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refactor a bunch of code forming the new LazyValueInfoCache

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and LVIQuery classes, no functionality change.

llvm-svn: 88866
This commit is contained in:
Chris Lattner 2009-11-15 19:59:49 +00:00
parent 15cd19dddb
commit b9a9336376
1 changed files with 190 additions and 112 deletions
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302
lib/Analysis/LazyValueInfo.cpp
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@ -195,28 +195,132 @@ raw_ostream &operator<<(raw_ostream &OS, const LVILatticeVal &Val) {
}
//===----------------------------------------------------------------------===//
// LazyValueInfo Impl
// LazyValueInfoCache Decl
//===----------------------------------------------------------------------===//
bool LazyValueInfo::runOnFunction(Function &F) {
TD = getAnalysisIfAvailable<TargetData>();
// Fully lazy.
return false;
namespace {
/// LazyValueInfoCache - This is the cache kept by LazyValueInfo which
/// maintains information about queries across the clients' queries.
class LazyValueInfoCache {
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;
/// 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::vector<BlockCacheEntryTy> ValueCacheEntryTy;
private:
/// ValueCache - This is all of the cached information for all values,
/// mapped from Value* to key information.
DenseMap<Value*, ValueCacheEntryTy> ValueCache;
public:
/// getValueInBlock - This is the query interface to determine the lattice
/// value for the specified Value* at the end of the specified block.
LVILatticeVal getValueInBlock(Value *V, BasicBlock *BB);
/// getValueOnEdge - This is the query interface to determine the lattice
/// value for the specified Value* that is true on the specified edge.
LVILatticeVal getValueOnEdge(Value *V, BasicBlock *FromBB,BasicBlock *ToBB);
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// LVIQuery Impl
//===----------------------------------------------------------------------===//
namespace {
/// LVIQuery - This is a transient object that exists while a query is
/// being performed.
class LVIQuery {
typedef LazyValueInfoCache::BlockCacheEntryTy BlockCacheEntryTy;
typedef LazyValueInfoCache::ValueCacheEntryTy ValueCacheEntryTy;
/// This is the current value being queried.
Value *Val;
/// This is all of the cached information about this value.
ValueCacheEntryTy &Cache;
/// BlockVals Temporary Cache used while processing a query.
DenseMap<BasicBlock*, LVILatticeVal> BlockVals;
public:
LVIQuery(Value *V, ValueCacheEntryTy &VC) : Val(V), Cache(VC) {
}
LVILatticeVal getBlockValue(BasicBlock *BB);
LVILatticeVal getEdgeValue(BasicBlock *FromBB, BasicBlock *ToBB);
};
} // end anonymous namespace
LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
// See if we already have a value for this block.
LVILatticeVal &BBLV = BlockVals[BB];
// If we've already computed this block's value, return it.
if (!BBLV.isUndefined())
return BBLV;
// 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();
// 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;
// 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) {
Result.mergeIn(getEdgeValue(*PI, BB));
// If we hit overdefined, exit early. The BlockVals entry is already set
// to overdefined.
if (Result.isOverdefined())
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()) {
assert(isa<Argument>(Val) && "Unknown live-in to the entry block");
Result.markOverdefined();
return Result;
}
// Return the merged value, which is more precise than 'overdefined'.
assert(!Result.isOverdefined());
return BlockVals[BB] = Result;
}
// If this value is defined by an instruction in this block, we have to
// process it here somehow or return overdefined.
if (PHINode *PN = dyn_cast<PHINode>(BBI)) {
(void)PN;
// TODO: PHI Translation in preds.
} else {
}
LVILatticeVal Result;
Result.markOverdefined();
return BlockVals[BB] = Result;
}
void LazyValueInfo::releaseMemory() {
// No caching yet.
