Initial revision

[libfirm] / ir / ir / ircons.h

/* Copyright (C) 1998 - 2000 by Universitaet Karlsruhe
** All rights reserved.
**
** Authors: Martin Trapp, Christian Schaefer,
**          Goetz Lindenmaier
**
** ircons.h ir node construction
*/


/** !!!
*** Ideas for improvement:
***
 Handle construction of exceptions more comfortable:
 Add new constructors that pass the exception region (or better the
 Phi for the memories, the ex. region can be found from there) as parameter,
 constructor then adds all Proj nodes and returns the pointer
 to the Proj node that selects the result of the arithmetic operation.

 Maybe hide the exception region in a global variable, especially if
 it is always unambiguous.
**/


/**
***  IRCONS

  This file documents all datatypes and constructors needed to
  build a FIRM representation of a pocedure.  The constructors are
  also implemented in this file.

  The documentation also gives a short manual how to use the library.

  For extensive documentation of FIRM see UKA Techreport 1999-14.

  DATATYPES
  =========

  The struct ir_graph
  -------------------

    This struct contains all information about a procedure.
    It's allocated directly to memory.

    The fields of ir_graph:

    *ent             The entity describing this procedure.

    The beginning and end of a graph:

    *start_block     This ir_node is the block that contains the unique
                     start node of the procedure.  With it it contains
                     the Proj's on starts results.
                     Further all Const nodes are placed in the start block.
    *start           This ir_node is the unique start node of the procedure.

    *end_block       This ir_node is the block that contains the unique
                     end node of the procedure.  This block contains no
                     further nodes.
    *end             This ir_node is the unique end node of the procedure.

    The following nodes are Projs from the start node, held in ir_graph for
    simple access:

    *frame           The ir_node producing the pointer to the stack frame of the
                     procedure as output.  This is the Proj node on the third
                     output of the start node.  This output of the start node
                     is tagged as pns_frame_base.  In FIRM most lokal
                     variables are modeled as data flow edges.  Static
                     allocated arrays can not be represented as dataflow
                     edges. Therefore FIRM has to represent them in the stack
                     frame.

    *globals         This models a pointer to a  space in the memory where _all_
                     global things are held.  Select from this pointer with a Sel
                     node the pointer to a global variable / procedure / compiler
                     known function... .

    *args            The ir_node that produces the arguments of the method as it's
                     result.  This is a Proj node on the fourth output of the start
                     node.  This output is tagged as pns_args.

    *bad             The bad node is an auxiliary node. It is needed only once,
                     so there is this globally reachable node.

    Datastructures that are private to a graph:

    *obst            An obstack that contains all nodes.

    *current_block   A pointer to the current block.  Any node created with one
                     of the node constructors (new_<opcode>) are assigned to this
                     block.  It can be set with switch_block(block).  Only needed
                     for ir construction.

    params/n_loc     An int giving the number of local variables in this procedure.
                     This is neede for ir construction. Name will be changed.

    *value_table     This pset is used for global value numbering for optimizing
                     use in iropt.c.

    *Phi_in_stack;   a stack needed for automatic Phi construction, needed only
                     during ir construction.


  Three kinds of nodes
  --------------------

    There are three kinds of nodes known to the ir:  enties,
    types, and ir_nodes

    + ir_nodes are the actual nodes of the FIRM intermediate representation.
      They represent operations on the data of the program and control flow
      operations.

    + entity ==> implemented in entity.h
      Refers to a single entity of the compiled program, e.g. a field of a class or
      a method.

    + types ==> implemented in type.h
      With types type information is represented.  There are several type nodes.

  Implementation of the FIRM operations: ir_node
  ----------------------------------------------

    Ir_nodes represent operations on the data of the program and control flow
    operations.  Examples of ir_nodes:  Add, Jmp, Cmp

    FIRM is a dataflow graph.  A dataflow graph is a directed graph,
    so that every node has incoming and outgoing edges.  A node is
    executable if every input at it's incoming edges is available.
    Execution of the dataflow graph is started at the Start node which
    has no incoming edges and ends when the End node executes, even if
    there are still executable or not executed nodes.  (Is this true,
    or must all executable nodes be executed?)  (There are exceptions
    to the dataflow paradigma that all inputs have to be available
    before a node can execute: Phi, Block.  See UKA Techreport
    1999-14.)

