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/* Memory address lowering and addressing mode selection.

   Copyright (C) 2004, 2006, 2007, 2008, 2009, 2010

   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/>.  */

/* Utility functions for manipulation with TARGET_MEM_REFs -- tree expressions

   that directly map to addressing modes of the target.  */

#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 "basic-block.h"

#include "output.h"

#include "diagnostic.h"

#include "tree-flow.h"

#include "tree-dump.h"

#include "tree-pass.h"

#include "timevar.h"

#include "flags.h"

#include "tree-inline.h"

#include "insn-config.h"

#include "recog.h"

#include "expr.h"

#include "ggc.h"

#include "tree-affine.h"

#include "target.h"

/* TODO -- handling of symbols (according to Richard Hendersons

   comments, http://gcc.gnu.org/ml/gcc-patches/2005-04/msg00949.html):

   There are at least 5 different kinds of symbols that we can run up against:

     (1) binds_local_p, small data area.

     (2) binds_local_p, eg local statics

     (3) !binds_local_p, eg global variables

     (4) thread local, local_exec

     (5) thread local, !local_exec

   Now, (1) won't appear often in an array context, but it certainly can.

   All you have to do is set -GN high enough, or explicitly mark any

   random object __attribute__((section (".sdata"))).

   All of these affect whether or not a symbol is in fact a valid address.

   The only one tested here is (3).  And that result may very well

   be incorrect for (4) or (5).

   An incorrect result here does not cause incorrect results out the

   back end, because the expander in expr.c validizes the address.  However

   it would be nice to improve the handling here in order to produce more

   precise results.  */

/* A "template" for memory address, used to determine whether the address is

   valid for mode.  */

typedef struct GTY (()) mem_addr_template {

  rtx ref;                      /* The template.  */

  rtx * GTY ((skip)) step_p;    /* The point in template where the step should be

                                   filled in.  */

  rtx * GTY ((skip)) off_p;     /* The point in template where the offset should

                                   be filled in.  */

} mem_addr_template;

DEF_VEC_O (mem_addr_template);

DEF_VEC_ALLOC_O (mem_addr_template, gc);

/* The templates.  Each of the low five bits of the index corresponds to one

   component of TARGET_MEM_REF being present, while the high bits identify

   the address space.  See TEMPL_IDX.  */

static GTY(()) VEC (mem_addr_template, gc) *mem_addr_template_list;

#define TEMPL_IDX(AS, SYMBOL, BASE, INDEX, STEP, OFFSET) \

  (((int) (AS) << 5) \

   | ((SYMBOL != 0) << 4) \

   | ((BASE != 0) << 3) \

   | ((INDEX != 0) << 2) \

   | ((STEP != 0) << 1) \

   | (OFFSET != 0))

/* Stores address for memory reference with parameters SYMBOL, BASE, INDEX,

   STEP and OFFSET to *ADDR using address mode ADDRESS_MODE.  Stores pointers

   to where step is placed to *STEP_P and offset to *OFFSET_P.  */

static void

gen_addr_rtx (enum machine_mode address_mode,

              rtx symbol, rtx base, rtx index, rtx step, rtx offset,

              rtx *addr, rtx **step_p, rtx **offset_p)

{

  rtx act_elem;

  *addr = NULL_RTX;

  if (step_p)

    *step_p = NULL;

  if (offset_p)

    *offset_p = NULL;

  if (index)

    {

      act_elem = index;

      if (step)

        {

          act_elem = gen_rtx_MULT (address_mode, act_elem, step);

          if (step_p)

            *step_p = &XEXP (act_elem, 1);

        }

      *addr = act_elem;

    }

  if (base)

    {

      if (*addr)

        *addr = simplify_gen_binary (PLUS, address_mode, base, *addr);

      else

        *addr = base;

    }

  if (symbol)

    {

      act_elem = symbol;

      if (offset)

        {

          act_elem = gen_rtx_PLUS (address_mode, act_elem, offset);

          if (offset_p)

            *offset_p = &XEXP (act_elem, 1);

          if (GET_CODE (symbol) == SYMBOL_REF

              || GET_CODE (symbol) == LABEL_REF

              || GET_CODE (symbol) == CONST)

            act_elem = gen_rtx_CONST (address_mode, act_elem);

