#define DEBUG_TYPE "lazy-value-info"
#include "llvm/Analysis/LazyValueInfo.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
char LazyValueInfo::ID = 0;
static RegisterPass<LazyValueInfo>
X("lazy-value-info", "Lazy Value Information Analysis", false, true);
namespace llvm {
FunctionPass *createLazyValueInfoPass() { return new LazyValueInfo(); }
}
namespace {
class LVILatticeVal {
enum LatticeValueTy {
undefined,
constant,
notconstant,
overdefined
};
PointerIntPair<Constant *, 2, LatticeValueTy> Val;
public:
LVILatticeVal() : Val(0, undefined) {}
static LVILatticeVal get(Constant *C) {
LVILatticeVal Res;
Res.markConstant(C);
return Res;
}
static LVILatticeVal getNot(Constant *C) {
LVILatticeVal Res;
Res.markNotConstant(C);
return Res;
}
bool isUndefined() const { return Val.getInt() == undefined; }
bool isConstant() const { return Val.getInt() == constant; }
bool isNotConstant() const { return Val.getInt() == notconstant; }
bool isOverdefined() const { return Val.getInt() == overdefined; }
Constant *getConstant() const {
assert(isConstant() && "Cannot get the constant of a non-constant!");
return Val.getPointer();
}
Constant *getNotConstant() const {
assert(isNotConstant() && "Cannot get the constant of a non-notconstant!");
return Val.getPointer();
}
bool markOverdefined() {
if (isOverdefined())
return false;
Val.setInt(overdefined);
return true;
}
bool markConstant(Constant *V) {
if (isConstant()) {
assert(getConstant() == V && "Marking constant with different value");
return false;
}
assert(isUndefined());
Val.setInt(constant);
assert(V && "Marking constant with NULL");
Val.setPointer(V);
return true;
}
bool markNotConstant(Constant *V) {
if (isNotConstant()) {
assert(getNotConstant() == V && "Marking !constant with different value");
return false;
}
if (isConstant())
assert(getConstant() != V && "Marking not constant with different value");
else
assert(isUndefined());
Val.setInt(notconstant);
assert(V && "Marking constant with NULL");
Val.setPointer(V);
return true;
}
bool mergeIn(const LVILatticeVal &RHS) {
if (RHS.isUndefined() || isOverdefined()) return false;
if (RHS.isOverdefined()) return markOverdefined();
if (RHS.isNotConstant()) {
if (isNotConstant()) {
if (getNotConstant() != RHS.getNotConstant() ||
isa<ConstantExpr>(getNotConstant()) ||
isa<ConstantExpr>(RHS.getNotConstant()))
return markOverdefined();
return false;
}
if (isConstant()) {
if (getConstant() == RHS.getNotConstant() ||
isa<ConstantExpr>(RHS.getNotConstant()) ||
isa<ConstantExpr>(getConstant()))
return markOverdefined();
return markNotConstant(RHS.getNotConstant());
}
assert(isUndefined() && "Unexpected lattice");
return markNotConstant(RHS.getNotConstant());
}
if (isUndefined())
return markConstant(RHS.getConstant());
if (isConstant()) {
if (getConstant() != RHS.getConstant())
return markOverdefined();
return false;
}
if (getNotConstant() == RHS.getConstant() ||
isa<ConstantExpr>(getNotConstant()) ||
isa<ConstantExpr>(RHS.getConstant()))
return markOverdefined();
return false;
}
};
}
namespace llvm {
raw_ostream &operator<<(raw_ostream &OS, const LVILatticeVal &Val) {
if (Val.isUndefined())
return OS << "undefined";
if (Val.isOverdefined())
return OS << "overdefined";
if (Val.isNotConstant())
return OS << "notconstant<" << *Val.getNotConstant() << '>';
return OS << "constant<" << *Val.getConstant() << '>';
}
}
namespace {
class LazyValueInfoCache {
public:
typedef std::pair<BasicBlock*, LVILatticeVal> BlockCacheEntryTy;
