struct / union in initializer, RFE #901.

[sdcc.git] / sdcc / src / SDCCgenconstprop.cc

// (c) 2023-2024 Philipp Klaus Krause, philipp@colecovision.eu
//
// SPDX-License-Identifier: GPL-2.0-or-later
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option) any
// later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
//
// Generalized constant propagation.

#undef DEBUG_GCP_ANALYSIS
#undef DEBUG_GCP_OPT

#include <map>
#include <set>
#include <queue>
#include <iostream>
#include <ios>

#include <boost/graph/graphviz.hpp>

#include "SDCCtree_dec.hpp" // We just need it for the titlewriter for debug cfg dumping.

extern "C"
{
#include "common.h"
}

static bool
operator != (const valinfo &v0, const valinfo &v1)
{
  if (v0.nothing && v1.nothing)
    return (true);
  return (v0.nothing != v1.nothing || v0.anything != v1.anything ||
    v0.min != v1.min || v0.max != v1.max ||
    v0.knownbitsmask != v1.knownbitsmask);
}

struct valinfos
{
  std::map <int, struct valinfo> map;
};

struct cfg_genconstprop_node
{
  iCode *ic;
};

typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS, cfg_genconstprop_node, struct valinfos> cfg_t;

// A quick-and-dirty function to get the CFG from sdcc (a simplified version of the function from SDCCralloc.hpp).
static void
create_cfg_genconstprop (cfg_t &cfg, iCode *start_ic, ebbIndex *ebbi)
{
  iCode *ic;

  std::map<int, unsigned int> key_to_index;
  {
    int i;

    for (ic = start_ic, i = 0; ic; ic = ic->next, i++)
      {
        boost::add_vertex(cfg);
        key_to_index[ic->key] = i;
        cfg[i].ic = ic;
      }
  }

  // Get control flow graph from sdcc.
  for (ic = start_ic; ic; ic = ic->next)
    {
      if (ic->op != GOTO && ic->op != RETURN && ic->op != JUMPTABLE && ic->next)
        boost::add_edge(key_to_index[ic->key], key_to_index[ic->next->key], cfg);

      if (ic->op == GOTO)
        boost::add_edge(key_to_index[ic->key], key_to_index[eBBWithEntryLabel(ebbi, ic->label)->sch->key], cfg);
      else if (ic->op == RETURN)
        boost::add_edge(key_to_index[ic->key], key_to_index[eBBWithEntryLabel(ebbi, returnLabel)->sch->key], cfg);
      else if (ic->op == IFX)
        boost::add_edge(key_to_index[ic->key], key_to_index[eBBWithEntryLabel(ebbi, IC_TRUE(ic) ? IC_TRUE(ic) : IC_FALSE(ic))->sch->key], cfg);
      else if (ic->op == JUMPTABLE) // This can create a multigraph. We actually need those multiple edges later for correctness of the analysis.
        for (symbol *lbl = (symbol *)(setFirstItem (IC_JTLABELS (ic))); lbl; lbl = (symbol *)(setNextItem (IC_JTLABELS (ic))))
          boost::add_edge(key_to_index[ic->key], key_to_index[eBBWithEntryLabel(ebbi, lbl)->sch->key], cfg);
    }
}

struct valinfo
getTypeValinfo (sym_link *type, bool loose)
{
  struct valinfo v;
  v.anything = true;
  v.nothing = false;
  // Initialize all members of v, to ensure we don't read uninitalized memory later.
  v.min = v.max = 0ll;
  v.knownbitsmask = 0ull;
  v.knownbits = 0ull;

  if (IS_BOOLEAN (type))
    {
      v.anything = false;
      v.min = 0;
      v.max = 1;
      v.knownbitsmask = ~1ull;
      v.knownbits = 0;
    }
  else if (IS_PTR (type) || IS_ARRAY (type))
    {
      v.anything = false;
      v.min = 0;
      if (IS_FUNCPTR (type))
        v.max = (1ll << ((IFFUNC_ISBANKEDCALL (type->next) ? BFUNCPTRSIZE : FUNCPTRSIZE) * 8)) - 1;
      else
        v.max = (1ll << (GPTRSIZE * 8)) - 1;
      v.knownbitsmask = ~((unsigned long long)v.max);
      if (TARGET_IS_MCS51 && IS_PTR (type) && !IS_GENPTR (type) ||
        TARGET_PDK_LIKE && IS_PTR (type) && (DCL_TYPE (type) == CPOINTER || DCL_TYPE (type) == POINTER))
        {
          int addrbits = GPTRSIZE * 8;
          if (TARGET_IS_MCS51)
            {
              if (DCL_TYPE (type) == POINTER)
                addrbits = 7;
              else if (DCL_TYPE (type) == IPOINTER || DCL_TYPE (type) == PPOINTER)
                addrbits = 8;
              else
                addrbits = 16;
            }
          else if (TARGET_PDK_LIKE)
            addrbits = (DCL_TYPE (type) == CPOINTER ? 10 : 6) + TARGET_IS_PDK14 * 1 + TARGET_IS_PDK15 * 2 + TARGET_IS_PDK16 * 3;
          else
            wassert (0);
          unsigned long long addrmask = ~(~0ull << addrbits);
          v.knownbitsmask |= ~addrmask;
          v.knownbits &= addrmask;
          if (TARGET_IS_MCS51)
            v.knownbits |= (unsigned long long)pointerTypeToGPByte (DCL_TYPE (type), 0, 0) << 16;
          else if (TARGET_PDK_LIKE)
            v.knownbits |= (DCL_TYPE (type) == CPOINTER ? 0x8000 : 0x0000);
          else
            wassert (0);
        }
    }
  else if (IS_INTEGRAL (type) && IS_UNSIGNED (type) && bitsForType (type) < 64)
    {
      v.anything = false;
      v.min = 0;
      v.max = 0xffffffffffffffffull >> (64 - bitsForType (type));
      v.knownbitsmask = ~(0xffffffffffffffffull >> (64 - bitsForType (type)));
      v.knownbits = 0;
    }
  else if (IS_INTEGRAL (type) && !IS_UNSIGNED (type) && bitsForType (type) < 63)
    {
      v.anything = false;
      v.max = 0x7fffffffffffffffull >> (64 - bitsForType (type));
      v.min = -v.max - 1;
      if (loose && IS_CHAR (type))
        v.max = 0xffffffffffffffffull >> (64 - bitsForType (type)); // Use upper limit of unsigned type here, since sometimes, SDCC generates incorrect AST (using signed char, where there should be unsigned char) trying to avoid the costs of integer promotion.
      v.knownbitsmask = ~(0xffffffffffffffffull >> (64 - bitsForType (type)));
      v.knownbits = 0;
    }
  return (v);
}

static void
valinfoCast (struct valinfo *result, sym_link *targettype, const struct valinfo &right);

struct valinfo
getOperandValinfo (const iCode *ic, const operand *op)
{
  wassert (ic);

