gcc/tree-vect-generic.c - gcc - Git at Google

 /* Lower vector operations to scalar operations.
    Copyright (C) 2004, 2005, 2006, 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 "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 "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) (gimple_stmt_iterator *,
 			      tree, tree, tree, tree, tree, enum tree_code);

 static inline tree
 tree_vec_extract (gimple_stmt_iterator *gsi, tree type,
 		  tree t, tree bitsize, tree bitpos)
 {
   if (bitpos)
     return gimplify_build3 (gsi, BIT_FIELD_REF, type, t, bitsize, bitpos);
   else
     return gimplify_build1 (gsi, VIEW_CONVERT_EXPR, type, t);
 }

 static tree
 do_unop (gimple_stmt_iterator *gsi, tree inner_type, tree a,
 	 tree b ATTRIBUTE_UNUSED, tree bitpos, tree bitsize,
 	 enum tree_code code)
 {
   a = tree_vec_extract (gsi, inner_type, a, bitsize, bitpos);
   return gimplify_build1 (gsi, code, inner_type, a);
 }

 static tree
 do_binop (gimple_stmt_iterator *gsi, tree inner_type, tree a, tree b,
 	  tree bitpos, tree bitsize, enum tree_code code)
 {
   a = tree_vec_extract (gsi, inner_type, a, bitsize, bitpos);
   b = tree_vec_extract (gsi, inner_type, b, bitsize, bitpos);
   return gimplify_build2 (gsi, 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 (gimple_stmt_iterator *gsi, 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 (gsi, word_type, a, bitsize, bitpos);
   b = tree_vec_extract (gsi, word_type, b, bitsize, bitpos);

   signs = gimplify_build2 (gsi, BIT_XOR_EXPR, word_type, a, b);
   b_low = gimplify_build2 (gsi, BIT_AND_EXPR, word_type, b, low_bits);
   if (code == PLUS_EXPR)
     a_low = gimplify_build2 (gsi, BIT_AND_EXPR, word_type, a, low_bits);
   else
     {
       a_low = gimplify_build2 (gsi, BIT_IOR_EXPR, word_type, a, high_bits);
       signs = gimplify_build1 (gsi, BIT_NOT_EXPR, word_type, signs);
     }

   signs = gimplify_build2 (gsi, BIT_AND_EXPR, word_type, signs, high_bits);
   result_low = gimplify_build2 (gsi, code, word_type, a_low, b_low);
   return gimplify_build2 (gsi, BIT_XOR_EXPR, word_type, result_low, signs);
 }

 static tree
 do_negate (gimple_stmt_iterator *gsi, 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 (gsi, word_type, b, bitsize, bitpos);

   b_low = gimplify_build2 (gsi, BIT_AND_EXPR, word_type, b, low_bits);
   signs = gimplify_build1 (gsi, BIT_NOT_EXPR, word_type, b);
   signs = gimplify_build2 (gsi, BIT_AND_EXPR, word_type, signs, high_bits);
   result_low = gimplify_build2 (gsi, MINUS_EXPR, word_type, high_bits, b_low);
   return gimplify_build2 (gsi, 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 (gimple_stmt_iterator *gsi, 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 (gsi, 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 (gimple_stmt_iterator *gsi, 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 (gsi, 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 (gsi, f,
 				        word_type, TREE_TYPE (word_type),
 					a, b, code);
       result = force_gimple_operand_gsi (gsi, result, true, NULL, true,
                                          GSI_SAME_STMT);
     }
   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 (gsi, 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 (gimple_stmt_iterator *gsi,
 			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 (gsi, f_parallel,
 				   type, a, b, code);
   else
     return expand_vector_piecewise (gsi, f,
 				    type, TREE_TYPE (type),
 				    a, b, code);
 }

