irnode.c

/*
 * Project:     libFIRM
 * File name:   ir/ir/irnode.c
 * Purpose:     Representation of an intermediate operation.
 * Author:      Martin Trapp, Christian Schaefer
 * Modified by: Goetz Lindenmaier
 * Created:
 * CVS-ID:      $Id$
 * Copyright:   (c) 1998-2003 Universitt Karlsruhe
 * Licence:     This file protected by GPL -  GNU GENERAL PUBLIC LICENSE.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#ifdef HAVE_STRING_H
# include <string.h>
#endif

#include "ident.h"
#include "irnode_t.h"
#include "irgraph_t.h"
#include "irmode_t.h"
#include "typegmod.h"
#include "irbackedge_t.h"
#include "irdump.h"
#include "irop_t.h"
#include "irprog_t.h"
#include "iredges_t.h"

#include "irhooks.h"
#include "irtools.h"

/* some constants fixing the positions of nodes predecessors
   in the in array */
#define CALL_PARAM_OFFSET     2
#define FUNCCALL_PARAM_OFFSET 1
#define SEL_INDEX_OFFSET      2
#define RETURN_RESULT_OFFSET  1  /* mem is not a result */
#define END_KEEPALIVE_OFFSET  0

static const char *pnc_name_arr [] = {
  "pn_Cmp_False", "pn_Cmp_Eq", "pn_Cmp_Lt", "pn_Cmp_Le",
  "pn_Cmp_Gt", "pn_Cmp_Ge", "pn_Cmp_Lg", "pn_Cmp_Leg",
  "pn_Cmp_Uo", "pn_Cmp_Ue", "pn_Cmp_Ul", "pn_Cmp_Ule",
  "pn_Cmp_Ug", "pn_Cmp_Uge", "pn_Cmp_Ne", "pn_Cmp_True"
};

/**
 * returns the pnc name from an pnc constant
 */
const char *get_pnc_string(int pnc) {
  return pnc_name_arr[pnc];
}

/*
 * Calculates the negated (Complement(R)) pnc condition.
 */
int get_negated_pnc(int pnc, ir_mode *mode) {
  pnc ^= pn_Cmp_True;

  /* do NOT add the Uo bit for non-floating point values */
  if (! mode_is_float(mode))
    pnc &= ~pn_Cmp_Uo;

  return pnc;
}

/* Calculates the inversed (R^-1) pnc condition, i.e., "<" --> ">" */
int
get_inversed_pnc(int pnc) {
  int code    = pnc & ~(pn_Cmp_Lt|pn_Cmp_Gt);
  int lesser  = pnc & pn_Cmp_Lt;
  int greater = pnc & pn_Cmp_Gt;

  code |= (lesser ? pn_Cmp_Gt : 0) | (greater ? pn_Cmp_Lt : 0);

  return code;
}

const char *pns_name_arr [] = {
  "initial_exec", "global_store",
  "frame_base", "globals", "args"
};

const char *symconst_name_arr [] = {
  "type_tag", "size", "addr_name", "addr_ent"
};

/**
 * Indicates, whether additional data can be registered to ir nodes.
 * If set to 1, this is not possible anymore.
 */
static int forbid_new_data = 0;

/**
 * The amount of additional space for custom data to be allocated upon
 * creating a new node.
 */
unsigned firm_add_node_size = 0;


/* register new space for every node */
unsigned register_additional_node_data(unsigned size) {
  assert(!forbid_new_data && "Too late to register additional node data");

  if (forbid_new_data)
    return 0;

  return firm_add_node_size += size;
}


void
init_irnode(void) {
	/* Forbid the addition of new data to an ir node. */
	forbid_new_data = 1;
}