    The implementation of FIRM differs from the view as a dataflow
    graph.  To allow fast traversion of the graph edges are
    implemented as C-pointers.  Inputs to nodes are not ambiguous, the
    results can be used by several other nodes.  Each input can be
    implemented as a single pointer to a predecessor node, outputs
    need to be lists of pointers to successors.  Therefore a node
    contains pointers to it's predecessor so that the implementation is a
    dataflow graph with reversed edges.  It has to be traversed bottom
    up.

    All nodes of the ir have the same basic structure.  They are
    distinguished by a field containing the opcode.

    The fields of an ir_node:

    kind             A firm_kind tag containing k_ir_node.  This is useful for
                     dynamically checking the type of a node.

    *op              This ir_op gives the opcode as a tag and a string
                     and the number of attributes of an ir_node.  There is
                     one statically allocated struct ir_op for each opcode.

    *mode            The ir_mode of the operation represented by this firm node.
                     The mode of the operation is the mode of it's result.  A Firm
                     mode is a datatype as known to the target, not a type of the
                     source language.

    visit            A flag for traversing the ir.

    **in             An array with pointers to the node's predecessors.

    *link            A pointer to an ir_node.  With this pointer all Phi nodes
                     are attached to a Block, i.e., a Block points to it's
                     first Phi node, this node points to the second Phi node
                     in the Block and so fourth.  Used in mature_block
                     to find all Phi nodes to be matured.  It's also used to
                     annotate a node with a better, optimized version of it.

    attr             An attr struct containing the attributes of the nodes. The
                     attributes depend on the opcode of the node.  The number of
                     these attributes is given in op.

  The struct ir_op
  ----------------
                     Not yet documented. See irop.h.

  The struct ir_mode
  ------------------
                     Not yet documented. See irmode.h.

  GLOBAL VARIABLES
  ================

  current_ir_graph   Points to the current ir_graph.  All constructors for nodes
                     add nodes to this graph.

  ir_visited         A int used as flag to traverse the ir_graph.

  block_visited      A int used as a flag to traverse block nodes in the graph.

                     Others not yet documented.




  CONSTRUCTOR FOR IR_GRAPH
  ========================

  ir_graph *new_ir_graph (entity *ent, int params);
  -------------------------------------------------

  This constructor generates the basic infrastructure needed to
  represent a procedure in FIRM.

  The parameters of new_ir_graph are:

    *ent             A pointer to an entity representing the procedure.

    params           An integer giving the number of local variables in the
                     procedure.

  It allocates an ir_graph and sets current_ir_graph to point to this
  graph.  Further it allocates the following nodes needed for every
  procedure:

  * The start block containing a start node and Proj nodes for it's
    four results (X, M, P, T).
  * The end block containing an end node. This block is not matured
    after executing new_ir_graph as predecessors need to be added to it.
    (Maturing a block means fixing it's number of predecessors.)
  * The current block, which is empty and also not matured.

  Further it enters the global store into the datastructure of the start
  block that contanis all valid values in this block (set_store()).  This
  datastructure is used to build the Phi nodes and removed after completion
  of the graph.
  There is no path from end to start in the graph after calling ir_graph.


  IR_NODES AND CONSTRUCTORS FOR IR_NODES
  =======================================

  All ir_nodes are defined by a common data structure.  They are distinguished
  by their opcode and differ in the number of their attributes.

  The constructor for the block node sets current_block to itself.
  Const nodes are always added to the start block.
  All other constructors add the created node to the current_block.
  swich_block(block) allows to set the current block to block.

  Watch for my inconsistent use of input and predecessor (dataflow view)
  and `the node points to' (implementation view).

  The following description of the nodes lists four properties them if these are
  of interest:
   - the parameters to the constructor
   - the inputs of the Firm node
   - the outputs of the Firm node
   - attributes to the node


  BASIC BLOCKS
  ------------

  ir_node *new_Block (void)
  --------------------------

  Creates a new block.  Sets current_block to itself.  When a new block is
  created it cannot be known how many predecessors this block will have in the
  control flow graph. Therefore the list of inputs can not be fixed at
  creation.  Predecessors can be added with add_in_edge (block, control flow
  operation).  With every added predecessor the number of inputs to Phi nodes
  also changes.

