/*

 * Copyright (c) 2009, 2015, 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.

 *

 */

#include "precompiled.hpp"

#include "compiler/compileLog.hpp"

#include "opto/addnode.hpp"

#include "opto/callGenerator.hpp"

#include "opto/callnode.hpp"

#include "opto/divnode.hpp"

#include "opto/graphKit.hpp"

#include "opto/idealKit.hpp"

#include "opto/rootnode.hpp"

#include "opto/runtime.hpp"

#include "opto/stringopts.hpp"

#include "opto/subnode.hpp"

#include "runtime/sharedRuntime.hpp"

#define __ kit.

class StringConcat : public ResourceObj {

 private:

  PhaseStringOpts*    _stringopts;

  Node*               _string_alloc;

  AllocateNode*       _begin;          // The allocation the begins the pattern

  CallStaticJavaNode* _end;            // The final call of the pattern.  Will either be

                                       // SB.toString or or String.<init>(SB.toString)

  bool                _multiple;       // indicates this is a fusion of two or more

                                       // separate StringBuilders

  Node*               _arguments;      // The list of arguments to be concatenated

  GrowableArray<int>  _mode;           // into a String along with a mode flag

                                       // indicating how to treat the value.

  Node_List           _constructors;   // List of constructors (many in case of stacked concat)

  Node_List           _control;        // List of control nodes that will be deleted

  Node_List           _uncommon_traps; // Uncommon traps that needs to be rewritten

                                       // to restart at the initial JVMState.

 public:

  // Mode for converting arguments to Strings

  enum {

    StringMode,

    IntMode,

    CharMode,

    StringNullCheckMode

  };

  StringConcat(PhaseStringOpts* stringopts, CallStaticJavaNode* end):

    _end(end),

    _begin(NULL),

    _multiple(false),

    _string_alloc(NULL),

    _stringopts(stringopts) {

    _arguments = new Node(1);

    _arguments->del_req(0);

  }

  bool validate_mem_flow();

  bool validate_control_flow();

  void merge_add() {

#if 0

    // XXX This is place holder code for reusing an existing String

    // allocation but the logic for checking the state safety is

    // probably inadequate at the moment.

    CallProjections endprojs;

    sc->end()->extract_projections(&endprojs, false);

    if (endprojs.resproj != NULL) {

      for (SimpleDUIterator i(endprojs.resproj); i.has_next(); i.next()) {

        CallStaticJavaNode *use = i.get()->isa_CallStaticJava();

        if (use != NULL && use->method() != NULL &&

            use->method()->intrinsic_id() == vmIntrinsics::_String_String &&

            use->in(TypeFunc::Parms + 1) == endprojs.resproj) {

          // Found useless new String(sb.toString()) so reuse the newly allocated String

          // when creating the result instead of allocating a new one.

          sc->set_string_alloc(use->in(TypeFunc::Parms));

          sc->set_end(use);

        }

      }

    }

#endif

  }

  StringConcat* merge(StringConcat* other, Node* arg);

  void set_allocation(AllocateNode* alloc) {

    _begin = alloc;

  }

  void append(Node* value, int mode) {

    _arguments->add_req(value);

    _mode.append(mode);

  }

  void push(Node* value, int mode) {

    _arguments->ins_req(0, value);

    _mode.insert_before(0, mode);

  }

  void push_string(Node* value) {

    push(value, StringMode);

  }

  void push_string_null_check(Node* value) {

    push(value, StringNullCheckMode);

  }

  void push_int(Node* value) {

    push(value, IntMode);

  }

  void push_char(Node* value) {

    push(value, CharMode);

  }

  static bool is_SB_toString(Node* call) {

    if (call->is_CallStaticJava()) {

      CallStaticJavaNode* csj = call->as_CallStaticJava();

      ciMethod* m = csj->method();

      if (m != NULL &&

          (m->intrinsic_id() == vmIntrinsics::_StringBuilder_toString ||

           m->intrinsic_id() == vmIntrinsics::_StringBuffer_toString)) {

        return true;

      }

    }

    return false;

  }

  static Node* skip_string_null_check(Node* value) {

    // Look for a diamond shaped Null check of toString() result

    // (could be code from String.valueOf()):

    // (Proj == NULL) ? "null":"CastPP(Proj)#NotNULL

    if (value->is_Phi()) {

      int true_path = value->as_Phi()->is_diamond_phi();

      if (true_path != 0) {

        // phi->region->if_proj->ifnode->bool

        BoolNode* b = value->in(0)->in(1)->in(0)->in(1)->as_Bool();