/*
 * 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.
 */
ir_node *
new_ir_node (dbg_info *db, ir_graph *irg, ir_node *block, ir_op *op, ir_mode *mode,
         int arity, ir_node **in)
{
  ir_node *res;
  size_t node_size = offsetof(ir_node, attr) + op->attr_size + firm_add_node_size;
  char *p;
  int i, is_bl;

  assert(irg && op && mode);
  p = obstack_alloc (irg->obst, node_size);
  memset(p, 0, node_size);
  res = (ir_node *) (p + firm_add_node_size);

  res->kind     = k_ir_node;
  res->op       = op;
  res->mode     = mode;
  res->visited  = 0;
  res->node_idx = irg_register_node_idx(irg, res);
  res->link     = NULL;
  if (arity < 0) {
    res->in = NEW_ARR_F (ir_node *, 1);  /* 1: space for block */
  } else {
    res->in = NEW_ARR_D (ir_node *, irg->obst, (arity+1));
    memcpy (&res->in[1], in, sizeof (ir_node *) * arity);
  }

  res->in[0] = block;
  set_irn_dbg_info(res, db);
  res->out = NULL;

#ifdef DEBUG_libfirm
  res->node_nr = get_irp_new_node_nr();
#endif

  INIT_LIST_HEAD(&res->edge_info.outs_head);
  is_bl = is_Block(res);
  if (is_bl)
    INIT_LIST_HEAD(&res->attr.block.succ_head);


  for (i = is_bl; i <= arity; ++i)
    edges_notify_edge(res, i - 1, res->in[i], NULL, irg);

  hook_new_node(irg, res);

  return res;
}

/*-- getting some parameters from ir_nodes --*/

int
(is_ir_node)(const void *thing) {
  return _is_ir_node(thing);
}

int
(get_irn_intra_arity)(const ir_node *node) {
  return _get_irn_intra_arity(node);
}

int
(get_irn_inter_arity)(const ir_node *node) {
  return _get_irn_inter_arity(node);
}

int (*_get_irn_arity)(const ir_node *node) = _get_irn_intra_arity;

int
(get_irn_arity)(const ir_node *node) {
  return _get_irn_arity(node);
}

/* Returns the array with ins. This array is shifted with respect to the
   array accessed by get_irn_n: The block operand is at position 0 not -1.
   (@@@ This should be changed.)
   The order of the predecessors in this array is not guaranteed, except that
   lists of operands as predecessors of Block or arguments of a Call are
   consecutive. */
ir_node **
get_irn_in (const ir_node *node) {
  assert(node);
  if (get_interprocedural_view()) { /* handle Filter and Block specially */
    if (get_irn_opcode(node) == iro_Filter) {
      assert(node->attr.filter.in_cg);
      return node->attr.filter.in_cg;
    } else if (get_irn_opcode(node) == iro_Block && node->attr.block.in_cg) {
      return node->attr.block.in_cg;
    }
    /* else fall through */
  }
  return node->in;
}

void
set_irn_in (ir_node *node, int arity, ir_node **in) {
  int i;
  ir_node *** arr;
  ir_graph *irg = current_ir_graph;
  assert(node);
  if (get_interprocedural_view()) { /* handle Filter and Block specially */
    if (get_irn_opcode(node) == iro_Filter) {
      assert(node->attr.filter.in_cg);
      arr = &node->attr.filter.in_cg;
    } else if (get_irn_opcode(node) == iro_Block && node->attr.block.in_cg) {
      arr = &node->attr.block.in_cg;
    } else {
      arr = &node->in;
    }
  } else {
    arr = &node->in;
  }

  for (i = 0; i < arity; i++) {
    if (i < ARR_LEN(*arr)-1)
      edges_notify_edge(node, i, in[i], (*arr)[i+1], irg);
    else
      edges_notify_edge(node, i, in[i], NULL,        irg);
  }
  for(;i < ARR_LEN(*arr)-1; i++) {
    edges_notify_edge(node, i, NULL, (*arr)[i+1], irg);
  }

  if (arity != ARR_LEN(*arr) - 1) {
    ir_node * block = (*arr)[0];
    *arr = NEW_ARR_D(ir_node *, irg->obst, arity + 1);
    (*arr)[0] = block;
  }
  fix_backedges(irg->obst, node);

  memcpy((*arr) + 1, in, sizeof(ir_node *) * arity);
}

ir_node *
(get_irn_intra_n)(const ir_node *node, int n) {
  return _get_irn_intra_n (node, n);
}

