Subversion Repositories scarts

/* Lower vector operations to scalar operations.

   Copyright (C) 2004, 2005 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 2, 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 COPYING.  If not, write to the Free

Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301, USA.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tree.h"

#include "tm.h"

#include "rtl.h"

#include "expr.h"

#include "insn-codes.h"

#include "diagnostic.h"

#include "optabs.h"

#include "machmode.h"

#include "langhooks.h"

#include "tree-flow.h"

#include "tree-gimple.h"

#include "tree-iterator.h"

#include "tree-pass.h"

#include "flags.h"

#include "ggc.h"

/* Build a constant of type TYPE, made of VALUE's bits replicated

   every TYPE_SIZE (INNER_TYPE) bits to fit TYPE's precision.  */

static tree

build_replicated_const (tree type, tree inner_type, HOST_WIDE_INT value)

{

  int width = tree_low_cst (TYPE_SIZE (inner_type), 1);

  int n = HOST_BITS_PER_WIDE_INT / width;

  unsigned HOST_WIDE_INT low, high, mask;

  tree ret;

  gcc_assert (n);

  if (width == HOST_BITS_PER_WIDE_INT)

    low = value;

  else

    {

      mask = ((HOST_WIDE_INT)1 << width) - 1;

      low = (unsigned HOST_WIDE_INT) ~0 / mask * (value & mask);

    }

  if (TYPE_PRECISION (type) < HOST_BITS_PER_WIDE_INT)

    low &= ((HOST_WIDE_INT)1 << TYPE_PRECISION (type)) - 1, high = 0;

  else if (TYPE_PRECISION (type) == HOST_BITS_PER_WIDE_INT)

    high = 0;

  else if (TYPE_PRECISION (type) == 2 * HOST_BITS_PER_WIDE_INT)

    high = low;

  else

    gcc_unreachable ();

  ret = build_int_cst_wide (type, low, high);

  return ret;

}

static GTY(()) tree vector_inner_type;

static GTY(()) tree vector_last_type;

static GTY(()) int vector_last_nunits;

/* Return a suitable vector types made of SUBPARTS units each of mode

   "word_mode" (the global variable).  */

static tree

build_word_mode_vector_type (int nunits)

{

  if (!vector_inner_type)

    vector_inner_type = lang_hooks.types.type_for_mode (word_mode, 1);

  else if (vector_last_nunits == nunits)

    {

      gcc_assert (TREE_CODE (vector_last_type) == VECTOR_TYPE);

      return vector_last_type;

    }

  /* We build a new type, but we canonicalize it nevertheless,

     because it still saves some memory.  */

  vector_last_nunits = nunits;

  vector_last_type = type_hash_canon (nunits,

                                      build_vector_type (vector_inner_type,

                                                         nunits));

  return vector_last_type;

}

typedef tree (*elem_op_func) (block_stmt_iterator *,

                              tree, tree, tree, tree, tree, enum tree_code);

static inline tree

tree_vec_extract (block_stmt_iterator *bsi, tree type,

                  tree t, tree bitsize, tree bitpos)

{

  if (bitpos)

    return gimplify_build3 (bsi, BIT_FIELD_REF, type, t, bitsize, bitpos);

  else

    return gimplify_build1 (bsi, VIEW_CONVERT_EXPR, type, t);

}

static tree

do_unop (block_stmt_iterator *bsi, tree inner_type, tree a,

         tree b ATTRIBUTE_UNUSED, tree bitpos, tree bitsize,

         enum tree_code code)

{

  a = tree_vec_extract (bsi, inner_type, a, bitsize, bitpos);

  return gimplify_build1 (bsi, code, inner_type, a);

}

static tree

do_binop (block_stmt_iterator *bsi, tree inner_type, tree a, tree b,

          tree bitpos, tree bitsize, enum tree_code code)

{

  a = tree_vec_extract (bsi, inner_type, a, bitsize, bitpos);

  b = tree_vec_extract (bsi, inner_type, b, bitsize, bitpos);

  return gimplify_build2 (bsi, code, inner_type, a, b);

