1 /* Function return value location for Linux/PPC64 ABI.
2 Copyright (C) 2005-2010, 2014 Red Hat, Inc.
3 This file is part of elfutils.
4
5 This file is free software; you can redistribute it and/or modify
6 it under the terms of either
7
8 * the GNU Lesser General Public License as published by the Free
9 Software Foundation; either version 3 of the License, or (at
10 your option) any later version
11
12 or
13
14 * the GNU General Public License as published by the Free
15 Software Foundation; either version 2 of the License, or (at
16 your option) any later version
17
18 or both in parallel, as here.
19
20 elfutils is distributed in the hope that it will be useful, but
21 WITHOUT ANY WARRANTY; without even the implied warranty of
22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 General Public License for more details.
24
25 You should have received copies of the GNU General Public License and
26 the GNU Lesser General Public License along with this program. If
27 not, see <http://www.gnu.org/licenses/>. */
28
29 #ifdef HAVE_CONFIG_H
30 # include <config.h>
31 #endif
32
33 #include <assert.h>
34 #include <dwarf.h>
35
36 #define BACKEND ppc64_
37 #include "libebl_CPU.h"
38
39
40 /* r3. */
41 static const Dwarf_Op loc_intreg[] =
42 {
43 { .atom = DW_OP_reg3 }
44 };
45 #define nloc_intreg 1
46
47 /* f1, or f1:f2, or f1:f4. */
48 static const Dwarf_Op loc_fpreg[] =
49 {
50 { .atom = DW_OP_regx, .number = 33 }, { .atom = DW_OP_piece, .number = 8 },
51 { .atom = DW_OP_regx, .number = 34 }, { .atom = DW_OP_piece, .number = 8 },
52 { .atom = DW_OP_regx, .number = 35 }, { .atom = DW_OP_piece, .number = 8 },
53 { .atom = DW_OP_regx, .number = 36 }, { .atom = DW_OP_piece, .number = 8 },
54 };
55 #define nloc_fpreg 1
56 #define nloc_fp2regs 4
57 #define nloc_fp4regs 8
58
59 /* vr2. */
60 static const Dwarf_Op loc_vmxreg[] =
61 {
62 { .atom = DW_OP_regx, .number = 1124 + 2 }
63 };
64 #define nloc_vmxreg 1
65
66 /* The return value is a structure and is actually stored in stack space
67 passed in a hidden argument by the caller. But, the compiler
68 helpfully returns the address of that space in r3. */
69 static const Dwarf_Op loc_aggregate[] =
70 {
71 { .atom = DW_OP_breg3, .number = 0 }
72 };
73 #define nloc_aggregate 1
74
75 int
ppc64_return_value_location(Dwarf_Die * functypedie,const Dwarf_Op ** locp)76 ppc64_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
77 {
78 /* Start with the function's type, and get the DW_AT_type attribute,
79 which is the type of the return value. */
80 Dwarf_Die die_mem, *typedie = &die_mem;
81 int tag = dwarf_peeled_die_type (functypedie, typedie);
82 if (tag <= 0)
83 return tag;
84
85 Dwarf_Word size;
86 switch (tag)
87 {
88 case -1:
89 return -1;
90
91 case DW_TAG_subrange_type:
92 if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
93 {
94 Dwarf_Attribute attr_mem, *attr;
95 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
96 typedie = dwarf_formref_die (attr, &die_mem);
97 tag = DWARF_TAG_OR_RETURN (typedie);
98 }
99 FALLTHROUGH;
100
101 case DW_TAG_base_type:
102 case DW_TAG_enumeration_type:
103 CASE_POINTER:
104 {
105 Dwarf_Attribute attr_mem;
106 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
107 &attr_mem), &size) != 0)
108 {
109 if (dwarf_is_pointer (tag))
110 size = 8;
111 else
112 return -1;
113 }
114 }
115
116 if (tag == DW_TAG_base_type)
117 {
118 Dwarf_Attribute attr_mem;
119 Dwarf_Word encoding;
120 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
121 &attr_mem),
122 &encoding) != 0)
123 return -1;
124
125 if (encoding == DW_ATE_float || encoding == DW_ATE_complex_float)
126 {
127 *locp = loc_fpreg;
128 if (size <= 8)
129 return nloc_fpreg;
130 if (size <= 16)
131 return nloc_fp2regs;
132 if (size <= 32)
133 return nloc_fp4regs;
134 }
135 }
136 if (size <= 8)
137 {
138 intreg:
139 *locp = loc_intreg;
140 return nloc_intreg;
141 }
142
143 FALLTHROUGH;
144 case DW_TAG_structure_type:
145 case DW_TAG_class_type:
146 case DW_TAG_union_type:
147 aggregate:
148 *locp = loc_aggregate;
149 return nloc_aggregate;
150
151 case DW_TAG_array_type:
152 {
153 Dwarf_Attribute attr_mem;
154 bool is_vector;
155 if (dwarf_formflag (dwarf_attr_integrate (typedie, DW_AT_GNU_vector,
156 &attr_mem), &is_vector) == 0
157 && is_vector)
158 {
159 *locp = loc_vmxreg;
160 return nloc_vmxreg;
161 }
162 }
163 FALLTHROUGH;
164
165 case DW_TAG_string_type:
166 if (dwarf_aggregate_size (typedie, &size) == 0 && size <= 8)
167 {
168 if (tag == DW_TAG_array_type)
169 {
170 /* Check if it's a character array. */
171 Dwarf_Attribute attr_mem, *attr;
172 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
173 typedie = dwarf_formref_die (attr, &die_mem);
174 tag = DWARF_TAG_OR_RETURN (typedie);
175 if (tag != DW_TAG_base_type)
176 goto aggregate;
177 if (dwarf_formudata (dwarf_attr_integrate (typedie,
178 DW_AT_byte_size,
179 &attr_mem),
180 &size) != 0)
181 return -1;
182 if (size != 1)
183 goto aggregate;
184 }
185 goto intreg;
186 }
187 goto aggregate;
188 }
189
190 /* XXX We don't have a good way to return specific errors from ebl calls.
191 This value means we do not understand the type, but it is well-formed
192 DWARF and might be valid. */
193 return -2;
194 }
195