#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/STLExtras.h"
+#include <map>
+#include <set>
using namespace llvm;
char LazyValueInfo::ID = 0;
INITIALIZE_PASS(LazyValueInfo, "lazy-value-info",
- "Lazy Value Information Analysis", false, true);
+ "Lazy Value Information Analysis", false, true)
namespace llvm {
FunctionPass *createLazyValueInfoPass() { return new LazyValueInfo(); }
Res.markNotConstant(C);
return Res;
}
+ static LVILatticeVal getRange(ConstantRange CR) {
+ LVILatticeVal Res;
+ Res.markConstantRange(CR);
+ return Res;
+ }
bool isUndefined() const { return Tag == undefined; }
bool isConstant() const { return Tag == constant; }
assert(isUndefined());
if (NewR.isEmptySet())
return markOverdefined();
- else if (NewR.isFullSet()) {
- Tag = undefined;
- return true;
- }
Tag = constantrange;
Range = NewR;
isa<ConstantExpr>(RHS.getNotConstant()))
return markOverdefined();
return false;
- }
- if (isConstant()) {
+ } else if (isConstant()) {
if (getConstant() == RHS.getNotConstant() ||
isa<ConstantExpr>(RHS.getNotConstant()) ||
isa<ConstantExpr>(getConstant()))
return markOverdefined();
return markNotConstant(RHS.getNotConstant());
+ } else if (isConstantRange()) {
+ // FIXME: This could be made more precise.
+ return markOverdefined();
}
assert(isUndefined() && "Unexpected lattice");
return markOverdefined();
else
return markConstantRange(NewR);
+ } else if (!isUndefined()) {
+ return markOverdefined();
}
assert(isUndefined() && "Unexpected lattice");
return markConstantRange(RHS.getConstantRange());
}
- // RHS must be a constant, we must be undef, constant, or notconstant.
- assert(!isConstantRange() &&
- "Constant and ConstantRange cannot be merged.");
+ // RHS must be a constant, we must be constantrange,
+ // undef, constant, or notconstant.
+ if (isConstantRange()) {
+ // FIXME: This could be made more precise.
+ return markOverdefined();
+ }
if (isUndefined())
return markConstant(RHS.getConstant());
public:
/// BlockCacheEntryTy - This is a computed lattice value at the end of the
/// specified basic block for a Value* that depends on context.
- typedef std::pair<BasicBlock*, LVILatticeVal> BlockCacheEntryTy;
+ typedef std::pair<AssertingVH<BasicBlock>, LVILatticeVal> BlockCacheEntryTy;
/// ValueCacheEntryTy - This is all of the cached block information for
/// exactly one Value*. The entries are sorted by the BasicBlock* of the
/// entries, allowing us to do a lookup with a binary search.
- typedef std::map<BasicBlock*, LVILatticeVal> ValueCacheEntryTy;
+ typedef std::map<AssertingVH<BasicBlock>, LVILatticeVal> ValueCacheEntryTy;
private:
/// LVIValueHandle - A callback value handle update the cache when
void allUsesReplacedWith(Value* V) {
deleted();
}
-
- LVIValueHandle &operator=(Value *V) {
- return *this = LVIValueHandle(V, Parent);
- }
};
/// ValueCache - This is all of the cached information for all values,
/// OverDefinedCache - This tracks, on a per-block basis, the set of
/// values that are over-defined at the end of that block. This is required
/// for cache updating.
- std::set<std::pair<BasicBlock*, Value*> > OverDefinedCache;
+ std::set<std::pair<AssertingVH<BasicBlock>, Value*> > OverDefinedCache;
public:
/// edge from PredBB to OldSucc has been threaded to be from PredBB to
/// NewSucc.
void threadEdge(BasicBlock *PredBB,BasicBlock *OldSucc,BasicBlock *NewSucc);
+
+ /// eraseBlock - This is part of the update interface to inform the cache
+ /// that a block has been deleted.
