primInliner.cpp

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/* Copyright 1994 - 1996 LongView Technologies L.L.C. $Revision: 1.100 $ */
/* Copyright (c) 2006, Sun Microsystems, Inc.
All rights reserved.

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    * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
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# include "incls/_precompiled.incl"

# ifdef DELTA_COMPILER
# include "incls/_primInliner.cpp.incl"

inline bool equal(char* s, char* t) { return strcmp(s, t) == 0; }


void PrimInliner::assert_failure_block() {
  assert(_failure_block != NULL, "primitive must have a failure block");
}


void PrimInliner::assert_no_failure_block() {
  assert(_failure_block == NULL, "primitive doesn't have a failure block");
}


void PrimInliner::assert_receiver() {
  assert(parameter(0) == _scope->self(), "first parameter must be self");
}


int PrimInliner::log2(int x) const {
  int i = -1;
  int p =  1;
  while (p != 0 && p <= x) {
    // p = 2^(i+1) && p <= x (i.e., 2^(i+1) <= x)
    i++; p *= 2;
  }
  // p = 2^(i+1) && x < p (i.e., 2^i <= x < 2^(i+1))
  // (if p = 0 then overflow occured and i = 31)
  return i;
}


Expr* PrimInliner::tryConstantFold() {
  // Returns the result if the primitive call has been constant folded
  // successfully; returns NULL otherwise.
  // Note: The result may be a marked oop - which has to be unmarked
  // before using it - and which indicates that the primitive will fail
  // always.
  if (!_pdesc->can_be_constant_folded()) {
    // check for Symbol>>at: before declaring failure
    if ((equal(_pdesc->name(), "primitiveIndexedByteAt:ifFail:") ||
         equal(_pdesc->name(), "primitiveIndexedByteCharacterAt:ifFail:")) &&
        parameter(0)->hasKlass() && parameter(0)->klass() == Universe::symbolKlassObj()) {
      // the at: primitive can be constant-folded for symbols
      // what if the receiver is a constant string? unfortunately, Smalltalk has
      // "assignable constants" like Fortran...
    } else {
      return NULL;
    }
  }
  // get parameters
  int i = number_of_parameters();
  oop* args = NEW_RESOURCE_ARRAY(oop, i);
  while (i > 0) {
    i--;
    Expr* arg = parameter(i);
    if (!arg->isConstantExpr()) return NULL;
    args[i] = arg->constant();
  }
  // all parameters are constants, so call primitive
  oop res = _pdesc->eval(args);
  if (res->is_mark()) {
    // primitive failed
    return primitiveFailure(unmarkSymbol(res));
  } else if (res->is_mem() && !res->is_old()) {
    // must tenure result because nmethods aren't scavenged
    if (res->is_double()) {
      res = oopFactory::clone_double_to_oldspace(doubleOop(res));
    } else {
      // don't know how to tenure non-doubles
      warning("const folding: primitive %s is returning non-tenured object", _pdesc->name());
      return NULL;
    }
  }
  ConstPReg* constResult = new_ConstPReg(_scope, res);
  SAPReg* result = new SAPReg(_scope);
  _gen->append(NodeFactory::new_AssignNode(constResult, result));
  if (CompilerDebug) cout(PrintInlining)->print("%*sconstant-folding %s --> %#x\n", _scope->depth + 2, "", _pdesc->name(), res);
  assert(!constResult->constant->is_mark(), "result must not be marked");
  return new ConstantExpr(res, constResult, _gen->current());
}


Expr* PrimInliner::tryTypeCheck() {
  // Check if we have enough type information to prove that the primitive is going to fail;
  // if so, directly compile failure block (important for mixed-mode arithmetic).
  // Returns the failure result if the primitive call has been proven
  // to fail; returns NULL otherwise.
  // Should extend code to do general type compatibility test (including MergeExprs, e.g. for 
  // booleans) -- fix this later.  -Urs 11/95
  int num = number_of_parameters();
  for (int i = 0; i < num; i++) {
    Expr* a = parameter(i);
    if (a->hasKlass()) {
      Expr* primArgType = _pdesc->parameter_klass(i, a->preg(), NULL);
      if (primArgType && primArgType->hasKlass() && (a->klass() != primArgType->klass())) {
        // types differ -> primitive must fail
        return primitiveFailure(failureSymbolForArg(i));
      }
    }
  }
  return NULL;
}


symbolOop PrimInliner::failureSymbolForArg(int i) {
  assert(i >= 0 && i < number_of_parameters(), "bad index");
  switch (i) {
    case  0: return vmSymbols::receiver_has_wrong_type();
    case  1: return vmSymbols::first_argument_has_wrong_type();
    case  2: return vmSymbols::second_argument_has_wrong_type();
    case  3: return vmSymbols::third_argument_has_wrong_type();
    case  4: return vmSymbols::fourth_argument_has_wrong_type();
    case  5: return vmSymbols::fifth_argument_has_wrong_type();
    case  6: return vmSymbols::sixth_argument_has_wrong_type();
    case  7: return vmSymbols::seventh_argument_has_wrong_type();
    case  8: return vmSymbols::eighth_argument_has_wrong_type();
    case  9: return vmSymbols::ninth_argument_has_wrong_type();
    case 10: return vmSymbols::tenth_argument_has_wrong_type();
    default: return vmSymbols::argument_has_wrong_type();
  }
}


// Helper class to find the first assignment to a temporary in a failure
// block and the remaining method interval (without the assignment).
class AssignmentFinder: public SpecializedMethodClosure {
 public:
  int             tempNo;       // the temporary to which the assignment took place
  MethodInterval* block;        // the block over which to iterate
  MethodInterval* interval;     // the rest of the block without the assignment

