1 /****************************************************************************
2 * *
3 * GNAT COMPILER COMPONENTS *
4 * *
5 * C U I N T P *
6 * *
7 * C Implementation File *
8 * *
9 * Copyright (C) 1992-2014, 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 "tree.h"
34
35 #include "ada.h"
36 #include "types.h"
37 #include "uintp.h"
38 #include "atree.h"
39 #include "elists.h"
40 #include "nlists.h"
41 #include "stringt.h"
42 #include "fe.h"
43 #include "ada-tree.h"
44 #include "gigi.h"
45
46 /* Universal integers are represented by the Uint type which is an index into
47 the Uints_Ptr table containing Uint_Entry values. A Uint_Entry contains an
48 index and length for getting the "digits" of the universal integer from the
49 Udigits_Ptr table.
50
51 For efficiency, this method is used only for integer values larger than the
52 constant Uint_Bias. If a Uint is less than this constant, then it contains
53 the integer value itself. The origin of the Uints_Ptr table is adjusted so
54 that a Uint value of Uint_Bias indexes the first element.
55
56 First define a utility function that operates like build_int_cst for
57 integral types and does a conversion to floating-point for real types. */
58
59 static tree
build_cst_from_int(tree type,HOST_WIDE_INT low)60 build_cst_from_int (tree type, HOST_WIDE_INT low)
61 {
62 if (SCALAR_FLOAT_TYPE_P (type))
63 return convert (type, build_int_cst (gnat_type_for_size (32, 0), low));
64 else
65 return build_int_cst_type (type, low);
66 }
67
68 /* Similar to UI_To_Int, but return a GCC INTEGER_CST or REAL_CST node,
69 depending on whether TYPE is an integral or real type. Overflow is tested
70 by the constant-folding used to build the node. TYPE is the GCC type of
71 the resulting node. */
72
73 tree
UI_To_gnu(Uint Input,tree type)74 UI_To_gnu (Uint Input, tree type)
75 {
76 tree gnu_ret;
77
78 /* We might have a TYPE with biased representation and be passed an
79 unbiased value that doesn't fit. We always use an unbiased type able
80 to hold any such possible value for intermediate computations, and
81 then rely on a conversion back to TYPE to perform the bias adjustment
82 when need be. */
83
84 int biased_type_p
85 = (TREE_CODE (type) == INTEGER_TYPE
86 && TYPE_BIASED_REPRESENTATION_P (type));
87
88 tree comp_type = biased_type_p ? get_base_type (type) : type;
89
90 if (Input <= Uint_Direct_Last)
91 gnu_ret = build_cst_from_int (comp_type, Input - Uint_Direct_Bias);
92 else
93 {
94 Int Idx = Uints_Ptr[Input].Loc;
95 Pos Length = Uints_Ptr[Input].Length;
96 Int First = Udigits_Ptr[Idx];
97 tree gnu_base;
98
99 gcc_assert (Length > 0);
100
101 /* The computations we perform below always require a type at least as
102 large as an integer not to overflow. FP types are always fine, but
103 INTEGER or ENUMERAL types we are handed may be too short. We use a
104 base integer type node for the computations in this case and will
105 convert the final result back to the incoming type later on. */
106 if (!SCALAR_FLOAT_TYPE_P (comp_type) && TYPE_PRECISION (comp_type) < 32)
107 comp_type = gnat_type_for_size (32, 0);
108
109 gnu_base = build_cst_from_int (comp_type, Base);
110
111 gnu_ret = build_cst_from_int (comp_type, First);
112 if (First < 0)
113 for (Idx++, Length--; Length; Idx++, Length--)
114 gnu_ret = fold_build2 (MINUS_EXPR, comp_type,
115 fold_build2 (MULT_EXPR, comp_type,
116 gnu_ret, gnu_base),
117 build_cst_from_int (comp_type,
118 Udigits_Ptr[Idx]));
119 else
120 for (Idx++, Length--; Length; Idx++, Length--)
121 gnu_ret = fold_build2 (PLUS_EXPR, comp_type,
122 fold_build2 (MULT_EXPR, comp_type,
123 gnu_ret, gnu_base),
124 build_cst_from_int (comp_type,
125 Udigits_Ptr[Idx]));
126 }
127
128 gnu_ret = convert (type, gnu_ret);
129
130 /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on GNU_RET. */
131 while ((TREE_CODE (gnu_ret) == NOP_EXPR
132 || TREE_CODE (gnu_ret) == NON_LVALUE_EXPR)
133 && TREE_TYPE (TREE_OPERAND (gnu_ret, 0)) == TREE_TYPE (gnu_ret))
134 gnu_ret = TREE_OPERAND (gnu_ret, 0);
135
136 return gnu_ret;
137 }
138
139 /* Similar to UI_From_Int, but take a GCC INTEGER_CST. We use UI_From_Int
140 when possible, i.e. for a 32-bit signed value, to take advantage of its
141 built-in caching mechanism. For values of larger magnitude, we compute
142 digits into a vector and call Vector_To_Uint. */
143
144 Uint
UI_From_gnu(tree Input)145 UI_From_gnu (tree Input)
146 {
147 tree gnu_type = TREE_TYPE (Input), gnu_base, gnu_temp;
148 /* UI_Base is defined so that 5 Uint digits is sufficient to hold the
149 largest possible signed 64-bit value. */
150 const int Max_For_Dint = 5;
151 int v[Max_For_Dint], i;
152 Vector_Template temp;
153 Int_Vector vec;
154
155 #if HOST_BITS_PER_WIDE_INT == 64
156 /* On 64-bit hosts, host_integerp tells whether the input fits in a
157 signed 64-bit integer. Then a truncation tells whether it fits
158 in a signed 32-bit integer. */
159 if (host_integerp (Input, 0))
160 {
161 HOST_WIDE_INT hw_input = TREE_INT_CST_LOW (Input);
162 if (hw_input == (int) hw_input)
163 return UI_From_Int (hw_input);
164 }
165 else
166 return No_Uint;
167 #else
168 /* On 32-bit hosts, host_integerp tells whether the input fits in a
169 signed 32-bit integer. Then a sign test tells whether it fits
170 in a signed 64-bit integer. */
171 if (host_integerp (Input, 0))
172 return UI_From_Int (TREE_INT_CST_LOW (Input));
173 else if (TREE_INT_CST_HIGH (Input) < 0 && TYPE_UNSIGNED (gnu_type))
174 return No_Uint;
175 #endif
176
177 gnu_base = build_int_cst (gnu_type, UI_Base);
178 gnu_temp = Input;
179
180 for (i = Max_For_Dint - 1; i >= 0; i--)
181 {
182 v[i] = tree_low_cst (fold_build1 (ABS_EXPR, gnu_type,
183 fold_build2 (TRUNC_MOD_EXPR, gnu_type,
184 gnu_temp, gnu_base)),
185 0);
186 gnu_temp = fold_build2 (TRUNC_DIV_EXPR, gnu_type, gnu_temp, gnu_base);
187 }
188
189 temp.Low_Bound = 1, temp.High_Bound = Max_For_Dint;
190 vec.Array = v, vec.Bounds = &temp;
191 return Vector_To_Uint (vec, tree_int_cst_sgn (Input) < 0);
192 }
193