527 lines
16 KiB
C
527 lines
16 KiB
C
/* Lower vector operations to scalar operations.
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Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the
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Free Software Foundation; either version 2, or (at your option) any
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later version.
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GCC is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA. */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "tree.h"
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#include "tm.h"
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#include "rtl.h"
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#include "expr.h"
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#include "insn-codes.h"
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#include "diagnostic.h"
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#include "optabs.h"
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#include "machmode.h"
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#include "langhooks.h"
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#include "tree-flow.h"
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#include "tree-gimple.h"
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#include "tree-iterator.h"
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#include "tree-pass.h"
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#include "flags.h"
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#include "ggc.h"
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/* Build a constant of type TYPE, made of VALUE's bits replicated
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every TYPE_SIZE (INNER_TYPE) bits to fit TYPE's precision. */
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static tree
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build_replicated_const (tree type, tree inner_type, HOST_WIDE_INT value)
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{
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int width = tree_low_cst (TYPE_SIZE (inner_type), 1);
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int n = HOST_BITS_PER_WIDE_INT / width;
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unsigned HOST_WIDE_INT low, high, mask;
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tree ret;
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gcc_assert (n);
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if (width == HOST_BITS_PER_WIDE_INT)
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low = value;
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else
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{
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mask = ((HOST_WIDE_INT)1 << width) - 1;
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low = (unsigned HOST_WIDE_INT) ~0 / mask * (value & mask);
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}
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if (TYPE_PRECISION (type) < HOST_BITS_PER_WIDE_INT)
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low &= ((HOST_WIDE_INT)1 << TYPE_PRECISION (type)) - 1, high = 0;
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else if (TYPE_PRECISION (type) == HOST_BITS_PER_WIDE_INT)
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high = 0;
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else if (TYPE_PRECISION (type) == 2 * HOST_BITS_PER_WIDE_INT)
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high = low;
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else
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gcc_unreachable ();
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ret = build_int_cst_wide (type, low, high);
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return ret;
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}
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static GTY(()) tree vector_inner_type;
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static GTY(()) tree vector_last_type;
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static GTY(()) int vector_last_nunits;
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/* Return a suitable vector types made of SUBPARTS units each of mode
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"word_mode" (the global variable). */
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static tree
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build_word_mode_vector_type (int nunits)
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{
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if (!vector_inner_type)
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vector_inner_type = lang_hooks.types.type_for_mode (word_mode, 1);
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else if (vector_last_nunits == nunits)
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{
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gcc_assert (TREE_CODE (vector_last_type) == VECTOR_TYPE);
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return vector_last_type;
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}
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/* We build a new type, but we canonicalize it nevertheless,
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because it still saves some memory. */
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vector_last_nunits = nunits;
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vector_last_type = type_hash_canon (nunits,
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build_vector_type (vector_inner_type,
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nunits));
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return vector_last_type;
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}
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typedef tree (*elem_op_func) (block_stmt_iterator *,
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tree, tree, tree, tree, tree, enum tree_code);
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static inline tree
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tree_vec_extract (block_stmt_iterator *bsi, tree type,
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tree t, tree bitsize, tree bitpos)
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{
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if (bitpos)
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return gimplify_build3 (bsi, BIT_FIELD_REF, type, t, bitsize, bitpos);
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else
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return gimplify_build1 (bsi, VIEW_CONVERT_EXPR, type, t);
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}
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static tree
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do_unop (block_stmt_iterator *bsi, tree inner_type, tree a,
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tree b ATTRIBUTE_UNUSED, tree bitpos, tree bitsize,
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enum tree_code code)
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{
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a = tree_vec_extract (bsi, inner_type, a, bitsize, bitpos);
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return gimplify_build1 (bsi, code, inner_type, a);
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}
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static tree
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do_binop (block_stmt_iterator *bsi, tree inner_type, tree a, tree b,
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tree bitpos, tree bitsize, enum tree_code code)
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{
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a = tree_vec_extract (bsi, inner_type, a, bitsize, bitpos);
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b = tree_vec_extract (bsi, inner_type, b, bitsize, bitpos);
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return gimplify_build2 (bsi, code, inner_type, a, b);
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}
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/* Expand vector addition to scalars. This does bit twiddling
