModRefInfo(Inst, MemPtr, MemSize) == AliasAnalysis::NoModRef)
+ switch (AA->getModRefInfo(Inst, MemPtr, MemSize)) {
+ case AliasAnalysis::NoModRef:
+ // If the call has no effect on the queried pointer, just ignore it.
continue;
-
- // Otherwise, there is a dependence.
- 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;
+ // FALL THROUGH.
+ 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 a
MemSize = TD->getTypeStoreSize(LI->getType());
}
} else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
- LocalCache = getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanPos,
+ CallSite QueryCS = CallSite::get(QueryInst);
+ bool isReadOnly = AA->onlyReadsMemory(QueryCS);
+ LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos,
QueryParent);
} else if (FreeInst *FI = dyn_cast<FreeInst>(QueryInst)) {
MemPtr = FI->getPointerOperand();
return LocalCache;
}
-/// getNonLocalDependency - Perform a full dependency query for the
-/// specified instruction, returning the set of blocks that the value is
+#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-1] <= Cache[i] && "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
+/// 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::getNonLocalDependency(Instruction *QueryInst) {
- // FIXME: Make this only be for callsites in the future.
- assert(isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst) ||
- isa<LoadInst>(QueryInst) || isa<StoreInst>(QueryInst));
- assert(getDependency(QueryInst).isNonLocal() &&
- "getNonLocalDependency should only be used on insts with non-local deps!");
- PerInstNLInfo &CacheP = NonLocalDeps[QueryInst];
+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
// << 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));
+ BasicBlock *QueryBB = QueryCS.getInstruction()->getParent();
+ for (BasicBlock **PI = PredCache->GetPreds(QueryBB); *PI; ++PI)
+ DirtyBlocks.push_back(*PI);
NumUncacheNonLocal++;
}
- // Visited checked first, vector in sorted order.
+ // 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()) {
// 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,
std::make_pair(DirtyBB, MemDepResult()));
- if (Entry != Cache.begin() && (&*Entry)[-1].first == DirtyBB)
+ if (Entry != Cache.begin() && prior(Entry)->first == DirtyBB)
--Entry;
MemDepResult *ExistingResult = 0;
if (Instruction *Inst = ExistingResult->getInst()) {
ScanPos = Inst;
// We're removing QueryInst's use of Inst.
- RemoveFromReverseMap(ReverseNonLocalDeps, Inst, QueryInst);
+ RemoveFromReverseMap(ReverseNonLocalDeps, Inst,
+ QueryCS.getInstruction());
}
}
// Find out if this block has a local dependency for QueryInst.
MemDepResult Dep;
- Value *MemPtr = 0;
- uint64_t MemSize = 0;
-
- if (ScanPos == DirtyBB->begin()) {
- // No dependence found. If this is the entry block of the function, it is a
- // clobber, otherwise it is non-local.
- if (DirtyBB != &DirtyBB->getParent()->getEntryBlock())
- Dep = MemDepResult::getNonLocal();
- else
- Dep = MemDepResult::getClobber(ScanPos);
- } else 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())
- Dep = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
- else {
- 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())
- Dep = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos));
- else {
- MemPtr = LI->getPointerOperand();
- MemSize = TD->getTypeStoreSize(LI->getType());
- }
+ 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 non-local.
+ Dep = MemDepResult::getNonLocal();
} else {
- assert(isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst));
- Dep = getCallSiteDependencyFrom(CallSite::get(QueryInst), ScanPos,
- DirtyBB);
+ Dep = MemDepResult::getClobber(ScanPos);
}
- if (MemPtr)
- Dep = getPointerDependencyFrom(MemPtr, MemSize, isa<LoadInst>(QueryInst),
- ScanPos, DirtyBB);
-
// If we had a dirty entry for the block, update it. Otherwise, just add
// a new entry.
if (ExistingResult)
// 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);
+ 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.