  struct valinfo v;
  v.anything = true;
  v.nothing = false;
  v.min = v.max = 0;
  v.knownbitsmask = 0ull;
  v.knownbits = 0ull;

  if (!op)
    return (v);

  sym_link *type = operandType (op);

  if (IS_INTEGRAL (type) && bitsForType (type) < 64 && !IS_OP_VOLATILE (op) && // Todo: More exact check than this bits thing?
    (IS_OP_LITERAL (op) || IS_SYMOP (op) && SPEC_CONST (type) && OP_SYMBOL_CONST (op)->ival && IS_AST_VALUE (list2expr (OP_SYMBOL_CONST (op)->ival))))
    {
      struct valinfo v2;
      long long litval;
      if (IS_OP_LITERAL (op))
        litval = operandLitValueUll (op);
      else
        litval = ullFromVal (list2expr (OP_SYMBOL_CONST (op)->ival)->opval.val);
      v2.anything = false;
      v2.nothing = false;
      v2.min = litval;
      v2.max = litval;
      v2.knownbitsmask = ~0ull;
      v2.knownbits = litval;
      valinfoCast (&v, type, v2); // Need to cast: ival could be out of range of type.
      return (v);
    }
  else if (IS_ITEMP (op) && !IS_OP_VOLATILE (op))
    {
      if (ic->valinfos && ic->valinfos->map.find (op->key) != ic->valinfos->map.end ())
        return (ic->valinfos->map[op->key]);
      v.nothing = true;
      v.anything = false;
      return (v);
    }
  else
    return (getTypeValinfo (type, true));
}

bool
valinfo_union (struct valinfo *v0, const struct valinfo v1)
{
  bool change = false;
  auto new_anything = v0->anything || v1.anything;
  change |= (v0->anything != new_anything);
  v0->anything = new_anything;
  auto new_nothing = v0->nothing && v1.nothing;
  change |= (v0->nothing != new_nothing);
  v0->nothing = new_nothing;
  auto new_min = std::min (v0->min, v1.min);
  change |= (v0->min != new_min);
  v0->min = new_min;
  auto new_max = std::max (v0->max, v1.max);
  change |= (v0->max != new_max);
  v0->max = new_max;
  auto new_knownbitsmask = v0->knownbitsmask & v1.knownbitsmask & ~(v0->knownbits ^ v1.knownbits);
  change |= (v0->knownbitsmask != new_knownbitsmask);
  v0->knownbitsmask = new_knownbitsmask;
  return (change);
}

bool
valinfos_union (iCode *ic, int key, const struct valinfo &v)
{
  if (!ic /*|| !bitVectBitValue(ic->rlive, key)*/) // Unfortunately, rlive info is inaccurate, so we can't rely on it.
    return (false);

  if (ic->valinfos && ic->valinfos->map.find (key) != ic->valinfos->map.end())
    return (valinfo_union (&ic->valinfos->map[key], v));
  else
    {
      if (!ic->valinfos)
        ic->valinfos = new struct valinfos;
      ic->valinfos->map[key] = v;
      return (true);
    }
}

bool
valinfos_unions (iCode *ic, const struct valinfos &v)
{
  bool change = false;
  for (auto i = v.map.begin(); i != v.map.end(); ++i)
    change |= valinfos_union (ic, i->first, i->second);
  return (change);
}

static void
dump_op_info (std::ostream &os, const iCode *ic, operand *op)
{
  struct valinfo v = getOperandValinfo (ic, op);
  os << "";
  if (v.nothing)
    os << "X";
  if (v.anything)
    os << "*";
  else
    os << "[" << v.min << ", " << v.max << "] " << v.knownbitsmask;
}

// Dump cfg.
static void
dump_cfg_genconstprop (const cfg_t &cfg, const std::string& suffix)
{
  std::ofstream dump_file ((std::string (dstFileName) + ".dumpgenconstpropcfg" + suffix + (currFunc ? currFunc->rname : "__global") + ".dot").c_str());

  std::string *name = new std::string[num_vertices (cfg)];
  for (unsigned int i = 0; i < boost::num_vertices (cfg); i++)
    {
      std::ostringstream os;
      iCode *ic = cfg[i].ic;
      os << i << ", " << ic->key << ": (";
      os << std::showbase << std::hex;
      if (ic->left)
        dump_op_info (os, ic, IC_LEFT (ic));
      os << ", ";
      if (ic->right)
        dump_op_info (os, ic, IC_RIGHT (ic));
      os << ")";
      if (ic->resultvalinfo)
        {
          os << " -> ";
          if (ic->resultvalinfo->nothing)
            os << "X";
          else if (ic->resultvalinfo->anything)
            os << "*";
          else
            os << "[" << ic->resultvalinfo->min << ", " << ic->resultvalinfo->max << "] " << ic->resultvalinfo->knownbitsmask;
        }
      name[i] = os.str();
    }
  boost::write_graphviz(dump_file, cfg, boost::make_label_writer(name), boost::default_writer(), cfg_titlewriter((currFunc ? currFunc->rname : "__global"), " generalized constant propagation"));

  delete[] name;
}

// Update fields of valinfo struct from each other. TODO: Make some of this work also for negative v->min.
static void
valinfoUpdate (struct valinfo *v)
{
  if (v->anything || v->nothing)
    return;

  // Update bits from min/max.
  if (v->min == v->max) // Fixed value.
    {
      v->knownbitsmask = ~0ull;
      v->knownbits = v->min;
      return;
    }
  for (int i = 0; i < 62; i++) // Leading zeroes.
    {
      if (v->min >= 0 && v->max < (1ll << i))
        {
          v->knownbitsmask |= (~0ull << i);
          v->knownbits &= ~(~0ull << i);
        }
    }

  // Update min/max from bits.
  if (v->min >= 0)
    {
      unsigned long long bitmax = (v->knownbitsmask & v->knownbits) | ~v->knownbitsmask;
      if (bitmax < (unsigned long long)(v->max))
        v->max = bitmax;
      unsigned long long bitmin = v->knownbitsmask & v->knownbits;
      if (bitmin > (unsigned long long)(v->min))
        v->min = bitmin;
    }
}