  AssignmentFinder(MethodInterval* b) : SpecializedMethodClosure() {
    block = b;
    interval = NULL;
    MethodIterator iter(block, this);
  }
  void instruction()            { abort(); }
  void store_temporary(int no)  { 
    tempNo = no; 
    interval = MethodIterator::factory->new_MethodInterval(method(), NULL, next_bci(), block->end_bci()); 
  }
};


Expr* PrimInliner::primitiveFailure(symbolOop failureCode) {
  // compile a failing primitive
  if (CompilerDebug) cout(PrintInlining)->print("%*sprimitive %s will fail: %s\n", _scope->depth + 2, "", _pdesc->name(), failureCode->as_string());
  if (_failure_block == NULL) {
    error("\nPotential compiler bug: compiler believes primitive %s will fail\nwith error %s, but primitive has no failure block.\n",
          _pdesc->name(), failureCode->as_string());
    return NULL;
  }
  // The byte code compiler stores the primitive result in a temporary (= the parameter of
  // the inlined failure block).  Thus, we store res in the corresponding temp Expr so that
  // its value isn't forgotten (the default Expr for temps is UnknownExpr) and restore the
  // temp's original value afterwards. This is safe because within the failure block that
  // temporary is treated as a parameter and therefore is read-only.
  AssignmentFinder closure(_failure_block);
  assert(closure.interval != NULL, "no assignment found");
  Expr* old_temp = _scope->temporary(closure.tempNo);   // save temp
  Expr* res = new ConstantExpr(failureCode, new_ConstPReg(_scope, failureCode), _gen->current());
  _scope->set_temporary(closure.tempNo, res);
  closure.set_prim_failure(false);              // allow inlining sends in failure branch
  _gen->generate_subinterval(closure.interval, true);
  _scope->set_temporary(closure.tempNo, old_temp);
  return _gen->exprStack()->pop();              // restore temp
}

Expr* PrimInliner::merge_failure_block(Node* ok_exit, Expr* ok_result, Node* failure_exit, Expr* failure_code, bool ok_result_is_read_only) {
  assert(failure_code->hasKlass() && failure_code->klass() == Universe::symbolKlassObj(), "failure code must be a symbol");
  _cannotFail = false;
  // push failure code
  _gen->setCurrent(failure_exit);
  _gen->exprStack()->push(failure_code, _scope, failure_exit->bci());
  // code for failure block
  _gen->generate_subinterval(_failure_block, true);
  Expr* failure_block_result = _gen->exprStack()->pop();
  if (failure_block_result->isNoResultExpr()) {
    // failure doesn't reach here (e.g., uncommon branch)
    assert(!_gen->current() || _gen->current() == NodeBuilder::EndOfCode, "shouldn't reach here");
    _gen->setCurrent(ok_exit);
    return ok_result;
  } else {
    if (ok_result_is_read_only) {
      // cannot assign to ok_result directly => introduce extra PReg & extra assignment
      // (was bug detected with new backend: assignment to ok_result is not legal if it
      // refers to parameter/receiver of the method calling the primitive - gri 6/29/96)
      PReg* resPReg = new SAPReg(_scope);
      Node* node    = NodeFactory::new_AssignNode(ok_result->preg(), resPReg);
      Expr* resExpr = ok_result->shallowCopy(resPReg, node);
      ok_exit->append(node);
      ok_exit = node;
      ok_result = resExpr;
    }
    _gen->append(NodeFactory::new_AssignNode(failure_block_result->preg(), ok_result->preg()));
    // merge after failure block
    MergeNode* prim_exit = NodeFactory::new_MergeNode(_failure_block->end_bci());
    _gen->append(prim_exit);
    ok_exit->append(prim_exit);
    _gen->setCurrent(prim_exit);
    return new MergeExpr(ok_result, failure_block_result, ok_result->preg(), prim_exit);
  }
}

class PrimSendFinder : public SpecializedMethodClosure {
public:
  RScope* rs;
  bool was_executed;

  PrimSendFinder(RScope* rs)                    { this->rs = rs; was_executed = false; rs->extend(); }
  virtual void normal_send(InterpretedIC* ic)   { check_send(ic); }
  virtual void self_send  (InterpretedIC* ic)   { check_send(ic); }
  virtual void super_send (InterpretedIC* ic)   { check_send(ic); }
  void check_send(InterpretedIC* ic) {
    GrowableArray<RScope*>* sub = rs->subScopes(bci());
    if (sub->length() == 1 && sub->first()->isUntakenScope()) {
      // this send was never taken
    } else {
      was_executed = true;                      // this send was taken in recompilee
    }
  }
};


inline bool PrimInliner::basic_shouldUseUncommonTrap() const {
  ResourceMark rm;
  if (!theCompiler->useUncommonTraps) return false; 
  // first check if recompilee has a taken uncommon branch 
  // NOTE: the uncommon branch should be at _failure_block->begin_bci(), not _bci, but
  // deoptimization currently breaks if that's so -- please fix this, Lars
  // (search for new_UncommonNode below when fixing it)
  if (_scope->rscope->isNotUncommonAt(_bci)) return false;
  //if (_scope->rscope->isNotUncommonAt(_failure_block->begin_bci())) return false;
  if (_scope->rscope->isUncommonAt(_bci)) return true;
  //if (_scope->rscope->isUncommonAt(_failure_block->begin_bci())) return true;
  // now check if recompilee had code for the failure block, and any send in it was taken
  if (!_scope->rscope->get_nmethod()) {
    return true;      // if it's not compiled, assume that using uncommon branch is ok
  }
#ifdef broken
  // This code doesn't really do the right thing; what's needed is something that
  // can determine whether the failure was taken in the previous version of compiled code.
  // If there's a send that's easy (ic dirty flag), but if everything in the failure block
  // was inlined...?  Could put a "removable trap" there to determine this.  fix this later
  // -Urs 8/96
  PrimSendFinder p(_scope->rscope);
  MethodIterator it(_failure_block, &p);
  return !p.was_executed;
#endif
  // for now, try the aggressive approach: no proof that it was taken, so guess that it's uncommon
  return true;
}

