1 /*

     2  * Copyright 1997-2006 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 // Portions of code courtesy of Clifford Click

    26 

    27 // Optimization - Graph Style

    28 

    29 class Matcher;

    30 class Node;

    31 class   RegionNode;

    32 class   TypeNode;

    33 class     PhiNode;

    34 class   GotoNode;

    35 class   MultiNode;

    36 class     MultiBranchNode;

    37 class       IfNode;

    38 class       PCTableNode;

    39 class         JumpNode;

    40 class         CatchNode;

    41 class       NeverBranchNode;

    42 class   ProjNode;

    43 class     CProjNode;

    44 class       IfTrueNode;

    45 class       IfFalseNode;

    46 class       CatchProjNode;

    47 class     JProjNode;

    48 class       JumpProjNode;

    49 class     SCMemProjNode;

    50 class PhaseIdealLoop;

    51 

    52 //------------------------------RegionNode-------------------------------------

    53 // The class of RegionNodes, which can be mapped to basic blocks in the

    54 // program.  Their inputs point to Control sources.  PhiNodes (described

    55 // below) have an input point to a RegionNode.  Merged data inputs to PhiNodes

    56 // correspond 1-to-1 with RegionNode inputs.  The zero input of a PhiNode is

    57 // the RegionNode, and the zero input of the RegionNode is itself.

    58 class RegionNode : public Node {

    59 public:

    60   // Node layout (parallels PhiNode):

    61   enum { Region,                // Generally points to self.

    62          Control                // Control arcs are [1..len)

    63   };

    64 

    65   RegionNode( uint required ) : Node(required) {

    66     init_class_id(Class_Region);

    67     init_req(0,this);

    68   }

    69 

    70   Node* is_copy() const {

    71     const Node* r = _in[Region];

    72     if (r == NULL)

    73       return nonnull_req();

    74     return NULL;  // not a copy!

    75   }

    76   PhiNode* has_phi() const;        // returns an arbitrary phi user, or NULL

    77   PhiNode* has_unique_phi() const; // returns the unique phi user, or NULL

    78   // Is this region node unreachable from root?

    79   bool is_unreachable_region(PhaseGVN *phase) const;

    80   virtual int Opcode() const;

    81   virtual bool pinned() const { return (const Node *)in(0) == this; }

    82   virtual bool  is_CFG   () const { return true; }

    83   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash

    84   virtual bool depends_only_on_test() const { return false; }

    85   virtual const Type *bottom_type() const { return Type::CONTROL; }

    86   virtual const Type *Value( PhaseTransform *phase ) const;

    87   virtual Node *Identity( PhaseTransform *phase );

    88   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);

    89   virtual const RegMask &out_RegMask() const;

    90 };

    91 

    92 //------------------------------JProjNode--------------------------------------

    93 // jump projection for node that produces multiple control-flow paths

    94 class JProjNode : public ProjNode {

    95  public:

    96   JProjNode( Node* ctrl, uint idx ) : ProjNode(ctrl,idx) {}

    97   virtual int Opcode() const;

    98   virtual bool  is_CFG() const { return true; }

    99   virtual uint  hash() const { return NO_HASH; }  // CFG nodes do not hash

   100   virtual const Node* is_block_proj() const { return in(0); }

   101   virtual const RegMask& out_RegMask() const;

   102   virtual uint  ideal_reg() const { return 0; }

   103 };

   104 

   105 //------------------------------PhiNode----------------------------------------

   106 // PhiNodes merge values from different Control paths.  Slot 0 points to the

   107 // controlling RegionNode.  Other slots map 1-for-1 with incoming control flow

   108 // paths to the RegionNode.  For speed reasons (to avoid another pass) we

   109 // can turn PhiNodes into copys in-place by NULL'ing out their RegionNode

   110 // input in slot 0.

   111 class PhiNode : public TypeNode {

   112   const TypePtr* const _adr_type; // non-null only for Type::MEMORY nodes.

   113   // Size is bigger to hold the _adr_type field.

   114   virtual uint hash() const;    // Check the type

   115   virtual uint cmp( const Node &n ) const;

   116   virtual uint size_of() const { return sizeof(*this); }

   117 

   118   // Determine a unique non-trivial input, if any.

