bool BranchProbabilityInfo::calcFloatingPointHeuristics(BasicBlock *BB) { BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator()); if (!BI || !BI->isConditional()) return false; Value *Cond = BI->getCondition(); FCmpInst *FCmp = dyn_cast<FCmpInst>(Cond); if (!FCmp) return false; bool isProb; if (FCmp->isEquality()) { // f1 == f2 -> Unlikely // f1 != f2 -> Likely isProb = !FCmp->isTrueWhenEqual(); } else if (FCmp->getPredicate() == FCmpInst::FCMP_ORD) { // !isnan -> Likely isProb = true; } else if (FCmp->getPredicate() == FCmpInst::FCMP_UNO) { // isnan -> Unlikely isProb = false; } else { return false; } unsigned TakenIdx = 0, NonTakenIdx = 1; if (!isProb) std::swap(TakenIdx, NonTakenIdx); setEdgeWeight(BB, TakenIdx, FPH_TAKEN_WEIGHT); setEdgeWeight(BB, NonTakenIdx, FPH_NONTAKEN_WEIGHT); return true; }