bool PrimInliner::shouldUseUncommonTrap() {
  // remember result of call in _usingUncommonTrap
  _usingUncommonTrap = basic_shouldUseUncommonTrap(); 
  return _usingUncommonTrap;
}

Expr* PrimInliner::smi_ArithmeticOp(ArithOpCode op, Expr* arg1, Expr* arg2) {
  assert_failure_block();
  assert_receiver();
  
  // parameters & result registers
  bool       intArg1      = arg1->is_smi();
  bool       intArg2      = arg2->is_smi();
  bool       intBoth      = intArg1 && intArg2;                 // if true, tag error cannot occur
  SAPReg*    resPReg      = new SAPReg(_scope);                 // holds the result if primitive didn't fail
  SAPReg*    errPReg      = new SAPReg(_scope);                 // holds the error message if primitive failed
  MergeNode* failureStart = NodeFactory::new_MergeNode(_failure_block->begin_bci());

  // n1: operation & treatment of tag error
  Node* n1;
  AssignNode*  n1Err;
  ConstantExpr* n1Expr = NULL;
  if (intBoth) {
    // tag error cannot occur
    n1 = NodeFactory::new_ArithRRNode(resPReg, arg1->preg(), op, arg2->preg());
  } else {
    // tag error can occur
    n1 = NodeFactory::new_TArithRRNode(resPReg, arg1->preg(), op, arg2->preg(), intArg1, intArg2);
    if (shouldUseUncommonTrap()) {
      // simply jump to uncommon branch code
      n1->append(1, failureStart);
    } else {
      ConstPReg* n1PReg = new_ConstPReg(_scope, vmSymbols::first_argument_has_wrong_type());
      n1Err = NodeFactory::new_AssignNode(n1PReg, errPReg);
      n1Expr = new ConstantExpr(n1PReg->constant, errPReg, n1Err);
      n1->append(1, n1Err);
      n1Err->append(failureStart);
    }
  }
  _gen->append(n1);
  Expr* result = new KlassExpr(smiKlassObj, resPReg, n1);

  // n2: overflow check & treatment of overflow
  const bool taken_is_uncommon = true;
  BranchNode* n2 = NodeFactory::new_BranchNode(VSBranchOp, taken_is_uncommon);
  AssignNode* n2Err;
  ConstantExpr* n2Expr = NULL;
  if (shouldUseUncommonTrap()) {
    // simply jump to uncommon branch code
    n2->append(1, failureStart);
  } else {
    ConstPReg* n2PReg = new_ConstPReg(_scope, vmSymbols::smi_overflow());
    n2Err = NodeFactory::new_AssignNode(n2PReg, errPReg);
    n2Expr = new ConstantExpr(n2PReg->constant, errPReg, n2Err);
    n2->append(1, n2Err);
    n2Err->append(failureStart);
  }
  _gen->append(n2);

  // continuation
  if (shouldUseUncommonTrap()) {
    // uncommon branch instead of failure code
    failureStart->append(NodeFactory::new_UncommonNode(_gen->copyCurrentExprStack(), _bci /*_failure_block->begin_bci()*/));
  } else {
    assert(n2Expr != NULL, "no error message defined");
    Expr* error;
    if (n1Expr != NULL) {
      error = new MergeExpr(n1Expr, n2Expr, errPReg, failureStart);
    } else {
      error = n2Expr;
    }
    result = merge_failure_block(n2, result, failureStart, error, false);
  }
  return result;
}


Expr* PrimInliner::smi_BitOp(ArithOpCode op, Expr* arg1, Expr* arg2) {
  assert_failure_block();
  assert_receiver();

  // parameters & result registers
  bool    intArg1 = arg1->is_smi();
  bool    intArg2 = arg2->is_smi();
  bool    intBoth = intArg1 && intArg2; // if true, tag error cannot occur
  SAPReg* resPReg = new SAPReg(_scope); // holds the result if primitive didn't fail
  SAPReg* errPReg = new SAPReg(_scope); // holds the error message if primitive failed

  // n1: operation & treatment of tag error
  Node*  n1;
  AssignNode* n1Err;
  ConstantExpr* n1Expr;
  if (intBoth) {
    // tag error cannot occur
    n1 = NodeFactory::new_ArithRRNode(resPReg, arg1->preg(), op, arg2->preg());
  } else {
    // tag error can occur
    n1 = NodeFactory::new_TArithRRNode(resPReg, arg1->preg(), op, arg2->preg(), intArg1, intArg2);
    ConstPReg* n1PReg = new_ConstPReg(_scope, vmSymbols::first_argument_has_wrong_type());
    n1Err = NodeFactory::new_AssignNode(n1PReg, errPReg);
    n1Expr = new ConstantExpr(n1PReg->constant, errPReg, n1Err);
    n1->append(1, n1Err);
  }
  _gen->append(n1);