   119   // Ignore casts if it helps.  Return NULL on failure.

   120   Node* unique_input(PhaseTransform *phase);

   121   // Determine if CMoveNode::is_cmove_id can be used at this join point.

   122   Node* is_cmove_id(PhaseTransform* phase, int true_path);

   123 

   124 public:

   125   // Node layout (parallels RegionNode):

   126   enum { Region,                // Control input is the Phi's region.

   127          Input                  // Input values are [1..len)

   128   };

   129 

   130   PhiNode( Node *r, const Type *t, const TypePtr* at = NULL )

   131     : TypeNode(t,r->req()), _adr_type(at) {

   132     init_class_id(Class_Phi);

   133     init_req(0, r);

   134     verify_adr_type();

   135   }

   136   // create a new phi with in edges matching r and set (initially) to x

   137   static PhiNode* make( Node* r, Node* x );

   138   // extra type arguments override the new phi's bottom_type and adr_type

   139   static PhiNode* make( Node* r, Node* x, const Type *t, const TypePtr* at = NULL );

   140   // create a new phi with narrowed memory type

   141   PhiNode* slice_memory(const TypePtr* adr_type) const;

   142   // like make(r, x), but does not initialize the in edges to x

   143   static PhiNode* make_blank( Node* r, Node* x );

   144 

   145   // Accessors

   146   RegionNode* region() const { Node* r = in(Region); assert(!r || r->is_Region(), ""); return (RegionNode*)r; }

   147 

   148   Node* is_copy() const {

   149     // The node is a real phi if _in[0] is a Region node.

   150     DEBUG_ONLY(const Node* r = _in[Region];)

   151     assert(r != NULL && r->is_Region(), "Not valid control");

   152     return NULL;  // not a copy!

   153   }

   154 

   155   // Check for a simple dead loop.

   156   enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };

   157   LoopSafety simple_data_loop_check(Node *in) const;

   158   // Is it unsafe data loop? It becomes a dead loop if this phi node removed.

   159   bool is_unsafe_data_reference(Node *in) const;

   160   int  is_diamond_phi() const;

   161   virtual int Opcode() const;

   162   virtual bool pinned() const { return in(0) != 0; }

   163   virtual const TypePtr *adr_type() const { verify_adr_type(true); return _adr_type; }

   164   virtual const Type *Value( PhaseTransform *phase ) const;

   165   virtual Node *Identity( PhaseTransform *phase );

   166   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);

   167   virtual const RegMask &out_RegMask() const;

   168   virtual const RegMask &in_RegMask(uint) const;

   169 #ifndef PRODUCT

   170   virtual void dump_spec(outputStream *st) const;

   171 #endif

   172 #ifdef ASSERT

   173   void verify_adr_type(VectorSet& visited, const TypePtr* at) const;

   174   void verify_adr_type(bool recursive = false) const;

   175 #else //ASSERT

   176   void verify_adr_type(bool recursive = false) const {}

   177 #endif //ASSERT

   178 };

   179 

   180 //------------------------------GotoNode---------------------------------------

   181 // GotoNodes perform direct branches.

   182 class GotoNode : public Node {

   183 public:

   184   GotoNode( Node *control ) : Node(control) {

   185     init_flags(Flag_is_Goto);

   186   }

   187   virtual int Opcode() const;

   188   virtual bool pinned() const { return true; }

   189   virtual bool  is_CFG() const { return true; }

   190   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash

   191   virtual const Node *is_block_proj() const { return this; }

   192   virtual bool depends_only_on_test() const { return false; }

   193   virtual const Type *bottom_type() const { return Type::CONTROL; }

   194   virtual const Type *Value( PhaseTransform *phase ) const;

   195   virtual Node *Identity( PhaseTransform *phase );

   196   virtual const RegMask &out_RegMask() const;

   197 };

   198 

   199 //------------------------------CProjNode--------------------------------------

   200 // control projection for node that produces multiple control-flow paths

   201 class CProjNode : public ProjNode {

   202 public:

   203   CProjNode( Node *ctrl, uint idx ) : ProjNode(ctrl,idx) {}

   204   virtual int Opcode() const;

   205   virtual bool  is_CFG() const { return true; }

   206   virtual uint hash() const { return NO_HASH; }  // CFG nodes do not hash

   207   virtual const Node *is_block_proj() const { return in(0); }

   208   virtual const RegMask &out_RegMask() const;

   209   virtual uint ideal_reg() const { return 0; }

   210 };

   211 

   212 //---------------------------MultiBranchNode-----------------------------------

   213 // This class defines a MultiBranchNode, a MultiNode which yields multiple

   214 // control values. These are distinguished from other types of MultiNodes

   215 // which yield multiple values, but control is always and only projection #0.