static void
valinfoPlus (struct valinfo *result, sym_link *resulttype, const struct valinfo &left, const struct valinfo &right)
{
  if (result->anything)
    result->knownbitsmask = 0ull;
  // todo: rewrite using ckd_add when we can assume host compiler has c2x support!
  if (!left.anything && !right.anything &&
    left.min > LLONG_MIN / 2 && right.min > LLONG_MIN / 2 &&
    left.max < LLONG_MAX / 2 && right.max < LLONG_MAX / 2)
    {
      result->nothing = left.nothing || right.nothing;
      auto min = left.min + right.min;
      auto max = left.max + right.max;
      if (result->anything || min >= result->min && max <= result->max)
        {
          result->anything = false;
          result->min = min;
          result->max = max;
        }
    }
  if (IS_PTR (resulttype) && !left.anything && !right.anything)
    {
      if (TARGET_IS_MCS51)
        {
          result->knownbitsmask |= (left.knownbitsmask & 0xff0000ull);
          result->knownbits = result->knownbits & ~0xff0000ull | left.knownbits & 0xff0000ull;
        }
      else if (TARGET_PDK_LIKE)
        {
          result->knownbitsmask |= (left.knownbitsmask & 0x8000ull);
          result->knownbits = result->knownbits & ~0x8000ull | left.knownbits & 0x8000ull;
        }
    }
  if (!left.anything && !right.anything &&
    left.min >= 0 && right.min >= 0)
    {
      for (int i = 0; i < 61; i++) // If there are 0 bits in the same position on both sides, carry will be absorbed and not affect the following bit.
        {
          unsigned long long mask = (0x3ull << i);
          if ((left.knownbitsmask & mask) != mask)
            continue;
          if ((right.knownbitsmask & mask) != mask)
            continue;
          unsigned long long mask1 = (0x1ull << i);
          if ((left.knownbits & mask1) || (right.knownbits & mask1))
            continue;
          unsigned long long mask2 = (0x2ull << i);
          if ((left.knownbits & mask2) && (right.knownbits & mask2))
            continue;
          result->knownbitsmask |= mask2;
          if ((left.knownbits & mask2) || (right.knownbits & mask2))
            result->knownbits |= mask2; 
          else
            result->knownbits &= ~mask2; 
        }
    }
}

static void
valinfoMinus (struct valinfo *result, sym_link *resulttype, const struct valinfo &left, const struct valinfo &right)
{
  if (result->anything)
    result->knownbitsmask = 0ull;

  if (IS_PTR (resulttype) && !left.anything && !right.anything)
    {
      if (TARGET_IS_MCS51)
        {
          result->knownbitsmask |= (left.knownbitsmask & 0xff0000ull);
          result->knownbits = result->knownbits & ~0xff0000ull | left.knownbits & 0xff0000ull;
        }
      else if (TARGET_PDK_LIKE)
        {
          result->knownbitsmask |= (left.knownbitsmask & 0x8000ull);
          result->knownbits = result->knownbits & ~0x8000ull | left.knownbits & 0x8000ull;
        }
    }
  // todo: rewrite using ckd_sub when we can assume host compiler has c2x support!
  if (!left.anything && !right.anything &&
    left.min > LLONG_MIN / 2 && right.min > LLONG_MIN / 2 &&
    left.max < LLONG_MAX / 2 && right.max < LLONG_MAX / 2)
    {
      result->nothing = left.nothing || right.nothing;
      auto min = left.min - right.max;
      auto max = left.max - right.min;
      if (result->anything || min >= result->min && max <= result->max)
        {
          result->anything = false;
          result->min = min;
          result->max = max;
        }
    }
}

static void
valinfoMult (struct valinfo *result, const struct valinfo &left, const struct valinfo &right)
{
  if (result->anything)
    result->knownbitsmask = 0ull;

  // todo: rewrite using ckd_mul when we can assume host compiler has c2x support!
  if (!left.anything && !right.anything &&
    left.min >=0 && right.min >= 0 &&
    left.max < (1ll << 31) && right.max < (1ll << 31))
    {
      result->nothing = left.nothing || right.nothing;
      auto min = left.min * right.min;
      auto max = left.max * right.max;
      if (result->anything || min >= result->min && max <= result->max)
        {
          result->anything = false;
          result->min = min;
          result->max = max;
        }
    }
}

static void
valinfoDiv (struct valinfo *result, const struct valinfo &left, const struct valinfo &right)
{
  if (result->anything)
    result->knownbitsmask = 0ull;

  if (!left.anything && left.min >= result->min && left.max <= result->max)
    {
      if (!right.anything && right.min >= 0)
        {
          result->min = std::min (left.min, 0ll);
          result->max = std::max (left.max, 0ll);
        }
    }
  if (!right.anything && right.min > 0 && result->max >= 0)
    result->max /= right.min;
}

static void
valinfoMod (struct valinfo *result, const struct valinfo &left, const struct valinfo &right)
{
  if (result->anything)
    result->knownbitsmask = 0ull;

  if (!left.anything && left.min >= result->min && left.max <= result->max)
    {
      result->min = std::min (left.min, 0ll);
      result->max = std::max (left.max, 0ll);
    }
  if (!left.anything && !right.anything && left.min >= 0 && right.min >= 0 && right.max <= result->max)
    result->max = right.max - 1;
}

static void
valinfoOr (struct valinfo *result, const struct valinfo &left, const struct valinfo &right)
{
  if (!left.anything && !right.anything &&
    left.min >= 0 && right.min >= 0 && !result->anything)
    {
      result->nothing = left.nothing || right.nothing;
      result->min = std::max (left.min, right.min);
      result->max = std::max (left.max, right.max);
      long long max = std::min (left.max, right.max);
      for(int i = 0; max > 0; i++)
        {
          result->max |= (1ll << i);
          max >>= 1;
        } 
    }
  result->knownbitsmask = (left.knownbitsmask & right.knownbitsmask) | (left.knownbitsmask & left.knownbits) | (right.knownbitsmask & right.knownbits);
  result->knownbits = left.knownbits | right.knownbits;
}

static void
valinfoAnd (struct valinfo *result, sym_link *resulttype, const struct valinfo &left_orig, const struct valinfo &right_orig)
{
  // In iCode, bitwise and sometimes has operands of different type.
  struct valinfo left, right;
  valinfoCast (&left, resulttype, left_orig);
  valinfoCast (&right, resulttype, right_orig);

  if (!left.anything && !right.anything &&
    (left.min >= 0 || right.min >= 0))
    {
      result->anything = false;
      result->nothing = left.nothing || right.nothing;
      result->min = 0;
      if (left.min >= 0 && right.min >= 0)
        result->max = std::min (left.max, right.max);
    }
  result->knownbitsmask = (left.knownbitsmask & right.knownbitsmask) | (left.knownbitsmask & ~left.knownbits) | (right.knownbitsmask & ~right.knownbits);
  result->knownbits = left.knownbits & right.knownbits;
}

static void
valinfoXor (struct valinfo *result, const struct valinfo &left, const struct valinfo &right)
{
  if (!left.anything && !right.anything &&
    left.min >= 0 && right.min >= 0 && !result->anything)
    {
      result->nothing = left.nothing || right.nothing;
      result->min = 0;
      result->max = std::max (left.max, right.max);
      long long max = std::min (left.max, right.max);
      for(int i = 0; max > 0; i++)
        {
          result->max |= (1ll << i);
          max >>= 1;
        } 
    }
  result->knownbitsmask = (left.knownbitsmask & right.knownbitsmask);
  result->knownbits = left.knownbits ^ right.knownbits;
}

static void
valinfoGetABit (struct valinfo *result, const struct valinfo &left, const struct valinfo &right)
{
  result->anything = false;
  result->nothing = left.nothing || right.nothing;
  if (result->max > 0)
    {
      result->min = 0;
      result->max = 1;
    }
  result->knownbitsmask = ~1ull;
}