 static tree
 expand_vector_operation (gimple_stmt_iterator *gsi, tree type, tree compute_type,
 			 gimple assign, 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
       && GET_MODE_CLASS (compute_mode) != MODE_VECTOR_FRACT
       && GET_MODE_CLASS (compute_mode) != MODE_VECTOR_UFRACT
       && GET_MODE_CLASS (compute_mode) != MODE_VECTOR_ACCUM
       && GET_MODE_CLASS (compute_mode) != MODE_VECTOR_UACCUM)
     switch (code)
       {
       case PLUS_EXPR:
       case MINUS_EXPR:
         if (!TYPE_OVERFLOW_TRAPS (type))
           return expand_vector_addition (gsi, do_binop, do_plus_minus, type,
 		      		         gimple_assign_rhs1 (assign),
 					 gimple_assign_rhs2 (assign), code);
 	break;

       case NEGATE_EXPR:
         if (!TYPE_OVERFLOW_TRAPS (type))
           return expand_vector_addition (gsi, do_unop, do_negate, type,
 		      		         gimple_assign_rhs1 (assign),
 					 NULL_TREE, code);
 	break;

       case BIT_AND_EXPR:
       case BIT_IOR_EXPR:
       case BIT_XOR_EXPR:
         return expand_vector_parallel (gsi, do_binop, type,
 		      		       gimple_assign_rhs1 (assign),
 				       gimple_assign_rhs2 (assign), code);

       case BIT_NOT_EXPR:
         return expand_vector_parallel (gsi, do_unop, type,
 		      		       gimple_assign_rhs1 (assign),
 				       NULL_TREE, code);

       default:
 	break;
       }

   if (TREE_CODE_CLASS (code) == tcc_unary)
     return expand_vector_piecewise (gsi, do_unop, type, compute_type,
 				    gimple_assign_rhs1 (assign),
 				    NULL_TREE, code);
   else
     return expand_vector_piecewise (gsi, do_binop, type, compute_type,
 				    gimple_assign_rhs1 (assign),
 				    gimple_assign_rhs2 (assign), code);
 }

 /* Return a type for the widest vector mode whose components are of mode
    INNER_MODE, or NULL_TREE if none is found.
    SATP is true for saturating fixed-point types.  */

 static tree
 type_for_widest_vector_mode (enum machine_mode inner_mode, optab op, int satp)
 {
   enum machine_mode best_mode = VOIDmode, mode;
   int best_nunits = 0;

   if (SCALAR_FLOAT_MODE_P (inner_mode))
     mode = MIN_MODE_VECTOR_FLOAT;
   else if (SCALAR_FRACT_MODE_P (inner_mode))
     mode = MIN_MODE_VECTOR_FRACT;
   else if (SCALAR_UFRACT_MODE_P (inner_mode))
     mode = MIN_MODE_VECTOR_UFRACT;
   else if (SCALAR_ACCUM_MODE_P (inner_mode))
     mode = MIN_MODE_VECTOR_ACCUM;
   else if (SCALAR_UACCUM_MODE_P (inner_mode))
     mode = MIN_MODE_VECTOR_UACCUM;
   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
 	&& optab_handler (op, mode)->insn_code != CODE_FOR_nothing)
       best_mode = mode, best_nunits = GET_MODE_NUNITS (mode);

   if (best_mode == VOIDmode)
     return NULL_TREE;
   else
     {
       /* For fixed-point modes, we need to pass satp as the 2nd parameter.  */
       if (ALL_FIXED_POINT_MODE_P (best_mode))
 	return lang_hooks.types.type_for_mode (best_mode, satp);

       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 (gimple_stmt_iterator *gsi)
 {
   gimple stmt = gsi_stmt (*gsi);
   tree lhs, rhs1, rhs2 = NULL, type, compute_type;
   enum tree_code code;
   enum machine_mode compute_mode;
   optab op;
   enum gimple_rhs_class rhs_class;
   tree new_rhs;

   if (gimple_code (stmt) != GIMPLE_ASSIGN)
     return;

   code = gimple_assign_rhs_code (stmt);
   rhs_class = get_gimple_rhs_class (code);

   if (rhs_class != GIMPLE_UNARY_RHS && rhs_class != GIMPLE_BINARY_RHS)
     return;

   lhs = gimple_assign_lhs (stmt);
   rhs1 = gimple_assign_rhs1 (stmt);
   type = gimple_expr_type (stmt);
   if (rhs_class == GIMPLE_BINARY_RHS)
     rhs2 = gimple_assign_rhs2 (stmt);

   if (TREE_CODE (type) != VECTOR_TYPE)
     return;

   if (code == NOP_EXPR
       || code == FLOAT_EXPR
       || code == FIX_TRUNC_EXPR
       || code == VIEW_CONVERT_EXPR)
     return;

   gcc_assert (code != CONVERT_EXPR);