  // continuation
  Expr* result = new KlassExpr(smiKlassObj, resPReg, n1);
  if (!intBoth) {
    // failure can occur
    if (shouldUseUncommonTrap()) {
      // simply do an uncommon trap
      n1Err->append(NodeFactory::new_UncommonNode(_gen->copyCurrentExprStack(), _bci /*_failure_block->begin_bci()*/));
    } else {
      // treat failure case
      result = merge_failure_block(n1, result, n1Err, n1Expr, false);
    }
  }
  return result;
}


Expr* PrimInliner::smi_Div(Expr* x, Expr* y) {
  if (y->preg()->isConstPReg()) {
    assert(y->is_smi(), "type check should have failed");
    int d = smiOop(((ConstPReg*)y->preg())->constant)->value();
    if (is_power_of_2(d)) {
      // replace it with shift
      ConstPReg* preg = new_ConstPReg(_scope, as_smiOop(-log2(d)));
      return smi_BitOp(tShiftArithOp, x, new ConstantExpr(preg->constant, preg, _gen->_current));
    }
  }
  // otherwise leave it alone
  return NULL;
}


Expr* PrimInliner::smi_Mod(Expr* x, Expr* y) {
  if (y->preg()->isConstPReg()) {
    assert(y->is_smi(), "type check should have failed");
    int d = smiOop(((ConstPReg*)y->preg())->constant)->value();
    if (is_power_of_2(d)) {
      // replace it with mask
      ConstPReg* preg = new_ConstPReg(_scope, as_smiOop(d-1));
      return smi_BitOp(tAndArithOp, x, new ConstantExpr(preg->constant, preg, _gen->_current));
    }
  }
  // otherwise leave it alone
  return NULL;
}


Expr* PrimInliner::smi_Shift(Expr* arg1, Expr* arg2) {
  if (parameter(1)->preg()->isConstPReg()) {
    // inline if the shift count is a constant
    assert(arg2->is_smi(), "type check should have failed");
    return smi_BitOp(tShiftArithOp, arg1, arg2);
  }
  // otherwise leave it alone
  return NULL;
}


static BranchOpCode not(BranchOpCode cond) {
  switch (cond) {
    case EQBranchOp : return NEBranchOp;
    case NEBranchOp : return EQBranchOp;
    case LTBranchOp : return GEBranchOp;
    case LEBranchOp : return GTBranchOp;
    case GTBranchOp : return LEBranchOp;
    case GEBranchOp : return LTBranchOp;
    case LTUBranchOp: return GEUBranchOp;
    case LEUBranchOp: return GTUBranchOp;
    case GTUBranchOp: return LEUBranchOp;
    case GEUBranchOp: return LTUBranchOp;
    case VSBranchOp : return VCBranchOp;
    case VCBranchOp : return VSBranchOp;
  }
  ShouldNotReachHere();
  return EQBranchOp;
}


Expr* PrimInliner::generate_cond(BranchOpCode cond, NodeBuilder* gen, PReg* resPReg) {
// generate code loading true or false depending on current condition code
// Note: condition is negated in order to provoke a certain code order
//       when compiling whileTrue loops - gri 6/26/96

  // n2: conditional branch
  BranchNode* n2 = NodeFactory::new_BranchNode(not(cond));
  gen->append(n2);

  // tAsgn: true branch
  ConstPReg* tPReg = new_ConstPReg(gen->scope(), trueObj);
  AssignNode* tAsgn = NodeFactory::new_AssignNode(tPReg, resPReg);
  ConstantExpr* tExpr = new ConstantExpr(trueObj, resPReg, tAsgn);
  n2->append(0, tAsgn);

  // fAsgn: false branch
  ConstPReg* fPReg = new_ConstPReg(gen->scope(), falseObj);
  AssignNode* fAsgn = NodeFactory::new_AssignNode(fPReg, resPReg);
  ConstantExpr* fExpr = new ConstantExpr(falseObj, resPReg, fAsgn);
  n2->append(1, fAsgn);

  // ftm: false & true branch merger
  MergeNode* ftm = NodeFactory::new_MergeNode(fAsgn, tAsgn);
  Expr* result = new MergeExpr(fExpr, tExpr, resPReg, ftm);
  gen->setCurrent(ftm);
  return result;
}


Expr* PrimInliner::smi_Comparison(BranchOpCode cond, Expr* arg1, Expr* arg2) {
  assert_failure_block();
  assert_receiver();

  // parameters & result registers
  bool    intArg1 = arg1->is_smi();
  bool    intArg2 = arg2->is_smi();
  bool    intBoth = intArg1 && intArg2; // if true, tag error cannot occur
  SAPReg* resPReg = new SAPReg(_scope); // holds the result if primitive didn't fail
  SAPReg* errPReg = new SAPReg(_scope); // holds the error message if primitive failed

  // n1: comparison & treatment of tag error
  Node* n1;
  ConstPReg* n1PReg;
  AssignNode* n1Err;
  ConstantExpr* n1Expr;
  if (intBoth) {
    // tag error cannot occur
    n1 = NodeFactory::new_ArithRRNode(new NoPReg(_scope), arg1->preg(), tCmpArithOp, arg2->preg());
  } else {
    // tag error can occur
    n1 = NodeFactory::new_TArithRRNode(new NoPReg(_scope), arg1->preg(), tCmpArithOp, arg2->preg(), intArg1, intArg2);
    n1PReg = new_ConstPReg(_scope, vmSymbols::first_argument_has_wrong_type());
    n1Err = NodeFactory::new_AssignNode(n1PReg, errPReg);
    n1Expr = new ConstantExpr(n1PReg->constant, errPReg, n1Err);
    n1->append(1, n1Err);
  }
  _gen->append(n1);

