view src/share/vm/c1/c1_LIRGenerator.hpp @ 2346:e1162778c1c8

7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error Summary: A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer. Reviewed-by: kvn, iveresov, never, tonyp, dholmes
author johnc
date Thu, 07 Apr 2011 09:53:20 -0700
parents 403dc4c1d7f5
children 701a83c86f28
line wrap: on
line source
/*
 * Copyright (c) 2005, 2011, 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_VM_C1_C1_LIRGENERATOR_HPP
#define SHARE_VM_C1_C1_LIRGENERATOR_HPP

#include "c1/c1_Instruction.hpp"
#include "c1/c1_LIR.hpp"
#include "ci/ciMethodData.hpp"
#include "utilities/sizes.hpp"

// The classes responsible for code emission and register allocation


class LIRGenerator;
class LIREmitter;
class Invoke;
class SwitchRange;
class LIRItem;

define_array(LIRItemArray, LIRItem*)
define_stack(LIRItemList, LIRItemArray)

class SwitchRange: public CompilationResourceObj {
 private:
  int _low_key;
  int _high_key;
  BlockBegin* _sux;
 public:
  SwitchRange(int start_key, BlockBegin* sux): _low_key(start_key), _high_key(start_key), _sux(sux) {}
  void set_high_key(int key) { _high_key = key; }

  int high_key() const { return _high_key; }
  int low_key() const { return _low_key; }
  BlockBegin* sux() const { return _sux; }
};

define_array(SwitchRangeArray, SwitchRange*)
define_stack(SwitchRangeList, SwitchRangeArray)


class ResolveNode;

define_array(NodeArray, ResolveNode*);
define_stack(NodeList, NodeArray);


// Node objects form a directed graph of LIR_Opr
// Edges between Nodes represent moves from one Node to its destinations
class ResolveNode: public CompilationResourceObj {
 private:
  LIR_Opr    _operand;       // the source or destinaton
  NodeList   _destinations;  // for the operand
  bool       _assigned;      // Value assigned to this Node?
  bool       _visited;       // Node already visited?
  bool       _start_node;    // Start node already visited?

 public:
  ResolveNode(LIR_Opr operand)
    : _operand(operand)
    , _assigned(false)
    , _visited(false)
    , _start_node(false) {};

  // accessors
  LIR_Opr operand() const           { return _operand; }
  int no_of_destinations() const    { return _destinations.length(); }
  ResolveNode* destination_at(int i)     { return _destinations[i]; }
  bool assigned() const             { return _assigned; }
  bool visited() const              { return _visited; }
  bool start_node() const           { return _start_node; }

  // modifiers
  void append(ResolveNode* dest)         { _destinations.append(dest); }
  void set_assigned()               { _assigned = true; }
  void set_visited()                { _visited = true; }
  void set_start_node()             { _start_node = true; }
};


// This is shared state to be used by the PhiResolver so the operand
// arrays don't have to be reallocated for reach resolution.
class PhiResolverState: public CompilationResourceObj {
  friend class PhiResolver;

 private:
  NodeList _virtual_operands; // Nodes where the operand is a virtual register
  NodeList _other_operands;   // Nodes where the operand is not a virtual register
  NodeList _vreg_table;       // Mapping from virtual register to Node

 public:
  PhiResolverState() {}

  void reset(int max_vregs);
};


// class used to move value of phi operand to phi function
class PhiResolver: public CompilationResourceObj {
 private:
  LIRGenerator*     _gen;
  PhiResolverState& _state; // temporary state cached by LIRGenerator

  ResolveNode*   _loop;
  LIR_Opr _temp;

  // access to shared state arrays
  NodeList& virtual_operands() { return _state._virtual_operands; }
  NodeList& other_operands()   { return _state._other_operands;   }
  NodeList& vreg_table()       { return _state._vreg_table;       }

  ResolveNode* create_node(LIR_Opr opr, bool source);
  ResolveNode* source_node(LIR_Opr opr)      { return create_node(opr, true); }
  ResolveNode* destination_node(LIR_Opr opr) { return create_node(opr, false); }

  void emit_move(LIR_Opr src, LIR_Opr dest);
  void move_to_temp(LIR_Opr src);
  void move_temp_to(LIR_Opr dest);
  void move(ResolveNode* src, ResolveNode* dest);

