1 /*

     2  * Copyright 2006-2007 Sun Microsystems, Inc.  All Rights Reserved.

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

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 //------------------------------OptoReg----------------------------------------

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

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

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

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

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

    31 // register.

    32 //

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

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

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

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

    37 // conventions and is described in the ADL.

    38 //

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

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

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

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

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

    44 //

    45 class OptoReg VALUE_OBJ_CLASS_SPEC {

    46 

    47  friend class C2Compiler;

    48  public:

    49   typedef int Name;

    50   enum {

    51     // Chunk 0

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

    53     // A few oddballs at the edge of the world

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

    55     Bad = -1                    // Not a register

    56   };

    57 

    58  private:

    59 

    60  static const VMReg opto2vm[REG_COUNT];

    61  static Name vm2opto[ConcreteRegisterImpl::number_of_registers];

    62 

    63  public:

    64 

    65   // Stack pointer register

    66   static OptoReg::Name c_frame_pointer;

    67 

    68 

    69 

    70   // Increment a register number.  As in:

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

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

    73 

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

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

    76 

    77   static void dump( int );

    78 

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

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

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

    82     return r - stack0();

    83   }

    84 

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

    86   static OptoReg::Name stack2reg( int idx) {

    87     return Name(stack0() + idx);

    88   }

    89 

    90   static bool is_stack(Name n) {

    91     return n >= stack0();

    92   }

    93 

    94   static bool is_valid(Name n) {

    95     return (n != Bad);

    96   }

    97 

    98   static bool is_reg(Name n) {

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

   100   }

   101 

   102   static VMReg as_VMReg(OptoReg::Name n) {

   103     if (is_reg(n)) {

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

   105       return opto2vm[n];

   106     } else {

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

   108       return VMRegImpl::Bad();

   109     }

   110   }

   111 

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

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

   114     if (is_reg(n)) {

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

   116       return opto2vm[n];

   117     } else if (is_stack(n)) {

   118       int stack_slot = reg2stack(n);

   119       if (stack_slot < arg_count) {

   120         return VMRegImpl::stack2reg(stack_slot + frame_size);

   121       }

   122       return VMRegImpl::stack2reg(stack_slot - arg_count);

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

   124     } else {

   125       return VMRegImpl::Bad();

   126     }

   127   }

   128 

   129   static OptoReg::Name as_OptoReg(VMReg r) {

   130     if (r->is_stack()) {

   131       assert(false, "must warp");

   132       return stack2reg(r->reg2stack());

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

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

   135       return vm2opto[r->value()];

   136     } else {

   137       return Bad;

   138     }

   139   }

   140 

   141   static OptoReg::Name stack0() {

   142     return VMRegImpl::stack0->value();

   143   }

   144 

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

   146     return as_VMReg(n)->name();

   147   }

   148 

   149 };

   150 

   151 //---------------------------OptoRegPair-------------------------------------------

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

   170 

   171 class OptoRegPair {

   172 private:

   173   short _second;

   174   short _first;

   175 public:

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

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

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

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

   180   void set_ptr ( OptoReg::Name ptr ) {

   181 #ifdef _LP64

   182     _second = ptr+1;

   183 #else

   184     _second = OptoReg::Bad;

   185 #endif

   186     _first = ptr;

   187   }

   188 

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

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

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

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

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

   194 };