  Expr* result = generate_cond(cond, _gen, resPReg);

  // continuation
  if (!intBoth) {
    // failure can occur
    if (shouldUseUncommonTrap()) {
      // simply do an uncommon trap
      n1Err->append(NodeFactory::new_UncommonNode(_gen->copyCurrentExprStack(), _bci /*_failure_block->begin_bci()*/));
    } else {
      // treat failure case
      result = merge_failure_block(result->node(), result, n1Err, n1Expr, false);
    }
  }
  return result;
}


Expr* PrimInliner::array_size() {
  assert(_failure_block == NULL, "primitive must have no failure block");
  assert_receiver();

  // parameters & result registers
  Expr*  array = parameter(0);
  Klass* klass = array->klass()->klass_part();
  int    lenOffs = klass->non_indexable_size();

  // get size
  SAPReg* res = new SAPReg(_scope);
  _gen->append(NodeFactory::new_LoadOffsetNode(res, array->preg(), lenOffs, true));
  return new KlassExpr(smiKlassObj, res, _gen->_current);
}


Expr* PrimInliner::array_at_ifFail(ArrayAtNode::AccessType access_type) {
  assert_failure_block();
  assert_receiver();

  // parameters & result registers
  Expr*   array    = parameter(0);
  Expr*   index    = parameter(1);
  SAPReg* resPReg  = new SAPReg(_scope);        // holds the result if primitive didn't fail
  SAPReg* errPReg  = new SAPReg(_scope);        // holds the error message if primitive failed
  Klass*  klass    = array->klass()->klass_part();
  int     lenOffs  = klass->non_indexable_size();
  int     arrOffs  = lenOffs + 1;
  
  // at node
  ArrayAtNode* at = NodeFactory::new_ArrayAtNode(
    access_type, array->preg(), index->preg(), index->is_smi(), resPReg, errPReg, arrOffs, lenOffs
  );
  _gen->append(at);

  // continuation
  Expr* resExpr;
  switch (access_type) {
    case ArrayAtNode::byte_at       : // fall through
    case ArrayAtNode::double_byte_at: resExpr = new KlassExpr(Universe::smiKlassObj(), resPReg, at);            break;
    case ArrayAtNode::character_at  : resExpr = new KlassExpr(Universe::characterKlassObj(), resPReg, at);      break;
    case ArrayAtNode::object_at     : resExpr = new UnknownExpr(resPReg, at);                                   break;
    default                         : ShouldNotReachHere();
  }
  if (at->canFail()) {
    if (shouldUseUncommonTrap()) {
      // uncommon branch instead of failure code
      at->append(1, NodeFactory::new_UncommonNode(_gen->copyCurrentExprStack(), _bci /*_failure_block->begin_bci()*/));
    } else {
      // append failure code
      NopNode* err = NodeFactory::new_NopNode();
      at->append(1, err);
      Expr* errExpr = new KlassExpr(Universe::symbolKlassObj(), errPReg, at);
      resExpr = merge_failure_block(at, resExpr, err, errExpr, false);
    }
  }
  return resExpr;
}


Expr* PrimInliner::array_at_put_ifFail(ArrayAtPutNode::AccessType access_type) {
  assert_failure_block();
  assert_receiver();

  // parameters & result registers
  Expr*   array      = parameter(0);
  Expr*   index      = parameter(1);
  Expr*   element    = parameter(2);
  SAPReg* resPReg    = new SAPReg(_scope);      // holds the result if primitive didn't fail
  SAPReg* errPReg    = new SAPReg(_scope);      // holds the error message if primitive failed
  Klass*  klass      = array->klass()->klass_part();
  int     lenOffs    = klass->non_indexable_size();
  int     arrOffs    = lenOffs + 1;
  bool    storeCheck = (access_type == ArrayAtPutNode::object_at_put) && element->needsStoreCheck();
  
  if (access_type == ArrayAtPutNode::object_at_put) {
    // make sure blocks stored into array are created
    _gen->materialize(element->preg(), NULL);
  }

  // atPut node
  ArrayAtPutNode* atPut = NodeFactory::new_ArrayAtPutNode(
    access_type, array->preg(), index->preg(), index->is_smi(), element->preg(), element->is_smi(), NULL, errPReg, arrOffs, lenOffs, storeCheck
  );
  _gen->append(atPut);

  // continuation
  Expr* resExpr = array;
  if (atPut->canFail()) {
    if (shouldUseUncommonTrap()) {
      // uncommon branch instead of failure code
      atPut->append(1, NodeFactory::new_UncommonNode(_gen->copyCurrentExprStack(), _bci /*_failure_block->begin_bci()*/));
    } else {
      // append failure code
      NopNode* err = NodeFactory::new_NopNode();
      atPut->append(1, err);
      Expr* errExpr = new KlassExpr(Universe::symbolKlassObj(), errPReg, atPut);
      resExpr = merge_failure_block(atPut, resExpr, err, errExpr, true);
    }
  }
  return resExpr;
}