  LIRGenerator* gen() {
    return _gen;
  }

 public:
  PhiResolver(LIRGenerator* _lir_gen, int max_vregs);
  ~PhiResolver();

  void move(LIR_Opr src, LIR_Opr dest);
};


// only the classes below belong in the same file
class LIRGenerator: public InstructionVisitor, public BlockClosure {

 private:
  Compilation*  _compilation;
  ciMethod*     _method;    // method that we are compiling
  PhiResolverState  _resolver_state;
  BlockBegin*   _block;
  int           _virtual_register_number;
  Values        _instruction_for_operand;
  BitMap2D      _vreg_flags; // flags which can be set on a per-vreg basis
  LIR_List*     _lir;
  BarrierSet*   _bs;

  LIRGenerator* gen() {
    return this;
  }

#ifdef ASSERT
  LIR_List* lir(const char * file, int line) const {
    _lir->set_file_and_line(file, line);
    return _lir;
  }
#endif
  LIR_List* lir() const {
    return _lir;
  }

  // a simple cache of constants used within a block
  GrowableArray<LIR_Const*>       _constants;
  LIR_OprList                     _reg_for_constants;
  Values                          _unpinned_constants;

  friend class PhiResolver;

  // unified bailout support
  void bailout(const char* msg) const            { compilation()->bailout(msg); }
  bool bailed_out() const                        { return compilation()->bailed_out(); }

  void block_do_prolog(BlockBegin* block);
  void block_do_epilog(BlockBegin* block);

  // register allocation
  LIR_Opr rlock(Value instr);                      // lock a free register
  LIR_Opr rlock_result(Value instr);
  LIR_Opr rlock_result(Value instr, BasicType type);
  LIR_Opr rlock_byte(BasicType type);
  LIR_Opr rlock_callee_saved(BasicType type);

  // get a constant into a register and get track of what register was used
  LIR_Opr load_constant(Constant* x);
  LIR_Opr load_constant(LIR_Const* constant);

  // Given an immediate value, return an operand usable in logical ops.
  LIR_Opr load_immediate(int x, BasicType type);

  void  set_result(Value x, LIR_Opr opr)           {
    assert(opr->is_valid(), "must set to valid value");
    assert(x->operand()->is_illegal(), "operand should never change");
    assert(!opr->is_register() || opr->is_virtual(), "should never set result to a physical register");
    x->set_operand(opr);
    assert(opr == x->operand(), "must be");
    if (opr->is_virtual()) {
      _instruction_for_operand.at_put_grow(opr->vreg_number(), x, NULL);
    }
  }
  void  set_no_result(Value x)                     { assert(!x->has_uses(), "can't have use"); x->clear_operand(); }

  friend class LIRItem;

  LIR_Opr round_item(LIR_Opr opr);
  LIR_Opr force_to_spill(LIR_Opr value, BasicType t);

  PhiResolverState& resolver_state() { return _resolver_state; }

  void  move_to_phi(PhiResolver* resolver, Value cur_val, Value sux_val);
  void  move_to_phi(ValueStack* cur_state);

  // code emission
  void do_ArithmeticOp_Long   (ArithmeticOp*    x);
  void do_ArithmeticOp_Int    (ArithmeticOp*    x);
  void do_ArithmeticOp_FPU    (ArithmeticOp*    x);

  // platform dependent
  LIR_Opr getThreadPointer();

  void do_RegisterFinalizer(Intrinsic* x);
  void do_getClass(Intrinsic* x);
  void do_currentThread(Intrinsic* x);
  void do_MathIntrinsic(Intrinsic* x);
  void do_ArrayCopy(Intrinsic* x);
  void do_CompareAndSwap(Intrinsic* x, ValueType* type);
  void do_AttemptUpdate(Intrinsic* x);
  void do_NIOCheckIndex(Intrinsic* x);
  void do_FPIntrinsics(Intrinsic* x);
  void do_Reference_get(Intrinsic* x);

  void do_UnsafePrefetch(UnsafePrefetch* x, bool is_store);