   216 class MultiBranchNode : public MultiNode {

   217 public:

   218   MultiBranchNode( uint required ) : MultiNode(required) {

   219     init_class_id(Class_MultiBranch);

   220   }

   221 };

   222 

   223 //------------------------------IfNode-----------------------------------------

   224 // Output selected Control, based on a boolean test

   225 class IfNode : public MultiBranchNode {

   226   // Size is bigger to hold the probability field.  However, _prob does not

   227   // change the semantics so it does not appear in the hash & cmp functions.

   228   virtual uint size_of() const { return sizeof(*this); }

   229 public:

   230 

   231   // Degrees of branch prediction probability by order of magnitude:

   232   // PROB_UNLIKELY_1e(N) is a 1 in 1eN chance.

   233   // PROB_LIKELY_1e(N) is a 1 - PROB_UNLIKELY_1e(N)

   234 #define PROB_UNLIKELY_MAG(N)    (1e- ## N ## f)

   235 #define PROB_LIKELY_MAG(N)      (1.0f-PROB_UNLIKELY_MAG(N))

   236 

   237   // Maximum and minimum branch prediction probabilties

   238   // 1 in 1,000,000 (magnitude 6)

   239   //

   240   // Although PROB_NEVER == PROB_MIN and PROB_ALWAYS == PROB_MAX

   241   // they are used to distinguish different situations:

   242   //

   243   // The name PROB_MAX (PROB_MIN) is for probabilities which correspond to

   244   // very likely (unlikely) but with a concrete possibility of a rare

   245   // contrary case.  These constants would be used for pinning

   246   // measurements, and as measures for assertions that have high

   247   // confidence, but some evidence of occasional failure.

   248   //

   249   // The name PROB_ALWAYS (PROB_NEVER) is to stand for situations for which

   250   // there is no evidence at all that the contrary case has ever occurred.

   251 

   252 #define PROB_NEVER              PROB_UNLIKELY_MAG(6)

   253 #define PROB_ALWAYS             PROB_LIKELY_MAG(6)

   254 

   255 #define PROB_MIN                PROB_UNLIKELY_MAG(6)

   256 #define PROB_MAX                PROB_LIKELY_MAG(6)

   257 

   258   // Static branch prediction probabilities

   259   // 1 in 10 (magnitude 1)

   260 #define PROB_STATIC_INFREQUENT  PROB_UNLIKELY_MAG(1)

   261 #define PROB_STATIC_FREQUENT    PROB_LIKELY_MAG(1)

   262 

   263   // Fair probability 50/50

   264 #define PROB_FAIR               (0.5f)

   265 

   266   // Unknown probability sentinel

   267 #define PROB_UNKNOWN            (-1.0f)

   268 

   269   // Probability "constructors", to distinguish as a probability any manifest

   270   // constant without a names

   271 #define PROB_LIKELY(x)          ((float) (x))

   272 #define PROB_UNLIKELY(x)        (1.0f - (float)(x))

   273 

   274   // Other probabilities in use, but without a unique name, are documented

   275   // here for lack of a better place:

   276   //

   277   // 1 in 1000 probabilities (magnitude 3):

   278   //     threshold for converting to conditional move

   279   //     likelihood of null check failure if a null HAS been seen before

   280   //     likelihood of slow path taken in library calls

   281   //

   282   // 1 in 10,000 probabilities (magnitude 4):

   283   //     threshold for making an uncommon trap probability more extreme

   284   //     threshold for for making a null check implicit

   285   //     likelihood of needing a gc if eden top moves during an allocation

   286   //     likelihood of a predicted call failure

   287   //

   288   // 1 in 100,000 probabilities (magnitude 5):

   289   //     threshold for ignoring counts when estimating path frequency

   290   //     likelihood of FP clipping failure

   291   //     likelihood of catching an exception from a try block

   292   //     likelihood of null check failure if a null has NOT been seen before

   293   //

   294   // Magic manifest probabilities such as 0.83, 0.7, ... can be found in

   295   // gen_subtype_check() and catch_inline_exceptions().

