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/* Operations with affine combinations of trees.

   Copyright (C) 2005, 2007, 2008 Free Software Foundation, Inc.

This file is part of GCC.

GCC 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 3, or (at your option) any

later version.

GCC 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 GCC; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tm.h"

#include "tree.h"

#include "rtl.h"

#include "tm_p.h"

#include "hard-reg-set.h"

#include "output.h"

#include "diagnostic.h"

#include "tree-dump.h"

#include "pointer-set.h"

#include "tree-affine.h"

#include "gimple.h"

#include "flags.h"

/* Extends CST as appropriate for the affine combinations COMB.  */

double_int

double_int_ext_for_comb (double_int cst, aff_tree *comb)

{

  return double_int_sext (cst, TYPE_PRECISION (comb->type));

}

/* Initializes affine combination COMB so that its value is zero in TYPE.  */

static void

aff_combination_zero (aff_tree *comb, tree type)

{

  comb->type = type;

  comb->offset = double_int_zero;

  comb->n = 0;

  comb->rest = NULL_TREE;

}

/* Sets COMB to CST.  */

void

aff_combination_const (aff_tree *comb, tree type, double_int cst)

{

  aff_combination_zero (comb, type);

  comb->offset = double_int_ext_for_comb (cst, comb);

}

/* Sets COMB to single element ELT.  */

void

aff_combination_elt (aff_tree *comb, tree type, tree elt)

{

  aff_combination_zero (comb, type);

  comb->n = 1;

  comb->elts[0].val = elt;

  comb->elts[0].coef = double_int_one;

}

/* Scales COMB by SCALE.  */

void

aff_combination_scale (aff_tree *comb, double_int scale)

{

  unsigned i, j;

  scale = double_int_ext_for_comb (scale, comb);

  if (double_int_one_p (scale))

    return;

  if (double_int_zero_p (scale))

    {

      aff_combination_zero (comb, comb->type);

      return;

    }

  comb->offset

    = double_int_ext_for_comb (double_int_mul (scale, comb->offset), comb);

  for (i = 0, j = 0; i < comb->n; i++)

    {

      double_int new_coef;

      new_coef

        = double_int_ext_for_comb (double_int_mul (scale, comb->elts[i].coef),

                                   comb);

      /* A coefficient may become zero due to overflow.  Remove the zero

         elements.  */

      if (double_int_zero_p (new_coef))

        continue;

      comb->elts[j].coef = new_coef;

      comb->elts[j].val = comb->elts[i].val;

      j++;

    }

  comb->n = j;

  if (comb->rest)

    {

      tree type = comb->type;

      if (POINTER_TYPE_P (type))

        type = sizetype;

      if (comb->n < MAX_AFF_ELTS)

        {

          comb->elts[comb->n].coef = scale;

          comb->elts[comb->n].val = comb->rest;

          comb->rest = NULL_TREE;

          comb->n++;

        }

      else

        comb->rest = fold_build2 (MULT_EXPR, type, comb->rest,

                                  double_int_to_tree (type, scale));

    }

}

/* Adds ELT * SCALE to COMB.  */

void

aff_combination_add_elt (aff_tree *comb, tree elt, double_int scale)

{

  unsigned i;

  tree type;

  scale = double_int_ext_for_comb (scale, comb);

  if (double_int_zero_p (scale))

    return;

  for (i = 0; i < comb->n; i++)

    if (operand_equal_p (comb->elts[i].val, elt, 0))

      {

        double_int new_coef;

        new_coef = double_int_add (comb->elts[i].coef, scale);

        new_coef = double_int_ext_for_comb (new_coef, comb);

        if (!double_int_zero_p (new_coef))

          {

            comb->elts[i].coef = new_coef;

            return;

          }

        comb->n--;

        comb->elts[i] = comb->elts[comb->n];

        if (comb->rest)