+ void eraseBlock(BasicBlock *BB);
+
+ /// clear - Empty the cache.
+ void clear() {
+ ValueCache.clear();
+ OverDefinedCache.clear();
+ }
};
} // end anonymous namespace
ValueCacheEntryTy &Cache;
/// This tracks, for each block, what values are overdefined.
- std::set<std::pair<BasicBlock*, Value*> > &OverDefinedCache;
+ std::set<std::pair<AssertingVH<BasicBlock>, Value*> > &OverDefinedCache;
/// NewBlocks - This is a mapping of the new BasicBlocks which have been
/// added to cache but that are not in sorted order.
DenseSet<BasicBlock*> NewBlockInfo;
+
public:
LVIQuery(Value *V, LazyValueInfoCache &P,
ValueCacheEntryTy &VC,
- std::set<std::pair<BasicBlock*, Value*> > &ODC)
+ std::set<std::pair<AssertingVH<BasicBlock>, Value*> > &ODC)
: Val(V), Parent(P), Cache(VC), OverDefinedCache(ODC) {
}
LVILatticeVal getEdgeValue(BasicBlock *FromBB, BasicBlock *ToBB);
private:
- LVILatticeVal &getCachedEntryForBlock(BasicBlock *BB);
+ LVILatticeVal getCachedEntryForBlock(BasicBlock *BB);
};
} // end anonymous namespace
void LazyValueInfoCache::LVIValueHandle::deleted() {
- Parent->ValueCache.erase(*this);
- for (std::set<std::pair<BasicBlock*, Value*> >::iterator
+ for (std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator
I = Parent->OverDefinedCache.begin(),
E = Parent->OverDefinedCache.end();
I != E; ) {
- std::set<std::pair<BasicBlock*, Value*> >::iterator tmp = I;
+ std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator tmp = I;
++I;
if (tmp->second == getValPtr())
Parent->OverDefinedCache.erase(tmp);
}
+
+ // This erasure deallocates *this, so it MUST happen after we're done
+ // using any and all members of *this.
+ Parent->ValueCache.erase(*this);
}
+void LazyValueInfoCache::eraseBlock(BasicBlock *BB) {
+ for (std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator
+ I = OverDefinedCache.begin(), E = OverDefinedCache.end(); I != E; ) {
+ std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator tmp = I;
+ ++I;
+ if (tmp->first == BB)
+ OverDefinedCache.erase(tmp);
+ }
+
+ for (std::map<LVIValueHandle, ValueCacheEntryTy>::iterator
+ I = ValueCache.begin(), E = ValueCache.end(); I != E; ++I)
+ I->second.erase(BB);
+}
/// getCachedEntryForBlock - See if we already have a value for this block. If
/// so, return it, otherwise create a new entry in the Cache map to use.
-LVILatticeVal &LVIQuery::getCachedEntryForBlock(BasicBlock *BB) {
+LVILatticeVal LVIQuery::getCachedEntryForBlock(BasicBlock *BB) {
NewBlockInfo.insert(BB);
return Cache[BB];
}
LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
// See if we already have a value for this block.
- LVILatticeVal &BBLV = getCachedEntryForBlock(BB);
+ LVILatticeVal BBLV = getCachedEntryForBlock(BB);
// If we've already computed this block's value, return it.
if (!BBLV.isUndefined()) {
// lattice value to overdefined, so that cycles will terminate and be
// conservatively correct.
BBLV.markOverdefined();
+ Cache[BB] = BBLV;
- // If V is live into BB, see if our predecessors know anything about it.
Instruction *BBI = dyn_cast<Instruction>(Val);
if (BBI == 0 || BBI->getParent() != BB) {
LVILatticeVal Result; // Start Undefined.
- unsigned NumPreds = 0;
+ // If this is a pointer, and there's a load from that pointer in this BB,
+ // then we know that the pointer can't be NULL.