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in order to increase parallelism:
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a + b = (((int) a & 0x7f7f7f7f) + ((int) b & 0x7f7f7f7f)) ^
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(a ^ b) & 0x80808080
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a - b = (((int) a | 0x80808080) - ((int) b & 0x7f7f7f7f)) ^
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(a ^ ~b) & 0x80808080
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-b = (0x80808080 - ((int) b & 0x7f7f7f7f)) ^ (~b & 0x80808080)
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This optimization should be done only if 4 vector items or more
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fit into a word. */
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static tree
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do_plus_minus (block_stmt_iterator *bsi, tree word_type, tree a, tree b,
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tree bitpos ATTRIBUTE_UNUSED, tree bitsize ATTRIBUTE_UNUSED,
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enum tree_code code)
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{
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tree inner_type = TREE_TYPE (TREE_TYPE (a));
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unsigned HOST_WIDE_INT max;
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tree low_bits, high_bits, a_low, b_low, result_low, signs;
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max = GET_MODE_MASK (TYPE_MODE (inner_type));
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low_bits = build_replicated_const (word_type, inner_type, max >> 1);
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high_bits = build_replicated_const (word_type, inner_type, max & ~(max >> 1));
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a = tree_vec_extract (bsi, word_type, a, bitsize, bitpos);
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b = tree_vec_extract (bsi, word_type, b, bitsize, bitpos);
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signs = gimplify_build2 (bsi, BIT_XOR_EXPR, word_type, a, b);
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b_low = gimplify_build2 (bsi, BIT_AND_EXPR, word_type, b, low_bits);
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if (code == PLUS_EXPR)
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a_low = gimplify_build2 (bsi, BIT_AND_EXPR, word_type, a, low_bits);
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else
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{
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a_low = gimplify_build2 (bsi, BIT_IOR_EXPR, word_type, a, high_bits);
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signs = gimplify_build1 (bsi, BIT_NOT_EXPR, word_type, signs);
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}
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signs = gimplify_build2 (bsi, BIT_AND_EXPR, word_type, signs, high_bits);
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result_low = gimplify_build2 (bsi, code, word_type, a_low, b_low);
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return gimplify_build2 (bsi, BIT_XOR_EXPR, word_type, result_low, signs);
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}
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static tree
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do_negate (block_stmt_iterator *bsi, tree word_type, tree b,
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tree unused ATTRIBUTE_UNUSED, tree bitpos ATTRIBUTE_UNUSED,
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tree bitsize ATTRIBUTE_UNUSED,
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enum tree_code code ATTRIBUTE_UNUSED)
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{
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tree inner_type = TREE_TYPE (TREE_TYPE (b));
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HOST_WIDE_INT max;
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tree low_bits, high_bits, b_low, result_low, signs;
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max = GET_MODE_MASK (TYPE_MODE (inner_type));
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low_bits = build_replicated_const (word_type, inner_type, max >> 1);
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high_bits = build_replicated_const (word_type, inner_type, max & ~(max >> 1));
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b = tree_vec_extract (bsi, word_type, b, bitsize, bitpos);
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b_low = gimplify_build2 (bsi, BIT_AND_EXPR, word_type, b, low_bits);
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signs = gimplify_build1 (bsi, BIT_NOT_EXPR, word_type, b);
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signs = gimplify_build2 (bsi, BIT_AND_EXPR, word_type, signs, high_bits);
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result_low = gimplify_build2 (bsi, MINUS_EXPR, word_type, high_bits, b_low);
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return gimplify_build2 (bsi, BIT_XOR_EXPR, word_type, result_low, signs);
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}
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/* Expand a vector operation to scalars, by using many operations
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whose type is the vector type's inner type. */
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static tree
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expand_vector_piecewise (block_stmt_iterator *bsi, elem_op_func f,
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tree type, tree inner_type,
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tree a, tree b, enum tree_code code)
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{
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VEC(constructor_elt,gc) *v;
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tree part_width = TYPE_SIZE (inner_type);
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tree index = bitsize_int (0);
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int nunits = TYPE_VECTOR_SUBPARTS (type);
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int delta = tree_low_cst (part_width, 1)
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/ tree_low_cst (TYPE_SIZE (TREE_TYPE (type)), 1);
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int i;
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v = VEC_alloc(constructor_elt, gc, (nunits + delta - 1) / delta);
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for (i = 0; i < nunits;
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i += delta, index = int_const_binop (PLUS_EXPR, index, part_width, 0))
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{
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tree result = f (bsi, inner_type, a, b, index, part_width, code);
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constructor_elt *ce = VEC_quick_push (constructor_elt, v, NULL);
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ce->index = NULL_TREE;
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ce->value = result;
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}
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return build_constructor (type, v);
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}
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/* Expand a vector operation to scalars with the freedom to use
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a scalar integer type, or to use a different size for the items
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in the vector type. */
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static tree
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expand_vector_parallel (block_stmt_iterator *bsi, elem_op_func f, tree type,
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tree a, tree b,
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enum tree_code code)
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{
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tree result, compute_type;
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enum machine_mode mode;