ir_node *
(get_irn_inter_n)(const ir_node *node, int n) {
  return _get_irn_inter_n (node, n);
}

ir_node *(*_get_irn_n)(const ir_node *node, int n) = _get_irn_intra_n;

ir_node *
(get_irn_n)(const ir_node *node, int n) {
  return _get_irn_n(node, n);
}

void
set_irn_n (ir_node *node, int n, ir_node *in) {
  assert(node && node->kind == k_ir_node);
  assert(-1 <= n);
  assert(n < get_irn_arity(node));
  assert(in && in->kind == k_ir_node);

  if ((n == -1) && (get_irn_opcode(node) == iro_Filter)) {
    /* Change block pred in both views! */
    node->in[n + 1] = in;
    assert(node->attr.filter.in_cg);
    node->attr.filter.in_cg[n + 1] = in;
    return;
  }
  if (get_interprocedural_view()) { /* handle Filter and Block specially */
    if (get_irn_opcode(node) == iro_Filter) {
      assert(node->attr.filter.in_cg);
      node->attr.filter.in_cg[n + 1] = in;
      return;
    } else if (get_irn_opcode(node) == iro_Block && node->attr.block.in_cg) {
      node->attr.block.in_cg[n + 1] = in;
      return;
    }
    /* else fall through */
  }

  /* Call the hook */
  hook_set_irn_n(node, n, in, node->in[n + 1]);

  /* Here, we rely on src and tgt being in the current ir graph */
  edges_notify_edge(node, n, in, node->in[n + 1], current_ir_graph);

  node->in[n + 1] = in;
}

ir_mode *
(get_irn_mode)(const ir_node *node) {
  return _get_irn_mode(node);
}

void
(set_irn_mode)(ir_node *node, ir_mode *mode)
{
  _set_irn_mode(node, mode);
}

modecode
get_irn_modecode (const ir_node *node)
{
  assert (node);
  return node->mode->code;
}

/** Gets the string representation of the mode .*/
const char *
get_irn_modename (const ir_node *node)
{
  assert(node);
  return get_mode_name(node->mode);
}

ident *
get_irn_modeident (const ir_node *node)
{
  assert(node);
  return get_mode_ident(node->mode);
}

ir_op *
(get_irn_op)(const ir_node *node) {
  return _get_irn_op(node);
}

/* should be private to the library: */
void
(set_irn_op)(ir_node *node, ir_op *op) {
	_set_irn_op(node, op);
}

opcode
(get_irn_opcode)(const ir_node *node)
{
  return _get_irn_opcode(node);
}

const char *
get_irn_opname (const ir_node *node)
{
  assert(node);
  if ((get_irn_op((ir_node *)node) == op_Phi) &&
      (get_irg_phase_state(get_irn_irg((ir_node *)node)) == phase_building) &&
      (get_irn_arity((ir_node *)node) == 0)) return "Phi0";
  return get_id_str(node->op->name);
}

ident *
get_irn_opident (const ir_node *node)
{
  assert(node);
  return node->op->name;
}

unsigned long
(get_irn_visited)(const ir_node *node)
{
  return _get_irn_visited(node);
}

void
(set_irn_visited)(ir_node *node, unsigned long visited)
{
  _set_irn_visited(node, visited);
}

void
(mark_irn_visited)(ir_node *node) {
  _mark_irn_visited(node);
}

int
(irn_not_visited)(const ir_node *node) {
  return _irn_not_visited(node);
}

int
(irn_visited)(const ir_node *node) {
  return _irn_visited(node);
}

void
(set_irn_link)(ir_node *node, void *link) {
  _set_irn_link(node, link);
}

void *
(get_irn_link)(const ir_node *node) {
  return _get_irn_link(node);
}

op_pin_state
(get_irn_pinned)(const ir_node *node) {
  return _get_irn_pinned(node);
}

op_pin_state
(is_irn_pinned_in_irg) (const ir_node *node) {
  return _is_irn_pinned_in_irg(node);
}

void set_irn_pinned(ir_node *node, op_pin_state state) {
  /* due to optimization an opt may be turned into a Tuple */
  if (get_irn_op(node) == op_Tuple)
    return;