  The block can be completed by mature_block(block) if all predecessors are
  known.  If several blocks are built at once, mature_block can only be called
  after set_value has been called for all values that are life at the end
  of the block.  This is necessary so that Phi nodes created by mature_block
  get the right predecessors in case of cyclic dependencies.  If all set_values
  of this block are called after maturing it and before calling get_value
  in some block that is control flow dependent on this block, the construction
  is correct.
  Example for faulty ir construction:
    block_before_loop = new_block();
    set_value(x);
    mature_block(block_before_loop);
    before2header = new_Jmp;

    loop_header = new_block ();
    header2body - new_Jmp();

    loop_body = new_block ();
    body2header = new_Jmp();

    add_in_edge(loop_header, before2header);
    add_in_edge(loop_header, body2header);
    add_in_edge(loop_body, header2body);

    mature_block(loop_header);
    mature_block(loop_body);

    get_value(loop_body, x);   // gets the Phi in loop_header
    set_value(loop_header, x); // sets the value the above get_value should
                               // have returned!!!
  Mature_block also fixes the number of inputs to the Phi nodes.  Mature_block
  should be called as early as possible, as afterwards the generation of Phi
  nodes is more efficient.

  Inputs:
    There is an input for each control flow predecessor of the block.
    The input points to an instruction producing an output of type X.
    Possible predecessors:  Start, Jmp, Cond, Raise or Return or any node
    possibly causing an exception.  (Often the real predecessors are Projs.)
  Output:
    Mode R, all nodes belonging to this block should consume this output.
    As they are strict (except Block and Phi node) it is a necessary condition
    that the block node executed before any other node in this block
    executes.
  Attributes:
    block.matured  Indicates whether the block is mature.
    block.closed   ???
    block.**graph_arr
                    This attribute contains all local values valid in this
                    block. This is needed to build the Phi nodes and removed
                    if the graph is complete.


  CONTROL FLOW OPERATIONS
  -----------------------

  In each block there must be exactly one of the control flow
  operations Start, End, Jmp, Cond, Return or Raise.  The output of a
  control flow operation points to the block to be executed next.

  ir_node *new_Start (void)
  -------------------------

  Creates a start node.  Not actually needed public.  Created
  by new_ir_graph.

  Inputs:
    No inputs except the block it belogns to.
  Output:
    A tuple of 4 (5, 6) distinct values. These are labeled by the following
    projection numbers (pns_number):
    * pns_initial_exec
                     mode X, points to the first block to be executed.
    * pns_global_store
                     mode M, the global store
    * pns_frame_base mode P, a pointer to the base of the procedures stack frame.
    * pns_globals    mode P, a pointer to the part of the memory containing _all_
                             global things.
    * pns_args       mode T, a tuple containing all arguments of the procedure.


  ir_node *new_End (void)
  -----------------------

  Creates an end node.  Not actually needed public.  Created by
  new_ir_graph.

  Inputs:
    No inputs except the block it belogns to.
  Output:
    No output.

  ir_node *new_Jmp (void)
  -----------------------

  Creates a Jmp node.

  Inputs:
    The block the node belongs to
  Output:
    Control flow to the next block.

  ir_node *new_Cond (ir_node *c)
  ------------------------------

  Creates a Cond node.  There are two versions of this node.

  The Boolean Cond:
  Input:
    A value of mode b.
  Output:
    A tuple of two control flows.  The first is taken if the input is
    false, the second if it is true.

  The Switch Cond:
  Input:
    A value of mode I_u. (i)
  Output:
    A tuple of n control flows.  If the Cond's input is i, control
    flow will procede along output i. If the input is >= n control
    flow proceeds along output n.

  ir_node *new_Return (in_node *store, int arity, ir_node **in)
  -------------------------------------------------------------

  The return node has as inputs the results of the procedure.  It
  passes the control flow to the end_block.

  Inputs:
    The memory state.
    All results.
  Output
    Control flow to the end block.

  ir_node *new_Raise (ir_node *store, ir_node *obj)
  -------------------------------------------------

  Raises an exception.  Unconditional change of control flow.  Writes
  an explicit Except variable to memory to pass it to the exception
  handler.  See TechReport 1999-14, chapter Exceptions.

  Inputs:
    The memory state.
    A pointer to the Except variable.
  Output:
    A tuple of control flow and the changed memory state.  The control flow
    points to the exception handler if it is definied in this procedure,
    else it points to the end_block.


  CONSTANTS
  ---------

  ir_node *new_Const (ir_mode *mode, tarval *con)
  -----------------------------------------------

  Creates a constant in the constant table and adds a Const node
  returning this value to the start block.

  Parameters:
    *mode            The mode of the constant.
    *con             Points to an entry in the constant table.
                     This pointer is added to the attributes of
                     the node (self->attr.con)
  Inputs:
    No inputs except the block it belogns to.
  Output:
    The constant value.
  Attribute:
    attr.con   A tarval* pointer to the proper entry in the constant
               table.

  ir_node *new_SymConst (type *type, symconst_kind kind)
  ------------------------------------------------------------

  There are two kinds of symbolic constants:
    type_tag  The symbolic constant represents a type tag.
    size      The symbolic constant represents the size of a class.
    link_info Information for the linker.