        }

      if (*addr)

        *addr = gen_rtx_PLUS (address_mode, *addr, act_elem);

      else

        *addr = act_elem;

    }

  else if (offset)

    {

      if (*addr)

        {

          *addr = gen_rtx_PLUS (address_mode, *addr, offset);

          if (offset_p)

            *offset_p = &XEXP (*addr, 1);

        }

      else

        {

          *addr = offset;

          if (offset_p)

            *offset_p = addr;

        }

    }

  if (!*addr)

    *addr = const0_rtx;

}

/* Returns address for TARGET_MEM_REF with parameters given by ADDR

   in address space AS.

   If REALLY_EXPAND is false, just make fake registers instead

   of really expanding the operands, and perform the expansion in-place

   by using one of the "templates".  */

rtx

addr_for_mem_ref (struct mem_address *addr, addr_space_t as,

                  bool really_expand)

{

  enum machine_mode address_mode = targetm.addr_space.address_mode (as);

  rtx address, sym, bse, idx, st, off;

  struct mem_addr_template *templ;

  if (addr->step && !integer_onep (addr->step))

    st = immed_double_const (TREE_INT_CST_LOW (addr->step),

                             TREE_INT_CST_HIGH (addr->step), address_mode);

  else

    st = NULL_RTX;

  if (addr->offset && !integer_zerop (addr->offset))

    off = immed_double_const (TREE_INT_CST_LOW (addr->offset),

                              TREE_INT_CST_HIGH (addr->offset), address_mode);

  else

    off = NULL_RTX;

  if (!really_expand)

    {

      unsigned int templ_index

        = TEMPL_IDX (as, addr->symbol, addr->base, addr->index, st, off);

      if (templ_index

          >= VEC_length (mem_addr_template, mem_addr_template_list))

        VEC_safe_grow_cleared (mem_addr_template, gc, mem_addr_template_list,

                               templ_index + 1);

      /* Reuse the templates for addresses, so that we do not waste memory.  */

      templ = VEC_index (mem_addr_template, mem_addr_template_list, templ_index);

      if (!templ->ref)

        {

          sym = (addr->symbol ?

                 gen_rtx_SYMBOL_REF (address_mode, ggc_strdup ("test_symbol"))

                 : NULL_RTX);

          bse = (addr->base ?

                 gen_raw_REG (address_mode, LAST_VIRTUAL_REGISTER + 1)

                 : NULL_RTX);

          idx = (addr->index ?

                 gen_raw_REG (address_mode, LAST_VIRTUAL_REGISTER + 2)

                 : NULL_RTX);

          gen_addr_rtx (address_mode, sym, bse, idx,

                        st? const0_rtx : NULL_RTX,

                        off? const0_rtx : NULL_RTX,

                        &templ->ref,

                        &templ->step_p,

                        &templ->off_p);

        }

      if (st)

        *templ->step_p = st;

      if (off)

        *templ->off_p = off;

      return templ->ref;

    }

  /* Otherwise really expand the expressions.  */

  sym = (addr->symbol

         ? expand_expr (build_addr (addr->symbol, current_function_decl),

                        NULL_RTX, address_mode, EXPAND_NORMAL)

         : NULL_RTX);

  bse = (addr->base

         ? expand_expr (addr->base, NULL_RTX, address_mode, EXPAND_NORMAL)

         : NULL_RTX);

  idx = (addr->index

         ? expand_expr (addr->index, NULL_RTX, address_mode, EXPAND_NORMAL)

         : NULL_RTX);

  gen_addr_rtx (address_mode, sym, bse, idx, st, off, &address, NULL, NULL);

  return address;

}

/* Returns address of MEM_REF in TYPE.  */

tree

tree_mem_ref_addr (tree type, tree mem_ref)

{

  tree addr;

  tree act_elem;

  tree step = TMR_STEP (mem_ref), offset = TMR_OFFSET (mem_ref);

  tree sym = TMR_SYMBOL (mem_ref), base = TMR_BASE (mem_ref);

  tree addr_base = NULL_TREE, addr_off = NULL_TREE;

  if (sym)

    addr_base = fold_convert (type, build_addr (sym, current_function_decl));

  else if (base && POINTER_TYPE_P (TREE_TYPE (base)))