Expr* PrimInliner::obj_new() {
  // replace generic allocation primitive by size-specific primitive, if possible
  Expr* rcvr = parameter(0);
  if (!rcvr->isConstantExpr() || !rcvr->constant()->is_klass()) return NULL;
  Klass* klass = klassOop(rcvr->constant())->klass_part();      // class being instantiated
  if (klass->oop_is_indexable()) return NULL;                   // would fail (extremely unlikely)
  int size = klass->non_indexable_size();                       // size in words

  if (klass->can_inline_allocation()) {
    // These special compiler primitives only work for memOop klasses
    int number_of_instance_variables = size - memOopDesc::header_size();
    switch (number_of_instance_variables) {
      case 0: _pdesc = primitives::new0(); break;
      case 1: _pdesc = primitives::new1(); break;
      case 2: _pdesc = primitives::new2(); break;
      case 3: _pdesc = primitives::new3(); break;
      case 4: _pdesc = primitives::new4(); break;
      case 5: _pdesc = primitives::new5(); break;
      case 6: _pdesc = primitives::new6(); break;
      case 7: _pdesc = primitives::new7(); break;
      case 8: _pdesc = primitives::new8(); break;
      case 9: _pdesc = primitives::new9(); break;
      default:  ; // use generic primitives
    }
  }
  Expr* u = genCall(false);
  return new KlassExpr(klass->as_klassOop(), u->preg(), u->node());
}


Expr* PrimInliner::obj_shallowCopy() {
  // temporary hack, fix when prims have type info
  // Fix this Robert, 10/24-95, Lars
  Expr* u = genCall(false);
  assert(u->isUnknownExpr(), "oops");
  return new KlassExpr(parameter(0)->klass(), u->preg(), u->node());
}


Expr* PrimInliner::obj_equal() {
  assert_no_failure_block();

  // parameters & result registers
  PReg* arg1 = parameter(0)->preg();
  PReg* arg2 = parameter(1)->preg();
  // comparison
  _gen->append(NodeFactory::new_ArithRRNode(new NoPReg(_scope), arg1, CmpArithOp, arg2));
  SAPReg* resPReg = new SAPReg(_scope);
  return generate_cond(EQBranchOp, _gen, resPReg);
}


Expr* PrimInliner::obj_class(bool has_receiver) {
  assert_no_failure_block();
  if (has_receiver) assert_receiver();

  Expr*   obj     = parameter(0);
  if (obj->hasKlass()) {
    // constant-fold it
    klassOop k = obj->klass();
    return new ConstantExpr(k, new_ConstPReg(_scope, k), NULL);
  } else {
    SAPReg* resPReg = new SAPReg(_scope);
    InlinedPrimitiveNode* n = NodeFactory::new_InlinedPrimitiveNode(
      InlinedPrimitiveNode::obj_klass, resPReg, NULL, obj->preg()
    );
    _gen->append(n);
    // don't know exactly what it is - just use PIC info
    return new UnknownExpr(resPReg, n);
  }
}


Expr* PrimInliner::obj_hash(bool has_receiver) {
  assert_no_failure_block();
  if (has_receiver) assert_receiver();

  Expr* obj = parameter(0);
  if (obj->is_smi()) {
    // hash value = self (no code necessary)
    return obj;
  } else {
    return NULL;
    //
    // code in x86_node.cpp not yet implemented - fix this at some point
    //
    // has value taken from header field
    SAPReg* resPReg = new SAPReg(_scope);
    InlinedPrimitiveNode* n = NodeFactory::new_InlinedPrimitiveNode(
      InlinedPrimitiveNode::obj_hash, resPReg, NULL, obj->preg()
    );
    _gen->append(n);
    return new KlassExpr(Universe::smiKlassObj(), resPReg, n);
  }
}


Expr* PrimInliner::proxy_byte_at() {
  assert_failure_block();
  assert_receiver();

  // parameters & result registers
  Expr*   proxy     = parameter(0);
  Expr*   index     = parameter(1);
  SAPReg* resPReg   = new SAPReg(_scope);       // holds the result if primitive didn't fail
  SAPReg* errPReg   = new SAPReg(_scope);       // holds the error message if primitive failed
  
  // at node
  InlinedPrimitiveNode* at = NodeFactory::new_InlinedPrimitiveNode(
    InlinedPrimitiveNode::proxy_byte_at, resPReg, errPReg, proxy->preg(), index->preg(), index->is_smi()
  );
  _gen->append(at);

  // continuation
  Expr* resExpr = new KlassExpr(Universe::smiKlassObj(), resPReg, at);
  if (at->canFail()) {
    if (shouldUseUncommonTrap()) {
      // uncommon branch instead of failure code
      at->append(1, NodeFactory::new_UncommonNode(_gen->copyCurrentExprStack(), _bci /*_failure_block->begin_bci()*/));
    } else {
      // append failure code
      NopNode* err = NodeFactory::new_NopNode();
      at->append(1, err);
      Expr* errExpr = new KlassExpr(Universe::symbolKlassObj(), errPReg, at);
      resExpr = merge_failure_block(at, resExpr, err, errExpr, false);
    }
  }
  return resExpr;
}


Expr* PrimInliner::proxy_byte_at_put() {
  assert_failure_block();
  assert_receiver();

  // parameters & result registers
  Expr*   proxy     = parameter(0);
  Expr*   index     = parameter(1);
  Expr*   value     = parameter(2);
  SAPReg* errPReg   = new SAPReg(_scope);       // holds the error message if primitive failed
  
  // atPut node
  InlinedPrimitiveNode* atPut = NodeFactory::new_InlinedPrimitiveNode(
    InlinedPrimitiveNode::proxy_byte_at_put, NULL, errPReg, proxy->preg(), index->preg(), index->is_smi(), value->preg(), value->is_smi()
  );
  _gen->append(atPut);

  // continuation
  Expr* resExpr = proxy;
  if (atPut->canFail()) {
    if (shouldUseUncommonTrap()) {
      // uncommon branch instead of failure code
      atPut->append(1, NodeFactory::new_UncommonNode(_gen->copyCurrentExprStack(), _bci /*_failure_block->begin_bci()*/));
    } else {
      // append failure code
      NopNode* err = NodeFactory::new_NopNode();
      atPut->append(1, err);
      Expr* errExpr = new KlassExpr(Universe::symbolKlassObj(), errPReg, atPut);
      resExpr = merge_failure_block(atPut, resExpr, err, errExpr, true);
    }
  }
  return resExpr;
}