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int n_words = tree_low_cst (TYPE_SIZE_UNIT (type), 1) / UNITS_PER_WORD;
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/* We have three strategies. If the type is already correct, just do
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the operation an element at a time. Else, if the vector is wider than
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one word, do it a word at a time; finally, if the vector is smaller
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than one word, do it as a scalar. */
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if (TYPE_MODE (TREE_TYPE (type)) == word_mode)
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return expand_vector_piecewise (bsi, f,
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type, TREE_TYPE (type),
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a, b, code);
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else if (n_words > 1)
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{
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tree word_type = build_word_mode_vector_type (n_words);
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result = expand_vector_piecewise (bsi, f,
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word_type, TREE_TYPE (word_type),
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a, b, code);
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result = gimplify_val (bsi, word_type, result);
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}
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else
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{
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/* Use a single scalar operation with a mode no wider than word_mode. */
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mode = mode_for_size (tree_low_cst (TYPE_SIZE (type), 1), MODE_INT, 0);
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compute_type = lang_hooks.types.type_for_mode (mode, 1);
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result = f (bsi, compute_type, a, b, NULL_TREE, NULL_TREE, code);
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}
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return result;
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}
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/* Expand a vector operation to scalars; for integer types we can use
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special bit twiddling tricks to do the sums a word at a time, using
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function F_PARALLEL instead of F. These tricks are done only if
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they can process at least four items, that is, only if the vector
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holds at least four items and if a word can hold four items. */
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static tree
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expand_vector_addition (block_stmt_iterator *bsi,
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elem_op_func f, elem_op_func f_parallel,
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tree type, tree a, tree b, enum tree_code code)
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{
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int parts_per_word = UNITS_PER_WORD
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/ tree_low_cst (TYPE_SIZE_UNIT (TREE_TYPE (type)), 1);
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if (INTEGRAL_TYPE_P (TREE_TYPE (type))
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&& parts_per_word >= 4
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&& TYPE_VECTOR_SUBPARTS (type) >= 4)
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return expand_vector_parallel (bsi, f_parallel,
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type, a, b, code);
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else
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return expand_vector_piecewise (bsi, f,
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type, TREE_TYPE (type),
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a, b, code);
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}
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static tree
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expand_vector_operation (block_stmt_iterator *bsi, tree type, tree compute_type,
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tree rhs, enum tree_code code)
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{
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enum machine_mode compute_mode = TYPE_MODE (compute_type);
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/* If the compute mode is not a vector mode (hence we are not decomposing
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a BLKmode vector to smaller, hardware-supported vectors), we may want
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to expand the operations in parallel. */
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if (GET_MODE_CLASS (compute_mode) != MODE_VECTOR_INT
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&& GET_MODE_CLASS (compute_mode) != MODE_VECTOR_FLOAT)
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switch (code)
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{
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case PLUS_EXPR:
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case MINUS_EXPR:
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if (!TYPE_OVERFLOW_TRAPS (type))
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return expand_vector_addition (bsi, do_binop, do_plus_minus, type,
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TREE_OPERAND (rhs, 0),
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TREE_OPERAND (rhs, 1), code);
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break;
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case NEGATE_EXPR:
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if (!TYPE_OVERFLOW_TRAPS (type))
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return expand_vector_addition (bsi, do_unop, do_negate, type,
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TREE_OPERAND (rhs, 0),
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NULL_TREE, code);
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break;
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case BIT_AND_EXPR:
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case BIT_IOR_EXPR:
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case BIT_XOR_EXPR:
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return expand_vector_parallel (bsi, do_binop, type,
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TREE_OPERAND (rhs, 0),
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TREE_OPERAND (rhs, 1), code);
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case BIT_NOT_EXPR:
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return expand_vector_parallel (bsi, do_unop, type,
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TREE_OPERAND (rhs, 0),
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NULL_TREE, code);
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default:
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break;
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}
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if (TREE_CODE_CLASS (code) == tcc_unary)
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return expand_vector_piecewise (bsi, do_unop, type, compute_type,
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TREE_OPERAND (rhs, 0),
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NULL_TREE, code);
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else
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return expand_vector_piecewise (bsi, do_binop, type, compute_type,
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TREE_OPERAND (rhs, 0),
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TREE_OPERAND (rhs, 1), code);
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}
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/* Return a type for the widest vector mode whose components are of mode
