-//===- LazyValueInfo.cpp - Value constraint analysis ----------------------===//
+//===- LazyValueInfo.cpp - Value constraint analysis ------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
/// recursive value lookup process.
std::stack<std::pair<BasicBlock*, Value*> > BlockValueStack;
+ /// BlockValueSet - Keeps track of which block-value pairs are in
+ /// BlockValueStack.
+ DenseSet<std::pair<BasicBlock*, Value*> > BlockValueSet;
+
+ /// pushBlockValue - Push BV onto BlockValueStack unless it's already in
+ /// there. Returns true on success.
+ bool pushBlockValue(const std::pair<BasicBlock *, Value *> &BV) {
+ if (BlockValueSet.count(BV))
+ return false; // It's already in the stack.
+
+ BlockValueStack.push(BV);
+ BlockValueSet.insert(BV);
+ return true;
+ }
+
/// A pointer to the cache of @llvm.assume calls.
AssumptionTracker *AT;
/// An optional DL pointer.
DominatorTree *DT;
friend struct LVIValueHandle;
-
- /// OverDefinedCacheUpdater - A helper object that ensures that the
- /// OverDefinedCache is updated whenever solveBlockValue returns.
- struct OverDefinedCacheUpdater {
- LazyValueInfoCache *Parent;
- Value *Val;
- BasicBlock *BB;
- LVILatticeVal &BBLV;
-
- OverDefinedCacheUpdater(Value *V, BasicBlock *B, LVILatticeVal &LV,
- LazyValueInfoCache *P)
- : Parent(P), Val(V), BB(B), BBLV(LV) { }
-
- bool markResult(bool changed) {
- if (changed && BBLV.isOverdefined())
- Parent->OverDefinedCache.insert(std::make_pair(BB, Val));
- return changed;
- }
- };
-
+ void insertResult(Value *Val, BasicBlock *BB, const LVILatticeVal &Result) {
+ SeenBlocks.insert(BB);
+ lookup(Val)[BB] = Result;
+ if (Result.isOverdefined())
+ OverDefinedCache.insert(std::make_pair(BB, Val));
+ }
LVILatticeVal getBlockValue(Value *Val, BasicBlock *BB);
bool getEdgeValue(Value *V, BasicBlock *F, BasicBlock *T,
typedef std::pair<AssertingVH<BasicBlock>, Value*> OverDefinedPairTy;
SmallVector<OverDefinedPairTy, 4> ToErase;
- for (DenseSet<OverDefinedPairTy>::iterator
- I = Parent->OverDefinedCache.begin(),
- E = Parent->OverDefinedCache.end();
- I != E; ++I) {
- if (I->second == getValPtr())
- ToErase.push_back(*I);
- }
-
- for (SmallVectorImpl<OverDefinedPairTy>::iterator I = ToErase.begin(),
- E = ToErase.end(); I != E; ++I)
- Parent->OverDefinedCache.erase(*I);
+ for (const OverDefinedPairTy &P : Parent->OverDefinedCache)
+ if (P.second == getValPtr())
+ ToErase.push_back(P);
+ for (const OverDefinedPairTy &P : ToErase)
+ Parent->OverDefinedCache.erase(P);
// This erasure deallocates *this, so it MUST happen after we're done
// using any and all members of *this.
SeenBlocks.erase(I);
SmallVector<OverDefinedPairTy, 4> ToErase;
- for (DenseSet<OverDefinedPairTy>::iterator I = OverDefinedCache.begin(),
- E = OverDefinedCache.end(); I != E; ++I) {
- if (I->first == BB)
- ToErase.push_back(*I);
- }
-
- for (SmallVectorImpl<OverDefinedPairTy>::iterator I = ToErase.begin(),
- E = ToErase.end(); I != E; ++I)
- OverDefinedCache.erase(*I);
+ for (const OverDefinedPairTy& P : OverDefinedCache)
+ if (P.first == BB)
+ ToErase.push_back(P);
+ for (const OverDefinedPairTy &P : ToErase)
+ OverDefinedCache.erase(P);
for (std::map<LVIValueHandle, ValueCacheEntryTy>::iterator
I = ValueCache.begin(), E = ValueCache.end(); I != E; ++I)
void LazyValueInfoCache::solve() {
while (!BlockValueStack.empty()) {
std::pair<BasicBlock*, Value*> &e = BlockValueStack.top();
+ assert(BlockValueSet.count(e) && "Stack value should be in BlockValueSet!");
+
if (solveBlockValue(e.second, e.first)) {
- assert(BlockValueStack.top() == e);
+ // The work item was completely processed.
