예제 #1
0
Opnd* OpndUtils::findImmediateSource(Opnd* opnd) 
{
    Opnd* res = opnd;
    while (!res->isPlacedIn(OpndKind_Imm)) {
        Inst* defInst = res->getDefiningInst();
        if (!defInst || defInst->getMnemonic()!=Mnemonic_MOV) {
            return NULL;
        }
        res = defInst->getOpnd(1);
    }
    return res;
}
예제 #2
0
//_________________________________________________________________________________________________
void DCE::runImpl()
{
    bool early = false;
    getArg("early", early);
    if (early && !irManager->getCGFlags()->earlyDCEOn) {
        return;
    }

    irManager->updateLivenessInfo();
    irManager->calculateOpndStatistics();
    BitSet ls(irManager->getMemoryManager(), irManager->getOpndCount());
    const Nodes& nodes = irManager->getFlowGraph()->getNodesPostOrder();

#ifdef ORDER

    MemoryManager mm("dce_parents");

    U_32 opndCount = irManager->getOpndCount();
    bool * isParentOpnd = new(mm) bool [opndCount];
    memset(isParentOpnd, 0, sizeof(bool) * opndCount);
    for (Nodes::const_iterator it = nodes.begin(),end = nodes.end(); it!=end; ++it) {
        Node* node = *it;
        for (Inst * inst=(Inst*)node->getLastInst(); inst!=NULL; inst=inst->getPrevInst()) {
            Opnd* load_obj = inst->getParentObjectLoad();
            if (load_obj)
            {
                isParentOpnd[load_obj->getId()] = true;
            }

            Opnd* store_obj = inst->getParentObjectStore();
            if (store_obj)
            {
                isParentOpnd[store_obj->getId()] = true;
            }

        }
    }
#endif



    for (Nodes::const_iterator it = nodes.begin(),end = nodes.end(); it!=end; ++it) {
        Node* node = *it;
        if (node->isBlockNode()) {
            //Here we'll try to remove redundant branches that could appear after
            //branch translations. All such branches are supposed to be conditional.
            Inst * inst = (Inst *)node->getLastInst();
            if(inst && node->getOutEdges().size() > 1) {
                Edges edges = node->getOutEdges();
                for (Edges::const_iterator ite1 = ++edges.begin(), end = edges.end(); ite1 != end; ++ite1) {
                    for (Edges::const_iterator ite2 = edges.begin(); ite1 != ite2; ++ite2) {
                        Edge *edge1 = *ite1;
                        Edge *edge2 = *ite2;
                        assert(edge1 != edge2);

                        //If this condition is satisfied then there are at least two branches with
                        //the same destination
                        if (edge1->getTargetNode() == edge2->getTargetNode()) {
                            //Check that edges are conditional and the last instruction is branch,
                            //the other situations are not permitted at the moment
                            assert(inst->hasKind(Inst::Kind_BranchInst));
                            assert(edge1->getKind() == Edge::Kind_True ||
                                   edge1->getKind() == Edge::Kind_False);
                            assert(edge2->getKind() == Edge::Kind_True ||
                                   edge2->getKind() == Edge::Kind_False);

                            //Remove last instruction if it is a branch
                            inst->unlink();
                            irManager->getFlowGraph()->removeEdge(edge2);
                        }

                    }
                }
            }

            irManager->getLiveAtExit(node, ls);
            for (Inst * inst=(Inst*)node->getLastInst(), * prevInst=NULL; inst!=NULL; inst=prevInst) {
                prevInst=inst->getPrevInst();
                // Prevent debug traps or instructions with side effects
                // like (MOVS) from being removed.
                bool deadInst=!inst->hasSideEffect() && (inst->getMnemonic() != Mnemonic_INT3);

#ifdef ORDER //yzm
                for (unsigned int i = 0 ; i < inst->getOpndCount() ; i ++)
                {
                    Opnd* opnd = inst->getOpnd(i);
                    if (isParentOpnd[opnd->getId()])
                        deadInst = false;
                }
#endif

                if (deadInst) {
                    if (inst->hasKind(Inst::Kind_CopyPseudoInst)) {
                        Opnd * opnd=inst->getOpnd(1);
                        if (opnd->getType()->isFP() && opnd->getDefiningInst()!=NULL && opnd->getDefiningInst()->getMnemonic()==Mnemonic_CALL) {
                            deadInst=false;
                        }
                    }
                    if (deadInst) {
                        Inst::Opnds opnds(inst, Inst::OpndRole_All);
                        for (Inst::Opnds::iterator ito = opnds.begin(); ito != opnds.end(); ito = opnds.next(ito)) {
                            Opnd * opnd = inst->getOpnd(ito);
                            if ((ls.getBit(opnd->getId()) && (inst->getOpndRoles(ito) & Inst::OpndRole_Def)) ||
                                    (((opnd->getMemOpndKind()&(MemOpndKind_Heap|MemOpndKind_StackManualLayout))!=0) && (inst->getMnemonic() != Mnemonic_LEA))) {
                                deadInst=false;
                                break;
                            }
                        }
                    }
                }
                if (deadInst) {
                    inst->unlink();
                } else {
                    irManager->updateLiveness(inst, ls);
                }
            }
            irManager->getLiveAtEntry(node)->copyFrom(ls);
        }
    }

    irManager->eliminateSameOpndMoves();

    irManager->getFlowGraph()->purgeEmptyNodes();
    irManager->getFlowGraph()->mergeAdjacentNodes(true, false);
    irManager->getFlowGraph()->purgeUnreachableNodes();

    irManager->packOpnds();
    irManager->invalidateLivenessInfo();
}