}

/* Expand vector addition to scalars.  This does bit twiddling

   in order to increase parallelism:

   a + b = (((int) a & 0x7f7f7f7f) + ((int) b & 0x7f7f7f7f)) ^

           (a ^ b) & 0x80808080

   a - b =  (((int) a | 0x80808080) - ((int) b & 0x7f7f7f7f)) ^

            (a ^ ~b) & 0x80808080

   -b = (0x80808080 - ((int) b & 0x7f7f7f7f)) ^ (~b & 0x80808080)

   This optimization should be done only if 4 vector items or more

   fit into a word.  */

static tree

do_plus_minus (block_stmt_iterator *bsi, tree word_type, tree a, tree b,

               tree bitpos ATTRIBUTE_UNUSED, tree bitsize ATTRIBUTE_UNUSED,

               enum tree_code code)

{

  tree inner_type = TREE_TYPE (TREE_TYPE (a));

  unsigned HOST_WIDE_INT max;

  tree low_bits, high_bits, a_low, b_low, result_low, signs;

  max = GET_MODE_MASK (TYPE_MODE (inner_type));

  low_bits = build_replicated_const (word_type, inner_type, max >> 1);

  high_bits = build_replicated_const (word_type, inner_type, max & ~(max >> 1));

  a = tree_vec_extract (bsi, word_type, a, bitsize, bitpos);

  b = tree_vec_extract (bsi, word_type, b, bitsize, bitpos);

  signs = gimplify_build2 (bsi, BIT_XOR_EXPR, word_type, a, b);

  b_low = gimplify_build2 (bsi, BIT_AND_EXPR, word_type, b, low_bits);

  if (code == PLUS_EXPR)

    a_low = gimplify_build2 (bsi, BIT_AND_EXPR, word_type, a, low_bits);

  else

    {

      a_low = gimplify_build2 (bsi, BIT_IOR_EXPR, word_type, a, high_bits);

      signs = gimplify_build1 (bsi, BIT_NOT_EXPR, word_type, signs);

    }

  signs = gimplify_build2 (bsi, BIT_AND_EXPR, word_type, signs, high_bits);

  result_low = gimplify_build2 (bsi, code, word_type, a_low, b_low);

  return gimplify_build2 (bsi, BIT_XOR_EXPR, word_type, result_low, signs);

}

static tree

do_negate (block_stmt_iterator *bsi, tree word_type, tree b,

           tree unused ATTRIBUTE_UNUSED, tree bitpos ATTRIBUTE_UNUSED,

           tree bitsize ATTRIBUTE_UNUSED,

           enum tree_code code ATTRIBUTE_UNUSED)

{

  tree inner_type = TREE_TYPE (TREE_TYPE (b));

  HOST_WIDE_INT max;

  tree low_bits, high_bits, b_low, result_low, signs;

  max = GET_MODE_MASK (TYPE_MODE (inner_type));

  low_bits = build_replicated_const (word_type, inner_type, max >> 1);

  high_bits = build_replicated_const (word_type, inner_type, max & ~(max >> 1));

  b = tree_vec_extract (bsi, word_type, b, bitsize, bitpos);

  b_low = gimplify_build2 (bsi, BIT_AND_EXPR, word_type, b, low_bits);

  signs = gimplify_build1 (bsi, BIT_NOT_EXPR, word_type, b);

  signs = gimplify_build2 (bsi, BIT_AND_EXPR, word_type, signs, high_bits);

  result_low = gimplify_build2 (bsi, MINUS_EXPR, word_type, high_bits, b_low);

  return gimplify_build2 (bsi, BIT_XOR_EXPR, word_type, result_low, signs);

}

/* Expand a vector operation to scalars, by using many operations

   whose type is the vector type's inner type.  */

static tree

expand_vector_piecewise (block_stmt_iterator *bsi, elem_op_func f,

                         tree type, tree inner_type,

                         tree a, tree b, enum tree_code code)