    {

      addr_base = fold_convert (type, base);

      base = NULL_TREE;

    }

  act_elem = TMR_INDEX (mem_ref);

  if (act_elem)

    {

      if (step)

        act_elem = fold_build2 (MULT_EXPR, sizetype, act_elem, step);

      addr_off = act_elem;

    }

  act_elem = base;

  if (act_elem)

    {

      if (addr_off)

        addr_off = fold_build2 (PLUS_EXPR, sizetype, addr_off, act_elem);

      else

        addr_off = act_elem;

    }

  if (offset && !integer_zerop (offset))

    {

      if (addr_off)

        addr_off = fold_build2 (PLUS_EXPR, sizetype, addr_off, offset);

      else

        addr_off = offset;

    }

  if (addr_off)

    {

      if (addr_base)

        addr = fold_build2 (POINTER_PLUS_EXPR, type, addr_base, addr_off);

      else

        addr = fold_convert (type, addr_off);

    }

  else if (addr_base)

    addr = addr_base;

  else

    addr = build_int_cst (type, 0);

  return addr;

}

/* Returns true if a memory reference in MODE and with parameters given by

   ADDR is valid on the current target.  */

static bool

valid_mem_ref_p (enum machine_mode mode, addr_space_t as,

                 struct mem_address *addr)

{

  rtx address;

  address = addr_for_mem_ref (addr, as, false);

  if (!address)

    return false;

  return memory_address_addr_space_p (mode, address, as);

}

/* Checks whether a TARGET_MEM_REF with type TYPE and parameters given by ADDR

   is valid on the current target and if so, creates and returns the

   TARGET_MEM_REF.  */

static tree

create_mem_ref_raw (tree type, struct mem_address *addr)

{

  if (!valid_mem_ref_p (TYPE_MODE (type), TYPE_ADDR_SPACE (type), addr))

    return NULL_TREE;

  if (addr->step && integer_onep (addr->step))

    addr->step = NULL_TREE;

  if (addr->offset && integer_zerop (addr->offset))

    addr->offset = NULL_TREE;

  return build6 (TARGET_MEM_REF, type,

                 addr->symbol, addr->base, addr->index,

                 addr->step, addr->offset, NULL);

}

/* Returns true if OBJ is an object whose address is a link time constant.  */

static bool

fixed_address_object_p (tree obj)

{

  return (TREE_CODE (obj) == VAR_DECL

          && (TREE_STATIC (obj)

              || DECL_EXTERNAL (obj))

          && ! DECL_DLLIMPORT_P (obj));

}

/* If ADDR contains an address of object that is a link time constant,

   move it to PARTS->symbol.  */

static void

move_fixed_address_to_symbol (struct mem_address *parts, aff_tree *addr)

{

  unsigned i;

  tree val = NULL_TREE;

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

    {

      if (!double_int_one_p (addr->elts[i].coef))

        continue;

      val = addr->elts[i].val;

      if (TREE_CODE (val) == ADDR_EXPR

          && fixed_address_object_p (TREE_OPERAND (val, 0)))

        break;

    }

  if (i == addr->n)

    return;

  parts->symbol = TREE_OPERAND (val, 0);

  aff_combination_remove_elt (addr, i);

}

/* If ADDR contains an instance of BASE_HINT, move it to PARTS->base.  */

static void

move_hint_to_base (tree type, struct mem_address *parts, tree base_hint,

                   aff_tree *addr)

{

  unsigned i;

  tree val = NULL_TREE;

  int qual;

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

    {

      if (!double_int_one_p (addr->elts[i].coef))

        continue;

      val = addr->elts[i].val;

      if (operand_equal_p (val, base_hint, 0))

        break;

    }

  if (i == addr->n)

    return;

  /* Cast value to appropriate pointer type.  We cannot use a pointer

     to TYPE directly, as the back-end will assume registers of pointer

     type are aligned, and just the base itself may not actually be.

