jdk/src/hotspot/share/opto/multnode.hpp

/*
 * Copyright (c) 1997, 2026, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_OPTO_MULTNODE_HPP
#define SHARE_OPTO_MULTNODE_HPP

#include "opto/node.hpp"

class Matcher;
class ProjNode;

//------------------------------MultiNode--------------------------------------
// This class defines a MultiNode, a Node which produces many values.  The
// values are wrapped up in a tuple Type, i.e. a TypeTuple.
class MultiNode : public Node {
public:
  MultiNode( uint required ) : Node(required) {
    init_class_id(Class_Multi);
  }
  virtual int Opcode() const;
  virtual const Type *bottom_type() const = 0;
  virtual bool       is_CFG() const { return true; }
  virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash
  virtual const RegMask &out_RegMask() const;
  virtual Node *match( const ProjNode *proj, const Matcher *m );
  virtual uint ideal_reg() const { return NotAMachineReg; }
  ProjNode* proj_out(uint which_proj) const; // Get a named projection
  ProjNode* proj_out_or_null(uint which_proj) const;
  ProjNode* proj_out_or_null(uint which_proj, bool is_io_use) const;
  uint number_of_projs(uint which_proj) const;
  uint number_of_projs(uint which_proj, bool is_io_use) const;

protected:

  // Provide single interface for DUIterator_Fast/DUIterator for template method below
  class UsesIteratorFast {
    DUIterator_Fast& _imax;
    DUIterator_Fast& _i;
    const Node* _node;

  public:
    bool cont() {
      return _i < _imax;
    }
    void next() {
      _i++;
    }
    Node* current() {
      return _node->fast_out(_i);
    }
    UsesIteratorFast(DUIterator_Fast& imax, DUIterator_Fast& i, const Node* node)
      : _imax(imax), _i(i), _node(node) {
    }
  };

  class UsesIterator {
    DUIterator& _i;
    const Node* _node;

  public:
    bool cont() {
      return _node->has_out(_i);
    }
    void next() {
      _i++;
    }
    Node* current() {
      return _node->out(_i);
    }
    UsesIterator(DUIterator& i, const Node* node)
      : _i(i), _node(node) {
    }
  };

  // Iterate with i over all Proj uses calling callback
  template<class Callback, class Iterator> ProjNode* apply_to_projs_any_iterator(Iterator i, Callback callback) const {
    for (; i.cont(); i.next()) {
      Node* p = i.current();
      if (p->is_Proj()) {
        ProjNode* proj = p->as_Proj();
        ApplyToProjs result = callback(proj);
        if (result == BREAK_AND_RETURN_CURRENT_PROJ) {
          return proj;
        }
        assert(result == CONTINUE, "should be either break or continue");
      } else {
        assert(p == this && is_Start(), "else must be proj");
      }
    }
    return nullptr;
  }
  enum ApplyToProjs {
    CONTINUE,
    BREAK_AND_RETURN_CURRENT_PROJ
  };

  // Run callback on projections with iterator passed as argument
  template <class Callback> ProjNode* apply_to_projs(DUIterator_Fast& imax, DUIterator_Fast& i, Callback callback, uint which_proj) const;

  // Same but with default iterator and for matching _con
  template<class Callback> ProjNode* apply_to_projs(Callback callback, uint which_proj) const {
    DUIterator_Fast imax, i = fast_outs(imax);
    return apply_to_projs(imax, i, callback, which_proj);
  }

  // Same but for matching _con and _is_io_use
  template <class Callback> ProjNode* apply_to_projs(Callback callback, uint which_proj, bool is_io_use) const;

public:
  template<class Callback> void for_each_proj(Callback callback, uint which_proj) const {
    auto callback_always_continue = [&](ProjNode* proj) {
      callback(proj);
      return MultiNode::CONTINUE;
    };
    apply_to_projs(callback_always_continue, which_proj);
  }

  template <class Callback> void for_each_proj(Callback callback, uint which_proj, bool is_io_use) const {
    auto callback_always_continue = [&](ProjNode* proj) {
      callback(proj);
      return MultiNode::CONTINUE;
    };
    apply_to_projs(callback_always_continue, which_proj, is_io_use);
  }


  ProjNode* find_first(uint which_proj) const;
  ProjNode* find_first(uint which_proj, bool is_io_use) const;
};

class BinaryMultiNode : public MultiNode {
protected:
  BinaryMultiNode(Node* ctrl, Node* in1, Node* in2) : MultiNode(3) {
    init_req(0, ctrl);
    init_req(1, in1);
    init_req(2, in2);
  }

public:
  enum {
    first_proj_num = 0,
    second_proj_num = 1
  };

  virtual Node* Identity(PhaseGVN* phase) { return this; }
  virtual Node* Ideal(PhaseGVN* phase, bool can_reshape) { return nullptr; }
  virtual const Type* Value(PhaseGVN* phase) const { return bottom_type(); }
  virtual uint hash() const { return Node::hash(); }
  virtual bool is_CFG() const { return false; }
  virtual uint ideal_reg() const { return NotAMachineReg; }

  ProjNode* first_proj() const { return proj_out_or_null(first_proj_num); }
  ProjNode* second_proj() const { return proj_out_or_null(second_proj_num); }

private:
  virtual bool depends_only_on_test() const { return false; }
};

