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 /* Fall through. */
100
101 case DW_TAG_base_type:
102 case DW_TAG_enumeration_type:
103 case DW_TAG_pointer_type:
104 case DW_TAG_ptr_to_member_type:
105 {
106 Dwarf_Attribute attr_mem;
107 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
108 &attr_mem), &size) != 0)
109 {
110 if (tag == DW_TAG_pointer_type || tag == DW_TAG_ptr_to_member_type)
111 size = 8;
112 else
113 return -1;
114 }
115 }
116
117 if (tag == DW_TAG_base_type)
118 {
119 Dwarf_Attribute attr_mem;
120 Dwarf_Word encoding;
121 if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
122 &attr_mem),
123 &encoding) != 0)
124 return -1;
125
126 if (encoding == DW_ATE_float || encoding == DW_ATE_complex_float)
127 {
128 *locp = loc_fpreg;
129 if (size <= 8)
130 return nloc_fpreg;
131 if (size <= 16)
132 return nloc_fp2regs;
133 if (size <= 32)
134 return nloc_fp4regs;
135 }
136 }
137 if (size <= 8)
138 {
139 intreg:
140 *locp = loc_intreg;
141 return nloc_intreg;
142 }
143
144 /* Else fall through. */
145 case DW_TAG_structure_type:
146 case DW_TAG_class_type:
147 case DW_TAG_union_type:
148 aggregate:
149 *locp = loc_aggregate;
150 return nloc_aggregate;
151
152 case DW_TAG_array_type:
153 {
154 Dwarf_Attribute attr_mem;
155 bool is_vector;
156 if (dwarf_formflag (dwarf_attr_integrate (typedie, DW_AT_GNU_vector,
157 &attr_mem), &is_vector) == 0
158 && is_vector)
159 {
160 *locp = loc_vmxreg;
161 return nloc_vmxreg;
162 }
163 }
164 /* Fall through. */
165
166 case DW_TAG_string_type:
167 if (dwarf_aggregate_size (typedie, &size) == 0 && size <= 8)
168 {
169 if (tag == DW_TAG_array_type)
170 {
171 /* Check if it's a character array. */
172 Dwarf_Attribute attr_mem, *attr;
173 attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
174 typedie = dwarf_formref_die (attr, &die_mem);
175 tag = DWARF_TAG_OR_RETURN (typedie);
176 if (tag != DW_TAG_base_type)
177 goto aggregate;
178 if (dwarf_formudata (dwarf_attr_integrate (typedie,
179 DW_AT_byte_size,
180 &attr_mem),
181 &size) != 0)
182 return -1;
183 if (size != 1)
184 goto aggregate;
185 }
186 goto intreg;
187 }
188 goto aggregate;
189 }
190
191 /* XXX We don't have a good way to return specific errors from ebl calls.
192 This value means we do not understand the type, but it is well-formed
193 DWARF and might be valid. */
194 return -2;
195 }
196