LoopPassBase.hpp

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/* src/vm/jit/compiler2/LoopPassBase.hpp - LoopPassBase

   Copyright (C) 2013
   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO

   This file is part of CACAO.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.

*/

#ifndef _JIT_COMPILER2_LOOPPASSBASE
#define _JIT_COMPILER2_LOOPPASSBASE

#include "vm/jit/compiler2/Pass.hpp"
#include "vm/jit/compiler2/JITData.hpp"
#include "vm/jit/compiler2/LoopBase.hpp"
#include "vm/jit/compiler2/GraphHelper.hpp"

#include "toolbox/UnionFind.hpp"

#include "vm/jit/compiler2/alloc/set.hpp"
#include "vm/jit/compiler2/alloc/map.hpp"
#include "vm/jit/compiler2/alloc/vector.hpp"

namespace cacao {
namespace jit {
namespace compiler2 {

/**
 * Calculate the Loop Tree.
 *
 * The algorithm used here is based on the method proposed in
 * "Testing Flow Graph Reducibility" by Tarjan @cite Tarjan1974
 * with the modifications in "SSA-Based Reduction of Operator Strengh" by
 * Vick @cite VickMScThesis. See also Click's Phd Thesis, Chapter 6
 * @cite ClickPHD.
 */
template <class _T>
class LoopPassBase : public Pass, public memory::ManagerMixin<LoopPassBase<_T> >, public LoopTreeBase<_T> {
private:
    typedef _T NodeType;
    typedef typename alloc::set<const NodeType *>::type NodeListTy;
    typedef typename alloc::map<const NodeType *,NodeListTy>::type NodeListMapTy;
    typedef typename alloc::vector<const NodeType *>::type NodeMapTy;
    typedef typename alloc::map<const NodeType *,int>::type IndexMapTy;
    typedef typename alloc::map<const NodeType *,const NodeType *>::type EdgeMapTy;

    #if 0
    EdgeMapTy parent;
    NodeListMapTy pred;
    #endif
    NodeListMapTy bucket;
    IndexMapTy semi;
    NodeMapTy vertex;
    int n;

    EdgeMapTy ancestor;
    EdgeMapTy label;

    NodeListTy& succ(const NodeType *v, NodeListTy &list);
    #if 0
    void DFS(const NodeType * v);

    void Link(const NodeType *v, const NodeType *w);
    const NodeType* Eval(const NodeType *v);
    void Compress(const NodeType *v);
    #endif

    NodeType* get_init_node(JITData &JD);
public:
    static char ID;
    LoopPassBase() : Pass() {}
    virtual bool run(JITData &JD);
    virtual PassUsage& get_PassUsage(PassUsage &PU) const;
};

template<class NodeType>
class LoopComparator {
private:
    DFSTraversal<NodeType> &dfs;
public:
    LoopComparator(DFSTraversal<NodeType> &dfs) : dfs(dfs) {}
    bool operator() (const LoopBase<NodeType> *a, const LoopBase<NodeType>* b) {
        NodeType *a_i = a->get_header();
        NodeType *b_i = b->get_header();
        if (dfs[a_i] == dfs[b_i]) {
            a_i = a->get_exit();
            b_i = b->get_exit();
        }
        return dfs[a_i] < dfs[b_i];
    }
};

template <class _T>
inline bool LoopPassBase<_T>::run(JITData &JD) {
    DFSTraversal<NodeType> dfs(get_init_node(JD));
    int size = dfs.size();

    alloc::vector<alloc::set<int>::type >::type backedges(size);
    alloc::vector<alloc::set<int>::type >::type forwardedges(size);
    alloc::vector<alloc::set<int>::type >::type crossedges(size);
    alloc::vector<alloc::set<int>::type >::type treeedges(size);
    alloc::vector<int>::type highpt(size,-1);

    int end = -1;

    UnionFindImpl<int> unionfind(end);