        Node* cmp = b->in(1);

        Node* v1 = cmp->in(1);

        Node* v2 = cmp->in(2);

        // Null check of the return of toString which can simply be skipped.

        if (b->_test._test == BoolTest::ne &&

            v2->bottom_type() == TypePtr::NULL_PTR &&

            value->in(true_path)->Opcode() == Op_CastPP &&

            value->in(true_path)->in(1) == v1 &&

            v1->is_Proj() && is_SB_toString(v1->in(0))) {

          return v1;

        }

      }

    }

    return value;

  }

  Node* argument(int i) {

    return _arguments->in(i);

  }

  Node* argument_uncast(int i) {

    Node* arg = argument(i);

    int amode = mode(i);

    if (amode == StringConcat::StringMode ||

        amode == StringConcat::StringNullCheckMode) {

      arg = skip_string_null_check(arg);

    }

    return arg;

  }

  void set_argument(int i, Node* value) {

    _arguments->set_req(i, value);

  }

  int num_arguments() {

    return _mode.length();

  }

  int mode(int i) {

    return _mode.at(i);

  }

  void add_control(Node* ctrl) {

    assert(!_control.contains(ctrl), "only push once");

    _control.push(ctrl);

  }

  void add_constructor(Node* init) {

    assert(!_constructors.contains(init), "only push once");

    _constructors.push(init);

  }

  CallStaticJavaNode* end() { return _end; }

  AllocateNode* begin() { return _begin; }

  Node* string_alloc() { return _string_alloc; }

  void eliminate_unneeded_control();

  void eliminate_initialize(InitializeNode* init);

  void eliminate_call(CallNode* call);

  void maybe_log_transform() {

    CompileLog* log = _stringopts->C->log();

    if (log != NULL) {

      log->head("replace_string_concat arguments='%d' string_alloc='%d' multiple='%d'",

                num_arguments(),

                _string_alloc != NULL,

                _multiple);

      JVMState* p = _begin->jvms();

      while (p != NULL) {

        log->elem("jvms bci='%d' method='%d'", p->bci(), log->identify(p->method()));

        p = p->caller();

      }

      log->tail("replace_string_concat");

    }

  }

  void convert_uncommon_traps(GraphKit& kit, const JVMState* jvms) {

    for (uint u = 0; u < _uncommon_traps.size(); u++) {

      Node* uct = _uncommon_traps.at(u);

      // Build a new call using the jvms state of the allocate

      address call_addr = SharedRuntime::uncommon_trap_blob()->entry_point();

      const TypeFunc* call_type = OptoRuntime::uncommon_trap_Type();

      const TypePtr* no_memory_effects = NULL;

      Compile* C = _stringopts->C;

      CallStaticJavaNode* call = new CallStaticJavaNode(call_type, call_addr, "uncommon_trap",

                                                        jvms->bci(), no_memory_effects);

      for (int e = 0; e < TypeFunc::Parms; e++) {

        call->init_req(e, uct->in(e));

      }

      // Set the trap request to record intrinsic failure if this trap

      // is taken too many times.  Ideally we would handle then traps by

      // doing the original bookkeeping in the MDO so that if it caused

      // the code to be thrown out we could still recompile and use the

      // optimization.  Failing the uncommon traps doesn't really mean

      // that the optimization is a bad idea but there's no other way to

      // do the MDO updates currently.

      int trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_intrinsic,

                                                           Deoptimization::Action_make_not_entrant);

      call->init_req(TypeFunc::Parms, __ intcon(trap_request));

      kit.add_safepoint_edges(call);

      _stringopts->gvn()->transform(call);

      C->gvn_replace_by(uct, call);

      uct->disconnect_inputs(NULL, C);

    }

  }

  void cleanup() {

    // disconnect the hook node

    _arguments->disconnect_inputs(NULL, _stringopts->C);

  }

};

void StringConcat::eliminate_unneeded_control() {

  for (uint i = 0; i < _control.size(); i++) {

    Node* n = _control.at(i);

    if (n->is_Allocate()) {

      eliminate_initialize(n->as_Allocate()->initialization());

    }

    if (n->is_Call()) {

      if (n != _end) {

        eliminate_call(n->as_Call());

      }

    } else if (n->is_IfTrue()) {

      Compile* C = _stringopts->C;

      C->gvn_replace_by(n, n->in(0)->in(0));

      // get rid of the other projection

      C->gvn_replace_by(n->in(0)->as_If()->proj_out(false), C->top());