Expr* PrimInliner::block_primitiveValue() {
  PReg* r = parameter(0)->preg();
  if (r->isBlockPReg()) {
    // we know the identity of the block -- inline it if possible
    Inliner* inliner = _gen->inliner();
    SendInfo* info = new SendInfo(_scope, parameter(0), _pdesc->selector());
    Expr* res = inliner->inlineBlockInvocation(info);
    if (res) return res;
  } 
  // could at least inline block invocation -- fix this later
  return NULL;
}


Expr* PrimInliner::tryInline() {
  // Returns the failure result or the result of the primitive (if the
  // primitive can't fail) if the primitive has been inlined; returns
  // NULL otherwise. If the primitive has been inlined but can't fail,
  // the bci in the MethodDecoder is set to the first instruction after
  // the failure block.
  // NB: The comparisons below should be replaced with pointer comparisons
  // comparing with the appropriate vmSymbol. Should fix this at some point.
  char* name  = _pdesc->name();
  Expr* res = NULL;
  switch (_pdesc->group()) {
    case IntArithmeticPrimitive:
      if (number_of_parameters() == 2) {
        Expr* x = parameter(0);
        Expr* y = parameter(1);
        if (equal(name, "primitiveAdd:ifFail:"))                        { res = smi_ArithmeticOp(tAddArithOp, x, y);    break; }
        if (equal(name, "primitiveSubtract:ifFail:"))                   { res = smi_ArithmeticOp(tSubArithOp, x, y);    break; }
        if (equal(name, "primitiveMultiply:ifFail:"))                   { res = smi_ArithmeticOp(tMulArithOp, x, y);    break; }
        if (equal(name, "primitiveDiv:ifFail:"))                        { res = smi_Div(x, y);                          break; }
        if (equal(name, "primitiveMod:ifFail:"))                        { res = smi_Mod(x, y);                          break; }
        if (equal(name, "primitiveBitAnd:ifFail:"))                     { res = smi_BitOp(tAndArithOp, x, y);           break; }
        if (equal(name, "primitiveBitOr:ifFail:"))                      { res = smi_BitOp(tOrArithOp , x, y);           break; }
        if (equal(name, "primitiveBitXor:ifFail:"))                     { res = smi_BitOp(tXOrArithOp, x, y);           break; }
        if (equal(name, "primitiveRawBitShift:ifFail:"))                { res = smi_Shift(x, y);                        break; }
      }
      break;
    case IntComparisonPrimitive:
      if (number_of_parameters() == 2) {
        Expr* x = parameter(0);
        Expr* y = parameter(1);
        if (equal(name, "primitiveSmallIntegerEqual:ifFail:"))          { res = smi_Comparison(EQBranchOp, x, y);       break; }
        if (equal(name, "primitiveSmallIntegerNotEqual:ifFail:"))       { res = smi_Comparison(NEBranchOp, x, y);       break; }
        if (equal(name, "primitiveLessThan:ifFail:"))                   { res = smi_Comparison(LTBranchOp, x, y);       break; }
        if (equal(name, "primitiveLessThanOrEqual:ifFail:"))            { res = smi_Comparison(LEBranchOp, x, y);       break; }
        if (equal(name, "primitiveGreaterThan:ifFail:"))                { res = smi_Comparison(GTBranchOp, x, y);       break; }
        if (equal(name, "primitiveGreaterThanOrEqual:ifFail:"))         { res = smi_Comparison(GEBranchOp, x, y);       break; }
      }
      break;
    case FloatArithmeticPrimitive:
      break;
    case FloatComparisonPrimitive:
      break;
    case ObjArrayPrimitive:
      if (equal(name, "primitiveIndexedObjectSize"))                    { res = array_size();                                           break; }
      if (equal(name, "primitiveIndexedObjectAt:ifFail:"))              { res = array_at_ifFail(ArrayAtNode::object_at);                break; }
      if (equal(name, "primitiveIndexedObjectAt:put:ifFail:"))          { res = array_at_put_ifFail(ArrayAtPutNode::object_at_put);     break; }
      break;
    case ByteArrayPrimitive:
      if (equal(name, "primitiveIndexedByteSize"))                      { res = array_size();                                           break; }
      if (equal(name, "primitiveIndexedByteAt:ifFail:"))                { res = array_at_ifFail(ArrayAtNode::byte_at);                  break; }
      if (equal(name, "primitiveIndexedByteAt:put:ifFail:"))            { res = array_at_put_ifFail(ArrayAtPutNode::byte_at_put);       break; }
      break;
    case DoubleByteArrayPrimitive:
      if (equal(name, "primitiveIndexedDoubleByteSize"))                { res = array_size();                                           break; }
      if (equal(name, "primitiveIndexedDoubleByteAt:ifFail:"))          { res = array_at_ifFail(ArrayAtNode::double_byte_at);           break; }
      if (equal(name, "primitiveIndexedDoubleByteCharacterAt:ifFail:")) { res = array_at_ifFail(ArrayAtNode::character_at);             break; }
      if (equal(name, "primitiveIndexedDoubleByteAt:put:ifFail:"))      { res = array_at_put_ifFail(ArrayAtPutNode::double_byte_at_put);break; }
      break;
    case BlockPrimitive:
      if (strncmp(name, "primitiveValue", 14) == 0)                     { res = block_primitiveValue();         break; }
      break;
    case NormalPrimitive:
      if (strncmp(name, "primitiveNew", 12) == 0)                       { res = obj_new();                      break; }
      if (equal(name, "primitiveShallowCopyIfFail:ifFail:"))            { res = obj_shallowCopy();              break; }
      if (equal(name, "primitiveEqual:"))                               { res = obj_equal();                    break; }
      if (equal(name, "primitiveClass"))                                { res = obj_class(true);                break; }
      if (equal(name, "primitiveClassOf:"))                             { res = obj_class(false);               break; }
      if (equal(name, "primitiveHash"))                                 { res = obj_hash(true);                 break; }
      if (equal(name, "primitiveHashOf:"))                              { res = obj_hash(false);                break; }
      if (equal(name, "primitiveProxyByteAt:ifFail:"))                  { res = proxy_byte_at();                break; }
      if (equal(name, "primitiveProxyByteAt:put:ifFail:"))              { res = proxy_byte_at_put();            break; }
      break;
   default:
      fatal1("bad primitive group %d", _pdesc->group());
      break;
  }
 