+ assert(BlockValueStack.top() == e && "Nothing should have been pushed!");
+ assert(lookup(e.second).count(e.first) && "Result should be in cache!");
+
BlockValueStack.pop();
+ BlockValueSet.erase(e);
+ } else {
+ // More work needs to be done before revisiting.
+ assert(BlockValueStack.top() != e && "Stack should have been pushed!");
}
}
}
if (isa<Constant>(Val))
return true;
- ValueCacheEntryTy &Cache = lookup(Val);
- SeenBlocks.insert(BB);
- LVILatticeVal &BBLV = Cache[BB];
-
- // OverDefinedCacheUpdater is a helper object that will update
- // the OverDefinedCache for us when this method exits. Make sure to
- // call markResult on it as we exist, passing a bool to indicate if the
- // cache needs updating, i.e. if we have solve a new value or not.
- OverDefinedCacheUpdater ODCacheUpdater(Val, BB, BBLV, this);
-
- if (!BBLV.isUndefined()) {
- DEBUG(dbgs() << " reuse BB '" << BB->getName() << "' val=" << BBLV <<'\n');
-
- // Since we're reusing a cached value here, we don't need to update the
- // OverDefinedCahce. The cache will have been properly updated
- // whenever the cached value was inserted.
- ODCacheUpdater.markResult(false);
+ if (lookup(Val).count(BB)) {
+ // If we have a cached value, use that.
+ DEBUG(dbgs() << " reuse BB '" << BB->getName()
+ << "' val=" << lookup(Val)[BB] << '\n');
+
+ // Since we're reusing a cached value, we don't need to update the
+ // OverDefinedCache. The cache will have been properly updated whenever the
+ // cached value was inserted.
return true;
}
- // Otherwise, this is the first time we're seeing this block. Reset the
- // lattice value to overdefined, so that cycles will terminate and be
- // conservatively correct.
- BBLV.markOverdefined();
+ // Hold off inserting this value into the Cache in case we have to return
+ // false and come back later.
+ LVILatticeVal Res;
Instruction *BBI = dyn_cast<Instruction>(Val);
if (!BBI || BBI->getParent() != BB) {
- return ODCacheUpdater.markResult(solveBlockValueNonLocal(BBLV, Val, BB));
+ if (!solveBlockValueNonLocal(Res, Val, BB))
+ return false;
+ insertResult(Val, BB, Res);
+ return true;
}
if (PHINode *PN = dyn_cast<PHINode>(BBI)) {
- return ODCacheUpdater.markResult(solveBlockValuePHINode(BBLV, PN, BB));
+ if (!solveBlockValuePHINode(Res, PN, BB))
+ return false;
+ insertResult(Val, BB, Res);
+ return true;
}
if (AllocaInst *AI = dyn_cast<AllocaInst>(BBI)) {
- BBLV = LVILatticeVal::getNot(ConstantPointerNull::get(AI->getType()));
- return ODCacheUpdater.markResult(true);
+ Res = LVILatticeVal::getNot(ConstantPointerNull::get(AI->getType()));
+ insertResult(Val, BB, Res);
+ return true;
}
// We can only analyze the definitions of certain classes of instructions
!BBI->getType()->isIntegerTy()) {
DEBUG(dbgs() << " compute BB '" << BB->getName()
<< "' - overdefined because inst def found.\n");
- BBLV.markOverdefined();
- return ODCacheUpdater.markResult(true);
+ Res.markOverdefined();
+ insertResult(Val, BB, Res);
+ return true;
}
// FIXME: We're currently limited to binops with a constant RHS. This should
DEBUG(dbgs() << " compute BB '" << BB->getName()
<< "' - overdefined because inst def found.\n");
- BBLV.markOverdefined();
- return ODCacheUpdater.markResult(true);
+ Res.markOverdefined();
+ insertResult(Val, BB, Res);
+ return true;
}
- return ODCacheUpdater.markResult(solveBlockValueConstantRange(BBLV, BBI, BB));
+ if (!solveBlockValueConstantRange(Res, BBI, BB))
+ return false;
+ insertResult(Val, BB, Res);
+ return true;
}
static bool InstructionDereferencesPointer(Instruction *I, Value *Ptr) {
// If 'GetUnderlyingObject' didn't converge, skip it. It won't converge
// inside InstructionDereferencesPointer either.