    // store the loop for each bb
    typename alloc::vector<LoopBase<NodeType>*>::type index_to_loop(size);


    // initialization
    for (typename DFSTraversal<NodeType>::iterator i = dfs.begin(), e = dfs.end();
            i != e ; ++i) {
        int v = i.get_index();

        unionfind.make_set(v);
        // get successors
        typename DFSTraversal<NodeType>::iterator_list successors;
        i.get_successors(successors);

        for (typename DFSTraversal<NodeType>::iterator_list::iterator ii = successors.begin(),
                ee = successors.end(); ii != ee ; ++ii) {
            int w = (*ii).get_index();
            // edge v -> w

            if ((*ii).get_parent() != i) {
                if (dfs.is_ancestor(v,w)) {
                    // forward edge
                    forwardedges[w].insert(v);
                } else if (dfs.is_decendant(v,w)) {
                    // backward edge
                    backedges[w].insert(v);
                } else {
                    // cross edge
                    crossedges[w].insert(v);
                }
            } else {
                // tree edge
                treeedges[w].insert(v);
            }
        }
    }


    #if 0
    for (int w = 0; w < size ; ++w ) {
        alloc::set<int>::type set = treeedges[w];
        // print treeedge
        for(alloc::set<int>::type::iterator i = set.begin(), e = set.end(); i != e ; ++i) {
            int v = *i;
            //LOG2("treeedge:    " << setw(3) << v << " -> " << setw(3) << w << nl);
        }
        // print backedge
        set = backedges[w];
        for(alloc::set<int>::type::iterator i = set.begin(), e = set.end(); i != e ; ++i) {
            int v = *i;
            //LOG2("backedge:    " << setw(3) << v << " -> " << setw(3) << w << nl);
        }
        // print forwardedge
        set = forwardedges[w];
        for(alloc::set<int>::type::iterator i = set.begin(), e = set.end(); i != e ; ++i) {
            int v = *i;
            //LOG2("forwardedge: " << setw(3) << v << " -> " << setw(3) << w << nl);
        }
        // print crossedge
        set = crossedges[w];
        for(alloc::set<int>::type::iterator i = set.begin(), e = set.end(); i != e ; ++i) {
            int v = *i;
            //LOG2("crossedge:   " << setw(3) << v << " -> " << setw(3) << w << nl);
        }
    }
    #endif

    alloc::set<int>::type P;
    alloc::set<int>::type Q;
    for (typename DFSTraversal<NodeType>::reverse_iterator i = dfs.rbegin(), e = dfs.rend();
            i != e ; --i) {
        int w = i.get_index();
        //LOG2("w=" << w << nl);

        P.clear();
        Q.clear();

        // get incoming backedges
        alloc::set<int>::type &backedges_w = backedges[w];
        for(alloc::set<int>::type::iterator i = backedges_w.begin(), e = backedges_w.end();
                i != e; ++i) {
            int v = *i;
            int v_r = unionfind.find(v);
            assert(v_r != end && "Element not found!");
            P.insert(v_r);
            Q.insert(v_r);

            // create a new loop
            LoopBase<NodeType> *loop = this->add_loop(dfs[w],dfs[v]);

            // set loop
            if(!index_to_loop[v]) {
                index_to_loop[v] = loop;
            }
            if (index_to_loop[w]) {
                LoopBase<NodeType> *inner_loop = index_to_loop[w];
                if(inner_loop != loop) {
                    loop->add_inner_loop(inner_loop);
                }
            }

            //LOG2("Q=P= ");
            //DEBUG2(print_container(dbg(), Q.begin(),Q.end()));
            //LOG2(nl);

            // Q contains the sources of the backedges to w.
            // It must be order from smallest to largest preorder source to
            // guarantee strict inner to outer ordering.
            while (!Q.empty()) {
                int x;
                // simulate pop_front
                { // new scope
                    alloc::set<int>::type::iterator x_it = Q.begin();
                    x = *x_it;
                    Q.erase(x_it);
                }
                //LOG2("x=" << x << nl);

