1 /* A representation of vector permutation indices.
2 Copyright (C) 2017-2023 Free Software Foundation, Inc.
3
4 This file is part of GCC.
5
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
10
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
19
20 #ifndef GCC_VEC_PERN_INDICES_H
21 #define GCC_VEC_PERN_INDICES_H 1
22
23 #include "int-vector-builder.h"
24
25 /* A vector_builder for building constant permutation vectors.
26 The elements do not need to be clamped to a particular range
27 of input elements. */
28 typedef int_vector_builder<poly_int64> vec_perm_builder;
29
30 /* This class represents a constant permutation vector, such as that used
31 as the final operand to a VEC_PERM_EXPR.
32
33 Permutation vectors select indices modulo the number of input elements,
34 and the class canonicalizes each permutation vector for a particular
35 number of input vectors and for a particular number of elements per
36 input. For example, the gimple statements:
37
38 _1 = VEC_PERM_EXPR <a, a, { 0, 2, 4, 6, 0, 2, 4, 6 }>;
39 _2 = VEC_PERM_EXPR <a, a, { 0, 2, 4, 6, 8, 10, 12, 14 }>;
40 _3 = VEC_PERM_EXPR <a, a, { 0, 2, 20, 22, 24, 2, 4, 14 }>;
41
42 effectively have only a single vector input "a". If "a" has 8
43 elements, the indices select elements modulo 8, which makes all three
44 VEC_PERM_EXPRs equivalent. The canonical form is for the indices to be
45 in the range [0, number of input elements - 1], so the class treats the
46 second and third permutation vectors as though they had been the first.
47
48 The class copes with cases in which the input and output vectors have
49 different numbers of elements. */
50 class vec_perm_indices
51 {
52 typedef poly_int64 element_type;
53
54 public:
55 vec_perm_indices ();
56 vec_perm_indices (const vec_perm_builder &, unsigned int, poly_uint64);
57
58 void new_vector (const vec_perm_builder &, unsigned int, poly_uint64);
59 void new_expanded_vector (const vec_perm_indices &, unsigned int);
60 bool new_shrunk_vector (const vec_perm_indices &, unsigned int);
61 void rotate_inputs (int delta);
62
63 /* Return the underlying vector encoding. */
64 const vec_perm_builder &encoding () const { return m_encoding; }
65
66 /* Return the number of output elements. This is called length ()
67 so that we present a more vec-like interface. */
68 poly_uint64 length () const { return m_encoding.full_nelts (); }
69
70 /* Return the number of input vectors being permuted. */
71 unsigned int ninputs () const { return m_ninputs; }
72
73 /* Return the number of elements in each input vector. */
74 poly_uint64 nelts_per_input () const { return m_nelts_per_input; }
75
76 /* Return the total number of input elements. */
77 poly_uint64 input_nelts () const { return m_ninputs * m_nelts_per_input; }
78
79 element_type clamp (element_type) const;
80 element_type operator[] (unsigned int i) const;
81 bool series_p (unsigned int, unsigned int, element_type, element_type) const;
82 bool all_in_range_p (element_type, element_type) const;
83 bool all_from_input_p (unsigned int) const;
84
85 private:
86 vec_perm_indices (const vec_perm_indices &);
87
88 vec_perm_builder m_encoding;
89 unsigned int m_ninputs;
90 poly_uint64 m_nelts_per_input;
91 };
92
93 bool tree_to_vec_perm_builder (vec_perm_builder *, tree);
94 tree vec_perm_indices_to_tree (tree, const vec_perm_indices &);
95 rtx vec_perm_indices_to_rtx (machine_mode, const vec_perm_indices &);
96
97 inline
98 vec_perm_indices::vec_perm_indices ()
99 : m_ninputs (0),
100 m_nelts_per_input (0)
101 {
102 }
103
104 /* Construct a permutation vector that selects between NINPUTS vector
105 inputs that have NELTS_PER_INPUT elements each. Take the elements of
106 the new vector from ELEMENTS, clamping each one to be in range. */
107
108 inline
109 vec_perm_indices::vec_perm_indices (const vec_perm_builder &elements,
110 unsigned int ninputs,
111 poly_uint64 nelts_per_input)
112 {
113 new_vector (elements, ninputs, nelts_per_input);
114 }
115
116 /* Return the canonical value for permutation vector element ELT,
117 taking into account the current number of input elements. */
118
119 inline vec_perm_indices::element_type
120 vec_perm_indices::clamp (element_type elt) const
121 {
122 element_type limit = input_nelts (), elem_within_input;
123 HOST_WIDE_INT input;
124 if (!can_div_trunc_p (elt, limit, &input, &elem_within_input))
125 return elt;
126
127 /* Treat negative elements as counting from the end. This only matters
128 if the vector size is not a power of 2. */
129 if (known_lt (elem_within_input, 0))
130 return elem_within_input + limit;
131
132 return elem_within_input;
133 }
134
135 /* Return the value of vector element I, which might or might not be
136 explicitly encoded. */
137
138 inline vec_perm_indices::element_type
139 vec_perm_indices::operator[] (unsigned int i) const
140 {
141 return clamp (m_encoding.elt (i));
142 }
143
144 /* Return true if the permutation vector only selects elements from
145 input I. */
146
147 inline bool
148 vec_perm_indices::all_from_input_p (unsigned int i) const
149 {
150 return all_in_range_p (i * m_nelts_per_input, m_nelts_per_input);
151 }
152
153 #endif