typedef std::vector<BlockCacheEntryTy> ValueCacheEntryTy;
private:
DenseMap<Value*, ValueCacheEntryTy> ValueCache;
public:
LVILatticeVal getValueInBlock(Value *V, BasicBlock *BB);
LVILatticeVal getValueOnEdge(Value *V, BasicBlock *FromBB,BasicBlock *ToBB);
};
}
namespace {
struct BlockCacheEntryComparator {
static int Compare(const void *LHSv, const void *RHSv) {
const LazyValueInfoCache::BlockCacheEntryTy *LHS =
static_cast<const LazyValueInfoCache::BlockCacheEntryTy *>(LHSv);
const LazyValueInfoCache::BlockCacheEntryTy *RHS =
static_cast<const LazyValueInfoCache::BlockCacheEntryTy *>(RHSv);
if (LHS->first < RHS->first)
return -1;
if (LHS->first > RHS->first)
return 1;
return 0;
}
bool operator()(const LazyValueInfoCache::BlockCacheEntryTy &LHS,
const LazyValueInfoCache::BlockCacheEntryTy &RHS) const {
return LHS.first < RHS.first;
}
};
}
namespace {
class LVIQuery {
typedef LazyValueInfoCache::BlockCacheEntryTy BlockCacheEntryTy;
typedef LazyValueInfoCache::ValueCacheEntryTy ValueCacheEntryTy;
Value *Val;
ValueCacheEntryTy &Cache;
DenseMap<BasicBlock*, LVILatticeVal> NewBlockInfo;
public:
LVIQuery(Value *V, ValueCacheEntryTy &VC) : Val(V), Cache(VC) {
}
~LVIQuery() {
if (NewBlockInfo.empty()) return;
Cache.reserve(Cache.size() + NewBlockInfo.size());
if (NewBlockInfo.size() == 1) {
BlockCacheEntryTy Entry = *NewBlockInfo.begin();
ValueCacheEntryTy::iterator I =
std::lower_bound(Cache.begin(), Cache.end(), Entry,
BlockCacheEntryComparator());
assert((I == Cache.end() || I->first != Entry.first) &&
"Entry already in map!");
Cache.insert(I, Entry);
return;
}
Cache.insert(Cache.end(), NewBlockInfo.begin(), NewBlockInfo.end());
array_pod_sort(Cache.begin(), Cache.end(),
BlockCacheEntryComparator::Compare);
}
LVILatticeVal getBlockValue(BasicBlock *BB);
LVILatticeVal getEdgeValue(BasicBlock *FromBB, BasicBlock *ToBB);
private:
LVILatticeVal &getCachedEntryForBlock(BasicBlock *BB);
};
}
LVILatticeVal &LVIQuery::getCachedEntryForBlock(BasicBlock *BB) {
if (!Cache.empty()) {
ValueCacheEntryTy::iterator Entry =
std::lower_bound(Cache.begin(), Cache.end(),
BlockCacheEntryTy(BB, LVILatticeVal()),
BlockCacheEntryComparator());
if (Entry != Cache.end() && Entry->first == BB)
return Entry->second;
}
return NewBlockInfo[BB];
}
LVILatticeVal LVIQuery::getBlockValue(BasicBlock *BB) {
LVILatticeVal &BBLV = getCachedEntryForBlock(BB);
if (!BBLV.isUndefined()) {
DEBUG(dbgs() << " reuse BB '" << BB->getName() << "' val=" << BBLV <<'\n');
return BBLV;
}
BBLV.markOverdefined();
Instruction *BBI = dyn_cast<Instruction>(Val);
if (BBI == 0 || BBI->getParent() != BB) {
LVILatticeVal Result; unsigned NumPreds = 0;
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
Result.mergeIn(getEdgeValue(*PI, BB));
if (Result.isOverdefined()) {
DEBUG(dbgs() << " compute BB '" << BB->getName()
<< "' - overdefined because of pred.\n");
return Result;
}
++NumPreds;
}
if (NumPreds == 0 && BB == &BB->getParent()->front()) {
assert(isa<Argument>(Val) && "Unknown live-in to the entry block");
Result.markOverdefined();
return Result;
}
assert(!Result.isOverdefined());
return getCachedEntryForBlock(BB) = Result;
}
if (PHINode *PN = dyn_cast<PHINode>(BBI)) {
(void)PN;
} else {
}
DEBUG(dbgs() << " compute BB '" << BB->getName()
<< "' - overdefined because inst def found.\n");
LVILatticeVal Result;
Result.markOverdefined();
return getCachedEntryForBlock(BB) = Result;
}
LVILatticeVal LVIQuery::getEdgeValue(BasicBlock *BBFrom, BasicBlock *BBTo) {