static void
valinfoLeft (struct valinfo *result, const struct valinfo &left, const struct valinfo &right)
{
  if (!left.anything && !right.anything && right.min == right.max && right.max < 62)
    {
      result->nothing = left.nothing || right.nothing;
      long long min, max;
      min = left.min;
      max = left.max;
      for(long long r = right.max; r; r--)
        {
          if (min < 0 || max > (1ll << 61))
            return;
          min <<= 1;
          max <<= 1;
        }
      if (!result->anything)
        max = std::min (result->max, max);
      result->anything = false;
      result->min = min;
      result->max = max;
    }
  if(!right.anything && right.min > 0 && right.min < 63)
    {
      result->knownbitsmask |= ~(~0ull << right.min);
      result->knownbits &= (~0ull << right.min);
    }
}

static void
valinfoRight (struct valinfo *result, const struct valinfo &left, const struct valinfo &right)
{
  if (!left.anything && !right.anything &&
    left.min >= 0 && right.min >= 0 && right.min <= 61)
    {
      result->nothing = left.nothing || right.nothing;
      result->min = 0;
      auto max = (left.max >> right.min);
      if (result->anything || max <= result->max)
        result->max = max;
      result->anything = false;
      if (right.min == right.max)
        {
          result->knownbitsmask = left.knownbitsmask >> right.min;
          result->knownbits = left.knownbits >> right.min;
        }
    }
}

static void
valinfoCast (struct valinfo *result, sym_link *targettype, const struct valinfo &right)
{
  *result = getTypeValinfo (targettype, false);
  if (right.nothing)
    result->nothing = true;
  else if (!right.anything && (IS_INTEGRAL (targettype) || IS_GENPTR (targettype)) && 
    (!result->anything && right.min >= result->min && right.max <= result->max || result->anything))
    {
      result->min = right.min;
      result->max = right.max;
      if (result->min >= 0)
        {
          result->knownbitsmask = right.knownbitsmask;
          result->knownbits = right.knownbits;
        }
      else if (result->max < 0 && bitsForType (targettype) < 64)
        {
          unsigned long long topmask = (~0ull << bitsForType (targettype));
          result->knownbitsmask = right.knownbitsmask | topmask;
          result->knownbits = right.knownbits | topmask;
        }
    }
  else if (!right.anything && IS_INTEGRAL (targettype) && SPEC_USIGN(targettype) && right.min == right.max)
    {
      result->anything = false;
      result->min = right.min & ~result->knownbitsmask;
      result->max = right.max & ~result->knownbitsmask;
      result->knownbitsmask = ~0ull;
      result->knownbits = result->min;
    }
}

static void
recompute_node (cfg_t &G, unsigned int i, ebbIndex *ebbi, std::pair<std::queue<unsigned int>, std::set<unsigned int> > &todo, bool externchange, int end_it_quickly)
{
  iCode *const ic = G[i].ic;
  bool change = externchange;

  operand *left = IC_LEFT (ic);
  operand *right = IC_RIGHT (ic);
  struct valinfo oldleftvalinfo = getOperandValinfo (ic, left);
  struct valinfo oldrightvalinfo = getOperandValinfo (ic, right);

  if (!ic->valinfos)
    ic->valinfos = new struct valinfos;

  // Gather incoming information.
  typedef /*typename*/ boost::graph_traits<cfg_t>::in_edge_iterator in_iter_t;
  in_iter_t in, in_end;
  for (boost::tie(in, in_end) = boost::in_edges(i, G); in != in_end; ++in)
    change |= valinfos_unions (ic, G[*in]);

  typedef /*typename*/ boost::graph_traits<cfg_t>::out_edge_iterator out_iter_t;
  out_iter_t out, out_end;
  boost::tie(out, out_end) = boost::out_edges(i, G);

  if (!change || out == out_end)
    return;

  symbol *resultsym;
  if (IC_RESULT (ic) && IS_SYMOP (IC_RESULT (ic)) && !POINTER_SET (ic))
    resultsym = OP_SYMBOL (IC_RESULT (ic));
  else
    resultsym = 0;
  struct valinfo resultvalinfo;

  struct valinfo leftvalinfo = getOperandValinfo (ic, left);
  struct valinfo rightvalinfo = getOperandValinfo (ic, right);

  bool localchange = externchange || leftvalinfo != oldleftvalinfo || rightvalinfo != oldrightvalinfo;

  switch (ic->op)
    {
    case IFX:
    case JUMPTABLE:
      for(; out != out_end; ++out)
        {
          G[*out] = *ic->valinfos;
          if (todo.second.find (boost::target(*out, G)) == todo.second.end())
            {
              todo.first.push (boost::target(*out, G));
              todo.second.insert (boost::target(*out, G));
            }
        }
      if (ic->op == IFX && bitVectnBitsOn (OP_DEFS (ic->left)) == 1) // Propagate some info on the condition into the branches.
        {
          iCode *cic = (iCode *)hTabItemWithKey (iCodehTab, bitVectFirstBit (OP_DEFS (ic->left)));
          struct valinfo v = getOperandValinfo (ic, cic->left);
          if (cic->op == '>' && IS_ITEMP (cic->left) && !IS_OP_VOLATILE (cic->left) && IS_INTEGRAL (operandType (cic->left)) &&
            IS_OP_LITERAL (IC_RIGHT (cic)) && !v.anything && !v.nothing && operandLitValueUll(IC_RIGHT (cic)) < +1000)
            {
              long long litval = operandLitValueUll (IC_RIGHT (cic));
              struct valinfo v_true = v;
              struct valinfo v_false = v;
              v_true.min = std::max (v.min, litval + 1);
              v_false.max = std::min (v.max, litval);
              valinfoUpdate (&v_true);
              valinfoUpdate (&v_false);
              int key_true = IC_TRUE (ic) ? eBBWithEntryLabel(ebbi, IC_TRUE(ic))->sch->key : ic->next->key;
              int key_false = IC_FALSE (ic) ? eBBWithEntryLabel(ebbi, IC_FALSE(ic))->sch->key : ic->next->key;
              boost::tie(out, out_end) = boost::out_edges(i, G);
              for(; out != out_end; ++out)
                if (G[boost::target(*out, G)].ic->key == key_true)
                  G[*out].map[cic->left->key] = v_true;
                else if (G[boost::target(*out, G)].ic->key == key_false)
                  G[*out].map[cic->left->key] = v_false;
            }
          if (cic->op == '<' && IS_ITEMP (cic->left) && !IS_OP_VOLATILE (cic->left) && IS_INTEGRAL (operandType (cic->left)) &&
            IS_OP_LITERAL (IC_RIGHT (cic)) && !v.anything && !v.nothing && operandLitValueUll(IC_RIGHT (cic)) < 0xffffffff)
            {
              long long litval = operandLitValueUll (IC_RIGHT (cic));
              struct valinfo v_true = v;
              struct valinfo v_false = v;
              v_true.max = std::min (v.max, litval - 1);
              v_false.min = std::max (v.min, litval);
              valinfoUpdate (&v_true);
              valinfoUpdate (&v_false);
              int key_true = IC_TRUE (ic) ? eBBWithEntryLabel(ebbi, IC_TRUE(ic))->sch->key : ic->next->key;
              int key_false = IC_FALSE (ic) ? eBBWithEntryLabel(ebbi, IC_FALSE(ic))->sch->key : ic->next->key;
              boost::tie(out, out_end) = boost::out_edges(i, G);
              for(; out != out_end; ++out)
                if (G[boost::target(*out, G)].ic->key == key_true)
                  G[*out].map[cic->left->key] = v_true;
                else if (G[boost::target(*out, G)].ic->key == key_false)
                  G[*out].map[cic->left->key] = v_false;
            }
        }
      break;
    default:
      G[*out] = *ic->valinfos;
      if (ic->resultvalinfo)
        G[*out].map[ic->result->key] = *ic->resultvalinfo;