   /* The signedness is determined from input argument.  */
   if (code == VEC_UNPACK_FLOAT_HI_EXPR
       || code == VEC_UNPACK_FLOAT_LO_EXPR)
     type = TREE_TYPE (rhs1);

   /* Choose between vector shift/rotate by vector and vector shift/rotate by
      scalar */
   if (code == LSHIFT_EXPR
       || code == RSHIFT_EXPR
       || code == LROTATE_EXPR
       || code == RROTATE_EXPR)
     {
       /* If the 2nd argument is vector, we need a vector/vector shift */
       if (VECTOR_MODE_P (TYPE_MODE (TREE_TYPE (rhs2))))
 	op = optab_for_tree_code (code, type, optab_vector);
       else
 	{
 	  /* Try for a vector/scalar shift, and if we don't have one, see if we
 	     have a vector/vector shift */
 	  op = optab_for_tree_code (code, type, optab_scalar);
 	  if (!op
 	      || (op->handlers[(int) TYPE_MODE (type)].insn_code
 		  == CODE_FOR_nothing))
 	    op = optab_for_tree_code (code, type, optab_vector);
 	}
     }
   else
     op = optab_for_tree_code (code, type, optab_default);

   /* For widening/narrowing vector operations, the relevant type is of the
      arguments, not the widened result.  VEC_UNPACK_FLOAT_*_EXPR is
      calculated in the same way above.  */
   if (code == WIDEN_SUM_EXPR
       || code == VEC_WIDEN_MULT_HI_EXPR
       || code == VEC_WIDEN_MULT_LO_EXPR
       || code == VEC_UNPACK_HI_EXPR
       || code == VEC_UNPACK_LO_EXPR
       || code == VEC_PACK_TRUNC_EXPR
       || code == VEC_PACK_SAT_EXPR
       || code == VEC_PACK_FIX_TRUNC_EXPR)
     type = TREE_TYPE (rhs1);

   /* 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, optab_default);

   /* 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,
 				       TYPE_SATURATING (TREE_TYPE (type)));
       if (vector_compute_type != NULL_TREE
 	  && (TYPE_VECTOR_SUBPARTS (vector_compute_type)
 	      < TYPE_VECTOR_SUBPARTS (compute_type)))
 	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
 	   || GET_MODE_CLASS (compute_mode) == MODE_VECTOR_FRACT
 	   || GET_MODE_CLASS (compute_mode) == MODE_VECTOR_UFRACT
 	   || GET_MODE_CLASS (compute_mode) == MODE_VECTOR_ACCUM
 	   || GET_MODE_CLASS (compute_mode) == MODE_VECTOR_UACCUM)
           && op != NULL
 	  && optab_handler (op, 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);
   new_rhs = expand_vector_operation (gsi, type, compute_type, stmt, code);
   if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (new_rhs)))
     new_rhs = gimplify_build1 (gsi, VIEW_CONVERT_EXPR, TREE_TYPE (lhs),
                                new_rhs);

   /* NOTE:  We should avoid using gimple_assign_set_rhs_from_tree. One
      way to do it is change expand_vector_operation and its callees to
      return a tree_code, RHS1 and RHS2 instead of a tree. */
   gimple_assign_set_rhs_from_tree (gsi, new_rhs);

   gimple_set_modified (gsi_stmt (*gsi), true);
 }

 /* 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 unsigned int
 expand_vector_operations (void)
 {
   gimple_stmt_iterator gsi;
   basic_block bb;