{

  VEC(constructor_elt,gc) *v;

  tree part_width = TYPE_SIZE (inner_type);

  tree index = bitsize_int (0);

  int nunits = TYPE_VECTOR_SUBPARTS (type);

  int delta = tree_low_cst (part_width, 1)

              / tree_low_cst (TYPE_SIZE (TREE_TYPE (type)), 1);

  int i;

  v = VEC_alloc(constructor_elt, gc, (nunits + delta - 1) / delta);

  for (i = 0; i < nunits;

       i += delta, index = int_const_binop (PLUS_EXPR, index, part_width, 0))

    {

      tree result = f (bsi, inner_type, a, b, index, part_width, code);

      constructor_elt *ce = VEC_quick_push (constructor_elt, v, NULL);

      ce->index = NULL_TREE;

      ce->value = result;

    }

  return build_constructor (type, v);

}

/* Expand a vector operation to scalars with the freedom to use

   a scalar integer type, or to use a different size for the items

   in the vector type.  */

static tree

expand_vector_parallel (block_stmt_iterator *bsi, elem_op_func f, tree type,

                        tree a, tree b,

                        enum tree_code code)

{

  tree result, compute_type;

  enum machine_mode mode;

  int n_words = tree_low_cst (TYPE_SIZE_UNIT (type), 1) / UNITS_PER_WORD;

  /* We have three strategies.  If the type is already correct, just do

     the operation an element at a time.  Else, if the vector is wider than

     one word, do it a word at a time; finally, if the vector is smaller

     than one word, do it as a scalar.  */

  if (TYPE_MODE (TREE_TYPE (type)) == word_mode)

     return expand_vector_piecewise (bsi, f,

                                     type, TREE_TYPE (type),

                                     a, b, code);

  else if (n_words > 1)

    {

      tree word_type = build_word_mode_vector_type (n_words);

      result = expand_vector_piecewise (bsi, f,

                                        word_type, TREE_TYPE (word_type),

                                        a, b, code);

      result = gimplify_val (bsi, word_type, result);

    }

  else

    {

      /* Use a single scalar operation with a mode no wider than word_mode.  */

      mode = mode_for_size (tree_low_cst (TYPE_SIZE (type), 1), MODE_INT, 0);

      compute_type = lang_hooks.types.type_for_mode (mode, 1);

      result = f (bsi, compute_type, a, b, NULL_TREE, NULL_TREE, code);

    }

  return result;

}

/* Expand a vector operation to scalars; for integer types we can use

   special bit twiddling tricks to do the sums a word at a time, using

   function F_PARALLEL instead of F.  These tricks are done only if

   they can process at least four items, that is, only if the vector

   holds at least four items and if a word can hold four items.  */

static tree

expand_vector_addition (block_stmt_iterator *bsi,

                        elem_op_func f, elem_op_func f_parallel,

                        tree type, tree a, tree b, enum tree_code code)

{

  int parts_per_word = UNITS_PER_WORD

                       / tree_low_cst (TYPE_SIZE_UNIT (TREE_TYPE (type)), 1);

  if (INTEGRAL_TYPE_P (TREE_TYPE (type))

      && parts_per_word >= 4

      && TYPE_VECTOR_SUBPARTS (type) >= 4)

    return expand_vector_parallel (bsi, f_parallel,

                                   type, a, b, code);

  else

    return expand_vector_piecewise (bsi, f,

                                    type, TREE_TYPE (type),

                                    a, b, code);

}

static tree

expand_vector_operation (block_stmt_iterator *bsi, tree type, tree compute_type,

                         tree rhs, enum tree_code code)

{

  enum machine_mode compute_mode = TYPE_MODE (compute_type);

  /* If the compute mode is not a vector mode (hence we are not decomposing

     a BLKmode vector to smaller, hardware-supported vectors), we may want

     to expand the operations in parallel.  */

  if (GET_MODE_CLASS (compute_mode) != MODE_VECTOR_INT

      && GET_MODE_CLASS (compute_mode) != MODE_VECTOR_FLOAT)

    switch (code)