      if (resultsym)
        resultvalinfo = getTypeValinfo (operandType (IC_RESULT (ic)), true);
      else
        resultvalinfo.anything = true;

#ifdef DEBUG_GCP_ANALYSIS
      if (localchange && resultsym)
        {
          std::cout << "Recompute node " << i << " ic " << ic->key << "\n";
          std::cout << "getTypeValinfo: resultvalinfo anything " << resultvalinfo.anything << " knownbitsmask 0x" << std::hex << resultvalinfo.knownbitsmask << std::dec << " min " << resultvalinfo.min << "\n";
        }
#endif

      // Just use the very rough approximation from the type info only to speed up analysis.
      if (ic->op != '=' && ic->op != CAST && ic->op != '!' &&
        (end_it_quickly > 1 || end_it_quickly > 0 && (ic->op == '+' || ic->op == '-')))
        {
          if (left && !(IS_INTEGRAL (operandType (left)) && bitsForType (operandType (left)) < 64 && IS_OP_LITERAL (left)))
            leftvalinfo = getTypeValinfo (operandType (left), true);
          if (right && !(IS_INTEGRAL (operandType (right)) && bitsForType (operandType (right)) < 64 && IS_OP_LITERAL (right)))
            rightvalinfo = getTypeValinfo (operandType (right), true);
        }

      if (!localchange) // Input didn't change. No need to recompute result.
        resultsym = 0;
      else if (IS_OP_VOLATILE (ic->result)) // No point trying to find out what we write to a volatile operand. At the next use, it could be anything, anyway.
        ;
      else if (ic->op == '!')
        {
          resultvalinfo.nothing = leftvalinfo.nothing;
          resultvalinfo.anything = false;
          resultvalinfo.min = 0;
          resultvalinfo.max = 1;
          resultvalinfo.knownbitsmask = ~1ull;
          resultvalinfo.knownbits = 0ull;
          if (!leftvalinfo.anything && (leftvalinfo.min > 0 || leftvalinfo.max < 0))
            resultvalinfo.max = 0;
          else if (!leftvalinfo.anything && leftvalinfo.min == 0 && leftvalinfo.max == 0)
            resultvalinfo.min = 1;
        }
      else if (ic-> op == UNARYMINUS)
        {
          struct valinfo z;
          z.nothing = false;
          z.anything = false;
          z.min = z.max = 0;
          valinfoMinus (&resultvalinfo, operandType (ic->result), z, leftvalinfo);
        }
      else if (ic->op == '<' || ic->op == GE_OP)
        {
          resultvalinfo.nothing = leftvalinfo.nothing || rightvalinfo.nothing;
          resultvalinfo.anything = false;
          resultvalinfo.min = 0;
          resultvalinfo.max = 1;
          resultvalinfo.knownbitsmask = ~1ull;
          resultvalinfo.knownbits = 0ull;
          if (!leftvalinfo.anything && !rightvalinfo.anything)
            {
              if (leftvalinfo.max < rightvalinfo.min)
                resultvalinfo.min = resultvalinfo.max = (ic->op == '<');
              else if (leftvalinfo.min >= rightvalinfo.max)
                resultvalinfo.min = resultvalinfo.max = (ic->op == GE_OP);
            }
        }
      else if (ic->op == '>' || ic->op == LE_OP)
        {
          resultvalinfo.nothing = leftvalinfo.nothing || rightvalinfo.nothing;
          resultvalinfo.anything = false;
          resultvalinfo.min = 0;
          resultvalinfo.max = 1;
          resultvalinfo.knownbitsmask = ~1ull;
          resultvalinfo.knownbits = 0ull;
          if (!leftvalinfo.anything && !rightvalinfo.anything)
            {
              if (leftvalinfo.min > rightvalinfo.max)
                resultvalinfo.min = resultvalinfo.max = (ic->op == '>');
              else if (leftvalinfo.max <= rightvalinfo.min)
                resultvalinfo.min = resultvalinfo.max = (ic->op == LE_OP);
            }
        }
      else if (ic->op == NE_OP || ic->op == EQ_OP)
        {
          resultvalinfo.nothing = leftvalinfo.nothing || rightvalinfo.nothing;
          resultvalinfo.anything = false;
          resultvalinfo.min = 0;
          resultvalinfo.max = 1;
          resultvalinfo.knownbitsmask = ~1ull;
          resultvalinfo.knownbits = 0ull;
          if (!leftvalinfo.anything && !rightvalinfo.anything && leftvalinfo.min == leftvalinfo.max && rightvalinfo.min == rightvalinfo.max)
            {
              bool one = (leftvalinfo.min == rightvalinfo.min) ^ (ic->op == NE_OP);
              resultvalinfo.min = one;
              resultvalinfo.max = one;
            }
        }
      else if (ic->op == '+')
        valinfoPlus (&resultvalinfo, operandType (ic->result), leftvalinfo, rightvalinfo);
      else if (ic->op == '-')
        valinfoMinus (&resultvalinfo, operandType (ic->result), leftvalinfo, rightvalinfo);
      else if (ic->op == '*')
        valinfoMult (&resultvalinfo, leftvalinfo, rightvalinfo);
      else if (ic->op == '/')
        valinfoDiv (&resultvalinfo, leftvalinfo, rightvalinfo);
      else if (ic->op == '%')
        valinfoMod (&resultvalinfo, leftvalinfo, rightvalinfo);
      else if (ic->op == '|')
        valinfoOr (&resultvalinfo, leftvalinfo, rightvalinfo);
      else if (ic->op == BITWISEAND)
        valinfoAnd (&resultvalinfo, operandType (ic->result), leftvalinfo, rightvalinfo);
      else if (ic->op == '^')
        valinfoXor (&resultvalinfo, leftvalinfo, rightvalinfo);
      else if (ic->op == GETABIT)
        valinfoGetABit (&resultvalinfo, leftvalinfo, rightvalinfo);
      else if (ic->op == LEFT_OP)
        valinfoLeft (&resultvalinfo, leftvalinfo, rightvalinfo);
      else if (ic->op == RIGHT_OP)
        valinfoRight (&resultvalinfo, leftvalinfo, rightvalinfo);
      else if (ic->op == '=' && !POINTER_SET (ic) || ic->op == CAST)
        //resultvalinfo = rightvalinfo; // Doesn't work for = - sometimes = with mismatched types arrive here.
        valinfoCast (&resultvalinfo, operandType (IC_RESULT (ic)), rightvalinfo);