if (BranchInst *BI = dyn_cast<BranchInst>(BBFrom->getTerminator())) {
if (BI->isConditional() &&
BI->getSuccessor(0) != BI->getSuccessor(1)) {
bool isTrueDest = BI->getSuccessor(0) == BBTo;
assert(BI->getSuccessor(!isTrueDest) == BBTo &&
"BBTo isn't a successor of BBFrom");
if (BI->getCondition() == Val)
return LVILatticeVal::get(ConstantInt::get(
Type::getInt1Ty(Val->getContext()), isTrueDest));
if (ICmpInst *ICI = dyn_cast<ICmpInst>(BI->getCondition()))
if (ICI->isEquality() && ICI->getOperand(0) == Val &&
isa<Constant>(ICI->getOperand(1))) {
if (isTrueDest == (ICI->getPredicate() == ICmpInst::ICMP_EQ))
return LVILatticeVal::get(cast<Constant>(ICI->getOperand(1)));
return LVILatticeVal::getNot(cast<Constant>(ICI->getOperand(1)));
}
}
}
if (SwitchInst *SI = dyn_cast<SwitchInst>(BBFrom->getTerminator())) {
if (SI->getCondition() == Val && SI->getDefaultDest() != BBTo) {
unsigned NumEdges = 0;
ConstantInt *EdgeVal = 0;
for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) {
if (SI->getSuccessor(i) != BBTo) continue;
if (NumEdges++) break;
EdgeVal = SI->getCaseValue(i);
}
assert(EdgeVal && "Missing successor?");
if (NumEdges == 1)
return LVILatticeVal::get(EdgeVal);
}
}
return getBlockValue(BBFrom);
}
LVILatticeVal LazyValueInfoCache::getValueInBlock(Value *V, BasicBlock *BB) {
if (Constant *VC = dyn_cast<Constant>(V))
return LVILatticeVal::get(VC);
DEBUG(dbgs() << "LVI Getting block end value " << *V << " at '"
<< BB->getName() << "'\n");
LVILatticeVal Result = LVIQuery(V, ValueCache[V]).getBlockValue(BB);
DEBUG(dbgs() << " Result = " << Result << "\n");
return Result;
}
LVILatticeVal LazyValueInfoCache::
getValueOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB) {
if (Constant *VC = dyn_cast<Constant>(V))
return LVILatticeVal::get(VC);
DEBUG(dbgs() << "LVI Getting edge value " << *V << " from '"
<< FromBB->getName() << "' to '" << ToBB->getName() << "'\n");
LVILatticeVal Result =
LVIQuery(V, ValueCache[V]).getEdgeValue(FromBB, ToBB);
DEBUG(dbgs() << " Result = " << Result << "\n");
return Result;
}
bool LazyValueInfo::runOnFunction(Function &F) {
TD = getAnalysisIfAvailable<TargetData>();
return false;
}
static LazyValueInfoCache &getCache(void *&PImpl) {
if (!PImpl)
PImpl = new LazyValueInfoCache();
return *static_cast<LazyValueInfoCache*>(PImpl);
}
void LazyValueInfo::releaseMemory() {
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;
}
Constant *LazyValueInfo::getConstantOnEdge(Value *V, BasicBlock *FromBB,
BasicBlock *ToBB) {
LVILatticeVal Result = getCache(PImpl).getValueOnEdge(V, FromBB, ToBB);
if (Result.isConstant())
return Result.getConstant();
return 0;
}
LazyValueInfo::Tristate
LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
BasicBlock *FromBB, BasicBlock *ToBB) {
LVILatticeVal Result = getCache(PImpl).getValueOnEdge(V, FromBB, ToBB);
Constant *Res = 0;
if (Result.isConstant()) {
Res = ConstantFoldCompareInstOperands(Pred, Result.getConstant(), C, TD);
if (ConstantInt *ResCI = dyn_cast_or_null<ConstantInt>(Res))
return ResCI->isZero() ? False : True;
return Unknown;
}
if (Result.isNotConstant()) {
if (Pred == ICmpInst::ICMP_EQ) {
Res = ConstantFoldCompareInstOperands(ICmpInst::ICMP_NE,
Result.getNotConstant(), C, TD);
if (Res->isNullValue())
return False;
} else if (Pred == ICmpInst::ICMP_NE) {
Res = ConstantFoldCompareInstOperands(ICmpInst::ICMP_NE,
Result.getNotConstant(), C, TD);
if (Res->isNullValue())
return True;
}
return Unknown;
}
return Unknown;
}