+ bool NotNull = false;
+ if (Val->getType()->isPointerTy()) {
+ for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();BI != BE;++BI){
+ LoadInst *L = dyn_cast<LoadInst>(BI);
+ if (L && L->getPointerAddressSpace() == 0 &&
+ L->getPointerOperand()->getUnderlyingObject() ==
+ Val->getUnderlyingObject()) {
+ NotNull = true;
+ break;
+ }
+ }
+ }
+
+ unsigned NumPreds = 0;
// Loop over all of our predecessors, merging what we know from them into
// result.
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
if (Result.isOverdefined()) {
DEBUG(dbgs() << " compute BB '" << BB->getName()
<< "' - overdefined because of pred.\n");
+ // If we previously determined that this is a pointer that can't be null
+ // then return that rather than giving up entirely.
+ if (NotNull) {
+ const PointerType *PTy = cast<PointerType>(Val->getType());
+ Result = LVILatticeVal::getNot(ConstantPointerNull::get(PTy));
+ }
+
return Result;
}
++NumPreds;
}
+
// If this is the entry block, we must be asking about an argument. The
// value is overdefined.
if (NumPreds == 0 && BB == &BB->getParent()->front()) {
// Return the merged value, which is more precise than 'overdefined'.
assert(!Result.isOverdefined());
- return getCachedEntryForBlock(BB) = Result;
+ return Cache[BB] = Result;
}
// If this value is defined by an instruction in this block, we have to
// Return the merged value, which is more precise than 'overdefined'.
assert(!Result.isOverdefined());
- return getCachedEntryForBlock(BB) = Result;
+ return Cache[BB] = Result;
+ }
- } else {
+ assert(Cache[BB].isOverdefined() && "Recursive query changed our cache?");
+
+ // We can only analyze the definitions of certain classes of instructions
+ // (integral binops and casts at the moment), so bail if this isn't one.
+ LVILatticeVal Result;
+ if ((!isa<BinaryOperator>(BBI) && !isa<CastInst>(BBI)) ||
+ !BBI->getType()->isIntegerTy()) {
+ DEBUG(dbgs() << " compute BB '" << BB->getName()
+ << "' - overdefined because inst def found.\n");
+ Result.markOverdefined();
+ return Result;
+ }
+
+ // FIXME: We're currently limited to binops with a constant RHS. This should
+ // be improved.
+ BinaryOperator *BO = dyn_cast<BinaryOperator>(BBI);
+ if (BO && !isa<ConstantInt>(BO->getOperand(1))) {
+ DEBUG(dbgs() << " compute BB '" << BB->getName()
+ << "' - overdefined because inst def found.\n");
+
+ Result.markOverdefined();
+ return Result;
+ }
+
+ // Figure out the range of the LHS. If that fails, bail.
+ LVILatticeVal LHSVal = Parent.getValueInBlock(BBI->getOperand(0), BB);
+ if (!LHSVal.isConstantRange()) {
+ Result.markOverdefined();
+ return Result;
+ }
+
+ ConstantInt *RHS = 0;
+ ConstantRange LHSRange = LHSVal.getConstantRange();
+ ConstantRange RHSRange(1);
+ const IntegerType *ResultTy = cast<IntegerType>(BBI->getType());
+ if (isa<BinaryOperator>(BBI)) {
+ RHS = dyn_cast<ConstantInt>(BBI->getOperand(1));
+ if (!RHS) {
+ Result.markOverdefined();
+ return Result;
+ }
+ RHSRange = ConstantRange(RHS->getValue(), RHS->getValue()+1);
+ }
+
+ // NOTE: We're currently limited by the set of operations that ConstantRange
+ // can evaluate symbolically. Enhancing that set will allows us to analyze
+ // more definitions.