   FOR_EACH_BB (bb)
     {
       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 	{
 	  expand_vector_operations_1 (&gsi);
 	  update_stmt_if_modified (gsi_stmt (gsi));
 	}
     }
   return 0;
 }

 struct gimple_opt_pass pass_lower_vector =
 {
  {
   GIMPLE_PASS,
   "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 gimple_opt_pass pass_lower_vector_ssa =
 {
  {
   GIMPLE_PASS,
   "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"
	/* Lower vector operations to scalar operations.
	Copyright (C) 2004, 2005, 2006, 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 "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 "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) (gimple_stmt_iterator ,
	tree, tree, tree, tree, tree, enum tree_code);

	static inline tree
	tree_vec_extract (gimple_stmt_iterator *gsi, tree type,
	tree t, tree bitsize, tree bitpos)
	{
	if (bitpos)
	return gimplify_build3 (gsi, BIT_FIELD_REF, type, t, bitsize, bitpos);
	else
	return gimplify_build1 (gsi, VIEW_CONVERT_EXPR, type, t);
	}

	static tree
	do_unop (gimple_stmt_iterator *gsi, tree inner_type, tree a,
	tree b ATTRIBUTE_UNUSED, tree bitpos, tree bitsize,
	enum tree_code code)
	{
	a = tree_vec_extract (gsi, inner_type, a, bitsize, bitpos);
	return gimplify_build1 (gsi, code, inner_type, a);
	}

	static tree
	do_binop (gimple_stmt_iterator *gsi, tree inner_type, tree a, tree b,
	tree bitpos, tree bitsize, enum tree_code code)
	{
	a = tree_vec_extract (gsi, inner_type, a, bitsize, bitpos);
	b = tree_vec_extract (gsi, inner_type, b, bitsize, bitpos);
	return gimplify_build2 (gsi, 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 (gimple_stmt_iterator *gsi, 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 (gsi, word_type, a, bitsize, bitpos);
	b = tree_vec_extract (gsi, word_type, b, bitsize, bitpos);

	signs = gimplify_build2 (gsi, BIT_XOR_EXPR, word_type, a, b);
	b_low = gimplify_build2 (gsi, BIT_AND_EXPR, word_type, b, low_bits);
	if (code == PLUS_EXPR)
	a_low = gimplify_build2 (gsi, BIT_AND_EXPR, word_type, a, low_bits);
	else
	{
	a_low = gimplify_build2 (gsi, BIT_IOR_EXPR, word_type, a, high_bits);
	signs = gimplify_build1 (gsi, BIT_NOT_EXPR, word_type, signs);
	}

	signs = gimplify_build2 (gsi, BIT_AND_EXPR, word_type, signs, high_bits);
	result_low = gimplify_build2 (gsi, code, word_type, a_low, b_low);
	return gimplify_build2 (gsi, BIT_XOR_EXPR, word_type, result_low, signs);
	}

	static tree
	do_negate (gimple_stmt_iterator *gsi, 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 (gsi, word_type, b, bitsize, bitpos);

	b_low = gimplify_build2 (gsi, BIT_AND_EXPR, word_type, b, low_bits);
	signs = gimplify_build1 (gsi, BIT_NOT_EXPR, word_type, b);
	signs = gimplify_build2 (gsi, BIT_AND_EXPR, word_type, signs, high_bits);
	result_low = gimplify_build2 (gsi, MINUS_EXPR, word_type, high_bits, b_low);
	return gimplify_build2 (gsi, 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 (gimple_stmt_iterator *gsi, 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 (gsi, 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 (gimple_stmt_iterator *gsi, 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 (gsi, 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 (gsi, f,
	word_type, TREE_TYPE (word_type),
	a, b, code);
	result = force_gimple_operand_gsi (gsi, result, true, NULL, true,
	GSI_SAME_STMT);
	}
	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 (gsi, 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 (gimple_stmt_iterator *gsi,
	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 (gsi, f_parallel,
	type, a, b, code);
	else
	return expand_vector_piecewise (gsi, f,
	type, TREE_TYPE (type),
	a, b, code);
	}

	static tree
	expand_vector_operation (gimple_stmt_iterator *gsi, tree type, tree compute_type,
	gimple assign, 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
	&& GET_MODE_CLASS (compute_mode) != MODE_VECTOR_FRACT
	&& GET_MODE_CLASS (compute_mode) != MODE_VECTOR_UFRACT
	&& GET_MODE_CLASS (compute_mode) != MODE_VECTOR_ACCUM
	&& GET_MODE_CLASS (compute_mode) != MODE_VECTOR_UACCUM)
	switch (code)
	{
	case PLUS_EXPR:
	case MINUS_EXPR:
	if (!TYPE_OVERFLOW_TRAPS (type))
	return expand_vector_addition (gsi, do_binop, do_plus_minus, type,
	gimple_assign_rhs1 (assign),
	gimple_assign_rhs2 (assign), code);
	break;

