class raw_ostream;
template<typename T> class SmallVectorImpl;
-
+
/// AbstractLatticeFunction - This class is implemented by the dataflow instance
/// to specify what the lattice values are and how they handle merges etc.
/// This gives the client the power to compute lattice values from instructions,
UntrackedVal = untrackedVal;
}
virtual ~AbstractLatticeFunction();
-
+
LatticeVal getUndefVal() const { return UndefVal; }
LatticeVal getOverdefinedVal() const { return OverdefinedVal; }
LatticeVal getUntrackedVal() const { return UntrackedVal; }
-
+
/// IsUntrackedValue - If the specified Value is something that is obviously
/// uninteresting to the analysis (and would always return UntrackedVal),
/// this function can return true to avoid pointless work.
virtual bool IsUntrackedValue(Value *V) {
return false;
}
-
+
/// ComputeConstant - Given a constant value, compute and return a lattice
/// value corresponding to the specified constant.
virtual LatticeVal ComputeConstant(Constant *C) {
virtual bool IsSpecialCasedPHI(PHINode *PN) {
return false;
}
-
+
/// GetConstant - If the specified lattice value is representable as an LLVM
/// constant value, return it. Otherwise return null. The returned value
/// must be in the same LLVM type as Val.
virtual LatticeVal ComputeArgument(Argument *I) {
return getOverdefinedVal(); // always safe
}
-
+
/// MergeValues - Compute and return the merge of the two specified lattice
/// values. Merging should only move one direction down the lattice to
/// guarantee convergence (toward overdefined).
virtual LatticeVal MergeValues(LatticeVal X, LatticeVal Y) {
return getOverdefinedVal(); // always safe, never useful.
}
-
+
/// ComputeInstructionState - Given an instruction and a vector of its operand
/// values, compute the result value of the instruction.
virtual LatticeVal ComputeInstructionState(Instruction &I, SparseSolver &SS) {
return getOverdefinedVal(); // always safe, never useful.
}
-
+
/// PrintValue - Render the specified lattice value to the specified stream.
virtual void PrintValue(LatticeVal V, raw_ostream &OS);
};
-
+
/// SparseSolver - This class is a general purpose solver for Sparse Conditional
/// Propagation with a programmable lattice function.
///
class SparseSolver {
typedef AbstractLatticeFunction::LatticeVal LatticeVal;
-
+
/// LatticeFunc - This is the object that knows the lattice and how to do
/// compute transfer functions.
AbstractLatticeFunction *LatticeFunc;
-
+
DenseMap<Value*, LatticeVal> ValueState; // The state each value is in.
SmallPtrSet<BasicBlock*, 16> BBExecutable; // The bbs that are executable.
-
+
std::vector<Instruction*> InstWorkList; // Worklist of insts to process.
-
+
std::vector<BasicBlock*> BBWorkList; // The BasicBlock work list
-
+
/// KnownFeasibleEdges - Entries in this set are edges which have already had
/// PHI nodes retriggered.
typedef std::pair<BasicBlock*,BasicBlock*> Edge;
~SparseSolver() {
delete LatticeFunc;
}
-
+
/// Solve - Solve for constants and executable blocks.
///
void Solve(Function &F);
-
+
void Print(Function &F, raw_ostream &OS) const;
/// getLatticeState - Return the LatticeVal object that corresponds to the
DenseMap<Value*, LatticeVal>::const_iterator I = ValueState.find(V);
return I != ValueState.end() ? I->second : LatticeFunc->getUntrackedVal();
}
-
+
/// getOrInitValueState - Return the LatticeVal object that corresponds to the
/// value, initializing the value's state if it hasn't been entered into the
/// map yet. This function is necessary because not all values should start
/// constants should be marked as constants.
///
LatticeVal getOrInitValueState(Value *V);
-
+
/// isEdgeFeasible - Return true if the control flow edge from the 'From'
/// basic block to the 'To' basic block is currently feasible. If
/// AggressiveUndef is true, then this treats values with unknown lattice
bool isBlockExecutable(BasicBlock *BB) const {
return BBExecutable.count(BB);
}
-
+
private:
/// UpdateState - When the state for some instruction is potentially updated,
/// this function notices and adds I to the worklist if needed.
void UpdateState(Instruction &Inst, LatticeVal V);
-
+
/// MarkBlockExecutable - This method can be used by clients to mark all of
/// the blocks that are known to be intrinsically live in the processed unit.
void MarkBlockExecutable(BasicBlock *BB);
-
+
/// markEdgeExecutable - Mark a basic block as executable, adding it to the BB
/// work list if it is not already executable.
void markEdgeExecutable(BasicBlock *Source, BasicBlock *Dest);
-
+
/// getFeasibleSuccessors - Return a vector of booleans to indicate which
/// successors are reachable from a given terminator instruction.
void getFeasibleSuccessors(TerminatorInst &TI, SmallVectorImpl<bool> &Succs,
bool AggressiveUndef);
-
+
void visitInst(Instruction &I);
void visitPHINode(PHINode &I);
void visitTerminatorInst(TerminatorInst &TI);