1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * C U I N T P *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2020, Free Software Foundation, Inc. *
10 * *
11 * GNAT is free software; you can redistribute it and/or modify it under *
12 * terms of the GNU General Public License as published by the Free Soft- *
13 * ware Foundation; either version 3, or (at your option) any later ver- *
14 * sion. GNAT is distributed in the hope that it will be useful, but WITH- *
15 * OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY *
16 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License *
17 * for more details. You should have received a copy of the GNU General *
18 * Public License along with GCC; see the file COPYING3. If not see *
19 * <http://www.gnu.org/licenses/>. *
20 * *
21 * GNAT was originally developed by the GNAT team at New York University. *
22 * Extensive contributions were provided by Ada Core Technologies Inc. *
23 * *
24 ****************************************************************************/
25
26 /* This file corresponds to the Ada package body Uintp. It was created
27 manually from the files uintp.ads and uintp.adb. */
28
29 #include "config.h"
30 #include "system.h"
31 #include "coretypes.h"
32 #include "tm.h"
33 #include "vec.h"
34 #include "alias.h"
35 #include "tree.h"
36 #include "inchash.h"
37 #include "fold-const.h"
38
39 #include "ada.h"
40 #include "types.h"
41 #include "uintp.h"
42 #include "ada-tree.h"
43 #include "gigi.h"
44
45 /* Universal integers are represented by the Uint type which is an index into
46 the Uints_Ptr table containing Uint_Entry values. A Uint_Entry contains an
47 index and length for getting the "digits" of the universal integer from the
48 Udigits_Ptr table.
49
50 For efficiency, this method is used only for integer values larger than the
51 constant Uint_Bias. If a Uint is less than this constant, then it contains
52 the integer value itself. The origin of the Uints_Ptr table is adjusted so
53 that a Uint value of Uint_Bias indexes the first element.
54
55 First define a utility function that is build_int_cst for integral types and
56 does a conversion for floating-point types. */
57
58 static tree
build_cst_from_int(tree type,HOST_WIDE_INT low)59 build_cst_from_int (tree type, HOST_WIDE_INT low)
60 {
61 if (SCALAR_FLOAT_TYPE_P (type))
62 return convert (type, build_int_cst (gnat_type_for_size (32, 0), low));
63 else
64 return build_int_cst (type, low);
65 }
66
67 /* Similar to UI_To_Int, but return a GCC INTEGER_CST or REAL_CST node,
68 depending on whether TYPE is an integral or real type. Overflow is tested
69 by the constant-folding used to build the node. TYPE is the GCC type of
70 the resulting node. */
71
72 tree
UI_To_gnu(Uint Input,tree type)73 UI_To_gnu (Uint Input, tree type)
74 {
75 /* We might have a TYPE with biased representation and be passed an unbiased
76 value that doesn't fit. We always use an unbiased type to be able to hold
77 any such possible value for intermediate computations and then rely on a
78 conversion back to TYPE to perform the bias adjustment when need be. */
79 tree comp_type
80 = TREE_CODE (type) == INTEGER_TYPE && TYPE_BIASED_REPRESENTATION_P (type)
81 ? get_base_type (type) : type;
82 tree gnu_ret;
83
84 if (Input <= Uint_Direct_Last)
85 gnu_ret = build_cst_from_int (comp_type, Input - Uint_Direct_Bias);
86 else
87 {
88 Int Idx = Uints_Ptr[Input].Loc;
89 Pos Length = Uints_Ptr[Input].Length;
90 Int First = Udigits_Ptr[Idx];
91 tree gnu_base;
92
93 gcc_assert (Length > 0);
94
95 /* The computations we perform below always require a type at least as
96 large as an integer not to overflow. FP types are always fine, but
97 INTEGER or ENUMERAL types we are handed may be too short. We use a
98 base integer type node for the computations in this case and will
99 convert the final result back to the incoming type later on. */
100 if (!SCALAR_FLOAT_TYPE_P (comp_type) && TYPE_PRECISION (comp_type) < 32)
101 comp_type = gnat_type_for_size (32, 0);
102
103 gnu_base = build_cst_from_int (comp_type, Base);
104
105 gnu_ret = build_cst_from_int (comp_type, First);
106 if (First < 0)
107 for (Idx++, Length--; Length; Idx++, Length--)
108 gnu_ret = fold_build2 (MINUS_EXPR, comp_type,
109 fold_build2 (MULT_EXPR, comp_type,
110 gnu_ret, gnu_base),
111 build_cst_from_int (comp_type,
112 Udigits_Ptr[Idx]));
113 else
114 for (Idx++, Length--; Length; Idx++, Length--)
115 gnu_ret = fold_build2 (PLUS_EXPR, comp_type,
116 fold_build2 (MULT_EXPR, comp_type,
117 gnu_ret, gnu_base),
118 build_cst_from_int (comp_type,
119 Udigits_Ptr[Idx]));
120 }
121
122 gnu_ret = convert (type, gnu_ret);
123
124 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on GNU_RET. */
125 while ((TREE_CODE (gnu_ret) == NOP_EXPR
126 || TREE_CODE (gnu_ret) == NON_LVALUE_EXPR)
127 && TREE_TYPE (TREE_OPERAND (gnu_ret, 0)) == TREE_TYPE (gnu_ret))
128 gnu_ret = TREE_OPERAND (gnu_ret, 0);
129
130 return gnu_ret;
131 }
132
133 /* Similar to UI_From_Int, but take a GCC INTEGER_CST. We use UI_From_Int
134 when possible, i.e. for a 32-bit signed value, to take advantage of its
135 built-in caching mechanism. For values of larger magnitude, we compute
136 digits into a vector and call Vector_To_Uint. */
137
138 Uint
UI_From_gnu(tree Input)139 UI_From_gnu (tree Input)
140 {
141 tree gnu_type = TREE_TYPE (Input), gnu_base, gnu_temp;
142 /* UI_Base is defined so that 5 Uint digits is sufficient to hold the
143 largest possible signed 64-bit value. */
144 const int Max_For_Dint = 5;
145 int v[Max_For_Dint];
146 Vector_Template temp;
147 Int_Vector vec;
148
149 #if HOST_BITS_PER_WIDE_INT < 64
150 #error unsupported HOST_BITS_PER_WIDE_INT setting
151 #endif
152
153 /* On 64-bit hosts, tree_fits_shwi_p tells whether the input fits in
154 a signed 64-bit integer. Then a truncation tells whether it fits
155 in a signed 32-bit integer. */
156 if (tree_fits_shwi_p (Input))
157 {
158 HOST_WIDE_INT hw_input = tree_to_shwi (Input);
159 if (hw_input == (int) hw_input)
160 return UI_From_Int (hw_input);
161 }
162 else
163 return No_Uint;
164
165 gnu_base = build_int_cst (gnu_type, UI_Base);
166 gnu_temp = Input;
167
168 for (int i = Max_For_Dint - 1; i >= 0; i--)
169 {
170 v[i] = tree_to_shwi (fold_build1 (ABS_EXPR, gnu_type,
171 fold_build2 (TRUNC_MOD_EXPR, gnu_type,
172 gnu_temp, gnu_base)));
173 gnu_temp = fold_build2 (TRUNC_DIV_EXPR, gnu_type, gnu_temp, gnu_base);
174 }
175
176 temp.Low_Bound = 1;
177 temp.High_Bound = Max_For_Dint;
178 vec.Bounds = &temp;
179 vec.Array = v;
180 return Vector_To_Uint (vec, tree_int_cst_sgn (Input) < 0);
181 }
182