if (UnderlyingVal == GetUnderlyingObject(UnderlyingVal, nullptr, 1)) {
- for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
- BI != BE; ++BI) {
- if (InstructionDereferencesPointer(BI, UnderlyingVal)) {
+ for (Instruction &I : *BB) {
+ if (InstructionDereferencesPointer(&I, UnderlyingVal)) {
NotNull = true;
break;
}
BasicBlock *PhiBB = PN->getIncomingBlock(i);
Value *PhiVal = PN->getIncomingValue(i);
LVILatticeVal EdgeResult;
+ // Note that we can provide PN as the context value to getEdgeValue, even
+ // though the results will be cached, because PN is the value being used as
+ // the cache key in the caller.
EdgesMissing |= !getEdgeValue(PhiVal, PhiBB, BB, EdgeResult, PN);
if (EdgesMissing)
continue;
LVILatticeVal &Result,
bool isTrueDest = true);
-// If we can determine a constant range for the value Val at the context
+// If we can determine a constant range for the value Val in the context
// provided by the instruction BBI, then merge it into BBLV. If we did find a
// constant range, return true.
-void LazyValueInfoCache::mergeAssumeBlockValueConstantRange(
- Value *Val, LVILatticeVal &BBLV, Instruction *BBI) {
+void LazyValueInfoCache::mergeAssumeBlockValueConstantRange(Value *Val,
+ LVILatticeVal &BBLV,
+ Instruction *BBI) {
BBI = BBI ? BBI : dyn_cast<Instruction>(Val);
if (!BBI)
return;
BasicBlock *BB) {
// Figure out the range of the LHS. If that fails, bail.
if (!hasBlockValue(BBI->getOperand(0), BB)) {
- BlockValueStack.push(std::make_pair(BB, BBI->getOperand(0)));
- return false;
+ if (pushBlockValue(std::make_pair(BB, BBI->getOperand(0))))
+ return false;
+ BBLV.markOverdefined();
+ return true;
}
LVILatticeVal LHSVal = getBlockValue(BBI->getOperand(0), BB);
unsigned BitWidth = Val->getType()->getIntegerBitWidth();
ConstantRange EdgesVals(BitWidth, DefaultCase/*isFullSet*/);
- for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
- i != e; ++i) {
+ for (SwitchInst::CaseIt i : SI->cases()) {
ConstantRange EdgeVal(i.getCaseValue()->getValue());
if (DefaultCase) {
// It is possible that the default destination is the destination of
if (getEdgeValueLocal(Val, BBFrom, BBTo, Result)) {
if (!Result.isConstantRange() ||
- Result.getConstantRange().getSingleElement())
+ Result.getConstantRange().getSingleElement())
return true;
// FIXME: this check should be moved to the beginning of the function when
// LVI better supports recursive values. Even for the single value case, we
// can intersect to detect dead code (an empty range).
if (!hasBlockValue(Val, BBFrom)) {
- BlockValueStack.push(std::make_pair(BBFrom, Val));
- return false;
+ if (pushBlockValue(std::make_pair(BBFrom, Val)))
+ return false;
+ Result.markOverdefined();
+ return true;
}
// Try to intersect ranges of the BB and the constraint on the edge.