  LIR_Opr call_runtime(BasicTypeArray* signature, LIRItemList* args, address entry, ValueType* result_type, CodeEmitInfo* info);
  LIR_Opr call_runtime(BasicTypeArray* signature, LIR_OprList* args, address entry, ValueType* result_type, CodeEmitInfo* info);

  // convenience functions
  LIR_Opr call_runtime(Value arg1, address entry, ValueType* result_type, CodeEmitInfo* info);
  LIR_Opr call_runtime(Value arg1, Value arg2, address entry, ValueType* result_type, CodeEmitInfo* info);

  // GC Barriers

  // generic interface

  void pre_barrier(LIR_Opr addr_opr, LIR_Opr pre_val, bool do_load, bool patch, CodeEmitInfo* info);
  void post_barrier(LIR_OprDesc* addr, LIR_OprDesc* new_val);

  // specific implementations
  // pre barriers

  void G1SATBCardTableModRef_pre_barrier(LIR_Opr addr_opr, LIR_Opr pre_val,
                                         bool do_load, bool patch, CodeEmitInfo* info);

  // post barriers

  void G1SATBCardTableModRef_post_barrier(LIR_OprDesc* addr, LIR_OprDesc* new_val);
  void CardTableModRef_post_barrier(LIR_OprDesc* addr, LIR_OprDesc* new_val);


  static LIR_Opr result_register_for(ValueType* type, bool callee = false);

  ciObject* get_jobject_constant(Value value);

  LIRItemList* invoke_visit_arguments(Invoke* x);
  void invoke_load_arguments(Invoke* x, LIRItemList* args, const LIR_OprList* arg_list);

  void trace_block_entry(BlockBegin* block);

  // volatile field operations are never patchable because a klass
  // must be loaded to know it's volatile which means that the offset
  // it always known as well.
  void volatile_field_store(LIR_Opr value, LIR_Address* address, CodeEmitInfo* info);
  void volatile_field_load(LIR_Address* address, LIR_Opr result, CodeEmitInfo* info);

  void put_Object_unsafe(LIR_Opr src, LIR_Opr offset, LIR_Opr data, BasicType type, bool is_volatile);
  void get_Object_unsafe(LIR_Opr dest, LIR_Opr src, LIR_Opr offset, BasicType type, bool is_volatile);

  void arithmetic_call_op (Bytecodes::Code code, LIR_Opr result, LIR_OprList* args);

  void increment_counter(address counter, BasicType type, int step = 1);
  void increment_counter(LIR_Address* addr, int step = 1);

  // is_strictfp is only needed for mul and div (and only generates different code on i486)
  void arithmetic_op(Bytecodes::Code code, LIR_Opr result, LIR_Opr left, LIR_Opr right, bool is_strictfp, LIR_Opr tmp, CodeEmitInfo* info = NULL);
  // machine dependent.  returns true if it emitted code for the multiply
  bool strength_reduce_multiply(LIR_Opr left, int constant, LIR_Opr result, LIR_Opr tmp);

  void store_stack_parameter (LIR_Opr opr, ByteSize offset_from_sp_in_bytes);

  void jobject2reg_with_patching(LIR_Opr r, ciObject* obj, CodeEmitInfo* info);

  // this loads the length and compares against the index
  void array_range_check          (LIR_Opr array, LIR_Opr index, CodeEmitInfo* null_check_info, CodeEmitInfo* range_check_info);
  // For java.nio.Buffer.checkIndex
  void nio_range_check            (LIR_Opr buffer, LIR_Opr index, LIR_Opr result, CodeEmitInfo* info);

  void arithmetic_op_int  (Bytecodes::Code code, LIR_Opr result, LIR_Opr left, LIR_Opr right, LIR_Opr tmp);
  void arithmetic_op_long (Bytecodes::Code code, LIR_Opr result, LIR_Opr left, LIR_Opr right, CodeEmitInfo* info = NULL);
  void arithmetic_op_fpu  (Bytecodes::Code code, LIR_Opr result, LIR_Opr left, LIR_Opr right, bool is_strictfp, LIR_Opr tmp = LIR_OprFact::illegalOpr);