      {

      case PLUS_EXPR:

      case MINUS_EXPR:

        if (!TYPE_TRAP_SIGNED (type))

          return expand_vector_addition (bsi, do_binop, do_plus_minus, type,

                                         TREE_OPERAND (rhs, 0),

                                         TREE_OPERAND (rhs, 1), code);

        break;

      case NEGATE_EXPR:

        if (!TYPE_TRAP_SIGNED (type))

          return expand_vector_addition (bsi, do_unop, do_negate, type,

                                         TREE_OPERAND (rhs, 0),

                                         NULL_TREE, code);

        break;

      case BIT_AND_EXPR:

      case BIT_IOR_EXPR:

      case BIT_XOR_EXPR:

        return expand_vector_parallel (bsi, do_binop, type,

                                       TREE_OPERAND (rhs, 0),

                                       TREE_OPERAND (rhs, 1), code);

      case BIT_NOT_EXPR:

        return expand_vector_parallel (bsi, do_unop, type,

                                       TREE_OPERAND (rhs, 0),

                                       NULL_TREE, code);

      default:

        break;

      }

  if (TREE_CODE_CLASS (code) == tcc_unary)

    return expand_vector_piecewise (bsi, do_unop, type, compute_type,

                                    TREE_OPERAND (rhs, 0),

                                    NULL_TREE, code);

  else

    return expand_vector_piecewise (bsi, do_binop, type, compute_type,

                                    TREE_OPERAND (rhs, 0),

                                    TREE_OPERAND (rhs, 1), code);

}

/* Return a type for the widest vector mode whose components are of mode

   INNER_MODE, or NULL_TREE if none is found.  */

static tree

type_for_widest_vector_mode (enum machine_mode inner_mode, optab op)

{

  enum machine_mode best_mode = VOIDmode, mode;

  int best_nunits = 0;

  if (GET_MODE_CLASS (inner_mode) == MODE_FLOAT)

    mode = MIN_MODE_VECTOR_FLOAT;

  else

    mode = MIN_MODE_VECTOR_INT;

  for (; mode != VOIDmode; mode = GET_MODE_WIDER_MODE (mode))

    if (GET_MODE_INNER (mode) == inner_mode

        && GET_MODE_NUNITS (mode) > best_nunits

        && op->handlers[mode].insn_code != CODE_FOR_nothing)

      best_mode = mode, best_nunits = GET_MODE_NUNITS (mode);

  if (best_mode == VOIDmode)

    return NULL_TREE;

  else

    return lang_hooks.types.type_for_mode (best_mode, 1);

}

/* Process one statement.  If we identify a vector operation, expand it.  */

static void

expand_vector_operations_1 (block_stmt_iterator *bsi)

{

  tree stmt = bsi_stmt (*bsi);

  tree *p_lhs, *p_rhs, lhs, rhs, type, compute_type;

  enum tree_code code;

  enum machine_mode compute_mode;

  optab op;

  switch (TREE_CODE (stmt))

    {

    case RETURN_EXPR:

      stmt = TREE_OPERAND (stmt, 0);

      if (!stmt || TREE_CODE (stmt) != MODIFY_EXPR)

        return;

      /* FALLTHRU */

    case MODIFY_EXPR:

      p_lhs = &TREE_OPERAND (stmt, 0);

      p_rhs = &TREE_OPERAND (stmt, 1);

      lhs = *p_lhs;

      rhs = *p_rhs;

      break;

    default:

      return;

    }

  type = TREE_TYPE (rhs);

  if (TREE_CODE (type) != VECTOR_TYPE)

    return;

  code = TREE_CODE (rhs);

  if (TREE_CODE_CLASS (code) != tcc_unary

      && TREE_CODE_CLASS (code) != tcc_binary)

    return;

  if (code == NOP_EXPR || code == VIEW_CONVERT_EXPR)

    return;

  gcc_assert (code != CONVERT_EXPR);

  op = optab_for_tree_code (code, type);