}
static LVILatticeVal GetValueInBlock(Value *V, BasicBlock *BB,
DenseMap<BasicBlock*, LVILatticeVal> &);
static LVILatticeVal GetValueOnEdge(Value *V, BasicBlock *BBFrom,
BasicBlock *BBTo,
DenseMap<BasicBlock*, LVILatticeVal> &BlockVals) {
// FIXME: Pull edge logic out of jump threading.
/// getEdgeValue - This method
LVILatticeVal LVIQuery::getEdgeValue(BasicBlock *BBFrom, BasicBlock *BBTo) {
if (BranchInst *BI = dyn_cast<BranchInst>(BBFrom->getTerminator())) {
// If this is a conditional branch and only one successor goes to BBTo, then
// we maybe able to infer something from the condition.
@ -228,14 +332,14 @@ static LVILatticeVal GetValueOnEdge(Value *V, BasicBlock *BBFrom,
// If V is the condition of the branch itself, then we know exactly what
// it is.
if (BI->getCondition() == V)
if (BI->getCondition() == Val)
return LVILatticeVal::get(ConstantInt::get(
Type::getInt1Ty(V->getContext()), isTrueDest));
Type::getInt1Ty(Val->getContext()), isTrueDest));
// 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) == V &&
if (ICI->isEquality() && ICI->getOperand(0) == Val &&
isa<Constant>(ICI->getOperand(1))) {
// We know that V has the RHS constant if this is a true SETEQ or
// false SETNE.
@ -248,84 +352,76 @@ static LVILatticeVal GetValueOnEdge(Value *V, BasicBlock *BBFrom,
// TODO: Info from switch.
// TODO: Handle more complex conditionals. If (v == 0 || v2 < 1) is false, we
// know that v != 0.
// Otherwise see if the value is known in the block.
return GetValueInBlock(V, BBFrom, BlockVals);
}
static LVILatticeVal GetValueInBlock(Value *V, BasicBlock *BB,
DenseMap<BasicBlock*, LVILatticeVal> &BlockVals) {
// See if we already have a value for this block.
LVILatticeVal &BBLV = BlockVals[BB];
// If we've already computed this block's value, return it.
if (!BBLV.isUndefined())
return BBLV;
// 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();
LVILatticeVal Result; // Start Undefined.
// If V is live in to BB, see if our predecessors know anything about it.
Instruction *BBI = dyn_cast<Instruction>(V);
if (BBI == 0 || BBI->getParent() != BB) {
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) {
Result.mergeIn(GetValueOnEdge(V, *PI, BB, BlockVals));
// If we hit overdefined, exit early. The BlockVals entry is already set
// to overdefined.
if (Result.isOverdefined())
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()) {
assert(isa<Argument>(V) && "Unknown live-in to the entry block");
Result.markOverdefined();
return Result;
}
// Return the merged value, which is more precise than 'overdefined'.
assert(!Result.isOverdefined());
return BlockVals[BB] = Result;
}
// If this value is defined by an instruction in this block, we have to
// process it here somehow or return overdefined.
if (PHINode *PN = dyn_cast<PHINode>(BBI)) {
(void)PN;
// TODO: PHI Translation in preds.
} else {
}
Result.markOverdefined();
return BlockVals[BB] = Result;
return getBlockValue(BBFrom);
}
Constant *LazyValueInfo::getConstant(Value *V, BasicBlock *BB) {
// If already a constant, return it.
//===----------------------------------------------------------------------===//
// LazyValueInfoCache Impl
//===----------------------------------------------------------------------===//
LVILatticeVal LazyValueInfoCache::getValueInBlock(Value *V, BasicBlock *BB) {
// If already a constant, there is nothing to compute.
if (Constant *VC = dyn_cast<Constant>(V))
return VC;
DenseMap<BasicBlock*, LVILatticeVal> BlockValues;
return LVILatticeVal::get(VC);
DEBUG(errs() << "Getting value " << *V << " at end of block '"
<< BB->getName() << "'\n");
LVILatticeVal Result = GetValueInBlock(V, BB, BlockValues);
<< BB->getName() << "'\n");
LVILatticeVal Result = LVIQuery(V, ValueCache[V]).getBlockValue(BB);
DEBUG(errs() << " Result = " << Result << "\n");
return Result;
}
LVILatticeVal LazyValueInfoCache::
getValueOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB) {
// If already a constant, there is nothing to compute.