  void shift_op   (Bytecodes::Code code, LIR_Opr dst_reg, LIR_Opr value, LIR_Opr count, LIR_Opr tmp);

  void logic_op   (Bytecodes::Code code, LIR_Opr dst_reg, LIR_Opr left, LIR_Opr right);

  void monitor_enter (LIR_Opr object, LIR_Opr lock, LIR_Opr hdr, LIR_Opr scratch, int monitor_no, CodeEmitInfo* info_for_exception, CodeEmitInfo* info);
  void monitor_exit  (LIR_Opr object, LIR_Opr lock, LIR_Opr hdr, LIR_Opr scratch, int monitor_no);

  void new_instance    (LIR_Opr  dst, ciInstanceKlass* klass, LIR_Opr  scratch1, LIR_Opr  scratch2, LIR_Opr  scratch3,  LIR_Opr scratch4, LIR_Opr  klass_reg, CodeEmitInfo* info);

  // machine dependent
  void cmp_mem_int(LIR_Condition condition, LIR_Opr base, int disp, int c, CodeEmitInfo* info);
  void cmp_reg_mem(LIR_Condition condition, LIR_Opr reg, LIR_Opr base, int disp, BasicType type, CodeEmitInfo* info);
  void cmp_reg_mem(LIR_Condition condition, LIR_Opr reg, LIR_Opr base, LIR_Opr disp, BasicType type, CodeEmitInfo* info);

  void arraycopy_helper(Intrinsic* x, int* flags, ciArrayKlass** expected_type);

  // returns a LIR_Address to address an array location.  May also
  // emit some code as part of address calculation.  If
  // needs_card_mark is true then compute the full address for use by
  // both the store and the card mark.
  LIR_Address* generate_address(LIR_Opr base,
                                LIR_Opr index, int shift,
                                int disp,
                                BasicType type);
  LIR_Address* generate_address(LIR_Opr base, int disp, BasicType type) {
    return generate_address(base, LIR_OprFact::illegalOpr, 0, disp, type);
  }
  LIR_Address* emit_array_address(LIR_Opr array_opr, LIR_Opr index_opr, BasicType type, bool needs_card_mark);

  // the helper for generate_address
  void add_large_constant(LIR_Opr src, int c, LIR_Opr dest);

  // machine preferences and characteristics
  bool can_inline_as_constant(Value i) const;
  bool can_inline_as_constant(LIR_Const* c) const;
  bool can_store_as_constant(Value i, BasicType type) const;

  LIR_Opr safepoint_poll_register();

  void profile_branch(If* if_instr, If::Condition cond);
  void increment_event_counter_impl(CodeEmitInfo* info,
                                    ciMethod *method, int frequency,
                                    int bci, bool backedge, bool notify);
  void increment_event_counter(CodeEmitInfo* info, int bci, bool backedge);
  void increment_invocation_counter(CodeEmitInfo *info) {
    if (compilation()->count_invocations()) {
      increment_event_counter(info, InvocationEntryBci, false);
    }
  }
  void increment_backedge_counter(CodeEmitInfo* info, int bci) {
    if (compilation()->count_backedges()) {
      increment_event_counter(info, bci, true);
    }
  }

  CodeEmitInfo* state_for(Instruction* x, ValueStack* state, bool ignore_xhandler = false);
  CodeEmitInfo* state_for(Instruction* x);

  // allocates a virtual register for this instruction if
  // one isn't already allocated.  Only for Phi and Local.
  LIR_Opr operand_for_instruction(Instruction *x);

  void set_block(BlockBegin* block)              { _block = block; }

  void block_prolog(BlockBegin* block);
  void block_epilog(BlockBegin* block);

  void do_root (Instruction* instr);
  void walk    (Instruction* instr);

  void bind_block_entry(BlockBegin* block);
  void start_block(BlockBegin* block);

  LIR_Opr new_register(BasicType type);
  LIR_Opr new_register(Value value)              { return new_register(as_BasicType(value->type())); }
  LIR_Opr new_register(ValueType* type)          { return new_register(as_BasicType(type)); }