  if (CompilerDebug) {
    cout(PrintInlining && (res != NULL))->print("%*sinlining %s %s\n", _scope->depth + 2, "", _pdesc->name(),
                                                _usingUncommonTrap ? "(unc. failure)" : (_cannotFail ? "(cannot fail)" :  ""));
  }
  if (!_usingUncommonTrap && !_cannotFail) theCompiler->reporter->report_prim_failure(_pdesc);
  return res;
}


PrimInliner::PrimInliner(NodeBuilder* gen, primitive_desc* pdesc, MethodInterval* failure_block) {
  assert(pdesc, "must have a primitive desc to inline");
  _gen          = gen;
  _pdesc        = pdesc;
  _failure_block= failure_block;

  _scope        = gen->_scope;
  _bci          = gen->bci();     // bci of primitive call
  _exprStack    = gen->_exprStack;
  _cannotFail   = true;
  _params       = new GrowableArray<Expr*>(number_of_parameters(), number_of_parameters(), NULL);
  _usingUncommonTrap = false;

  // get parameters
  int i = number_of_parameters();
  int first = _exprStack->length() - i;
  while (i-- > 0) {
    _params->at_put(i, _exprStack->at(first + i));
  }

  assert(_pdesc->can_fail() == (failure_block != NULL), "primitive desc & primitive usage inconsistent");
}


void PrimInliner::generate() {
  Expr* res = NULL;
  if (InlinePrims) { 
    if (ConstantFoldPrims) { res = tryConstantFold(); }
    if (res == NULL)       { res = tryTypeCheck(); }
    if (res == NULL)       { res = tryInline(); }
  }
  if (res == NULL) {
    // primitive has not been constant-folded nor inlined
    // -> must call primitive at run-time
    res = genCall(_pdesc->can_fail());
  }
  assert(res, "must have result expr");
  _exprStack->pop(_pdesc->number_of_parameters());      // pop parameters
  _exprStack->push2nd(res, _scope, _bci);               // push primitive result
}


Expr* PrimInliner::genCall(bool canFail) {
  // standard primitive call
  //
  // Note: If a primitive fails, it will return a marked symbol. One has to make sure that
  //       this marked symbol is *never* stored on the stack but only kept in registers
  //       (otherwise GC won't work correctly). Here this is established by using the dst()
  //       of a pcall only which is pre-allocated to the result_reg.

  MergeNode*            nlrTestPoint    = _pdesc->can_perform_NLR() ? _scope->nlrTestPoint() : NULL;
  GrowableArray<PReg*>* args            = _gen->pass_arguments(NULL, _pdesc->number_of_parameters());
  GrowableArray<PReg*>* exprStack       = _pdesc->can_walk_stack() ? _gen->copyCurrentExprStack() : NULL;
  PrimNode*             pcall           = NodeFactory::new_PrimNode(_pdesc, nlrTestPoint, args, exprStack);

  _gen->append(pcall);

  BranchNode* branch = NULL;
  if (_failure_block != NULL && canFail) {
    // primitive with failure block; failed if Mark_Tag_Bit is set in result -> add a branch node here
    _gen->append(NodeFactory::new_ArithRCNode(new NoPReg(_scope), pcall->dest(), TestArithOp, Mark_Tag_Bit)); 
    branch = NodeFactory::new_BranchNode(NEBranchOp);
    _gen->append(branch);
  }

  // primitive didn't fail (with or without failure block) -> assign to resPReg & determine its expression
  SAPReg* resPReg = new SAPReg(_scope);
  _gen->append(NodeFactory::new_AssignNode(pcall->dst(), resPReg));
  Node* ok_exit = _gen->_current;
  Expr* resExpr = _pdesc->return_klass(resPReg, ok_exit);
  if (resExpr == NULL) resExpr = new UnknownExpr(resPReg, ok_exit);

  if (branch != NULL) {
    // add failure block if primitive can fail -> reset Mark_Tag_Bit first
    SAPReg* errPReg = new SAPReg(_scope);
    ArithRCNode* failure_exit = NodeFactory::new_ArithRCNode(errPReg, pcall->dst(), AndArithOp, ~Mark_Tag_Bit);
    branch->append(1, failure_exit);
    resExpr = merge_failure_block(ok_exit, resExpr, failure_exit, new KlassExpr(Universe::symbolKlassObj(), errPReg, failure_exit), false);
  }

  return resExpr;
}


void PrimInliner::print() {
  std->print("a PrimInliner\n");
}


# endif

---