  /* Optabs will try converting a negation into a subtraction, so

     look for it as well.  TODO: negation of floating-point vectors

     might be turned into an exclusive OR toggling the sign bit.  */

  if (op == NULL

      && code == NEGATE_EXPR

      && INTEGRAL_TYPE_P (TREE_TYPE (type)))

    op = optab_for_tree_code (MINUS_EXPR, type);

  /* For very wide vectors, try using a smaller vector mode.  */

  compute_type = type;

  if (TYPE_MODE (type) == BLKmode && op)

    {

      tree vector_compute_type

        = type_for_widest_vector_mode (TYPE_MODE (TREE_TYPE (type)), op);

      if (vector_compute_type != NULL_TREE)

        compute_type = vector_compute_type;

    }

  /* If we are breaking a BLKmode vector into smaller pieces,

     type_for_widest_vector_mode has already looked into the optab,

     so skip these checks.  */

  if (compute_type == type)

    {

      compute_mode = TYPE_MODE (compute_type);

      if ((GET_MODE_CLASS (compute_mode) == MODE_VECTOR_INT

           || GET_MODE_CLASS (compute_mode) == MODE_VECTOR_FLOAT)

          && op != NULL

          && op->handlers[compute_mode].insn_code != CODE_FOR_nothing)

        return;

      else

        /* There is no operation in hardware, so fall back to scalars.  */

        compute_type = TREE_TYPE (type);

    }

  gcc_assert (code != VEC_LSHIFT_EXPR && code != VEC_RSHIFT_EXPR);

  rhs = expand_vector_operation (bsi, type, compute_type, rhs, code);

  if (lang_hooks.types_compatible_p (TREE_TYPE (lhs), TREE_TYPE (rhs)))

    *p_rhs = rhs;

  else

    *p_rhs = gimplify_build1 (bsi, VIEW_CONVERT_EXPR, TREE_TYPE (lhs), rhs);

  mark_stmt_modified (bsi_stmt (*bsi));

}

/* Use this to lower vector operations introduced by the vectorizer,

   if it may need the bit-twiddling tricks implemented in this file.  */

static bool

gate_expand_vector_operations (void)

{

  return flag_tree_vectorize != 0;

}

static void

expand_vector_operations (void)

{

  block_stmt_iterator bsi;

  basic_block bb;

  FOR_EACH_BB (bb)

    {

      for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))

        {

          expand_vector_operations_1 (&bsi);

          update_stmt_if_modified (bsi_stmt (bsi));

        }

    }

}

struct tree_opt_pass pass_lower_vector =

{

  "veclower",                           /* name */

  0,                                     /* gate */

  expand_vector_operations,             /* execute */

  NULL,                                 /* sub */

  NULL,                                 /* next */

  0,                                     /* static_pass_number */

  0,                                     /* tv_id */

  PROP_cfg,                             /* properties_required */

  0,                                     /* properties_provided */

  0,                                     /* properties_destroyed */

  0,                                     /* todo_flags_start */

  TODO_dump_func | TODO_ggc_collect

    | TODO_verify_stmts,                /* todo_flags_finish */

};

struct tree_opt_pass pass_lower_vector_ssa =

{

  "veclower2",                          /* name */

  gate_expand_vector_operations,        /* gate */

  expand_vector_operations,             /* execute */

  NULL,                                 /* sub */

  NULL,                                 /* next */

  0,                                     /* static_pass_number */

  0,                                     /* tv_id */

  PROP_cfg,                             /* properties_required */

  0,                                     /* properties_provided */

  0,                                     /* properties_destroyed */

  0,                                     /* todo_flags_start */

  TODO_dump_func | TODO_update_ssa      /* todo_flags_finish */

    | TODO_verify_ssa

    | TODO_verify_stmts | TODO_verify_flow,

};

#include "gt-tree-vect-generic.h"