  // returns a register suitable for doing pointer math
  LIR_Opr new_pointer_register() {
#ifdef _LP64
    return new_register(T_LONG);
#else
    return new_register(T_INT);
#endif
  }

  static LIR_Condition lir_cond(If::Condition cond) {
    LIR_Condition l;
    switch (cond) {
    case If::eql: l = lir_cond_equal;        break;
    case If::neq: l = lir_cond_notEqual;     break;
    case If::lss: l = lir_cond_less;         break;
    case If::leq: l = lir_cond_lessEqual;    break;
    case If::geq: l = lir_cond_greaterEqual; break;
    case If::gtr: l = lir_cond_greater;      break;
    };
    return l;
  }

#ifdef __SOFTFP__
  void do_soft_float_compare(If *x);
#endif // __SOFTFP__

  void init();

  SwitchRangeArray* create_lookup_ranges(TableSwitch* x);
  SwitchRangeArray* create_lookup_ranges(LookupSwitch* x);
  void do_SwitchRanges(SwitchRangeArray* x, LIR_Opr value, BlockBegin* default_sux);

 public:
  Compilation*  compilation() const              { return _compilation; }
  FrameMap*     frame_map() const                { return _compilation->frame_map(); }
  ciMethod*     method() const                   { return _method; }
  BlockBegin*   block() const                    { return _block; }
  IRScope*      scope() const                    { return block()->scope(); }

  int max_virtual_register_number() const        { return _virtual_register_number; }

  void block_do(BlockBegin* block);

  // Flags that can be set on vregs
  enum VregFlag {
      must_start_in_memory = 0  // needs to be assigned a memory location at beginning, but may then be loaded in a register
    , callee_saved     = 1    // must be in a callee saved register
    , byte_reg         = 2    // must be in a byte register
    , num_vreg_flags

  };

  LIRGenerator(Compilation* compilation, ciMethod* method)
    : _compilation(compilation)
    , _method(method)
    , _virtual_register_number(LIR_OprDesc::vreg_base)
    , _vreg_flags(NULL, 0, num_vreg_flags) {
    init();
  }

  // for virtual registers, maps them back to Phi's or Local's
  Instruction* instruction_for_opr(LIR_Opr opr);
  Instruction* instruction_for_vreg(int reg_num);

  void set_vreg_flag   (int vreg_num, VregFlag f);
  bool is_vreg_flag_set(int vreg_num, VregFlag f);
  void set_vreg_flag   (LIR_Opr opr,  VregFlag f) { set_vreg_flag(opr->vreg_number(), f); }
  bool is_vreg_flag_set(LIR_Opr opr,  VregFlag f) { return is_vreg_flag_set(opr->vreg_number(), f); }

  // statics
  static LIR_Opr exceptionOopOpr();
  static LIR_Opr exceptionPcOpr();
  static LIR_Opr divInOpr();
  static LIR_Opr divOutOpr();
  static LIR_Opr remOutOpr();
  static LIR_Opr shiftCountOpr();
  LIR_Opr syncTempOpr();
  LIR_Opr atomicLockOpr();

  // returns a register suitable for saving the thread in a
  // call_runtime_leaf if one is needed.
  LIR_Opr getThreadTemp();

