/// InsertPHITranslatedPointer - Insert a computation of the PHI translated /// version of 'V' for the edge PredBB->CurBB into the end of the PredBB /// block. All newly created instructions are added to the NewInsts list. /// This returns null on failure. /// Value *PHITransAddr:: InsertPHITranslatedSubExpr(Value *InVal, BasicBlock *CurBB, BasicBlock *PredBB, const DominatorTree &DT, SmallVectorImpl<Instruction*> &NewInsts) { // See if we have a version of this value already available and dominating // PredBB. If so, there is no need to insert a new instance of it. PHITransAddr Tmp(InVal, DL, AC); if (!Tmp.PHITranslateValue(CurBB, PredBB, &DT, /*MustDominate=*/true)) return Tmp.getAddr(); // We don't need to PHI translate values which aren't instructions. auto *Inst = dyn_cast<Instruction>(InVal); if (!Inst) return nullptr; // Handle cast of PHI translatable value. if (CastInst *Cast = dyn_cast<CastInst>(Inst)) { if (!isSafeToSpeculativelyExecute(Cast)) return nullptr; Value *OpVal = InsertPHITranslatedSubExpr(Cast->getOperand(0), CurBB, PredBB, DT, NewInsts); if (!OpVal) return nullptr; // Otherwise insert a cast at the end of PredBB. CastInst *New = CastInst::Create(Cast->getOpcode(), OpVal, InVal->getType(), InVal->getName() + ".phi.trans.insert", PredBB->getTerminator()); New->setDebugLoc(Inst->getDebugLoc()); NewInsts.push_back(New); return New; } // Handle getelementptr with at least one PHI operand. if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) { SmallVector<Value*, 8> GEPOps; BasicBlock *CurBB = GEP->getParent(); for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) { Value *OpVal = InsertPHITranslatedSubExpr(GEP->getOperand(i), CurBB, PredBB, DT, NewInsts); if (!OpVal) return nullptr; GEPOps.push_back(OpVal); } GetElementPtrInst *Result = GetElementPtrInst::Create( GEP->getSourceElementType(), GEPOps[0], makeArrayRef(GEPOps).slice(1), InVal->getName() + ".phi.trans.insert", PredBB->getTerminator()); Result->setDebugLoc(Inst->getDebugLoc()); Result->setIsInBounds(GEP->isInBounds()); NewInsts.push_back(Result); return Result; } #if 0 // FIXME: This code works, but it is unclear that we actually want to insert // a big chain of computation in order to make a value available in a block. // This needs to be evaluated carefully to consider its cost trade offs. // Handle add with a constant RHS. if (Inst->getOpcode() == Instruction::Add && isa<ConstantInt>(Inst->getOperand(1))) { // PHI translate the LHS. Value *OpVal = InsertPHITranslatedSubExpr(Inst->getOperand(0), CurBB, PredBB, DT, NewInsts); if (OpVal == 0) return 0; BinaryOperator *Res = BinaryOperator::CreateAdd(OpVal, Inst->getOperand(1), InVal->getName()+".phi.trans.insert", PredBB->getTerminator()); Res->setHasNoSignedWrap(cast<BinaryOperator>(Inst)->hasNoSignedWrap()); Res->setHasNoUnsignedWrap(cast<BinaryOperator>(Inst)->hasNoUnsignedWrap()); NewInsts.push_back(Res); return Res; } #endif return nullptr; }