    }

  }

}

StringConcat* StringConcat::merge(StringConcat* other, Node* arg) {

  StringConcat* result = new StringConcat(_stringopts, _end);

  for (uint x = 0; x < _control.size(); x++) {

    Node* n = _control.at(x);

    if (n->is_Call()) {

      result->_control.push(n);

    }

  }

  for (uint x = 0; x < other->_control.size(); x++) {

    Node* n = other->_control.at(x);

    if (n->is_Call()) {

      result->_control.push(n);

    }

  }

  assert(result->_control.contains(other->_end), "what?");

  assert(result->_control.contains(_begin), "what?");

  for (int x = 0; x < num_arguments(); x++) {

    Node* argx = argument_uncast(x);

    if (argx == arg) {

      // replace the toString result with the all the arguments that

      // made up the other StringConcat

      for (int y = 0; y < other->num_arguments(); y++) {

        result->append(other->argument(y), other->mode(y));

      }

    } else {

      result->append(argx, mode(x));

    }

  }

  result->set_allocation(other->_begin);

  for (uint i = 0; i < _constructors.size(); i++) {

    result->add_constructor(_constructors.at(i));

  }

  for (uint i = 0; i < other->_constructors.size(); i++) {

    result->add_constructor(other->_constructors.at(i));

  }

  result->_multiple = true;

  return result;

}

void StringConcat::eliminate_call(CallNode* call) {

  Compile* C = _stringopts->C;

  CallProjections projs;

  call->extract_projections(&projs, false);

  if (projs.fallthrough_catchproj != NULL) {

    C->gvn_replace_by(projs.fallthrough_catchproj, call->in(TypeFunc::Control));

  }

  if (projs.fallthrough_memproj != NULL) {

    C->gvn_replace_by(projs.fallthrough_memproj, call->in(TypeFunc::Memory));

  }

  if (projs.catchall_memproj != NULL) {

    C->gvn_replace_by(projs.catchall_memproj, C->top());

  }

  if (projs.fallthrough_ioproj != NULL) {

    C->gvn_replace_by(projs.fallthrough_ioproj, call->in(TypeFunc::I_O));

  }

  if (projs.catchall_ioproj != NULL) {

    C->gvn_replace_by(projs.catchall_ioproj, C->top());

  }

  if (projs.catchall_catchproj != NULL) {

    // EA can't cope with the partially collapsed graph this

    // creates so put it on the worklist to be collapsed later.

    for (SimpleDUIterator i(projs.catchall_catchproj); i.has_next(); i.next()) {

      Node *use = i.get();

      int opc = use->Opcode();

      if (opc == Op_CreateEx || opc == Op_Region) {

        _stringopts->record_dead_node(use);

      }

    }

    C->gvn_replace_by(projs.catchall_catchproj, C->top());

  }

  if (projs.resproj != NULL) {

    C->gvn_replace_by(projs.resproj, C->top());

  }

  C->gvn_replace_by(call, C->top());

}

void StringConcat::eliminate_initialize(InitializeNode* init) {

  Compile* C = _stringopts->C;

  // Eliminate Initialize node.

  assert(init->outcnt() <= 2, "only a control and memory projection expected");

  assert(init->req() <= InitializeNode::RawStores, "no pending inits");

  Node *ctrl_proj = init->proj_out(TypeFunc::Control);

  if (ctrl_proj != NULL) {

    C->gvn_replace_by(ctrl_proj, init->in(TypeFunc::Control));

  }

  Node *mem_proj = init->proj_out(TypeFunc::Memory);

  if (mem_proj != NULL) {

    Node *mem = init->in(TypeFunc::Memory);

    C->gvn_replace_by(mem_proj, mem);

  }

  C->gvn_replace_by(init, C->top());

  init->disconnect_inputs(NULL, C);

}

Node_List PhaseStringOpts::collect_toString_calls() {

  Node_List string_calls;

  Node_List worklist;

  _visited.Clear();

  // Prime the worklist

  for (uint i = 1; i < C->root()->len(); i++) {

    Node* n = C->root()->in(i);

    if (n != NULL && !_visited.test_set(n->_idx)) {

      worklist.push(n);

    }

  }

  while (worklist.size() > 0) {

    Node* ctrl = worklist.pop();

    if (StringConcat::is_SB_toString(ctrl)) {

      CallStaticJavaNode* csj = ctrl->as_CallStaticJava();

      string_calls.push(csj);

