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 /*

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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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  * published by the Free Software Foundation.

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  * 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.

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 #ifndef SHARE_VM_OPTO_OPTOREG_HPP

 #define SHARE_VM_OPTO_OPTOREG_HPP

 //------------------------------OptoReg----------------------------------------

 // We eventually need Registers for the Real World.  Registers are essentially

 // non-SSA names.  A Register is represented as a number.  Non-regular values

 // (e.g., Control, Memory, I/O) use the Special register.  The actual machine

 // registers (as described in the ADL file for a machine) start at zero.

 // Stack-slots (spill locations) start at the nest Chunk past the last machine

 // register.

 //

 // Note that stack spill-slots are treated as a very large register set.

 // They have all the correct properties for a Register: not aliased (unique

 // named).  There is some simple mapping from a stack-slot register number

 // to the actual location on the stack; this mapping depends on the calling

 // conventions and is described in the ADL.

 //

 // Note that Name is not enum. C++ standard defines that the range of enum

 // is the range of smallest bit-field that can represent all enumerators

 // declared in the enum. The result of assigning a value to enum is undefined

 // if the value is outside the enumeration's valid range. OptoReg::Name is

 // typedef'ed as int, because it needs to be able to represent spill-slots.

 //

 class OptoReg VALUE_OBJ_CLASS_SPEC {

  friend class C2Compiler;

  public:

   typedef int Name;

   enum {

     // Chunk 0

     Physical = AdlcVMDeps::Physical, // Start of physical regs

     // A few oddballs at the edge of the world

     Special = -2,               // All special (not allocated) values

     Bad = -1                    // Not a register

   };

  private:

  static const VMReg opto2vm[REG_COUNT];

  static Name vm2opto[ConcreteRegisterImpl::number_of_registers];

  public:

   // Stack pointer register

   static OptoReg::Name c_frame_pointer;

   // Increment a register number.  As in:

   //    "for ( OptoReg::Name i; i=Control; i = add(i,1) ) ..."

   static Name add( Name x, int y ) { return Name(x+y); }

   // (We would like to have an operator+ for RegName, but it is not

   // a class, so this would be illegal in C++.)

   static void dump(int, outputStream *st = tty);

   // Get the stack slot number of an OptoReg::Name

   static unsigned int reg2stack( OptoReg::Name r) {

     assert( r >= stack0(), " must be");

     return r - stack0();

   }

   // convert a stack slot number into an OptoReg::Name

   static OptoReg::Name stack2reg( int idx) {

     return Name(stack0() + idx);

   }

   static bool is_stack(Name n) {

     return n >= stack0();

   }

   static bool is_valid(Name n) {

     return (n != Bad);

   }

   static bool is_reg(Name n) {

     return  is_valid(n) && !is_stack(n);

   }

   static VMReg as_VMReg(OptoReg::Name n) {

     if (is_reg(n)) {

       // Must use table, it'd be nice if Bad was indexable...

       return opto2vm[n];

     } else {

       assert(!is_stack(n), "must un warp");

       return VMRegImpl::Bad();

     }

   }

   // Can un-warp a stack slot or convert a register or Bad

   static VMReg as_VMReg(OptoReg::Name n, int frame_size, int arg_count) {

     if (is_reg(n)) {

       // Must use table, it'd be nice if Bad was indexable...

       return opto2vm[n];

     } else if (is_stack(n)) {

       int stack_slot = reg2stack(n);

       if (stack_slot < arg_count) {

         return VMRegImpl::stack2reg(stack_slot + frame_size);

       }

       return VMRegImpl::stack2reg(stack_slot - arg_count);

       // return return VMRegImpl::stack2reg(reg2stack(OptoReg::add(n, -arg_count)));

     } else {

       return VMRegImpl::Bad();

     }

   }

   static OptoReg::Name as_OptoReg(VMReg r) {

     if (r->is_stack()) {

       assert(false, "must warp");

       return stack2reg(r->reg2stack());

     } else if (r->is_valid()) {

       // Must use table, it'd be nice if Bad was indexable...

       return vm2opto[r->value()];

     } else {

       return Bad;

     }

   }

   static OptoReg::Name stack0() {

     return VMRegImpl::stack0->value();

   }

   static const char* regname(OptoReg::Name n) {

     return as_VMReg(n)->name();

   }

 };

 //---------------------------OptoRegPair-------------------------------------------

 // Pairs of 32-bit registers for the allocator.

 // This is a very similar class to VMRegPair. C2 only interfaces with VMRegPair

 // via the calling convention code which is shared between the compilers.

 // Since C2 uses OptoRegs for register allocation it is more efficient to use

 // VMRegPair internally for nodes that can contain a pair of OptoRegs rather

 // than use VMRegPair and continually be converting back and forth. So normally

 // C2 will take in a VMRegPair from the calling convention code and immediately

 // convert them to an OptoRegPair and stay in the OptoReg world. The only over

 // conversion between OptoRegs and VMRegs is for debug info and oopMaps. This

 // is not a high bandwidth spot and so it is not an issue.

 // Note that onde other consequence of staying in the OptoReg world with OptoRegPairs

 // is that there are "physical" OptoRegs that are not representable in the VMReg

 // world, notably flags. [ But by design there is "space" in the VMReg world

 // for such registers they just may not be concrete ]. So if we were to use VMRegPair

 // then the VMReg world would have to have a representation for these registers

 // so that a OptoReg->VMReg->OptoReg would reproduce ther original OptoReg. As it

 // stands if you convert a flag (condition code) to a VMReg you will get VMRegImpl::Bad

 // and converting that will return OptoReg::Bad losing the identity of the OptoReg.

 class OptoRegPair {

   friend class VMStructs;

 private:

   short _second;

   short _first;

 public:

   void set_bad (                   ) { _second = OptoReg::Bad; _first = OptoReg::Bad; }

   void set1    ( OptoReg::Name n  ) { _second = OptoReg::Bad; _first = n; }

   void set2    ( OptoReg::Name n  ) { _second = n + 1;       _first = n; }

   void set_pair( OptoReg::Name second, OptoReg::Name first    ) { _second= second;    _first= first; }

   void set_ptr ( OptoReg::Name ptr ) {

 #ifdef _LP64

     _second = ptr+1;

 #else

     _second = OptoReg::Bad;

 #endif

     _first = ptr;

   }

   OptoReg::Name second() const { return _second; }

   OptoReg::Name first() const { return _first; }

   OptoRegPair(OptoReg::Name second, OptoReg::Name first) {  _second = second; _first = first; }

   OptoRegPair(OptoReg::Name f) { _second = OptoReg::Bad; _first = f; }

   OptoRegPair() { _second = OptoReg::Bad; _first = OptoReg::Bad; }

 };

 #endif // SHARE_VM_OPTO_OPTOREG_HPP