      if (resultsym)
        {
          valinfoUpdate (&resultvalinfo);
#ifdef DEBUG_GCP_ANALYSIS
          std::cout << "resultvalinfo anything " << resultvalinfo.anything << " knownbitsmask 0x" << std::hex << resultvalinfo.knownbitsmask << " knownbits 0x" << resultvalinfo.knownbits << std::dec << " min " << resultvalinfo.min << " max " << resultvalinfo.max << "\n";
#endif
          if (!ic->resultvalinfo)
            ic->resultvalinfo = new struct valinfo;
          *ic->resultvalinfo = resultvalinfo;
          G[*out].map[ic->result->key] = resultvalinfo;
        }
      if (todo.second.find (boost::target(*out, G)) == todo.second.end())
        {
          todo.first.push (boost::target(*out, G));
          todo.second.insert (boost::target(*out, G));
        }
    }
}

// Calculate valinfos for all iCodes in function.
void
recomputeValinfos (iCode *sic, ebbIndex *ebbi, const char *suffix)
{
#ifdef DEBUG_GCP_ANALYSIS
  std::cout << "recomputeValinfos at " << (currFunc ? currFunc->name : "[NOFUNC]") << "\n"; std::cout.flush();
#endif

  unsigned long max_rounds = 18000; // Rapidly end analysis once this number of rounds has been exceeded.

  cfg_t G;

  create_cfg_genconstprop(G, sic, ebbi);

  std::pair <std::queue<unsigned int>, std::set<unsigned int> > todo; // Nodes where valinfos need to be updated. We need a pair of a queue and a set to implement a queue with uniqe entries. A plain set wouldn't work, as we'd be working on some nodes all the time while never getting to others before we reach the round limit.

  // Process each node at least once.
  for (unsigned int i = 0; i < boost::num_vertices (G); i++)
    {
      delete G[i].ic->valinfos;
      G[i].ic->valinfos = NULL;
      delete G[i].ic->resultvalinfo;
      G[i].ic->resultvalinfo = NULL;
      recompute_node (G, i, ebbi, todo, true, 0);
    }

  // Forward pass to get first approximation.
  for (unsigned long round = 0; !todo.first.empty (); round++)
    {
      // Take next node that needs updating.
      unsigned int i = todo.first.front ();
      todo.first.pop ();
      todo.second.erase (i);

#ifdef DEBUG_GCP_ANALYSIS
      std::cout << "Round " << round << " node " << i << " ic " << G[i].ic->key << "\n"; std::cout.flush();
#endif

      recompute_node (G, i, ebbi, todo, false, (round >= max_rounds) + (round >= max_rounds * 2));
    }

  // Refinement backward pass.
  // TODO

  if(options.dump_graphs)
    dump_cfg_genconstprop(G, suffix);
}

// Try to replace operands by constants
static void
optimizeValinfoConst (iCode *sic)
{
#ifdef DEBUG_GCP_OPT
  std::cout << "optimizeValinfoConst at " << (currFunc ? currFunc->name : "[NOFUNC]") << "\n"; std::cout.flush();
#endif
  for (iCode *ic = sic; ic; ic = ic->next)
    {
      if (SKIP_IC2 (ic))
        ;
      else
        {
          operand *left = IC_LEFT (ic);
          operand *right = IC_RIGHT (ic);
          operand *result = IC_RESULT (ic);
          const valinfo vleft = getOperandValinfo (ic, left);
          const valinfo vright = getOperandValinfo (ic, right);
          if (ic->resultvalinfo && !ic->resultvalinfo->anything && ic->resultvalinfo->min == ic->resultvalinfo->max &&
            !(ic->op == '=' && IS_OP_LITERAL (right)) && !POINTER_SET (ic))
            {
              const valinfo &vresult = *ic->resultvalinfo;
#ifdef DEBUG_GCP_OPT
              std::cout << "Replace result at " << ic->key << ". anything " << vresult.anything << " min " << vresult.min << " max " << vresult.max << "\n";
#endif
              detachiCodeOperand (&ic->left, ic);
              detachiCodeOperand (&ic->right, ic);
              ic->op = '=';
              ic->right = operandFromValue (valCastLiteral (operandType (result), vresult.min, vresult.min), false);
            }
          else
            {
              if (left && IS_ITEMP (left) && !vleft.anything && vleft.min == vleft.max)
                {
#ifdef DEBUG_GCP_OPT
                  std::cout << "Replace left (" << OP_SYMBOL(left)->name << "), key " << left->key << " at " << ic->key << "\n";std::cout << "anything " << vleft.anything << " min " << vleft.min << " max " << vleft.max << "\n";
#endif
                  attachiCodeOperand (operandFromValue (valCastLiteral (operandType (left), vleft.min, vleft.min), false), &ic->left, ic);
                }
              if (right && IS_ITEMP (right) && !vright.anything && vright.min == vright.max)
                {
#ifdef DEBUG_GCP_OPT
                  std::cout << "Replace right at " << ic->key << "\n";std::cout << "anything " << vleft.anything << " min " << vleft.min << " max " << vleft.max << "\n";
#endif
                  attachiCodeOperand (operandFromValue (valCastLiteral (operandType (right), vright.min, vright.min), false), &ic->right, ic);
                }
            }
          
        }
    }
}

static void
reTypeOp (operand *op, sym_link *newtype)
{
#if 0
  std::cout << "reType Op to "; std::cout.flush(); printTypeChain (newtype, 0);
#endif
  if (IS_OP_LITERAL (op))
    {
      op->svt.valOperand = valCastLiteral (newtype, operandLitValue (op), operandLitValueUll (op));
      return;
    }

  // Replace at uses.
  bitVect *uses = bitVectCopy (OP_USES (op));
  for (int key = bitVectFirstBit (uses); bitVectnBitsOn (uses); bitVectUnSetBit (uses, key), key = bitVectFirstBit (uses))
    {
      iCode *uic = (iCode *)hTabItemWithKey (iCodehTab, key);
      wassert (uic);
      if (isOperandEqual (op, uic->left))
        setOperandType (uic->left, newtype);
      if (isOperandEqual (op, uic->right))
        setOperandType (uic->right, newtype);
      if (POINTER_SET (uic) && isOperandEqual (op, uic->result))
        setOperandType (uic->result, newtype);
    }
  freeBitVect (uses);