+ switch (BBI->getOpcode()) {
+ case Instruction::Add:
+ Result.markConstantRange(LHSRange.add(RHSRange));
+ break;
+ case Instruction::Sub:
+ Result.markConstantRange(LHSRange.sub(RHSRange));
+ break;
+ case Instruction::Mul:
+ Result.markConstantRange(LHSRange.multiply(RHSRange));
+ break;
+ case Instruction::UDiv:
+ Result.markConstantRange(LHSRange.udiv(RHSRange));
+ break;
+ case Instruction::Shl:
+ Result.markConstantRange(LHSRange.shl(RHSRange));
+ break;
+ case Instruction::LShr:
+ Result.markConstantRange(LHSRange.lshr(RHSRange));
+ break;
+ case Instruction::Trunc:
+ Result.markConstantRange(LHSRange.truncate(ResultTy->getBitWidth()));
+ break;
+ case Instruction::SExt:
+ Result.markConstantRange(LHSRange.signExtend(ResultTy->getBitWidth()));
+ break;
+ case Instruction::ZExt:
+ Result.markConstantRange(LHSRange.zeroExtend(ResultTy->getBitWidth()));
+ break;
+ case Instruction::BitCast:
+ Result.markConstantRange(LHSRange);
+ break;
+ case Instruction::And:
+ Result.markConstantRange(LHSRange.binaryAnd(RHSRange));
+ break;
+ case Instruction::Or:
+ Result.markConstantRange(LHSRange.binaryOr(RHSRange));
+ break;
+
+ // Unhandled instructions are overdefined.
+ default:
+ DEBUG(dbgs() << " compute BB '" << BB->getName()
+ << "' - overdefined because inst def found.\n");
+ Result.markOverdefined();
+ break;
}
- DEBUG(dbgs() << " compute BB '" << BB->getName()
- << "' - overdefined because inst def found.\n");
-
- LVILatticeVal Result;
- Result.markOverdefined();
- return getCachedEntryForBlock(BB) = Result;
+ return Cache[BB] = Result;
}
// If the condition of the branch is an equality comparison, we may be
// able to infer the value.
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition()))
- if (ICI->isEquality() && ICI->getOperand(0) == Val &&
- isa<Constant>(ICI->getOperand(1))) {
+ ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition());
+ if (ICI && ICI->getOperand(0) == Val &&
+ isa<Constant>(ICI->getOperand(1))) {
+ if (ICI->isEquality()) {
// We know that V has the RHS constant if this is a true SETEQ or
// false SETNE.
if (isTrueDest == (ICI->getPredicate() == ICmpInst::ICMP_EQ))
return LVILatticeVal::get(cast<Constant>(ICI->getOperand(1)));
return LVILatticeVal::getNot(cast<Constant>(ICI->getOperand(1)));
}
+
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
+ // Calculate the range of values that would satisfy the comparison.
+ ConstantRange CmpRange(CI->getValue(), CI->getValue()+1);
+ ConstantRange TrueValues =
+ ConstantRange::makeICmpRegion(ICI->getPredicate(), CmpRange);
+
+ // If we're interested in the false dest, invert the condition.
+ if (!isTrueDest) TrueValues = TrueValues.inverse();
+
+ // Figure out the possible values of the query BEFORE this branch.
+ LVILatticeVal InBlock = getBlockValue(BBFrom);
+ if (!InBlock.isConstantRange())
+ return LVILatticeVal::getRange(TrueValues);
+
+ // Find all potential values that satisfy both the input and output
+ // conditions.
+ ConstantRange PossibleValues =
+ TrueValues.intersectWith(InBlock.getConstantRange());
+
+ return LVILatticeVal::getRange(PossibleValues);
+ }
+ }
}
}
// If the edge was formed by a switch on the value, then we may know exactly
// what it is.
if (SwitchInst *SI = dyn_cast<SwitchInst>(BBFrom->getTerminator())) {
- // If BBTo is the default destination of the switch, we don't know anything.
- // Given a more powerful range analysis we could know stuff.