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INNER_MODE, or NULL_TREE if none is found. */
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static tree
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type_for_widest_vector_mode (enum machine_mode inner_mode, optab op)
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{
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enum machine_mode best_mode = VOIDmode, mode;
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int best_nunits = 0;
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if (SCALAR_FLOAT_MODE_P (inner_mode))
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mode = MIN_MODE_VECTOR_FLOAT;
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else
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mode = MIN_MODE_VECTOR_INT;
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for (; mode != VOIDmode; mode = GET_MODE_WIDER_MODE (mode))
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if (GET_MODE_INNER (mode) == inner_mode
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&& GET_MODE_NUNITS (mode) > best_nunits
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&& op->handlers[mode].insn_code != CODE_FOR_nothing)
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best_mode = mode, best_nunits = GET_MODE_NUNITS (mode);
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if (best_mode == VOIDmode)
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return NULL_TREE;
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else
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return lang_hooks.types.type_for_mode (best_mode, 1);
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}
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/* Process one statement. If we identify a vector operation, expand it. */
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static void
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expand_vector_operations_1 (block_stmt_iterator *bsi)
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{
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tree stmt = bsi_stmt (*bsi);
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tree *p_lhs, *p_rhs, lhs, rhs, type, compute_type;
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enum tree_code code;
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enum machine_mode compute_mode;
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optab op;
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switch (TREE_CODE (stmt))
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{
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case RETURN_EXPR:
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stmt = TREE_OPERAND (stmt, 0);
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if (!stmt || TREE_CODE (stmt) != MODIFY_EXPR)
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return;
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/* FALLTHRU */
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case MODIFY_EXPR:
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p_lhs = &TREE_OPERAND (stmt, 0);
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p_rhs = &TREE_OPERAND (stmt, 1);
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lhs = *p_lhs;
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rhs = *p_rhs;
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break;
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default:
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return;
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}
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type = TREE_TYPE (rhs);
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if (TREE_CODE (type) != VECTOR_TYPE)
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return;
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code = TREE_CODE (rhs);
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if (TREE_CODE_CLASS (code) != tcc_unary
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&& TREE_CODE_CLASS (code) != tcc_binary)
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return;
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if (code == NOP_EXPR || code == VIEW_CONVERT_EXPR)
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return;
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gcc_assert (code != CONVERT_EXPR);
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op = optab_for_tree_code (code, type);
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/* For widening vector operations, the relevant type is of the arguments,
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not the widened result. */
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if (code == WIDEN_SUM_EXPR)
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type = TREE_TYPE (TREE_OPERAND (rhs, 0));
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/* Optabs will try converting a negation into a subtraction, so
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look for it as well. TODO: negation of floating-point vectors
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might be turned into an exclusive OR toggling the sign bit. */
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if (op == NULL
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&& code == NEGATE_EXPR
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&& INTEGRAL_TYPE_P (TREE_TYPE (type)))
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op = optab_for_tree_code (MINUS_EXPR, type);
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/* For very wide vectors, try using a smaller vector mode. */
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compute_type = type;
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if (TYPE_MODE (type) == BLKmode && op)
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{
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tree vector_compute_type
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= type_for_widest_vector_mode (TYPE_MODE (TREE_TYPE (type)), op);
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if (vector_compute_type != NULL_TREE)
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compute_type = vector_compute_type;
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}
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/* If we are breaking a BLKmode vector into smaller pieces,
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type_for_widest_vector_mode has already looked into the optab,
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so skip these checks. */
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if (compute_type == type)
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{
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compute_mode = TYPE_MODE (compute_type);
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if ((GET_MODE_CLASS (compute_mode) == MODE_VECTOR_INT
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|| GET_MODE_CLASS (compute_mode) == MODE_VECTOR_FLOAT)
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&& op != NULL
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&& op->handlers[compute_mode].insn_code != CODE_FOR_nothing)
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return;
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else
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/* There is no operation in hardware, so fall back to scalars. */
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compute_type = TREE_TYPE (type);
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}
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gcc_assert (code != VEC_LSHIFT_EXPR && code != VEC_RSHIFT_EXPR);
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rhs = expand_vector_operation (bsi, type, compute_type, rhs, code);
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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 unsigned int
|
||
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));
|
||
}
|
||
}
|
||
return 0;
|
||
}
|
||
|
||
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 */
|
||
0 /* letter */
|
||
};
|
||
|
||
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,
|
||
0 /* letter */
|
||
};
|
||
|
||
#include "gt-tree-vect-generic.h"
|