   296 

   297   float _prob;                  // Probability of true path being taken.

   298   float _fcnt;                  // Frequency counter

   299   IfNode( Node *control, Node *b, float p, float fcnt )

   300     : MultiBranchNode(2), _prob(p), _fcnt(fcnt) {

   301     init_class_id(Class_If);

   302     init_req(0,control);

   303     init_req(1,b);

   304   }

   305   virtual int Opcode() const;

   306   virtual bool pinned() const { return true; }

   307   virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }

   308   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);

   309   virtual const Type *Value( PhaseTransform *phase ) const;

   310   virtual const RegMask &out_RegMask() const;

   311   void dominated_by(Node* prev_dom, PhaseIterGVN* igvn);

   312   int is_range_check(Node* &range, Node* &index, jint &offset);

   313   static Node* up_one_dom(Node* curr, bool linear_only = false);

   314 

   315 #ifndef PRODUCT

   316   virtual void dump_spec(outputStream *st) const;

   317 #endif

   318 };

   319 

   320 class IfTrueNode : public CProjNode {

   321 public:

   322   IfTrueNode( IfNode *ifnode ) : CProjNode(ifnode,1) {

   323     init_class_id(Class_IfTrue);

   324   }

   325   virtual int Opcode() const;

   326   virtual Node *Identity( PhaseTransform *phase );

   327 };

   328 

   329 class IfFalseNode : public CProjNode {

   330 public:

   331   IfFalseNode( IfNode *ifnode ) : CProjNode(ifnode,0) {

   332     init_class_id(Class_IfFalse);

   333   }

   334   virtual int Opcode() const;

   335   virtual Node *Identity( PhaseTransform *phase );

   336 };

   337 

   338 

   339 //------------------------------PCTableNode------------------------------------

   340 // Build an indirect branch table.  Given a control and a table index,

   341 // control is passed to the Projection matching the table index.  Used to

   342 // implement switch statements and exception-handling capabilities.

   343 // Undefined behavior if passed-in index is not inside the table.

   344 class PCTableNode : public MultiBranchNode {

   345   virtual uint hash() const;    // Target count; table size

   346   virtual uint cmp( const Node &n ) const;

   347   virtual uint size_of() const { return sizeof(*this); }

   348 

   349 public:

   350   const uint _size;             // Number of targets

   351 

   352   PCTableNode( Node *ctrl, Node *idx, uint size ) : MultiBranchNode(2), _size(size) {

   353     init_class_id(Class_PCTable);

   354     init_req(0, ctrl);

   355     init_req(1, idx);

   356   }

   357   virtual int Opcode() const;

   358   virtual const Type *Value( PhaseTransform *phase ) const;

   359   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);

   360   virtual const Type *bottom_type() const;

   361   virtual bool pinned() const { return true; }

   362 };

   363 

   364 //------------------------------JumpNode---------------------------------------

   365 // Indirect branch.  Uses PCTable above to implement a switch statement.

   366 // It emits as a table load and local branch.

   367 class JumpNode : public PCTableNode {

   368 public:

   369   JumpNode( Node* control, Node* switch_val, uint size) : PCTableNode(control, switch_val, size) {

   370     init_class_id(Class_Jump);

   371   }

   372   virtual int   Opcode() const;

   373   virtual const RegMask& out_RegMask() const;

   374   virtual const Node* is_block_proj() const { return this; }

   375 };

   376 

   377 class JumpProjNode : public JProjNode {

   378   virtual uint hash() const;

   379   virtual uint cmp( const Node &n ) const;

   380   virtual uint size_of() const { return sizeof(*this); }

   381 

   382  private:

   383   const int  _dest_bci;

   384   const uint _proj_no;

   385   const int  _switch_val;

   386  public:

   387   JumpProjNode(Node* jumpnode, uint proj_no, int dest_bci, int switch_val)

   388     : JProjNode(jumpnode, proj_no), _dest_bci(dest_bci), _proj_no(proj_no), _switch_val(switch_val) {