  assert(node && get_op_pinned(get_irn_op(node)) >= op_pin_state_exc_pinned);
  assert(state == op_pin_state_pinned || state == op_pin_state_floats);

  node->attr.except.pin_state = state;
}

#ifdef DO_HEAPANALYSIS
/* Access the abstract interpretation information of a node.
   Returns NULL if no such information is available. */
struct abstval *get_irn_abst_value(ir_node *n) {
  return n->av;
}
/* Set the abstract interpretation information of a node. */
void set_irn_abst_value(ir_node *n, struct abstval *os) {
  n->av = os;
}
struct section *firm_get_irn_section(ir_node *n) {
  return n->sec;
}
void firm_set_irn_section(ir_node *n, struct section *s) {
  n->sec = s;
}
#else
/* Dummies needed for firmjni. */
struct abstval *get_irn_abst_value(ir_node *n) { return NULL; }
void set_irn_abst_value(ir_node *n, struct abstval *os) {}
struct section *firm_get_irn_section(ir_node *n) { return NULL; }
void firm_set_irn_section(ir_node *n, struct section *s) {}
#endif /* DO_HEAPANALYSIS */


/* Outputs a unique number for this node */
long get_irn_node_nr(const ir_node *node) {
  assert(node);
#ifdef DEBUG_libfirm
  return node->node_nr;
#else
  return (long)PTR_TO_INT(node);
#endif
}

const_attr
get_irn_const_attr (ir_node *node)
{
  assert (node->op == op_Const);
  return node->attr.con;
}

long
get_irn_proj_attr (ir_node *node)
{
  assert (node->op == op_Proj);
  return node->attr.proj;
}

alloc_attr
get_irn_alloc_attr (ir_node *node)
{
  assert (node->op == op_Alloc);
  return node->attr.a;
}

free_attr
get_irn_free_attr     (ir_node *node)
{
  assert (node->op == op_Free);
  return node->attr.f;
}

symconst_attr
get_irn_symconst_attr (ir_node *node)
{
  assert (node->op == op_SymConst);
  return node->attr.i;
}

ir_type *
get_irn_call_attr (ir_node *node)
{
  assert (node->op == op_Call);
  return node->attr.call.cld_tp = skip_tid(node->attr.call.cld_tp);
}

sel_attr
get_irn_sel_attr (ir_node *node)
{
  assert (node->op == op_Sel);
  return node->attr.s;
}

int
get_irn_phi_attr (ir_node *node)
{
  assert (node->op == op_Phi);
  return node->attr.phi0_pos;
}

block_attr
get_irn_block_attr (ir_node *node)
{
  assert (node->op == op_Block);
  return node->attr.block;
}

load_attr
get_irn_load_attr (ir_node *node)
{
  assert (node->op == op_Load);
  return node->attr.load;
}

store_attr
get_irn_store_attr (ir_node *node)
{
  assert (node->op == op_Store);
  return node->attr.store;
}

except_attr
get_irn_except_attr (ir_node *node)
{
  assert (node->op == op_Div || node->op == op_Quot ||
          node->op == op_DivMod || node->op == op_Mod || node->op == op_Call || node->op == op_Alloc);
  return node->attr.except;
}

void *
get_irn_generic_attr (ir_node *node) {
  return &node->attr;
}

unsigned (get_irn_idx)(const ir_node *node) {
  assert(is_ir_node(node));
  return _get_irn_idx(node);
}

int get_irn_pred_pos(ir_node *node, ir_node *arg) {
  int i;
  for (i = get_irn_arity(node) - 1; i >= 0; i--) {
    if (get_irn_n(node, i) == arg)
      return i;
  }
  return -1;
}

/** manipulate fields of individual nodes **/

/* this works for all except Block */
ir_node *
get_nodes_block (const ir_node *node) {
  assert (!(node->op == op_Block));
	assert (is_irn_pinned_in_irg(node) && "block info may be incorrect");
  return get_irn_n(node, -1);
}

void
set_nodes_block (ir_node *node, ir_node *block) {
  assert (!(node->op == op_Block));
  set_irn_n(node, -1, block);
}