LVILatticeVal InBlock = getBlockValue(Val, BBFrom);
mergeAssumeBlockValueConstantRange(Val, InBlock, BBFrom->getTerminator());
+ // See note on the use of the CxtI with mergeAssumeBlockValueConstantRange,
+ // and caching, below.
mergeAssumeBlockValueConstantRange(Val, InBlock, CxtI);
if (!InBlock.isConstantRange())
return true;
}
if (!hasBlockValue(Val, BBFrom)) {
- BlockValueStack.push(std::make_pair(BBFrom, Val));
- return false;
+ if (pushBlockValue(std::make_pair(BBFrom, Val)))
+ return false;
+ Result.markOverdefined();
+ return true;
}
- // if we couldn't compute the value on the edge, use the value from the BB
+ // If we couldn't compute the value on the edge, use the value from the BB.
Result = getBlockValue(Val, BBFrom);
mergeAssumeBlockValueConstantRange(Val, Result, BBFrom->getTerminator());
+ // We can use the context instruction (generically the ultimate instruction
+ // the calling pass is trying to simplify) here, even though the result of
+ // this function is generally cached when called from the solve* functions
+ // (and that cached result might be used with queries using a different
+ // context instruction), because when this function is called from the solve*
+ // functions, the context instruction is not provided. When called from
+ // LazyValueInfoCache::getValueOnEdge, the context instruction is provided,
+ // but then the result is not cached.
mergeAssumeBlockValueConstantRange(Val, Result, CxtI);
return true;
}
DEBUG(dbgs() << "LVI Getting block end value " << *V << " at '"
<< BB->getName() << "'\n");
- BlockValueStack.push(std::make_pair(BB, V));
+ assert(BlockValueStack.empty() && BlockValueSet.empty());
+ pushBlockValue(std::make_pair(BB, V));
+
solve();
LVILatticeVal Result = getBlockValue(V, BB);
mergeAssumeBlockValueConstantRange(V, Result, CxtI);
// we clear their entries from the cache, and allow lazy updating to recompute
// them when needed.
- // The updating process is fairly simple: we need to dropped cached info
+ // The updating process is fairly simple: we need to drop cached info
// for all values that were marked overdefined in OldSucc, and for those same
// values in any successor of OldSucc (except NewSucc) in which they were
// also marked overdefined.
worklist.push_back(OldSucc);
DenseSet<Value*> ClearSet;
- for (DenseSet<OverDefinedPairTy>::iterator I = OverDefinedCache.begin(),
- E = OverDefinedCache.end(); I != E; ++I) {
- if (I->first == OldSucc)
- ClearSet.insert(I->second);
- }
+ for (OverDefinedPairTy &P : OverDefinedCache)
+ if (P.first == OldSucc)
+ ClearSet.insert(P.second);
// Use a worklist to perform a depth-first search of OldSucc's successors.
// NOTE: We do not need a visited list since any blocks we have already
if (ToUpdate == NewSucc) continue;
bool changed = false;
- for (DenseSet<Value*>::iterator I = ClearSet.begin(), E = ClearSet.end();
- I != E; ++I) {
+ for (Value *V : ClearSet) {
// If a value was marked overdefined in OldSucc, and is here too...
DenseSet<OverDefinedPairTy>::iterator OI =
- OverDefinedCache.find(std::make_pair(ToUpdate, *I));
+ OverDefinedCache.find(std::make_pair(ToUpdate, V));
if (OI == OverDefinedCache.end()) continue;
// Remove it from the caches.
- ValueCacheEntryTy &Entry = ValueCache[LVIValueHandle(*I, this)];
+ ValueCacheEntryTy &Entry = ValueCache[LVIValueHandle(V, this)];
ValueCacheEntryTy::iterator CI = Entry.find(ToUpdate);
assert(CI != Entry.end() && "Couldn't find entry to update?");
DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
DL = DLP ? &DLP->getDataLayout() : nullptr;
+
TLI = &getAnalysis<TargetLibraryInfo>();
if (PImpl)
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