C++ IR::is_exp方法代码示例

//'usevec': for local used.
bool IR_CP::doProp(IN IRBB * bb, Vector<IR*> & usevec)
{
    bool change = false;
    C<IR*> * cur_iter, * next_iter;

    for (BB_irlist(bb).get_head(&cur_iter),
         next_iter = cur_iter; cur_iter != NULL; cur_iter = next_iter) {

        IR * def_stmt = cur_iter->val();

        BB_irlist(bb).get_next(&next_iter);

        if (!is_copy(def_stmt)) { continue; }

        DUSet const* useset = NULL;
        UINT num_of_use = 0;
        SSAInfo * ssainfo = NULL;
        bool ssadu = false;
        if ((ssainfo = def_stmt->get_ssainfo()) != NULL &&
            SSA_uses(ssainfo).get_elem_count() != 0) {
            //Record use_stmt in another vector to facilitate this function
            //if it is not in use-list any more after copy-propagation.
            SEGIter * sc;
            for    (INT u = SSA_uses(ssainfo).get_first(&sc);
                 u >= 0; u = SSA_uses(ssainfo).get_next(u, &sc)) {
                IR * use = m_ru->get_ir(u);
                ASSERT0(use);
                usevec.set(num_of_use, use);
                num_of_use++;
            }
            ssadu = true;
        } else if (def_stmt->get_exact_ref() == NULL &&
                   !def_stmt->is_void()) {
            //Allowing copy propagate exact or VOID value.
            continue;
        } else if ((useset = def_stmt->readDUSet()) != NULL &&
                   useset->get_elem_count() != 0) {
            //Record use_stmt in another vector to facilitate this function
            //if it is not in use-list any more after copy-propagation.
            DUIter di = NULL;
            for (INT u = useset->get_first(&di);
                 u >= 0; u = useset->get_next(u, &di)) {
                IR * use = m_ru->get_ir(u);
                usevec.set(num_of_use, use);
                num_of_use++;
            }
        } else  {
            continue;
        }

        IR const* prop_value = get_propagated_value(def_stmt);

        for (UINT i = 0; i < num_of_use; i++) {
            IR * use = usevec.get(i);
            ASSERT0(use->is_exp());
            IR * use_stmt = use->get_stmt();
            ASSERT0(use_stmt->is_stmt());

            ASSERT0(use_stmt->get_bb() != NULL);
            IRBB * use_bb = use_stmt->get_bb();
            if (!ssadu &&
                !(bb == use_bb && bb->is_dom(def_stmt, use_stmt, true)) &&
                !m_cfg->is_dom(BB_id(bb), BB_id(use_bb))) {
                //'def_stmt' must dominate 'use_stmt'.
                //e.g:
                //    if (...) {
                //        g = 10; //S1
                //    }
                //    ... = g; //S2
                //g can not be propagted since S1 is not dominate S2.
                continue;
            }

            if (!is_available(def_stmt, prop_value, use_stmt)) {
                //The value that will be propagated can
                //not be killed during 'ir' and 'use_stmt'.
                //e.g:
                //    g = a; //S1
                //    if (...) {
                //        a = ...; //S3
                //    }
                //    ... = g; //S2
                //g can not be propagted since a is killed by S3.
                continue;
            }

            if (!ssadu && !m_du->isExactAndUniqueDef(def_stmt, use)) {
                //Only single definition is allowed.
                //e.g:
                //    g = 20; //S3
                //    if (...) {
                //        g = 10; //S1
                //    }
                //    ... = g; //S2
                //g can not be propagted since there are
                //more than one definitions are able to get to S2.
                continue;
            }

//.........这里部分代码省略.........