  Parameters
    kind       The kind of the symbolic constant: type_tag or size.
    *type      Points to the type the tag stands for or to the type
               whose size is represented by the constant.

  Inputs:
    No inputs except the block it belogns to.
  Output:
    An unsigned integer (I_u) or a pointer (P).

  Attributes:
    attr.i.num       The symconst_kind, i.e. one of
                      - type_tag
                      - size
                      - linkage_ptr_info
      If the attr.i.num is type_tag of size, the node contains an attribute
    attr.i.*type     A pointer to a type_class.
      if it is linkage_ptr_info it contains
    attr.i.*ptrinfo  A ident holding information for the linker.

  THE SELECT NODE
  ---------------

  ir_node *new_simpleSel (ir_node *store, ir_node *frame, entity *sel)
  --------------------------------------------------------------------


  Selects an entity from a compound type. This entity can be a field or
  a method.

  Parameters:
    *store     The memory in which the object the entity should be selected from
               is allocated.
    *frame     The pointer to the object.
    *sel       The entity to select.

  Inputs:
    The memory containing the object.
    A pointer to the object.
    An unsigned integer.
  Output:
    A pointer to the selected entity.
  Attributes:
    attr.sel   Pointer to the entity


  ir_node *new_Sel (ir_node *store, ir_node *frame, int arity, ir_node **in,
  --------------------------------------------------------------------------
                    entity *sel)
                    ------------

  Selects a field from an array type.  The entity has as owner the array, as
  type the arrays element type.  The indexes to access an array element are
  given also.

  Parameters:
    *store     The memory in which the object the entity should be selected from
               is allocated.
    *frame     The pointer to the object.
    *arity     number of array indexes.
    *in        array with index inputs to the node.
    *sel       The entity to select.

  Inputs:
    The memory containing the object.
    A pointer to the object.
    As much unsigned integer as there are array expressions.
  Output:
    A pointer to the selected entity.
  Attributes:
    attr.sel   Pointer to the entity

  The constructors new_Sel and new_simpleSel generate the same ir nodes.
  simpleSel just sets the arity of the index inputs to zero.


  ARITHMETIC OPERATIONS
  ---------------------

  ir_node *new_Call (ir_node *store, ir_node *callee, int arity, ir_node **in,
  ----------------------------------------------------------------------------
                     type_method *type)
                     ------------------

  Creates a procedure call.

  Parameters
    *store           The actual store.  Why not also the stack frame?
    *callee          A pointer to the called procedure.
    arity            The number of procedure parameters.
    **in             An array with the pointers to the parameters.
                     This array is copied in the constructor.
    *type            Type information of the procedure called.

  Inputs:
    The store, the callee and the parameters.
  Output:
    A tuple containing the eventually changed store and the procedure
    results.
  Attributes:
    attr.call        Contains the type information for the procedure.

  ir_node *new_Add (ir_node *op1, ir_node *op2, ir_mode *mode)
  ------------------------------------------------------------

  Trivial.

  ir_node *new_Sub (ir_node *op1, ir_node *op2, ir_mode *mode)
  ------------------------------------------------------------

  Trivial.

  ir_node *new_Minus (ir_node *op, ir_mode *mode)
  -----------------------------------------------

  This constructor is for unary Minus operations on floating point
  values.  Such a Minus can trap if it is implemented as a Sub from
  zero due to rounding errors.

  ir_node *new_Mul (ir_node *op1, ir_node *op2, ir_mode *mode)
  ------------------------------------------------------------

  Trivial.

  ir_node *new_Quot (ir_node *memop, ir_node *op1, ir_node *op2)
  --------------------------------------------------------------

  Quot performs exact division of floating point numbers.  It's mode
  is Tuple, the mode of the result must be annotated to the Proj
  that extracts the result of the arithmetic operations.

  Inputs:
    The store needed to model exceptions and the two operands.
  Output:
    A tuple contaning a memory and a execution for modeling exceptions
    and the result of the arithmetic operation.

  ir_node *new_DivMod (ir_node *memop, ir_node *op1, ir_node *op2)
  ----------------------------------------------------------------

  Performs Div and Mod on interger values.