/* Test whether arbitrary node is frame pointer, i.e. Proj(pn_Start_P_frame_base)
 * from Start.  If so returns frame type, else Null. */
ir_type *is_frame_pointer(ir_node *n) {
  if (is_Proj(n) && (get_Proj_proj(n) == pn_Start_P_frame_base)) {
    ir_node *start = get_Proj_pred(n);
    if (get_irn_op(start) == op_Start) {
      return get_irg_frame_type(get_irn_irg(start));
    }
  }
  return NULL;
}

/* Test whether arbitrary node is globals pointer, i.e. Proj(pn_Start_P_globals)
 * from Start.  If so returns global type, else Null. */
ir_type *is_globals_pointer(ir_node *n) {
  if (is_Proj(n) && (get_Proj_proj(n) == pn_Start_P_globals)) {
    ir_node *start = get_Proj_pred(n);
    if (get_irn_op(start) == op_Start) {
      return get_glob_type();
    }
  }
  return NULL;
}

/* Test whether arbitrary node is tls pointer, i.e. Proj(pn_Start_P_tls)
 * from Start.  If so returns tls type, else Null. */
ir_type *is_tls_pointer(ir_node *n) {
  if (is_Proj(n) && (get_Proj_proj(n) == pn_Start_P_globals)) {
      ir_node *start = get_Proj_pred(n);
      if (get_irn_op(start) == op_Start) {
        return get_tls_type();
      }
  }
  return NULL;
}

/* Test whether arbitrary node is value arg base, i.e. Proj(pn_Start_P_value_arg_base)
 * from Start.  If so returns 1, else 0. */
int is_value_arg_pointer(ir_node *n) {
  if ((get_irn_op(n) == op_Proj) &&
      (get_Proj_proj(n) == pn_Start_P_value_arg_base) &&
      (get_irn_op(get_Proj_pred(n)) == op_Start))
    return 1;
  return 0;
}

/* Returns an array with the predecessors of the Block. Depending on
   the implementation of the graph data structure this can be a copy of
   the internal representation of predecessors as well as the internal
   array itself. Therefore writing to this array might obstruct the ir. */
ir_node **
get_Block_cfgpred_arr (ir_node *node)
{
  assert ((node->op == op_Block));
  return (ir_node **)&(get_irn_in(node)[1]);
}

int
(get_Block_n_cfgpreds)(ir_node *node) {
  return _get_Block_n_cfgpreds(node);
}

ir_node *
(get_Block_cfgpred)(ir_node *node, int pos) {
  return _get_Block_cfgpred(node, pos);
}

void
set_Block_cfgpred (ir_node *node, int pos, ir_node *pred) {
  assert (node->op == op_Block);
  set_irn_n(node, pos, pred);
}

ir_node  *
(get_Block_cfgpred_block)(ir_node *node, int pos) {
  return _get_Block_cfgpred_block(node, pos);
}

int
get_Block_matured (ir_node *node) {
  assert (node->op == op_Block);
  return (int)node->attr.block.matured;
}

void
set_Block_matured (ir_node *node, int matured) {
  assert (node->op == op_Block);
  node->attr.block.matured = matured;
}

unsigned long
(get_Block_block_visited)(ir_node *node) {
  return _get_Block_block_visited(node);
}

void
(set_Block_block_visited)(ir_node *node, unsigned long visit) {
  _set_Block_block_visited(node, visit);
}