- DirtyBlocks.append(pred_begin(DirtyBB), pred_end(DirtyBB));
+ for (BasicBlock **PI = PredCache->GetPreds(DirtyBB); *PI; ++PI)
+ DirtyBlocks.push_back(*PI);
}
}
const Type *EltTy = cast<PointerType>(Pointer->getType())->getElementType();
uint64_t PointeeSize = TD->getTypeStoreSize(EltTy);
- // While we have blocks to analyze, get their values.
- SmallPtrSet<BasicBlock*, 64> Visited;
+ // 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) {
- for (pred_iterator PI = pred_begin(FromBB), E = pred_end(FromBB); PI != E;
- ++PI) {
- // TODO: PHI TRANSLATE.
- getNonLocalPointerDepInternal(Pointer, PointeeSize, isLoad, *PI,
- Result, Visited);
+ // 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;
}
-void MemoryDependenceAnalysis::
-getNonLocalPointerDepInternal(Value *Pointer, uint64_t PointeeSize,
- bool isLoad, BasicBlock *StartBB,
- SmallVectorImpl<NonLocalDepEntry> &Result,
- SmallPtrSet<BasicBlock*, 64> &Visited) {
- SmallVector<BasicBlock*, 32> Worklist;
- Worklist.push_back(StartBB);
+
+/// 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);
- NonLocalDepInfo *Cache = &NonLocalPointerDeps[CacheKey];
+
+ 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
// 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();
- // Analyze the dependency of *Pointer in FromBB. See if we already have
- // been here.
- if (!Visited.insert(BB))
- continue;
+ // 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.
+ // 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;
+ }
+ }
- // 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() && (&*Entry)[-1].first == BB)
- --Entry;
+ // 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;
- MemDepResult *ExistingResult = 0;
- if (Entry != Cache->begin()+NumSortedEntries && Entry->first == BB)
- ExistingResult = &Entry->second;
+ // 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 have a cached entry, and it is non-dirty, use it as the value for
- // this dependency.
- MemDepResult Dep;
- if (ExistingResult && !ExistingResult->isDirty()) {
- Dep = *ExistingResult;
- ++NumCacheNonLocalPtr;
- } else {
- // 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.
- RemoveFromReverseMap(ReverseNonLocalPtrDeps, ScanPos,
- CacheKey.getOpaqueValue());
- } else {
- ++NumUncacheNonLocalPtr;
+ // 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();
- // Scan the block for the dependency.
- 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()) {
- // 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?");
- ReverseNonLocalPtrDeps[Inst].insert(CacheKey.getOpaqueValue());
- }
+ // 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;
}
- // If we got a Def or Clobber, add this to the list of results.
- if (!Dep.isNonLocal()) {
- Result.push_back(NonLocalDepEntry(BB, Dep));
- 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;
- // Otherwise, we have to process all the predecessors of this block to scan
- // them as well.
- for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
- // TODO: PHI TRANSLATE.
- Worklist.push_back(*PI);
+ 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;
}
}
-
- // If we computed new values, re-sort Cache.
- if (NumSortedEntries != Cache->size())
+
+ // 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
// Remove all of the entries in the BB->val map. This involves removing
// instructions from the reverse map.
- NonLocalDepInfo &PInfo = It->second;
+ 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 && Target != P.getPointer());
+ assert(Target->getParent() == PInfo[i].first);
// Eliminating the dirty entry from 'Cache', so update the reverse info.
RemoveFromReverseMap(ReverseNonLocalPtrDeps, Target, P.getOpaqueValue());
}
+/// 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));
+}
+
/// 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.
assert(P.getPointer() != RemInst &&
"Already removed NonLocalPointerDeps info for RemInst");
- NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P];
+ NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P].second;
+
+ // The cache is not valid for any specific block anymore.
+ NonLocalPointerDeps[P].first = BBSkipFirstBlockPair();
// Update any entries for RemInst to use the instruction after it.
for (NonLocalDepInfo::iterator DI = NLPDI.begin(), DE = NLPDI.end();
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);
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 (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;
+ const NonLocalDepInfo &Val = I->second.second;
for (NonLocalDepInfo::const_iterator II = Val.begin(), E = Val.end();
II != E; ++II)
assert(II->second.getInst() != D && "Inst occurs as NLPD value");
projects / oota-llvm.git / blobdiff