     We use void pointer to the type's address space instead.  */

  qual = ENCODE_QUAL_ADDR_SPACE (TYPE_ADDR_SPACE (type));

  type = build_qualified_type (void_type_node, qual);

  parts->base = fold_convert (build_pointer_type (type), val);

  aff_combination_remove_elt (addr, i);

}

/* If ADDR contains an address of a dereferenced pointer, move it to

   PARTS->base.  */

static void

move_pointer_to_base (struct mem_address *parts, aff_tree *addr)

{

  unsigned i;

  tree val = NULL_TREE;

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

    {

      if (!double_int_one_p (addr->elts[i].coef))

        continue;

      val = addr->elts[i].val;

      if (POINTER_TYPE_P (TREE_TYPE (val)))

        break;

    }

  if (i == addr->n)

    return;

  parts->base = val;

  aff_combination_remove_elt (addr, i);

}

/* Adds ELT to PARTS.  */

static void

add_to_parts (struct mem_address *parts, tree elt)

{

  tree type;

  if (!parts->index)

    {

      parts->index = fold_convert (sizetype, elt);

      return;

    }

  if (!parts->base)

    {

      parts->base = elt;

      return;

    }

  /* Add ELT to base.  */

  type = TREE_TYPE (parts->base);

  if (POINTER_TYPE_P (type))

    parts->base = fold_build2 (POINTER_PLUS_EXPR, type,

                               parts->base,

                               fold_convert (sizetype, elt));

  else

    parts->base = fold_build2 (PLUS_EXPR, type,

                               parts->base, elt);

}

/* Finds the most expensive multiplication in ADDR that can be

   expressed in an addressing mode and move the corresponding

   element(s) to PARTS.  */

static void

most_expensive_mult_to_index (tree type, struct mem_address *parts,

                              aff_tree *addr, bool speed)

{

  addr_space_t as = TYPE_ADDR_SPACE (type);

  enum machine_mode address_mode = targetm.addr_space.address_mode (as);

  HOST_WIDE_INT coef;

  double_int best_mult, amult, amult_neg;

  unsigned best_mult_cost = 0, acost;

  tree mult_elt = NULL_TREE, elt;

  unsigned i, j;

  enum tree_code op_code;

  best_mult = double_int_zero;

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

    {

      if (!double_int_fits_in_shwi_p (addr->elts[i].coef))

        continue;

      coef = double_int_to_shwi (addr->elts[i].coef);

      if (coef == 1

          || !multiplier_allowed_in_address_p (coef, TYPE_MODE (type), as))

        continue;

      acost = multiply_by_cost (coef, address_mode, speed);

      if (acost > best_mult_cost)

        {

          best_mult_cost = acost;

          best_mult = addr->elts[i].coef;

        }

    }

  if (!best_mult_cost)

    return;

  /* Collect elements multiplied by best_mult.  */

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

    {

      amult = addr->elts[i].coef;

      amult_neg = double_int_ext_for_comb (double_int_neg (amult), addr);

      if (double_int_equal_p (amult, best_mult))

        op_code = PLUS_EXPR;

      else if (double_int_equal_p (amult_neg, best_mult))

        op_code = MINUS_EXPR;

      else

        {

          addr->elts[j] = addr->elts[i];

          j++;

          continue;

        }

      elt = fold_convert (sizetype, addr->elts[i].val);

      if (mult_elt)

        mult_elt = fold_build2 (op_code, sizetype, mult_elt, elt);

      else if (op_code == PLUS_EXPR)

        mult_elt = elt;

      else

        mult_elt = fold_build1 (NEGATE_EXPR, sizetype, elt);

    }

  addr->n = j;

  parts->index = mult_elt;

  parts->step = double_int_to_tree (sizetype, best_mult);

}

/* Splits address ADDR for a memory access of type TYPE into PARTS.

   If BASE_HINT is non-NULL, it specifies an SSA name to be used

   preferentially as base of the reference.