    }

    if (ctrl->in(0) != NULL && !_visited.test_set(ctrl->in(0)->_idx)) {

      worklist.push(ctrl->in(0));

    }

    if (ctrl->is_Region()) {

      for (uint i = 1; i < ctrl->len(); i++) {

        if (ctrl->in(i) != NULL && !_visited.test_set(ctrl->in(i)->_idx)) {

          worklist.push(ctrl->in(i));

        }

      }

    }

  }

  return string_calls;

}

StringConcat* PhaseStringOpts::build_candidate(CallStaticJavaNode* call) {

  ciMethod* m = call->method();

  ciSymbol* string_sig;

  ciSymbol* int_sig;

  ciSymbol* char_sig;

  if (m->holder() == C->env()->StringBuilder_klass()) {

    string_sig = ciSymbol::String_StringBuilder_signature();

    int_sig = ciSymbol::int_StringBuilder_signature();

    char_sig = ciSymbol::char_StringBuilder_signature();

  } else if (m->holder() == C->env()->StringBuffer_klass()) {

    string_sig = ciSymbol::String_StringBuffer_signature();

    int_sig = ciSymbol::int_StringBuffer_signature();

    char_sig = ciSymbol::char_StringBuffer_signature();

  } else {

    return NULL;

  }

#ifndef PRODUCT

  if (PrintOptimizeStringConcat) {

    tty->print("considering toString call in ");

    call->jvms()->dump_spec(tty); tty->cr();

  }

#endif

  StringConcat* sc = new StringConcat(this, call);

  AllocateNode* alloc = NULL;

  InitializeNode* init = NULL;

  // possible opportunity for StringBuilder fusion

  CallStaticJavaNode* cnode = call;

  while (cnode) {

    Node* recv = cnode->in(TypeFunc::Parms)->uncast();

    if (recv->is_Proj()) {

      recv = recv->in(0);

    }

    cnode = recv->isa_CallStaticJava();

    if (cnode == NULL) {

      alloc = recv->isa_Allocate();

      if (alloc == NULL) {

        break;

      }

      // Find the constructor call

      Node* result = alloc->result_cast();

      if (result == NULL || !result->is_CheckCastPP() || alloc->in(TypeFunc::Memory)->is_top()) {

        // strange looking allocation

#ifndef PRODUCT

        if (PrintOptimizeStringConcat) {

          tty->print("giving up because allocation looks strange ");

          alloc->jvms()->dump_spec(tty); tty->cr();

        }

#endif

        break;

      }

      Node* constructor = NULL;

      for (SimpleDUIterator i(result); i.has_next(); i.next()) {

        CallStaticJavaNode *use = i.get()->isa_CallStaticJava();

        if (use != NULL &&

            use->method() != NULL &&

            !use->method()->is_static() &&

            use->method()->name() == ciSymbol::object_initializer_name() &&

            use->method()->holder() == m->holder()) {

          // Matched the constructor.

          ciSymbol* sig = use->method()->signature()->as_symbol();

          if (sig == ciSymbol::void_method_signature() ||

              sig == ciSymbol::int_void_signature() ||

              sig == ciSymbol::string_void_signature()) {

            if (sig == ciSymbol::string_void_signature()) {

              // StringBuilder(String) so pick this up as the first argument

              assert(use->in(TypeFunc::Parms + 1) != NULL, "what?");

              const Type* type = _gvn->type(use->in(TypeFunc::Parms + 1));

              if (type == TypePtr::NULL_PTR) {

                // StringBuilder(null) throws exception.

#ifndef PRODUCT

                if (PrintOptimizeStringConcat) {

                  tty->print("giving up because StringBuilder(null) throws exception");

                  alloc->jvms()->dump_spec(tty); tty->cr();

                }

#endif

                return NULL;

              }

              // StringBuilder(str) argument needs null check.

              sc->push_string_null_check(use->in(TypeFunc::Parms + 1));

            }

            // The int variant takes an initial size for the backing

            // array so just treat it like the void version.

            constructor = use;

          } else {

#ifndef PRODUCT

            if (PrintOptimizeStringConcat) {

              tty->print("unexpected constructor signature: %s", sig->as_utf8());

            }

#endif

          }

          break;

        }

      }

      if (constructor == NULL) {

        // couldn't find constructor

#ifndef PRODUCT

        if (PrintOptimizeStringConcat) {

          tty->print("giving up because couldn't find constructor ");

          alloc->jvms()->dump_spec(tty); tty->cr();

        }

#endif