- if (SI->getCondition() == Val && SI->getDefaultDest() != BBTo) {
+ if (SI->getCondition() == Val) {
+ // We don't know anything in the default case.
+ if (SI->getDefaultDest() == BBTo) {
+ LVILatticeVal Result;
+ Result.markOverdefined();
+ return Result;
+ }
+
// We only know something if there is exactly one value that goes from
// BBFrom to BBTo.
unsigned NumEdges = 0;
<< BB->getName() << "'\n");
LVILatticeVal Result = LVIQuery(V, *this,
- ValueCache[LVIValueHandle(V, this)],
- OverDefinedCache).getBlockValue(BB);
+ ValueCache[LVIValueHandle(V, this)],
+ OverDefinedCache).getBlockValue(BB);
DEBUG(dbgs() << " Result = " << Result << "\n");
return Result;
worklist.push_back(OldSucc);
DenseSet<Value*> ClearSet;
- for (std::set<std::pair<BasicBlock*, Value*> >::iterator
+ for (std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator
I = OverDefinedCache.begin(), E = OverDefinedCache.end(); I != E; ++I) {
if (I->first == OldSucc)
ClearSet.insert(I->second);
for (DenseSet<Value*>::iterator I = ClearSet.begin(),E = ClearSet.end();
I != E; ++I) {
// If a value was marked overdefined in OldSucc, and is here too...
- std::set<std::pair<BasicBlock*, Value*> >::iterator OI =
+ std::set<std::pair<AssertingVH<BasicBlock>, Value*> >::iterator OI =
OverDefinedCache.find(std::make_pair(ToUpdate, *I));
if (OI == OverDefinedCache.end()) continue;
// LazyValueInfo Impl
//===----------------------------------------------------------------------===//
-bool LazyValueInfo::runOnFunction(Function &F) {
- TD = getAnalysisIfAvailable<TargetData>();
- // Fully lazy.
- return false;
-}
-
/// getCache - This lazily constructs the LazyValueInfoCache.
static LazyValueInfoCache &getCache(void *&PImpl) {
if (!PImpl)
return *static_cast<LazyValueInfoCache*>(PImpl);
}
+bool LazyValueInfo::runOnFunction(Function &F) {
+ if (PImpl)
+ getCache(PImpl).clear();
+
+ TD = getAnalysisIfAvailable<TargetData>();
+ // Fully lazy.
+ return false;
+}
+
void LazyValueInfo::releaseMemory() {
// If the cache was allocated, free it.
if (PImpl) {
if (Result.isConstant())
return Result.getConstant();
+ else if (Result.isConstantRange()) {
+ ConstantRange CR = Result.getConstantRange();
+ if (const APInt *SingleVal = CR.getSingleElement())
+ return ConstantInt::get(V->getContext(), *SingleVal);
+ }
return 0;
}
}
if (Result.isConstantRange()) {
- ConstantInt *CI = cast<ConstantInt>(C);
+ ConstantInt *CI = dyn_cast<ConstantInt>(C);
+ if (!CI) return Unknown;
+
ConstantRange CR = Result.getConstantRange();
if (Pred == ICmpInst::ICMP_EQ) {
if (!CR.contains(CI->getValue()))
ConstantRange TrueValues = ConstantRange::makeICmpRegion(Pred, RHS);
if (CR.intersectWith(TrueValues).isEmptySet())
return False;
- else if (CR.intersectWith(TrueValues) == CR)
+ else if (TrueValues.contains(CR))
return True;
return Unknown;
void LazyValueInfo::threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc,
BasicBlock* NewSucc) {
- getCache(PImpl).threadEdge(PredBB, OldSucc, NewSucc);
+ if (PImpl) getCache(PImpl).threadEdge(PredBB, OldSucc, NewSucc);
+}
+
+void LazyValueInfo::eraseBlock(BasicBlock *BB) {
+ if (PImpl) getCache(PImpl).eraseBlock(BB);
}
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