/* For this current_ir_graph must be set. */
void
(mark_Block_block_visited)(ir_node *node) {
  _mark_Block_block_visited(node);
}

int
(Block_not_block_visited)(ir_node *node) {
  return _Block_not_block_visited(node);
}

ir_node *
get_Block_graph_arr (ir_node *node, int pos) {
  assert (node->op == op_Block);
  return node->attr.block.graph_arr[pos+1];
}

void
set_Block_graph_arr (ir_node *node, int pos, ir_node *value) {
  assert (node->op == op_Block);
  node->attr.block.graph_arr[pos+1] = value;
}

void set_Block_cg_cfgpred_arr(ir_node * node, int arity, ir_node ** in) {
  assert(node->op == op_Block);
  if (node->attr.block.in_cg == NULL || arity != ARR_LEN(node->attr.block.in_cg) - 1) {
    node->attr.block.in_cg = NEW_ARR_D(ir_node *, current_ir_graph->obst, arity + 1);
    node->attr.block.in_cg[0] = NULL;
    node->attr.block.cg_backedge = new_backedge_arr(current_ir_graph->obst, arity);
    {
      /* Fix backedge array.  fix_backedges() operates depending on
     interprocedural_view. */
      int ipv = get_interprocedural_view();
      set_interprocedural_view(1);
      fix_backedges(current_ir_graph->obst, node);
      set_interprocedural_view(ipv);
    }
  }
  memcpy(node->attr.block.in_cg + 1, in, sizeof(ir_node *) * arity);
}

void set_Block_cg_cfgpred(ir_node * node, int pos, ir_node * pred) {
  assert(node->op == op_Block &&
     node->attr.block.in_cg &&
     0 <= pos && pos < ARR_LEN(node->attr.block.in_cg) - 1);
  node->attr.block.in_cg[pos + 1] = pred;
}

ir_node ** get_Block_cg_cfgpred_arr(ir_node * node) {
  assert(node->op == op_Block);
  return node->attr.block.in_cg == NULL ? NULL : node->attr.block.in_cg  + 1;
}

int get_Block_cg_n_cfgpreds(ir_node * node) {
  assert(node->op == op_Block);
  return node->attr.block.in_cg == NULL ? 0 : ARR_LEN(node->attr.block.in_cg) - 1;
}

ir_node * get_Block_cg_cfgpred(ir_node * node, int pos) {
  assert(node->op == op_Block && node->attr.block.in_cg);
  return node->attr.block.in_cg[pos + 1];
}

void remove_Block_cg_cfgpred_arr(ir_node * node) {
  assert(node->op == op_Block);
  node->attr.block.in_cg = NULL;
}

ir_node *(set_Block_dead)(ir_node *block) {
  return _set_Block_dead(block);
}

int (is_Block_dead)(const ir_node *block) {
  return _is_Block_dead(block);
}

ir_extblk *get_Block_extbb(const ir_node *block) {
	ir_extblk *res;
  assert(is_Block(block));
	res = block->attr.block.extblk;
	assert(res == NULL || is_ir_extbb(res));
  return res;
}

void set_Block_extbb(ir_node *block, ir_extblk *extblk) {
  assert(is_Block(block));
	assert(extblk == NULL || is_ir_extbb(extblk));
  block->attr.block.extblk = extblk;
}

int
get_End_n_keepalives(ir_node *end) {
  assert (end->op == op_End);
  return (get_irn_arity(end) - END_KEEPALIVE_OFFSET);
}

ir_node *
get_End_keepalive(ir_node *end, int pos) {
  assert (end->op == op_End);
  return get_irn_n(end, pos + END_KEEPALIVE_OFFSET);
}

void
add_End_keepalive (ir_node *end, ir_node *ka) {
  int l;
  ir_graph *irg = get_irn_irg(end);

  assert(end->op == op_End);
  l = ARR_LEN(end->in);
  ARR_APP1(ir_node *, end->in, ka);
  edges_notify_edge(end, l - 1, end->in[l], NULL, irg);
}

void
set_End_keepalive(ir_node *end, int pos, ir_node *ka) {
  assert (end->op == op_End);
  set_irn_n(end, pos + END_KEEPALIVE_OFFSET, ka);
}

/* Set new keep-alives */
void set_End_keepalives(ir_node *end, int n, ir_node *in[]) {
  int i;
  ir_graph *irg = get_irn_irg(end);