                // is loop header?
                if (backedges[x].size() != 0) {
                    LoopBase<NodeType> *inner_loop = index_to_loop[x];
                    assert(inner_loop);
                    if(inner_loop != loop) {
                        loop->add_inner_loop(inner_loop);
                    }
                }

                alloc::set<int>::type incoming;
                // collect incoming edges
                { // new scope
                    alloc::set<int>::type ref1 = forwardedges[x];
                    incoming.insert(ref1.begin(), ref1.end());
                    alloc::set<int>::type ref2 = treeedges[x];
                    incoming.insert(ref2.begin(), ref2.end());
                    alloc::set<int>::type ref3 = crossedges[x];
                    incoming.insert(ref3.begin(), ref3.end());
                }
                for(alloc::set<int>::type::iterator i = incoming.begin(), e = incoming.end();
                        i != e; ++i) {
                    int y = *i;
                    //LOG2("y=" << y << nl);
                    int y_r = unionfind.find(y);
                    assert(y_r != end);
                    //LOG2("y_r=" << y_r << nl);

                    //LOG("ND(w)=" << dfs.num_decendants(w) << nl);
                    // test for reducibility
                    // TODO <= vs <
                    // if ( (w > y_r) || ( (w + dfs.num_decendants(w)) <= y_r) ) {
                    if ( (w > y_r) || ( (w + dfs.num_decendants(w)) < y_r) ) {
                        assert(0 && "Graph is irreduciable. Can not yet deal with it.");
                    }

                    // add y_r if appropriate
                    if ( P.find(y_r) == P.end() and y_r != w) {
                        P.insert(y_r);
                        Q.insert(y_r);
                    }

                    // set highpt
                    if (highpt[y_r] == -1) {
                        highpt[y_r] = w;
                    }

                    // set loop
                    if (!index_to_loop[y_r]) {
                        index_to_loop[y_r] = loop;
                    }
                }
            }
        }

        // now P = P(w) in the current graph
        for(alloc::set<int>::type::iterator i = P.begin(), e = P.end();
                i != e; ++i) {
            int x = *i;
            unionfind.set_union(x,w);
        }
        // duplicate edges?

    }
    for (int w = 0; w < size ; ++w ) {
        //LOG2("highpt[" << w << "]=" << highpt[w] << nl);
    }
    for (int w = 0; w < size ; ++w ) {
        LoopBase<NodeType> *loop = index_to_loop[w];
        if (!loop) {
            //LOG2("loop(" << dfs[w] << ") not in a loop" << nl);
            continue;
        }
        this->set_loop(dfs[w],loop);
        //LOG2("loop(header = " << dfs[w] << ") = " << loop << nl);
    }

    // sort from outermost to innermost loop
    LoopComparator<NodeType> compare_loop(dfs);
    std::sort(LoopTreeBase<NodeType>::begin(), LoopTreeBase<NodeType>::end(), compare_loop);

    // add NodeType to loops
    for (typename LoopTreeBase<NodeType>::LoopListTy::reverse_iterator
            i = LoopTreeBase<NodeType>::loops.rbegin(), e = LoopTreeBase<NodeType>::loops.rend();
                i != e; ++i) {
        LoopBase<NodeType> *loop = *i;
        //LOG("Loop: " << loop << nl);
        LoopBase<NodeType> *parent = loop->get_parent();
        if (parent) {
            //LOG("parent: " << parent << nl);
        } else {
            LoopTreeBase<NodeType>::add_top_loop(loop);
            //LOG("parent: " << "toplevel" << nl);
        }
        // add to loop headers
        LoopTreeBase<NodeType>::insert_loop_header(loop->get_header(),loop);
    }
    return true;
}

} // end namespace compiler2
} // end namespace jit
} // end namespace cacao

#endif /* _JIT_COMPILER2_LOOPPASSBASE */


/*
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 * Please do not remove this and leave it at the end of the file, where
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