  Output:
    A tuple contaning a memory and a execution for modeling exceptions
    and the two result of the arithmetic operations.

  ir_node *new_Div (ir_node *memop, ir_node *op1, ir_node *op2)
  -------------------------------------------------------------

  Trivial.

  ir_node *new_Mod (ir_node *memop, ir_node *op1, ir_node *op2)
  -------------------------------------------------------------

  Trivial.

  ir_node *new_Abs (ir_node *op, ir_mode *mode)
  ---------------------------------------------

  Trivial.

  ir_node *new_And (ir_node *op1, ir_node *op2, ir_mode *mode)
  ------------------------------------------------------------

  Trivial.

  ir_node *new_Or (ir_node *op1, ir_node *op2, ir_mode *mode)
  -----------------------------------------------------------

  Trivial.

  ir_node *new_Eor (ir_node *op1, ir_node *op2, ir_mode *mode)
  ------------------------------------------------------------

  Trivial.

  ir_node *new_Not (ir_node *op, ir_mode *mode)
  ---------------------------------------------

  This node constructs a constant where all bits are set to one
  and a Eor of this constant and the operator.  This simulates a
  Not operation.

  ir_node *new_Shl (ir_node *op, ir_node *k, ir_mode *mode)
  ---------------------------------------------------------

  Trivial.

  ir_node *new_Shr (ir_node *op, ir_node *k, ir_mode *mode)
  ---------------------------------------------------------

  Logic shift right, i.e., zero extended.


  ir_node *new_Shrs (ir_node *op, ir_node *k, ir_mode *mode)
  ----------------------------------------------------------

  Arithmetic shift right, i.e., sign extended.

  ir_node *new_Rot (ir_node *op, ir_node *k, ir_mode *mode)
  ---------------------------------------------------------

  Rotates the operand to the (right??) by k bits.

  ir_node *new_Conv (ir_node *op, ir_mode *mode)
  ---------------------------------------------

  Mode conversion.  For allowed conversions see UKA Tech Report
  1999-14.

  ir_node *new_Cmp (ir_node *op1, ir_node *op2)
  ---------------------------------------------

  Input:
    The two values to be compared.
  Output:
    A 16-tuple containing the results of the 16 different comparisons.
    The following is a list giving the comparisons and a projection
    number (pnc_number) to use in Proj nodes to extract the proper result.
      False     false
      Eq        equal
      Lt        less
      Le        less or equal
      Gt        greater
      Ge        greater of equal
      Lg        less or greater
      Leg       less, equal or greater = ordered
      Uo        unordered
      Ue        unordered or equal
      Ul        unordered or less
      Ule       unordered, less or equal
      Ug        unordered or greater
      Uge       unordered, greater or equal
      Ne        unordered, less or greater = not equal
      True      true



  THE PHI NODE
  ------------

  In general, Phi nodes are automaitcally inserted.  In some cases, if
  all predecessors of a block are known, an explicit Phi node constructor
  is needed.  E.g., to construct a FIRM graph for a statement as
    a = (b==c) ? 2 : 5;

  ir_node *new_Phi (int arity, ir_node **in, ir_mode *mode)
  ---------------------------------------------------------

  Creates a Phi node. The in's order has to correspond to the order
  of in's of current_block.  This is not checked by the library!

  Parameter
    arity            number of predecessors
    **in             array with predecessors
    *mode            The mode of it's inputs and output.
  Inputs:
    A Phi node has as many inputs as the block it belongs to.
    Each input points to a definition of the same value on a
    different path in the control flow.
  Output
    The definition valid in this block.


  OPERATIONS TO MANAGE MEMORY EXPLICITLY
  --------------------------------------

  ir_node *new_Load (ir_node *store, ir_node *addr)
  ----------------------------------------------------------------

  The Load operation reads a value from memory.

  Parameters:
  *store        The current memory.
  *addr         A pointer to the variable to be read in this memory.
  *mode         The mode of the loaded value.

  Inputs:
    The memory and a pointer to a variable in this memory.
  Output:
    A tuple of the memory, a control flow to be taken in case of
    an exception and the loaded value.

  ir_node *new_Store (ir_node *store, ir_node *addr, ir_node *val)
  ----------------------------------------------------------------

  The Store operation writes a value to a variable in memory.

  Inputs:
    The memory, a pointer to a variable in this memory and the value
    to write to this variable.
  Output:
    A tuple of the changed memory and a control flow to be taken in
    case of an exception.

  ir_node *new_Alloc (ir_node *store, ir_node *size, type *alloc_type,
  --------------------------------------------------------------------
                      where_alloc where)
                      ------------------

  The Alloc node allocates a new variable.  It can be specified whether the
  variable should be allocated to the stack or to the heap.