  /* notify that edges are deleted */
  for (i = 1 + END_KEEPALIVE_OFFSET; i < ARR_LEN(end->in); ++i) {
    edges_notify_edge(end, i, end->in[i], NULL, irg);
  }
  ARR_RESIZE(ir_node *, end->in, n + 1 + END_KEEPALIVE_OFFSET);

  for (i = 0; i < n; ++i) {
    end->in[1 + END_KEEPALIVE_OFFSET + i] = in[i];
    edges_notify_edge(end, END_KEEPALIVE_OFFSET + i, NULL, end->in[1 + END_KEEPALIVE_OFFSET + i], irg);
  }
}

void
free_End (ir_node *end) {
  assert (end->op == op_End);
  end->kind = k_BAD;
  DEL_ARR_F(end->in);
  end->in = NULL;   /* @@@ make sure we get an error if we use the
               in array afterwards ... */
}

/* Return the target address of an IJmp */
ir_node *get_IJmp_target(ir_node *ijmp) {
  assert(ijmp->op == op_IJmp);
  return get_irn_n(ijmp, 0);
}

/** Sets the target address of an IJmp */
void set_IJmp_target(ir_node *ijmp, ir_node *tgt) {
  assert(ijmp->op == op_IJmp);
  set_irn_n(ijmp, 0, tgt);
}

/*
> Implementing the case construct (which is where the constant Proj node is
> important) involves far more than simply determining the constant values.
> We could argue that this is more properly a function of the translator from
> Firm to the target machine.  That could be done if there was some way of
> projecting "default" out of the Cond node.
I know it's complicated.
Basically there are two proglems:
 - determining the gaps between the projs
 - determining the biggest case constant to know the proj number for
   the default node.
I see several solutions:
1. Introduce a ProjDefault node.  Solves both problems.
   This means to extend all optimizations executed during construction.
2. Give the Cond node for switch two flavors:
   a) there are no gaps in the projs  (existing flavor)
   b) gaps may exist, default proj is still the Proj with the largest
      projection number.  This covers also the gaps.
3. Fix the semantic of the Cond to that of 2b)

Solution 2 seems to be the best:
Computing the gaps in the Firm representation is not too hard, i.e.,
libFIRM can implement a routine that transforms between the two
flavours.  This is also possible for 1) but 2) does not require to
change any existing optimization.
Further it should be far simpler to determine the biggest constant than
to compute all gaps.
I don't want to choose 3) as 2a) seems to have advantages for
dataflow analysis and 3) does not allow to convert the representation to
2a).
*/
ir_node *
get_Cond_selector (ir_node *node) {
  assert (node->op == op_Cond);
  return get_irn_n(node, 0);
}

void
set_Cond_selector (ir_node *node, ir_node *selector) {
  assert (node->op == op_Cond);
  set_irn_n(node, 0, selector);
}

cond_kind
get_Cond_kind (ir_node *node) {
  assert (node->op == op_Cond);
  return node->attr.c.kind;
}

void
set_Cond_kind (ir_node *node, cond_kind kind) {
  assert (node->op == op_Cond);
  node->attr.c.kind = kind;
}

long
get_Cond_defaultProj (ir_node *node) {
  assert (node->op == op_Cond);
  return node->attr.c.default_proj;
}

ir_node *
get_Return_mem (ir_node *node) {
  assert (node->op == op_Return);
  return get_irn_n(node, 0);
}

void
set_Return_mem (ir_node *node, ir_node *mem) {
  assert (node->op == op_Return);
  set_irn_n(node, 0, mem);
}

int
get_Return_n_ress (ir_node *node) {
  assert (node->op == op_Return);
  return (get_irn_arity(node) - RETURN_RESULT_OFFSET);
}

ir_node **
get_Return_res_arr (ir_node *node)
{
  assert ((node->op == op_Return));
  if (get_Return_n_ress(node) > 0)
    return (ir_node **)&(get_irn_in(node)[1 + RETURN_RESULT_OFFSET]);
  else
    return NULL;
}

/*
void
set_Return_n_res (ir_node *node, int results) {
  assert (node->op == op_Return);
}
*/

ir_node *
get_Return_res (ir_node *node, int pos) {
  assert (node->op == op_Return);
  assert (get_Return_n_ress(node) > pos);
  return get_irn_n(node, pos + RETURN_RESULT_OFFSET);
}