#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;
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()) {
+ return markOverdefined();
}
assert(isUndefined() && "Unexpected lattice");
return markOverdefined();
else
return markConstantRange(NewR);
+ } else if (!isUndefined()) {
+ return markOverdefined();
}
assert(isUndefined() && "Unexpected lattice");
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,
/// 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,
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 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;
- Result.markOverdefined();
- return 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;
+ }
+
+ return Cache[BB] = Result;
}
// Figure out the possible values of the query BEFORE this branch.
LVILatticeVal InBlock = getBlockValue(BBFrom);
- if (!InBlock.isConstantRange()) return InBlock;
+ if (!InBlock.isConstantRange())
+ return LVILatticeVal::getRange(TrueValues);
// Find all potential values that satisfy both the input and output
// conditions.
// 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;
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()))
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