  Parameters:
    *store       The memory which shall contain the new variable.
    **    *size        The number of bytes to allocate. Old. **
    *size        We decided that the size easily can be derived from the type.
                 This field is for allocating arrays, i.e., it gives the multiple
                 of the size of alloc_type to allocate memory for.
    *alloc_type  The type of the allocated variable.
    where        Where to allocate the variable, either heap_alloc or stack_alloc.

  Inputs:
    A memory and an unsigned integer.
  Output:
    A tuple of the changed memory, a control flow to be taken in
    case of an exception and the pointer to the new variable.
  Attributes:
    a.where          Indicates where the variable is allocated.
    a.*type          A pointer to the class the allocated data object
                     belongs to.

  ir_node *new_Free (ir_node *store, ir_node *ptr, type *free_type)
  ------------------------------------------------------------------

  The Free node frees memory of the given variable.

  Parameters:
    *store       The memory which shall contain the new variable.
    *ptr         The pointer to the object to free.
    *size        The number of objects of type free_type to free in a sequence.
    *free_type   The type of the freed variable.

  Inputs:
    A memory, a pointer and an unsigned integer.
  Output:
    The changed memory.
  Attributes:
    f.*type          A pointer to the type information of the freed data object.

  Not Implemented!

  ir_node *new_Sync (int arity, ir_node **in)
  -------------------------------------------

  The Sync operation unifies several partial memory blocks.  These blocks
  have to be pairwise disjunct or the values in common locations have to
  be identical.  This operation allows to specify all operations that eventually
  need several partial memory blocks as input with a single entrance by
  unifying the memories with a preceding Sync operation.

  Parameters
    arity    The number of memories to syncronize.
    **in     An array of pointers to nodes that produce an output of
             type memory.
  Inputs
    Several memories.
  Output
    The unified memory.


  SPECIAL OPERATIONS
  ------------------

  ir_node *new_Bad (void)
  -----------------------

  Returns the unique Bad node current_ir_graph->bad.
  This node is used to express results of dead code elimination.

  ir_node *new_Proj (ir_node *arg, ir_mode *mode, long proj)
  ----------------------------------------------------------

  Selects one entry of a tuple.  This is a hidden `fat edge'.

  Parameters
    *arg      A node producing a tuple.
    *mode     The mode of the value to project.
    proj      The position of the value in the tuple.
  Input:
    The tuple.
  Output:
    The value.

  ir_node *new_Tuple (int arity, ir_node **in)
  --------------------------------------------

  Builds a Tuple from single values.  This is needed to implement
  optimizations that remove a node that produced a tuple.  The node can be
  replaced by the Tuple operation so that the following Proj nodes have not to
  be changed.  (They are hard to find due to the implementation with pointers
  in only one direction.)  The Tuple node is smaller than any other
  node, so that a node can be changed into a Tuple by just changing it's
  opcode and giving it a new in array.

  Parameters
    arity    The number of tuple elements.
    **in     An array containing pointers to the nodes producing the
             tuple elements.

  ir_node *new_Id (ir_node *val, ir_mode *mode)
  ---------------------------------------------

  The single output of the Id operation is it's input.  Also needed
  for optimizations.


  COPING WITH DATA OBJECTS
  ========================

  Two kinds of data objects have to be distinguished for generating
  FIRM.  First there are local variables other than arrays that are
  known to be alias free.  Second there are all other data objects.
  For the first a common SSA representation is built, the second
  are modeled by saving them to memory.  The memory is treated as
  a single local variable, the alias problem is hidden in the
  content of this variable.

  All values known in a Block are listed in the block's attribute,
  block.**graph_arr which is used to automatically insert Phi nodes.
  The following two funcions can be used to add a newly computed value
  to the array, or to get the producer of a value, i.e., the current
  live value.

  inline void set_value (int pos, ir_node *value)
  -----------------------------------------------

  Has to be called for every assignment to a local variable.  It
  adds the value to the array of used values at position pos.  Pos
  has to be a unique identifier for an entry in the procedure's
  definition table.  It can be used to access the value again.

  ir_node *get_value (int pos, ir_mode *mode)
  -------------------------------------------

  Returns the node defining the value referred to by pos. If the
  value is not defined in this block a Phi node is generated and
  all definitions reaching this Phi node are collected.  It can
  happen that the algorithm allocates an unnecessary Phi node,
  e.g. if there is only one definition of this value, but this
  definition reaches the currend block on several different
  paths.  This Phi node will be eliminated if optimizations are
  turned on right after it's creation.