  // Replace at definitions.
  bitVect *defs = bitVectCopy (OP_DEFS (op));
  for (int key = bitVectFirstBit (defs); bitVectnBitsOn (defs); bitVectUnSetBit (defs, key), key = bitVectFirstBit (defs))
    {
      iCode *dic = (iCode *)hTabItemWithKey (iCodehTab, key);
      wassert (dic && dic->result && isOperandEqual (op, dic->result));
      setOperandType (dic->result, newtype);
      if (dic->op == '=' && IS_OP_LITERAL (dic->right))
        reTypeOp (dic->right, newtype);
      else if (dic->op == CAST || dic->op == '=')
        {
          dic->op = CAST;
          dic->left = operandFromLink (newtype);
        }
    }
  freeBitVect (defs);
}

// todo: Remove this, use stdc_bit_width instead once we can assume C2X support on host compiler
#ifndef ULLONG_WIDTH // Also a C2X feature
#define ULLONG_WIDTH (CHAR_BIT * sizeof (unsigned long long))
#endif
unsigned int my_stdc_bit_width (unsigned long long value)
{
  unsigned int width = 0;
  for (int i = 0; i < ULLONG_WIDTH; i++)
    if (value & (1ull << i))
      width = (i + 1);
  return width;
}

static void
optimizeNarrowOpNet (iCode *ic)
{
  if (!ic || POINTER_SET(ic) || !ic->result || !ic->resultvalinfo || !IS_ITEMP (ic->result))
    return;

  std::set <operand *> net, checknet;
  net.insert (ic->result);
  checknet.insert (ic->result);

  struct valinfo v = *(ic->resultvalinfo);
  unsigned int ptropwidth = 0; // Width of pointers that an integer net is added to (only bits within address space count, not tag bits).

#if 0
  std::cout << "optimizeNarrowOpNet at ic " << ic->key << ": " << OP_SYMBOL (ic->result)->name << "\n"; std::cout.flush();
#endif

  while (!checknet.empty())
    {
      operand *op = *checknet.begin();
      checknet.erase (op);

      if (!IS_INTEGRAL (operandType (ic->result)) && !IS_GENPTR (operandType (ic->result)))
        return;
      if (IS_OP_LITERAL (op))
        continue;
      if (!IS_ITEMP (op))
        return;

      bitVect *defs = bitVectCopy (OP_DEFS (op));
      for (int key = bitVectFirstBit (defs); bitVectnBitsOn (defs); bitVectUnSetBit (defs, key), key = bitVectFirstBit (defs))
        {
          iCode *dic = (iCode *)hTabItemWithKey (iCodehTab, key);
          if (!dic || !dic->resultvalinfo)  // Looks like some earlier optimization left bad data. Abort.
            return;
          if (dic->op == CAST || dic->op == '=' && !POINTER_SET (dic)) // Def ok: we could just change to suitable cast.
            ;
          else if (dic->op == ADDRESS_OF)
            ;
          else if (dic->op == '+' || dic->op == '-' || dic->op == '^' || dic->op == '|' || dic->op == BITWISEAND)
            {
              wassert (isOperandEqual (dic->result, op));
              if (net.find(dic->left) == net.end() && IS_PTR (operandType (ic->result)) == IS_PTR (operandType (dic->left)))
                {
                  net.insert (dic->left);
                  checknet.insert (dic->left);
                }
              if (net.find(dic->right) == net.end() && IS_PTR (operandType (ic->result)) == IS_PTR (operandType (dic->right)))
                {
                  net.insert (dic->right);
                  checknet.insert (dic->right);
                }
            }
          else
            return;
          valinfo_union (&v, *dic->resultvalinfo);
        }
      freeBitVect (defs);

      bitVect *uses = bitVectCopy (OP_USES (op));
      if (!bitVectnBitsOn (uses)) // An iTemp without uses! stay away for now!
        return;
      for (int key = bitVectFirstBit (uses); bitVectnBitsOn (uses); bitVectUnSetBit (uses, key), key = bitVectFirstBit (uses))
        {
          iCode *uic = (iCode *)hTabItemWithKey (iCodehTab, key);
          if (!uic)
            bitVectUnSetBit (OP_USES (op), key); // Looks like some earlier optimization didn't clean up properly. Do it now.
          else if (uic->op == CAST && !IS_FLOAT (operandType (uic->result)))
            valinfo_union (&v, getOperandValinfo (uic, uic->right));
          else if (uic->op == EQ_OP || uic->op == NE_OP || uic->op == '<' || uic->op == LE_OP || uic->op == '>' || uic->op == GE_OP)
            {
              if (isOperandEqual (uic->left, op) && !isOperandEqual (uic->right, op))
                {
                  valinfo_union (&v, getOperandValinfo (uic, uic->right));
                  if (net.find(uic->right) == net.end())
                    {
                      net.insert (uic->right);
                      checknet.insert (uic->right);
                    }
                }
              if (!isOperandEqual (uic->left, op) && isOperandEqual (uic->right, op))
                {
                  valinfo_union (&v, getOperandValinfo (uic, uic->left));
                  if (net.find(uic->left) == net.end())
                    {
                      net.insert (uic->left);
                      checknet.insert (uic->left);
                    }
                }
            }
          else if (uic->op == '+' || uic->op == '-' || uic->op == '^' || uic->op == '|' || uic->op == BITWISEAND)
            {
              if (!IS_PTR (operandType (op)) && IS_PTR (operandType (uic->result)) && v.min < 0) // Avoid breaking the addition of signed offsets to pointers (bug #3807).
                {
                  unsigned int pwidth = bitsForType (operandType (uic->result));
                  // mcs51 has 24 bit pointers, but at most 16 bits in each individual address space.
                  if (TARGET_IS_MCS51 && pwidth > 16)
                    pwidth = 16;
                  if (TARGET_IS_DS390 && pwidth > 24)
                    pwidth = 24;
                  // The pdk ports are actually named for the maximum number of address bits in their biggest address space.
                  else if (TARGET_IS_PDK13 && pwidth > 13)
                    pwidth = 13;
                  else if (TARGET_IS_PDK14 && pwidth > 14)
                    pwidth = 14;
                  else if (TARGET_IS_PDK15 && pwidth > 15)
                    pwidth = 15;
                  else if (TARGET_IS_PDK16 && pwidth > 16)
                    pwidth = 16;
                  if (pwidth > ptropwidth)
                    ptropwidth = pwidth;
                }
              if (isOperandEqual (uic->left, op) && !IS_PTR (operandType (uic->result)))
                {
                  if (net.find(uic->right) == net.end())
                    {
                      net.insert (uic->right);
                      checknet.insert (uic->right);
                    }
                }
              if (isOperandEqual (uic->right, op) && !IS_PTR (operandType (uic->result)) )
                {
                  if (net.find(uic->left) == net.end())
                    {
                      net.insert (uic->left);
                      checknet.insert (uic->left);
                    }
                }
              if (IS_PTR (operandType (ic->result)) == IS_PTR (operandType (uic->result)))
                {
                  if(net.find(uic->result) == net.end())
                  {
                    net.insert (uic->result);
                    checknet.insert (uic->result);
                  }
                }
            }
          else if ((uic->op == LEFT_OP || uic->op == RIGHT_OP || uic->op == ROT) && !isOperandEqual (uic->left, op))
            ;
          else if ((uic->op == LEFT_OP || uic->op == RIGHT_OP || uic->op == UNARYMINUS || uic->op == '~') && isOperandEqual (uic->left, op)) // Not ROT, since the size affects semantics.
            {
              if (net.find(uic->result) == net.end())
                {
                  net.insert (uic->result);
                  checknet.insert (uic->result);
                }
            }
          else if (uic->op == '!' || uic->op == IFX)
            ;
          else if (uic->op == GET_VALUE_AT_ADDRESS && !isOperandEqual (IS_INTEGRAL (operandType (op)) ? uic->left : uic->right, op))
            ;
          else if (POINTER_SET (uic) && isOperandEqual (uic->result, op))
            ;
          else 
            return;
        }
      freeBitVect (uses);
    }