   TODO -- be more clever about the distribution of the elements of ADDR

   to PARTS.  Some architectures do not support anything but single

   register in address, possibly with a small integer offset; while

   create_mem_ref will simplify the address to an acceptable shape

   later, it would be more efficient to know that asking for complicated

   addressing modes is useless.  */

static void

addr_to_parts (tree type, aff_tree *addr, tree base_hint,

               struct mem_address *parts, bool speed)

{

  tree part;

  unsigned i;

  parts->symbol = NULL_TREE;

  parts->base = NULL_TREE;

  parts->index = NULL_TREE;

  parts->step = NULL_TREE;

  if (!double_int_zero_p (addr->offset))

    parts->offset = double_int_to_tree (sizetype, addr->offset);

  else

    parts->offset = NULL_TREE;

  /* Try to find a symbol.  */

  move_fixed_address_to_symbol (parts, addr);

  /* First move the most expensive feasible multiplication

     to index.  */

  most_expensive_mult_to_index (type, parts, addr, speed);

  /* Try to find a base of the reference.  Since at the moment

     there is no reliable way how to distinguish between pointer and its

     offset, this is just a guess.  */

  if (!parts->symbol && base_hint)

    move_hint_to_base (type, parts, base_hint, addr);

  if (!parts->symbol && !parts->base)

    move_pointer_to_base (parts, addr);

  /* Then try to process the remaining elements.  */

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

    {

      part = fold_convert (sizetype, addr->elts[i].val);

      if (!double_int_one_p (addr->elts[i].coef))

        part = fold_build2 (MULT_EXPR, sizetype, part,

                            double_int_to_tree (sizetype, addr->elts[i].coef));

      add_to_parts (parts, part);

    }

  if (addr->rest)

    add_to_parts (parts, fold_convert (sizetype, addr->rest));

}

/* Force the PARTS to register.  */

static void

gimplify_mem_ref_parts (gimple_stmt_iterator *gsi, struct mem_address *parts)

{

  if (parts->base)

    parts->base = force_gimple_operand_gsi (gsi, parts->base,

                                            true, NULL_TREE,

                                            true, GSI_SAME_STMT);

  if (parts->index)

    parts->index = force_gimple_operand_gsi (gsi, parts->index,

                                             true, NULL_TREE,

                                             true, GSI_SAME_STMT);

}

/* Creates and returns a TARGET_MEM_REF for address ADDR.  If necessary

   computations are emitted in front of GSI.  TYPE is the mode

   of created memory reference.  */

tree

create_mem_ref (gimple_stmt_iterator *gsi, tree type, aff_tree *addr,

                tree base_hint, bool speed)

{

  tree mem_ref, tmp;

  tree atype;

  struct mem_address parts;

  addr_to_parts (type, addr, base_hint, &parts, speed);

  gimplify_mem_ref_parts (gsi, &parts);

  mem_ref = create_mem_ref_raw (type, &parts);

  if (mem_ref)

    return mem_ref;

  /* The expression is too complicated.  Try making it simpler.  */

  if (parts.step && !integer_onep (parts.step))

    {

      /* Move the multiplication to index.  */

      gcc_assert (parts.index);

      parts.index = force_gimple_operand_gsi (gsi,

                                fold_build2 (MULT_EXPR, sizetype,

                                             parts.index, parts.step),

                                true, NULL_TREE, true, GSI_SAME_STMT);

      parts.step = NULL_TREE;

      mem_ref = create_mem_ref_raw (type, &parts);

      if (mem_ref)

        return mem_ref;

    }

  if (parts.symbol)

    {

      tmp = build_addr (parts.symbol, current_function_decl);

      gcc_assert (is_gimple_val (tmp));

      /* Add the symbol to base, eventually forcing it to register.  */

      if (parts.base)

        {

          gcc_assert (useless_type_conversion_p

                                (sizetype, TREE_TYPE (parts.base)));

          if (parts.index)

            {

              atype = TREE_TYPE (tmp);

              parts.base = force_gimple_operand_gsi (gsi,

                        fold_build2 (POINTER_PLUS_EXPR, atype,

                                     tmp,

                                     fold_convert (sizetype, parts.base)),

                        true, NULL_TREE, true, GSI_SAME_STMT);

            }

          else

            {

              parts.index = parts.base;

              parts.base = tmp;

            }

        }

      else

        parts.base = tmp;

      parts.symbol = NULL_TREE;