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 /*

  * Copyright (c) 1998, 2008, 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

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  */

 //------------------------------VMReg------------------------------------------

 // The VM uses 'unwarped' stack slots; the compiler uses 'warped' stack slots.

 // Register numbers below VMRegImpl::stack0 are the same for both.  Register

 // numbers above stack0 are either warped (in the compiler) or unwarped

 // (in the VM).  Unwarped numbers represent stack indices, offsets from

 // the current stack pointer.  Warped numbers are required during compilation

 // when we do not yet know how big the frame will be.

 class VMRegImpl;

 typedef VMRegImpl* VMReg;

 class VMRegImpl {

 // friend class OopMap;

 friend class VMStructs;

 friend class OptoReg;

 // friend class Location;

 private:

   enum {

     BAD = -1

   };

   static VMReg stack0;

   // Names for registers

   static const char *regName[];

   static const int register_count;

 public:

   static VMReg  as_VMReg(int val, bool bad_ok = false) { assert(val > BAD || bad_ok, "invalid"); return (VMReg) (intptr_t) val; }

   const char*  name() {

     if (is_reg()) {

       return regName[value()];

     } else if (!is_valid()) {

       return "BAD";

     } else {

       // shouldn't really be called with stack

       return "STACKED REG";

     }

   }

   static VMReg Bad() { return (VMReg) (intptr_t) BAD; }

   bool is_valid() const { return ((intptr_t) this) != BAD; }

   bool is_stack() const { return (intptr_t) this >= (intptr_t) stack0; }

   bool is_reg()   const { return is_valid() && !is_stack(); }

   // A concrete register is a value that returns true for is_reg() and is

   // also a register you could use in the assembler. On machines with

   // 64bit registers only one half of the VMReg (and OptoReg) is considered

   // concrete.

   bool is_concrete();

   // VMRegs are 4 bytes wide on all platforms

   static const int stack_slot_size;

   static const int slots_per_word;

   // This really ought to check that the register is "real" in the sense that

   // we don't try and get the VMReg number of a physical register that doesn't

   // have an expressible part. That would be pd specific code

   VMReg next() {

     assert((is_reg() && value() < stack0->value() - 1) || is_stack(), "must be");

     return (VMReg)(intptr_t)(value() + 1);

   }

   VMReg prev() {

     assert((is_stack() && value() > stack0->value()) || (is_reg() && value() != 0), "must be");

     return (VMReg)(intptr_t)(value() - 1);

   }

   intptr_t value() const         {return (intptr_t) this; }

   void print_on(outputStream* st) const;

   void print() const { print_on(tty); }

   // bias a stack slot.

   // Typically used to adjust a virtual frame slots by amounts that are offset by

   // amounts that are part of the native abi. The VMReg must be a stack slot

   // and the result must be also.

   VMReg bias(int offset) {

     assert(is_stack(), "must be");

     // VMReg res = VMRegImpl::as_VMReg(value() + offset);

     VMReg res = stack2reg(reg2stack() + offset);

     assert(res->is_stack(), "must be");

     return res;

   }

   // Convert register numbers to stack slots and vice versa

   static VMReg stack2reg( int idx ) {

     return (VMReg) (intptr_t) (stack0->value() + idx);

   }

   uintptr_t reg2stack() {

     assert( is_stack(), "Not a stack-based register" );

     return value() - stack0->value();

   }

   static void set_regName();

 #include "incls/_vmreg_pd.hpp.incl"

 };

 //---------------------------VMRegPair-------------------------------------------

 // Pairs of 32-bit registers for arguments.

 // SharedRuntime::java_calling_convention will overwrite the structs with

 // the calling convention's registers.  VMRegImpl::Bad is returned for any

 // unused 32-bit register.  This happens for the unused high half of Int

 // arguments, or for 32-bit pointers or for longs in the 32-bit sparc build

 // (which are passed to natives in low 32-bits of e.g. O0/O1 and the high

 // 32-bits of O0/O1 are set to VMRegImpl::Bad).  Longs in one register & doubles

 // always return a high and a low register, as do 64-bit pointers.

 //

 class VMRegPair {

 private:

   VMReg _second;

   VMReg _first;

 public:

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

   void set1    (         VMReg v  ) { _second=VMRegImpl::Bad(); _first=v; }

   void set2    (         VMReg v  ) { _second=v->next();  _first=v; }

   void set_pair( VMReg second, VMReg first    ) { _second= second;    _first= first; }

   void set_ptr ( VMReg ptr ) {

 #ifdef _LP64

     _second = ptr->next();

 #else

     _second = VMRegImpl::Bad();

 #endif

     _first = ptr;

   }

   // Return true if single register, even if the pair is really just adjacent stack slots

   bool is_single_reg() const {

     return (_first->is_valid()) && (_first->value() + 1 == _second->value());

   }

   // Return true if single stack based "register" where the slot alignment matches input alignment

   bool is_adjacent_on_stack(int alignment) const {

     return (_first->is_stack() && (_first->value() + 1 == _second->value()) && ((_first->value() & (alignment-1)) == 0));

   }

   // Return true if single stack based "register" where the slot alignment matches input alignment

   bool is_adjacent_aligned_on_stack(int alignment) const {

     return (_first->is_stack() && (_first->value() + 1 == _second->value()) && ((_first->value() & (alignment-1)) == 0));

   }

   // Return true if single register but adjacent stack slots do not count

   bool is_single_phys_reg() const {

     return (_first->is_reg() && (_first->value() + 1 == _second->value()));

   }

   VMReg second() const { return _second; }

   VMReg first()  const { return _first; }

   VMRegPair(VMReg s, VMReg f) {  _second = s; _first = f; }

   VMRegPair(VMReg f) { _second = VMRegImpl::Bad(); _first = f; }

   VMRegPair() { _second = VMRegImpl::Bad(); _first = VMRegImpl::Bad(); }

 };