if (Constant *VC = dyn_cast<Constant>(V))
return LVILatticeVal::get(VC);
DEBUG(errs() << "Getting value " << *V << " on edge from '"
<< FromBB->getName() << "' to '" << ToBB->getName() << "'\n");
LVILatticeVal Result =
LVIQuery(V, ValueCache[V]).getEdgeValue(FromBB, ToBB);
DEBUG(errs() << " Result = " << Result << "\n");
return Result;
}
//===----------------------------------------------------------------------===//
// 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)
PImpl = new LazyValueInfoCache();
return *static_cast<LazyValueInfoCache*>(PImpl);
}
void LazyValueInfo::releaseMemory() {
// If the cache was allocated, free it.
if (PImpl) {
delete &getCache(PImpl);
PImpl = 0;
}
}
Constant *LazyValueInfo::getConstant(Value *V, BasicBlock *BB) {
LVILatticeVal Result = getCache(PImpl).getValueInBlock(V, BB);
if (Result.isConstant())
return Result.getConstant();
return 0;
@ -335,17 +431,7 @@ Constant *LazyValueInfo::getConstant(Value *V, BasicBlock *BB) {
/// constant on the specified edge. Return null if not.
Constant *LazyValueInfo::getConstantOnEdge(Value *V, BasicBlock *FromBB,
BasicBlock *ToBB) {
// If already a constant, return it.
if (Constant *VC = dyn_cast<Constant>(V))
return VC;
DenseMap<BasicBlock*, LVILatticeVal> BlockValues;
DEBUG(errs() << "Getting value " << *V << " on edge from '"
<< FromBB->getName() << "' to '" << ToBB->getName() << "'\n");
LVILatticeVal Result = GetValueOnEdge(V, FromBB, ToBB, BlockValues);
DEBUG(errs() << " Result = " << Result << "\n");
LVILatticeVal Result = getCache(PImpl).getValueOnEdge(V, FromBB, ToBB);
if (Result.isConstant())
return Result.getConstant();
@ -358,19 +444,7 @@ Constant *LazyValueInfo::getConstantOnEdge(Value *V, BasicBlock *FromBB,
LazyValueInfo::Tristate
LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
BasicBlock *FromBB, BasicBlock *ToBB) {
LVILatticeVal Result;
// If already a constant, we can use constant folding.
if (Constant *VC = dyn_cast<Constant>(V)) {
Result = LVILatticeVal::get(VC);
} else {
DenseMap<BasicBlock*, LVILatticeVal> BlockValues;
DEBUG(errs() << "Getting value " << *V << " on edge from '"
<< FromBB->getName() << "' to '" << ToBB->getName() << "'\n");
Result = GetValueOnEdge(V, FromBB, ToBB, BlockValues);
DEBUG(errs() << " Result = " << Result << "\n");
}
LVILatticeVal Result = getCache(PImpl).getValueOnEdge(V, FromBB, ToBB);
// If we know the value is a constant, evaluate the conditional.
Constant *Res = 0;
@ -378,7 +452,10 @@ LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
Res = ConstantFoldCompareInstOperands(Pred, Result.getConstant(), C, TD);
if (ConstantInt *ResCI = dyn_cast_or_null<ConstantInt>(Res))
return ResCI->isZero() ? False : True;
} else if (Result.isNotConstant()) {
return Unknown;
}
if (Result.isNotConstant()) {
// If this is an equality comparison, we can try to fold it knowing that
// "V != C1".
if (Pred == ICmpInst::ICMP_EQ) {
@ -394,6 +471,7 @@ LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
if (Res->isNullValue())
return True;
}
return Unknown;
}
return Unknown;