  There are two special routines for the global store:

  inline void set_store (ir_node *store)
  --------------------------------------

  Adds the store to the array of known values at a reserved
  position.

  inline ir_node *get_store (void)
  --------------------------------

  Returns the node defining the actual store.

**/


# ifndef _IRCONS_H_
# define _IRCONS_H_

# include "irgmod.h"
# include "irmode.h"
# include "entity.h"
# include "tv.h"
# include "common.h"
# include "irop.h"
# include "irgraph.h"
# include "type.h"
# include "pdeq.h"
# include "irvrfy.h"

/* irnode constructor                                             */
/* Create a new irnode in irg, with an op, mode, arity and        */
/* some incoming irnodes.                                         */
/* If arity is negative, a node with a dynamic array is created.  */
inline ir_node *new_ir_node (ir_graph *irg, ir_node *block, ir_op *op,
                             ir_mode *mode, int arity, ir_node **in);

/** These headers need not to be here. They are never used by the
    public.
    That's not completely true.  They need not be seen by a frontend,
    but they might be useful for optimizations changing the IR. **/

#if USE_EXPICIT_PHI_IN_STACK
/* A stack needed for the automatic Phi node construction in constructor
   Phi_in. */
typedef struct Phi_in_stack {
  ir_node **stack;
  int       pos;
} Phi_in_stack;
#endif

/* privat interfaces */
/* more detailed construction */

ir_node *new_r_Jmp    (ir_graph *irg, ir_node *block);
ir_node *new_r_Cond   (ir_graph *irg, ir_node *block, ir_node *c);
ir_node *new_r_Return (ir_graph *irg, ir_node *block,
                       ir_node *store, int arity, ir_node **in);
ir_node *new_r_Raise  (ir_graph *irg, ir_node *block,
                       ir_node *store, ir_node *obj);
ir_node *new_r_Const  (ir_graph *irg, ir_node *block,
                       ir_mode *mode, tarval *con);
ir_node *new_r_SymConst (ir_graph *irg, ir_node *block,
                       type_or_id *value, symconst_kind symkind);
ir_node *new_r_Sel    (ir_graph *irg, ir_node *block, ir_node *store,
                       ir_node *objptr, int n_index, ir_node **index,
                       entity *ent);
ir_node *new_r_Call   (ir_graph *irg, ir_node *block, ir_node *store,
                       ir_node *callee, int arity, ir_node **in, type_method *type);
ir_node *new_r_Add    (ir_graph *irg, ir_node *block,
                       ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_r_Sub    (ir_graph *irg, ir_node *block,
                       ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_r_Minus  (ir_graph *irg, ir_node *block,
                       ir_node *op,  ir_mode *mode);
ir_node *new_r_Mul    (ir_graph *irg, ir_node *block,
                       ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_r_Quot   (ir_graph *irg, ir_node *block, ir_node *memop,
                       ir_node *op1, ir_node *op2);
ir_node *new_r_DivMod (ir_graph *irg, ir_node *block,
                       ir_node *memop, ir_node *op1, ir_node *op2);
ir_node *new_r_Div    (ir_graph *irg, ir_node *block, ir_node *memop,
                       ir_node *op1, ir_node *op2);
ir_node *new_r_Mod    (ir_graph *irg, ir_node *block, ir_node *memop,
                       ir_node *op1, ir_node *op2);
ir_node *new_r_Abs    (ir_graph *irg, ir_node *block,
                       ir_node *op, ir_mode *mode);
ir_node *new_r_And    (ir_graph *irg, ir_node *block,
                       ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_r_Or     (ir_graph *irg, ir_node *block,
                       ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_r_Eor    (ir_graph *irg, ir_node *block,
                       ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_r_Not    (ir_graph *irg, ir_node *block,
                       ir_node *op, ir_mode *mode);
ir_node *new_r_Shl    (ir_graph *irg, ir_node *block,
                       ir_node *op, ir_node *k, ir_mode *mode);
ir_node *new_r_Shr    (ir_graph *irg, ir_node *block,
                       ir_node *op, ir_node *k, ir_mode *mode);
ir_node *new_r_Shrs   (ir_graph *irg, ir_node *block,
                       ir_node *op, ir_node *k, ir_mode *mode);
ir_node *new_r_Rot    (ir_graph *irg, ir_node *block,
                       ir_node *op, ir_node *k, ir_mode *mode);
ir_node *new_r_Cmp    (ir_graph *irg, ir_node *block,
                       ir_node *op1, ir_node *op2);
ir_node *new_r_Conv   (ir_graph *irg, ir_node *block,
                       ir_node *op, ir_mode *mode);
ir_node *new_r_Phi    (ir_graph *irg, ir_node *block, int arity,
                       ir_node **in, ir_mode *mode);
ir_node *new_r_Load   (ir_graph *irg, ir_node *block,
                       ir_node *store, ir_node *adr);
ir_node *new_r_Store  (ir_graph *irg, ir_node *block,
                       ir_node *store, ir_node *adr, ir_node *val);
ir_node *new_r_Alloc  (ir_graph *irg, ir_node *block, ir_node *store,
                       ir_node *size, type *alloc_type, where_alloc where);
ir_node *new_r_Free   (ir_graph *irg, ir_node *block, ir_node *store,
                       ir_node *ptr, ir_node *size, type *free_type);
ir_node *new_r_Sync   (ir_graph *irg, ir_node *block, int arity, ir_node **in);
ir_node *new_r_Proj   (ir_graph *irg, ir_node *block, ir_node *arg,
                       ir_mode *mode, long proj);
ir_node *new_r_Tuple  (ir_graph *irg, ir_node *block,
                       int arity, ir_node **in);
ir_node *new_r_Id  (ir_graph *irg, ir_node *block,
                    ir_node *val, ir_mode *mode);
ir_node *new_r_Bad (ir_node *block);