  if (v.anything)
    return;

  sym_link *newtype;
  if (IS_INTEGRAL (operandType (ic->result)) && v.min >= 0) // Try to use an unsigned type first - they tend to be more efficient.
    {
      unsigned int width = my_stdc_bit_width (v.max);
      width = ((width + 7) & (-8)); // Round up to multiple of 8.
      if (width < 8) // If analysis showed that this is a constant 0, make it 8 bits, still, instead of 0.
        width = 8;
      if (width >= bitsForType (operandType (ic->result)))
        return;
      if (width > port->s.bitint_maxwidth)
        return;
#if 0
      std::cout << "Found optimizeable unoptimized unsigned integer net! New width: " << width << "\n";
#endif
      newtype = newBitIntLink (width);
      SPEC_USIGN (newtype) = true;
    }
  else if (IS_INTEGRAL (operandType (ic->result)) && v.min < 0)
    {
      unsigned int width = my_stdc_bit_width (v.max);
      if (my_stdc_bit_width (-v.min) > width)
        width = my_stdc_bit_width (-v.min);
      width++; // Add one for the "sign bit".
      if (ptropwidth > width)
        width = ptropwidth;
      width = ((width + 7) & (-8)); // Round up to multiple of 8.
      if (width >= bitsForType (operandType (ic->result)))
        return;
      if (width > port->s.bitint_maxwidth)
        return;
#if 0
      std::cout << "Found optimizeable unoptimized signed integer net! New width: " << width << "\n";
#endif
      newtype = newBitIntLink (width);
      SPEC_USIGN (newtype) = false;
    }
  else if (IS_GENPTR (operandType (ic->result)) && v.min >= 0 && (TARGET_IS_MCS51 || TARGET_PDK_LIKE))
    {
      if (TARGET_IS_MCS51 && (v.knownbitsmask & 0xff0000) != 0xff0000) // Check if we fully know the GPByte, and thus the intrinsic named address space this pointer points to.
        return;
      if (TARGET_PDK_LIKE && !(v.knownbitsmask & 0x8000)) // Check if we know the topmost bit, and thus the intrinsic named address space this pointer points to.
        return;

      newtype = copyLinkChain (operandType (ic->result));

      if (TARGET_IS_MCS51)
        {
          int gpbyte = (v.knownbits & 0xff0000) >> 16;
          if (gpbyte == GPTYPE_NEAR)
            DCL_TYPE (newtype) = IPOINTER;
          else if (gpbyte == GPTYPE_XSTACK)
            DCL_TYPE (newtype) = PPOINTER;
          else if (gpbyte == GPTYPE_FAR)
            DCL_TYPE (newtype) = FPOINTER;
          else if (gpbyte == GPTYPE_CODE)
            DCL_TYPE (newtype) = CPOINTER;
          else
            {
              std::cerr << "Odd gpbyte " << std::hex << gpbyte << "\n";
              wassert (0);
            }
        }
      else if (TARGET_PDK_LIKE)
        {
          if (v.knownbits & 0x8000)
            DCL_TYPE (newtype) = CPOINTER;
          else
            DCL_TYPE (newtype) = POINTER;
        }
      else
        wassert (0);
#if 0
      std::cout << "Found optimizeable unoptimized pointer net!\n";
#endif
    }
  else
    return;

  for(std::set<operand *>::iterator i = net.begin(); i != net.end(); ++i)
    reTypeOp (*i, newtype);
}

static void
optimizeMult (iCode *ic)
{
  operand *left = IC_LEFT (ic);
  operand *right = IC_RIGHT (ic);
  operand *result = IC_RESULT (ic);

  sym_link *oldoptype = operandType (left);
  sym_link *oldresulttype = operandType (result);

  struct valinfo leftv = getOperandValinfo (ic, left);
  struct valinfo rightv = getOperandValinfo (ic, right);
  struct valinfo resultv = *ic->resultvalinfo;

  if (leftv.anything || rightv.anything || resultv.anything || leftv.min < 0 || rightv.min < 0 || leftv.max > 0xffff || rightv.max > 0xffff || resultv.max > 0xffff)
    return;

  if (!IS_INTEGRAL (oldresulttype) || bitsForType (oldoptype) <= 8 || bitsForType (oldresulttype) <= 8)
    return;

  if (bitsForType (oldresulttype) <= 16 && (leftv.max > 0xff || rightv.max > 0xff))
    return;

  if (ic->op == '*' && bitsForType (oldresulttype) <= 16)
    return;

  sym_link *newoptype;
  sym_link *newresulttype;
  if (leftv.max <= 0xff && rightv.max <= 0xff) // Use unsigned char, as that allows 8x8->16 multiplication.
    {
      newoptype = newCharLink ();
      SPEC_USIGN (newoptype) = true;
      newresulttype = (resultv.max <= 0xff) ? newCharLink () : newIntLink ();
      SPEC_USIGN (newresulttype) = true;
    }
  else
    {
      newoptype = newBitIntLink (16);
      SPEC_USIGN (newoptype) = true;
      newresulttype = newBitIntLink (16);
      SPEC_USIGN (newresulttype) = true;
    }
  
  prependCast (ic, left, newoptype, 0);
  prependCast (ic, right, newoptype, 0);
  appendCast (ic, newresulttype, 0);
}

// Try to narrow operations
static void
optimizeValinfoNarrow (iCode *sic)
{
#ifdef DEBUG_GCP_OPT
  std::cout << "optimizeValinfoNarrow at " << (currFunc ? currFunc->name : "[NOFUNC]") << "\n";
#endif

  for (iCode *ic = sic; ic; ic = ic->next)
    optimizeNarrowOpNet (ic);

  for (iCode *ic = sic; ic; ic = ic->next)
      if (ic->op == '*' || ic->op == '/' || ic->op == '%')
        optimizeMult (ic);
}

// Do machine-independent optimizations based on valinfos.
void
optimizeValinfo (iCode *sic)
{
  optimizeValinfoConst (sic);
  optimizeValinfoNarrow (sic);
}