          {

            gcc_assert (comb->n == MAX_AFF_ELTS - 1);

            comb->elts[comb->n].coef = double_int_one;

            comb->elts[comb->n].val = comb->rest;

            comb->rest = NULL_TREE;

            comb->n++;

          }

        return;

      }

  if (comb->n < MAX_AFF_ELTS)

    {

      comb->elts[comb->n].coef = scale;

      comb->elts[comb->n].val = elt;

      comb->n++;

      return;

    }

  type = comb->type;

  if (POINTER_TYPE_P (type))

    type = sizetype;

  if (double_int_one_p (scale))

    elt = fold_convert (type, elt);

  else

    elt = fold_build2 (MULT_EXPR, type,

                       fold_convert (type, elt),

                       double_int_to_tree (type, scale));

  if (comb->rest)

    comb->rest = fold_build2 (PLUS_EXPR, type, comb->rest,

                              elt);

  else

    comb->rest = elt;

}

/* Adds CST to C.  */

static void

aff_combination_add_cst (aff_tree *c, double_int cst)

{

  c->offset = double_int_ext_for_comb (double_int_add (c->offset, cst), c);

}

/* Adds COMB2 to COMB1.  */

void

aff_combination_add (aff_tree *comb1, aff_tree *comb2)

{

  unsigned i;

  aff_combination_add_cst (comb1, comb2->offset);

  for (i = 0; i < comb2->n; i++)

    aff_combination_add_elt (comb1, comb2->elts[i].val, comb2->elts[i].coef);

  if (comb2->rest)

    aff_combination_add_elt (comb1, comb2->rest, double_int_one);

}

/* Converts affine combination COMB to TYPE.  */

void

aff_combination_convert (aff_tree *comb, tree type)

{

  unsigned i, j;

  tree comb_type = comb->type;

  if  (TYPE_PRECISION (type) > TYPE_PRECISION (comb_type))

    {

      tree val = fold_convert (type, aff_combination_to_tree (comb));

      tree_to_aff_combination (val, type, comb);

      return;

    }

  comb->type = type;

  if (comb->rest && !POINTER_TYPE_P (type))

    comb->rest = fold_convert (type, comb->rest);

  if (TYPE_PRECISION (type) == TYPE_PRECISION (comb_type))

    return;

  comb->offset = double_int_ext_for_comb (comb->offset, comb);

  for (i = j = 0; i < comb->n; i++)

    {

      double_int new_coef = double_int_ext_for_comb (comb->elts[i].coef, comb);

      if (double_int_zero_p (new_coef))

        continue;

      comb->elts[j].coef = new_coef;

      comb->elts[j].val = fold_convert (type, comb->elts[i].val);

      j++;

    }

  comb->n = j;

  if (comb->n < MAX_AFF_ELTS && comb->rest)

    {

      comb->elts[comb->n].coef = double_int_one;

      comb->elts[comb->n].val = comb->rest;

      comb->rest = NULL_TREE;

      comb->n++;

    }

}

/* Splits EXPR into an affine combination of parts.  */

void

tree_to_aff_combination (tree expr, tree type, aff_tree *comb)

{

  aff_tree tmp;

  enum tree_code code;

  tree cst, core, toffset;

  HOST_WIDE_INT bitpos, bitsize;

  enum machine_mode mode;

  int unsignedp, volatilep;

  STRIP_NOPS (expr);

  code = TREE_CODE (expr);

  switch (code)

    {

    case INTEGER_CST:

      aff_combination_const (comb, type, tree_to_double_int (expr));

      return;

    case POINTER_PLUS_EXPR:

      tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);

      tree_to_aff_combination (TREE_OPERAND (expr, 1), sizetype, &tmp);

      aff_combination_add (comb, &tmp);

      return;

    case PLUS_EXPR:

    case MINUS_EXPR:

      tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);

      tree_to_aff_combination (TREE_OPERAND (expr, 1), type, &tmp);

      if (code == MINUS_EXPR)

        aff_combination_scale (&tmp, double_int_minus_one);

      aff_combination_add (comb, &tmp);

      return;

    case MULT_EXPR:

      cst = TREE_OPERAND (expr, 1);

      if (TREE_CODE (cst) != INTEGER_CST)

        break;

      tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);

      aff_combination_scale (comb, tree_to_double_int (cst));

      return;

    case NEGATE_EXPR:

      tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);

      aff_combination_scale (comb, double_int_minus_one);

      return;

    case BIT_NOT_EXPR:

      /* ~x = -x - 1 */

      tree_to_aff_combination (TREE_OPERAND (expr, 0), type, comb);

      aff_combination_scale (comb, double_int_minus_one);

      aff_combination_add_cst (comb, double_int_minus_one);

      return;

    case ADDR_EXPR:

      core = get_inner_reference (TREE_OPERAND (expr, 0), &bitsize, &bitpos,

                                  &toffset, &mode, &unsignedp, &volatilep,

                                  false);

      if (bitpos % BITS_PER_UNIT != 0)

        break;

      aff_combination_const (comb, type,

                             uhwi_to_double_int (bitpos / BITS_PER_UNIT));

      core = build_fold_addr_expr (core);

      if (TREE_CODE (core) == ADDR_EXPR)

        aff_combination_add_elt (comb, core, double_int_one);

      else

        {

          tree_to_aff_combination (core, type, &tmp);

          aff_combination_add (comb, &tmp);

        }

      if (toffset)

        {

          tree_to_aff_combination (toffset, type, &tmp);

          aff_combination_add (comb, &tmp);

        }

      return;

    default:

      break;

    }

  aff_combination_elt (comb, type, expr);

}

/* Creates EXPR + ELT * SCALE in TYPE.  EXPR is taken from affine

   combination COMB.  */

static tree

add_elt_to_tree (tree expr, tree type, tree elt, double_int scale,

                 aff_tree *comb)

{

  enum tree_code code;

  tree type1 = type;

  if (POINTER_TYPE_P (type))

    type1 = sizetype;

  scale = double_int_ext_for_comb (scale, comb);

  elt = fold_convert (type1, elt);

  if (double_int_one_p (scale))

    {

      if (!expr)

        return fold_convert (type, elt);

      if (POINTER_TYPE_P (type))

        return fold_build2 (POINTER_PLUS_EXPR, type, expr, elt);

      return fold_build2 (PLUS_EXPR, type, expr, elt);

    }

  if (double_int_minus_one_p (scale))

    {

      if (!expr)

        return fold_convert (type, fold_build1 (NEGATE_EXPR, type1, elt));

      if (POINTER_TYPE_P (type))

        {

          elt = fold_build1 (NEGATE_EXPR, type1, elt);

          return fold_build2 (POINTER_PLUS_EXPR, type, expr, elt);

        }

      return fold_build2 (MINUS_EXPR, type, expr, elt);

    }

  if (!expr)

    return fold_convert (type,

                         fold_build2 (MULT_EXPR, type1, elt,

                                      double_int_to_tree (type1, scale)));

  if (double_int_negative_p (scale))

    {

      code = MINUS_EXPR;

      scale = double_int_neg (scale);

    }

  else

    code = PLUS_EXPR;

  elt = fold_build2 (MULT_EXPR, type1, elt,

                     double_int_to_tree (type1, scale));

  if (POINTER_TYPE_P (type))

    {

      if (code == MINUS_EXPR)

        elt = fold_build1 (NEGATE_EXPR, type1, elt);

      return fold_build2 (POINTER_PLUS_EXPR, type, expr, elt);

    }

  return fold_build2 (code, type, expr, elt);

}

/* Makes tree from the affine combination COMB.  */

tree

aff_combination_to_tree (aff_tree *comb)