  // visitor functionality
  virtual void do_Phi            (Phi*             x);
  virtual void do_Local          (Local*           x);
  virtual void do_Constant       (Constant*        x);
  virtual void do_LoadField      (LoadField*       x);
  virtual void do_StoreField     (StoreField*      x);
  virtual void do_ArrayLength    (ArrayLength*     x);
  virtual void do_LoadIndexed    (LoadIndexed*     x);
  virtual void do_StoreIndexed   (StoreIndexed*    x);
  virtual void do_NegateOp       (NegateOp*        x);
  virtual void do_ArithmeticOp   (ArithmeticOp*    x);
  virtual void do_ShiftOp        (ShiftOp*         x);
  virtual void do_LogicOp        (LogicOp*         x);
  virtual void do_CompareOp      (CompareOp*       x);
  virtual void do_IfOp           (IfOp*            x);
  virtual void do_Convert        (Convert*         x);
  virtual void do_NullCheck      (NullCheck*       x);
  virtual void do_Invoke         (Invoke*          x);
  virtual void do_NewInstance    (NewInstance*     x);
  virtual void do_NewTypeArray   (NewTypeArray*    x);
  virtual void do_NewObjectArray (NewObjectArray*  x);
  virtual void do_NewMultiArray  (NewMultiArray*   x);
  virtual void do_CheckCast      (CheckCast*       x);
  virtual void do_InstanceOf     (InstanceOf*      x);
  virtual void do_MonitorEnter   (MonitorEnter*    x);
  virtual void do_MonitorExit    (MonitorExit*     x);
  virtual void do_Intrinsic      (Intrinsic*       x);
  virtual void do_BlockBegin     (BlockBegin*      x);
  virtual void do_Goto           (Goto*            x);
  virtual void do_If             (If*              x);
  virtual void do_IfInstanceOf   (IfInstanceOf*    x);
  virtual void do_TableSwitch    (TableSwitch*     x);
  virtual void do_LookupSwitch   (LookupSwitch*    x);
  virtual void do_Return         (Return*          x);
  virtual void do_Throw          (Throw*           x);
  virtual void do_Base           (Base*            x);
  virtual void do_OsrEntry       (OsrEntry*        x);
  virtual void do_ExceptionObject(ExceptionObject* x);
  virtual void do_RoundFP        (RoundFP*         x);
  virtual void do_UnsafeGetRaw   (UnsafeGetRaw*    x);
  virtual void do_UnsafePutRaw   (UnsafePutRaw*    x);
  virtual void do_UnsafeGetObject(UnsafeGetObject* x);
  virtual void do_UnsafePutObject(UnsafePutObject* x);
  virtual void do_UnsafePrefetchRead (UnsafePrefetchRead*  x);
  virtual void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x);
  virtual void do_ProfileCall    (ProfileCall*     x);
  virtual void do_ProfileInvoke  (ProfileInvoke*   x);
  virtual void do_RuntimeCall    (RuntimeCall*     x);
};


class LIRItem: public CompilationResourceObj {
 private:
  Value         _value;
  LIRGenerator* _gen;
  LIR_Opr       _result;
  bool          _destroys_register;
  LIR_Opr       _new_result;

  LIRGenerator* gen() const { return _gen; }

 public:
  LIRItem(Value value, LIRGenerator* gen) {
    _destroys_register = false;
    _gen = gen;
    set_instruction(value);
  }

  LIRItem(LIRGenerator* gen) {
    _destroys_register = false;
    _gen = gen;
    _result = LIR_OprFact::illegalOpr;
    set_instruction(NULL);
  }

  void set_instruction(Value value) {
    _value = value;
    _result = LIR_OprFact::illegalOpr;
    if (_value != NULL) {
      _gen->walk(_value);
      _result = _value->operand();
    }
    _new_result = LIR_OprFact::illegalOpr;
  }

  Value value() const          { return _value;          }
  ValueType* type() const      { return value()->type(); }
  LIR_Opr result()             {
    assert(!_destroys_register || (!_result->is_register() || _result->is_virtual()),
           "shouldn't use set_destroys_register with physical regsiters");
    if (_destroys_register && _result->is_register()) {
      if (_new_result->is_illegal()) {
        _new_result = _gen->new_register(type());
        gen()->lir()->move(_result, _new_result);
      }
      return _new_result;
    } else {
      return _result;
    }
    return _result;
  }

  void set_result(LIR_Opr opr);

  void load_item();
  void load_byte_item();
  void load_nonconstant();
  // load any values which can't be expressed as part of a single store instruction
  void load_for_store(BasicType store_type);
  void load_item_force(LIR_Opr reg);

  void dont_load_item() {
    // do nothing
  }

  void set_destroys_register() {
    _destroys_register = true;
  }

  bool is_constant() const { return value()->as_Constant() != NULL; }
  bool is_stack()          { return result()->is_stack(); }
  bool is_register()       { return result()->is_register(); }

  ciObject* get_jobject_constant() const;
  jint      get_jint_constant() const;
  jlong     get_jlong_constant() const;
  jfloat    get_jfloat_constant() const;
  jdouble   get_jdouble_constant() const;
  jint      get_address_constant() const;
};

#endif // SHARE_VM_C1_C1_LIRGENERATOR_HPP