+
+
+Value *InductionVariable::getExecutionCount(LoopInfo *LoopInfo) {
+ if (InductionType != Canonical) return 0;
+
+ DEBUG(std::cerr << "entering getExecutionCount\n");
+
+ // Don't recompute if already available
+ if (End) {
+ DEBUG(std::cerr << "returning cached End value.\n");
+ return End;
+ }
+
+ const Loop *L = LoopInfo ? LoopInfo->getLoopFor(Phi->getParent()) : 0;
+ if (!L) {
+ DEBUG(std::cerr << "null loop. oops\n");
+ return 0;
+ }
+
+ // >1 backedge => cannot predict number of iterations
+ if (Phi->getNumIncomingValues() != 2) {
+ DEBUG(std::cerr << ">2 incoming values. oops\n");
+ return 0;
+ }
+
+ // Find final node: predecessor of the loop header that's also an exit
+ BasicBlock *terminator = 0;
+ for (pred_iterator PI = pred_begin(L->getHeader()),
+ PE = pred_end(L->getHeader()); PI != PE; ++PI)
+ if (L->isLoopExit(*PI)) {
+ terminator = *PI;
+ break;
+ }
+
+ // Break in the loop => cannot predict number of iterations
+ // break: any block which is an exit node whose successor is not in loop,
+ // and this block is not marked as the terminator
+ //
+ const std::vector<BasicBlock*> &blocks = L->getBlocks();
+ for (std::vector<BasicBlock*>::const_iterator I = blocks.begin(),
+ e = blocks.end(); I != e; ++I)
+ if (L->isLoopExit(*I) && *I != terminator)
+ for (succ_iterator SI = succ_begin(*I), SE = succ_end(*I); SI != SE; ++SI)
+ if (!L->contains(*SI)) {
+ DEBUG(std::cerr << "break found in loop");
+ return 0;
+ }
+
+ BranchInst *B = dyn_cast<BranchInst>(terminator->getTerminator());
+ if (!B) {
+ DEBUG(std::cerr << "Terminator is not a cond branch!");
+ return 0;
+ }
+ SetCondInst *SCI = dyn_cast<SetCondInst>(B->getCondition());
+ if (!SCI) {
+ DEBUG(std::cerr << "Not a cond branch on setcc!\n");
+ return 0;
+ }
+
+ DEBUG(std::cerr << "sci:" << *SCI);
+ Value *condVal0 = SCI->getOperand(0);
+ Value *condVal1 = SCI->getOperand(1);
+
+ // The induction variable is the one coming from the backedge
+ Value *indVar = Phi->getIncomingValue(L->contains(Phi->getIncomingBlock(1)));
+
+
+ // Check to see if indVar is one of the parameters in SCI and if the other is
+ // loop-invariant, it is the UB
+ if (indVar == condVal0) {
+ if (isLoopInvariant(condVal1, L))
+ End = condVal1;
+ else {
+ DEBUG(std::cerr << "not loop invariant 1\n");
+ return 0;
+ }
+ } else if (indVar == condVal1) {
+ if (isLoopInvariant(condVal0, L))
+ End = condVal0;
+ else {
+ DEBUG(std::cerr << "not loop invariant 0\n");
+ return 0;
+ }
+ } else {
+ DEBUG(std::cerr << "Loop condition doesn't directly uses indvar\n");
+ return 0;
+ }
+
+ switch (SCI->getOpcode()) {
+ case Instruction::SetLT:
+ case Instruction::SetNE: return End; // already done
+ case Instruction::SetLE:
+ // if compared to a constant int N, then predict N+1 iterations
+ if (ConstantSInt *ubSigned = dyn_cast<ConstantSInt>(End)) {
+ DEBUG(std::cerr << "signed int constant\n");
+ return ConstantSInt::get(ubSigned->getType(), ubSigned->getValue()+1);
+ } else if (ConstantUInt *ubUnsigned = dyn_cast<ConstantUInt>(End)) {
+ DEBUG(std::cerr << "unsigned int constant\n");
+ return ConstantUInt::get(ubUnsigned->getType(),
+ ubUnsigned->getValue()+1);
+ } else {
+ DEBUG(std::cerr << "symbolic bound\n");
+ // new expression N+1, insert right before the SCI. FIXME: If End is loop
+ // invariant, then so is this expression. We should insert it in the loop
+ // preheader if it exists.
+ return BinaryOperator::create(Instruction::Add, End,
+ ConstantInt::get(End->getType(), 1),
+ "tripcount", SCI);
+ }
+
+ default:
+ return 0; // cannot predict
+ }
+}
+
+
+void InductionVariable::print(std::ostream &o) const {
+ switch (InductionType) {
+ case InductionVariable::Canonical: o << "Canonical "; break;
+ case InductionVariable::SimpleLinear: o << "SimpleLinear "; break;
+ case InductionVariable::Linear: o << "Linear "; break;
+ case InductionVariable::Unknown: o << "Unrecognized "; break;
+ }
+ o << "Induction Variable: ";
+ if (Phi) {
+ WriteAsOperand(o, Phi);
+ o << ":\n" << Phi;
+ } else {
+ o << "\n";
+ }
+ if (InductionType == InductionVariable::Unknown) return;
+
+ o << " Start = "; WriteAsOperand(o, Start);
+ o << " Step = " ; WriteAsOperand(o, Step);
+ if (End) {
+ o << " End = " ; WriteAsOperand(o, End);
+ }
+ o << "\n";
+}