{

  tree type = comb->type;

  tree expr = comb->rest;

  unsigned i;

  double_int off, sgn;

  tree type1 = type;

  if (POINTER_TYPE_P (type))

    type1 = sizetype;

  gcc_assert (comb->n == MAX_AFF_ELTS || comb->rest == NULL_TREE);

  for (i = 0; i < comb->n; i++)

    expr = add_elt_to_tree (expr, type, comb->elts[i].val, comb->elts[i].coef,

                            comb);

  /* Ensure that we get x - 1, not x + (-1) or x + 0xff..f if x is

     unsigned.  */

  if (double_int_negative_p (comb->offset))

    {

      off = double_int_neg (comb->offset);

      sgn = double_int_minus_one;

    }

  else

    {

      off = comb->offset;

      sgn = double_int_one;

    }

  return add_elt_to_tree (expr, type, double_int_to_tree (type1, off), sgn,

                          comb);

}

/* Copies the tree elements of COMB to ensure that they are not shared.  */

void

unshare_aff_combination (aff_tree *comb)

{

  unsigned i;

  for (i = 0; i < comb->n; i++)

    comb->elts[i].val = unshare_expr (comb->elts[i].val);

  if (comb->rest)

    comb->rest = unshare_expr (comb->rest);

}

/* Remove M-th element from COMB.  */

void

aff_combination_remove_elt (aff_tree *comb, unsigned m)

{

  comb->n--;

  if (m <= comb->n)

    comb->elts[m] = comb->elts[comb->n];

  if (comb->rest)

    {

      comb->elts[comb->n].coef = double_int_one;

      comb->elts[comb->n].val = comb->rest;

      comb->rest = NULL_TREE;

      comb->n++;

    }

}

/* Adds C * COEF * VAL to R.  VAL may be NULL, in that case only

   C * COEF is added to R.  */

static void

aff_combination_add_product (aff_tree *c, double_int coef, tree val,

                             aff_tree *r)

{

  unsigned i;

  tree aval, type;

  for (i = 0; i < c->n; i++)

    {

      aval = c->elts[i].val;

      if (val)

        {

          type = TREE_TYPE (aval);

          aval = fold_build2 (MULT_EXPR, type, aval,

                              fold_convert (type, val));

        }

      aff_combination_add_elt (r, aval,

                               double_int_mul (coef, c->elts[i].coef));

    }

  if (c->rest)

    {

      aval = c->rest;

      if (val)

        {

          type = TREE_TYPE (aval);

          aval = fold_build2 (MULT_EXPR, type, aval,

                              fold_convert (type, val));

        }

      aff_combination_add_elt (r, aval, coef);

    }

  if (val)

    aff_combination_add_elt (r, val,

                             double_int_mul (coef, c->offset));

  else

    aff_combination_add_cst (r, double_int_mul (coef, c->offset));

}

/* Multiplies C1 by C2, storing the result to R  */

void

aff_combination_mult (aff_tree *c1, aff_tree *c2, aff_tree *r)

{

  unsigned i;

  gcc_assert (TYPE_PRECISION (c1->type) == TYPE_PRECISION (c2->type));

  aff_combination_zero (r, c1->type);

  for (i = 0; i < c2->n; i++)

    aff_combination_add_product (c1, c2->elts[i].coef, c2->elts[i].val, r);

  if (c2->rest)

    aff_combination_add_product (c1, double_int_one, c2->rest, r);

  aff_combination_add_product (c1, c2->offset, NULL, r);

}

/* Returns the element of COMB whose value is VAL, or NULL if no such

   element exists.  If IDX is not NULL, it is set to the index of VAL in

   COMB.  */

static struct aff_comb_elt *

aff_combination_find_elt (aff_tree *comb, tree val, unsigned *idx)

{

  unsigned i;

  for (i = 0; i < comb->n; i++)

    if (operand_equal_p (comb->elts[i].val, val, 0))

      {

        if (idx)

          *idx = i;

        return &comb->elts[i];

      }

  return NULL;

}

/* Element of the cache that maps ssa name NAME to its expanded form

   as an affine expression EXPANSION.  */

struct name_expansion

{

  aff_tree expansion;