/* public interfaces */
/* normal constructors */

ir_node *new_Block  (void);
ir_node *new_Start  (void);
ir_node *new_End    (void);
ir_node *new_Jmp    (void);
ir_node *new_Cond   (ir_node *c);
ir_node *new_Return (ir_node *store, int arity, ir_node **in);
ir_node *new_Raise  (ir_node *store, ir_node *obj);
ir_node *new_Const  (ir_mode *mode, tarval *con);
ir_node *new_SymConst (type_or_id *value, symconst_kind kind);
ir_node *new_simpleSel (ir_node *store, ir_node *objptr, entity *ent);
ir_node *new_Sel    (ir_node *store, ir_node *objptr, int arity, ir_node **in,
                     entity *ent);
ir_node *new_Call   (ir_node *store, ir_node *callee, int arity, ir_node **in,
                     type_method *type);
ir_node *new_Add    (ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_Sub    (ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_Minus  (ir_node *op,  ir_mode *mode);
ir_node *new_Mul    (ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_Quot   (ir_node *memop, ir_node *op1, ir_node *op2);
ir_node *new_DivMod (ir_node *memop, ir_node *op1, ir_node *op2);
ir_node *new_Div    (ir_node *memop, ir_node *op1, ir_node *op2);
ir_node *new_Mod    (ir_node *memop, ir_node *op1, ir_node *op2);
ir_node *new_Abs    (ir_node *op,                ir_mode *mode);
ir_node *new_And    (ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_Or     (ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_Eor    (ir_node *op1, ir_node *op2, ir_mode *mode);
ir_node *new_Not    (ir_node *op,                ir_mode *mode);
ir_node *new_Shl    (ir_node *op,  ir_node *k,   ir_mode *mode);
ir_node *new_Shr    (ir_node *op,  ir_node *k,   ir_mode *mode);
ir_node *new_Shrs   (ir_node *op,  ir_node *k,   ir_mode *mode);
ir_node *new_Rot    (ir_node *op,  ir_node *k,   ir_mode *mode);
ir_node *new_Cmp    (ir_node *op1, ir_node *op2);
ir_node *new_Conv   (ir_node *op, ir_mode *mode);
ir_node *new_Phi    (int arity, ir_node **in, ir_mode *mode);
ir_node *new_Load   (ir_node *store, ir_node *addr);
ir_node *new_Store  (ir_node *store, ir_node *addr, ir_node *val);
ir_node *new_Alloc  (ir_node *store, ir_node *size, type *alloc_type,
                     where_alloc where);
ir_node *new_Free   (ir_node *store, ir_node *ptr, ir_node *size,
                     type *free_type);
ir_node *new_Sync   (int arity, ir_node **in);
ir_node *new_Proj   (ir_node *arg, ir_mode *mode, long proj);
ir_node *new_Tuple  (int arity, ir_node **in);
ir_node *new_Id     (ir_node *val, ir_mode *mode);
ir_node *new_Bad    (void);


#if USE_EXPICIT_PHI_IN_STACK
Phi_in_stack *new_Phi_in_stack();
#endif

/* initialize ir construction */
void init_cons (void);


# endif /* _IRCONS_H_ */