	case NEGATE_EXPR:
	if (!TYPE_OVERFLOW_TRAPS (type))
	return expand_vector_addition (gsi, do_unop, do_negate, type,
	gimple_assign_rhs1 (assign),
	NULL_TREE, code);
	break;

	case BIT_AND_EXPR:
	case BIT_IOR_EXPR:
	case BIT_XOR_EXPR:
	return expand_vector_parallel (gsi, do_binop, type,
	gimple_assign_rhs1 (assign),
	gimple_assign_rhs2 (assign), code);

	case BIT_NOT_EXPR:
	return expand_vector_parallel (gsi, do_unop, type,
	gimple_assign_rhs1 (assign),
	NULL_TREE, code);

	default:
	break;
	}

	if (TREE_CODE_CLASS (code) == tcc_unary)
	return expand_vector_piecewise (gsi, do_unop, type, compute_type,
	gimple_assign_rhs1 (assign),
	NULL_TREE, code);
	else
	return expand_vector_piecewise (gsi, do_binop, type, compute_type,
	gimple_assign_rhs1 (assign),
	gimple_assign_rhs2 (assign), code);
	}

	/* Return a type for the widest vector mode whose components are of mode
	INNER_MODE, or NULL_TREE if none is found.
	SATP is true for saturating fixed-point types. */

	static tree
	type_for_widest_vector_mode (enum machine_mode inner_mode, optab op, int satp)
	{
	enum machine_mode best_mode = VOIDmode, mode;
	int best_nunits = 0;

	if (SCALAR_FLOAT_MODE_P (inner_mode))
	mode = MIN_MODE_VECTOR_FLOAT;
	else if (SCALAR_FRACT_MODE_P (inner_mode))
	mode = MIN_MODE_VECTOR_FRACT;
	else if (SCALAR_UFRACT_MODE_P (inner_mode))
	mode = MIN_MODE_VECTOR_UFRACT;
	else if (SCALAR_ACCUM_MODE_P (inner_mode))
	mode = MIN_MODE_VECTOR_ACCUM;
	else if (SCALAR_UACCUM_MODE_P (inner_mode))
	mode = MIN_MODE_VECTOR_UACCUM;
	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
	&& optab_handler (op, mode)->insn_code != CODE_FOR_nothing)
	best_mode = mode, best_nunits = GET_MODE_NUNITS (mode);

	if (best_mode == VOIDmode)
	return NULL_TREE;
	else
	{
	/* For fixed-point modes, we need to pass satp as the 2nd parameter. */
	if (ALL_FIXED_POINT_MODE_P (best_mode))
	return lang_hooks.types.type_for_mode (best_mode, satp);

	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 (gimple_stmt_iterator *gsi)
	{
	gimple stmt = gsi_stmt (*gsi);
	tree lhs, rhs1, rhs2 = NULL, type, compute_type;
	enum tree_code code;
	enum machine_mode compute_mode;
	optab op;
	enum gimple_rhs_class rhs_class;
	tree new_rhs;

	if (gimple_code (stmt) != GIMPLE_ASSIGN)
	return;

	code = gimple_assign_rhs_code (stmt);
	rhs_class = get_gimple_rhs_class (code);

	if (rhs_class != GIMPLE_UNARY_RHS && rhs_class != GIMPLE_BINARY_RHS)
	return;

	lhs = gimple_assign_lhs (stmt);
	rhs1 = gimple_assign_rhs1 (stmt);
	type = gimple_expr_type (stmt);
	if (rhs_class == GIMPLE_BINARY_RHS)
	rhs2 = gimple_assign_rhs2 (stmt);

	if (TREE_CODE (type) != VECTOR_TYPE)
	return;

	if (code == NOP_EXPR
	\|\| code == FLOAT_EXPR
	\|\| code == FIX_TRUNC_EXPR
	\|\| code == VIEW_CONVERT_EXPR)
	return;

	gcc_assert (code != CONVERT_EXPR);