   389     init_class_id(Class_JumpProj);

   390   }

   391 

   392   virtual int Opcode() const;

   393   virtual const Type* bottom_type() const { return Type::CONTROL; }

   394   int  dest_bci()    const { return _dest_bci; }

   395   int  switch_val()  const { return _switch_val; }

   396   uint proj_no()     const { return _proj_no; }

   397 #ifndef PRODUCT

   398   virtual void dump_spec(outputStream *st) const;

   399 #endif

   400 };

   401 

   402 //------------------------------CatchNode--------------------------------------

   403 // Helper node to fork exceptions.  "Catch" catches any exceptions thrown by

   404 // a just-prior call.  Looks like a PCTableNode but emits no code - just the

   405 // table.  The table lookup and branch is implemented by RethrowNode.

   406 class CatchNode : public PCTableNode {

   407 public:

   408   CatchNode( Node *ctrl, Node *idx, uint size ) : PCTableNode(ctrl,idx,size){

   409     init_class_id(Class_Catch);

   410   }

   411   virtual int Opcode() const;

   412   virtual const Type *Value( PhaseTransform *phase ) const;

   413 };

   414 

   415 // CatchProjNode controls which exception handler is targetted after a call.

   416 // It is passed in the bci of the target handler, or no_handler_bci in case

   417 // the projection doesn't lead to an exception handler.

   418 class CatchProjNode : public CProjNode {

   419   virtual uint hash() const;

   420   virtual uint cmp( const Node &n ) const;

   421   virtual uint size_of() const { return sizeof(*this); }

   422 

   423 private:

   424   const int _handler_bci;

   425 

   426 public:

   427   enum {

   428     fall_through_index =  0,      // the fall through projection index

   429     catch_all_index    =  1,      // the projection index for catch-alls

   430     no_handler_bci     = -1       // the bci for fall through or catch-all projs

   431   };

   432 

   433   CatchProjNode(Node* catchnode, uint proj_no, int handler_bci)

   434     : CProjNode(catchnode, proj_no), _handler_bci(handler_bci) {

   435     init_class_id(Class_CatchProj);

   436     assert(proj_no != fall_through_index || handler_bci < 0, "fall through case must have bci < 0");

   437   }

   438 

   439   virtual int Opcode() const;

   440   virtual Node *Identity( PhaseTransform *phase );

   441   virtual const Type *bottom_type() const { return Type::CONTROL; }

   442   int  handler_bci() const        { return _handler_bci; }

   443   bool is_handler_proj() const    { return _handler_bci >= 0; }

   444 #ifndef PRODUCT

   445   virtual void dump_spec(outputStream *st) const;

   446 #endif

   447 };

   448 

   449 

   450 //---------------------------------CreateExNode--------------------------------

   451 // Helper node to create the exception coming back from a call

   452 class CreateExNode : public TypeNode {

   453 public:

   454   CreateExNode(const Type* t, Node* control, Node* i_o) : TypeNode(t, 2) {

   455     init_req(0, control);

   456     init_req(1, i_o);

   457   }

   458   virtual int Opcode() const;

   459   virtual Node *Identity( PhaseTransform *phase );

   460   virtual bool pinned() const { return true; }

   461   uint match_edge(uint idx) const { return 0; }

   462   virtual uint ideal_reg() const { return Op_RegP; }

   463 };

   464 

   465 //------------------------------NeverBranchNode-------------------------------

   466 // The never-taken branch.  Used to give the appearance of exiting infinite

   467 // loops to those algorithms that like all paths to be reachable.  Encodes

   468 // empty.

   469 class NeverBranchNode : public MultiBranchNode {

   470 public:

   471   NeverBranchNode( Node *ctrl ) : MultiBranchNode(1) { init_req(0,ctrl); }

   472   virtual int Opcode() const;

   473   virtual bool pinned() const { return true; };

   474   virtual const Type *bottom_type() const { return TypeTuple::IFBOTH; }

   475 

   476   virtual void emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const { }

   477   virtual uint size(PhaseRegAlloc *ra_) const { return 0; }

   478 #ifndef PRODUCT

   479   virtual void format( PhaseRegAlloc *, outputStream *st ) const;

   480 #endif

   481 };