//------------------------------ProjNode---------------------------------------
// This class defines a Projection node.  Projections project a single element
// out of a tuple (or Signature) type.  Only MultiNodes produce TypeTuple
// results.
class ProjNode : public Node {
protected:
  virtual uint hash() const;
  virtual bool cmp( const Node &n ) const;
  virtual uint size_of() const;
  void check_con() const;       // Called from constructor.
  const Type* proj_type(const Type* t) const;

public:
  ProjNode( Node *src, uint con, bool io_use = false )
    : Node( src ), _con(con), _is_io_use(io_use)
  {
    init_class_id(Class_Proj);
    // Optimistic setting. Need additional checks in Node::is_dead_loop_safe().
    if (con != TypeFunc::Memory || src->is_Start())
      init_flags(Flag_is_dead_loop_safe);
    DEBUG_ONLY(check_con());
  }
  const uint _con;              // The field in the tuple we are projecting
  const bool _is_io_use;        // Used to distinguish between the projections
                                // used on the control and io paths from a macro node
  virtual int Opcode() const;
  virtual bool is_CFG() const;
  virtual const Type *bottom_type() const;
  virtual const TypePtr *adr_type() const;
  virtual bool pinned() const;
  virtual Node* Identity(PhaseGVN* phase);
  virtual const Type* Value(PhaseGVN* phase) const;
  virtual uint ideal_reg() const;
  virtual const RegMask &out_RegMask() const;

#ifndef PRODUCT
  virtual void dump_spec(outputStream *st) const;
  virtual void dump_compact_spec(outputStream *st) const;
#endif

  // Return uncommon trap call node if proj is for "proj->[region->..]call_uct"
  // null otherwise
  CallStaticJavaNode* is_uncommon_trap_proj(Deoptimization::DeoptReason reason = Deoptimization::Reason_none) const;
  // Return uncommon trap call node for    "if(test)-> proj -> ...
  //                                                 |
  //                                                 V
  //                                             other_proj->[region->..]call_uct"
  // null otherwise
  CallStaticJavaNode* is_uncommon_trap_if_pattern(Deoptimization::DeoptReason reason = Deoptimization::Reason_none) const;
};

// A ProjNode variant that captures an adr_type(). Used as a projection of InitializeNode to have the right adr_type()
// for array elements/fields.
class NarrowMemProjNode : public ProjNode {
private:
  const TypePtr* const _adr_type;
protected:
  virtual uint hash() const {
    return ProjNode::hash() + _adr_type->hash();
  }
  virtual bool cmp(const Node& n) const {
    return ProjNode::cmp(n) && ((NarrowMemProjNode&)n)._adr_type == _adr_type;
  }
  virtual uint size_of() const {
    return sizeof(*this);
  }
public:
  NarrowMemProjNode(InitializeNode* src, const TypePtr* adr_type);

  virtual const TypePtr* adr_type() const {
    return _adr_type;
  }

  virtual int Opcode() const;
};

template <class Callback> ProjNode* MultiNode::apply_to_projs(DUIterator_Fast& imax, DUIterator_Fast& i, Callback callback, uint which_proj) const {
  auto filter = [&](ProjNode* proj) {
    if (proj->_con == which_proj && callback(proj) == BREAK_AND_RETURN_CURRENT_PROJ) {
      return BREAK_AND_RETURN_CURRENT_PROJ;
    }
    return CONTINUE;
  };
  return apply_to_projs_any_iterator(UsesIteratorFast(imax, i, this), filter);
}

/* Tuples are used to avoid manual graph surgery. When a node with Proj outputs (such as a call)
 * must be removed and its ouputs replaced by its input, or some other value, we can make its
 * ::Ideal return a tuple of what we want for each output: the ::Identity of output Proj will
 * take care to jump over the Tuple and directly pick up the right input of the Tuple.
 *
 * For instance, if a function call is proven to have no side effect and return the constant 0,
 * we can replace it with the 6-tuple:
 * (control input, IO input, memory input, frame ptr input, return addr input, Con:0)
 * all the output projections will pick up the input of the now gone call, except for the result
 * projection that is replaced by 0.
 *
 * Using TupleNode avoid manual graph surgery and leave that to our expert surgeon: IGVN.
 * Since the user of a Tuple are expected to be Proj, when creating a tuple during idealization,
 * the output Proj should be enqueued for IGVN immediately after, and the tuple should not survive
 * after the current IGVN.
 */
class TupleNode : public MultiNode {
  const TypeTuple* _tf;

  template <typename... NN>
  static void make_helper(TupleNode* tn, uint i, Node* node, NN... nn) {
    tn->set_req(i, node);
    make_helper(tn, i + 1, nn...);
  }

  static void make_helper(TupleNode*, uint) {}

public:
  TupleNode(const TypeTuple* tf) : MultiNode(tf->cnt()), _tf(tf) {}

  int Opcode() const override;
  const Type* bottom_type() const override { return _tf; }

  /* Give as many `Node*` as you want in the `nn` pack:
   * TupleNode::make(tf, input1)
   * TupleNode::make(tf, input1, input2, input3, input4)
   */
  template <typename... NN>
  static TupleNode* make(const TypeTuple* tf, NN... nn) {
    TupleNode* tn = new TupleNode(tf);
    make_helper(tn, 0, nn...);
    return tn;
  }
};

#endif // SHARE_OPTO_MULTNODE_HPP