	/* The signedness is determined from input argument. */
	if (code == VEC_UNPACK_FLOAT_HI_EXPR
	\|\| code == VEC_UNPACK_FLOAT_LO_EXPR)
	type = TREE_TYPE (rhs1);

	/* Choose between vector shift/rotate by vector and vector shift/rotate by
	scalar */
	if (code == LSHIFT_EXPR
	\|\| code == RSHIFT_EXPR
	\|\| code == LROTATE_EXPR
	\|\| code == RROTATE_EXPR)
	{
	/* If the 2nd argument is vector, we need a vector/vector shift */
	if (VECTOR_MODE_P (TYPE_MODE (TREE_TYPE (rhs2))))
	op = optab_for_tree_code (code, type, optab_vector);
	else
	{
	/* Try for a vector/scalar shift, and if we don't have one, see if we
	have a vector/vector shift */
	op = optab_for_tree_code (code, type, optab_scalar);
	if (!op
	\|\| (op->handlers[(int) TYPE_MODE (type)].insn_code
	== CODE_FOR_nothing))
	op = optab_for_tree_code (code, type, optab_vector);
	}
	}
	else
	op = optab_for_tree_code (code, type, optab_default);

	/* For widening/narrowing vector operations, the relevant type is of the
	arguments, not the widened result. VEC_UNPACK_FLOAT_*_EXPR is
	calculated in the same way above. */
	if (code == WIDEN_SUM_EXPR
	\|\| code == VEC_WIDEN_MULT_HI_EXPR
	\|\| code == VEC_WIDEN_MULT_LO_EXPR
	\|\| code == VEC_UNPACK_HI_EXPR
	\|\| code == VEC_UNPACK_LO_EXPR
	\|\| code == VEC_PACK_TRUNC_EXPR
	\|\| code == VEC_PACK_SAT_EXPR
	\|\| code == VEC_PACK_FIX_TRUNC_EXPR)
	type = TREE_TYPE (rhs1);

	/* 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, optab_default);

	/* 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,
	TYPE_SATURATING (TREE_TYPE (type)));
	if (vector_compute_type != NULL_TREE
	&& (TYPE_VECTOR_SUBPARTS (vector_compute_type)
	< TYPE_VECTOR_SUBPARTS (compute_type)))
	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
	\|\| GET_MODE_CLASS (compute_mode) == MODE_VECTOR_FRACT
	\|\| GET_MODE_CLASS (compute_mode) == MODE_VECTOR_UFRACT
	\|\| GET_MODE_CLASS (compute_mode) == MODE_VECTOR_ACCUM
	\|\| GET_MODE_CLASS (compute_mode) == MODE_VECTOR_UACCUM)
	&& op != NULL
	&& optab_handler (op, 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);
	new_rhs = expand_vector_operation (gsi, type, compute_type, stmt, code);
	if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (new_rhs)))
	new_rhs = gimplify_build1 (gsi, VIEW_CONVERT_EXPR, TREE_TYPE (lhs),
	new_rhs);

	/* NOTE: We should avoid using gimple_assign_set_rhs_from_tree. One
	way to do it is change expand_vector_operation and its callees to
	return a tree_code, RHS1 and RHS2 instead of a tree. */
	gimple_assign_set_rhs_from_tree (gsi, new_rhs);

	gimple_set_modified (gsi_stmt (*gsi), true);
	}

	/* 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 unsigned int
	expand_vector_operations (void)
	{
	gimple_stmt_iterator gsi;
	basic_block bb;

	FOR_EACH_BB (bb)
	{
	for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
	{
	expand_vector_operations_1 (&gsi);
	update_stmt_if_modified (gsi_stmt (gsi));
	}
	}
	return 0;
	}

	struct gimple_opt_pass pass_lower_vector =
	{
	{
	GIMPLE_PASS,
	"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 gimple_opt_pass pass_lower_vector_ssa =
	{
	{
	GIMPLE_PASS,
	"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"