  /* True if the expansion for the name is just being generated.  */

  unsigned in_progress : 1;

};

/* Expands SSA names in COMB recursively.  CACHE is used to cache the

   results.  */

void

aff_combination_expand (aff_tree *comb ATTRIBUTE_UNUSED,

                        struct pointer_map_t **cache ATTRIBUTE_UNUSED)

{

  unsigned i;

  aff_tree to_add, current, curre;

  tree e, rhs;

  gimple def;

  double_int scale;

  void **slot;

  struct name_expansion *exp;

  aff_combination_zero (&to_add, comb->type);

  for (i = 0; i < comb->n; i++)

    {

      tree type, name;

      enum tree_code code;

      e = comb->elts[i].val;

      type = TREE_TYPE (e);

      name = e;

      /* Look through some conversions.  */

      if (TREE_CODE (e) == NOP_EXPR

          && (TYPE_PRECISION (type)

              >= TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (e, 0)))))

        name = TREE_OPERAND (e, 0);

      if (TREE_CODE (name) != SSA_NAME)

        continue;

      def = SSA_NAME_DEF_STMT (name);

      if (!is_gimple_assign (def) || gimple_assign_lhs (def) != name)

        continue;

      code = gimple_assign_rhs_code (def);

      if (code != SSA_NAME

          && !IS_EXPR_CODE_CLASS (TREE_CODE_CLASS (code))

          && (get_gimple_rhs_class (code) != GIMPLE_SINGLE_RHS

              || !is_gimple_min_invariant (gimple_assign_rhs1 (def))))

        continue;

      /* We do not know whether the reference retains its value at the

         place where the expansion is used.  */

      if (TREE_CODE_CLASS (code) == tcc_reference)

        continue;

      if (!*cache)

        *cache = pointer_map_create ();

      slot = pointer_map_insert (*cache, e);

      exp = (struct name_expansion *) *slot;

      if (!exp)

        {

          exp = XNEW (struct name_expansion);

          exp->in_progress = 1;

          *slot = exp;

          /* In principle this is a generally valid folding, but

             it is not unconditionally an optimization, so do it

             here and not in fold_unary.  */

          /* Convert (T1)(X *+- CST) into (T1)X *+- (T1)CST if T1 is wider

             than the type of X and overflow for the type of X is

             undefined.  */

          if (e != name

              && INTEGRAL_TYPE_P (type)

              && INTEGRAL_TYPE_P (TREE_TYPE (name))

              && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (name))

              && TYPE_PRECISION (type) > TYPE_PRECISION (TREE_TYPE (name))

              && (code == PLUS_EXPR || code == MINUS_EXPR || code == MULT_EXPR)

              && TREE_CODE (gimple_assign_rhs2 (def)) == INTEGER_CST)

            rhs = fold_build2 (code, type,

                               fold_convert (type, gimple_assign_rhs1 (def)),

                               fold_convert (type, gimple_assign_rhs2 (def)));

          else

            {

              rhs = gimple_assign_rhs_to_tree (def);

              if (e != name)

                rhs = fold_convert (type, rhs);

            }

          tree_to_aff_combination_expand (rhs, comb->type, &current, cache);

          exp->expansion = current;

          exp->in_progress = 0;

        }

      else

        {

          /* Since we follow the definitions in the SSA form, we should not

             enter a cycle unless we pass through a phi node.  */

          gcc_assert (!exp->in_progress);

          current = exp->expansion;

        }

      /* Accumulate the new terms to TO_ADD, so that we do not modify

         COMB while traversing it; include the term -coef * E, to remove

         it from COMB.  */

      scale = comb->elts[i].coef;

      aff_combination_zero (&curre, comb->type);

      aff_combination_add_elt (&curre, e, double_int_neg (scale));

      aff_combination_scale (&current, scale);

      aff_combination_add (&to_add, &current);

      aff_combination_add (&to_add, &curre);